WorldWideScience

Sample records for unit blade section

  1. New morphing blade section designs and structural solutions for smart blades

    DEFF Research Database (Denmark)

    Karakalas, Anargyros A.; Machairas, Theodore; Solomou, Alexandros

    2015-01-01

    and manufacturing processes constraints. Down selection of design based on results of analysis (for input to Task 2.3) was also performed. Following solutions were investigated:  Morphing blade sections with Shape Memory Alloys (SMA) by University of Patras  Morphing blade sections using an elastomer of zero...... Poisson ratio by University of Bristol  Morphing blade sections involving an innovative mechanism by Denmarks University of Technology The work performed on these three concepts is described in individual chapters of the present report. Section 2 discusses the concept using shape memory alloys, section 3...... of the present report. The solutions using Shape Memory Alloys, as well as an elastomer of zero Poisson ratio have a quite low technological readiness level (TRL). Both are inspired through the aeronautics sector, yet there are different challenges to address when designing for wind turbine blades. The size...

  2. An evaluation of wind turbine blade cross section analysis techniques.

    Energy Technology Data Exchange (ETDEWEB)

    Paquette, Joshua A.; Griffith, Daniel Todd; Laird, Daniel L.; Resor, Brian Ray

    2010-03-01

    The blades of a modern wind turbine are critical components central to capturing and transmitting most of the load experienced by the system. They are complex structural items composed of many layers of fiber and resin composite material and typically, one or more shear webs. Large turbine blades being developed today are beyond the point of effective trial-and-error design of the past and design for reliability is always extremely important. Section analysis tools are used to reduce the three-dimensional continuum blade structure to a simpler beam representation for use in system response calculations to support full system design and certification. One model simplification approach is to analyze the two-dimensional blade cross sections to determine the properties for the beam. Another technique is to determine beam properties using static deflections of a full three-dimensional finite element model of a blade. This paper provides insight into discrepancies observed in outputs from each approach. Simple two-dimensional geometries and three-dimensional blade models are analyzed in this investigation. Finally, a subset of computational and experimental section properties for a full turbine blade are compared.

  3. Numerical study of Wavy Blade Section for Wind Turbines

    Science.gov (United States)

    Kobæk, C. M.; Hansen, M. O. L.

    2016-09-01

    The Wavy Blade concept is inspired by the unique flipper of a humpback whale, characterized by the tubercles located at the leading edge. It has been suggested that this shape may have been a result of a natural selection process, since this flipper under some circumstances can produce higher lift than a flipper having a smooth trailing edge and thus could be potentially beneficial when catching food. A thorough literature study of the Wavy Blade concept is made and followed by CFD computations of two wavy blade geometries and a comparison with their baseline S809 airfoil at conditions more relevant for modern wind turbines. The findings in the literature from geometries similar to the hump back whale flipper indicate that the aerodynamic performance can be improved at high angles of attack, but sometimes at the expense of a lower lift slope and increased drag before stall. The numerical results for a blade section based on the S809 airfoil are, however, not as promising as some of the findings reported in the literature for the whale flipper at high angles of attack. These first CFD computations using a thicker airfoil and a higher Reynolds number than the whale flipper indicate that the results may very well depend on the actual airfoil geometry and perhaps also the Reynolds number, and future studies are necessary in order to illuminate this further.

  4. Unsustainable Wind Turbine Blade Disposal Practices in the United States.

    Science.gov (United States)

    Ramirez-Tejeda, Katerin; Turcotte, David A; Pike, Sarah

    2017-02-01

    Finding ways to manage the waste from the expected high number of wind turbine blades in need of disposal is crucial to harvest wind energy in a truly sustainable manner. Landfilling is the most cost-effective disposal method in the United States, but it imposes significant environmental impacts. Thermal, mechanical, and chemical processes allow for some energy and/or material recovery, but they also carry potential negative externalities. This article explores the main economic and environmental issues with various wind turbine blade disposal methods. We argue for the necessity of policy intervention that encourages industry to develop better technologies to make wind turbine blade disposal sustainable, both environmentally and economically. We present some of the technological initiatives being researched, such as the use of bio-derived resins and thermoplastic composites in the manufacturing process of the blades.

  5. Numerical study of Wavy Blade Section for Wind Turbines

    DEFF Research Database (Denmark)

    Kobæk, C. M.; Hansen, Martin Otto Laver

    2016-01-01

    relevant for modern wind turbines. The findings in the literature from geometries similar to the hump back whale flipper indicate that the aerodynamic performance can be improved at high angles of attack, but sometimes at the expense of a lower lift slope and increased drag before stall. The numerical...... results for a blade section based on the S809 airfoil are, however, not as promising as some of the findings reported in the literature for the whale flipper at high angles of attack. These first CFD computations using a thicker airfoil and a higher Reynolds number than the whale flipper indicate...

  6. blades

    Directory of Open Access Journals (Sweden)

    Shashishekara S. Talya

    1999-01-01

    Full Text Available Design optimization of a gas turbine blade geometry for effective film cooling toreduce the blade temperature has been done using a multiobjective optimization formulation. Three optimization formulations have been used. In the first, the average blade temperature is chosen as the objective function to be minimized. An upper bound constraint has been imposed on the maximum blade temperature. In the second, the maximum blade temperature is chosen as the objective function to be minimized with an upper bound constraint on the average blade temperature. In the third formulation, the blade average and maximum temperatures are chosen as objective functions. Shape optimization is performed using geometric parameters associated with film cooling and blade external shape. A quasi-three-dimensional Navier–Stokes solver for turbomachinery flows is used to solve for the flow field external to the blade with appropriate modifications to incorporate the effect of film cooling. The heat transfer analysis for temperature distribution within the blade is performed by solving the heat diffusion equation using the finite element method. The multiobjective Kreisselmeier–Steinhauser function approach has been used in conjunction with an approximate analysis technique for optimization. The results obtained using both formulations are compared with reference geometry. All three formulations yield significant reductions in blade temperature with the multiobjective formulation yielding largest reduction in blade temperature.

  7. BLADE SECTION DESIGN OF MARINE PROPELLERS WITH MAXIMUM CAVITATION INCEPTION SPEED

    Institute of Scientific and Technical Information of China (English)

    ZENG Zhi-bo; KUIPER Gert

    2012-01-01

    Kuiper and Jessup (1993) developed a design method for propellers in a wake based on the Eppler foil design method.The optimized section is transformed into the three-dimensional propeller flow using the approach of the effective blade sections.Effective blade sections are two-dimensional sections in two-dimensional flow which have the same chordwise loading distribution as the three-dimensional blade sections of a propeller.However,the design procedure is laborious in two aspects:finding an optimum blade section using the Eppler program requires much skill of the designer,and transforming the two-dimensional blade section into a propeller blade section in three-dimensional flow is complex.In this work,these two problems were coped with.A blade section design procedure was presented using an optimization technique and an alternative procedure for the effective blade section is developed using a lifting surface design method.To validate the method a benchmark model of a naval ship was used.This benchmark model was extended by new appendices and a reference propeller,and designed using conventional design methods.This reference propeller was optimized using the new design procedure and model tests were carried out.Special attention was given to the data of the model and the reference propeller,to make the configuration suitable for the Reynolds-Averaged Navier-Stokes (RANS) calculations.

  8. Wind turbine blade, has internal reinforcing floor connected inside shell, where floor has cross section transversely to longitudinal extension of blade that extends in direction from trailing edge to leading edge of blade

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a reinforced blade for a wind turbine, and in particular to a wind turbine blade comprising a shell having a section with an aerodynamic profile, and at least one internal reinforcing floor connected inside the shell and extending substantially along the profile...... chord in order to increase the strength of the blade and to prevent or reduce deformations of the surface of the blade caused by edgewise and flapwise loading of the blade structure....

  9. Blade Sections in Streamwise Oscillations into Reverse Flow

    Science.gov (United States)

    2015-05-07

    blade surges into the freestream and dropping to near zero as the blade retreats. At this high angle of attack, however, maxi - mum lift no longer lags...progresses, stronger viscous effects might cause precipitation of deep stall, a weak - ening of bound circulation, and a drop in lift ahead of the drop

  10. Stall Flutter Control of a Smart Blade Section Undergoing Asymmetric Limit Oscillations

    Directory of Open Access Journals (Sweden)

    Nailu Li

    2016-01-01

    Full Text Available Stall flutter is an aeroelastic phenomenon resulting in unwanted oscillatory loads on the blade, such as wind turbine blade, helicopter rotor blade, and other flexible wing blades. Although the stall flutter and related aeroelastic control have been studied theoretically and experimentally, microtab control of asymmetric limit cycle oscillations (LCOs in stall flutter cases has not been generally investigated. This paper presents an aeroservoelastic model to study the microtab control of the blade section undergoing moderate stall flutter and deep stall flutter separately. The effects of different dynamic stall conditions and the consequent asymmetric LCOs for both stall cases are simulated and analyzed. Then, for the design of the stall flutter controller, the potential sensor signal for the stall flutter, the microtab control capability of the stall flutter, and the control algorithm for the stall flutter are studied. The improvement and the superiority of the proposed adaptive stall flutter controller are shown by comparison with a simple stall flutter controller.

  11. New Design of Blade Untwisting Device of Cyclone Unit

    Directory of Open Access Journals (Sweden)

    D. I. Misiulia

    2010-01-01

    Full Text Available The paper presents a new design of a blade untwisting device where blades are considered as a main element of the device. A profile of the blades corresponds to a circular arch. An inlet angle of  the blades is determined by stream aerodynamics in an exhaust pipe, and an exit angle is determined by rectilinear gas motion. Optimum geometrical parameters of the untwisting device have been determined and its application allows to reduce a pressure drop in the ЦН-15 cyclones by 28–30 % while screw-blade untwisting device recovers only 19–20 % of energy.

  12. Using a shock control bump to improve the performance of an axial compressor blade section

    Science.gov (United States)

    Mazaheri, K.; Khatibirad, S.

    2017-03-01

    Here, we use numerical analysis to study the effects of a shock control bump (SCB) on the performance of a transonic axial compressor blade section and to optimize its shape and location to improve the compressor performance. A section of the NASA rotor 67 blade is used for this study. Two Bézier curves, each consisting of seven control points, are used to model the suction and pressure surfaces of the blade section. The SCB is modeled with the Hicks-Henne function and, using five design parameters, is added to the suction side. The total pressure loss through a cascade of blade sections is selected as the cost function. A continuous adjoint optimization method is used along with a RANS solver to find a new blade section shape. A grid independence study is performed, and all optimization and flow solver algorithms are validated. Two single-point optimizations are performed in the design condition and in an off-design condition. It is shown that both optimized shapes have overall better performance for both on-design and off-design conditions. An analysis is given regarding how the SCB has changed the wave structure between blade sections resulting in a more favorable flow pattern.

  13. Section curve reconstruction and mean-camber curve extraction of a point-sampled blade surface.

    Directory of Open Access Journals (Sweden)

    Wen-long Li

    Full Text Available The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization.

  14. An experimental investigation into cavitation behaviour and pressure characteristics of alternative blade sections for propellers

    Science.gov (United States)

    Korkut, Emin; Atlar, Mehmet; Wang, Dazheng

    2013-03-01

    During the final quarter of the last century considerable efforts have been spent to reduce the hull pressure fluctuations caused by unsteady propeller cavitation. This has resulted in further changes in propeller design characteristics including increased skew, tip unloading and introduction of "New Blade Sections" (NBS) designed on the basis of the so-called Eppler code. An experimental study was carried out to investigate flow characteristics of alternative two-dimensional (2-D) blade sections of rectangular planform, one of which was the New Blade Section (NBS) developed in Newcastle University and other was based on the well-known National Advisory Committee for Aeronautics (NACA) section. The experiments comprised the cavitation observations and the measurements of the local velocity distribution around the blade sections by using a 2-D Laser Doppler Anemometry (LDA) system. Analysis of the cavitation tests demonstrated that the two blade sections presented very similar bucket shapes with virtually no width at the bottom but relatively favourable buckets arms at the suction and pressure sides for the NACA section. Similarly, pressure analysis of the sections displayed a slightly larger value for the NBS pressure peak. The comparative overall pressure distributions around the sections suggested that the NBS might be more susceptible to cavitation than the NACA section. This can be closely related to the fundamental shape of the NBS with very fine leading edge. Therefore a further investigation into the modification of the leading edge should be considered to improve the cavitation behaviour of the NBS.

  15. Fundamental aeroelastic properties of a bend–twist coupled blade section

    DEFF Research Database (Denmark)

    Stäblein, Alexander R.; Hansen, Morten Hartvig; Pirrung, Georg

    2017-01-01

    The effects of bend–twist coupling on the aeroelastic modal properties and stability limits of a two-dimensional blade section in attached flow are investigated. Bend–twist coupling is introduced in the stiffness matrix of the structural blade section model. The structural model is coupled...... with an unsteady aerodynamic model in a linearised state–space formulation. A numerical study is performed using structural and aerodynamic parameters representative for wind turbine blades. It is shown that damping of the edgewise mode is primarily influenced by the work of the lift which is close to antiphase...... to an edgetwist flutter instability at much lower inflow speeds than the uncoupled blade section. Flap–twist coupling results in a moderate reduction of the flutter speed for twist to feather and divergence for twist to stall....

  16. A qualitative analytical investigation of geometrically nonlinear effects in wind turbine blade cross sections

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Bitsche, Robert

    2015-01-01

    section, that was inspired by a wind turbine blade, it is demonstrated that geometric nonlinear effects can induce an in-plane opening deformation in re-entrant corners that may decrease the fatigue life. The opening effect induces Mode-I stress intensity factors which exceed the threshold for fatigue...... for computationally efficient numerical analysis approaches of structures that comprise complex geometry and anisotropic material behaviour – such as wind turbine rotor blades....

  17. Flow Integrating Section for a Gas Turbine Engine in Which Turbine Blades are Cooled by Full Compressor Flow

    Energy Technology Data Exchange (ETDEWEB)

    Steward, W. Gene

    1999-11-14

    Routing of full compressor flow through hollow turbine blades achieves unusually effective blade cooling and allows a significant increase in turbine inlet gas temperature and, hence, engine efficiency. The invention, ''flow integrating section'' alleviates the turbine dissipation of kinetic energy of air jets leaving the hollow blades as they enter the compressor diffuser.

  18. Cooling of Gas Turbines. 6; Computed Temperature Distribution Through Cross Section of Water-Cooled Turbine Blade

    Science.gov (United States)

    Livingood, John N. B.; Sams, Eldon W.

    1947-01-01

    A theoretical analysis of the cross-sectional temperature distribution of a water-cooled turbine blade was made using the relaxation method to solve the differential equation derived from the analysis. The analysis was applied to specific turbine blade and the studies icluded investigations of the accuracy of simple methods to determine the temperature distribution along the mean line of the rear part of the blade, of the possible effect of varying the perimetric distribution of the hot gas-to -metal heat transfer coefficient, and of the effect of changing the thermal conductivity of the blade metal for a constant cross sectional area blade with two quarter inch diameter coolant passages.

  19. Wind tunnel testing of a full scale helicopter blade section with an upstream active Gurney flap

    NARCIS (Netherlands)

    Loendersloot, R.; Freire Gomez, J.; Booker, J.D.

    2014-01-01

    Wind tunnel tests were performed on an aerofoil section comparable to that of a full scale helicopter blade section with an upstream active Gurney flap in the framework of the European project CleanSky ITD Green RotorCraft. A modified NACA0012 profile was used, with 23 Kulite pressure transducers em

  20. Effect of Elevated Free Stream Turbulence on the Hydrodynamic Performance of a Tidal Turbine Blade Section

    Science.gov (United States)

    Vinod, Ashwin; Lawrence, Angela; Banerjee, Arindam

    2016-11-01

    The effects of elevated freestream turbulence (FST) on the performance of a tidal turbine blade is studied using laboratory experiments. Of interest for the current investigation is elevated levels of FST in the range of 6-24% that is prevalent in deployment sites of tidal turbines. A constant chord, no twist blade section (SG6043) is tested at an operating Reynolds number of 1.5x105 and at angles of attack ranging from -90o to +90o. The parameter space encompasses the entire operational range of a tidal turbine that includes flow reversal. Multiple levels of controlled FST are achieved using an active grid type turbulence generator placed at the entrance to the water tunnel test section. The hydrodynamic loads experienced by the blade section are measured using a 3-axis load cell; a Stereo-PIV technique is used to analyze the flow field around the blade. The results indicate that elevated levels of FST cause a delay in flow separation when compared to the case of a laminar freestream. Furthermore, the lift to drag ratio of the blade is considerably altered depending on the level of FST and angle of attack tested.

  1. Updating Finite Element Model of a Wind Turbine Blade Section Using Experimental Modal Analysis Results

    DEFF Research Database (Denmark)

    Luczak, Marcin; Manzato, Simone; Peeters, Bart;

    2014-01-01

    of model parameters was selected for the model updating process. Design of experiment and response surface method was implemented to find values of model parameters yielding results closest to the experimental. The updated finite element model is producing results more consistent with the measurement...... is to validate finite element model of the modified wind turbine blade section mounted in the flexible support structure accordingly to the experimental results. Bend-twist coupling was implemented by adding angled unidirectional layers on the suction and pressure side of the blade. Dynamic test and simulations...... were performed on a section of a full scale wind turbine blade provided by Vestas Wind Systems A/S. The numerical results are compared to the experimental measurements and the discrepancies are assessed by natural frequency difference and modal assurance criterion. Based on sensitivity analysis, set...

  2. Reflection plane tests of a wind turbine blade tip section with ailerons

    Science.gov (United States)

    Savino, J. M.; Nyland, T. W.; Birchenough, A. G.; Jordan, F. L.; Campbell, N. K.

    1985-01-01

    Tests were conducted in the NASA Langley 30 by 60 foot Wind Tunnel on a full scale 7.31 m (24 ft) long tip section of a wind turbine rotor blade. The blade tip section was built with ailerons on the trailing edge. The ailerons, which spanned a length of 6.1 m (20 ft), were designed so that two types could be evaluated: the plain and the balanced. The ailerons were hinged on the suction surface at the 0.62 X chord station behind the leading edge. The purpose of the tests was to measure the aerodynamic characteristics of the blade section for: an angle of attack range from 0 deg to 90 deg aileron deflections from 0 deg to -90 deg, and Reynolds numbers of 0.79 and 1.5 x 10 to the 6th power. These data were then used to determine which aileron configuration had the most desirable rotor control and aerodynamic braking characteristics. Tests were also run to determine the effects of vortex generators, leading edge roughness, and the gaps between the aileron sections on the lift, drag, and chordwise force coefficients of the blade tip section.

  3. Updating Finite Element Model of a Wind Turbine Blade Section Using Experimental Modal Analysis Results

    Directory of Open Access Journals (Sweden)

    Marcin Luczak

    2014-01-01

    Full Text Available This paper presents selected results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study of the structural dynamics of a bend-twist coupled full scale section of a wind turbine blade structure. The main goal of the conducted research is to validate finite element model of the modified wind turbine blade section mounted in the flexible support structure accordingly to the experimental results. Bend-twist coupling was implemented by adding angled unidirectional layers on the suction and pressure side of the blade. Dynamic test and simulations were performed on a section of a full scale wind turbine blade provided by Vestas Wind Systems A/S. The numerical results are compared to the experimental measurements and the discrepancies are assessed by natural frequency difference and modal assurance criterion. Based on sensitivity analysis, set of model parameters was selected for the model updating process. Design of experiment and response surface method was implemented to find values of model parameters yielding results closest to the experimental. The updated finite element model is producing results more consistent with the measurement outcomes.

  4. Investigation of the compressible flow through the tip-section turbine blade cascade with supersonic inlet

    Science.gov (United States)

    Luxa, Martin; Příhoda, Jaromír; Šimurda, David; Straka, Petr; Synáč, Jaroslav

    2016-04-01

    The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical (interferometry and schlieren method) and pneumatic measurements provide more information about the behaviour and nature of basic phenomena occurring in the profile cascade flow field. The numerical simulation was carried out by means of the EARSM turbulence model according to Hellsten [5] completed by the bypass transition model with the algebraic equation for the intermittency coefficient proposed by Straka and Příhoda [6] and implemented into the in-house numerical code. The investigation was focused particularly on the effect of shock waves on the shear layer development including the laminar/turbulent transition. Interactions of shock waves with shear layers on both sides of the blade result usually in the transition in attached and/ or separated flow and so to the considerable impact to the flow structure and energy losses in the blade cascade.

  5. Numerical Investigation of Flapwise-Torsional Vibration Model of a Smart Section Blade with Microtab

    Directory of Open Access Journals (Sweden)

    Nailu Li

    2015-01-01

    Full Text Available This study presents a method to develop an aeroelastic model of a smart section blade equipped with microtab. The model is suitable for potential passive vibration control study of the blade section in classic flutter. Equations of the model are described by the nondimensional flapwise and torsional vibration modes coupled with the aerodynamic model based on the Theodorsen theory and aerodynamic effects of the microtab based on the wind tunnel experimental data. The aeroelastic model is validated using numerical data available in the literature and then utilized to analyze the microtab control capability on flutter instability case and divergence instability case. The effectiveness of the microtab is investigated with the scenarios of different output controllers and actuation deployments for both instability cases. The numerical results show that the microtab can effectively suppress both vibration modes with the appropriate choice of the output feedback controller.

  6. Aeroservoelastic Pitch Control of Stall-Induced Flap/Lag Flutter of Wind Turbine Blade Section

    Directory of Open Access Journals (Sweden)

    Tingrui Liu

    2015-01-01

    Full Text Available The aim of this paper is to analyze aeroelastic stability, especially flutter suppression for aeroelastic instability. Effects of aeroservoelastic pitch control for flutter suppression on wind turbine blade section subjected to combined flap and lag motions are rarely studied. The work is dedicated to solving destructive flapwise and edgewise instability of stall-induced flutter of wind turbine blade by aeroservoelastic pitch control. The aeroelastic governing equations combine a flap/lag structural model and an unsteady nonlinear aerodynamic model. The nonlinear resulting equations are linearized by small perturbation about the equilibrium point. The instability characteristics of stall-induced flap/lag flutter are investigated. Pitch actuator is described by a second-order model. The aeroservoelastic control is analyzed by three types of optimal PID controllers, two types of fuzzy PID controllers, and neural network PID controllers. The fuzzy controllers are developed based on Sugeno model and intuition method with good results achieved. A single neuron PID control strategy with improved Hebb learning algorithm and a radial basic function neural network PID algorithm are applied and performed well in the range of extreme wind speeds.

  7. Influences of attack angle and mach number on aerodynamic characters of typical sections of extra-long blade in a steam turbine

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On super-sonic or trans-sonic planar cascade wind tunnel of free jet intermittent type, wind blowing experiments were performed on the typical sections of stator and rotor blades in the last stage of ultra-ultra-critical steam turbine with extra-long blade of 1200mm. The influences of attack angle and Mach number on the aerodynamic performances of these sections of the blade profiles were verified, and their operating ranges were also specified.

  8. The Effect of Blade-Section Thickness Ratio on the Aerodynamic Characteristics of Related Full-Scale Propellers at Mach Numbers up to 0.65

    Science.gov (United States)

    Maynard, Julian D; Steinberg, Seymour

    1953-01-01

    The results of an investigation of two 10-foot-diameter, two-blade NACA propellers are presented for a range of blade angles from 20 degrees to 55 degrees at airspeeds up to 500 miles per hour. These results are compared with those from previous investigations of five related NACA propellers in order to evaluate the effects of blade-section thickness ratios on propeller aerodynamic characteristics.

  9. Unsteady aerodynamics of reverse flow dynamic stall on an oscillating blade section

    Science.gov (United States)

    Lind, Andrew H.; Jones, Anya R.

    2016-07-01

    Wind tunnel experiments were performed on a sinusoidally oscillating NACA 0012 blade section in reverse flow. Time-resolved particle image velocimetry and unsteady surface pressure measurements were used to characterize the evolution of reverse flow dynamic stall and its sensitivity to pitch and flow parameters. The effects of a sharp aerodynamic leading edge on the fundamental flow physics of reverse flow dynamic stall are explored in depth. Reynolds number was varied up to Re = 5 × 105, reduced frequency was varied up to k = 0.511, mean pitch angle was varied up to 15∘, and two pitch amplitudes of 5∘ and 10∘ were studied. It was found that reverse flow dynamic stall of the NACA 0012 airfoil is weakly sensitive to the Reynolds numbers tested due to flow separation at the sharp aerodynamic leading edge. Reduced frequency strongly affects the onset and persistence of dynamic stall vortices. The type of dynamic stall observed (i.e., number of vortex structures) increases with a decrease in reduced frequency and increase in maximum pitch angle. The characterization and parameter sensitivity of reverse flow dynamic stall given in the present work will enable the development of a physics-based analytical model of this unsteady aerodynamic phenomenon.

  10. Spatial reliability analysis of a wind turbine blade cross section subjected to multi-axial extreme loading

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Bitsche, Robert; Blasques, José Pedro Albergaria Amaral

    2017-01-01

    properties, progressive material failure, and system reliability effects. An example analysis of reliability against material failure is demonstrated for a blade cross section. Based on the study we discuss the implications of using a system reliability approach, the effect of spatial correlation length......This paper presents a methodology for structural reliability analysis of wind turbine blades. The study introduces several novel elements by taking into account loading direction using a multiaxial probabilistic load model, considering random material strength, spatial correlation between material......, type of material degradation algorithm, and reliability methods on the system failure probability, as well as the main factors that have an influence on the reliability. (C) 2017 Elsevier Ltd. All rights reserved....

  11. TOPOLOGY AND VORTEX STRUCTURES OF A CURVING TURBINE CASCADE WITH TIP CLEARANCE ( Ⅱ )- TOPOLOGICAL FLOW PATTERN AND VORTEX STRUCTURE IN THE TRANSVERSE SECTION OF A BLADE CASCADE

    Institute of Scientific and Technical Information of China (English)

    杨庆海; 黄洪雁; 韩万今

    2002-01-01

    By means of ink trace visualization of the flows in conventional straight,positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and by appling topology theory, the topological structures and vortex structure in the transverse section of a blade cascade were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex, and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.

  12. Aerodynamic Measurements of a Variable-Speed Power-Turbine Blade Section in a Transonic Turbine Cascade

    Science.gov (United States)

    Flegel, Ashlie B.

    2014-01-01

    The purpose of this thesis is to document the impact of incidence angle and Reynolds number variations on the three-dimensional flow field and midspan loss and turning of a two-dimensional section of a variable-speed power-turbine (VSPT) rotor blade. Aerodynamic measurements were obtained in a transonic linear cascade at NASA Glenn Research Center in Cleveland, Ohio. Steady-state data were obtained for 10 incidence angles ranging from +15.8deg to -51.0deg. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12×105 to 2.12×106. Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan tota lpressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial-chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8deg and -36.7deg. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures.

  13. Spinal stab injury with retained knife blades: 51 Consecutive patients managed at a regional referral unit.

    Science.gov (United States)

    Enicker, Basil; Gonya, Sonwabile; Hardcastle, Timothy C

    2015-09-01

    Spinal stab wounds presenting with retained knife blades (RKB) are uncommon, often resulting in spinal cord injury (SCI) with catastrophic neurological consequences. The purpose of this study is to report a single unit's experience in management of this pattern of injury at this regional referral centre. Retrospective review of medical records identified 51 consecutive patients with spinal stabs presenting with a RKB at the Neurosurgery Department at Inkosi Albert Luthuli Central Hospital between January 2003 and February 2015. The data was analyzed for patient characteristics, level of the RKB, neurological status using the ASIA impairment scale, associated injuries, radiological investigations, management, hospital length of stay, complications and mortality. The mean age was 28±10.9 years (range 14-69), with 45 (88%) males (M: F=7.5:1). The median Injury Severity Score was 16 (range 4-26). RKB were located in the cervical [9,18%], thoracic [38,74%], lumbar [2,4%] and sacral [2,4%] spine. Twelve patients (24%) sustained complete SCI (ASIA A), while 21 (41%) had incomplete (ASIA B, C, D), of which 17 had features of Brown-Sequard syndrome. Eighteen (35%) patients were neurologically intact (ASIA E). There were 8 (16%) associated pneumothoraces and one vertebral artery injury. Length of hospital stay was 10±7.1 days (range 1-27). One patient (2%) died during this period. Stab injuries to the spine presenting with RKB are still prevalent in South Africa. Resources should be allocated to prevention strategies that decrease the incidence of inter-personal violence. All RKBs should be removed in the operating theatre by experienced surgeons to minimise complications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Flexible Blades for Wind Turbines

    Science.gov (United States)

    Collins, Madeline Carlisle; Macphee, David; Harris, Caleb

    2016-11-01

    Previous research has shown that windmills with flexible blades are more efficient than those with rigid blades. Flexibility offers passive pitch control, preferable to active pitch control which is costly and requires maintenance. Flexible blades morph such that the blade more closely resembles its design point at part load and over load. The lift-to-drag ratios on individual blades was investigated. A mold was designed and machined from an acrylic slab for the casting of blades with a NACA 0012 cross section. A flexible blade was cast from silicone and a rigid blade was cast from polyurethane. Each of these blades was tested in a wind tunnel, cantilever mounted, spanning the whole test section. The angle of attack was varied by rotating the mount. All tests were performed at the same wind speed. A load cell within the mount measured forces on the blade, from which the lift and drag forces were calculated. The stall point for the flexible blade occurred later than for the rigid blade, which agrees with previous research. Lift-to-drag ratios were larger for the flexible blade at all angles of attack tested. Flexible blades seem to be a viable option for passive pitch control. Future research will include different airfoil cross sections, wind speeds, and blade materials. Funding from NSF REU site Grant EEC 1358991 is greatly appreciated.

  15. Design optimization for active twist rotor blades

    Science.gov (United States)

    Mok, Ji Won

    This dissertation introduces the process of optimizing active twist rotor blades in the presence of embedded anisotropic piezo-composite actuators. Optimum design of active twist blades is a complex task, since it involves a rich design space with tightly coupled design variables. The study presents the development of an optimization framework for active helicopter rotor blade cross-sectional design. This optimization framework allows for exploring a rich and highly nonlinear design space in order to optimize the active twist rotor blades. Different analytical components are combined in the framework: cross-sectional analysis (UM/VABS), an automated mesh generator, a beam solver (DYMORE), a three-dimensional local strain recovery module, and a gradient based optimizer within MATLAB. Through the mathematical optimization problem, the static twist actuation performance of a blade is maximized while satisfying a series of blade constraints. These constraints are associated with locations of the center of gravity and elastic axis, blade mass per unit span, fundamental rotating blade frequencies, and the blade strength based on local three-dimensional strain fields under worst loading conditions. Through pre-processing, limitations of the proposed process have been studied. When limitations were detected, resolution strategies were proposed. These include mesh overlapping, element distortion, trailing edge tab modeling, electrode modeling and foam implementation of the mesh generator, and the initial point sensibility of the current optimization scheme. Examples demonstrate the effectiveness of this process. Optimization studies were performed on the NASA/Army/MIT ATR blade case. Even though that design was built and shown significant impact in vibration reduction, the proposed optimization process showed that the design could be improved significantly. The second example, based on a model scale of the AH-64D Apache blade, emphasized the capability of this framework to

  16. Finite element analysis of the cross-section of wind turbine blades; a comparison between shell and 2D-solid models

    DEFF Research Database (Denmark)

    Pardo, D.; Branner, K.

    2005-01-01

    A very detailed 2D-solid finite element model is developed representing the load carrying box girder of a wind turbine blade. Using typical geometrical values for the girder dimensions and public available material data, the overall cross-sectional behaviour is analysed for a simple compressive...

  17. The use of cross-section warping functions in composite rotor blade analysis

    Science.gov (United States)

    Kosmatka, J. B.

    1992-01-01

    During the contracted period, our research was concentrated into three areas. The first was the development of an accurate and a computationally efficient method for predicting the cross-section warping functions in an arbitrary cross-section composed of isotropic and/or anisotropic materials. The second area of research was the development of a general higher-order one-dimensional theory for anisotropic beams. The third area of research was the development of an analytical model for assessing the extension-bend-twist coupling behavior of nonhomogeneous anisotropic beams with initial twist. In the remaining six chapters of this report, the three different research areas and associated sub-research areas are covered independently including separate introductions, theoretical developments, numerical results, and references.

  18. Investigation of Dynamic Aerodynamics and Control of Wind Turbine Sections Under Relevant Inflow/Blade Attitude Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Naughton, Jonathan W. [University of Wyoming

    2014-08-05

    The growth of wind turbines has led to highly variable loading on the blades. Coupled with the relative reduced stiffness of longer blades, the need to control loading on the blades has become important. One method of controlling loads and maximizing energy extraction is local control of the flow on the wind turbine blades. The goal of the present work was to better understand the sources of the unsteady loading and then to control them. This is accomplished through an experimental effort to characterize the unsteadiness and the effect of a Gurney flap on the flow, as well as an analytical effort to develop control approaches. It was planned to combine these two efforts to demonstrate control of a wind tunnel test model, but that final piece still remains to be accomplished.

  19. Investigation of Advanced Counterrotation Blade Configuration Concepts for High Speed Turboprop Systems. Task 3: Advanced Fan Section Grid Generator Final Report and Computer Program User's Manual

    Science.gov (United States)

    Crook, Andrew J.; Delaney, Robert A.

    1991-01-01

    A procedure is studied for generating three-dimensional grids for advanced turbofan engine fan section geometries. The procedure constructs a discrete mesh about engine sections containing the fan stage, an arbitrary number of axisymmetric radial flow splitters, a booster stage, and a bifurcated core/bypass flow duct with guide vanes. The mesh is an h-type grid system, the points being distributed with a transfinite interpolation scheme with axial and radial spacing being user specified. Elliptic smoothing of the grid in the meridional plane is a post-process option. The grid generation scheme is consistent with aerodynamic analyses utilizing the average-passage equation system developed by Dr. John Adamczyk of NASA Lewis. This flow solution scheme requires a series of blade specific grids each having a common axisymmetric mesh, but varying in the circumferential direction according to the geometry of the specific blade row.

  20. Effects of geometric non-linearity on energy release rates in a realistic wind turbine blade cross section

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Bitsche, Robert; Belloni, Federico

    2015-01-01

    efficient numerical slice modelling approach, the Virtual Crack Closure Technique (VCCT) is used to compute Mode-I and Mode-II ERRs induced by bi-axial bending. Generic critical loading directions are identified; these may have far-reaching consequences for blade design, analysis and testing....

  1. Aerodynamic Measurements of a Variable-Speed Power-Turbine Blade Section in a Transonic Turbine Cascade at Low Inlet Turbulence

    Science.gov (United States)

    Flegel-McVetta, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2013-01-01

    Aerodynamic measurements obtained in a transonic linear cascade were used to assess the impact of large incidence angle and Reynolds number variations on the 3-D flow field and midspan loss and turning of a 2-D section of a variable-speed power-turbine (VSPT) rotor blade. Steady-state data were obtained for ten incidence angles ranging from +15.8 deg to -51.0 deg. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12×10(exp 5) to 2.12×10(exp 6). Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan total-pressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8 deg and -36.7 deg. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures. Tests were conducted in the NASA Glenn Transonic Turbine Blade Cascade Facility. The measurements reflect strong secondary flows associated with the high aerodynamic loading levels at large positive incidence angles and an increase in loss levels with decreasing Reynolds number. The secondary flows decrease with negative incidence as the blade becomes unloaded. Transitional flow is admitted in this low inlet turbulence dataset, making it a challenging CFD test case. The dataset will be used to advance understanding of the aerodynamic

  2. Production of short straight sections hits 100 units

    CERN Multimedia

    2005-01-01

    The 100th short straight section for the Large Hadron Collider was assembled at CERN at the beginning of April. These units combine superconducting quadrupoles and other multipole corrector magnets, housed in their cryostats, which are used to guide, focus and fine-tune the beam in the LHC. Building 904, where the 474 short straight sections are being assembled, is often called "Lego Land" by the workers, with a touch of humor and pride because of the wide variety of these sets of magnets and cryostats .

  3. Constructal blade shape in nanofluids

    Directory of Open Access Journals (Sweden)

    Bai Chao

    2011-01-01

    Full Text Available Abstract Blade configuration of nanofluids has been proven to perform much better than dispersed configuration for some heat conduction systems. The analytical analysis and numerical calculation are made for the cylinder--shaped and regular-rectangular-prism--shaped building blocks of the blade-configured heat conduction systems (using nanofluids as the heat conduction media to find the optimal cross-sectional shape for the nanoparticle blade under the same composing materials, composition ratio, volumetric heat generation rate, and total building block volume. The regular-triangular-prism--shaped blade has been proven to perform better than all the other three kinds of blades, namely, the regular-rectangular-prism--shaped blade, the regular-hexagonal-prism--shaped blade, and the cylinder--shaped blade. Thus, the regular-triangular-prism--shaped blade is selected as the optimally shaped blade for the two kinds of building blocks that are considered in this study. It is also proven that the constructal cylinder--regular-triangular-prism building block performs better than the constructal regular-rectangular-prism--regular-triangular-prism building block.

  4. 3 CFR - Designation of Officers of the United States Section, International Boundary and Water Commission...

    Science.gov (United States)

    2010-01-01

    ..., International Boundary and Water Commission, United States and Mexico To Act as the Commissioner of the United... Designation of Officers of the United States Section, International Boundary and Water Commission, United... of the United States Section, International Boundary and Water Commission, United......

  5. Design of Wind Turbine Blades

    DEFF Research Database (Denmark)

    2016-01-01

    In this section the research program framework for European PhD network MARE-WINT is presented, particularly the technology development work focussing on reliability/maintenance and the models describing multi-body fluid structure interaction for the Rotor Blade structure. In order to give a cont...... a context for the effort undertaken by the individual researchers this section gives a general background for Wind Turbine blades identifying the trends and issues of importance for these structures as well as concepts for “smarter” blades that address these issues.......In this section the research program framework for European PhD network MARE-WINT is presented, particularly the technology development work focussing on reliability/maintenance and the models describing multi-body fluid structure interaction for the Rotor Blade structure. In order to give...

  6. Structural optimization of wind turbine rotor blades by multilevel sectional/multibody/3D-FEM analysis

    DEFF Research Database (Denmark)

    Bottasso, C. L.; Campagnolo, F.; Croce, A.

    2014-01-01

    level. At first, a "coarse"-level constrained design optimization is performed by using a 1D spatial geometrically exact beam model for aero-servo-elastic multibody analysis and load calculation, integrated with a 2D FEM cross sectional model for stress/strain analysis, and the evaluation of the 1D...

  7. 75 FR 18238 - United States Section; Final Environmental Impact Statement, Flood Control Improvements and...

    Science.gov (United States)

    2010-04-09

    ..., Flood Control Improvements and Partial Levee Relocation, United States Section, International Boundary and Water Commission (USIBWC) Presidio Flood Control Project (FCP), Presidio, TX AGENCY: United States... potential consequences of each action alternative in reference to flood control improvements. Following...

  8. Prismatic Blade Measuring on a Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Stech J.

    2013-04-01

    Full Text Available The results from measurement on the straight blade cascade are presented in the paper. The cascade is placed at the outlet of wind tunnel in ŠKODA POWER experimental base. The results in the form of velocity and loss fields behind blade cascade as well as the distribution of the loss coefficient in selected cross-section are evaluated.

  9. Torsional Performance of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Berring, Peter; Branner, Kim; Berggreen, Christian

    2007-01-01

    The complete 3D static responses of two different eight meter long wind turbine blade sections were tested. To experimentally investigate the 3D response, an advanced 3D digital optical deformation measuring system (ARAMIS 2M and 4M) was applied in this work. This system measures the full......-field displacements (ux, uy and uz) of the blade surface. A least squares algorithm was developed, which fits a plane through each deformed cross section, and defines a single set of displacements and rotations (three displacements and rotations) per cross section. This least squares algorithm was also used...... to accommodate problems with a flexible boundary condition by determining the displacements and rotations for a cross section near the boundary. These displacements and rotations are subtracted from all other cross sections along the blade and thereby making the blade section fully fixed at the chosen cross...

  10. Application of Circulation Controlled Blades for Vertical Axis Wind Turbines

    OpenAIRE

    Shires, A.; Kourkoulis, V

    2013-01-01

    The blades of a vertical axis wind turbine (VAWT) rotor see an inconsistent angle of attack through its rotation. Consequently, VAWT blades generally use symmetrical aerofoils with a lower lift-to-drag ratio than cambered aerofoils tailored to maximise horizontal axis wind turbine rotor performance. This paper considers the feasibility of circulation controlled (CC) VAWT blades, using a tangential air jet to provide lift and therefore power augmentation. However CC blade sections require a hi...

  11. Innovative design approaches for large wind turbine blades : final report.

    Energy Technology Data Exchange (ETDEWEB)

    2004-05-01

    The goal of the Blade System Design Study (BSDS) was investigation and evaluation of design and manufacturing issues for wind turbine blades in the one to ten megawatt size range. A series of analysis tasks were completed in support of the design effort. We began with a parametric scaling study to assess blade structure using current technology. This was followed by an economic study of the cost to manufacture, transport and install large blades. Subsequently we identified several innovative design approaches that showed potential for overcoming fundamental physical and manufacturing constraints. The final stage of the project was used to develop several preliminary 50m blade designs. The key design impacts identified in this study are: (1) blade cross-sections, (2) alternative materials, (3) IEC design class, and (4) root attachment. The results show that thick blade cross-sections can provide a large reduction in blade weight, while maintaining high aerodynamic performance. Increasing blade thickness for inboard sections is a key method for improving structural efficiency and reducing blade weight. Carbon/glass hybrid blades were found to provide good improvements in blade weight, stiffness, and deflection when used in the main structural elements of the blade. The addition of carbon resulted in modest cost increases and provided significant benefits, particularly with respect to deflection. The change in design loads between IEC classes is quite significant. Optimized blades should be designed for each IEC design class. A significant portion of blade weight is related to the root buildup and metal hardware for typical root attachment designs. The results show that increasing the number of blade fasteners has a positive effect on total weight, because it reduces the required root laminate thickness.

  12. The Magnitude and Time Course of Muscle Cross-section Decrease in Intensive Care Unit Patients.

    Science.gov (United States)

    Ten Haaf, Dianne; Hemmen, Bea; van de Meent, Henk; BovendʼEerdt, Thamar J H

    2017-09-01

    Bedriddenness and immobilization of patients at an intensive care unit may result in muscle atrophy and devaluation in quality of life. The exact effect of immobilization on intensive care unit patients is not known. The aim of this study was to investigate the magnitude and time course of muscle cross-section decrease in acute critically ill patients admitted to the intensive care unit. An observational pilot study was performed in intensive care unit patients. Data of bilateral ultrasound muscle cross-section measurements of the knee extensors and the elbow flexors were collected. Thirty-four intensive care unit patients were included in this study; data are presented from 14 patients who were measured at least three times. Repeated measures analysis of variance shows a significant decrease in muscle cross-section over time (F1,13 = 80.40, P ≤ 0.001).The decrease in muscle cross-section of the arms was significantly higher (F1,13 = 5.38, P = 0.037) than the decrease of the legs. Four weeks after intensive care unit admission, the muscle cross-section decrease had not reached an asymptote yet. The muscle cross-section decrease in bedridden intensive care unit patients is significant for a time of 2 to 4 weeks. The decrease in muscle cross-section of the arms is greater than the decrease of the legs.

  13. 75 FR 23563 - Delegation of Certain Functions Under Section 104(g) of the United States-India Peaceful Atomic...

    Science.gov (United States)

    2010-05-04

    ...;#0; ] Memorandum of April 27, 2010 Delegation of Certain Functions Under Section 104(g) of the United... of the United States, including section 301 of title 3, United States Code, I hereby delegate to you the functions and authority conferred upon the President by section 104(g) of the United...

  14. Energy harvesting to power sensing hardware onboard wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Clinton P [Los Alamos National Laboratory; Schichting, Alexander D [Los Alamos National Laboratory; Quellette, Scott [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Park, Gyuhae [Los Alamos National Laboratory

    2009-10-05

    Wind turbines are becoming a larger source of renewable energy in the United States. However, most of the designs are geared toward the weather conditions seen in Europe. Also, in the United States, manufacturers have been increasing the length of the turbine blades, often made of composite materials, to maximize power output. As a result of the more severe loading conditions in the United States and the material level flaws in composite structures, blade failure has been a more common occurrence in the U.S. than in Europe. Therefore, it is imperative that a structural health monitoring system be incorporated into the design of the wind turbines in order to monitor flaws before they lead to a catastrophic failure. Due to the rotation of the turbine and issues related to lightning strikes, the best way to implement a structural health monitoring system would be to use a network of wireless sensor nodes. In order to provide power to these sensor nodes, piezoelectric, thermoelectric and photovoltaic energy harvesting techniques are examined on a cross section of a CX-100 wind turbine blade in order to determine the feasibility of powering individual nodes that would compose the sensor network.

  15. Wind Turbine Blade

    DEFF Research Database (Denmark)

    2010-01-01

    The invention relates to a blade for a wind turbine, particularly to a blade that may be produced by an advanced manufacturing process for producing a blade with high quality structural components. Particularly, the structural components, which are preferably manufactured from fibre reinforced...

  16. Turbomachine blade assembly

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Crespo, Andres Jose

    2016-11-01

    Embodiments of the present disclosure include a system comprising a turbomachine blade assembly having a blade portion, a shank portion, and a mounting portion, wherein the blade portion, the shank portion, and the mounting portion comprise a first plurality of plies extending from a tip of the airfoil to a base of the dovetail.

  17. Turbomachine blade reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Crespo, Andres Jose

    2016-09-06

    Embodiments of the present disclosure include a system having a turbomachine blade segment including a blade and a mounting segment coupled to the blade, wherein the mounting segment has a plurality of reinforcement pins laterally extending at least partially through a neck of the mounting segment.

  18. Wind Turbine Blade

    DEFF Research Database (Denmark)

    2010-01-01

    The invention relates to a blade for a wind turbine, particularly to a blade that may be produced by an advanced manufacturing process for producing a blade with high quality structural components. Particularly, the structural components, which are preferably manufactured from fibre reinforced...

  19. Blade reliability collaborative :

    Energy Technology Data Exchange (ETDEWEB)

    Ashwill, Thomas D.; Ogilvie, Alistair B.; Paquette, Joshua A.

    2013-04-01

    The Blade Reliability Collaborative (BRC) was started by the Wind Energy Technologies Department of Sandia National Laboratories and DOE in 2010 with the goal of gaining insight into planned and unplanned O&M issues associated with wind turbine blades. A significant part of BRC is the Blade Defect, Damage and Repair Survey task, which will gather data from blade manufacturers, service companies, operators and prior studies to determine details about the largest sources of blade unreliability. This report summarizes the initial findings from this work.

  20. 75 FR 27155 - Delegation of Authority Relating To Certain Functions Under Section 201 (B) of the United States...

    Science.gov (United States)

    2010-05-14

    ... Certain Functions Under Section 201 (B) of the United States- india Nuclear Cooperation Approval And... section 301 of title 3, United States Code, I hereby delegate to you the certification and reporting functions conferred upon the President by section 201 (b) of the United States-India Nuclear...

  1. 75 FR 13427 - Delegation of Certain Functions Under Section 204(c) of the United States-India Nuclear...

    Science.gov (United States)

    2010-03-22

    ... Functions Under Section 204(c) of the United States-India Nuclear Cooperation Approval and Nonproliferation... President by the Constitution and the laws of the United States of America, including section 301 of title 3, United States Code, I hereby delegate to you the functions conferred upon the President by section...

  2. 78 FR 37921 - Delegation of Reporting Functions Specified in Section 491 of Title 10, United State Code

    Science.gov (United States)

    2013-06-24

    ... Specified in Section 491 of Title 10, United States Code Notice of June 20, 2013--Continuation of the... Reporting Functions Specified in Section 491 of Title 10, United State Code Memorandum for the Secretary of... of America, including section 301 of title 3 of the United States Code, I hereby delegate to you...

  3. 78 FR 37923 - Delegation of Reporting Functions Specified in Section 491 of Title 10, United State Code

    Science.gov (United States)

    2013-06-24

    ... Specified in Section 491 of Title 10, United States Code Notice of June 20, 2013--Continuation of the... Reporting Functions Specified in Section 491 of Title 10, United State Code Memorandum for the Secretary of... of America, including section 301 of title 3 of the United States Code, I hereby delegate to you...

  4. Blade-element/momentum theory

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær

    2016-01-01

    Although there exists a large variety of methods for predicting performance and loadings of wind turbines, the only approach used today by wind turbine manufacturers is based on the blade-element/momentum (BEM) theory by Glauert (Aerodynamic theory. Springer, Berlin, pp. 169-360, 1935). A basic...... assumption in the BEM theory is that the flow takes place in independent stream tubes and that the loading is determined from two-dimensional sectional airfoil characteristics....

  5. Wind turbine blade waste in 2050.

    Science.gov (United States)

    Liu, Pu; Barlow, Claire Y

    2017-04-01

    Wind energy has developed rapidly over the last two decades to become one of the most promising and economically viable sources of renewable energy. Although wind energy is claimed to provide clean renewable energy without any emissions during operation, but it is only one side of the coin. The blades, one of the most important components in the wind turbines, made with composite, are currently regarded as unrecyclable. With the first wave of early commercial wind turbine installations now approaching their end of life, the problem of blade disposal is just beginning to emerge as a significant factor for the future. This paper is aimed at discovering the magnitude of the wind turbine blade waste problem, looking not only at disposal but at all stages of a blade's lifecycle. The first stage of the research, the subject of this paper, is to accurately estimate present and future wind turbine blade waste inventory using the most recent and most accurate data available. The result will provide a solid reference point to help the industry and policy makers to understand the size of potential environmental problem and to help to manage it better. This study starts by estimating the annual blade material usage with wind energy installed capacity and average blade weight. The effect of other waste contributing factors in the full lifecycle of wind turbine blades is then included, using industrial data from the manufacturing, testing and in-service stages. The research indicates that there will be 43 million tonnes of blade waste worldwide by 2050 with China possessing 40% of the waste, Europe 25%, the United States 16% and the rest of the world 19%. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  6. Wireless Inductive Power Device Suppresses Blade Vibrations

    Science.gov (United States)

    Morrison, Carlos R.; Provenza, Andrew J.; Choi, Benjamin B.; Bakhle, Milind A.; Min, James B.; Stefko, George L.; Duffy, Kirsten P.; Fougers, Alan J.

    2011-01-01

    Vibration in turbomachinery can cause blade failures and leads to the use of heavier, thicker blades that result in lower aerodynamic efficiency and increased noise. Metal and/or composite fatigue in the blades of jet engines has resulted in blade destruction and loss of lives. Techniques for suppressing low-frequency blade vibration, such as gtuned circuit resistive dissipation of vibratory energy, h or simply "passive damping," can require electronics incorporating coils of unwieldy dimensions and adding unwanted weight to the rotor. Other approaches, using vibration-dampening devices or damping material, could add undesirable weight to the blades or hub, making them less efficient. A wireless inductive power device (WIPD) was designed, fabricated, and developed for use in the NASA Glenn's "Dynamic Spin Rig" (DSR) facility. The DSR is used to simulate the functionality of turbomachinery. The relatively small and lightweight device [10 lb (approx.=4.5 kg)] replaces the existing venerable and bulky slip-ring. The goal is the eventual integration of this technology into actual turbomachinery such as jet engines or electric power generators, wherein the device will facilitate the suppression of potentially destructive vibrations in fan blades. This technology obviates slip rings, which require cooling and can prove unreliable or be problematic over time. The WIPD consists of two parts: a remote element, which is positioned on the rotor and provides up to 100 W of electrical power to thin, lightweight piezoelectric patches strategically placed on/in fan blades; and a stationary base unit that wirelessly communicates with the remote unit. The base unit supplies inductive power, and also acts as an input and output corridor for wireless measurement, and active control command to the remote unit. Efficient engine operation necessitates minimal disturbance to the gas flow across the turbine blades in any effort to moderate blade vibration. This innovation makes it

  7. An experimental investigation of two 15 percent-scale wind tunnel fan-blade designs

    Science.gov (United States)

    Signor, David B.

    1988-01-01

    An experimental 3-D investigation of two fan-blade designs was conducted. The fan blades tested were 15 percent-scale models of blades to be used in the fan drive of the National Full-Scale Aerodynamic Complex at NASA Ames Research Center. NACA 65- and modified NACA 65-series sections incorporated increased thickness on the upper surface, between the leading edge and the one-half-chord position. Twist and taper were the same for both blade designs. The fan blades with modified 65-series sections were found to have an increased stall margin when they were compared with the unmodified blades.

  8. Comparison of blade-strike modeling results with empirical data

    Energy Technology Data Exchange (ETDEWEB)

    Ploskey, Gene R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carlson, Thomas J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2004-03-01

    This study is the initial stage of further investigation into the dynamics of injury to fish during passage through a turbine runner. As part of the study, Pacific Northwest National Laboratory (PNNL) estimated the probability of blade strike, and associated injury, as a function of fish length and turbine operating geometry at two adjacent turbines in Powerhouse 1 of Bonneville Dam. Units 5 and 6 had identical intakes, stay vanes, wicket gates, and draft tubes, but Unit 6 had a new runner and curved discharge ring to minimize gaps between the runner hub and blades and between the blade tips and discharge ring. We used a mathematical model to predict blade strike associated with two Kaplan turbines and compared results with empirical data from biological tests conducted in 1999 and 2000. Blade-strike models take into consideration the geometry of the turbine blades and discharges as well as fish length, orientation, and distribution along the runner. The first phase of this study included a sensitivity analysis to consider the effects of difference in geometry and operations between families of turbines on the strike probability response surface. The analysis revealed that the orientation of fish relative to the leading edge of a runner blade and the location that fish pass along the blade between the hub and blade tip are critical uncertainties in blade-strike models. Over a range of discharges, the average prediction of injury from blade strike was two to five times higher than average empirical estimates of visible injury from shear and mechanical devices. Empirical estimates of mortality may be better metrics for comparison to predicted injury rates than other injury measures for fish passing at mid-blade and blade-tip locations.

  9. Multiple piece turbine rotor blade

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Keith D.; Plank, William L.

    2016-07-19

    A spar and shell turbine rotor blade with a spar and a tip cap formed as a single piece, the spar includes a bottom end with dovetail or fir tree slots that engage with slots on a top end of a root section, and a platform includes an opening on a top surface for insertion of the spar in which a shell made from an exotic high temperature resistant material is secured between the tip cap and the platform. The spar is tapered to form thinner walls at the tip end to further reduce the weight and therefore a pulling force due to blade rotation. The spar and tip cap piece is made from a NiAL material to further reduce the weight and the pulling force.

  10. Blade Runner forever

    DEFF Research Database (Denmark)

    Dickson, Thomas

    2003-01-01

    Om de påfaldende ligheder mellem scenografien til Ridley Scotts 'Blade Runner'og de faktuelle bymiljøer i nutidens Tokyo.......Om de påfaldende ligheder mellem scenografien til Ridley Scotts 'Blade Runner'og de faktuelle bymiljøer i nutidens Tokyo....

  11. Composite wind turbine blades

    Science.gov (United States)

    Ong, Cheng-Huat

    Researchers in wind energy industry are constantly moving forward to develop higher efficiency wind turbine. One major component for wind turbine design is to have cost effective wind turbine blades. In addition to correct aerodynamic shape and blade geometry, blade performance can be enhanced further through aero-elastic tailoring design and material selections. An analytical tool for blade design has been improved and validated. This analytical tool is utilized to resolve issues related to elastic tailoring design. The investigation looks into two major issues related to the design and fabrication of a bend-twist-coupled blade. Various design parameters for a blade such as materials, laminate lay-up, skin thickness, ply orientation, internal spar, etc. have been examined for designing a bend-twist-coupled blade. The parametric study indicates that the critical design parameters are the ply material, the ply orientation, and the volume fraction ratio between the anisotropic layers and orthotropic layers. To produce a blade having the bend-twist coupling characteristics, the fiber lay-ups at the top and bottom skins of the blade must have a "mirror" lay-up in relation to the middle plane of the blade. Such lay-up causes fiber discontinuation at the seam. The joint design at the seam is one major consideration in fabricating a truly anisotropic blade. A new joint design was proposed and tensile failure tests were carried out for both the old and new joint designs. The tests investigated the effects of different types of joint designs, the laminate lay-up at the joints, and the stacking sequence of the joint retention strength. A major component of a wind turbine blade, D-spar, was designed to maximum coupling. Two D-spars were then fabricated using the new joint design; one of them was subjected to both static and modal testings. Traditionally, wind turbine blades are made of low cost glass material; however, carbon fibers are proposed as alternative material. Our

  12. Blade Group Fatigue Life Calculation under Resonant Stresses

    Directory of Open Access Journals (Sweden)

    Zlatko Petreski

    2017-02-01

    Full Text Available The results of the simulations of the blade group resonant stresses in a FE environment and fatigue life calculation are presented in this paper. Numerical calculation for determination of natural frequencies, mode shapes and dynamic stresses, based on FEM and NISA package is used. Analyses are made on the blade group with three blades with rectangular cross section and typical turbine blades with taper, pretwist and asymmetric airfoil as well. The influence of the position of the lacing wire on the resonant stresses is analyzed. Three-dimensional finite element models of the blade group are made by using twenty node isoparametric solid elements. The number of degrees of freedom is different for each model (more than 30000 DOF. The fatigue life and consequent life prediction according the stress load history of the blades is made. The results of the investigation are given in tables and graphics.

  13. Dendritic Structure Analysis of CMSX-4 Cored Turbine Blades Roots

    Directory of Open Access Journals (Sweden)

    Krawczyk J.

    2016-06-01

    Full Text Available The microstructure of as-cast cored turbine blades roots, made of the single-crystal CMSX-4 nickel-based superalloy was investigated. Analysed blades were obtained by directional solidification technique in the industrial ALD Bridgman induction furnace. The investigations of the microstructure of blades roots were performed using SEM and X-ray techniques including diffraction topography with the use of Auleytner method. Characteristic shapes of dendrites with various arrangement were observed on the SEM images taken from the cross-sections, made transversely to the main blades axis. The differences in quality of the structure in particular areas of blades roots were revealed. Based on the results, the influence of cooling bores on blades root structure was analysed and the changes in the distribution and geometry of cooling bores were proposed.

  14. Effects of Blade Discharge Angle, Blade Number and Splitter Blade Length on Deep Well Pump Performance

    Directory of Open Access Journals (Sweden)

    E. Korkmaz

    2017-01-01

    Full Text Available Impellers with splitter blades are used for pumps and compressors in the design of turbomachines. Design parameters such as the number of blades, blade discharge angle and impeller discharge diameter impact affect pump performance and energy consumption. In this study, the effect of the number of blades (z=5, 6, and 7, blade discharge angles (β2b=25, and β2b=35 and splitter blade lengths (40, 55, 70, and 85% of the main blade length on Deep Well Pump (DWP performance has been studied experimentally. In the experiments, pump casing, blade inlet angle, blade thickness, blade width and impeller inlet and discharge diameters have been kept fixed while other parameters such as the number of blades, blade discharge angles and splitter blade lengths have been allowed to vary. As a result of the experimental study, the highest efficiency of all the impellers for best efficiency point (b.e.p has been obtained on the impeller with the number of blades z=6, blade discharge angle 2b=25 and 85% splitter blade addition compared to impellers without splitter blades.

  15. Optimization Method for Girder of Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Yuqiao Zheng

    2014-01-01

    Full Text Available This paper presents a recently developed numerical multidisciplinary optimization method for design of wind turbine blade. The objective was the highest possible blade weight under specified atmospheric conditions, determined by the design giving girder layer and location parameter. Wind turbine blade on box-section beams girder is calculated by ply thickness, main girder and trailing edge. In this study, a realistic 30 m blade from a 1.2 MW wind turbine model of blade girder parameters is established. The optimization evolves a structure which transforms along the length of the blade, changing from a design with spar caps at the maximum thickness and a trailing edge mass to a design with spar caps toward the tip. In addition, the cross-section structural properties and the modal characteristics of a 62 m rotor blade were predicted by the developed beam finite element. In summary, these findings indicate that the conventional structural layout of a wind turbine blade is suboptimal under the static load conditions, suggesting an opportunity to reduce blade weight and cost.

  16. Methodology for Structural Integrity Analysis of Gas Turbine Blades

    Directory of Open Access Journals (Sweden)

    Tiago de Oliveira Vale

    2012-03-01

    Full Text Available One of the major sources of stress arising in turbomachinery blades are the centrifugal loads acting at any section of the airfoil. Accounting for this phenomenon stress evaluation of the blade attachment region in the disc has to be performed in order to avoid blade failure. Turbomachinery blades are generally twisted, and the cross section area varies from the root of the blade to the tip. The blade root shape at the attachment region is of great concern. Stress concentrations are predictable at this contact region. In this paper, a finite element model has been created for the purpose of assessing stress at the joint region connecting the blade to the disc slot. Particular attention was paid to the geometric modeling of the "fir-tree" fixing, which is now used in the majority of gas turbine engines. This study has been performed using the commercial software ANSYS 13.0. The disc and blade assembly are forced to move with a certain rotational velocity. Contact connections are predicted on the common faces of the blade and on the disc at the root. Solutions can be obtained to allow the evaluation of stresses. Results can be compared with the mechanical properties of the adopted material.

  17. 14 CFR 27.661 - Rotor blade clearance.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rotor blade clearance. 27.661 Section 27.661 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... clearance. There must be enough clearance between the rotor blades and other parts of the structure...

  18. 14 CFR 29.661 - Rotor blade clearance.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rotor blade clearance. 29.661 Section 29.661 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT... clearance. There must be enough clearance between the rotor blades and other parts of the structure...

  19. Blade attachment assembly

    Science.gov (United States)

    Garcia-Crespo, Andres Jose; Delvaux, John McConnell; Miller, Diane Patricia

    2016-05-03

    An assembly and method for affixing a turbomachine rotor blade to a rotor wheel are disclosed. In an embodiment, an adaptor member is provided disposed between the blade and the rotor wheel, the adaptor member including an adaptor attachment slot that is complementary to the blade attachment member, and an adaptor attachment member that is complementary to the rotor wheel attachment slot. A coverplate is provided, having a coverplate attachment member that is complementary to the rotor wheel attachment slot, and a hook for engaging the adaptor member. When assembled, the coverplate member matingly engages with the adaptor member, and retains the blade in the adaptor member, and the assembly in the rotor wheel.

  20. Construction of low-cost, Mod-OA wood composite wind turbine blades

    Science.gov (United States)

    Lark, R. F.

    1983-01-01

    Two sixty-foot, low-cost, wood composite blades for service on 200 kW Mod-OA wind turbines were constructed. The blades were constructed of epoxy resin-bonded Douglas fir veneers for the leading edge sections, and paper honeycombcored, birch plywood faced panels for the afterbody sections. The blades were joined to the wind turbine hub by epoxy resin-bonded steel load take-off studs embedded into the root end of the blades. The blades were installed on the 200 kW Mod-OA wind turbine facility at Kahuku, Hawaii, The blades completed nearly 8,000 hours of operation over an 18 month period at an average power of 150 kW prior to replacement with another set of wood composite blades. The blades were replaced because of a corrosion failure of the steel shank on one stud. Inspections showed that the wood composite structure remained in excellent condition.

  1. Dynamic Response of Flexible Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Yu-qiao Zheng

    2013-07-01

    Full Text Available Aiming at the non-stationary and stall flutter problems of wind turbine blade caused by transient load fluctuations, the dynamic properties of wind turbine were studied, the blade was simplify to a cantilever beam in case of the action of shear deformation and cross section rotating effect were considered in this analysis, equations of the blade were established based on D'Alemberts' principle and the principle of virtual displacement. The dynamic response of the wind turbine was solved by using the finite element method under the transient load environment. A 29.2 m rotor blade, previously reported in specialized literature, was chosen as a case study to validate dynamic behaviour predicted by a Timoshenko beam model. It is concluded that despite its simplicity, The cross-sectional shear-deformation  has great influence on  dynamic response of the blade.Dynamic model is sufficiently accurate to serve as a design tool for the recursive analyses required during design and optimization stages of wind turbines using only readily available computational tools.

  2. Blade Testing Trends (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Desmond, M.

    2014-08-01

    As an invited guest speaker, Michael Desmond presented on NREL's NWTC structural testing methods and capabilities at the 2014 Sandia Blade Workshop held on August 26-28, 2014 in Albuquerque, NM. Although dynamometer and field testing capabilities were mentioned, the presentation focused primarily on wind turbine blade testing, including descriptions and capabilities for accredited certification testing, historical methodology and technology deployment, and current research and development activities.

  3. A method to estimate wind turbine blade damage and to design damage-resilient blades

    Science.gov (United States)

    Fiore, Giovanni

    Wind turbine blades are affected by continuous impacts with airborne particles that deteriorate the blade surface and yield to a drop in output power. Based on the climatic conditions and geographic locations of a given wind farm, multiple types of particles are observed in air. The present study focuses on simulating the impact of four types of particles, namely insects, sand grains, hailstones, and rain drops with the blade surface. A numerical inviscid flowfield code, coupled with a particle position predictor code was used. Upon impact, the damaging effect to the blade surface was evaluated. Each type of particle was associated with a damage mode, which depends on the mass, size, and hardness of the particle. It was found that insects strike and adhere to the blade in a region close to the leading edge. On the other hand, it was seen that sand grains promote erosion just downstream of the leading edge, where local velocity reaches a maximum and the impact angle is shallow. Moreover, particles such as rain drops are associated with fatigue and erosion at the very leading edge and on the upper side of the blade section. Finally, hailstones promote delamination and fatigue in the composite panels of the blade surface. Photographic evidence of damaged blade surfaces was used in the present research as a comparison with the simulations performed for various types of particle and different initial conditions. Based on such observations, a theorization of the damage pattern and evolution was proposed. Finally, given a set of well-established blade section geometries, such as the Delft University and NREL S airfoil families, a comparison of airfoil damage fitness was proposed and possible means of shape optimization were discussed. The investigation of blade geometry features to mitigate damage was performed. Based on previous results, it was argued that a viable blade section optimization may be performed for the lightest and smallest particles considered in the study

  4. 76 FR 22003 - Delegation of Functions and Authority Under Sections 315 and 325 of Title 32, United States Code

    Science.gov (United States)

    2011-04-20

    ... 325 of Title 32, United States Code Memorandum for the Secretary of Defense By the authority vested in... 301 of title 3, United States Code, I hereby delegate to you: (a) the functions and authority of the President contained in section 315 of title 32, United States Code, to permit a commissioned officer of...

  5. Improved simulation design factors for unconventional crude vacuum units : cracked gas make and stripping section performance

    Energy Technology Data Exchange (ETDEWEB)

    Remesat, D. [Koch-Glitsch Canada LP, Calgary, AB (Canada)

    2008-10-15

    Operating data for unconventional heavy oil vacuum crude units were reviewed in order to optimize the design of vacuum columns. Operational data from heavy crude vacuum units operating with stripping and velocity were used to investigate the application of a proven vacuum distillation tower simulation topology designed for use with heavy oil and bitumen upgrader feeds. Design factors included a characterization of the crude oils or bitumens processed in the facility; the selection of thermodynamic models; and the non-equilibrium simulation topology. Amounts of generated cracked gas were calculated, and entrainment and stripping section performance was evaluated. Heater designs for ensuring the even distribution of heat flux were discussed. Data sets from vacuum units processing crude oils demonstrated that the amount of offgas flow increased as the transfer line temperature increased. The resulting instability caused increased coke generation and light hydrocarbon formation. Results also indicated that overhead vacuum ejector design and size as well as heat transfer capabilities of quench and pumparound zones must be considered when designing vacuum column units. Steam stripping lowered hydrocarbon partial pressure to allow materials to boil at lower temperatures. It was concluded that setting appropriate entrainment values will ensure the accuracy of sensitivity analyses for transfer line designs, inlet feed devices, and wash bed configurations. 9 refs., figs.

  6. Structural health monitoring of wind turbine blades

    Science.gov (United States)

    Rumsey, Mark A.; Paquette, Joshua A.

    2008-03-01

    As electric utility wind turbines increase in size, and correspondingly, increase in initial capital investment cost, there is an increasing need to monitor the health of the structure. Acquiring an early indication of structural or mechanical problems allows operators to better plan for maintenance, possibly operate the machine in a de-rated condition rather than taking the unit off-line, or in the case of an emergency, shut the machine down to avoid further damage. This paper describes several promising structural health monitoring (SHM) techniques that were recently exercised during a fatigue test of a 9 meter glass-epoxy and carbon-epoxy wind turbine blade. The SHM systems were implemented by teams from NASA Kennedy Space Center, Purdue University and Virginia Tech. A commercial off-the-shelf acoustic emission (AE) NDT system gathered blade AE data throughout the test. At a fatigue load cycle rate around 1.2 Hertz, and after more than 4,000,000 fatigue cycles, the blade was diagnostically and visibly failing at the out-board blade spar-cap termination point at 4.5 meters. For safety reasons, the test was stopped just before the blade completely failed. This paper provides an overview of the SHM and NDT system setups and some current test results.

  7. Healthcare professionals' readiness for an interprofessional orthogeriatric unit: A cross-sectional survey

    DEFF Research Database (Denmark)

    Abrahamsen, Charlotte; Nørgaard, Birgitte; Draborg, Eva

    2016-01-01

    conducted a cross-sectional survey to assess readiness for change (N=223 employees) in a hospital on the verge of implementing an interprofessional, co-managed, orthogeriatric unit. Staff members from three departments with tasks related to orthogeriatric patients were invited to answer a web...... of the orthogeriatric unit and 71.7% stated that it would “significantly promote the interdisciplinary approach” of their department. Eliciting the respondents’ readiness for change, we found that 88.5% indicated a belief that orthogeriatric care would match the hospital’s need for change, and that it would furthermore...... aspects; those voiced by the nursing staff related to work strain and the interests of their professional group whereas the physicians’ reservations concentrated on the planning of the change. The exploration of readiness for organizational change among health care professionals offers managers...

  8. Torsional Performance of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Branner, Kim; Berring, Peter; Berggreen, Christian

    2007-01-01

    The present work investigates how well different finite element modeling techniques can predict bending and torsion behavior of a wind turbine blade. Two shell models are investigated. One model has element offsets and the other has the elements at the mid-thickness surfaces of the model. The last...... two models investigated use a combination of shell and solid elements. The results from the numerical investigations are compared with measurements from testing of a section of a full-scale wind turbine blade. It is found that only the combined shell/solid models give reliable results in torsion. Both...

  9. SSME blade damper technology

    Science.gov (United States)

    Kielb, Robert E.; Griffin, Jerry H.

    1987-01-01

    Before 1975 turbine blade damper designs were based on experience and very simple mathematical models. Failure of the dampers to perform as expected showed the need to gain a better understanding of the physical mechanism of friction dampers. Over the last 10 years research on friction dampers for aeronautical propulsion systems has resulted in methods to optimize damper designs. The first-stage turbine blades on the Space Shuttle Main Engine (SSME) high-pressure oxygen pump have experienced cracking problems due to excessive vibration. A solution is to incorporate a well-designed friction dampers to attenuate blade vibration. The subject study, a cooperative effort between NASA Lewis and Carnegie-Mellon University, represents an application of recently developed friction damper technology to the SSME high-pressure oxygen turbopump. The major emphasis was the contractor's design known as the two-piece damper. Damping occurs at the frictional interface between the top half of the damper and the underside of the platforms of the adjacent blades. The lower half of the damper is an air seal to retard airflow in the volume between blade necks.

  10. The system of blade's shape measuring

    Science.gov (United States)

    Gorbachev, Alexey A.; Korotaev, Valery V.; Apehtin, Dmitri V.

    2015-02-01

    System that will allow visual and measuring control of blades is proposed. It based on triangulation method of measurement. This method implies using of elements described below: a receiving unit, source of structured light, processing and control unit, the monitor and power supply unit. Geometrical characteristics of the system are calculated. As a result we got numbers of receiving units and sources of structured light needed to monitor blade along its entire length. Theoretical error of system measurement is calculated. It depends on distance to the object, the base between receives unit and sources of structured light, resolution and physical size of image receive. Surface of blade is not flat this fact entails changing distance from object to receive unit. So the error of measurement will be different. The interval for researching was chosen from 90 to 130 mm. Error of measurement have steady upward trend from 0,08 to 0,017 mm all period between chosen distances. The physical model of control method is developed. As a result of its working picture of illuminated metal object was obtained. The program written in MatLab processes experimental picture, find lines of structure light and calculate dislocations of it. Then use this information to make a three-dimensional model of object.

  11. Experimental Investigation of Inter-Blade Vortices in a Model Francis Turbine

    Science.gov (United States)

    LIU, Demin; LIU, Xiaobing; ZHAO, Yongzhi

    2017-07-01

    The inter-blade vortex in a Francis turbine becomes one of the main hydraulic factors that are likely to cause blade erosion at deep part load operating conditions. However, the causes and the mechanism of inter-blade vortex are still under investigation according to present researches. Thus the causes of inter-blade vortex and the effect of different hydraulic parameters on the inter-blade vortex are investigated experimentally. The whole life cycle of the inter-blade vortex is observed by a high speed camera. The test results illustrate the whole life cycle of the inter-blade vortex from generation to separation and even to fading. It is observed that the inter-blade vortex becomes stronger with the decreasing of flow and head, which leads to pressure fluctuation. Meanwhile, the pressure fluctuations in the vane-less area and the draft tube section become stronger when inter-blade vortices exist in the blade channel. The turbine will be damaged if operating in the inter-blade vortex zone, so its operating range must be far away from that zone. This paper reveals the main cause of the inter-blade vortex which is the larger incidence angle between the inflow angle and the blade angle on the leading edge of the runner at deep part load operating conditions.

  12. Experimental Investigation of Inter-Blade Vortices in a Model Francis Turbine

    Science.gov (United States)

    LIU, Demin; LIU, Xiaobing; ZHAO, Yongzhi

    2017-03-01

    The inter-blade vortex in a Francis turbine becomes one of the main hydraulic factors that are likely to cause blade erosion at deep part load operating conditions. However, the causes and the mechanism of inter-blade vortex are still under investigation according to present researches. Thus the causes of inter-blade vortex and the effect of different hydraulic parameters on the inter-blade vortex are investigated experimentally. The whole life cycle of the inter-blade vortex is observed by a high speed camera. The test results illustrate the whole life cycle of the inter-blade vortex from generation to separation and even to fading. It is observed that the inter-blade vortex becomes stronger with the decreasing of flow and head, which leads to pressure fluctuation. Meanwhile, the pressure fluctuations in the vane-less area and the draft tube section become stronger when inter-blade vortices exist in the blade channel. The turbine will be damaged if operating in the inter-blade vortex zone, so its operating range must be far away from that zone. This paper reveals the main cause of the inter-blade vortex which is the larger incidence angle between the inflow angle and the blade angle on the leading edge of the runner at deep part load operating conditions.

  13. Fluid blade disablement tool

    Energy Technology Data Exchange (ETDEWEB)

    Jakaboski, Juan-Carlos [Albuquerque, NM; Hughs, Chance G [Albuquerque, NM; Todd, Steven N [Rio Rancho, NM

    2012-01-10

    A fluid blade disablement (FBD) tool that forms both a focused fluid projectile that resembles a blade, which can provide precision penetration of a barrier wall, and a broad fluid projectile that functions substantially like a hammer, which can produce general disruption of structures behind the barrier wall. Embodiments of the FBD tool comprise a container capable of holding fluid, an explosive assembly which is positioned within the container and which comprises an explosive holder and explosive, and a means for detonating. The container has a concavity on the side adjacent to the exposed surface of the explosive. The position of the concavity relative to the explosive and its construction of materials with thicknesses that facilitate inversion and/or rupture of the concavity wall enable the formation of a sharp and coherent blade of fluid advancing ahead of the detonation gases.

  14. Basic Competence of Intensive Care Unit Nurses: Cross-Sectional Survey Study

    Directory of Open Access Journals (Sweden)

    Riitta-Liisa Lakanmaa

    2015-01-01

    Full Text Available Critical care patients benefit from the attention of nursing personnel with a high competence level. The aim of the study was to describe and evaluate the self-assessed basic competence of intensive care unit nurses and related factors. A cross-sectional survey design was used. A basic competence scale (Intensive and Critical Care Nursing Competence Scale version 1, Likert scale 1–5, 1 = poor and 5 = excellent was employed among Finnish intensive care unit nurses (n=431. Intensive care unit nurses’ self-assessed basic competence was good (mean 4.19, SD 0.40. The attitude and value base of basic competence was excellent whereas experience base was the poorest compared to the knowledge base and skill base of intensive and critical care nursing. The strongest factor explaining nurses’ basic competence was their experience of autonomy in nursing care (F value 60.85, β 0.11, SE 0.01, and P≤0.0001. Clinical competence was self-rated as good. Nurses gave their highest competence self-ratings for ICU patient care according to the principles of nursing care. The ICU nurses also self-rated their professional competence as good. Collaboration was self-rated as the best competence. In basic and continuing education and professional self-development discussions it is meaningful to consider and find solutions for how to improve nurses’ experienced autonomy in nursing.

  15. Extension-twist coupling optimization in composite rotor blades

    Science.gov (United States)

    Ozbay, Serkan

    2005-07-01

    For optimal rotor performance in a tiltrotor aircraft the difference in the inflow and the rotor speeds between the hover and cruise flight modes suggests different blade twist and chord distributions. The blade twist rates in current tiltrotor applications are defined based upon a compromise between the figure of merit in hover and propeller efficiency in airplane mode. However, when each operation mode is considered separately the optimum blade distributions are found to be considerably different. Passive blade twist control, which uses the inherent variation in centrifugal forces on a rotor blade to achieve optimum blade twist distributions in each flight mode through the use of extension-twist coupled composite rotor blades, has been considered for performance improvement of tiltrotor aircraft over the last two decades. The challenge for this concept is to achieve the desired twisting deformations in the rotor blade without altering the aeroelastic characteristics of the vehicle. A concept referred to as the sliding mass concept is proposed in this work in order to increase the twist change with rotor speed for a closed-cell composite rotor blade cross-section to practical levels for performance improvement in a tiltrotor aircraft. The concept is based on load path changes for the centrifugal forces by utilizing non-structural masses readily available on a conventional blade, such as the leading edge balancing mass. A multilevel optimization technique based on the simulated annealing method is applied to improve the performance of the XV15 tiltrotor aircraft. A cross-sectional analysis tool, VABS together with a multibody dynamics code, DYMORE are integrated into the optimization process. The optimization results revealed significant improvements in the power requirement in hover while preserving cruise efficiency. It is also shown that about 21% of the improvement is provided through the sliding mass concept pointing to the additional flexibility the concept

  16. Experimental Blade Research

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Branner, Kim; Berring, Peter

    This report is a summary of the results obtained in the project: Experimental Blade Research – phase 2 (EBR2). The project was supported by the Danish Energy Authority through the 2010 Energy Technology Development and Demonstration Program (EUDP 2010-II) and has journal no. 64011-0006. The project...

  17. Database about blade faults

    DEFF Research Database (Denmark)

    Branner, Kim; Ghadirian, Amin

    This report deals with the importance of measuring the reliability of the rotor blades and describing how they can fail. The Challenge is that very little non-confidential data is available and that the quality and detail in the data is limited....

  18. Self-Expanded Clustering Algorithm Based on Density Units with Evaluation Feedback Section

    Institute of Scientific and Technical Information of China (English)

    YU Yongqian; ZHAO Xiangguo; CHEN Hengyue; WANG Bin; YU Ge; WANG Guoren

    2006-01-01

    This paper presents an effective clustering mode and a novel clustering result evaluating mode. Clustering mode has two limited integral parameters. Evaluating mode evaluates clustering results and gives each a mark. The higher mark the clustering result gains, the higher quality it has. By organizing two modes in different ways, we can build two clustering algorithms: SECDU(Self-Expanded Clustering Algorithm based on Density Units) and SECDUF(Self-Expanded Clustering Algorithm Based on Density Units with Evaluation Feedback Section). SECDU enumerates all value pairs of two parameters of clustering mode to process data set repeatedly and evaluates every clustering result by evaluating mode. Then SECDU output the clustering result that has the highest evaluating mark among all the ones. By applying "hill-climbing algorithm", SECDUF improves clustering efficiency greatly. Data sets that have different distribution features can be well adapted to both algorithms. SECDU and SECDUF can output high-quality clustering results. SECDUF tunes parameters of clustering mode automatically and no man's action involves through the whole process. In addition, SECDUF has a high clustering performance.

  19. Computation of the throat area of a turbine blade ring

    Science.gov (United States)

    Mamaev, B. I.; Murashko, V. L.

    2016-01-01

    The throat area is a geometric parameter of the blade ring necessary to profile its blades and compute the turbine capacity. As applied to the filament flow model, the area is defined by the involute of the throat solid figure onto the plane formed by the cascade throat located on one of the cylindrical sections of the blade ring and the radius. An equation is derived for computing the area of the involute, which considers the effect of the shape of the ring's tailing outlines and the fillets at the transition from the outlines to the blade feather. Comparison of the area values for several turbines computed by the derived equation and by a more complex method based on a search for the minimum distances from the tailing edge of the blade to the suction surface of the neighboring blade in the channel revealed slight differences. The fluid-dynamic 2D analysis determined the radial boundaries of the filament bands, the parameters of the cascade that lie on a filament's cylindrical surfaces, and the flow velocity normal to the throat section of the filament. The proposed approach to computation of the throat area is common for problems of both designing and analyzing the turbine operation and allows for excluding, in practice, methodological differences in determination of the flow rate and the flow angles at the outlet of the blade ring.

  20. AERODYNAMIC AND BLADING DESIGN OF MULTISTAGE AXIAL FLOW COMPRESSORS

    Science.gov (United States)

    Crouse, J. E.

    1994-01-01

    with fourth-degree polynomial functions of path distance from the maximum thickness point. Input to the aerodynamic and blading design program includes the annulus profile, the overall compressor mass flow, the pressure ratio, and the rotative speed. A number of input parameters are also used to specify and control the blade row aerodynamics and geometry. The output from the aerodynamic solution has an overall blade row and compressor performance summary followed by blade element parameters for the individual blade rows. If desired, the blade coordinates in the streamwise direction for internal flow analysis codes and the coordinates on plane sections through blades for fabrication drawings may be stored and printed. The aerodynamic and blading design program for multistage axial-flow compressors is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 series computer with a central memory requirement of approximately 470K of 8 bit bytes. This program was developed in 1981.

  1. Design and evaluation of low-cost laminated wood composite blades for intermediate size wind turbines: Blade design, fabrication concept, and cost analysis

    Science.gov (United States)

    Lieblein, S.; Gaugeon, M.; Thomas, G.; Zueck, M.

    1982-11-01

    As part of a program to reduce wind turbine costs, an evaluation was conducted of a laminated wood composite blade for the Mod-OA 200 kW wind turbine. The effort included the design and fabrication concept for the blade, together with cost and load analyses. The blade structure is composed of laminated Douglas fir veneers for the primary spar and nose sections, and honeycomb cored plywood panels for the trailing edges sections. The attachment of the wood blade to the rotor hub was through load takeoff studs bonded into the blade root. Tests were conducted on specimens of the key structural components to verify the feasibility of the concept. It is concluded that the proposed wood composite blade design and fabrication concept is suitable for Mod-OA size turbines (125-ft diameter rotor) at a cost that is very competitive with other methods of manufacture.

  2. Laser-based gluing of diamond-tipped saw blades

    Science.gov (United States)

    Hennigs, Christian; Lahdo, Rabi; Springer, André; Kaierle, Stefan; Hustedt, Michael; Brand, Helmut; Wloka, Richard; Zobel, Frank; Dültgen, Peter

    2016-03-01

    To process natural stone such as marble or granite, saw blades equipped with wear-resistant diamond grinding segments are used, typically joined to the blade by brazing. In case of damage or wear, they must be exchanged. Due to the large energy input during thermal loosening and subsequent brazing, the repair causes extended heat-affected zones with serious microstructure changes, resulting in shape distortions and disadvantageous stress distributions. Consequently, axial run-out deviations and cutting losses increase. In this work, a new near-infrared laser-based process chain is presented to overcome the deficits of conventional brazing-based repair of diamond-tipped steel saw blades. Thus, additional tensioning and straightening steps can be avoided. The process chain starts with thermal debonding of the worn grinding segments, using a continuous-wave laser to heat the segments gently and to exceed the adhesive's decomposition temperature. Afterwards, short-pulsed laser radiation removes remaining adhesive from the blade in order to achieve clean joining surfaces. The third step is roughening and activation of the joining surfaces, again using short-pulsed laser radiation. Finally, the grinding segments are glued onto the blade with a defined adhesive layer, using continuous-wave laser radiation. Here, the adhesive is heated to its curing temperature by irradiating the respective grinding segment, ensuring minimal thermal influence on the blade. For demonstration, a prototype unit was constructed to perform the different steps of the process chain on-site at the saw-blade user's facilities. This unit was used to re-equip a saw blade with a complete set of grinding segments. This saw blade was used successfully to cut different materials, amongst others granite.

  3. Flow characteristics on the blade channel vortex in the Francis turbine

    Science.gov (United States)

    Guo, P. C.; Wang, Z. N.; Luo, X. Q.; Wang, Y. L.; Zuo, J. L.

    2016-05-01

    Depending on the long-term hydraulic development of Francis turbine, the blade channel vortex phenomenon was investigated systematically from hydraulic design, experimental and numerical computation in this paper. The blade channel vortex difference between the high water head and low water head turbine was also analyzed. Meanwhile, the relationship between the blade channel vortex and the operating stability of hydraulic turbine was also investigated. The results show that the phenomenon of blade channel vortex is an intrinsic property for Francis turbine under small flow rate condition, the turning-point of the blade channel vortex inception curve appears at low unit speed region, and the variation trend of the blade channel vortex inception curve is closely related to the blade inlet edge profile. In addition to, the vortex of the high water head turbine can generally be excluded from the stable operation region, while which is more different for the one of the low water head turbine.

  4. Standard Specification for Steel Blades Used with the Photovoltaic Module Surface Cut Test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This specification specifies the recommended physical characteristics of the steel blades required for the surface cut test described in ANSI/UL 1703 (Section 24) and IEC 61730-2 (Paragraph 10.3). 1.2 ANSI/UL 1703 and IEC 61730-2 are standards for photovoltaic module safety testing. 1.3 This standard provides additional fabrication details for the surface cut test blades that are not provided in ANSI/UL 1703 or IEC 61730-2. Surface cut test blades that have out-of-tolerance corner radii or burrs are known to cause erroneous test results, either passes or failures. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  5. Graphene in turbine blades

    Science.gov (United States)

    Das, D. K.; Swain, P. K.; Sahoo, S.

    2016-07-01

    Graphene, the two-dimensional (2D) nanomaterial, draws interest of several researchers due to its many superior properties. It has extensive applications in numerous fields. A turbine is a hydraulic machine which extracts energy from a fluid and converts it into useful work. Recently, Gudukeya and Madanhire have tried to increase the efficiency of Pelton turbine. Beucher et al. have also tried the same by reducing friction between fluid and turbine blades. In this paper, we study the advantages of using graphene as a coating on Pelton turbine blades. It is found that the efficiency of turbines increases, running and maintenance cost is reduced with more power output. By the application of graphene in pipes, cavitation will be reduced, durability of pipes will increase, operation and maintenance cost of water power plants will be less.

  6. Stator Blade Laser Window Research

    Science.gov (United States)

    Lugas, Grant A.

    2004-01-01

    All turbofan engines used in modern aviation contain a series of fan blades and compressor blades which are all connected to one drive shaft. Inside the jet engine between each set of blades are stator blades, which are pitched opposite of the fan and compressor blades, the stator blades are both rotational and axial fixed in place. The project that I was assigned to involves the QAT 22 fan test rig; which is currently under final design review and very soon will be fabricated. The purpose of this research facility is to better understand the effects of stator blades. Stator blades are used to straiten the air in a turbine. The researcher's primary aim is to determine what the airflow is like at both the leading edge and the trailing edge of a stator blade. My work focused on designing the windows usable for both a compressor rig and a test fan rig. The difference between the two is the test fan application will be looking into a stator blade array rather than just looking at the rotor. My discussion will include a detailed explanation of how the PIV laser window system functions fiom start to finish. I will also discuss how the information is gathered and organized. Further more I plan to talk about the purpose of this kind of research and the advantages to using this technology to determine the airflow characteristics of blade designs. Finally I will discuss the researcher s conclusion on the relationship between aerodynamics of a blade and how noise is produced. NASA's main goal with this particular facility is find ways to quiet engine noise by reducing the amount of cavitations that occurs around the blades of a turbofan engine. Additional information is included in the original extended abstract.

  7. Stator Blade Laser Window Research

    Science.gov (United States)

    Lugas, Grant A.

    2004-01-01

    All turbofan engines used in modern aviation contain a series of fan blades and compressor blades which are all connected to one drive shaft. Inside the jet engine between each set of blades are stator blades, which are pitched opposite of the fan and compressor blades, the stator blades are both rotational and axial fixed in place. The project that I was assigned to involves the QAT 22 fan test rig; which is currently under final design review and very soon will be fabricated. The purpose of this research facility is to better understand the effects of stator blades. Stator blades are used to straiten the air in a turbine. The researcher's primary aim is to determine what the airflow is like at both the leading edge and the trailing edge of a stator blade. My work focused on designing the windows usable for both a compressor rig and a test fan rig. The difference between the two is the test fan application will be looking into a stator blade array rather than just looking at the rotor. My discussion will include a detailed explanation of how the PIV laser window system functions fiom start to finish. I will also discuss how the information is gathered and organized. Further more I plan to talk about the purpose of this kind of research and the advantages to using this technology to determine the airflow characteristics of blade designs. Finally I will discuss the researcher s conclusion on the relationship between aerodynamics of a blade and how noise is produced. NASA's main goal with this particular facility is find ways to quiet engine noise by reducing the amount of cavitations that occurs around the blades of a turbofan engine. Additional information is included in the original extended abstract.

  8. High Specification Offshore Blades: Work Package: 1B: Blades Design

    OpenAIRE

    Brown, Richard; Fletcher, Timothy; Galbraith, Roderick; York, Christopher

    2008-01-01

    This report outlines the current state of the art in offshore wind turbine blade aerodynamic design, along with the key technical limitations and possible technologies which may improve the aerodynamic design of blades and turbine rotors in the future. It is suggested that there are three principal areas in which aerodynamic improvements can be made to the design of offshore wind turbine systems: improved rotor system and blade tip design for operation at higher tip speeds, optimisation of wi...

  9. Strength Reliability Analysis of Turbine Blade Using Surrogate Models

    Directory of Open Access Journals (Sweden)

    Wei Duan

    2014-05-01

    Full Text Available There are many stochastic parameters that have an effect on the reliability of steam turbine blades performance in practical operation. In order to improve the reliability of blade design, it is necessary to take these stochastic parameters into account. In this study, a variable cross-section twisted blade is investigated and geometrical parameters, material parameters and load parameters are considered as random variables. A reliability analysis method as a combination of a Finite Element Method (FEM, a surrogate model and Monte Carlo Simulation (MCS, is applied to solve the blade reliability analysis. Based on the blade finite element parametrical model and the experimental design, two kinds of surrogate models, Polynomial Response Surface (PRS and Artificial Neural Network (ANN, are applied to construct the approximation analytical expressions between the blade responses (including maximum stress and deflection and random input variables, which act as a surrogate of finite element solver to drastically reduce the number of simulations required. Then the surrogate is used for most of the samples needed in the Monte Carlo method and the statistical parameters and cumulative distribution functions of the maximum stress and deflection are obtained by Monte Carlo simulation. Finally, the probabilistic sensitivities analysis, which combines the magnitude of the gradient and the width of the scatter range of the random input variables, is applied to evaluate how much the maximum stress and deflection of the blade are influenced by the random nature of input parameters.

  10. Effects of Dynamic Pitching on Wind Turbine Blade Performance

    Science.gov (United States)

    Naughton, Jonathan; Babbitt, Ashli; Strike, John; Hind, Michael; Magstadt, Andrew; Nikoueeyan, Pourya

    2012-11-01

    Due to turbulence in the wind and the rotation of the blade through a shear layer, wind turbine blade flows are inherently unsteady. Over the past five years, a number of wind turbine blade sections used for inboard, mid-span, and tip regions of the blade (including flatback airfoils) have been tested at a Reynolds number of 225,000. The airfoils have been tested at reduced frequencies cω / 2 U , where c is the chord length, ω is the oscillation frequency (radians/sec), and U is the air velocity ahead of the blade, relevant to commercial wind turbines. Unsteady pressure measurements and Particle Image Velocimetry (PIV) have provided information about the surface properties and surrounding flow field and their relationship. The results have shown that, depending on the reduced frequency, a lag in pressure and flow-field structures is experienced by the blade. When the blade is operating at angles above the static stall angle, delayed separation is experience as expected. The reattachment of the flow is also delayed, and, at higher reduced frequencies, the flow can remain separated throughout the entire downward pitching movement. Such dynamic data result in a better understanding of the unsteady flow physics necessary for improved designs. Support from DOE and BP is acknowledged.

  11. Wind turbine rotor blade with in-plane sweep and devices using same, and methods for making same

    Science.gov (United States)

    Wetzel, Kyle Kristopher

    2008-03-18

    A wind turbine includes a rotor having a hub and at least one blade having a torsionally rigid root, an inboard section, and an outboard section. The inboard section has a forward sweep relative to an elastic axis of the blade and the outboard section has an aft sweep.

  12. Wind turbine rotor blade with in-plane sweep and devices using the same, and methods for making the same

    Science.gov (United States)

    Wetzel, Kyle Kristopher

    2014-06-24

    A wind turbine includes a rotor having a hub and at least one blade having a torsionally rigid root, an inboard section, and an outboard section. The inboard section has a forward sweep relative to an elastic axis of the blade and the outboard section has an aft sweep.

  13. Prediction of H.A.W.T. blade stall and performance

    Energy Technology Data Exchange (ETDEWEB)

    Giannakidis, G.; Graham, J.M.R. [Imperial College, Dept. of Aeronautics, London (United Kingdom)

    1996-09-01

    A model is being developed for the prediction of Horizontal Axis Wind Turbine blade stall and performance coupled with a simple aeroelastic analysis model. For the aerodynamic calculation a two dimensional unsteady Navier-Stokes solver on a sectional basis on the blade is coupled with a three dimensional vortex lattice wake. Pressure coefficient distributions are calculated from the two dimensional viscous flow in each blade section. The aerodynamic computations are coupled with a vibrating beam model in order to incorporate flapwise deformations of the blade. (au) 17 refs.

  14. CFD-RANS analysis of the rotational effects on the boundary layer of wind turbine blades

    DEFF Research Database (Denmark)

    Carcangiu, Carlo Enrico; Sørensen, Jens Nørkær; Cambuli, Francesco

    2007-01-01

    The flow field past the rotating blade of a horizontal axis wind turbine has been modeled with a full 3-D steady-RANS approach. Flow computations have been performed using the commercial finite-volume solver Fluent. A number of blade sections from the 3-D rotating geometry were chosen and the cor......The flow field past the rotating blade of a horizontal axis wind turbine has been modeled with a full 3-D steady-RANS approach. Flow computations have been performed using the commercial finite-volume solver Fluent. A number of blade sections from the 3-D rotating geometry were chosen...

  15. 77 FR 43573 - Request for Applicants for Appointment to the United States Section of the United States-Turkey...

    Science.gov (United States)

    2012-07-25

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE... otherwise legally authorized to work in the United States, and be able to travel to Turkey and locations in.... In addition, the applicant may not be a registered foreign agent under the Foreign...

  16. Evaluation of blood reservation and use for caesarean sections in a tertiary maternity unit in south western Nigeria

    Directory of Open Access Journals (Sweden)

    Oshodi Yussuf A

    2010-09-01

    Full Text Available Abstract Background Haemorrhage from obstetric causes is the most common cause of maternal mortality in the developing world. Prevention of mortality from haemorrhage will necessarily involve prompt blood transfusions among other life saving measures. There are however limited stocks of fresh or stored blood in many health care facilities in Sub Saharan Africa. Caesarean section has been identified as a common indication for blood transfusion in obstetrics practice and its performance is often delayed by non availability of blood in our centre. An evaluation of blood reservation and use at caesarean sections in a tertiary maternity unit in Lagos, south western Nigeria should therefore assist in formulating the most rational blood transfusion policies. Methods Case records of 327 patients who had elective and emergency caesarian sections at the Lagos State University Teaching Hospital between 1st October and 31st December 2007 were reviewed. Data pertaining to age, parity, booking status, type and indication for Caesarean section, pre- and post-operative packed cell volume, blood loss at surgery, units of blood reserved in the blood bank, unit(s of blood transfused and duration of hospital stay was extracted and the data analysed. Results There were 1056 deliveries out of which 327 (31% were by Caesarean section. During the study period, a total of 654 units of blood were reserved in the blood bank and subsequently made available in theatre. Out of this number, only 89 (13.6% were transfused to 41 patients. Amongst those transfused, twenty-six (54% were booked and 31 (75.6% had primary caesarian section. About 81% of those transfused had emergency caesarean section. The most common indication for surgery among those transfused were placenta praevia (9 patients with 21 units of blood and cephalo-pelvic disproportion (8 patients with 13 units. Conclusion Even though a large number of units of blood was reserved and made available in the theatre at

  17. A Reinforced Blade for a Wind Turbine

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a reinforced blade for a wind turbine having elongated reinforcing members in the blade extending substantially in the plane of the profile chord in order to strengthen the blade against edgewise and flapwise forces....

  18. SHM of wind turbine blades using piezoelectric active-sensors

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gyuhae [Los Alamos National Laboratory; Taylor, Stuart G [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Farrar, Charles R [Los Alamos National Laboratory

    2010-01-01

    This paper presents a variety of structural health monitoring (SHM) techniques, based on the use of piezoelectric active-sensors, used to determine the structural integrity of wind turbine blades. Specifically, Lamb wave propagations, frequency response functions, and time series based methods are utilized to estimate the condition of wind turbine blades. For experiments, a 1m section of a 9m CX100 blade is used. Overall, these three methods yielded a sufficient damage detection capability to warrant further investigation into field deployment. A full-scale fatigue test of a CX-100 wind turbine blade is also conducted. This paper summarizes considerations needed to design such SHM systems, experimental procedures and results, and practical implementation issues that can be used as guidelines for future investigations.

  19. Determination of the angle of attack on rotor blades

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Hansen, Martin Otto Laver; Sørensen, Jens Nørkær

    2009-01-01

    Two simple methods for determining the angle of attack (AOA) on a section of a rotor blade are proposed. Both techniques consist of employing the Biot-Savart integral to determine the influence of the bound vorticity on the velocity field. In the first technique, the force distribution along...... the blade and the velocity at a monitor point in the vicinity of the blade are assumed to be known from experiments or CFD computations. The AOA is determined by subtracting the velocity induced by the bound circulation, determined from the loading, from the velocity at the monitor point. In the second...... to be located closer to the blade, and thus to determine the AOA with higher accuracy. Data from CFD computations for flows past the Tellus 95 kW wind turbine at different wind speeds are used to test both techniques. Comparisons show that the proposed methods are in good agreement with existing techniques...

  20. Secular trends in caesarean section rates over 20 years in a regional obstetric unit in Hong Kong.

    Science.gov (United States)

    Chung, W H; Kong, C W; To, W Wk

    2017-08-01

    Although caesarean section rates have been increasing over the years in both public and private sectors in Hong Kong, there has been a paucity of formal surveys on local trends in such rates. This study aimed to examine the trends in caesarean section rates over a 20-year period at a public regional obstetric unit in Hong Kong using the Robson's Ten-group Classification System. All deliveries in a single obstetric unit during a 20-year period (1995-2014) were classified into 10 subgroups according to the Robson's classification. The annual caesarean section rate for each subgroup was calculated and then stratified into 5-year intervals to analyse any significant trends. The caesarean section rates in a total of 86 262 births with complete data were analysed. The overall caesarean section rate increased modestly from 15.4% to 24.6% during the study period. There was an obvious increasing trend for caesarean section in those with previous caesarean section (Robson's category 5), breech presentation at delivery (category 6 and 7), multiple pregnancy (category 8), and preterm labour (category 10). A gradual fall in caesarean section rate from 14.4% to 10.8% was seen in primiparous women with term spontaneous labour (category 1). Statistically significant differences (Psection rate may be associated with clinical management policies that allow women with relative risk factors (such as breech, previous caesarean section, or multiple pregnancy) to opt for caesarean section. This rise was counterbalanced by a decrease in primary caesarean section rate in primiparous women with spontaneous labour. The trend for caesarean section was more in line with patient expectations rather than evidence-based practice.

  1. Aeroelastic analysis for helicopter rotors with blade appended pendulum vibration absorbers. Mathematical derivations and program user's manual

    Science.gov (United States)

    Bielawa, R. L.

    1982-01-01

    Mathematical development is presented for the expanded capabilities of the United Technologies Research Center (UTRC) G400 Rotor Aeroelastic Analysis. This expanded analysis, G400PA, simulates the dynamics of teetered rotors, blade pendulum vibration absorbers and the higher harmonic excitations resulting from prescribed vibratory hub motions and higher harmonic blade pitch control. Formulations are also presented for calculating the rotor impedance matrix appropriate to these higher harmonic blade excitations. This impedance matrix and the associated vibratory hub loads are intended as the rotor blade characteristics elements for use in the Simplified Coupled Rotor/Fuselage Vibration Analysis (SIMVIB). Sections are included presenting updates to the development of the original G400 theory, and material appropriate to the user of the G400PA computer program. This material includes: (1) a general descriptionof the tructuring of the G400PA FORTRAN coding, (2) a detaild description of the required input data and other useful information for successfully running the program, and (3) a detailed description of the output results.

  2. A Reinforced Blade for a Wind Turbine

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a reinforced blade for a wind turbine having elongated reinforcing members in the blade extending substantially in the plane of the profile chord in order to strengthen the blade against edgewise and flapwise forces.......The present invention relates to a reinforced blade for a wind turbine having elongated reinforcing members in the blade extending substantially in the plane of the profile chord in order to strengthen the blade against edgewise and flapwise forces....

  3. KNOW-BLADE task-3.3 report: Rotor blade computations with 3D vortex generators

    DEFF Research Database (Denmark)

    Johansen, J.; Sørensen, Niels N.; Reck, M.

    2005-01-01

    . They are: 1) A non-rotating airfoil section with VGs. 2) A rotating airfoil section with VGs. 3) A non-rotating wind turbine blade with VGs. The airfoil section was the FFA-W3-241 airfoil, which has beenmeasured in the VELUX wind tunnel with and without VGs placed at different chord wise positions. Three...... vortex generators in 3D, which eventually generates vortices and mixes the boundary layer.A large effort has been on generating the numerical meshes since this is a relatively complex configuration and a large variation of length and time scales is present. Even though the quantitative agreement...... with measurements is not acceptable the effortspend in the present project indicate that it is possible to investigate the effect of vortex generators on wind turbine blades using 3D Navier-Stokes solvers. Much further work within independence of mesh resolution and time step as well as turbulencemodelling has...

  4. Automated design of controlled-diffusion blades

    Science.gov (United States)

    Sanz, J. M.

    1988-01-01

    A numerical automation procedure has been developed to be used in conjunction with an inverse hodograph method for the design of controlled diffusion blades. With this procedure a cascade of airfoils with a prescribed solidity, inlet Mach number, inlet air flow angle, and air flow turning can be produced automatically. The trailing edge thickness of the airfoil, an important quantity in inverse methods, is also prescribed. The automation procedure consists of a multidimensional Newton iteration in which the objective design conditions are achieved by acting on the hodograph input parameters of the underlying inverse code. The method, although more general in scope, is applied in this paper to the design of axial flow compressor blade sections, and a wide range of examples is presented.

  5. Automated design of controlled diffusion blades

    Science.gov (United States)

    Sanz, Jose M.

    1989-01-01

    A numerical automation procedure was developed to be used in conjunction with an inverse hodograph method for the design of controlled diffusion blades. With this procedure a cascade of airfoils with a prescribed solidity, inlet Mach No., inlet air flow angle and air flow turning can be produced automatically. The trailing edge thickness of the airfoil, an important quantity in inverse methods, is also prescribed. The automation procedure consists of a multi-dimensional Newton iteration in which the objective design conditions are achieved by acting on the hodograph input parameters of the underlying inverse code. The method, although more general in scope, is applied to the design of axial flow turbomachinery blade sections, both compressors and turbines. A collaborative effort with U.S. Engine Companies to identify designs of interest to the industry will be described.

  6. Vibration Characteristics Determined for Stainless Steel Sandwich Panels With a Metal Foam Core for Lightweight Fan Blade Design

    Science.gov (United States)

    Ghosn, Louis J.; Min, James B.; Raj, Sai V.; Lerch, Bradley A.; Holland, Frederic A., Jr.

    2004-01-01

    The goal of this project at the NASA Glenn Research Center is to provide fan materials that are safer, weigh less, and cost less than the currently used titanium alloy or polymer matrix composite fans. The proposed material system is a sandwich fan construction made up of thin solid face sheets and a lightweight metal foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by the foam layer. The resulting structure has a high stiffness and lighter weight in comparison to the solid facesheet material alone. The face sheets carry the applied in-plane and bending loads (ref. 1). The metal foam core must resist the transverse shear and transverse normal loads, as well as keep the facings supported and working as a single unit. Metal foams have ranges of mechanical properties, such as light weight, impact resistance, and vibration suppression (ref. 2), which makes them more suitable for use in lightweight fan structures. Metal foams have been available for decades (refs. 3 and 4), but the difficulties in the original processes and high costs have prevented their widespread use. However, advances in production techniques and cost reduction have created a new interest in this class of materials (ref. 5). The material chosen for the face sheet and the metal foam for this study was the aerospace-grade stainless steel 17-4PH. This steel was chosen because of its attractive mechanical properties and the ease with which it can be made through the powder metallurgy process (ref. 6). The advantages of a metal foam core, in comparison to a typical honeycomb core, are material isotropy and the ease of forming complex geometries, such as fan blades. A section of a 17-4PH sandwich structure is shown in the following photograph. Part of process of designing any blade is to determine the natural frequencies of the particular blade shape. A designer needs to predict the resonance frequencies of a new blade design to properly identify a useful

  7. Improved Attachment Design for Ceramic Turbine Blades Via Hybrid Concepts Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal presents a hybrid metal-CMC turbine blade. A SiC/SiC CMC airfoil section will be bonded to a single crystal superalloy root section in order to...

  8. Integrated circuit cooled turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ching-Pang; Jiang, Nan; Um, Jae Y.; Holloman, Harry; Koester, Steven

    2017-08-29

    A turbine rotor blade includes at least two integrated cooling circuits that are formed within the blade that include a leading edge circuit having a first cavity and a second cavity and a trailing edge circuit that includes at least a third cavity located aft of the second cavity. The trailing edge circuit flows aft with at least two substantially 180-degree turns at the tip end and the root end of the blade providing at least a penultimate cavity and a last cavity. The last cavity is located along a trailing edge of the blade. A tip axial cooling channel connects to the first cavity of the leading edge circuit and the penultimate cavity of the trailing edge circuit. At least one crossover hole connects the penultimate cavity to the last cavity substantially near the tip end of the blade.

  9. Wind Turbine Blade Design System - Aerodynamic and Structural Analysis

    Science.gov (United States)

    Dey, Soumitr

    2011-12-01

    The ever increasing need for energy and the depletion of non-renewable energy resources has led to more advancement in the "Green Energy" field, including wind energy. An improvement in performance of a Wind Turbine will enhance its economic viability, which can be achieved by better aerodynamic designs. In the present study, a design system that has been under development for gas turbine turbomachinery has been modified for designing wind turbine blades. This is a very different approach for wind turbine blade design, but will allow it to benefit from the features inherent in the geometry flexibility and broad design space of the presented system. It starts with key overall design parameters and a low-fidelity model that is used to create the initial geometry parameters. The low-fidelity system includes the axisymmetric solver with loss models, T-Axi (Turbomachinery-AXIsymmetric), MISES blade-to-blade solver and 2D wing analysis code XFLR5. The geometry parameters are used to define sections along the span of the blade and connected to the CAD model of the wind turbine blade through CAPRI (Computational Analysis PRogramming Interface), a CAD neutral API that facilitates the use of parametric geometry definition with CAD. Either the sections or the CAD geometry is then available for CFD and Finite Element Analysis. The GE 1.5sle MW wind turbine and NERL NASA Phase VI wind turbine have been used as test cases. Details of the design system application are described, and the resulting wind turbine geometry and conditions are compared to the published results of the GE and NREL wind turbines. A 2D wing analysis code XFLR5, is used for to compare results from 2D analysis to blade-to-blade analysis and the 3D CFD analysis. This kind of comparison concludes that, from hub to 25% of the span blade to blade effects or the cascade effect has to be considered, from 25% to 75%, the blade acts as a 2d wing and from 75% to the tip 3D and tip effects have to be taken into account

  10. Indiana Studies: Hoosier History, Government, and People. Unit III: From Sectional Division to Political Unity.

    Science.gov (United States)

    Barger, Harry D.; And Others

    Unit 3 of a six-unit series on Indiana state history designed to be taught in Indiana secondary schools tells the story of Indiana from 1829 to 1908. Chapter 1 discusses national issues in an Indiana context. The effects of social movements such as Abolition, the underground railroad, and the Fugitive Slave Law on Indiana politics are examined.…

  11. The Influence of Eroded Blades on Wind Turbine Performance Using Numerical Simulations

    Directory of Open Access Journals (Sweden)

    Matthias Schramm

    2017-09-01

    Full Text Available During their operation, wind turbine blades are eroded due to rain and hail, or they are contaminated with insects. Since the relative inflow velocity is higher at the outer than at the inner part of the blades, erosion occurs mostly at the outer blade region. In order to prevent strong erosion, it is possible to install a leading edge protection, which can be applied to the blades after the initial installation, but changes the shape of the initial airfoil sections. It is unclear how this modification influences the aerodynamic performance of the turbine. Hence, it is investigated in this work. The NREL 5 MW turbine is simulated with clean and eroded blades, which are compared to coated blades equipped with leading edge protection. Aerodynamic polars are generated by means of Computational Fluid Dynamics, and load calculations are conducted using the blade element momentum theory. The analysis in this work shows that, compared to clean rotor blades, the worse aerodynamic behaviour of strongly eroded blades can lead to power losses of 9 % . In contrast, coated blades only have a small impact on the turbine power of less than 1 % .

  12. Methodology for testing subcomponents; background and motivation for subcomponent testing of wind turbine rotor blades

    DEFF Research Database (Denmark)

    Antoniou, Alexandros; Branner, Kim; Lekou, D.J.

    2016-01-01

    that cannot be verified through the currently followed testing procedures and recommend ways to overcome these limitations. The work is performed within Work-Package WP7.1 entitled “Improved and validated wind turbine structural reliability - Efficient blade structure” of the IRPWIND programme. The numerical...... for blade design, highlighting the current state of the art. The review of the full-scale blade testing procedure is performed under Section 3, followed by the discussion on the issues of verification of design and manufacture performed through testing. Finally, methodologies for testing blade subcomponents...

  13. Multipath Suppression with an Absorber for UWB Wind Turbine Blade Deflection Sensing Systems

    DEFF Research Database (Denmark)

    Zhang, Shuai; Franek, Ondrej; Eggers, Patrick Claus F.

    2017-01-01

    . Applying the tip antenna inside a blade is highly preferred in practice, but it leads to strong multipath. The multipath may cause interference and cancellation to the direct pulse, and affect the accuracy of tip-root distance estimations. In this paper, a method of utilizing an absorber inside the blade...... to suppress the multipath is proposed for the in-blade tip antenna. The physical mechanism of the proposed idea is described with a simplified multipath model. Simulations are performed with a 2.5 m long blade tip section to investigate the tendencies of how the absorber affects pulse waveforms. More accurate...

  14. A morphing trailing edge flap system for wind turbine blades

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Barlas, Athanasios; Løgstrup Andersen, Tom

    2015-01-01

    and glued together with a load carrying part with a connector part that allows an easy attachment on the blade section. After tests in the laboratory the flap was mounted on a 2m long blade section mounted on a newly developed test rig. A 10m long boom with the blade section was installed on a 100kW turbine...... hub where the original blades were taken down. It means that the flap system was tested under realistic rotating conditions with real atmospheric turbulent inflow and with a g loading up to 10g which represents the conditions on the outer part of a MW turbine blade. The measured performance......The development of a morphing trailing edge system for wind turbines, also called a flap system, is presented. The functionality is simple as the flap deflection is controlled by pressurized air or a fluid in a number of voids in the flap made of an elastic material. It is thus a robust system...

  15. Structural and mechanism design of an active trailing-edge flap blade

    DEFF Research Database (Denmark)

    Lee, Jae Hwan; Natarajan, Balakumaran; Eun, Won Jong

    2013-01-01

    of excessive hub vibratory loads and noise. The active control device manipulates the blade pitch angle with arbitrary higher harmonic frequencies individually. In this paper, an active trailing-edge flap blade, which is one of the active control methods, is developed to reduce vibratory loads and noise...... of the rotor through modification of unsteady aerodynamic loads. Piezoelectric actuators installed inside the blade manipulate the motion of the trailing edge flap. The proposed blade rotates at higher speed and additional structures are included to support the actuators and the flap. This improves the design......, as the blade is able to withstand increased centrifugal force. The cross-section of the active blade is designed first. A stress/strain recovery analysis is then conducted to verify its structural integrity. A one-dimensional beam analysis is also carried out to assist with the construction of the fan diagram...

  16. [Blade auricular septostomy].

    Science.gov (United States)

    Ledesma Velasco, M; Nuñez Garduño, D; Salgado Escobar, J L; Munayer Calderón, J; Rodríguez Hernández, L; Rangel Abundis, A

    1987-01-01

    We describe the first case of BAS in our country in a three months old child with transposition of the great arteries, restrictive atrial septal defect (RASD) and intact interventricular septum. When he was 15 days old, we performed a balloon atrial septostomy. He had temporal improvement and six weeks later his cyanosis increased, and a new catheterization showed systemic arterial oxygen saturation of 30%, RASD and an interatrial pressure gradient of 2.1 mmHg (left atrium LA: 3.9 and right atrium RA: 1.8). We decided to perform a new septostomy with Park's blade atrial septostomy catheter. After the procedure the interatrial pressure gradient decreased to 0.2 mmHg (RA: 4.3 and LA: 4.5), the angiography shunt and atrial pressures increased. Five months later the child is alive and the systemic arterial oxygen saturation is 51.3%. The technique, advantages and complications are described.

  17. Turbine Blade Alloy

    Science.gov (United States)

    MacKay, Rebecca

    2001-01-01

    The High Speed Research Airfoil Alloy Program developed a fourth-generation alloy with up to an +85 F increase in creep rupture capability over current production airfoil alloys. Since improved strength is typically obtained when the limits of microstructural stability are exceeded slightly, it is not surprising that this alloy has a tendency to exhibit microstructural instabilities after high temperature exposures. This presentation will discuss recent results obtained on coated fourth-generation alloys for subsonic turbine blade applications under the NASA Ultra-Efficient Engine Technology (UEET) Program. Progress made in reducing microstructural instabilities in these alloys will be presented. In addition, plans will be presented for advanced alloy development and for computational modeling, which will aid future alloy development efforts.

  18. Microwaves Sensor for Wind Turbine Blade Inspection

    Science.gov (United States)

    Li, Zhen; Haigh, Arthur; Soutis, Constantinos; Gibson, Andrew; Sloan, Robin

    2017-04-01

    The structural integrity of wind turbine blades can be adversely affected by their structural dynamics, temperature extremes, lightning strikes, ultraviolet radiation from sunlight and airborne particulate matter such as hailstones and sand. If subsurface delamination occurs and is undetected then this can lead to fibre breakage and catastrophic failures in composite blades. In this paper we introduce a microwave scanning technique that detects such delamination in practical blade assemblies. Using an open-ended waveguide sensor, the electromagnetic signal reflected from the composite is found to have a phase profile that can detect changes in the composite cross section. Glass fibre T-joints are scanned and the results used to detect thickness variations (e.g., the presence of the web) and delamination. Results are compared across the 18-20 GHz frequency band. The dielectric permittivity of the composite system is measured and is used to estimate the stand-off distance and operating frequency of the sensor. This is critical to the system's ability to detect damage. When the sensor is close to the surface of the structure (standoff distance ≈ 5 mm), delamination down to 0.2 mm in width could be detected.

  19. The performance & flow visualization studies of three-dimensional (3-D) wind turbine blade models

    Science.gov (United States)

    Sutrisno, Prajitno, Purnomo, W., Setyawan B.

    2016-06-01

    Recently, studies on the design of 3-D wind turbine blades have a less attention even though 3-D blade products are widely sold. In contrary, advanced studies in 3-D helicopter blade tip have been studied rigorously. Studies in wind turbine blade modeling are mostly assumed that blade spanwise sections behave as independent two-dimensional airfoils, implying that there is no exchange of momentum in the spanwise direction. Moreover, flow visualization experiments are infrequently conducted. Therefore, a modeling study of wind turbine blade with visualization experiment is needed to be improved to obtain a better understanding. The purpose of this study is to investigate the performance of 3-D wind turbine blade models with backward-forward swept and verify the flow patterns using flow visualization. In this research, the blade models are constructed based on the twist and chord distributions following Schmitz's formula. Forward and backward swept are added to the rotating blades. Based on this, the additional swept would enhance or diminish outward flow disturbance or stall development propagation on the spanwise blade surfaces to give better blade design. Some combinations, i. e., b lades with backward swept, provide a better 3-D favorable rotational force of the rotor system. The performance of the 3-D wind turbine system model is measured by a torque meter, employing Prony's braking system. Furthermore, the 3-D flow patterns around the rotating blade models are investigated by applying "tuft-visualization technique", to study the appearance of laminar, separated, and boundary layer flow patterns surrounding the 3-dimentional blade system.

  20. Novel Compressor Blade Design Study

    Science.gov (United States)

    Srinivas, Abhay

    Jet engine efficiency goals are driving compressors to higher pressure ratios and engines to higher bypass ratios, each one driving to smaller cores. This is leading to larger tip gaps relative to the blade height. These larger relative tip clearances would negate some of the cycle improvements, and ways to mitigate this effect must be found. A novel split tip blade geometry has been created which helps improve the efficiency at large clearances while also improving operating range. Two identical blades are leaned in opposite directions starting at 85% span. They are cut at mid chord and the 2 halves then merged together so a split tip is created. The result is similar to the alula feathers on a soaring bird. The concept is that the split tip will energize the tip flow and increase range. For higher relative tip clearance, this will also improve efficiency. The 6th rotor of a highly loaded 10 stage machine was chosen as the baseline for this study. Three dimensional CFD simulations were performed using CD Adapco's Star-CCM+ at 5 clearances for the baseline and split tip geometry. The choking flow and stall margin of the split tip blade was higher than that of the baseline blade for all tip clearances. The pressure ratio of the novel blade was higher than that of the baseline blade near choke, but closer to stall it decreased. The sensitivity of peak efficiency to clearance was improved. At tight clearances of 0.62% of blade height, the maximum efficiency of the new design was less than the baseline blade, but as the tip clearance was increased above 2.5%, the maximum efficiency increased. Structural analysis was also performed to ascertain the feasibility of the design.

  1. The Effect of Mounting Vortex Generators on the DTU 10MW Reference Wind Turbine Blade

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac; Bak, Christian

    2014-01-01

    The aim of the current work is to analyze possible advantages of mounting Vortex Generators (VG's) on a wind turbine blade. Specifically, the project aims at investigating at which radial sections of the DTU 10 MW Reference Wind Turbine blade it is most beneficial to mount the VG's in order...

  2. Rotor blade assembly having internal loading features

    Energy Technology Data Exchange (ETDEWEB)

    Soloway, Daniel David

    2017-05-16

    Rotor blade assemblies and wind turbines are provided. A rotor blade assembly includes a rotor blade having exterior surfaces defining a pressure side, a suction side, a leading edge and a trailing edge each extending between a tip and a root, the rotor blade defining a span and a chord, the exterior surfaces defining an interior of the rotor blade. The rotor blade assembly further includes a loading assembly, the loading assembly including a weight disposed within the interior and movable generally along the span of the rotor blade, the weight connected to a rotor blade component such that movement of the weight towards the tip causes application of a force to the rotor blade component by the weight. Centrifugal force due to rotation of the rotor blade biases the weight towards the tip.

  3. Blood pressure control in hypertensive patients within Family Health Program versus at Primary Healthcare Units: analytical cross-sectional study.

    Science.gov (United States)

    Martins, Telma Lima; Atallah, Alvaro Nagib; Silva, Edina Mariko Koga da

    2012-01-01

    Hypertension is a public health problem due to its high prevalence and long-term cardiovascular complications. In Brazil in 2005, cardiovascular diseases were responsible for 28% of all deaths. Efforts are being made within primary care to achieve adequate hypertension control. The Family Health Program (FHP) has the aims of promoting quality of life and intervening in factors that put this at risk. The objective of this study was to evaluate the rate of blood pressure control among patients followed up at FHP units compared with those at primary healthcare units (PHUs). Analytical cross-sectional study in the municipality of Petrópolis, Rio de Janeiro, from January to December 2005. Five hundred patients with a diagnosis of hypertension were included: 250 were being followed up at two FHP units and 250 at two PHUs. The diagnosis of hypertension was based on the Fourth Brazilian Hypertension Consensus, and the patients needed to have been under follow-up at the units for at least 12 months. Patients' blood pressure was considered to be under control if it was less than 140/90 mmHg at the last consultation. Blood pressure was under control in 29.2% (n = 73) at FHP units and 39.23% (n = 98) at PHUs (odds ratio = 0.64; confidence interval = 0.44-0.93; P = 0.024). Blood pressure control was better among patients followed up at PHUs than among those followed up at FHP units.

  4. Bed Utilisation in an Irish Regional Paediatric Unit A Cross-Sectional Study Using the Paediatric Appropriateness Evaluation Protocol (PAEP)

    LENUS (Irish Health Repository)

    Ó hAiseadha, Coilín

    2016-05-01

    Increasing demand for limited healthcare resources raises questions about appropriate use of inpatient beds. In the first paediatric bed utilisation study at a regional university centre in Ireland, we conducted a cross-sectional study to audit the utilisation of inpatient beds at the Regional Paediatric Unit (RPU) in University Hospital Limerick (UHL), Limerick, Ireland and also examined hospital activity data, to make recommendations for optimal use of inpatient resources.

  5. Coping behavior and risk and resilience stress factors in French regional emergency medicine unit workers: a cross-sectional survey

    OpenAIRE

    AI, Lala; LM, Sturzu; JP, Picard; F, Druot; F, Grama; G, Bobirnac

    2016-01-01

    The Emergency Department (ED) has the highest workload in a hospital, offering care to patients in their most acute state of illness, as well as comforting their families and tending to stressful situations of the physical and psychological areal. Method. A cross-sectional survey of 366 Emergency Unit staff members including medical doctors, medical residents, medical nurses and ward aids, was undergone. Study participants came from four periphery hospitals in the Moselle Department of Easter...

  6. Urban sprawl, obesity, and cancer mortality in the United States: cross-sectional analysis and methodological challenges

    OpenAIRE

    Berrigan, David; Tatalovich, Zaria; Pickle, Linda W; Ewing, Reid; Ballard-Barbash, Rachel

    2014-01-01

    Background Urban sprawl has the potential to influence cancer mortality via direct and indirect effects on obesity, access to health services, physical activity, transportation choices and other correlates of sprawl and urbanization. Methods This paper presents a cross-sectional analysis of associations between urban sprawl and cancer mortality in urban and suburban counties of the United States. This ecological analysis was designed to examine whether urban sprawl is associated with total an...

  7. Application of Circulation Controlled Blades for Vertical Axis Wind Turbines

    Directory of Open Access Journals (Sweden)

    Velissarios Kourkoulis

    2013-07-01

    Full Text Available The blades of a vertical axis wind turbine (VAWT rotor see an inconsistent angle of attack through its rotation. Consequently, VAWT blades generally use symmetrical aerofoils with a lower lift-to-drag ratio than cambered aerofoils tailored to maximise horizontal axis wind turbine rotor performance. This paper considers the feasibility of circulation controlled (CC VAWT blades, using a tangential air jet to provide lift and therefore power augmentation. However CC blade sections require a higher trailing-edge thickness than conventional sections giving rise to additional base drag. The choice of design parameters is a compromise between lift augmentation, additional base drag as well as the power required to pump the air jet. Although CC technology has been investigated for many years, particularly for aerospace applications, few researchers have considered VAWT applications. This paper considers the feasibility of the technology, using Computational Fluid Dynamics to evaluate a baseline CC aerofoil with different trailing-edge ellipse shapes. Lift and drag increments due to CC are considered within a momentum based turbine model to determine net power production. The study found that for modest momentum coefficients significant net power augmentation can be achieved with a relatively simple aerofoil geometry if blowing is controlled through the blades rotation.

  8. Turbine Blade Image Processing System

    Science.gov (United States)

    Page, Neal S.; Snyder, Wesley E.; Rajala, Sarah A.

    1983-10-01

    A vision system has been developed at North Carolina State University to identify the orientation and three dimensional location of steam turbine blades that are stacked in an industrial A-frame cart. The system uses a controlled light source for structured illumination and a single camera to extract the information required by the image processing software to calculate the position and orientation of a turbine blade in real time.

  9. Blade tip timing (BTT) uncertainties

    Science.gov (United States)

    Russhard, Pete

    2016-06-01

    Blade Tip Timing (BTT) is an alternative technique for characterising blade vibration in which non-contact timing probes (e.g. capacitance or optical probes), typically mounted on the engine casing (figure 1), and are used to measure the time at which a blade passes each probe. This time is compared with the time at which the blade would have passed the probe if it had been undergoing no vibration. For a number of years the aerospace industry has been sponsoring research into Blade Tip Timing technologies that have been developed as tools to obtain rotor blade tip deflections. These have been successful in demonstrating the potential of the technology, but rarely produced quantitative data, along with a demonstration of a traceable value for measurement uncertainty. BTT technologies have been developed under a cloak of secrecy by the gas turbine OEM's due to the competitive advantages it offered if it could be shown to work. BTT measurements are sensitive to many variables and there is a need to quantify the measurement uncertainty of the complete technology and to define a set of guidelines as to how BTT should be applied to different vehicles. The data shown in figure 2 was developed from US government sponsored program that bought together four different tip timing system and a gas turbine engine test. Comparisons showed that they were just capable of obtaining measurement within a +/-25% uncertainty band when compared to strain gauges even when using the same input data sets.

  10. Advanced thin dicing blade for sapphire substrate

    Directory of Open Access Journals (Sweden)

    Koji Matsumaru, Atsushi Takata and Kozo Ishizaki

    2005-01-01

    Full Text Available Advanced thin dicing blades for cutting sapphire were fabricated and evaluated for cutting performance with respect to dicing blade wear and meandering of cutting lines. Three kinds of different commercial blades were used to compare the cutting performance. These blades had the same thickness and the same diamond grain size. The matrix material of one dicing blade was nickel–phosphorus alloy and two other were a vitric material. Newly developed dicing blades consisted of a vitric material with pore. A dicing machine was used for cutting sapphire. Turning velocity, cutting depth and feeding rate were 20,000 min−1, 200 μm and 1 mm s−1, respectivity. Cutting directions were 110 and 010. All blades could cut 1000 mm and more in the 110 direction. On the other hand, commercial dicing blades generated meandering lines and were broken only by 50 mm of cutting length in 010 direction. Fabricated blade can cut 1000 mm and more in 010 direction. The wear of fabricated dicing blade was the largest in the dicing blades. Although cutting performance of commercial dicing blades depended on the sapphire orientation, that of fabricated blade was independent of the sapphire orientation. It has been confirmed that the fabricated dicing blade was kept a cutting ability by flash diamonds on the dicing blade surface, which were created by wear of blade during cutting sapphire. Low cutting ability of commercial blades increased cutting force between with increase of cutting length. The increased cutting force produced to bend a blade and cutting lines, and finally a fracture of blade.

  11. Structural analysis of composite wind turbine blades nonlinear mechanics and finite element models with material damping

    CERN Document Server

    Chortis, Dimitris I

    2013-01-01

    This book concerns the development of novel finite elements for the structural analysis of composite beams and blades. The introduction of material damping is also an important aspect of composite structures and it is presented here in terms of their static and dynamic behavior. The book thoroughly presents a new shear beam finite element, which entails new blade section mechanics, capable of predicting structural blade coupling due to composite coupling and/or internal section geometry. Theoretical background is further expanded towards the inclusion of nonlinear structural blade models and damping mechanics for composite structures. The models effectively include geometrically nonlinear terms due to large displacements and rotations, improve the modeling accuracy of very large flexible blades, and enable the modeling of rotational stiffening and buckling, as well as, nonlinear structural coupling. Validation simulations on specimen level study the geometric nonlinearities effect on the modal frequencies and...

  12. Dynamic investigation of twist-bend coupling in a wind turbine blade

    DEFF Research Database (Denmark)

    Luczak, M.; Manzato, S.; Peeters, B.;

    2011-01-01

    This paper presents some results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study in static and dynamic domains on the bend-twist coupling in the full scale section of a wind turbine blade structure. The main goal of the conducted...... research is to confirm experimentally the numerical prediction of modification of the dynamic and static properties of a wind turbine blade. The bend-twist coupling was implemented by adding angled UD (UniDirectional) layers on the suction and pressure side of the blade. Static and dynamic tests were...... performed on a section of the full scale wind turbine blade provided by VestasWind Systems A/S. The results are presented and compared with the measurements of the original and modified blade. Comparison analysis confirmed that UD layers introduce measurable bend-twist couplings, which was not present...

  13. Termovision and electricity capacitance measurements as a evaluation of a helicopter rotor’s blades delamination

    Directory of Open Access Journals (Sweden)

    Gębura Andrzej

    2015-12-01

    Full Text Available The article presents essential elements reached during investigations of heat section of rotor blades which have been done in AFIT. The investigations were related to a valuation of helicopter’s rotor blades delamination. They used a method of thermal field measurement as well as a electricity capacitance between an airframe and a heat element of the installation. A suggestion of such measurements appeared during the disassembly of rotor blade heat sections when some local unglue of heat element’s tape from the structure of blade’s heating pack has seen. Spots nearby separation of adhesive are a potential area of a local temperature increase, both the electric heating element and the mechanical structure of the blade. This is especially dangerous for composite structures. Overheated composite structures characterized by reduced flexibility and becomes prone to cracking. Therefore, the possibility of non-invasive monitoring adhesive spots, without removing the blades would be particularly useful.

  14. Dynamic investigation of twist-bend coupling in a wind turbine blade

    DEFF Research Database (Denmark)

    Luczak, M.; Manzato, S.; Peeters, B.

    2011-01-01

    This paper presents some results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study in static and dynamic domains on the bend-twist coupling in the full scale section of a wind turbine blade structure. The main goal of the conducted...... research is to confirm experimentally the numerical prediction of modification of the dynamic and static properties of a wind turbine blade. The bend-twist coupling was implemented by adding angled UD (UniDirectional) layers on the suction and pressure side of the blade. Static and dynamic tests were...... performed on a section of the full scale wind turbine blade provided by VestasWind Systems A/S. The results are presented and compared with the measurements of the original and modified blade. Comparison analysis confirmed that UD layers introduce measurable bend-twist couplings, which was not present...

  15. Operation of Steam Turbines under Blade Failures during the Summer Peak Load Periods

    Directory of Open Access Journals (Sweden)

    Chien-Hsing Lee

    2014-11-01

    Full Text Available This paper presents a discussion of practical experience related to the study of a cogeneration system where one of the four steam units occurs a failure of the low-pressure blades during peak load times of the summer months in Taiwan in the year 2007. This study investigates various scenarios consisting of shutting down the damaged unit for repairs and having continued operation of the unit by removing the low-pressure blades and replacing the stationary blade ring with buffer boards. Based on the simulation results, the numerical model has reflected strong agreement with the critical decisions made to operate the damaged unit continuously in a time of the blade failure.

  16. Tiltrotor research aircraft composite blade repairs: Lessons learned

    Science.gov (United States)

    Espinosa, Paul S.; Groepler, David R.

    1991-01-01

    The XV-15, N703NA Tiltrotor Research Aircraft located at the NASA Ames Research Center, Moffett Field, California, currently uses a set of composite rotor blades of complex shape known as the advanced technology blades (ATBs). The main structural element of the blades is a D-spar constructed of unidirectional, angled fiberglass/graphite, with the aft fairing portion of the blades constructed of a fiberglass cross-ply skin bonded to a Nomex honeycomb core. The blade tip is a removable laminate shell that fits over the outboard section of the spar structure, which contains a cavity to retain balance weights. Two types of tip shells are used for research. One is highly twisted (more than a conventional helicopter blade) and has a hollow core constructed of a thin Nomex-honeycomb-and-fiberglass-skin sandwich; the other is untwisted with a solid Nomex honeycomb core and a fiberglass cross-ply skin. During initial flight testing of the blades, a number of problems in the composite structure were encountered. These problems included debonding between the fiberglass skin and the honeycomb core, failure of the honeycomb core, failures in fiberglass splices, cracks in fiberglass blocks, misalignment of mated composite parts, and failures of retention of metal fasteners. Substantial time was spent in identifying and repairing these problems. Discussed here are the types of problems encountered, the inspection procedures used to identify each problem, the repairs performed on the damaged or flawed areas, the level of criticality of the problems, and the monitoring of repaired areas. It is hoped that this discussion will help designers, analysts, and experimenters in the future as the use of composites becomes more prevalent.

  17. Surgical Procedures of the Elbow: A Nationwide Cross-Sectional Observational Study in the United States

    Directory of Open Access Journals (Sweden)

    Ahmet Kinaci

    2015-01-01

    Full Text Available Background:  Elbow surgery is shared by several subspecialties. We were curious about the most common elbow surgeries and their corresponding diagnoses in the United States.   Methods:  We used the National Hospital Discharge Survey (NHDS and the National Survey of Ambulatory Surgery (NSAS data gathered in 2006-databases that together provide an estimate of all inpatient and ambulatory surgical care in the US.  Results:  An estimated 150,000 elbow surgeries were performed in the US in 2006, 75% in an outpatient setting. The most frequent diagnosis treated operative was enthesopathy (e.g. lateral epicondylitis and it was treated with several different procedures. More than three quarters of all elbow surgeries treated enthesopathy, cubital tunnel syndrome, or fracture (radial head in particular. Arthroscopy and arthroplasty accounted for less than 10% of all elbow surgeries.  Conclusions:  Elbow surgery in the United States primarily addresses enthesopathies such as tennis elbow, cubital tunnel syndrome, and trauma. It is notable that some of the most common elbow surgeries (those that address enthesopathy and radial head fracture are some of the most variably utilized and debated.

  18. Design for the automation of composite wind turbine blade manufacture

    Science.gov (United States)

    Polcari, M. J.; White, K. D.; Sherwood, J. A.

    2016-10-01

    The majority of large wind turbine blades are manufactured from textile-reinforced resin-infused composites using an open mold. The placement of the textile reinforcements in the mold is traditionally accomplished by a manual process where dozens of workers hand place each dry fabric in the mold. Depending on the level of skill and experience of each worker and the relative complexity of the mold geometry, local areas may exhibit out-of-plane wrinkling and in-plane waviness. Fabric imperfections such as these can adversely impact the strength and stiffness of the blade, thereby compromising its durability in service. In an effort to reduce the variabilities associated with a manual-labor process, an automated piecewise shifting method has been proposed for fabric placement. This automated layup method saves time on the preform process and reduces variability from blade to blade. In the current research the automated shifting layup method is investigated using a robust and easy-to-use finite element modelling approach. User-defined material models utilizing a mesoscopic unit-cell modeling approach are linked with Abaqus to capture the evolution of the fabric shear stiffness and changes in the fiber orientations during the fabric-placement process. The simulation approach is demonstrated for the geometry of the trailing edge of a typical wind turbine blade. The simulation considers the mechanical behavior of the fabric and reliably predicts fabric deformation and failure zones.

  19. Efficient Beam-Type Structural Modeling of Rotor Blades

    DEFF Research Database (Denmark)

    Couturier, Philippe; Krenk, Steen

    2015-01-01

    The present paper presents two recently developed numerical formulations which enable accurate representation of the static and dynamic behaviour of wind turbine rotor blades using little modeling and computational effort. The first development consists of an intuitive method to extract fully...... coupled six by six cross-section stiffness matrices with limited meshing effort. Secondly, an equilibrium based beam element accepting directly the stiffness matrices and accounting for large variations in geometry and material along the blade is presented. The novel design tools are illustrated...

  20. Stacking optimization of compressor blades of gas turbine engines

    Science.gov (United States)

    Cheu, Tsu-Chien

    1990-01-01

    A procedure is presented to obtain optimal designs of axial compressor blades with structural design constraints. Coefficients of the polynomials defining the circumferential tilting angles and the axial leaning distances of the airfoil cross sections from the initial design geometry are used as design variables. The compressor blades are modeled by 20-node solid elements. An efficient finite element method is developed for modal analysis and sensitivity analysis with respect to the design variables. Based on this information, a sequential linear programming method is applied to calculate the required change of geometry for the desired structural design constraints.

  1. Non destructive evaluation of wind turbine blades using line scanning thermography

    Energy Technology Data Exchange (ETDEWEB)

    Ley, O.; Godinez, V. [Mistras Group, Princeton Junction, New Jersey (United States)

    2013-05-15

    The increasing energy demand and the need for clean power generation has lead to the improvement of wind turbines and the development of non invasive inspection techniques for the assessment of the blades to avoid catastrophic failures. Given the complexity of the blade geometry, the material composition and material thicknesses, finding a NDT technique to effectively and rapidly inspect the blades to find manufacturing defects or in-service cracks and delaminations is a challenging task. Wind turbine blades are fabricated using layers of different materials bonded together; inspection of the bond quality between external layers and structural elements is fundamental to maintain long term reliability as well as the blade. This paper describes our efforts towards the applications of Line Scanning Thermography (LST) for the analysis of the characteristics of sections of a wind turbine blade like leading and trailing edge, and some fabricated coupons with similar geometries and material characteristics as such sections. The LST technique has provided a quick and efficient methodology to scan large composite structures, which makes it desirable for the inspection of wind turbine blades. Given the material composition in wind turbine blades, the scanning protocols commonly used for inspecting composites with LST had to be modified. The scanning protocols developed for the detection of subsurface disbonds (delamination) will be discussed. (author)

  2. Fabrication of low-cost Mod-OA wood composite wind turbine blades

    Science.gov (United States)

    Lark, R. F.; Gougeon, M.; Thomas, G.; Zuteck, M.

    1983-02-01

    The wood composite blades were fabricated by using epoxy resin-bonded laminates of Douglas fir veneers for the leading edge spar sections and honeycomb-cored birch plywood panels for the blade trailing edge or afterbody sections. The blade was joined to the wind turbine hub assembly by epoxy resin-bonded steel load take-off studs. The wood composite blades were installed in the Mod-OA wind turbine test facility at Kahuku, Hawaii. The wood composite blades have successfully completed high power (average of 150 kW) operations for an eighteen month period (nearly 8,000 hr) before replacement with another set of wood composite blades. The original set of blades was taken out of service because of the failure of the shank on one stud. An inspection of the blades at NASA-Lewis showed that the shank failure was caused by a high stress concentration at a corrosion pit on the shank fillet radius which resulted in fatigue stresses in excess of the endurance limit.

  3. Family satisfaction with patient care in critical care units in Pakistan: a descriptive cross-sectional study.

    Science.gov (United States)

    Ahtisham, Younas; Subia, Parveen; Gideon, Victor

    2016-11-23

    To assess family satisfaction with care provided to patients in critical care units in Islamabad. A descriptive cross-sectional study was conducted in 11 medical and surgical critical care units at two private hospitals in Islamabad, Pakistan. The purposive sample consisted of 323 immediate family members and other relatives and friends (referred to as family members in this article) of 323 patients admitted to the critical care units for at least 24 hours. The revised Critical Care Family Satisfaction Survey was used for data collection. Descriptive statistics were used for data analysis. A total of 149/323 (46%) family members were 'very satisfied' with the honesty (openness) of staff in explaining the patient's condition, and 137/323 (42%) family members were 'very satisfied' with the nurses' availability to speak to them. A total of 143/323 (44%) family members were 'satisfied' with the honesty (openness) of staff in explaining the patient's condition, and 131/323 (41%) were 'satisfied' with the nurses' availability to speak to them. A few family members (21/323, 6%) were 'very dissatisfied' with the flexibility of the visiting hours and a few (20/323, 6%) were 'very dissatisfied' with the noise level in the critical care units. Some family members (38/323, 12%) were 'not satisfied' with the flexibility of the visiting hours, and some (18/323, 6%) were 'not satisfied' with the noise level in the critical care units. The majority of family members (244/323, 75%) were 'satisfied' or 'very satisfied' that their relatives' needs were being met in the critical care units. However, qualitative data indicate that most family members wanted greater involvement in decision making. These findings should be considered by staff working in critical care settings to ensure high-quality patient care.

  4. Cesarean Sections

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Cesarean Sections (C-Sections) KidsHealth > For Parents > Cesarean Sections (C-Sections) A A A What's in this ... babies in the United States are delivered via cesarean section (C-section). Even if you're envisioning a ...

  5. Vibration Characteristics of Aircraft Engine-Bladed-Disk Assembly

    Directory of Open Access Journals (Sweden)

    J. S. Rao

    1986-01-01

    Full Text Available This paper is concerned with the vibration characteristics of a gas-turbine blade-disk assembly and a third stage of compressor blade-disk assembly of an orpheus aircraft engine. The assembly is analyzed by considering each component individually and then combining them together with a receptance coupling technique by matching forces and displacements at each junction point. The blade is modelled by number of free-free aerofoil section beams staggered at different angles to the plane of the disk, and the non-uniform disk is modelled as numbers of concentric annuli. The natural frequencies and mode shapes for each case have been obtained. Results obtained are verified by testing both the above assemblies on a microprocessor based vibration exciter and real time analyzer. The mode shape corresponding to each natural frequency was obtained by probing with hand held accelerometer.

  6. Blade tip vortex measurements on actively twisted rotor blades

    Science.gov (United States)

    Bauknecht, André; Ewers, Benjamin; Schneider, Oliver; Raffel, Markus

    2017-05-01

    Active rotor control concepts, such as active twist actuation, have the potential to effectively reduce the noise and vibrations of helicopter rotors. The present study focuses on the experimental investigation of active twist for the reduction of blade-vortex interaction (BVI) effects on a model rotor. Results of a large-scale smart-twisting active rotor test under hover conditions are described. This test investigated the effects of individual blade twist control on the blade tip vortices. The rotor blades were actuated with peak torsion amplitudes of up to 2° and harmonic frequencies of 1-5/rev with different phase angles. Time-resolved stereoscopic particle image velocimetry was carried out to study the effects of active twist on the strength and trajectories of the tip vortices between ψ _ {v}= 3.6° and 45.7° of vortex age. The analysis of the vortex trajectories revealed that the 1/rev active twist actuation mainly caused a vertical deflection of the blade tip and the corresponding vortex trajectories of up to 1.3% of the rotor radius R above and -1%R below the unactuated condition. An actuation with frequencies of 2 and 3/rev significantly affected the shapes of the vortex trajectories and caused negative vertical displacements of the vortices relative to the unactuated case of up to 2%R within the first 35° of wake age. The 2 and 3/rev actuation also had the most significant effects on the vortex strength and altered the initial peak swirl velocity by up to -34 and +31% relative to the unactuated value. The present aerodynamic investigation reveals a high control authority of the active twist actuation on the strength and trajectories of the trailing blade tip vortices. The magnitude of the evoked changes indicates that the active twist actuation constitutes an effective measure for the mitigation of BVI-induced noise on helicopters.

  7. Aerodynamic Analysis of Morphing Blades

    Science.gov (United States)

    Harris, Caleb; Macphee, David; Carlisle, Madeline

    2016-11-01

    Interest in morphing blades has grown with applications for wind turbines and other aerodynamic blades. This passive control method has advantages over active control methods such as lower manufacturing and upkeep costs. This study has investigated the lift and drag forces on individual blades with experimental and computational analysis. The goal has been to show that these blades delay stall and provide larger lift-to-drag ratios at various angles of attack. Rigid and flexible airfoils were cast from polyurethane and silicone respectively, then lift and drag forces were collected from a load cell during 2-D testing in a wind tunnel. Experimental data was used to validate computational models in OpenFOAM. A finite volume fluid-structure-interaction solver was used to model the flexible blade in fluid flow. Preliminary results indicate delay in stall and larger lift-to-drag ratios by maintaining more optimal angles of attack when flexing. Funding from NSF REU site Grant EEC 1358991 is greatly appreciated.

  8. Damped structural dynamics models of large wind-turbine blades including material and structural damping

    Energy Technology Data Exchange (ETDEWEB)

    Chortis, D I; Chrysochoidis, N A; Saravanos, D A [Department of Mechanical Engineering and Aeronautics, University of Patras, Patras 26500 (Greece)

    2007-07-15

    The paper presents a brief description of composite damping mechanics for blade sections of arbitrary lamination and geometry. A damped 3-D shear beam element is presented enabling the assembly of damped structural dynamic models of blades with hollow multi-cell tubular laminated sections. Emphasis is placed to the inclusion of composite material coupling effects, first in the blade section stiffness and damping matrices and finally into the stiffness and damping matrices of the finite element. Evaluations of the beam element are presented, to quantify the material coupling effect on composite beams of simple box sections. Correlations between predicted and measured modal frequencies and damping values in small model Glass/Epoxy are also shown. Finally, the damped modal characteristics of a 35m realistic wind-turbine blade model design, are predicted.

  9. Work with visual display units and musculoskeletal disorders: A cross-sectional study

    Directory of Open Access Journals (Sweden)

    Matteo Riccò

    2016-12-01

    Full Text Available Background: Epidemiological studies have shown that employees working with visual display units (VDU are more likely to complain about musculoskeletal disorders (MSDs. The aim of this study has been to evaluate associations among MSDs and individuals and work-related factors. Material and Methods: A total of 1032 VDU workers were assessed about their personal (i.e., age, working history, smoking history, physical activity and work-related factors (i.e., predominant job tasks performed, work posture. Work environment was evaluated regarding fulfillment of the standard ISO 9241-5:1998. The investigation required a direct observation of participants (in order to accurately assess the prevalence of MSDs and workstations. Adjusted odds ratios (ORa were calculated by means of the logistic regression model. Results: Prevalence of MSDs was relatively high (53%. In general, MSDs were significantly associated with female sex (OR = 2.832, 95% confidence interval (CI: 2.178–3.683, age ≥ 50 years old (OR = 2.231, 95% CI: 1.236–4.026, longer exposure to VDU, both as working history (10–14 years: OR = 1.934, 95% CI: 1.301–2.875; ≥ 15 years: OR = 2.223, 95% CI: 1.510–3.271 and working time (30–39 h/week: OR = 1.537, 95% CI: 1.087–2.273. Inappropriate workstation design was confirmed by the multivariate analysis as a risk factor for MSDs (ORa = 2.375, 95% CI: 1.124–5.018. Conclusions: Musculoskeletal disorders were significantly associated with individual factors as well as characteristics of work environment. An appropriate design of workstations may significantly reduce their prevalence amongst VDU workers. Med Pr 2016;67(6:707–719

  10. Work with visual display units and musculoskeletal disorders: A cross-sectional study.

    Science.gov (United States)

    Riccò, Matteo; Cattani, Silvia; Gualerzi, Giovanni; Signorelli, Carlo

    2016-12-22

    Epidemiological studies have shown that employees working with visual display units (VDU) are more likely to complain about musculoskeletal disorders (MSDs). The aim of this study has been to evaluate associations among MSDs and individuals and work-related factors. A total of 1032 VDU workers were assessed about their personal (i.e., age, working history, smoking history, physical activity) and work-related factors (i.e., predominant job tasks performed, work posture). Work environment was evaluated regarding fulfillment of the standard ISO 9241-5:1998. The investigation required a direct observation of participants (in order to accurately assess the prevalence of MSDs) and workstations. Adjusted odds ratios (ORa) were calculated by means of the logistic regression model. Prevalence of MSDs was relatively high (53%). In general, MSDs were significantly associated with female sex (OR = 2.832, 95% confidence interval (CI): 2.178-3.683), age ≥ 50 years old (OR = 2.231, 95% CI: 1.236-4.026), longer exposure to VDU, both as working history (10-14 years: OR = 1.934, 95% CI: 1.301-2.875; ≥ 15 years: OR = 2.223, 95% CI: 1.510-3.271) and working time (30-39 h/week: OR = 1.537, 95% CI: 1.087-2.273). Inappropriate workstation design was confirmed by the multivariate analysis as a risk factor for MSDs (ORa = 2.375, 95% CI: 1.124-5.018). Musculoskeletal disorders were significantly associated with individual factors as well as characteristics of work environment. An appropriate design of workstations may significantly reduce their prevalence amongst VDU workers. Med Pr 2016;67(6):707-719.

  11. Implementation of the Generalized Brazier Effect in Analysis of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Lauridsen, Peter Riddersholm; Nikolajsen, Jan Ánike; Damkilde, Lars

    2016-01-01

    As wind turbine blades are getting longer and more slender, new failure modes occur and these may be related to the non-linear geometric Brazier effect1,2,3, where the bending moments ovalize the thin-walled cross-sections. For general cross-sections the torsional moments have a similar effect....... The accuracy of the proposed method has been illustrated on a wind turbine blade from SSP Technology A/S....

  12. Structural damage identification in wind turbine blades using piezoelectric active sensing with ultrasonic validation

    Energy Technology Data Exchange (ETDEWEB)

    Claytor, Thomas N [Los Alamos National Laboratory; Ammerman, Curtt N [Los Alamos National Laboratory; Park, Gyu Hae [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Farrar, Charles R [Los Alamos National Laboratory; Atterbury, Marie K [Los Alamos National Laboratory

    2010-01-01

    This paper gives a brief overview of a new project at LANL in structural damage identification for wind turbines. This project makes use of modeling capabilities and sensing technology to understand realistic blade loading on large turbine blades, with the goal of developing the technology needed to automatically detect early damage. Several structural health monitoring (SHM) techniques using piezoelectric active materials are being investigated for the development of wireless, low power sensors that interrogate sections of the wind turbine blade using Lamb wave propagation data, frequency response functions (FRFs), and time-series analysis methods. The modeling and sensor research will be compared with extensive experimental testing, including wind tunnel experiments, load and fatigue tests, and ultrasonic scans - on small- to mid-scale turbine blades. Furthermore, this study will investigate the effect of local damage on the global response of the blade by monitoring low-frequency response changes.

  13. Model predictive control of trailing edge flaps on a wind turbine blade

    DEFF Research Database (Denmark)

    Castaignet, Damien Bruno

    , in Roskilde, Denmark. One blade of the turbine was equipped with three independent trailing edge flaps. In spite of the failure of several sensors and actuators, the test of the trailing edge flaps controller described in this thesis showed a consistent flapwise blade root fatigue load reduction. An average......Trailing edge flaps on wind turbine blades have been investigated for several years. Aero-servoelastic simulations carried out with different simulation tools, trailing edge flaps configurations and controller designs proved that trailing edge flaps are a suitable solution for reducing some...... of the wind turbine fatigue and extreme loads. This potential was confirmed with wind tunnel tests made on blade sections with trailing edge flaps and on a scaled two-bladed wind turbine in a wind tunnel. The work presented in this thesis includes a full-scale test run on a Vestas V27 wind turbine equipped...

  14. POD based analysis of three-dimensional stall over a pitching wind turbine blade

    Science.gov (United States)

    Melius, Matthew; Bayoan Cal, Raul; Mulleners, Karen

    2015-11-01

    Aerodynamic performance of a wind turbine blade is a predominant factor in its power production. Under dynamic loading conditions, predicted aerodynamic loads often do not match operational loads. In the interest of gaining understanding of the complex flow over wind turbine blades, a three-dimensional scaled blade model has been designed and manufactured to be dynamically similar to a rotating full-scale NREL 5MW wind turbine blade. Time resolved particle image velocimetry (PIV) measurements collected over the suction surface of an inboard section of the experimental turbine blade. Flow characteristics are analyzed using coherent structure identification techniques to capture dynamic stall behavior. Proper orthogonal decomposition (POD) is applied to the velocity field providing information about separation point and stall development time scales based on the associated time coefficients and modes. Additionally, continuity and circulation calculations are used to capture three dimensional effects within stalled volumes during developing stall and re-attachment phases of dynamic stall.

  15. EFFECTS OF SPLITTER BLADES ON THE LAW OF INNER FLOW WITHIN CENTRIFUGAL PUMP IMPELLER

    Institute of Scientific and Technical Information of China (English)

    YUAN Shouqi; ZHANG Jinfeng; YUAN Jianping; HE Youshi; FU Yuedeng

    2007-01-01

    Analysis on the inner flow field of a centrifugal pump impeller with splitter blades is carried out by numerical simulation. Based on this analysis, the principle of increasing pump head and efficiency are discussed. New results are obtained from the analysis of turbulence kinetic energy and relative velocity distribution: Firstly, unreasonable length or deviation design of the splitter blades may cause great turbulent fluctuation in impeller channel, which has a great effect on the stability of impeller outlet flow; Secondly, it is found that the occurrence of flow separation can be decreased or delayed with splitter blades from the analysis of blade loading; Thirdly, the effect of splitter blades on reforming the structure of "jet-wake" is explained from the relative velocity distribution at different flow cross-sections, which shows the flow process in the impeller. The inner flow analysis verifies the results of performance tests results and the PIV test.

  16. Investigation of fatigue fracture of generator-rotor fan blades

    Energy Technology Data Exchange (ETDEWEB)

    Sameezadeh, Mahmood; Farhangi, Hassan [School of Metallurgy and Materials Engineering, Univ. of Tehran (Iran); Soltani, Nasser [School of Mechanical Engineering, Univ. of Tehran (Iran); Ataei, Peyman [Dept. of Metallurgy and Materials Engineering, South Tehran Branch of Azad Univ., Tehran (Iran)

    2009-11-15

    The failure of a rotating axial flow fan of a 123 MW electric power generator unit is analyzed. The fan was mounted on the generator-rotor at the turbine end. Initial investigations showed that three fan blades had fractured just about 11 h after resuming operation following the last overhaul, causing extensive damage to the unit. The failure of the blades was investigated using fractographic and microstructural characterization techniques as well as mechanical evaluations. Based on fractographic observations high cycle fatigue was identified as the failure mechanism. Formation of multiple primary cracks which coalesced during crack growth to form shallow and semi-elliptical crack geometry was indicative of the influence of additional bending stresses, probably resulting from excessive vibrations. Using fracture mechanics principles, the magnitude of the maximum stress at the time of final fracture of the first broken blade was estimated to be more than 3 times higher than the design operating stress. Furthermore, crack growth lifetime of the blades was evaluated using FRANC3D software. It was found that an operating period of just about one hour was required for small initial cracks to propagate to final failure under the action of excessive bending stresses. (orig.)

  17. A comparison of model helicopter rotor Primary and Secondary blade/vortex interaction blade slap

    Science.gov (United States)

    Hubbard, J. E., Jr.; Leighton, K. P.

    1983-01-01

    A study of the relative importance of blade/vortex interactions which occur on the retreating side of a model helicopter rotor disk is described. Some of the salient characteristics of this phenomenon are presented and discussed. It is shown that the resulting Secondary blade slap may be of equal or greater intensity than the advancing side (Primary) blade slap. Instrumented model helicopter rotor data is presented which reveals the nature of the retreating blade/vortex interaction. The importance of Secondary blade slap as it applies to predictive techniques or approaches is discussed. When Secondary blade slap occurs it acts to enlarge the window of operating conditions for which blade slap exists.

  18. Development of advanced blade pitching kinematics for cycloturbines and cyclorotors

    Science.gov (United States)

    Adams, Zachary Howard

    to achieve optimum performance. A novel inverse method was developed implementing a new semi-empirical curvilinear flow blade aerodynamic coefficient model to predict optimum cycloturbine blade pitch waveforms from the ideal fluid deceleration. These improved blade pitch waveforms were evaluated on a 1.37m diameter by 1.37m span cycloturbine to definitively characterize their improvement over existing blade pitch motions and demonstrate the practicality of a variable blade pitch system. The Fluxline Optimal pitching kinematics outperformed sinusoidal and fixed pitching kinematics. The turbine achieved a mean gross aerodynamic power coefficient of 0.44 (95% confidence interval: [0.388,0.490]) and 0.52 (95% confidence interval: [0.426,0.614]) at tip speed ratios (TSRs) of 1.5 and 2.25 respectively which exceeds all other low TSR vertical axis wind turbines. Two-dimensional incompressible Reynolds-averaged Navier-Stokes computational fluid dynamic simulations were used to characterize higher order effects of the blade interaction with the fluid. These simulations suggest Fluxline Optimal pitch kinematics achieve high power coefficients by evenly extracting energy from the flow without blade stall or detached turbine wakes. Fluxline Theory was adapted to inform the design of high efficiency cyclorotors by incorporating the concept of rotor angle of attack as well as a power and drag loss model for blade support structure. A blade element version of this theory predicts rotor performance. For hovering, a simplified variation of the theory instructs that cyclorotors will achieve the greatest power loading at low disk loadings with high solidity blades pitched to maximum lift coefficient. Increasing lift coefficients in the upstream portion of the rotor disproportionately increases performance compared to magnifying lift in the downstream portion. This suggests airfoil sections that counter curvilinear flow effects could improve hovering efficiency. Additionally, the

  19. Wind Turbine Blade with Angled Girders

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a reinforced blade for a wind turbine, particularly to a blade having a new arrangement of two or more girders in the blade, wherein each of the girders is connected to the upper part and the lower part of the shell and forms an angle with another girder thereby...

  20. Individual blade pitch for yaw control

    NARCIS (Netherlands)

    Navalkar, S.T.; Van Wingerden, J.W.; Van Kuik, G.A.M.

    2014-01-01

    Individual pitch control (IPC) for reducing blade loads has been investigated and proven successful in recent literature. For IPC, the multi-blade co-ordinate (MBC) transformation is used to process the blade load signals from the rotating to a stationary frame of reference. In the stationary frame

  1. Individual blade pitch for yaw control

    NARCIS (Netherlands)

    Navalkar, S.T.; Van Wingerden, J.W.; Van Kuik, G.A.M.

    2014-01-01

    Individual pitch control (IPC) for reducing blade loads has been investigated and proven successful in recent literature. For IPC, the multi-blade co-ordinate (MBC) transformation is used to process the blade load signals from the rotating to a stationary frame of reference. In the stationary frame

  2. Wind Turbine Blade with Angled Girders

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a reinforced blade for a wind turbine, particularly to a blade having a new arrangement of two or more girders in the blade, wherein each of the girders is connected to the upper part and the lower part of the shell and forms an angle with another girder thereby...

  3. Three-dimensional turbine blade design using a Navier-Stokes solver and Artificial Neural Network

    Energy Technology Data Exchange (ETDEWEB)

    Pierret, S.; Braembussche, R.A. van den [Von Karman Institute, Rhode-Saint-Genese (Belgium)

    1999-07-01

    Improving turbine efficiency by applying non-radial stacking and three-dimensional design techniques has received considerable attention in the recent years. A big source of losses is the spanwise non-uniformity of the next stage inlet flow angle resulting form the non-uniformity of the outlet flow angle of the preceding blade row. This non-uniformity can be reduced by adjusting the 2D sections along the span and/or by leaning the blades. The present method describes the design of a 3D blade geometry built by a radial stacking of several 2D blade sections which are provided by a 2D design system. A 3D Navier-Stokes solver is used to check the blade performance and to update the requirements imposed for the next design of the 2D blade sections. The 2D sections are designed using an Artificial Neural Network (ANN). The latter one constructs an approximate model (response surface) using a database containing the 2D Navier-Stokes solutions obtained from previous designs. It is used for the optimisation of the 2D blade geometry by means of Simulated Annealing (SA). The optimum 2D geometry is then verified by a 2D Navier-Stokes solver. This procedure results in a considerable speed-up of the design process by reducing both the interventions of the operator and the computational effort. It also allows the design of more efficient blades, satisfying both the aerodynamic and mechanical constraints. The method has been used to design different types of turbine blades of which one example will be presented. (Author)

  4. An acoustic-array based structural health monitoring technique for wind turbine blades

    Science.gov (United States)

    Aizawa, Kai; Poozesh, Peyman; Niezrecki, Christopher; Baqersad, Javad; Inalpolat, Murat; Heilmann, Gunnar

    2015-04-01

    This paper proposes a non-contact measurement technique for health monitoring of wind turbine blades using acoustic beamforming techniques. The technique works by mounting an audio speaker inside a wind turbine blade and observing the sound radiated from the blade to identify damage within the structure. The main hypothesis for the structural damage detection is that the structural damage (cracks, edge splits, holes etc.) on the surface of a composite wind turbine blade results in changes in the sound radiation characteristics of the structure. Preliminary measurements were carried out on two separate test specimens, namely a composite box and a section of a wind turbine blade to validate the methodology. The rectangular shaped composite box and the turbine blade contained holes with different dimensions and line cracks. An acoustic microphone array with 62 microphones was used to measure the sound radiation from both structures when the speaker was located inside the box and also inside the blade segment. A phased array beamforming technique and CLEAN-based subtraction of point spread function from a reference (CLSPR) were employed to locate the different damage types on both the composite box and the wind turbine blade. The same experiment was repeated by using a commercially available 48-channel acoustic ring array to compare the test results. It was shown that both the acoustic beamforming and the CLSPR techniques can be used to identify the damage in the test structures with sufficiently high fidelity.

  5. Feasibility of using line scanning thermography in NDE of wind turbine blades

    Science.gov (United States)

    Ley, Obdulia; Godinez, Valery

    2011-04-01

    Today, the increasing energy demand and the need for clean power generation has lead to the improvement of wind turbines and the development non invasive inspection techniques for the assessment of wind turbine blades to maintain long term reliability as well as to avoid catastrophic failures. Given the complexity of the geometry, the material composition and material thicknesses, finding a NDT technique to effectively and rapidly inspect the blades is a challenging task. Wind turbine blades are fabricated using different materials like fiber glass, carbon composites, foam and/ or balsa wood. Layers of these materials are bonded together using an epoxy type resin. Inspection of the bond quality between external layers and structural elements of the blade is of fundamental importance for quality control and service of the blade. In this study our efforts towards the applications of Line Scanning Thermography (LST) for the analysis of test coupons fabricated using the materials employed in the manufacture of wind turbine blades, as well as some wind turbine blade sections. LST utilizes a line heat source to thermally excite the surface to be inspected and an infrared detector to record the transient surface temperature variation produced by disbonds, and other subsurface imperfections. The LST technique has provided a quick and efficient methodology to scan large composite structures, which makes it desirable for the inspection of wind turbine blades. The scanning protocols developed for the detection of sub-surface disbonds (delamination) in coupons and parts will be presented. The successes and limitations of the technique will be discussed.

  6. Piercing the water surface with a blade: Singularities of the contact line

    Energy Technology Data Exchange (ETDEWEB)

    Alimov, Mars M. [Kazan Federal University, Kazan 420008 (Russian Federation); Kornev, Konstantin G. [Department of Materials Science & Engineering, Clemson University, Clemson, South Carolina 29634 (United States)

    2016-01-15

    An external meniscus on a narrow blade with a slit-like cross section is studied using the hodograph formulation of the Laplace nonlinear equation of capillarity. On narrow blades, the menisci are mostly shaped by the wetting and capillary forces; gravity plays a secondary role. To describe a meniscus in this asymptotic case, the model of Alimov and Kornev [“Meniscus on a shaped fibre: Singularities and hodograph formulation,” Proc. R. Soc. A 470, 20140113 (2014)] has been employed. It is shown that at the sharp edges of the blade, the contact line makes a jump. In the wetting case, the contact line sitting at each side of the blade is lifted above the points where the meniscus first meets the blade edges. In the non-wetting case, the contact line is lowered below these points. The contours of the constant height emanating from the blade edges generate unusual singularities with infinite curvatures at some points at the blade edges. The meniscus forms a unique surface made of two mirror-symmetric sheets fused together. Each sheet is supported by the contact line sitting at each side of the blade.

  7. An Analytical Model to Extract Wind Turbine Blade Structural Properties for Optimization and Up-scaling Studies

    NARCIS (Netherlands)

    Ashuri, T.; Van Bussel, G.J.W.; Zaayer, M.B.; Van Kuik, G.A.M.

    2010-01-01

    A wind turbine blade has a complex shape and consists of different elements with dissimilar material properties. To do any aeroelastic simulation, the structural properties of the blade such as stiffnesses and mass per unit length should be known in advance, and extracting these properties is a diff

  8. MEASUREMENT OF ENDOTRACHEAL TUBE CUFF PRESSURE IN MECHANICALLYVENTILATED PATIENTS ON ARRIVAL TO INTENSIVE CARE UNIT - A CROSS-SECTIONAL STUDY

    Directory of Open Access Journals (Sweden)

    Arun Kumar Ajjappa

    2017-04-01

    Full Text Available BACKGROUND The monitoring of Endotracheal Tube (ETT cuff pressure in intubated patients on arrival to intensive care unit is very essential. The cuff pressure must be within an optimal range of 20-30cm H2O ensuring ventilation with no complications related to cuff overinflation and underinflation. This can be measured with a cuff pressure manometer. The aim of the study is to measure the endotracheal tube cuff pressure in patients on arrival to intensive care unit and to identify prevalence of endotracheal cuff underinflation and overinflation. MATERIALS AND METHODS A cross-sectional study was done on mechanically-ventilated patients who were intubated in casualty (emergency department on arrival to intensive care unit in S.S. Institute of Medical Sciences and Research Centre, Davangere. About 50 critically-ill patients intubated with a high volume, low pressure endotracheal tube were included in the study. An analogue manometer was used to measure the endotracheal tube cuff pressure. It was compared with the recommended level. The settings of mechanical ventilation, endotracheal tube size and peak airway pressure were recorded. RESULTS It was found that the mean cuff pressure was 64.10 cm of H2O with a standard deviation of 32.049. Of the measured cuff pressures, only 2% had pressures within an optimal range (20-30cm of H2O. 88% had cuff pressures more than 30cm of H2O. The mean peak airway pressure found to be 20.50cm of H2O with a Standard Deviation (SD of 5.064. CONCLUSION This study is done to emphasise the importance of cuff pressure measurement in all mechanically-ventilated patients as cuff pressure is found to be high in most of the patients admitted to intensive care unit. Complications of overinflation and underinflation can only be prevented if the acceptable cuff pressures are achieved.

  9. A Microwave Blade Tip Clearance Sensor for Propulsion Health Monitoring

    Science.gov (United States)

    Woike, Mark R.; Abdul-Aziz, Ali; Bencic, Timothy J.

    2010-01-01

    Microwave sensor technology is being investigated by the NASA Glenn Research Center as a means of making non-contact structural health measurements in the hot sections of gas turbine engines. This type of sensor technology is beneficial in that it is accurate, it has the ability to operate at extremely high temperatures, and is unaffected by contaminants that are present in turbine engines. It is specifically being targeted for use in the High Pressure Turbine (HPT) and High Pressure Compressor (HPC) sections to monitor the structural health of the rotating components. It is intended to use blade tip clearance to monitor blade growth and wear and blade tip timing to monitor blade vibration and deflection. The use of microwave sensors for this application is an emerging concept. Techniques on their use and calibration needed to be developed. As a means of better understanding the issues associated with the microwave sensors, a series of experiments have been conducted to evaluate their performance for aero engine applications. This paper presents the results of these experiments.

  10. Numerical simulation on vacuum solution heat treatment and gas quenching process of a low rhenium-containing Ni-based single crystal turbine blade

    Directory of Open Access Journals (Sweden)

    Zhe-xin Xu

    2016-11-01

    Full Text Available Numerical heat-transfer and turbulent flow model for an industrial high-pressure gas quenching vacuum furnace was established to simulate the heating, holding and gas fan quenching of a low rhenium-bearing Ni-based single crystal turbine blade. The mesh of simplified furnace model was built using finite volume method and the boundary conditions were set up according to the practical process. Simulation results show that the turbine blade geometry and the mutual shielding among blades have significant influence on the uniformity of the temperature distribution. The temperature distribution at sharp corner, thin wall and corner part is higher than that at thick wall part of blade during heating, and the isotherms show a toroidal line to the center of thick wall. The temperature of sheltered units is lower than that of the remaining part of blade. When there is no shelteration among multiple blades, the temperature distribution for all blades is almost identical. The fluid velocity field, temperature field and cooling curves of the single and multiple turbine blades during gas fan quenching were also simulated. Modeling results indicate that the loading tray, free outlet and the location of turbine blades have important influences on the flow field. The high-speed gas flows out from the nozzle is divided by loading tray, and the free outlet enhanced the two vortex flow at the end of the furnace door. The closer the blade is to the exhaust outlet and the nozzle, the greater the flow velocity is and the more adequate the flow is. The blade geometry has an effect on the cooling for single blade and multiple blades during gas fan quenching, and the effects in double layers differs from that in single layer. For single blade, the cooing rate at thin-walled part is lower than that at thick-walled part, the cooling rate at sharp corner is greater than that at tenon and blade platform, and the temperature at regions close to the internal position is

  11. Composite blade damaging under impact

    NARCIS (Netherlands)

    Menouillard, T.; Réthoré, J.; Bung, H.; Suffis, A.

    2006-01-01

    Composites materials are now being used in primary aircraft structures, and other domains because of numerous advantages. A part of a continuous in-flight operating costs, gas turbine engine manufacturers are always looking for ways to decrease engine weight. This is the case of compressor blades

  12. Experimental Blade Research - phase 2

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Branner, Kim; Berring, Peter

    This report is a summary of the results obtained in the project: Experimental Blade Research – phase 2 (EBR2). The project was supported by the Danish Energy Authority through the 2010 Energy Technology Development and Demonstration Program (EUDP 2010-II) and has journal no. 64011-0006. The project...

  13. Photo Surfing in Blade Runner

    Science.gov (United States)

    Ohler, Jason

    2005-01-01

    This month's "Mining Movies" looks at Blade Runner, Ridley Scott's film set in the year 2019. It is a sad time for Earth, which is in the midst of environmental degradation so severe that other planets are being prepared for colonization. The main source of labor for this preparation work are "replicants," organic robots that look and behave like…

  14. Effects of Blade Boundary Layer Transition and Daytime Atmospheric Turbulence on Wind Turbine Performance Analyzed with Blade-Resolved Simulation and Field Data

    Science.gov (United States)

    Nandi, Tarak Nath

    Relevant to utility scale wind turbine functioning and reliability, the present work focuses on enhancing our understanding of wind turbine responses from interactions between energy-dominant daytime atmospheric turbulence eddies and rotating blades of a GE 1.5 MW wind turbine using a unique data set from a GE field experiment and computer simulations at two levels of fidelity. Previous studies have shown that the stability state of the lower troposphere has a major impact on the coherent structure of the turbulence eddies, with corresponding differences in wind turbine loading response. In this study, time-resolved aerodynamic data measured locally at the leading edge and trailing edge of three outer blade sections on a GE 1.5 MW wind turbine blade and high-frequency SCADA generator power data from a daytime field campaign are combined with computer simulations that mimic the GE wind turbine within a numerically generated atmospheric boundary layer (ABL) flow field which is a close approximation of the atmospheric turbulence experienced by the wind turbine in the field campaign. By combining the experimental and numerical data sets, this study describes the time-response characteristics of the local loadings on the blade sections in response to nonsteady nonuniform energetic atmospheric turbulence eddies within a daytime ABL which have spatial scale commensurate with that of the turbine blade length. This study is the first of its kind where actuator line and blade boundary layer resolved CFD studies of a wind turbine field campaign are performed with the motivation to validate the numerical predictions with the experimental data set, and emphasis is given on understanding the influence of the laminar to turbulent transition process on the blade loadings. The experimental and actuator line method data sets identify three important response time scales quantified at the blade location: advective passage of energy-dominant eddies (≈25 - 50 s), blade rotation (1P

  15. Tests of Two Full-Scale Propellers with Different Pitch Distributions, at Blade Angles up to 60 Degrees

    Science.gov (United States)

    Biermann, David; HARTMAN EDWIN P

    1939-01-01

    Two 3-blade 10-foot propellers were operated in front of a liquid-cooled engine nacelle. The propellers differed only in pitch distribution; one had normal distribution (nearly constant pitch for a blade angle of 15 degrees at 0.75 radius), and the other had the pitch of the tip sections decreased with respect to that for the shank sections (blade angle of 35 degrees for nearly constant pitch distribution). Propeller blade angles at 0.75r from 15 degrees to sixty degrees, corresponding to design speeds up to 500 miles per hour, were investigated. Propeller blade angles at 0.75r from 15 degrees to 60 degrees, corresponding to design speeds up to 500 miles per hour, were investigated. The results indicated that the propulsive efficiency at a blade angle of 60 degrees was about 9 percent less than the maximum value of 86 percent, which occurred at blade angle of about 30 degrees. The efficiency at a blade angle of 60 degrees was increased about 7 percent by correcting for the effect of a spinner and, at a blade angle of 30 degrees about 3 percent. The peak efficiencies for the propeller having the washed-out pitch distribution were slightly less than for the normal propeller but the take-off efficiency was generally higher.

  16. A sectional-splinting technique for impressing multiple implant units by eliminating the use of an open tray

    Directory of Open Access Journals (Sweden)

    Suryakant C. Deogade

    2014-01-01

    Full Text Available Since the inception of root form implant dentistry by P-I Branemark in the early 1980′s, so many technical advances have been put forward by several authors. However, the open tray impression technique is still performed for impressing multiple implant fixtures as it was first described in the original Branemark procedure manual. The most critical aspect for a successful implant-supported restoration is the passive and an accurate fit of superstructures to avoid preload and loading stresses. Splinting impression technique in multiple implants has gained popularity. Auto-polymerizing acrylic resin is among the most routinely practiced splinting material for multiple implant units. However, unfortunately, it exhibits shrinkage, which makes an impression quite inaccurate. This case report presents the solution to minimize the shrinkage of resin by utilizing sectional-splinting technique as advocated in the previous implant literature.

  17. Income distribution and mortality: cross sectional ecological study of the Robin Hood index in the United States.

    Science.gov (United States)

    Kennedy, B P; Kawachi, I; Prothrow-Stith, D

    1996-04-20

    To determine the effect of income inequality as measured by the Robin Hood index and the Gini coefficient on all cause and cause specific mortality in the United States. Cross sectional ecological study. Households in the United States. Disease specific mortality, income, household size, poverty, and smoking rates for each state. The Robin Hood index was positively correlated with total mortality adjusted for age (r = 0.54; P < 0.05). This association remained after adjustment for poverty (P < 0.007), where each percentage increase in the index was associated with' an increase in the total mortality of 21.68 deaths per 100,000. Effects of the index were also found for infant mortality (P = 0.013); coronary heart disease (P = 0.004); malignant neoplasms (P = 0.023); and homicide (P < 0.001). Strong associations were also found between the index and causes of death amenable to medical intervention. The Gini coefficient showed very little correlation with any of the causes of death. Variations between states in the inequality of income were associated with increased mortality from several causes. The size of the gap between the wealthy and less well off--as distinct from the absolute standard of living enjoyed by the poor--seems to matter in its own right. The findings suggest that policies that deal with the growing inequities in income distribution may have an important impact on the health of the population.

  18. Investigation of UWB Wind Turbine Blade Deflection Sensing with a Tip Antenna inside a Blade

    DEFF Research Database (Denmark)

    Zhang, Shuai; Jensen, Tobias Lindstrøm; Franek, Ondrej;

    2016-01-01

    An UWB blade deflection sensing system with a tip antenna inside a blade is investigated in this paper. The lower UWB band of 3.1-5.3 GHz is utilized. This system composes of two UWB radio links between one antenna inside the blade tip and two antennas outside the blade root. Blade deflections ar......, and the sensing system can realize the deflection tracking with a maximum deviation of 0.21 m and root mean squared error of 0.11 m.......An UWB blade deflection sensing system with a tip antenna inside a blade is investigated in this paper. The lower UWB band of 3.1-5.3 GHz is utilized. This system composes of two UWB radio links between one antenna inside the blade tip and two antennas outside the blade root. Blade deflections......-blade time-domain measurements are proposed to verify the simulations and realize the blade deflection sensing with an in-blade tip antenna. With the optimized in-blade tip antenna polarization and two root antenna locations, an accuracy of 2 cm is achieved for the tip-root antenna distance estimation...

  19. Modal testing of the TX-100 wind turbine blade.

    Energy Technology Data Exchange (ETDEWEB)

    Reese, Sarah; Griffith, Daniel Todd; Casias, Miguel; Simmermacher, Todd William; Smith, Gregory A.

    2006-05-01

    This test report covers the SNL modal test results for two nominally identical TX-100 wind turbine blades. The TX-100 blade design is unique in that it features a passive braking, force-shedding mechanism where bending and torsion are coupled to produce desirable aerodynamic characteristics. A specific aim of this test is to characterize the coupling between bending and torsional dynamics. The results of the modal tests and the subsequent analysis characterize the natural frequencies, damping, and mode shapes of the individual blades. The results of this report are expected to be used for model validation--the frequencies and mode shapes from the experimental analysis can be compared with those of a finite-element analysis. Damping values are included in the results of these tests to potentially improve the fidelity of numerical simulations, although numerical finite element models typically have no means of predicting structural damping characteristics. Thereafter, an additional objective of the test is achieved in evaluating the test to test and unit variation in the modal parameters of the two blades.

  20. Losses estimation in transonic wet steam flow through linear blade cascade

    Science.gov (United States)

    Dykas, Sławomir; Majkut, Mirosław; Strozik, Michał; Smołka, Krystian

    2015-04-01

    Experimental investigations of non-equilibrium spontaneous condensation in transonic steam flow were carried out in linear blade cascade. The linear cascade consists of the stator blades of the last stage of low pressure steam turbine. The applied experimental test section is a part of a small scale steam power plant located at Silesian University of Technology in Gliwice. The steam parameters at the test section inlet correspond to the real conditions in low pressure part of 200MWe steam turbine. The losses in the cascade were estimated using measured static pressure and temperature behind the cascade and the total parameters at inlet. The static pressure measurements on the blade surface as well as the Schlieren pictures were used to assess the flow field in linear cascade of steam turbine stator blades.

  1. Damage Identification of Wind Turbine Blades Using Piezoelectric Transducers

    Directory of Open Access Journals (Sweden)

    Seong-Won Choi

    2014-01-01

    Full Text Available This paper presents the experimental results of active-sensing structural health monitoring (SHM techniques, which utilize piezoelectric transducers as sensors and actuators, for determining the structural integrity of wind turbine blades. Specifically, Lamb wave propagations and frequency response functions at high frequency ranges are used to estimate the condition of wind turbine blades. For experiments, a 1 m section of a CX-100 blade is used. The goal of this study is to assess and compare the performance of each method in identifying incipient damage with a consideration given to field deployability. Overall, these methods yielded a sufficient damage detection capability to warrant further investigation. This paper also summarizes the SHM results of a full-scale fatigue test of a 9 m CX-100 blade using piezoelectric active sensors. This paper outlines considerations needed to design such SHM systems, experimental procedures and results, and additional issues that can be used as guidelines for future investigations.

  2. Jet Engine Fan Blade Containment Using an Alternate Geometry

    Science.gov (United States)

    Carney, K.S.; Pereira, J.M.; Revilock, D.M.; Matheny, P.

    2008-01-01

    With a goal of reducing jet engine weight, simulations of a fan blade containment system with an alternate geometry were tested and analyzed. A projectile simulating a fan blade was shot at two alternate geometry containment case configurations using a gas gun. The first configuration was a flat plate representing a standard case configuration. The second configuration was a flat plate with a radially convex curve section at the impact point. The curved surface was designed to force the blade to deform plastically, dissipating energy before the full impact of the blade is received by the plate. The curved case was able to tolerate a higher impact velocity before failure. The computational model was developed and correlated with the tests and a weight savings assessment was performed. For the particular test configuration used in this study the ballistic impact velocity of the curved plate was approximately 60 m/s (200 ft/s) greater than that of the flat plate. For the computational model to successfully duplicate the test, the very high strain rate behavior of the materials had to be incorporated.

  3. Optimisation of Fan Blade Angle

    Directory of Open Access Journals (Sweden)

    Swaroop M P

    2017-01-01

    Full Text Available This report represents the optimization of fan blade angle in accordance with the various room temperatures that can be in the tropical area like India. We took this work mainly because cooling is an important factor now a days in every area where construction and rooms are there and ceiling fans are the most common device that is commonly used. So it is of utmost importance to tweak the performance of this ceiling fan so that it can function in its most optimal condition. We have modeled the fan in a modeling software (SOLIDWORKS and imported that into an analyzing software (ANSYS and a result is generated on the various blade angles (0, 4, 8 and 12.5 degrees in accordance to room conditions. A trend line curve with the obtained data is expected as the result which can be crucial for designing of future fans

  4. Effect of Wavy Trailing Edge on 100meter Flatback Wind Turbine Blade

    Science.gov (United States)

    Yang; Baeder, J. D.

    2016-09-01

    The flatback trailing edge design for modern 100meter wind turbine blade has been developed and proposed to make wind turbine blade to be slender and lighter. On the other hand, it will increase aerodynamic drag; consequently the increased drag diminishes turbine power generation. Thus, an aerodynamic drag reducing technique should be accompanied with the flatback trailing edge in order to prevent loss of turbine power generation. In this work, a drag mitigation design, span-wise wavy trailing edge blade, has been applied to a modern 100meter blade. The span-wise trailing edge acts as a vortex generator, and breaks up the strong span-wise coherent trailing edge vortex structure at the flatback airfoil trailing edge which is a major source of large drag. Three-dimensional unsteady Computational Fluid Dynamics (CFD) simulations have been performed for real scale wind turbine blade geometries. Delayed Detached Eddy Simulation (DDES) with the modified laminar-turbulent transition model has been applied to obtain accurate flow field predictions. Graphical Processor Unit (GPU)-accelerated computation has been conducted to reduce computational costs of the real scale wind turbine blade simulations. To verify the structural reliability of the wavy modification of the blade a simple Eigen buckling analysis has been performed in the current study.

  5. Towing Tank and Flume Testing of Passively Adaptive Composite Tidal Turbine Blades: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Robynne [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-09-28

    Composite tidal turbine blades with bend-twist (BT) coupled layups allow the blade to self-adapt to local site conditions by passively twisting. Passive feathering has the potential to increase annual energy production and shed thrust loads and power under extreme tidal flows. Decreased hydrodynamic thrust and power during extreme conditions meann that the turbine support structure, generator, and other components can be sized more appropriately, resulting in a higher utilization factor and increased cost effectiveness. This paper presents new experimental data for a small-scale turbine with BT composite blades. The research team tested the turbine in the Kelvin Hydrodynamics Laboratory towing tank at the University of Strathclyde in Glasgow, United Kingdom, and in the recirculating current flume at the l Institut Francais de Recherche pour l Exploitation de la Mer Centre in Boulogne-sur-Mer, France. Tests were also performed on rigid aluminum blades with identical geometry, which yielded baseline test sets for comparison. The results from both facilities agreed closely, supporting the hypothesis that increased blade flexibility can induce load reductions. Under the most extreme conditions tested the turbine with BT blades had up to 11 percent lower peak thrust loads and a 15 percent reduction in peak power compared to the turbine with rigid blades. The load reductions varied as a function of turbine rotational velocity and ambient flow velocity.

  6. Computational investigation of flow control by means of tubercles on Darrieus wind turbine blades

    Science.gov (United States)

    Sevinç, K.; Özdamar, G.; Şentürk, U.; Özdamar, A.

    2015-09-01

    This work presents the current status of the computational study of the boundary layer control of a vertical axis wind turbine blade by modifying the blade geometry for use in wind energy conversion. The control method is a passive method which comprises the implementation of the tubercle geometry of a humpback whale flipper onto the leading edge of the blades. The baseline design is an H-type, three-bladed Darrieus turbine with a NACA 0015 cross-section. Finite-volume based software ANSYS Fluent was used in the simulations. Using the optimum control parameters for a NACA 634-021 profile given by Johari et al. (2006), turbine blades were modified. Three dimensional, unsteady, turbulent simulations for the blade were conducted to look for a possible improvement on the performance. The flow structure on the blades was investigated and flow phenomena such as separation and stall were examined to understand their impact on the overall performance. For a tip speed ratio of 2.12, good agreement was obtained in the validation of the baseline model with a relative error in time- averaged power coefficient of 1.05%. Modified turbine simulations with a less expensive but less accurate turbulence model yielded a decrease in power coefficient. Results are shown comparatively.

  7. Axial Fan Blade Vibration Assessment under Inlet Cross-Flow Conditions Using Laser Scanning Vibrometry

    Directory of Open Access Journals (Sweden)

    Till Heinemann

    2017-08-01

    Full Text Available In thermal power plants equipped with air-cooled condensers (ACCs, axial cooling fans operate under the influence of ambient flow fields. Under inlet cross-flow conditions, the resultant asymmetric flow field is known to introduce additional harmonic forces to the fan blades. This effect has previously only been studied numerically or by using blade-mounted strain gauges. For this study, laser scanning vibrometry (LSV was used to assess fan blade vibration under inlet cross-flow conditions in an adapted fan test rig inside a wind tunnel test section. Two co-rotating laser beams scanned a low-pressure axial fan, resulting in spectral, phase-resolved surface vibration patterns of the fan blades. Two distinct operating points with flow coefficients of 0.17 and 0.28 were examined, with and without inlet cross-flow influence. While almost identical fan vibration patterns were found for both reference operating points, the overall blade vibration increased by 100% at the low fan flow rate as a result of cross-flow, and by 20% at the high fan flow rate. While numerically predicted natural frequency modes could be confirmed from experimental data as minor peaks in the vibration amplitude spectrum, they were not excited significantly by cross-flow. Instead, primarily higher rotation-rate harmonics were amplified; that is, a synchronous blade-tip flapping was strongly excited at the blade-pass frequency.

  8. Cooling arrangement for a tapered turbine blade

    Science.gov (United States)

    Liang, George

    2010-07-27

    A cooling arrangement (11) for a highly tapered gas turbine blade (10). The cooling arrangement (11) includes a pair of parallel triple-pass serpentine cooling circuits (80,82) formed in an inner radial portion (50) of the blade, and a respective pair of single radial channel cooling circuits (84,86) formed in an outer radial portion (52) of the blade (10), with each single radial channel receiving the cooling fluid discharged from a respective one of the triple-pass serpentine cooling circuit. The cooling arrangement advantageously provides a higher degree of cooling to the most highly stressed radially inner portion of the blade, while providing a lower degree of cooling to the less highly stressed radially outer portion of the blade. The cooling arrangement can be implemented with known casting techniques, thereby facilitating its use on highly tapered, highly twisted Row 4 industrial gas turbine blades that could not be cooled with prior art cooling arrangements.

  9. Diagnostic methods of a bladed disc mode shape evaluation used for shrouded blades in steam turbines

    Science.gov (United States)

    Strnad, Jaromir; Liska, Jindrich

    2015-11-01

    This paper deals with advanced methods for the evaluation of a bladed disc behavior in terms of the wheel vibration and blade service time consumption. These methods are developed as parts of the noncontact vibration monitoring system of the steam turbine shrouded blades. The proposed methods utilize the time-frequency processing (cross spectra) and the method using least squares to analyse the data from the optical and magnetoresistive sensors, which are mounted in the stator radially above the rotor blades. Fundamentally, the blade vibrations are detected during the blade passages under the sensors and the following signal processing, which covers also the proposed methods, leads to the estimation of the blade residual service life. The prototype system implementing above mentioned techniques was installed into the last stage of the new steam turbine (LP part). The methods for bladed disc mode shape evaluation were successfully verified on the signals, which were obtained during the commission operation of the turbine.

  10. Finite element analysis of flexible, rotating blades

    Science.gov (United States)

    Mcgee, Oliver G.

    1987-01-01

    A reference guide that can be used when using the finite element method to approximate the static and dynamic behavior of flexible, rotating blades is given. Important parameters such as twist, sweep, camber, co-planar shell elements, centrifugal loads, and inertia properties are studied. Comparisons are made between NASTRAN elements through published benchmark tests. The main purpose is to summarize blade modeling strategies and to document capabilities and limitations (for flexible, rotating blades) of various NASTRAN elements.

  11. Nutritional content of supermarket ready meals and recipes by television chefs in the United Kingdom: cross sectional study.

    Science.gov (United States)

    Howard, Simon; Adams, Jean; White, Martin

    2012-12-14

    To compare the energy and macronutrient content of main meals created by television chefs with ready meals sold by supermarkets, and to compare both with nutritional guidelines published by the World Health Organization and UK Food Standards Agency. Cross sectional study. Three supermarkets with the largest share of the grocery market in the United Kingdom, 2010. 100 main meal recipes from five bestselling cookery books by UK television chefs and 100 own brand ready meals from the three leading UK supermarkets. Number of meals for which the nutritional content complied with WHO recommendations, and the proportion of nutrients classified as red, amber, or green using the UK FSA's "traffic light" system for labelling food. No recipe or ready meal fully complied with the WHO recommendations. The ready meals were more likely to comply with the recommended proportions of energy derived from carbohydrate (18% v 6%, P=0.01) and sugars (83% v 81%, P=0.05) and fibre density (56% v 14% Psupermarkets complied with WHO recommendations. Recipes were less healthy than ready meals, containing significantly more energy, protein, fat, and saturated fat, and less fibre per portion than the ready meals.

  12. Coping behavior and risk and resilience stress factors in French regional emergency medicine unit workers: a cross-sectional survey

    Science.gov (United States)

    Lala, AI; Sturzu, LM; Picard, JP; Druot, F; Grama, F; Bobirnac, G

    2016-01-01

    The Emergency Department (ED) has the highest workload in a hospital, offering care to patients in their most acute state of illness, as well as comforting their families and tending to stressful situations of the physical and psychological areal. Method. A cross-sectional survey of 366 Emergency Unit staff members including medical doctors, medical residents, medical nurses and ward aids, was undergone. Study participants came from four periphery hospitals in the Moselle Department of Eastern France with similar workforce and daily patient loads statistics. The instruments used were the Perceived Stress Scale PSS-10 and the Brief COPE questionnaire. Conclusions. Perceived work overload and overall stress is strongly related to work hours and tend to have a stronger influence on doctors than on the nursing staff. Substance use is a common coping method for medical interns, consistent with prior research. The regular assessment of the ED staff perception of stress and stress related factors is essential to support organizational decisions in order to promote a better work environment and better patient care. PMID:27928439

  13. Coping behavior and risk and resilience stress factors in French regional emergency medicine unit workers: a cross-sectional survey.

    Science.gov (United States)

    Lala, A I; Sturzu, L M; Picard, J P; Druot, F; Grama, F; Bobirnac, G

    2016-01-01

    The Emergency Department (ED) has the highest workload in a hospital, offering care to patients in their most acute state of illness, as well as comforting their families and tending to stressful situations of the physical and psychological areal. Method. A cross-sectional survey of 366 Emergency Unit staff members including medical doctors, medical residents, medical nurses and ward aids, was undergone. Study participants came from four periphery hospitals in the Moselle Department of Eastern France with similar workforce and daily patient loads statistics. The instruments used were the Perceived Stress Scale PSS-10 and the Brief COPE questionnaire. Conclusions. Perceived work overload and overall stress is strongly related to work hours and tend to have a stronger influence on doctors than on the nursing staff. Substance use is a common coping method for medical interns, consistent with prior research. The regular assessment of the ED staff perception of stress and stress related factors is essential to support organizational decisions in order to promote a better work environment and better patient care.

  14. Wind turbine blade testing under combined loading

    DEFF Research Database (Denmark)

    Roczek-Sieradzan, Agnieszka; Nielsen, Magda; Branner, Kim;

    2011-01-01

    The paper presents full-scale blade tests under a combined flap- and edgewise loading. The main aim of this paper is to present the results from testing a wind turbine blade under such conditions and to study the structural behavior of the blade subjected to combined loading. A loading method using...... anchor plates was applied, allowing transverse shear distortion. The global and local deformation of the blade as well as the reproducibility of the test was studied and the results from the investigations are presented....

  15. Reliability design method for steam turbine blades

    Institute of Scientific and Technical Information of China (English)

    Jinyuan SHI

    2008-01-01

    Based on theories of probability and statistics, and taking static stresses, dynamic stresses, endurance strength, safety ratios, vibration frequencies and exciting force frequencies of blades as random variables, a reliabil-ity design method for steam turbine blades is presented. The purport and calculation method for blade reliability are expounded. The distribution parameters of random variables are determined after analysis and numerical cal-culation of test data. The fatigue strength and the vibra-tion design reliability of turbine blades are determined with the aid of a probabilistic design method and by inter-ference models for stress distribution and strength distri-bution. Some blade reliability design calculation formulas for a dynamic stress design method, a safety ratio design method for fatigue strength, and a vibration reliability design method for the first and second types of tuned blades and a packet of blades on a disk connected closely, are given together with some practical examples. With these methods, the design reliability of steam turbine blades can be guaranteed in the design stage. This research may provide some scientific basis for reliability design of steam turbine blades.

  16. Modal dynamics of structures with bladed isotropic rotors and its complexity for 2-bladed rotors

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig

    2016-01-01

    wind turbine model consisting of three degrees of freedom for each blade and seven degrees of freedom for the nacelle and drivetrain. The modal dynamics of a 3-bladed 10MW turbine from previous studies is recaptured. Removing one blade, the larger and higher harmonic terms in the system matrix lead...

  17. Modal dynamics of structures with bladed isotropic rotors and its complexity for two-bladed rotors

    Directory of Open Access Journals (Sweden)

    M. H. Hansen

    2016-11-01

    These harmonic terms lead to modal couplings for the two-bladed turbine that do not exist for the three-bladed turbine. A single mode of a two-bladed turbine will also have several resonance frequencies in both the ground-fixed and rotating frames of reference, which complicates the interpretation of simulated or measured turbine responses.

  18. Structural Testing of the Blade Reliability Collaborative Effect of Defect Wind Turbine Blades

    Energy Technology Data Exchange (ETDEWEB)

    Desmond, M. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hughes, S. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Paquette, J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-06-08

    Two 8.3-meter (m) wind turbine blades intentionally constructed with manufacturing flaws were tested to failure at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) south of Boulder, Colorado. Two blades were tested; one blade was manufactured with a fiberglass spar cap and the second blade was manufactured with a carbon fiber spar cap. Test loading primarily consisted of flap fatigue loading of the blades, with one quasi-static ultimate load case applied to the carbon fiber spar cap blade. Results of the test program were intended to provide the full-scale test data needed for validation of model and coupon test results of the effect of defects in wind turbine blade composite materials. Testing was part of the Blade Reliability Collaborative (BRC) led by Sandia National Laboratories (SNL). The BRC seeks to develop a deeper understanding of the causes of unexpected blade failures (Paquette 2012), and to develop methods to enable blades to survive to their expected operational lifetime. Recent work in the BRC includes examining and characterizing flaws and defects known to exist in wind turbine blades from manufacturing processes (Riddle et al. 2011). Recent results from reliability databases show that wind turbine rotor blades continue to be a leading contributor to turbine downtime (Paquette 2012).

  19. Anisotropic beam model for analysis and design of passive controlled wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Branner, K.; Blasques, J.P.; Kim, T.; Fedorov, V.A.; Berring, P.; Bitsche, R.D.; Berggreen, C.

    2012-02-15

    The main objective of the project was, through theoretical and experimental research, to develop and validate a fully coupled, general beam element that can be used for advanced and rapid analysis of wind turbine blades. This is fully achieved in the project and the beam element has even been implemented in the aeroelastic code HAWC2. It has also been demonstrated through a parametric study in the project that a promising possibility with the tool is to reduce fatigue loads through structural couplings. More work is needed before these possibilities are fully explored and blades with structural couplings can be put into production. A cross section analysis tool BECAS (BEam Cross section Analysis Software) has been developed and validated in the project. BECAS is able to predict all geometrical and material induced couplings. This tool has obtained great interest from both industry and academia. The developed fully coupled beam element and cross section analysis tool has been validated against both numerical calculations and experimental measurements. Numerical validation has been performed against beam type calculations including Variational Asymptotical Beam Section Analysis (VABS) and detailed shell and solid finite element analyses. Experimental validation included specially designed beams with built-in couplings, a full-scale blade section originally without couplings, which subsequently was modified with extra composite layers in order to obtain measurable couplings. Both static testing and dynamic modal analysis tests have been performed. The results from the project now make it possible to use structural couplings in an intelligent manner for the design of future wind turbine blades. The developed beam element is especially developed for wind turbine blades and can be used for modeling blades with initial curvature (pre-bending), initial twist and taper. Finally, it have been studied what size of structural couplings can be obtained in current and future

  20. Study on finite deformation finite element analysis algorithm of turbine blade based on CPU+GPU heterogeneous parallel computation

    Directory of Open Access Journals (Sweden)

    Liu Tian-Yuan

    2016-01-01

    Full Text Available Blade is one of the core components of turbine machinery. The reliability of blade is directly related to the normal operation of plant unit. However, with the increase of blade length and flow rate, non-linear effects such as finite deformation must be considered in strength computation to guarantee enough accuracy. Parallel computation is adopted to improve the efficiency of classical nonlinear finite element method and shorten the blade design period. So it is of extraordinary importance for engineering practice. In this paper, the dynamic partial differential equations and the finite element method forms for turbine blades under centrifugal load and flow load are given firstly. Then, according to the characteristics of turbine blade model, the classical method is optimized based on central processing unit + graphics processing unit heterogeneous parallel computation. Finally, the numerical experiment validations are performed. The computation speed of the algorithm proposed in this paper is compared with the speed of ANSYS. For the rectangle plate model with mesh number of 10 k to 4000 k, a maximum speed-up of 4.31 can be obtained. For the real blade-rim model with mesh number of 500 k, the speed-up of 4.54 times can be obtained.

  1. Experimental Blade Research - phase 2

    OpenAIRE

    Eder, Martin Alexander; Branner, Kim; Berring, Peter; Belloni, Federico; Stensgaard Toft, Henrik; Sørensen, John Dalsgaard; Corre, Adrien; Lindby, Torben; Quispitupa, Amilcar; Petersen, Thomas Karl

    2015-01-01

    This report is a summary of the results obtained in the project: Experimental Blade Research – phase 2 (EBR2). The project was supported by the Danish Energy Authority through the 2010 Energy Technology Development and Demonstration Program (EUDP 2010-II) and has journal no. 64011-0006. The project has been running from spring 2011 to the end of 2014.Being a summary report, this report only contains a collection of the research topics and the major results. For more details, see the publicati...

  2. Robotic Hot-Blade Cutting

    DEFF Research Database (Denmark)

    Søndergaard, Asbjørn; Feringa, Jelle; Nørbjerg, Toke Bjerge

    2016-01-01

    This paper presents a novel method for cost-effective, robotic production of double curved formwork in Expanded Polystyrene (EPS) for in situ and prefabricated concrete construction. A rationalization and segmentation procedure is developed, which allows for the transliteration of double curved...... NURBS surfaces to Euler elastica surface segments, while respecting various constraints of production. An 18 axis, tri-robot system approximates double curved NURBS surfaces by means of an elastically deformed and heated blade, mounted on the flanges of two manipulators. Re-orienting or translating...

  3. Development of Self-Powered Wireless Structural Health Monitoring (SHM) for Wind Turbine Blades

    Science.gov (United States)

    Lim, Dong-Won

    Wind turbine blade failure can lead to unexpected power interruptions. Monitoring wind turbine blades is important to ensure seamless electricity delivery from power generation to consumers. Structural health monitoring (SHM) enables early recognition of structural problems so that the safety and reliability of operation can be enhanced. This dissertation focuses on the development of a wireless SHM system for wind turbine blades. The sensor is comprised of a piezoelectric energy harvester (EH) and a telemetry unit. The sensor node is mounted on the blade surface. As the blade rotates, the blade flexes, and the energy harvester captures the strain energy on the blade surface. Once sufficient electricity is captured, a pulse is sent from the sensing node to a gateway. Then, a central monitoring algorithm processes a series of pulses received from all three blades. This wireless SHM, which uses commercially available components, can be retrofitted to existing turbines. The harvested energy for sensing can be estimated in terms of two factors: the available strain energy and conversion efficiency. The available strain energy was evaluated using the FAST (Fatigue, Aerodynamics, Structures, and Turbulence) simulator. The conversion efficiency was studied analytically and experimentally. An experimental set-up was designed to mimic the expected strain frequency and amplitude for rotor blades. From a series of experiments, the efficiency of a piezoelectric EH at a typical rotor speed (0.2 Hz) was approximately 0.5%. The power requirement for sending one measurement (280 muJ) can be achieved in 10 minutes. Designing a detection algorithm is challenging due to this low sampling rate. A new sensing approach-the timing of pulses from the transmitter-was introduced. This pulse timing, which is tied to the charging time, is indicative of the structural health. The SHM system exploits the inherent triple redundancy of the three blades. The timing data of the three blades are

  4. High Performance Computing (HPC)-Enabled Computational Study on the Feasibility of using Shape Memory Alloys for Gas Turbine Blade Actuation

    Science.gov (United States)

    2016-11-01

    hotter air will expand and is therefore storing more energy. As the hot air moves through the next section, the turbine blades rotate and move blades ...Feasibility of using Shape Memory Alloys for Gas Turbine Blade Actuation by Kathryn Esham, Luis Bravo, Anindya Ghoshal, Muthuvel Murugan, and Michael...are not to be construed as an official Department of the Army position unless so designated by other authorized documents. Citation of

  5. Urban sprawl, obesity, and cancer mortality in the United States: cross-sectional analysis and methodological challenges.

    Science.gov (United States)

    Berrigan, David; Tatalovich, Zaria; Pickle, Linda W; Ewing, Reid; Ballard-Barbash, Rachel

    2014-01-06

    Urban sprawl has the potential to influence cancer mortality via direct and indirect effects on obesity, access to health services, physical activity, transportation choices and other correlates of sprawl and urbanization. This paper presents a cross-sectional analysis of associations between urban sprawl and cancer mortality in urban and suburban counties of the United States. This ecological analysis was designed to examine whether urban sprawl is associated with total and obesity-related cancer mortality and to what extent these associations differed in different regions of the US. A major focus of our analyses was to adequately account for spatial heterogeneity in mortality. Therefore, we fit a series of regression models, stratified by gender, successively testing for the presence of spatial heterogeneity. Our resulting models included county level variables related to race, smoking, obesity, access to health services, insurance status, socioeconomic position, and broad geographic region as well as a measure of urban sprawl and several interactions. Our most complex models also included random effects to account for any county-level spatial autocorrelation that remained unexplained by these variables. Total cancer mortality rates were higher in less sprawling areas and contrary to our initial hypothesis; this was also true of obesity related cancers in six of seven U.S. regions (census divisions) where there were statistically significant associations between the sprawl index and mortality. We also found significant interactions (p obesity related cancer mortality in both sexes. Thus, the association between urban sprawl and cancer mortality differs in different regions of the US. Despite higher levels of obesity in more sprawling counties in the US, mortality from obesity related cancer was not greater in such counties. Identification of disparities in cancer mortality within and between geographic regions is an ongoing public health challenge and an

  6. Effect of blade surface roughness on performance of axial flow fans with different blade cambers

    Science.gov (United States)

    Kaneko, K.; Setoguchi, T.; Nakano, T.; Inoue, M.

    1985-07-01

    Three kinds of axial fan rotor blades with different cambers were designed, and performance tests with various blade surface roughnesses were conducted. The total pressure coefficient, the fan efficiency, and the torque coefficient decrease with increasing surface roughness. The selection of the design camber has a significant influence on the deterioration of fan performance with surface roughness. For a smooth surface, a high-cambered blade indicates a more favorable performance than a low-cambered rotor blade, but such a blade is very sensitive to surface roughness and exhibits a remarkable deterioration in performance with increased roughness. For a low-cambered rotor blade, the torque coefficient changes little with increasing roughness. The empirical relation between turning angle variation of a two-dimensional cascade and surface roughness agrees well with these results only for a rotor blade designed for the optimum angle of attack.

  7. Crack Propagation in Compressor Rotor Blade

    Science.gov (United States)

    2012-08-01

    by local Public Affairs Office) 13. SUPPLEMENTARY NOTES 14. ABSTRACT Turbomachine blading crack propagation and initiations are one of...the most important problems. Design, operation and modernization of the contemporary turbomachines are impossible without a detailed numerical and...Rao, J. S., Turbine Blade Life Estimation, Narosa Publishing House, (2000). Rao, J. S., Narayan, R. and Ranjith, M. C., Lifing of Turbomachine

  8. Study of Wear of Pitched Blade Impellers

    Directory of Open Access Journals (Sweden)

    I. Fořt

    2000-01-01

    Full Text Available A study was made of the erosion of blades of pitched blade impellers in a suspension of solid particles in a liquid under a turbulent regime of flow of an agitated charge. The wear of the impeller is described by an analytical approximation in exponential form, and the influence of the pitch angle on the impeller blade wear was studied experimentally. It follows from the results of the experiments made that the wear rate of the pitched blade impellers increases linearly with the decreasing pitch angle within the interval a Î á15°; 45° ń. The proposed form of radial profile of the leading edge of the impeller blade enables us to calculate the surface of the worn blade. This quantity significantly decreases with the length of the period when the blades are affected by the solid particles, and its values calculated according to the suggested profile of the worn blade fit fairly well with the experimentally determined values. The results of the experiments performed are valid for homogeneous distribution of solid particles in an agitated suspension.

  9. Numerical analysis of turbine blade tip treatments

    Science.gov (United States)

    Gopalaswamy, Nath S.; Whitaker, Kevin W.

    1992-01-01

    Three-dimensional solutions of the Navier-Stokes equations for a turbine blade with a turning angle of 180 degrees have been computed, including blade tip treatments involving cavities. The geometry approximates a preliminary design for the GGOT (Generic Gas Oxidizer Turbine). The data presented here will be compared with experimental data to be obtained from a linear cascade using original GGOT blades. Results have been computed for a blade with 1 percent clearance, based on chord, and three different cavity sizes. All tests were conducted at a Reynolds number of 4 x 10 exp 7. The grid contains 39,440 points with 10 spanwise planes in the tip clearance region of 5.008E-04 m. Streamline plots and velocity vectors together with velocity divergence plots reveal the general flow behavior in the clearance region. Blade tip temperature calculations suggest placement of a cavity close to the upstream side of the blade tip for reduction of overall blade tip temperature. The solutions do not account for the relative motion between the endwall and the turbine blade. The solutions obtained are generally consistent with previous work done in this area,

  10. Flutter of Darrieus wind turbine blades

    Science.gov (United States)

    Ham, N. D.

    1978-01-01

    The testing of Darrieus wind turbines has indicated that under certain conditions, serious vibrations of the blades can occur, involving flatwise bending, torsion, and chordwise bending. A theoretical method of predicting the aeroelastic stability of the coupled bending and torsional motion of such blades with a view to determining the cause of these vibrations, and a means of suppressing them was developed.

  11. Method of making counterrotating aircraft propeller blades

    Science.gov (United States)

    Nelson, Joey L. (Inventor); Elston, III, Sidney B. (Inventor); Tseng, Wu-Yang (Inventor); Hemsworth, Martin C. (Inventor)

    1990-01-01

    An aircraft propeller blade is constructed by forming two shells of composite material laminates and bonding the two shells to a metallic spar with foam filler pieces interposed between the shells at desired locations. The blade is then balanced radially and chordwise.

  12. Massachusetts Large Blade Test Facility Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Rahul Yarala; Rob Priore

    2011-09-02

    Project Objective: The Massachusetts Clean Energy Center (CEC) will design, construct, and ultimately have responsibility for the operation of the Large Wind Turbine Blade Test Facility, which is an advanced blade testing facility capable of testing wind turbine blades up to at least 90 meters in length on three test stands. Background: Wind turbine blade testing is required to meet international design standards, and is a critical factor in maintaining high levels of reliability and mitigating the technical and financial risk of deploying massproduced wind turbine models. Testing is also needed to identify specific blade design issues that may contribute to reduced wind turbine reliability and performance. Testing is also required to optimize aerodynamics, structural performance, encourage new technologies and materials development making wind even more competitive. The objective of this project is to accelerate the design and construction of a large wind blade testing facility capable of testing blades with minimum queue times at a reasonable cost. This testing facility will encourage and provide the opportunity for the U.S wind industry to conduct more rigorous testing of blades to improve wind turbine reliability.

  13. Flow separation on wind turbines blades

    Science.gov (United States)

    Corten, G. P.

    2001-01-01

    In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ of energy annually. This contributes to the total electricity demand by only 0.2%. Both the installed power and the generated energy are increasing by 30% per year world-wide. If the airflow over wind turbine blades could be controlled fully, the generation efficiency and thus the energy production would increase by 9%. Power Control To avoid damage to wind turbines, they are cut out above 10 Beaufort (25 m/s) on the wind speed scale. A turbine could be designed in such a way that it converts as much power as possible in all wind speeds, but then it would have to be to heavy. The high costs of such a design would not be compensated by the extra production in high winds, since such winds are rare. Therefore turbines usually reach maximum power at a much lower wind speed: the rated wind speed, which occurs at about 6 Beaufort (12.5 m/s). Above this rated speed, the power intake is kept constant by a control mechanism. Two different mechanisms are commonly used. Active pitch control, where the blades pitch to vane if the turbine maximum is exceeded or, passive stall control, where the power control is an implicit property of the rotor. Stall Control The flow over airfoils is called "attached" when it flows over the surface from the leading edge to the trailing edge. However, when the angle of attack of the flow exceeds a certain critical angle, the flow does not reach the trailing edge, but leaves the surface at the separation line. Beyond this line the flow direction is reversed, i.e. it flows from the trailing edge backward to the separation line. A blade section extracts much less energy from the flow when it separates. This property is used for stall control. Stall controlled rotors always operate at a constant rotation speed. The angle of attack of the flow incident to the blades is determined by the blade speed and the wind speed. Since the latter is variable, it determines

  14. Multiaxial fatigue of in-service aluminium longerons for helicopter rotor-blades

    Directory of Open Access Journals (Sweden)

    A. Shanyavskiy

    2016-10-01

    Full Text Available Fatigue cracking of longerons manufactured from Al-alloy AVT-1 for helicopter in-service rotor-blades was considered and crack growth period and equivalent of tensile stress for different blade sections were estimated. Complicated case of in-service blades multiaxial cyclically bending-rotating and tension can be considered based on introduced earlier master curve constructed for aluminum alloys in the simple case of uniaxial tension with stress R-ratio near to zero. Calculated equivalent tensile stress was compared for different blade sections and it was shown that in-service blades experienced not principle difference in this value in the crack growth direction by the investigated sections. It is not above the designed equivalent stress level. Crack growth period estimation in longerons based on fatigue striation spacing or meso-beach-marks measurements has shown that monitoring system introduced designer in longerons can be effectively used for in-time crack detecting independently on the failed section when can appeared because of various type of material faults or in-service damages

  15. A Two-Bladed Concept Wind Turbine

    DEFF Research Database (Denmark)

    Kim, Taeseong

    2012-01-01

    This article shows the potential for reducing extreme loads with an innovative design of wind turbine, a partial pitch two-bladed concept turbine. The most extreme conditions to test a turbine are considered to be stand-still combined with a grid failure in which the wind comes from all directions...... from 0 to 360 degrees. All aeroelastic load simulations are done by using the aeroelastic code HAWC2. From the load comparisons between the partial pitch two-bladed turbine and a conventional three-bladed turbine it is observed that the partial pitch two-bladed turbine can reduce the extreme tower...... bottom bending moment by approximately 33% compared to the three-bladed turbine....

  16. A Two-Bladed Concept Wind Turbine

    DEFF Research Database (Denmark)

    Kim, Taeseong

    2012-01-01

    This article shows the potential for reducing extreme loads with an innovative design of wind turbine, a partial pitch two-bladed concept turbine. The most extreme conditions to test a turbine are considered to be stand-still combined with a grid failure in which the wind comes from all directions...... from 0 to 360 degrees. All aeroelastic load simulations are done by using the aeroelastic code HAWC2. From the load comparisons between the partial pitch two-bladed turbine and a conventional three-bladed turbine it is observed that the partial pitch two-bladed turbine can reduce the extreme tower...... bottom bending moment by approximately 33% compared to the three-bladed turbine....

  17. The SNL100-01 blade :

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, Daniel

    2013-02-01

    A series of design studies to investigate the effect of carbon on blade weight and performance for large blades was performed using the Sandia 100-meter All-glass Baseline Blade design as a starting point. This document provides a description of the final carbon blade design, which is termed as SNL100-01. This report includes a summary of the design modifications applied to the baseline all-glass 100-meter design and a description of the NuMAD model files that are made publicly available. This document is intended primarily to be a companion document to the distribution of the NuMAD blade model files for SNL100-01.

  18. Advanced Blade Manufacturing Project - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    POORE, ROBERT Z.

    1999-08-01

    The original scope of the project was to research improvements to the processes and materials used in the manufacture of wood-epoxy blades, conduct tests to qualify any new material or processes for use in blade design and subsequently build and test six blades using the improved processes and materials. In particular, ABM was interested in reducing blade cost and improving quality. In addition, ABM needed to find a replacement material for the mature Douglas fir used in the manufacturing process. The use of mature Douglas fir is commercially unacceptable because of its limited supply and environmental concerns associated with the use of mature timber. Unfortunately, the bankruptcy of FloWind in June 1997 and a dramatic reduction in AWT sales made it impossible for ABM to complete the full scope of work. However, sufficient research and testing were completed to identify several promising changes in the blade manufacturing process and develop a preliminary design incorporating these changes.

  19. Failure analysis of air fan blades

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-qing; JI Zhe; CUI Yong-li; CUI Chun-zhi; SUN Zhi

    2008-01-01

    The failure of all 12 blades of an air fan was investigated by metallurgical and mechanical experiments and an examina-tion of the fracture surface. The experimental results show that the cast aluminium-silicon alloy without any modification had a number of material defects, such as coarse grains, a loose structure, a large number of shrinkage holes, a long and thin bold-pin shaped silicon-phase, poor material strength and serious brittleness. In addition, installed on the spindle without elastic conjunction,blade No. 10 vibrated and inevitably.spun off due to the large centrifugal force. Therefore, blade No. 10 first cracked at the locking handle, then broke at the root, which caused all the other 11 blades to be broken by the crack of blade No.10.

  20. Modal analysis of wind turbine blades

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Hansen, M.H.; Baumgart, A.

    2002-01-01

    The modal analysis technique has been used to identify essential dynamic properties of wind turbine blades like natural frequencies, damping characteristics and mode shapes. Different experimental procedures have been considered, and the most appropriateof these has been selected. Although...... the comparison is based on measurements on a LM 19 m blade, the recommendations given are believed to be valid for other wind turbine blades as well. The reliability of the selected experimental analysis has beenquantified by estimating the unsystematic variations in the experimental findings. Satisfactory....... The experimental analysis of the LM 19 m blade has been compared with results from a state-of-the-art FE-modeling ofthe same blade. For some of the higher modes substantial discrepancies between the natural frequencies originating from the FE-modeling and the modal analysis, respectively, are observed. In general...

  1. Applied modal analysis of wind turbine blades

    DEFF Research Database (Denmark)

    Pedersen, H.B.; Kristensen, O.J.D.

    2003-01-01

    In this project modal analysis has been used to determine the natural frequencies, damping and the mode shapes for wind turbine blades. Different methods to measure the position and adjust the direction of the measuring points are discussed. Differentequipment for mounting the accelerometers...... is investigated by repeated measurement on the same wind turbine blade. Furthermore the flexibility of the test set-up is investigated, by use ofaccelerometers mounted on the flexible adapter plate during the measurement campaign. One experimental campaign investigated the results obtained from a loaded...... and unloaded wind turbine blade. During this campaign the modal analysis are performed on ablade mounted in a horizontal and a vertical position respectively. Finally the results obtained from modal analysis carried out on a wind turbine blade are compared with results obtained from the Stig Øyes blade_EV1...

  2. Wave-induced dynamics of flexible blades

    CERN Document Server

    Luhar, M

    2015-01-01

    We present an experimental and numerical study that describes the motion of flexible blades, scaled to be dynamically similar to natural aquatic vegetation, forced by wave-induced oscillatory flows. For the conditions tested, blade motion is governed primarily by two dimensionless variables: (i) the Cauchy number, $Ca$, which represents the ratio of the hydrodynamic forcing to the restoring force due to blade stiffness, and (ii) the ratio of the blade length to the wave orbital excursion, $L$. For flexible blades with $Ca \\gg 1$, the relationship between drag and velocity can be described by two different scaling laws at the large- and small-excursion limits. For large excursions ($L \\ll 1$), the flow resembles a unidirectional current and the scaling laws developed for steady-flow reconfiguration studies hold. For small excursions ($L \\gg 1$), the beam equations may be linearized and a different scaling law for drag applies. The experimental force measurements suggest that the small-excursion scaling applies...

  3. [Manufacture of diamond blades via microsystem technology].

    Science.gov (United States)

    Spraul, Christoph W; Ertl, Stephan; Strobel, Stefan; Gretzschel, Ralph; Schirmer, Enrico; Rösch, Rudolf; Lingenfelder, Christian; Lang, Gerhard K

    2003-04-01

    The application of diamond knives has steadily increased in ophthalmic surgery. However, the geometry of the blade, its thickness and the sharpness of the cutting edge are limited by the abrasive diamond polishing process, e. g. the crystalline morphology of the bulk material and the grinding powder used. A new generation of diamond blades is presented herewith allowing free choice of blade shape and thickness and possessing excellent sharpness due to a new polishing process. The new production method is based on a high-quality CVD (chemical vapour deposition) diamond film of some tenths of microns thickness, deposited on a silicon wafer as microchip technology. The mechanical properties of this synthetic diamond film are almost equal to those of a natural diamond and the surface of this film is mirror-like after deposition without requiring post-polishing. The shape of the blade can be freely defined and is transferred into the diamond film by a plasma polishing process adopted from microsystem technology. The new production method results in highly reproducible diamond blades. Concave blades and round shapes can now be realised without the restrictions of the conventional production process. The force-free fabrication method even allows realisation of miniaturized blades (e. g. width production. Plasma polishing by means of gas atoms results in extreme sharpness with the cutting edge radius in the range of approx. 3 nm. Utilising microsystem technology we were able to manufacture reproducible artificial diamond blades. The new process offers for the first time surgeons a possibility of designing blades with a geometry close to their personal needs. Furthermore, the potential of facet-free ergonomically shaped diamond blades may stimulate further improvements towards novel surgical techniques.

  4. Condition Monitoring of Blade in Turbomachinery: A Review

    Directory of Open Access Journals (Sweden)

    Ahmed M. Abdelrhman

    2014-03-01

    Full Text Available Blade faults and blade failures are ranked among the most frequent causes of failures in turbomachinery. This paper provides a review on the condition monitoring techniques and the most suitable signal analysis methods to detect and diagnose the health condition of blades in turbomachinery. In this paper, blade faults are categorised into five types in accordance with their nature and characteristics, namely, blade rubbing, blade fatigue failure, blade deformations (twisting, creeping, corrosion, and erosion, blade fouling, and loose blade. Reviews on characteristics and the specific diagnostic methods to detect each type of blade faults are also presented. This paper also aims to provide a reference in selecting the most suitable approaches to monitor the health condition of blades in turbomachinery.

  5. Crack of a first stage blade in a steam turbine

    Directory of Open Access Journals (Sweden)

    M. Nurbanasari

    2014-10-01

    Full Text Available The failure of the first stage blade in a steam turbine of 55 MW was investigated. The blade was made of 17-4 PH stainless steel and has been used for 12 years before failure. The current work aims to find out the main cause of the first stage blade failure. The methods for investigation were metallurgical analysis, chemical composition test, and hardness measurement. The result showed that there was no evidence the blade failure was due to material. The damage found on the blade namely crack on the blade root. Two locations of the crack observed at the blade root, which was at the tang and the fillet, with different failure modes. In general, the damage of the blade was started by the corrosion occurred on the blade root. The crack at the blade root tang was due to corrosion fatigue and the crack occurred at the blade root fillet owing to stress corrosion cracking.

  6. Adiabatic Effectiveness and Heat Transfer Coefficient on a Film-Cooled Rotating Blade

    Science.gov (United States)

    Garg, Vijay K.

    1997-01-01

    three-dimensional Navier-Stokes code has been used to compute the adiabatic effectiveness and heat transfer coefficient on a rotating film-cooled turbine blade. The blade chosen is the United Technologies Research Center(UTRC) rotor with five film-cooling rows containing 83 holes, including three rows on the shower head with 49 holes, covering about 86% of the blade span. The mainstream is akin to that under real engine conditions with stagnation temperature 1900 K and stagnation pressure 3 MPa. The blade speed is taken to be 5200 rpm. The adiabatic effectiveness is higher for a rotating blade as compared to that for a stationary blade. Also, the direction of coolant injection from the shower-head holes considerably affects the effectiveness and heat transfer coefficient values on both the pressure and suction surfaces. In all cases the heat transfer coefficient and adiabatic effectiveness are highly three-dimensional in the vicinity of holes but tend to become two-dimensional far downstream.

  7. Nutritional content of supermarket ready meals and recipes by television chefs in the United Kingdom: cross sectional study

    Science.gov (United States)

    Adams, Jean; White, Martin

    2012-01-01

    Objectives To compare the energy and macronutrient content of main meals created by television chefs with ready meals sold by supermarkets, and to compare both with nutritional guidelines published by the World Health Organization and UK Food Standards Agency. Design Cross sectional study. Setting Three supermarkets with the largest share of the grocery market in the United Kingdom, 2010. Samples 100 main meal recipes from five bestselling cookery books by UK television chefs and 100 own brand ready meals from the three leading UK supermarkets. Main outcome measures Number of meals for which the nutritional content complied with WHO recommendations, and the proportion of nutrients classified as red, amber, or green using the UK FSA’s “traffic light” system for labelling food. Results No recipe or ready meal fully complied with the WHO recommendations. The ready meals were more likely to comply with the recommended proportions of energy derived from carbohydrate (18% v 6%, P=0.01) and sugars (83% v 81%, P=0.05) and fibre density (56% v 14% P<0.01). The recipes were more likely to comply with the recommended sodium density (36% v 4%, P<0.01), although salt used for seasoning was not assessed. The distributions of traffic light colours under the FSA’s food labelling recommendations differed: the modal traffic light was red for the recipes (47%) and green for ready meals (42%). Overall, the recipes contained significantly more energy (2530 kJ v 2067 kJ), protein (37.5 g v 27.9 g), fat (27.1 g v 17.2 g), and saturated fat (9.2 g v 6.8 g; P<0.01 for all) and significantly less fibre (3.3 g v 6.5 g, P<0.01) per portion than the ready meals. Conclusions Neither recipes created by television chefs nor ready meals sold by three of the leading UK supermarkets complied with WHO recommendations. Recipes were less healthy than ready meals, containing significantly more energy, protein, fat, and saturated fat, and less fibre per portion than the ready meals. PMID:23247976

  8. Assessing nursing quality in paediatric intensive care units: a cross-sectional study in China.

    Science.gov (United States)

    Zhang, Yuxia; Liu, Linxia; Hu, Jing; Zhang, Yanhong; Lu, Guoping; Li, Guangyu; Zuo, Zelan; Lu, Hua; Zou, Huan; Wang, Zaihua; Huang, Quelan

    2016-05-23

    Nursing-sensitive indicators are considered effective tools for improving the quality of care in hospitals. However, these have not been used in paediatric intensive care units (PICUs) in China. To develop nursing-sensitive indicators for PICUs and to assess the quality of nursing in PICUs in China based on the nursing-sensitive indicators. Multi-centre, cross-sectional study. Structure, process and outcome indicators were developed and measured from 1 January to 31 March 2014 in seven PICUs in China. The structure indicators showed that one nurse cared for an average of 2·8 patients in a PICU, and 44% of nurses had a bachelor's degree. The process indicators revealed that hand-washing compliance varied across PICUs, whereas pain management and physical restraint have not been adequately addressed in China. The outcome indicators revealed that the incidence rates of ventilator-associated pneumonia and central-line-associated blood stream infections were 2·96 and 0·7, respectively, per 1000 device days. Patients were intubated for a total of 4392 mechanical ventilator days, and 32 patients (7·29‰) had an unplanned extubation. Nurses were moderately satisfied in their jobs (3·1 ± 0·3), and parents reported that nurses provide high quality of care. This study developed and used nursing-sensitive indicators to assess the quality of nursing in PICUs in China, which provided a reference for national and international comparisons of nursing quality in PICUs. Nursing staffing levels and education should be improved. Pain management and physical restraints should be regulated in China's PICUs. Nurse managers need to explore staff attitudes towards implementation of family-centred care. The development of a national database of nursing quality indicators can contribute to quality and safety improvement. This study developed a set of nursing-sensitive indicators, and these indicators were used to assess and improve the quality of nursing in PICUs. © 2016 British

  9. Urban sprawl, obesity, and cancer mortality in the United States: cross-sectional analysis and methodological challenges

    Science.gov (United States)

    2014-01-01

    Background Urban sprawl has the potential to influence cancer mortality via direct and indirect effects on obesity, access to health services, physical activity, transportation choices and other correlates of sprawl and urbanization. Methods This paper presents a cross-sectional analysis of associations between urban sprawl and cancer mortality in urban and suburban counties of the United States. This ecological analysis was designed to examine whether urban sprawl is associated with total and obesity-related cancer mortality and to what extent these associations differed in different regions of the US. A major focus of our analyses was to adequately account for spatial heterogeneity in mortality. Therefore, we fit a series of regression models, stratified by gender, successively testing for the presence of spatial heterogeneity. Our resulting models included county level variables related to race, smoking, obesity, access to health services, insurance status, socioeconomic position, and broad geographic region as well as a measure of urban sprawl and several interactions. Our most complex models also included random effects to account for any county-level spatial autocorrelation that remained unexplained by these variables. Results Total cancer mortality rates were higher in less sprawling areas and contrary to our initial hypothesis; this was also true of obesity related cancers in six of seven U.S. regions (census divisions) where there were statistically significant associations between the sprawl index and mortality. We also found significant interactions (p obesity related cancer mortality in both sexes. Thus, the association between urban sprawl and cancer mortality differs in different regions of the US. Conclusions Despite higher levels of obesity in more sprawling counties in the US, mortality from obesity related cancer was not greater in such counties. Identification of disparities in cancer mortality within and between geographic regions is an

  10. Mass fatality preparedness among medical examiners/coroners in the United States: a cross-sectional study.

    Science.gov (United States)

    Gershon, Robyn R M; Orr, Mark G; Zhi, Qi; Merrill, Jacqueline A; Chen, Daniel Y; Riley, Halley E M; Sherman, Martin F

    2014-12-15

    In the United States (US), Medical Examiners and Coroners (ME/Cs) have the legal authority for the management of mass fatality incidents (MFI). Yet, preparedness and operational capabilities in this sector remain largely unknown. The purpose of this study was twofold; first, to identify appropriate measures of preparedness, and second, to assess preparedness levels and factors significantly associated with preparedness. Three separate checklists were developed to measure different aspects of preparedness: MFI Plan Elements, Operational Capabilities, and Pre-existing Resource Networks. Using a cross-sectional study design, data on these and other variables of interest were collected in 2014 from a national convenience sample of ME/C using an internet-based, anonymous survey. Preparedness levels were determined and compared across Federal Regions and in relation to the number of Presidential Disaster Declarations, also by Federal Region. Bivariate logistic and multivariable models estimated the associations between organizational characteristics and relative preparedness. A large proportion (42%) of respondents reported that less than 25 additional fatalities over a 48-hour period would exceed their response capacities. The preparedness constructs measured three related, yet distinct, aspects of preparedness, with scores highly variable and generally suboptimal. Median scores for the three preparedness measures also varied across Federal Regions and as compared to the number of Presidential Declared Disasters, also by Federal Region. Capacity was especially limited for activating missing persons call centers, launching public communications, especially via social media, and identifying temporary interment sites. The provision of staff training was the only factor studied that was significantly (positively) associated (p < .05) with all three preparedness measures. Although ME/Cs ranked local partners, such as Offices of Emergency Management, first responders, and

  11. Shifting tides in the emigration patterns of Canadian physicians to the United States: a cross-sectional secondary data analysis.

    Science.gov (United States)

    Freeman, Thomas R; Petterson, Stephen; Finnegan, Sean; Bazemore, Andrew

    2016-12-01

    The relative ease of movement of physicians across the Canada/US border has led to what is sometimes referred to as a 'brain drain' and previous analysis estimated that the equivalent of two graduating classes from Canadian medical schools were leaving to practice in the US each year. Both countries fill gaps in physician supply with international medical graduates (IMGs) so the movement of Canadian trained physicians to the US has international ramifications. Medical school enrolments have been increased on both sides of the border, yet there continues to be concerns about adequacy of physician human resources. This analysis was undertaken to re-examine the issue of Canadian physician migration to the US. We conducted a cross-sectional analysis of the 2015 American Medical Association (AMA) Masterfile to identify and locate any graduates of Canadian schools of medicine (CMGs) working in the United States in direct patient care. We reviewed annual reports of the Canadian Resident Matching Service (CaRMS); the Canadian Post-MD Education Registry (CAPER); and the Canadian Collaborative Centre for Physician Resources (C3PR). Beginning in the early 1990s the number of CMGs locating in the U.S. reached an all-time high and then abruptly dropped off in 1995. CMGs are going to the US for post-graduate training in smaller numbers and, are less likely to remain than at any time since the 1970's. This four decade retrospective found considerable variation in the migration pattern of CMGs to the US. CMGs' decision to emigrate to the U.S. may be influenced by both 'push' and 'pull' factors. The relative strength of these factors changed and by 2004, more CMGs were returning from abroad than were leaving and the current outflow is negligible. This study supports the need for medical human resource planning to assume a long-term view taking into account national and international trends to avoid the rapid changes that were observed. These results are of importance to medical

  12. Prevalence of Diabetes among Migrant Women and Duration of Residence in the United Arab Emirates: A Cross Sectional Study

    Science.gov (United States)

    Shah, Syed M.; Ali, Raghib; Loney, Tom; Aziz, Faisal; ElBarazi, Iffat; Al Dhaheri, Salma; Farooqi, M. Hamed

    2017-01-01

    Background The prevalence rate of type 2 diabetes mellitus (T2DM) is one of the highest in United Arab Emirates (UAE), however data for the expatriate population is limited. This study aimed to identify the prevalence of T2DM amongst migrant women and test the hypothesis that acculturation (measured by years of residency) is associated with an increased risk of T2DM. Methods This was a cross-sectional study and we recruited a representative sample (n = 599, 75% participation rate) of migrant women aged 18 years and over in Al Ain, UAE. The American Diabetes Association criteria were used to diagnose T2DM. An adapted WHO STEPS questionnaire was used to collect socio-demographic, lifestyle and clinical data. Logistic regression analysis was performed to identify correlates of T2DM including length of UAE residence. Results The mean age of participants was 34.1 (± 9.5) years. Of the study participants, based on HbA1C levels, 18.6% (95% CI: 13.9–24.4) had prediabetes and 10.7% (95% CI: 7.2–15.6) had T2DM. Prevalence of prediabetes was 8.5% for Filipinos, 16.7% for Arabs and 30.3% for South Asians. Similarly the prevalence of T2DM was 1.7% for Filipinos, 12.2% for Arabs and 16.7% for South Asians. Significant correlates of overall T2DM (measured and known diabetes) included length of UAE residence for more than 10 years (Adjusted Odds Ratio [AOR] 2.74, 95% CI: 1.21–6.20), age ≥40 years (AOR = 3.48, 95% CI: 1.53–7.87) and South Asian nationality (AOR 2.10, 95% CI: 0.94–4.70). Conclusion Diabetes is a significant public health problem among migrant women in the UAE, particularly for South Asians. Longer length of residence in the UAE is associated with a higher prevalence of diabetes. PMID:28099445

  13. Combining Unsteady Blade Pressure Measurements and a Free-Wake Vortex Model to Investigate the Cycle-to-Cycle Variations in Wind Turbine Aerodynamic Blade Loads in Yaw

    Directory of Open Access Journals (Sweden)

    Moutaz Elgammi

    2016-06-01

    Full Text Available Prediction of the unsteady aerodynamic flow phenomenon on wind turbines is challenging and still subject to considerable uncertainty. Under yawed rotor conditions, the wind turbine blades are subjected to unsteady flow conditions as a result of the blade advancing and retreating effect and the development of a skewed vortical wake created downstream of the rotor plane. Blade surface pressure measurements conducted on the NREL Phase VI rotor in yawed conditions have shown that dynamic stall causes the wind turbine blades to experience significant cycle-to-cycle variations in aerodynamic loading. These effects were observed even though the rotor was subjected to a fixed speed and a uniform and steady wind flow. This phenomenon is not normally predicted by existing dynamic stall models integrated in wind turbine design codes. This paper couples blade pressure measurements from the NREL Phase VI rotor to a free-wake vortex model to derive the angle of attack time series at the different blade sections over multiple rotor rotations and three different yaw angles. Through the adopted approach it was possible to investigate how the rotor self-induced aerodynamic load fluctuations influence the unsteady variations in the blade angles of attack and induced velocities. The hysteresis loops for the normal and tangential load coefficients plotted against the angle of attack were plotted over multiple rotor revolutions. Although cycle-to-cycle variations in the angles of attack at the different blade radial locations and azimuth positions are found to be relatively small, the corresponding variations in the normal and tangential load coefficients may be significant. Following a statistical analysis, it was concluded that the load coefficients follow a normal distribution at the majority of blade azimuth angles and radial locations. The results of this study provide further insight on how existing engineering models for dynamic stall may be improved through

  14. Ultimate strength of a large wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Moelholt Jensen, Find

    2008-05-15

    The present PhD project contains a study of the structural static strength of wind turbine blades loaded in flap-wise direction. A combination of experimental and numerical work has been used to address the most critical failure mechanisms and to get an understanding of the complex structural behaviour of wind turbine blades. Four failure mechanisms observed during the fullscale tests and the corresponding FE-analysis are presented. Elastic mechanisms associated with failure, such as buckling, localized bending and the Brazier effect, are studied. Six different types of structural reinforcements helping to prevent undesired structural elastic mechanisms are presented. The functionality of two of the suggested structural reinforcements was demonstrated in full-scale tests and the rest trough FE-studies. The blade design under investigation consisted of an aerodynamic airfoil and a load carrying box girder. In total, five full-scale tests have been performed involving one complete blade and two shortened box girders. The second box girder was submitted to three independent tests covering different structural reinforcement alternatives. The advantages and disadvantages of testing a shortened load carrying box girder vs. an entire blade are discussed. Changes in the boundary conditions, loads and additional reinforcements, which were introduced in the box girder tests in order to avoid undesired structural elastic mechanisms, are presented. New and advanced measuring equipment was used in the fullscale tests to detect the critical failure mechanisms and to get an understanding of the complex structural behaviour. Traditionally, displacement sensors and strain gauges in blade tests are arranged based on an assumption of a Bernoulli-Euler beam structural response. In the present study it is shown that when following this procedure important information about distortions of the cross sections is lost. In the tests presented here, one of the aims was to measure distortion

  15. Influence of pitch, twist, and taper on a blade`s performance loss due to roughness

    Energy Technology Data Exchange (ETDEWEB)

    Tangler, J.L. [National Renewable Energy Laboratory, Golden, Colorado (United States)

    1997-08-01

    The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade`s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor`s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP computer code with wind-tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord, non-twisted blade at several blade pitch angles. The results indicate that a constant-chord, non-twisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness. (au)

  16. Influence of pitch, twist, and taper on a blade`s performance loss due to roughness

    Energy Technology Data Exchange (ETDEWEB)

    Tangler, J.L. [National Renewable Energy Lab., Golden, CO (United States)

    1996-12-31

    The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade`s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor`s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP computer code with wind-tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord, non-twisted blade at several blade pitch angles. The results indicate that a constant-chord, non-twisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness. 8 refs., 6 figs.

  17. Dynamic stall development in the near-root region of a model wind turbine blade

    Science.gov (United States)

    Melius, Matthew; Cal, Raul Bayoan; Mulleners, Karen

    2014-11-01

    The dynamic behavior of atmospheric flows create highly variable operational conditions which affect the life expectancy of the turbine components and the power output of the turbine. To gain insight into the unsteady aerodynamics of wind turbine blades, wind tunnel experiments were conducted with a scaled three-dimensional NREL 5MW wind turbine blade model in the 2.2 m × 1.8 m cross-section closed loop wind tunnel DLR in Göttingen. The development of dynamic stall in response to a sudden change in the blades angle of attack are studied by means of time-resolved stereoscopic PIV in span-wisely distributed planes capturing the suction side of the blade. The change in angle of attack was obtained by varying the blade pitch angle to simulate a sudden change in wind speed or pitch angle regulation. Resulting time scales associated with flow separation and reattachment are determined at different radial positions ranging from r / R = 0 . 19 to r / R = 0 . 38 . The influence of the three-dimensionality of the blade geometry on the corresponding aerodynamic effects is captured by analyzing the radial flow component in neighboring measurement fields during stall development.

  18. Structural Health Monitoring on Turbine Engines Using Microwave Blade Tip Clearance Sensors

    Science.gov (United States)

    Woike, Mark; Abdul-Aziz, Ali; Clem, Michelle

    2014-01-01

    The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA) has taken a lead role in the investigation of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. As part of this effort, microwave sensor technology has been investigated as a means of making high temperature non-contact blade tip clearance, blade tip timing, and blade vibration measurements for use in gas turbine engines. This paper presents a summary of key results and findings obtained from the evaluation of two different types of microwave sensors that have been investigated for use possible in structural health monitoring applications. The first is a microwave blade tip clearance sensor that has been evaluated on a large scale Axial Vane Fan, a subscale Turbofan, and more recently on sub-scale turbine engine like disks. The second is a novel microwave based blade vibration sensor that was also used in parallel with the microwave blade tip clearance sensors on the experiments with the sub-scale turbine engine disks.

  19. Factors contributing to deep supercooling capability and cold survival in dwarf bamboo (Sasa senanensis leaf blades.

    Directory of Open Access Journals (Sweden)

    Masaya eIshikawa

    2015-01-01

    Full Text Available Wintering Sasa senanensis, dwarf bamboo, has been known to employ deep supercooling as the mechanism of cold hardiness in its most of the tissues from leaves to rhizomes. The unique cold hardiness mechanism of this plant was further characterized using current year leaf blades. Cold hardiness levels increased from August (LT20: –11 °C to December (LT20: –20 °C, which coincided with the initiation temperature of low temperature exotherms (LTE detected in differential thermal analyses. When leaf blades were stored at –5 °C for 1-14 days, there was no nucleation of the supercooled tissue units compartmentalized by the longitudinal and transverse veins either in summer or winter. However, only summer leaves suffered significant injury after prolonged supercooling of the tissue units. This may be a novel type of low temperature-induced injury in supercooled state at subfreezing temperatures. When winter leaf blades were maintained at the threshold temperature (-20 °C, a longer storage period (1-7 days increased lethal freezing of the supercooled tissue units. Within a wintering shoot, the second or third leaf blade from the top was most cold hardy and leaf blades at lower positions tended to suffer more injury due to lethal freezing of the supercooled units, which was not correlated with the leaf water content. LTE were shifted to higher temperatures (2-5 °C after a lethal freeze-thaw cycle. The results demonstrate that the tissue unit compartmentalized with longitudinal and transverse veins serves as the unit of supercooling and temperature- and time-dependent freezing of the units is lethal both in laboratory freeze tests and in the field. To establish such supercooling in the unit, structural ice barriers such as development of sclerenchyma and biochemical mechanisms to increase the stability of supercooling are considered important. We discussed these mechanisms in regard to ecological and physiological significance in winter survival.

  20. Turbomachine blading with splitter blades designed by solving the inverse flow field problem

    Science.gov (United States)

    Luu, T. S.; Viney, B.; Bencherif, L.

    1992-04-01

    The paper presents an inverse method for the turbomachine blading design in incompressible non viscous flow in order to avoid cavitation and gives a new approach of the boundary conditions to be settled in relation with bound vorticity distribution on the blades. Treating first the 2D cascade design, it shows how the blade must be generated with the given thickness distribution and must be loaded in order to obtain the desired outlet flow angle. The 3D design is analysed by two steps S2-S1 approach proposed by Wu[1]. For the meridian flow (S2 approach), the blade thickness is taken into account by the modification of metric tensor in the continuity equation. The governing one is provided by the hub to shroud equilibrium condition and the meridian stream function is choosen to define the flow field. This step leads to the determination of axisymmetrical stream sheets as well as the approximate camber surface of the blades. In the second step, blade to blade flow (S1 approach) is analyzed. The governing equation is deduced from the momentum equation which implies that the vorticity of the absolute velocity must be tangential to the stream sheet. The bound vorticity distribution must be the same one as in S2 approach and the residual flux crossing over the blade be conservative (transpiration model). These two relations constitute the boundary conditions for the S1 flow. The detection of this residual flux due to the normal component of the relative velocity on the blade surface leads to the rectification of the camber surface. The optimized design of the blading of a centifugal impeller with splitter blades is presented. Pour définir la géométrie des aubages, les méthodes conventionnelles prennent la distribution de vitesse sur les deux faces de l'aube comme données initiales. En appliquant cette approche, on perd le contrôle de l'épaisseur de l'aube. Pour y remédier, la présente méthode suggère une méthode inverse en représentant les aubes par une

  1. Quick Method for Aeroelastic and Finite Element Modeling of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Bennett, Jeffrey; Bitsche, Robert; Branner, Kim;

    2014-01-01

    -sectional analysis tool in order to obtain cross-sectional properties for the aeroelastic simulations. The method utilizes detailed user inputs of the structural layup and aerodynamic profile including ply thickness, orientation, material properties and airfoils to create the models. After the process is complete...... the user has two models of the same blade, one for performing a structural finite element model analysis and one for aeroelastic simulations. Here, the method is implemented and applied to reverse engineer a structural layup for the NREL 5MW reference blade. The model is verified by comparing natural...

  2. The general theory of blade screws including propellers, fans, helicopter screws, helicoidal pumps, turbo-motors, and different kinds of helicoidal blades

    Science.gov (United States)

    De Bothezat, George

    1920-01-01

    Report presents a theory which gives a complete picture and an exact quantitative analysis of the whole phenomenon of the working of blade screws, but also unites in a continuous whole the entire scale of states of work conceivable for a blade screw. Chapter 1 is devoted to the establishment of the system of fundamental equations relating to the blade screw. Chapter 2 contains the general discussion of the 16 states of work which may establish themselves for a blade screw. The existence of the vortex ring state and the whirling phenomenon are established. All the fundamental functions which enter the blade-screw theory are submitted to a general analytical discussion. The general outline of the curve of the specific function is examined. Two limited cases of the work of the screw, the screw with a zero constructive pitch and the screw with an infinite constructive pitch, are pointed out. Chapter 3 is devoted to the study of the propulsive screw or propeller. (author)

  3. The SNL100-02 blade :

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, Daniel

    2013-11-01

    A series of design studies are performed to investigate the effects of advanced core materials and a new core material strategy on blade weight and performance for large blades using the Sandia 100-meter blade designs as a starting point. The initial core material design studies were based on the SNL100-01 100- meter carbon spar design. Advanced core material with improved performance to weight was investigated with the goal to reduce core material content in the design and reduce blade weight. A secondary element of the core study was to evaluate the suitability of core materials from natural, regrowable sources such as balsa and recyclable foam materials. The new core strategy for the SNL100-02 design resulted in a design mass of 59 tons, which is a 20% reduction from the most recent SNL100-01 carbon spar design and over 48% reduction from the initial SNL100-00 all-glass baseline blade. This document provides a description of the final SNL100-02 design, includes a description of the major design modifications, and summarizes the pertinent blade design information. This document is also intended to be a companion document to the distribution of the NuMAD blade model files for SNL100-02 that are made publicly available.

  4. Blade Deterioration in a Gas Turbine Engine

    Directory of Open Access Journals (Sweden)

    W. Tabakoff

    1998-01-01

    Full Text Available A study has been conducted to predict blade erosion of gas turbine engines. The blade material erosion model is based on three dimensional particle trajectory simulation in the three-dimensional turbine flow field. The trajectories provide the special distribution of the particle impact parameters over the blade surface. A semi-empirical erosion model, derived from erosion tests of material samples at different particulate flow conditions, is used in the prediction of blade surface erosion based on the trajectory impact data. To improve the blade erosion resistance and to decrease the blade deterioration, the blades must be coated. For this purpose, an experimental study was conducted to investigate the behavior of rhodium platinum aluminide coating exposed to erosion by fly ash particles. New protective coatings are developed for erosion and thermal barrier. Chemical vapor deposition technique (CVD was used to apply the ceramic TiC coatings on INCO 718 and stainless steel 410. The erosive wear of the coated samples was investigated experimentally by exposing them to particle laden flow at velocities from 180 to 305m/s and temperatures from ambient to 538°C in a specially designed erosion wind tunnel. Both materials (INCO 718 and stainless steel 410 coated with CVD TiC showed one order of magnitude less erosion rate compared to some commercial coatings on the same substrates.

  5. Structural optimization study of composite wind turbine blade

    DEFF Research Database (Denmark)

    Chen, Jin; Shen, Wen Zhong; Wang, Quan;

    2013-01-01

    In this paper the initial layout of a 2. MW composite wind turbine blade is designed first. The new airfoils families are selected to design a 2. MW wind turbine blade. The finite element parametric model for the blade is established. Based on the modified Blade Element Momentum theory, a new one...

  6. Rotor blade online monitoring and fault diagnosis technology research

    DEFF Research Database (Denmark)

    Tesauro, Angelo; Pavese, Christian; Branner, Kim

    Rotor blade online monitoring and fault diagnosis technology is an important way to find blade failure mechanisms and thereby improve the blade design. Condition monitoring of rotor blades is necessary in order to ensure the safe operation of the wind turbine, make the maintenance more economical...

  7. Wind turbine blade with viscoelastic damping

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Ryan A.; Mullings, Justin L.

    2017-01-10

    A wind turbine blade (60) damped by viscoelastic material (54, 54A-F) sandwiched between stiffer load-bearing sublayers (52A, 52B, 56A, 56B) in portions of the blade effective to damp oscillations (38) of the blade. The viscoelastic material may be located in one or more of: a forward portion (54A) of the shell, an aft portion (54D) of the shell, pressure and suction side end caps (54B) of an internal spar, internal webbing walls (54C, 54E), and a trailing edge core (54F).

  8. Rotating blade vibration analysis using shells

    Science.gov (United States)

    Leissa, A. W.; Lee, J. K.; Wang, A. J.

    1981-01-01

    Shallow shell theory and the Ritz method are employed to determine the frequencies and mode shapes of turbomachinery blades having both camber and twist, rotating with non-zero angles of attack. Frequencies obtained for different degrees of shallowness and thickness are compared with results available in the literature, obtained from finite element analyses of nonrotating blades. Frequencies are also determined for a rotating blade, showing the effects of changing the (1) angular velocity of rotation, (2) disk radius and (3) angle of attack, as well as the significance of the most important body force terms.

  9. A razor blade in the gastrointestinal system

    Directory of Open Access Journals (Sweden)

    Ertuğrul Altınbilek

    2015-09-01

    Full Text Available Swallowing of a foreign object is the second most common endoscopic emergency after gastrointestinal bleeding. We aimed to report a case of razor blade swallowing that presented with abdominal pain. A 33-year-old man was brought to the emergency department by his relatives with the complaint of abdominal pain that had started after swallowing a razor blade 1 day earlier. His past history was notable for schizoaffective disorder. A plain abdominal radiogram showed multiple appearances consistent with metallic, shiny foreign objects (razor blade at multiple levels. J Clin Exp Invest 2015; 6 (3: 309-311

  10. Resonant vibration control of wind turbine blades

    DEFF Research Database (Denmark)

    Svendsen, Martin Nymann; Krenk, Steen; Høgsberg, Jan Becker

    2010-01-01

    The paper deals with introduction of damping to specific vibration modes of wind turbine blades, using a resonant controller with acceleration feedback. The wind turbine blade is represented by three-dimensional, two-node finite elements in a local, rotating frame of reference. The element....... The efficiency of the resonant controller is demonstrated for a representative turbine blade exposed to turbulent wind loading. It is found that the present explicit tuning procedure yields close to optimal tuning, with very limited modal spill-over and effective reduction of the vibration amplitudes....

  11. Predicted electrothermal deicing of aircraft blades

    Science.gov (United States)

    Keith, T. G., Jr.; Masiulaniec, K. C.; Dewitt, K. J.; Chao, D. F.

    1984-01-01

    A finite difference method is presented for the transient two-dimensional simulation of an electrothermal de-icer pad of an aircraft wing or blade. The irregular geometry of the composite ice laden blade is handled by use of a body fitted coordinate transformation. By this approach the various blade layers are mapped into a set of stacked rectangular strips in which the numerical solution takes place. Several heat conduction examples are presented in order to demonstrate the accuracy of the numerical procedure. Ice melting time predictions are made and compared to earlier predictions where possible. Finally, a new graphical presentation of thermal results is shown.

  12. Structural Analysis of Basalt Fiber Reinforced Plastic Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Mengal Ali Nawaz

    2014-07-01

    Full Text Available In this study, Basalt fiber reinforced plastic (BFRP wind turbine blade was analyzed and compared with Glass fiber reinforced plastic blade (GFRP. Finite element analysis (FEA of blade was carried out using ANSYS. Data for FEA was obtained by using rule of mixture. The shell element in ANSYS was used to simulate the wind turbine blade and to conduct its strength analysis. The structural analysis and comparison of blade deformations proved that BFRP wind turbine blade has better strength compared to GFRP wind turbine blade.

  13. 石叶概念探讨%A Discussion of How Blades are Defined

    Institute of Scientific and Technical Information of China (English)

    李锋

    2012-01-01

    technology to the Upper Paleolithic, but recognizes the importance of understanding blade technology throughout China at different times and different regions.Standard definitions distinguish blades from simple flakes by employing dimension as a significant criterion, especially the ratio of length and width. My research re-examines these definitions in a way of "genus and differentia" and presents a new definition emphasizing technological attributes as well as characteristics of the dorsal ridge. A blade is long and relatively thin and is defined as at least twice as long as it is wide (usually more than 12 mm). It is usually flaked from prepared cores with vertical ridges, and characterized by parallel sides at proximal and middle sections with straight ridges on the dorsal surface. However, there is much variability in blade production and it is hard to observe these technological features, so it is important to consider the full scope of blade manufacturing techniques in an assemblage, especially core reduction.

  14. Hospital and unit characteristics associated with nursing turnover include skill mix but not staffing level: an observational cross-sectional study.

    Science.gov (United States)

    Staggs, Vincent S; Dunton, Nancy

    2012-09-01

    Nursing turnover is expensive and may have adverse effects on patient care. Little is known about turnover's association with most hospital and nursing unit characteristics, including nurse staffing level and registered nurse skill mix. To explore associations between nursing unit turnover rates and several hospital- and unit-level variables, including staffing level and skill mix. Observational cross-sectional study of longitudinal data. 1884 nursing units in 306 U.S. acute care hospitals. During a 2-year period units reported monthly data on staffing and turnover. Total nursing staff turnover and registered nurse turnover rates were modeled as dependent variables in hierarchical Poisson regression models. The following hospital characteristics were considered as predictors: Magnet(®) status, ownership (government or non-government), teaching status, locale (metropolitan, micropolitan, or rural), and size (average daily census). The U.S. state in which the hospital was located was included as a covariate. Unit-level variables included total nursing hours per patient day, size of nursing staff, registered nurse skill mix, population age group (neonatal, pediatric, or adult), and service line (critical care, step-down, medical, surgical, medical/surgical, psychiatric, or rehabilitation). Government ownership, Magnet designation, and higher skill mix were associated with lower total turnover and registered nurse turnover. Neonatal units had lower total and registered nurse turnover than pediatric units, which had lower total and registered nurse turnover than adult units. Unit service line was associated only with total turnover. Psychiatric, critical care, and rehabilitation units had the lowest mean turnover rates, but most differences between service lines were not significant. The other explanatory variables considered were not significant. Several hospital and unit characteristic variables have significant associations with nursing turnover; these associations

  15. Multidisciplinary Optimization of Tilt Rotor Blades Using Comprehensive Composite Modeling Technique

    Science.gov (United States)

    Chattopadhyay, Aditi; McCarthy, Thomas R.; Rajadas, John N.

    1997-01-01

    An optimization procedure is developed for addressing the design of composite tilt rotor blades. A comprehensive technique, based on a higher-order laminate theory, is developed for the analysis of the thick composite load-carrying sections, modeled as box beams, in the blade. The theory, which is based on a refined displacement field, is a three-dimensional model which approximates the elasticity solution so that the beam cross-sectional properties are not reduced to one-dimensional beam parameters. Both inplane and out-of-plane warping are included automatically in the formulation. The model can accurately capture the transverse shear stresses through the thickness of each wall while satisfying stress free boundary conditions on the inner and outer surfaces of the beam. The aerodynamic loads on the blade are calculated using the classical blade element momentum theory. Analytical expressions for the lift and drag are obtained based on the blade planform with corrections for the high lift capability of rotor blades. The aerodynamic analysis is coupled with the structural model to formulate the complete coupled equations of motion for aeroelastic analyses. Finally, a multidisciplinary optimization procedure is developed to improve the aerodynamic, structural and aeroelastic performance of the tilt rotor aircraft. The objective functions include the figure of merit in hover and the high speed cruise propulsive efficiency. Structural, aerodynamic and aeroelastic stability criteria are imposed as constraints on the problem. The Kreisselmeier-Steinhauser function is used to formulate the multiobjective function problem. The search direction is determined by the Broyden-Fletcher-Goldfarb-Shanno algorithm. The optimum results are compared with the baseline values and show significant improvements in the overall performance of the tilt rotor blade.

  16. Blade system design studies volume II : preliminary blade designs and recommended test matrix.

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Dayton A. (Global Energy Concepts, LLC, Kirkland, WA)

    2004-06-01

    As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts, LLC is performing a Blade System Design Study (BSDS) concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The BSDS Volume I project report addresses issues and constraints identified to scaling conventional blade designs to the megawatt size range, and evaluated candidate materials, manufacturing and design innovations for overcoming and improving large blade economics. The current report (Volume II), presents additional discussion of materials and manufacturing issues for large blades, including a summary of current trends in commercial blade manufacturing. Specifications are then developed to guide the preliminary design of MW-scale blades. Using preliminary design calculations for a 3.0 MW blade, parametric analyses are performed to quantify the potential benefits in stiffness and decreased gravity loading by replacement of a baseline fiberglass spar with carbon-fiberglass hybrid material. Complete preliminary designs are then presented for 3.0 MW and 5.0 MW blades that incorporate fiberglass-to-carbon transitions at mid-span. Based on analysis of these designs, technical issues are identified and discussed. Finally, recommendations are made for composites testing under Part I1 of the BSDS, and the initial planned test matrix for that program is presented.

  17. Active Blade Pitch Control for Straight Bladed Darrieus Vertical Axis Wind Turbine of New Design

    DEFF Research Database (Denmark)

    Chougule, Prasad; Nielsen, Søren R.K.; Basu, Biswajit

    2013-01-01

    at low rotational speed producing very less noise during operation, although these are less efficient than Horizontal Axis Wind Turbines (HAWT). The efficiency of a VAWT has been significantly improved by H-Darrieus VAWT design based on double airfoil technology as demonstrated by the authors...... in a previous publication. Further, it is well know that the variation of the blade pitch angle during the rotation improves the power efficiency. A blade pitch variation is implemented by active blade pitch control, which operates as per wind speed and position of the blade with respect to the rotor. A double...

  18. Development of fluorine-coated wiper blade; Fusso coating blade no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Awano, Y.; Imamura, S.; Yokoo, K. [Nippon Wiper Blade Co. Ltd., Saitama (Japan); Satoji, F.; Umemoto, N.

    1998-05-01

    Recently many car drivers have used water repellency for windshields to improve a field of view, however, it causes troublesome stick-slip motion of wiper blades. Stick-slip motion increases with frictional load acting on rubber of wiper blades, and fluctuation of frictional load. To prevent such a motion, antifriction materials such as molybdenum and graphite are, in some cases, coated on rubber of wiper blades to reduce frictional load, however, the life of antifriction materials is short because of abrasion of antifriction materials, and such materials also deteriorates the wiping performance of wiper blades. The high-performance long-life wiper blade was thus developed which generates no stick-slip motion for glass coated or uncoated with water repellency by coating a specific fluororesin on rubber of wiper blades. This blade naturally guarantees higher performance and longer wiper blade life than those of conventional blades for not only glass coated with water repellency but also glass uncoated with water repellency. 2 refs., 9 figs.

  19. Doctor Blade-Coated Polymer Solar Cells

    KAUST Repository

    Cho, Nam Chul

    2016-10-25

    In this work, we report polymer solar cells based on blade-coated P3HT:PC71BM and PBDTTT-EFT:PC71BM bulk heterojunction photoactive layers. Enhanced power conversion efficiency of 2.75 (conventional structure) and 3.03% (inverted structure) with improved reproducibility was obtained from blade-coated P3HT:PC71BM solar cells, compared to spin-coated ones. Furthermore, by demonstrating 3.10% efficiency flexible solar cells using blade-coated PBDTTT-EFT:PC71BM films on the plastic substrates, we suggest the potential applicability of blade coating technique to the high throughput roll-to-roll fabrication systems.

  20. Shape Optimization of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Wang, Xudong; Shen, Wen Zhong; Zhu, Wei Jun

    2009-01-01

    This paper presents a design tool for optimizing wind turbine blades. The design model is based on an aerodynamic/aero-elastic code that includes the structural dynamics of the blades and the Blade Element Momentum (BEM) theory. To model the main aero-elastic behaviour of a real wind turbine...... of the rotor. The design variables used in the current study are the blade shape parameters, including chord, twist and relative thickness. To validate the implementation of the aerodynamic/aero-elastic model, the computed aerodynamic results are compared to experimental data for the experimental rotor used...... in the European Commision-sponsored project Model Experiments in Controlled Conditions, (MEXICO) and the computed aero-elastic results are examined against the FLEX code for flow post the Tjereborg 2 MW rotor. To illustrate the optimization technique, three wind turbine rotors of different sizes (the MEXICO 25 k...

  1. Structural analysis considerations for wind turbine blades

    Science.gov (United States)

    Spera, D. A.

    1979-01-01

    Approaches to the structural analysis of wind turbine blade designs are reviewed. Specifications and materials data are discussed along with the analysis of vibrations, loads, stresses, and failure modes.

  2. Wireless Sensors for Wind Turbine Blades Monitoring

    Science.gov (United States)

    Iftimie, N.; Steigmann, R.; Danila, N. A.; Rosu, D.; Barsanescu, P. D.; Savin, A.

    2017-06-01

    The most common defects in turbine blades may be faulty microscopic and mesoscopic appeared in matrix, no detected by classical nondestructive testing (i.e. using phased array sensors), broken fibers can also appear and develop under moderated loads, or cracks and delaminations due to low energy impacts, etc. The paper propose to present the results obtained from testing of glass fiber reinforced plastic used in the construction of the wind turbine blades as well as the monitoring of the entire scalable blade using wireless sensors placed on critical location on blade. In order to monitories the strain/stress during the tests, the determination of the location and the nature of defects have been simulated using FEM.

  3. Data Management Techniques for Blade Vibration Analysis

    Directory of Open Access Journals (Sweden)

    Przysowa Radosław

    2016-07-01

    Full Text Available Well-designed procedures are required to handle large amounts of data, generated by complex measurement systems used in engine tests. The paper presents selected methodologies and software tools for characterisation and monitoring of blade vibration. Common file formats and data structures as well as methods to process and visualise tip-timing data are discussed. Report Generation Framework (RGF developed in Python is demonstrated as a flexible tool for processing and publishing blade vibration results.

  4. FEM Analysis of Turgo Impulse Turbine Blade

    Directory of Open Access Journals (Sweden)

    Sourabh KHURANA

    2013-07-01

    Full Text Available The present research work describes the development of Turgo turbine blades on the Solidworks software. Finite element simulation (Ansys V14 has been used for analysis of stress and total deformation produced inside the Turgo impulse turbine. Finite element simulation is effective when it is used to analyze the strain and stress distribution. It has been observed during analysis that the maximum stress occurs at the root of blade suction side.

  5. Failure analysis of jet engine turbine blade

    OpenAIRE

    MILAN T. JOVANOVIĆ; Vesna Maksimović; Ivana Cvijović-Alagić

    2016-01-01

    Jet engine turbine blade cast by investment precision casting of Ni-base superalloy, which failed during exploatation, was the subject of investigation. Failure analysis was executed applying optical microscopy (OM), transmission electron microscopy (TEM) using replica technique, scaning electron microscopy (SEM) and stress rupture life tests. On the ground of obtained results it was concluded that the failure occurred as a result of structural changes caused by turbine blade overheating abov...

  6. Failure analysis of jet engine turbine blade

    Directory of Open Access Journals (Sweden)

    Milan T. Jovanović

    2016-03-01

    Full Text Available Jet engine turbine blade cast by investment precision casting of Ni-base superalloy, which failed during exploatation, was the subject of investigation. Failure analysis was executed applying optical microscopy (OM, transmission electron microscopy (TEM using replica technique, scaning electron microscopy (SEM and stress rupture life tests. On the ground of obtained results it was concluded that the failure occurred as a result of structural changes caused by turbine blade overheating above the exploitation temperature.

  7. Cardiotocography interpretation skills and the association with size of maternity unit, years of obstetric work experience and healthcare professional background: a national cross-sectional study.

    Science.gov (United States)

    Thellesen, Line; Sorensen, Jette L; Hedegaard, Morten; Rosthoej, Susanne; Colov, Nina P; Andersen, Kristine S; Bergholt, Thomas

    2017-09-01

    We aimed to examine whether cardiotocography (CTG) knowledge, interpretation skills and decision-making measured by a written assessment were associated with size of maternity unit, years of obstetric work experience and healthcare professional background. A national cross-sectional study in the setting of a CTG teaching intervention involving all 24 maternity units in Denmark. Participants were midwives (n = 1260) and specialists (n = 269) and residents (n = 142) in obstetrics and gynecology who attended a 1-day CTG course and answered a 30-item multiple-choice question test. Associations between mean test score and work conditions were analyzed using multivariable robust regression, in which the three variables were mutually adjusted. Participants from units with > 3000 deliveries/year scored higher on the test than participants from units with 4000 deliveries/year: mean difference 0.5, p = 0.006). Participants with 15 years of experience (15-20 years of experience: mean difference - 0.6, p = 0.007; > 20 years experience: mean difference - 0.9, p skills and decision-making measured by a written assessment were positively associated with working in large maternity units and having skills in small units and among experienced staff but could also reflect different levels of motivation, test familiarity and learning culture. Whether the findings are transferable to the clinical setting was not examined. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.

  8. High efficiency turbine blade coatings.

    Energy Technology Data Exchange (ETDEWEB)

    Youchison, Dennis L.; Gallis, Michail A.

    2014-06-01

    The development of advanced thermal barrier coatings (TBCs) of yttria stabilized zirconia (YSZ) that exhibit lower thermal conductivity through better control of electron beam - physical vapor deposition (EB-PVD) processing is of prime interest to both the aerospace and power industries. This report summarizes the work performed under a two-year Lab-Directed Research and Development (LDRD) project (38664) to produce lower thermal conductivity, graded-layer thermal barrier coatings for turbine blades in an effort to increase the efficiency of high temperature gas turbines. This project was sponsored by the Nuclear Fuel Cycle Investment Area. Therefore, particular importance was given to the processing of the large blades required for industrial gas turbines proposed for use in the Brayton cycle of nuclear plants powered by high temperature gas-cooled reactors (HTGRs). During this modest (~1 full-time equivalent (FTE)) project, the processing technology was developed to create graded TBCs by coupling ion beam-assisted deposition (IBAD) with substrate pivoting in the alumina-YSZ system. The Electron Beam - 1200 kW (EB-1200) PVD system was used to deposit a variety of TBC coatings with micron layered microstructures and reduced thermal conductivity below 1.5 W/m.K. The use of IBAD produced fully stoichiometric coatings at a reduced substrate temperature of 600 oC and a reduced oxygen background pressure of 0.1 Pa. IBAD was also used to successfully demonstrate the transitioning of amorphous PVD-deposited alumina to the -phase alumina required as an oxygen diffusion barrier and for good adhesion to the substrate Ni2Al3 bondcoat. This process replaces the time consuming thermally grown oxide formation required before the YSZ deposition. In addition to the process technology, Direct Simulation Monte Carlo plume modeling and spectroscopic characterization of the PVD plumes were performed. The project consisted of five tasks. These included the production of layered

  9. High efficiency turbine blade coatings

    Energy Technology Data Exchange (ETDEWEB)

    Youchison, Dennis L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gallis, Michail A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-06-01

    The development of advanced thermal barrier coatings (TBCs) of yttria stabilized zirconia (YSZ) that exhibit lower thermal conductivity through better control of electron beam - physical vapor deposition (EB-PVD) processing is of prime interest to both the aerospace and power industries. This report summarizes the work performed under a two-year Lab-Directed Research and Development (LDRD) project (38664) to produce lower thermal conductivity, graded-layer thermal barrier coatings for turbine blades in an effort to increase the efficiency of high temperature gas turbines. This project was sponsored by the Nuclear Fuel Cycle Investment Area. Therefore, particular importance was given to the processing of the large blades required for industrial gas turbines proposed for use in the Brayton cycle of nuclear plants powered by high temperature gas-cooled reactors (HTGRs). During this modest (~1 full-time equivalent (FTE)) project, the processing technology was developed to create graded TBCs by coupling ion beam-assisted deposition (IBAD) with substrate pivoting in the alumina-YSZ system. The Electron Beam - 1200 kW (EB-1200) PVD system was used to deposit a variety of TBC coatings with micron layered microstructures and reduced thermal conductivity below 1.5 W/m.K. The use of IBAD produced fully stoichiometric coatings at a reduced substrate temperature of 600°C and a reduced oxygen background pressure of 0.1 Pa. IBAD was also used to successfully demonstrate the transitioning of amorphous PVD-deposited alumina to the -phase alumina required as an oxygen diffusion barrier and for good adhesion to the substrate Ni2Al3 bondcoat. This process replaces the time consuming thermally grown oxide formation required before the YSZ deposition. In addition to the process technology, Direct Simulation Monte Carlo plume modeling and spectroscopic characterization of the PVD plumes were performed. The project consisted of five tasks. These included the

  10. Load alleviation on wind turbine blades using variable geometry

    DEFF Research Database (Denmark)

    Basualdo, Santiago

    2005-01-01

    airfoil geometry is an effective means of reducing the vibration magnitudes of an airfoil that represents a section of a wind turbine blade, when subject to stochastic wind signals. The results of this investigation encourage further investigations with 3D aeroelastic models to predict the reduction......) wind turbines, which mainly operate under this flow condition. The results show evident reductions in the airfoil displacements by using simple control strategies having the airfoil position and its first and second derivatives as input, especially at the system's eigenfrequency. The use of variable...... in loads in real wind turbines. Keywords: Variable Geometry, Wind Turbine, Load Alleviation, Fatigue Load, Trailing Edge Flap....

  11. The environmental impact of wind turbine blades

    Science.gov (United States)

    Liu, P.; Barlow, C. Y.

    2016-07-01

    The first generation of wind turbine (WT) blades are now reaching their end of life, signalling the beginning of a large problem for the future. Currently most waste is sent to landfill, which is not an environmentally desirable solution. Awareness of this issue is rising, but no studies have fully assessed the eco impact of WT blades. The present study aims to provide a macroscopic quantitative assessment of the lifetime environmental impact of WT blades. The first stage has been to analyse global data to calculate the amount of WT blade materials consumed in the past. The life cycle environmental impact of a single WT blade has then been estimated using eco data for raw materials, manufacturing processes, transportation, and operation and maintenance processes. For a typical 45.2 meter 1.5 MW blade this is 795 GJ (CO2 footprint 42.1 tonnes), dominated by manufacturing processes and raw materials (96% of the total. Based on the 2014 installed capacity, the total mass of WTB is 78 kt, their energy consumption is 82 TJ and the carbon dioxide footprint is 4.35 Mt. These figures will provide a basis for suggesting possible solutions to reduce WTB environmental impact.

  12. Sandwich materials for wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Thybo Thomsen, O. [Aalborg Univ., Dept. of Mechanical Engineering, Aalborg (Denmark)

    2006-07-01

    Wind turbine blades are being manufactured using polymer matrix composite materials (PMC), in a combination of monolithic (single skin) and sandwich composites. Present day designs are mainly based on glass fibre reinforced composites (GFRP), but for very large blades carbon fibre reinforced composites (CFRP) are being used increasingly, in addition to GFRP by several manufacturers to reduce the weight. The size of wind turbines have increased significantly over the last 25 years, and this trend is expected to continue in the future. Thus, it is anticipated that wind turbines with a rated power output in the range of 8-10 MW and a rotor diameter about 170-180 m will be developed and installed within the next 10-15 years. The paper presents an overview of current day design principles and materials technology applied for wind turbine blades, and it highlights the limitations and important design issues to be addressed for up-scaling of wind turbine blades from the current maximum length in excess of 61 m to blade lengths in the vicinity of 90 m as envisaged for future very large wind turbines. In particular, the paper discusses the potential advantages and challenges of applying sandwich type construction to a larger extent than is currently being practiced for the load carrying parts of wind turbine blades. (au)

  13. Recent Development in Turbine Blade Film Cooling

    Directory of Open Access Journals (Sweden)

    Je-Chin Han

    2001-01-01

    Full Text Available Gas turbines are extensively used for aircraft propulsion, land-based power generation, and industrial applications. Thermal efficiency and power output of gas turbines increase with increasing turbine rotor inlet temperature (RIT. The current RIT level in advanced gas turbines is far above the .melting point of the blade material. Therefore, along with high temperature material development, a sophisticated cooling scheme must be developed for continuous safe operation of gas turbines with high performance. Gas turbine blades are cooled internally and externally. This paper focuses on external blade cooling or so-called film cooling. In film cooling, relatively cool air is injected from the inside of the blade to the outside surface which forms a protective layer between the blade surface and hot gas streams. Performance of film cooling primarily depends on the coolant to mainstream pressure ratio, temperature ratio, and film hole location and geometry under representative engine flow conditions. In the past number of years there has been considerable progress in turbine film cooling research and this paper is limited to review a few selected publications to reflect recent development in turbine blade film cooling.

  14. Assessment and management of pain in newborns hospitalized in a Neonatal Intensive Care Unit: a cross-sectional study.

    Science.gov (United States)

    Sposito, Natália Pinheiro Braga; Rossato, Lisabelle Mariano; Bueno, Mariana; Kimura, Amélia Fumiko; Costa, Taine; Guedes, Danila Maria Batista

    2017-09-12

    to determine the frequency of pain, to verify the measures adopted for pain relief during the first seven days of hospitalization in the Neonatal Intensive Care Unit and to identify the type and frequency of invasive procedures to which newborns are submitted. cross-sectional retrospective study. Out of the 188 hospitalizations occurred during the 12-month period, 171 were included in the study. The data were collected from the charts and the presence of pain was analyzed based on the Neonatal Infant Pain Scale and on nursing notes suggestions of pain. For statistical analysis, the Statistical Package for the Social Sciences was used, and the significance level was set at 5%. there was at least one record of pain in 50.3% of the hospitalizations, according to the pain scale adopted or nursing note. The newborns underwent a mean of 6.6 invasive procedures per day. Only 32.5% of the pain records resulted in the adoption of pharmacological or non-pharmacological intervention for pain relief. newborns are frequently exposed to pain and the low frequency of pharmacological or non-pharmacological interventions reinforces the undertreatment of this condition. determinar a frequência de dor e verificar as medidas realizadas para seu alívio durante os sete primeiros dias de internação na Unidade de Terapia Intensiva Neonatal, bem como identificar o tipo e frequência de procedimentos invasivos aos quais os recém-nascidos foram submetidos. estudo retrospectivo transversal. Das 188 internações ocorridas no período estipulado de 12 meses, 171 foram incluídas na pesquisa. Os dados foram coletados a partir dos prontuários e a presença de dor foi analisada tanto com base na escala de dor Neonatal Infant Pain Scale quanto mediante anotação de enfermagem sugestiva de dor. Para análise estatística, utilizou-se o programa Statistical Package for the Social Sciences, adotando-se nível de significância de 5%. em 50,3% das internações houve ao menos um registro de dor

  15. Forced response of rotating bladed disks: Blade Tip-Timing measurements

    Science.gov (United States)

    Battiato, G.; Firrone, C. M.; Berruti, T. M.

    2017-02-01

    The Blade Tip-Timing is a well-known non-contact measurement technique currently employed for the identification of the dynamic behaviours of rotating bladed disks. Although the measurement system has become a typical industry equipment for bladed disks vibration surveys, the type of sensors, the positioning of the sensors around the bladed disk and the used algorithm for data post-processing are still not standard techniques, and their reliability has to be proved for different operation conditions by the comparison with other well-established measurement techniques used as reference like strain gauges. This paper aims at evaluating the accuracy of a latest generation Tip-Timing system on two dummy blisks characterized by different geometrical, structural and dynamical properties. Both disks are tested into a spin-rig where a fixed number of permanent magnets excite synchronous vibrations with respect to the rotor speed. A new positioning for the Blade Tip-Timing optical sensors is tested in the case of a shrouded bladed disk. Due to the presence of shrouds, the sensors cannot be positioned at the outer radius of the disk pointing radially toward the rotation axis as in the most common applications, since the displacements at the tips are very small and cannot be detected. For this reason a particular placement of optical laser sensors is studied in order to point at the leading and trailing edges' locations where the blades experience the largest vibration amplitudes with the aim of not interfering with the flow path. Besides the typical Blade Tip-Timing application aimed at identifying the dynamical properties of each blade, an original method is here proposed to identify the operative deflection shape of a bladed disk through the experimental determination of the nodal diameters. The method is applicable when a small mistuning pattern perturbs the ideal cyclic symmetry of the bladed disk.

  16. Nursing unit teams matter: Impact of unit-level nurse practice environment, nurse work characteristics, and burnout on nurse reported job outcomes, and quality of care, and patient adverse events--a cross-sectional survey.

    Science.gov (United States)

    Van Bogaert, Peter; Timmermans, Olaf; Weeks, Susan Mace; van Heusden, Danny; Wouters, Kristien; Franck, Erik

    2014-08-01

    To investigate the impact of nurse practice environment factors, nurse work characteristics, and burnout on nurse reported job outcomes, quality of care, and patient adverse events variables at the nursing unit level. Nurse practice environment studies show growing insights and knowledge about determining factors for nurse workforce stability, quality of care, and patient safety. Until now, international studies have primarily focused on variability at the hospital level; however, insights at the nursing unit level can reveal key factors in the nurse practice environment. A cross-sectional design with a survey. In a cross-sectional survey, a sample of 1108 nurses assigned to 96 nursing units completed a structured questionnaire composed of various validated instruments measuring nurse practice environment factors, nurse work characteristics, burnout, nurse reported job outcomes, quality of care, and patient adverse events. Associations between the variables were examined using multilevel modelling techniques. Various unit-level associations (simple models) were identified between nurse practice environment factors, nurse work characteristics, burnout dimensions, and nurse reported outcome variables. Multiple multilevel models showed various independent variables such as nursing management at the unit level, social capital, emotional exhaustion, and depersonalization as important predictors of nurse reported outcome variables such job satisfaction, turnover intentions, quality of care (at the unit, the last shift, and in the hospital within the last year), patient and family complaints, patient and family verbal abuse, patient falls, nosocomial infections, and medications errors. Results suggested a stable nurse work force, with the capability to achieve superior quality and patient safety outcomes, is associated with unit-level favourable perceptions of nurse work environment factors, workload, decision latitude, and social capital, as well low levels of burnout

  17. Investigation of two-stage air-cooled turbine suitable for flight at Mach number of 2.5 II : blade design

    Science.gov (United States)

    Miser, James W; Stewart, Warner L

    1957-01-01

    A blade design study is presented for a two-stage air-cooled turbine suitable for flight at a Mach number of 2.5 for which velocity diagrams have been previously obtained. The detailed procedure used in the design of the blades is given. In addition, the design blade shapes, surface velocity distributions, inner and outer wall contours, and other design data are presented. Of all the blade rows, the first-stage rotor has the highest solidity, with a value of 2.289 at the mean section. The second-stage stator also had a high mean-section solidity of 1.927, mainly because of its high inlet whirl. The second-stage rotor has the highest value of the suction-surface diffusion parameter, with a value of 0.151. All other blade rows have values for this parameter under 0.100.

  18. The 12-m Wind Turbine Blade Manufactured by Vølund A/S and O.L. Boats, Denmark

    DEFF Research Database (Denmark)

    Petersen, H.

    1980-01-01

    A 12 m long glass fiber blade has been developed for use as outer wing panels in the two Danish Nibe windmills. The outer wing is composed of a glass-fiber-reinforced plastic, in the form of a NACA 4412 section at the tip and a NACA 4420 section at the root and with chord and section thickness...... varying linearly along the wing. In bending tests of a 4-m portion of the blade, a compression stress of 137.5 MN/sq m was found to cause failure, and a flapwise bending moment was calculated. Natural frequencies of combined flapwise and chordwise bending have been calculated for the blade fixed...... at the root face and 1 m from the root face and have been verified experimentally. Aerodynamic calculations have also been performed of the power coefficient as a function of tip speed ratio for various tip chord angles for blades used in a 3-bladed and a 2-bladed rotor configuration with a diameter of 26 m....

  19. A Heterogeneous Bayesian Regression Model for Cross-Sectional Data Involving a Single Observation per Response Unit

    Science.gov (United States)

    Fong, Duncan K. H.; Ebbes, Peter; DeSarbo, Wayne S.

    2012-01-01

    Multiple regression is frequently used across the various social sciences to analyze cross-sectional data. However, it can often times be challenging to justify the assumption of common regression coefficients across all respondents. This manuscript presents a heterogeneous Bayesian regression model that enables the estimation of…

  20. A New Method for Horizontal Axis Wind Turbine (HAWT Blade Optimization

    Directory of Open Access Journals (Sweden)

    Mohammadreza Mohammadi

    2016-02-01

    Full Text Available Iran has a great potential for wind energy. This paper introduces optimization of 7 wind turbine blades for small and medium scales in a determined wind condition of Zabol site, Iran, where the average wind speed is considered 7 m /s. Considered wind turbines are 3 bladed and radius of 7 case study turbine blades are 4.5 m, 6.5 m, 8 m, 9 m, 10 m, 15.5 m and 20 m. As the first step, an initial design is performed using one airfoil (NACA 63-215 across the blade. In the next step, every blade is divided into three sections, while the 20 % of first part of the blade is considered as root, the 5% of last the part is considered as tip and the rest of the blade as mid part. Providing necessary input data, suitable airfoils for wind turbines including 43 airfoils are extracted and their experimental data are entered in optimization process. Three variables in this optimization problem would be airfoil type, attack angle and chord, where the objective function is maximum output torque. A MATLAB code was written for design and optimization of the blade, which was validated with a previous experimental work. In addition, a comparison was made to show the effect of optimization with two variables (airfoil type and attack angle versus optimization with three variables (airfoil type, attack angle and chord on output torque increase. Results of this research shows a dramatic increase in comparison to initial designed blade with one airfoil where two variable optimization causes 7.7% to 22.27 % enhancement and three variable optimization causes 17.91% up to 24.48% rise in output torque .Article History: Received Oct 15, 2015; Received in revised form January 2, 2016; Accepted January 14, 2016; Available online How to Cite This Article: Mohammadi, M., Mohammadi, A. and Farahat, S. (2016 A New Method for Horizontal Axis Wind Turbine (HAWT Blade Optimization. Int. Journal of Renewable Energy Development, 5(1,1-8. http://dx.doi.org/10.14710/ijred.5.1.1-8

  1. Low Speed Technology for Small Turbine Development Reaction Injection Molded 7.5 Meter Wind Turbine Blade

    Energy Technology Data Exchange (ETDEWEB)

    David M. Wright; DOE Project Officer - Keith Bennett

    2007-07-31

    An optimized small turbine blade (7.5m radius) was designed and a partial section molded with the RIM (reaction-injection molded polymer) process for mass production. The intended market is for generic three-bladed wind turbines, 100 kilowatts or less, for grid-assist end users with rural and semi-rural sites, such as the farm/ranch market, having low to moderate IEC Class 3-4 wind regimes. This blade will have substantial performance improvements over, and be cheaper than, present-day 7.5m blades. This is made possible by the injection-molding process, which yields high repeatability, accurate geometry and weights, and low cost in production quantities. No wind turbine blade in the 7.5m or greater size has used this process. The blade design chosen uses a RIM skin bonded to a braided infused carbon fiber/epoxy spar. This approach is attractive to present users of wind turbine blades in the 5-10m sizes. These include rebladeing California wind farms, refurbishing used turbines for the Midwest farm market, and other manufacturers introducing new turbines in this size range.

  2. Aeroelastic multidisciplinary design optimization of a swept wind turbine blade

    DEFF Research Database (Denmark)

    Pavese, Christian; Tibaldi, Carlo; Zahle, Frederik

    2017-01-01

    Mitigating loads on a wind turbine rotor can reduce the cost of energy. Sweeping blades produces a structural coupling between flapwise bending and torsion, which can be used for load alleviation purposes. A multidisciplinary design optimization (MDO) problem is formulated including the blade sweep...... against time-domain full design load basis aeroelastic simulations to ensure that they comply with the constraints. A 10-MW wind turbine blade is optimized by minimizing a cost function that includes mass and blade root flapwise fatigue loading. The design space is subjected to constraints that represent...... this achievement, a set of optimized straight blade designs is compared to a set of optimized swept blade designs. Relative to the respective optimized straight designs, the blade mass of the swept blades is reduced of an extra 2% to 3% and the blade root flapwise fatigue damage equivalent load by a further 8%....

  3. Gas turbine blade with metal core and ceramic blade. Gasturbinenschaufel mit Metallkern und Keramikblatt

    Energy Technology Data Exchange (ETDEWEB)

    Huether, W.

    1984-03-29

    This is a gas turbine blade with a metal core connected to the rotor disc and a ceramic profile blade surrounding this core at a certain spacing, where a metal mesh is inserted between the metal core and the ceramic covering.

  4. Multi-piece wind turbine rotor blades and wind turbines incorporating same

    Science.gov (United States)

    Moroz,; Mieczyslaw, Emilian [San Diego, CA

    2008-06-03

    A multisection blade for a wind turbine includes a hub extender having a pitch bearing at one end, a skirt or fairing having a hole therethrough and configured to mount over the hub extender, and an outboard section configured to couple to the pitch bearing.

  5. Multiaxial fatigue of in-service aluminium longerons for helicopter rotor-blades

    Directory of Open Access Journals (Sweden)

    A. Shanyavskiy

    2016-07-01

    Full Text Available Fatigue cracking of longerons manufactured from Al-alloy AVT-1 for helicopter in-service rotorblades was considered and crack growth period and equivalent of tensile stress for different blade sections were estimated. Complicated case of in-service blades multiaxial cyclically bending-rotating and tension can be considered based on introduced earlier master curve constructed for aluminum alloys in the simple case of uniaxial tension with stress R-ratio near to zero. Calculated equivalent tensile stress was compared for different blade sections and it was shown that in-service blades experienced not principle difference in this value in the crack growth direction by the investigated sections. It is not above the designed equivalent stress level. Crack growth period estimation in longerons based on fatigue striation spacing or meso-beach-marks measurements has shown that monitoring system introduced designer in longerons can be effectively used for in-time crack detecting independently on the failed section when can appeared because of various type of material faults or in-service damages.

  6. Design studies for twist-coupled wind turbine blades.

    Energy Technology Data Exchange (ETDEWEB)

    Valencia, Ulyses (Wichita State University, Wichita, KS); Locke, James (Wichita State University, Wichita, KS)

    2004-06-01

    This study presents results obtained for four hybrid designs of the Northern Power Systems (NPS) 9.2-meter prototype version of the ERS-100 wind turbine rotor blade. The ERS-100 wind turbine rotor blade was designed and developed by TPI composites. The baseline design uses e-glass unidirectional fibers in combination with {+-}45-degree and random mat layers for the skin and spar cap. This project involves developing structural finite element models of the baseline design and carbon hybrid designs with and without twist-bend coupling. All designs were evaluated for a unit load condition and two extreme wind conditions. The unit load condition was used to evaluate the static deflection, twist and twist-coupling parameter. Maximum deflections and strains were determined for the extreme wind conditions. Linear and nonlinear buckling loads were determined for a tip load condition. The results indicate that carbon fibers can be used to produce twist-coupled designs with comparable deflections, strains and buckling loads to the e-glass baseline.

  7. Paleoseismology of the Southern Section of the Black Mountains and Southern Death Valley Fault Zones, Death Valley, United States

    Science.gov (United States)

    Sohn, Marsha S.; Knott, Jeffrey R.; Mahan, Shannon

    2014-01-01

    The Death Valley Fault System (DVFS) is part of the southern Walker Lane–eastern California shear zone. The normal Black Mountains Fault Zone (BMFZ) and the right-lateral Southern Death Valley Fault Zone (SDVFZ) are two components of the DVFS. Estimates of late Pleistocene-Holocene slip rates and recurrence intervals for these two fault zones are uncertain owing to poor relative age control. The BMFZ southernmost section (Section 1W) steps basinward and preserves multiple scarps in the Quaternary alluvial fans. We present optically stimulated luminescence (OSL) dates ranging from 27 to 4 ka of fluvial and eolian sand lenses interbedded with alluvial-fan deposits offset by the BMFZ. By cross-cutting relations, we infer that there were three separate ground-rupturing earthquakes on BMFZ Section 1W with vertical displacement between 5.5 m and 2.75 m. The slip-rate estimate is ∼0.2 to 1.8 mm/yr, with an earthquake recurrence interval of 4,500 to 2,000 years. Slip-per-event measurements indicate Mw 7.0 to 7.2 earthquakes. The 27–4-ka OSL-dated alluvial fans also overlie the putative Cinder Hill tephra layer. Cinder Hill is offset ∼213 m by SDVFZ, which yields a tentative slip rate of 1 to 8 mm/yr for the SDVFZ.

  8. Distribution of Defects in Wind Turbine Blades and Reliability Assessment of Blades Containing Defects

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Branner, Kim; Berring, Peter

    2009-01-01

    on the assumption that one error in the production process tends to trigger several defects. For both models additional information about number, type and size of the defects is included as stochastic variables. The probability of failure for a wind turbine blade will not only depend on variations in the material...... properties and the load but also on potential defects in the blades. As a numerical example the probability of failure is calculated for the main spar both with and without defects in terms of delaminations. The delaminations increase the probability of failure compared to a perfect blade, but by applying......In the present paper two stochastic models for the distribution of defects in wind turbine blades are proposed. The first model assumes that the individual defects are completely randomly distributed in the blade. The second model assumes that the defects occur in clusters of different size based...

  9. Wind turbine blade shear web disbond detection using rotor blade operational sensing and data analysis.

    Science.gov (United States)

    Myrent, Noah; Adams, Douglas E; Griffith, D Todd

    2015-02-28

    A wind turbine blade's structural dynamic response is simulated and analysed with the goal of characterizing the presence and severity of a shear web disbond. Computer models of a 5 MW offshore utility-scale wind turbine were created to develop effective algorithms for detecting such damage. Through data analysis and with the use of blade measurements, a shear web disbond was quantified according to its length. An aerodynamic sensitivity study was conducted to ensure robustness of the detection algorithms. In all analyses, the blade's flap-wise acceleration and root-pitching moment were the clearest indicators of the presence and severity of a shear web disbond. A combination of blade and non-blade measurements was formulated into a final algorithm for the detection and quantification of the disbond. The probability of detection was 100% for the optimized wind speed ranges in laminar, 30% horizontal shear and 60% horizontal shear conditions.

  10. CFD Prediction and Experimental Measurement of Blade Water Coverage in a Diesel Turbocharger

    Directory of Open Access Journals (Sweden)

    Jun Yao

    2012-01-01

    Full Text Available A turbocharger unit for diesel engine is often equipped with a built-in online water washing system and its performance is not always satisfactory because of efficiency declination due to deposit accumulated on blade surfaces not being washed away. In this study, a systematic approach of using experimental measurements and computational fluid dynamics (CFD is adopted to analyse liquid/gas two-phase flow associated with a turbocharger water washing system, in order to understand the underlying flow physics. A medium-sized diesel engine turbocharger configuration is chosen for this purpose. Experiments are focussed on blade surface temperature measurements, while CFD modelling with a coupled Eulerian/Lagrangian method is used for capturing the complex gas/liquid two-phase flow behaviours inside the induction duct and the blade passage. It was found that numerical predictions are in a good agreement with experimental data in terms of temperature distributions of the blade leading edge region and water coverage over the blade ring. Other flow features such as the water droplet trajectories and the particle size distributions are also explored and analysed in further details, and they are useful for understanding the deposit removal mechanism.

  11. The Brazier effect in wind turbine blades and its influence on design

    DEFF Research Database (Denmark)

    Jensen, Find Mølholt; Weaver, P.M.; Cecchini, L.S.

    2012-01-01

    Critical failure was observed in the shear web of a wind turbine blade during a full-scale testing. This failure occurred immediately before the ultimate failure and was partly caused by buckling and non-linear cross-sectional strain. Experimental values had been used to compare and validate both...... numerical and semi-analytical results in the analysis of the shear webs in the reinforced wind turbine blade. Only elastic material behaviour was analysed, and attention was primarily focused on the Brazier effect. The complex, geometrically non-linear and elastic stress–strain behaviour of the shear webs...

  12. TWIST SPRINGBACK MEASUREMENT OF AUTONOMOUS UNDERWATER VEHICLE PROPELLER BLADE BASED ON PROFILE DEVIATION

    Directory of Open Access Journals (Sweden)

    Ahmad Baharuddin Abdullah

    2013-01-01

    Full Text Available Geometrical defects that are attributable to springback are among the major defects induced by the sheet metal forming process. Such defects are critical for sections with varying thickness, such as Autonomous Underwater Vehicle (AUV propeller blades. In this study, the springback in the twist-bending of an AA6061 propeller blade was quantified by comparing the targeted and manufactured profiles obtained using the commercial three-dimensional surface measurement technique. The results show that the twist springback becomes larger as the twist angle increases. Similarly, the twist springback increases with increasing deformation ratio.

  13. Successful Solutions to SSME/AT Development Turbine Blade Distress

    Science.gov (United States)

    Montgomery, Stuart K.

    1999-01-01

    As part of the High-Pressure Fuel Turbopump/Alternate Turbopump (HPFTP/AT) turbine blade development program, unique turbine blade design features were implemented to address 2nd stage turbine blade high cycle fatigue distress and improve turbine robustness. Features included the addition of platform featherseal dampers, asymmetric blade tip seal segments, gold plating of the blade attachments, and airfoil tip trailing edge modifications. Development testing shows these features have eliminated turbine blade high cycle fatigue distress and consequently these features are currently planned for incorporation to the flight configuration. Certification testing will begin in 1999. This presentation summarizes these features.

  14. Further development of the swinging-blade Savonius rotor

    Science.gov (United States)

    Aldoss, T. K.; Najjar, Y. S. H.

    Savonius rotor performance is improved by allowing both downwind and upwind rotor blades to swing back through an optimum angle. This will minimize the drag on the upwind blade and maximize the drag on the down-wind blade. A combination of 50 degrees upwind blade swing angle and 13.5 degrees downwind blade swing angle have been found experimentally to be the optimum swing angles that increased the rotor maximum power coefficient to about 23.5 percent compared with 18 percent with optimum upwind blade swing alone.

  15. Optimal Design and Acoustic Assessment of Low-Vibration Rotor Blades

    Directory of Open Access Journals (Sweden)

    G. Bernardini

    2016-01-01

    Full Text Available An optimal procedure for the design of rotor blade that generates low vibratory hub loads in nonaxial flow conditions is presented and applied to a helicopter rotor in forward flight, a condition where vibrations and noise become severe. Blade shape and structural properties are the design parameters to be identified within a binary genetic optimization algorithm under aeroelastic stability constraint. The process exploits an aeroelastic solver that is based on a nonlinear, beam-like model, suited for the analysis of arbitrary curved-elastic-axis blades, with the introduction of a surrogate wake inflow model for the analysis of sectional aerodynamic loads. Numerical results are presented to demonstrate the capability of the proposed approach to identify low vibratory hub loads rotor blades as well as to assess the robustness of solution at off-design operating conditions. Further, the aeroacoustic assessment of the rotor configurations determined is carried out in order to examine the impact of low-vibration blade design on the emitted noise field.

  16. Wind Tunnel Study of the Electro-Thermal De-Icing of Wind Turbine Blades

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, C.; Ilinca, A.; Fortin, G.; Perron, J. [Anti-icing Materials International Laboratory, Universite du Quebec a Chicoutimi, Quebec, Canada and Wind Energy Group, Universite du Quebec a Rimouski, Quebec (Canada)

    2007-07-01

    Most of the wind turbines operating in cold climates are facing icing events but very few of them are equipped with blade de-icing systems. Few studies were performed and published on the characteristics of these de-icing systems. In order to optimize the design and power consumption of an electro-thermal de-icing system for wind turbine blades, an experimental set-up was built and used to test the system under icing conditions in a refrigerated wind tunnel. The parameters of the de-icing control system consider only the convective heat transfer at the blade surface during ice accretion. Meteorological data are those gathered from Murdochville's experimental site in Canada. The blade airfoil is a NACA 63 415 and the icing conditions are scaled to be simulated in the icing wind tunnel section. The results show the relation between the meteorological conditions, the ridge formed by liquid water runback, the heating power and the airfoil surface temperature. The study provides useful data for the design of electro-thermal deicing systems for wind turbine blade application.

  17. A Low Order Model for Analyzing effects of Blade Fatigue Load Control

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    2006-01-01

    , and torsional blade oscillations, and rotor speed). The aerodynamics is described by a model of unsteady aerodynamic. The equations of motion are derived in nonlinear and linear form. The linear equations of motion are used for stability analysis and control design. The nonlinear equations of motion are used...... for time simulations to evaluate control performance. The stability analysis shows that the model is capable of predicting classical flutter, and stall-induced vibrations. The results from the stability analysis are compared with known results, showing good agreement. The model is used to compare......A new low order mathematical model is introduced to analyse blade dynamics and blade load reducing control strategies for wind turbines. The model consists of a typical wing section model combined with a rotor speed model, leading to four structural degrees of freedom (flapwise, edgewise...

  18. Blade containment evaluation of civil aircraft engines

    Institute of Scientific and Technical Information of China (English)

    Yang Bin

    2013-01-01

    The potential hazard resulting from uncontained turbine engine rotor blade failure has always been the long-term concern of each aero engine manufacturer,and to fully contain the failed blades under critical operating conditions is also one of the most important considerations to meet the rotor integrity requirements.Usually,there are many factors involving the engine containment capability which need to be reviewed during the engine design phases,such as case thickness,rotor support structure,blade weight and shape,etc.However,the premier method to demonstrate the engine containment capability is the fan blade-off test and margin of safety (MS) analysis.Based on a concrete engine model,this paper aims to explain the key points of aero engine containment requirements in FAR Part 33,and introduces the implementation of MS analysis and fan blade-off test in the engine airworthiness certification.Through the introduction,it would be greatly helpful to the industrial community to evaluate the engine containment capability and prepare the final test demonstration in engine certification procedure.

  19. Modal analysis of wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, G.C.; Hansen, M.H.; Baumgart, A.; Carlen, I.

    2002-02-01

    The modal analysis technique has been used to identify essential dynamic properties of wind turbine blades like natural frequencies, damping characteristics and mode shapes. Different experimental procedures have been considered, and the most appropriate of these has been selected. Although the comparison is based on measurements on a LM 19 m blade, the recommendations given are believed to be valid for other wind turbine blades as well. The reliability of the selected experimental analysis has been quantified by estimating the unsystematic variations in the experimental findings. Satisfactory results have been obtained for natural frequencies, damping characteristics and for the dominating deflection direction of the investigated mode shapes. For the secondary deflection directions, the observed experimental uncertainty may be considerable - especially for the torsional deflection. The experimental analysis of the LM 19 m blade has been compared with results from a state-of-the-art FE-modeling of the same blade. For some of the higher modes substantial discrepancies between the natural frequencies originating from the FE-modeling and the modal analysis, respectively, are observed. In general the qualitative features of measured and computed modes shapes are in good agreement. However, for the secondary deflection directions, substantial deviations in the absolute values may occur (when normalizing with respect to the primary deflection direction). Finally, suggestions of potential future improvements of the experimental procedure are discussed. (au)

  20. Blade manipulators in turbulent channel flow

    Science.gov (United States)

    Vasudevan, B.; Prabhu, A.; Narasimha, R.

    1992-01-01

    We report here the results of a series of careful experiments in turbulent channel flow, using various configurations of blade manipulators suggested as optimal in earlier boundary layer studies. The mass flow in the channel could be held constant to better than 0.1%, and the uncertainties in pressure loss measurements were less than 0.1 mm of water; it was therefore possible to make accurate estimates of the global effects of blade manipulation of a kind that are difficult in boundary layer flows. The flow was fully developed at the station where the blades were mounted, and always relaxed to the same state sufficiently far downstream. It is found that, for a given mass flow, the pressure drop to any station downstream is always higher in the manipulated than in the unmanipulated flow, demonstrating that none of the blade manipulators tried reduces net duct losses. However the net increase in duct losses is less than the drag of the blade even in laminar flow, showing that there is a net reduction in the total skin friction drag experienced by the duct, but this relief is only about 20% of the manipulator drag at most.

  1. 3X-100 blade field test.

    Energy Technology Data Exchange (ETDEWEB)

    Zayas, Jose R.; Johnson, Wesley D.

    2008-03-01

    In support of a Work-For-Other (WFO) agreement between the Wind Energy Technology Department at Sandia National Laboratories and 3TEX, one of the three Micon 65/13M wind turbines at the USDA Agriculture Research Service (ARS) center in Bushland, Texas, has been used to test a set of 9 meter wind turbine blades, manufactured by TPI composites using the 3TEX carbon material for the spar cap. Data collected from the test has been analyzed to evaluate both the aerodynamic performance and the structural response from the blades. The blades aerodynamic and structural performance, the meteorological inflow and the wind turbine structural response has been monitored with an array of 57 instruments: 15 to characterize the blades, 13 to characterize inflow, and 15 to characterize the time-varying state of the turbine. For the test, data was sampled at a rate of 40 Hz using the ATLAS II (Accurate GPS Time-Linked Data Acquisition System) data acquisition system. The system features a time-synchronized continuous data stream and telemetered data from the turbine rotor. This paper documents the instruments and infrastructure that have been developed to monitor these blades, turbines and inflow, as well as both modeling and field testing results.

  2. Unified continuum damage model for matrix cracking in composite rotor blades

    Energy Technology Data Exchange (ETDEWEB)

    Pollayi, Hemaraju; Harursampath, Dineshkumar [Nonlinear Multifunctional Composites - Analysis and Design Lab (NMCAD Lab) Department of Aerospace Engineering Indian Institute of Science Bangalore - 560012, Karnataka (India)

    2015-03-10

    This paper deals with modeling of the first damage mode, matrix micro-cracking, in helicopter rotor/wind turbine blades and how this effects the overall cross-sectional stiffness. The helicopter/wind turbine rotor system operates in a highly dynamic and unsteady environment leading to severe vibratory loads present in the system. Repeated exposure to this loading condition can induce damage in the composite rotor blades. These rotor/turbine blades are generally made of fiber-reinforced laminated composites and exhibit various competing modes of damage such as matrix micro-cracking, delamination, and fiber breakage. There is a need to study the behavior of the composite rotor system under various key damage modes in composite materials for developing Structural Health Monitoring (SHM) system. Each blade is modeled as a beam based on geometrically non-linear 3-D elasticity theory. Each blade thus splits into 2-D analyzes of cross-sections and non-linear 1-D analyzes along the beam reference curves. Two different tools are used here for complete 3-D analysis: VABS for 2-D cross-sectional analysis and GEBT for 1-D beam analysis. The physically-based failure models for matrix in compression and tension loading are used in the present work. Matrix cracking is detected using two failure criterion: Matrix Failure in Compression and Matrix Failure in Tension which are based on the recovered field. A strain variable is set which drives the damage variable for matrix cracking and this damage variable is used to estimate the reduced cross-sectional stiffness. The matrix micro-cracking is performed in two different approaches: (i) Element-wise, and (ii) Node-wise. The procedure presented in this paper is implemented in VABS as matrix micro-cracking modeling module. Three examples are presented to investigate the matrix failure model which illustrate the effect of matrix cracking on cross-sectional stiffness by varying the applied cyclic load.

  3. Experimental development of a torsion arc blade type horizontal axis windmil; Nejire enko yokugata suihei jiku fusha no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, N. [Meiji Univ., Tokyo (Japan). Faculty of Scince and Technology

    1996-05-31

    To get more wind energy, longer rotating blades and higher towers of windmills are required. Therefore, the location of windmills is limited and the initial cost gets higher. In this study, a small size windmill which can generate electricity even in a city was developed and tested. A torsion arc blade type horizontal axis windmill was designed and the blade form, number and degree of distortion were investigated. Based on the results, a small windmill was made, rotation and generation tests were carried out and it was confirmed that the windmill could be used as a small scale wind power generation. The windmill is of simple construction having 6 arc blades and no high tower is required. This paper consists of 6 sections, i.e. Introduction, Windmill model, Tested windmill, Test facility and method, Test results and consideration, and Postscript. 2 refs., 18 figs., 1 tab.

  4. Attitudes of dermatologists in the southeastern United States regarding treatment of alopecia areata: a cross-sectional survey study

    Directory of Open Access Journals (Sweden)

    Stewart Paul W

    2009-11-01

    Full Text Available Abstract Background Little evidence exists to guide treatment of alopecia areata (AA. The current practices in treatment of children compared to adults and of progressive stages of hair loss are unknown. The objective of this study was to examine the current practices of southeastern United States dermatologists for the treatment of AA. Methods Dermatologists were sent anonymous questionnaires regarding their treatment practices by mail. Respondents' frequencies of treatment in children compared to adults and in patchy hair loss compared to widespread hair loss were compared with Wilcoxon signed-ranks tests and Friedman tests. As a secondary source, the National Alopecia Areata Registry (NAAR database was analyzed for patients' treatment histories. Results Survey results suggested that dermatologists recommend treatment less frequently for children than adults and for more advanced hair loss. NAAR data confirmed that offering no treatment for AA is relatively common. Conclusion Dermatologists' treatment of AA is inconsistent. A stronger evidence base will provide more consistent treatment options.

  5. Piezoelectric Vibration Damping Study for Rotating Composite Fan Blades

    Science.gov (United States)

    Min, James B.; Duffy, Kirsten P.; Choi, Benjamin B.; Provenza, Andrew J.; Kray, Nicholas

    2012-01-01

    Resonant vibrations of aircraft engine blades cause blade fatigue problems in engines, which can lead to thicker and aerodynamically lower performing blade designs, increasing engine weight, fuel burn, and maintenance costs. In order to mitigate undesirable blade vibration levels, active piezoelectric vibration control has been investigated, potentially enabling thinner blade designs for higher performing blades and minimizing blade fatigue problems. While the piezoelectric damping idea has been investigated by other researchers over the years, very little study has been done including rotational effects. The present study attempts to fill this void. The particular objectives of this study were: (a) to develop and analyze a multiphysics piezoelectric finite element composite blade model for harmonic forced vibration response analysis coupled with a tuned RLC circuit for rotating engine blade conditions, (b) to validate a numerical model with experimental test data, and (c) to achieve a cost-effective numerical modeling capability which enables simulation of rotating blades within the NASA Glenn Research Center (GRC) Dynamic Spin Rig Facility. A numerical and experimental study for rotating piezoelectric composite subscale fan blades was performed. It was also proved that the proposed numerical method is feasible and effective when applied to the rotating blade base excitation model. The experimental test and multiphysics finite element modeling technique described in this paper show that piezoelectric vibration damping can significantly reduce vibrations of aircraft engine composite fan blades.

  6. Service failure of hot-stage turbine blades:

    Science.gov (United States)

    Oldfield, William; Oldfield, Freda M.

    1993-10-01

    Surface-connected porosity in current military aircraft hot-stage turbine engine blades is associated with blade failure. Oxidation ratcheting is suggested as the failure mechanism. Sta- tistical comparison of new and used blade populations showed that for blades cast with an equiaxed structure, the porosity in new blades was associated with crack formation on the con- cave surface of the used blades. The pores did not tend to develop into cracks on the compressed (convex) surface of the blade. Insufficient suitable data on directionally solidified blades pre- vented similar statistical correlations. However, metallography of the directionally solidified blades showed that the in-service cracks were related to oxidation inside surface-connected pores and that the cracks were oriented in the same direction as the (axial) casting pores. Thus, the proposed failure mechanism through ratcheting is based on the following insights: (1) the blades are thermally cycled as a normal part of service; (2) the hot blades expand and the open pores are filled with oxide; (3) when the blade is cooled, thermal contraction of the metal is greater than the oxide, causing compressive stress and yield; and (4) thermal expansion of the blades opens the pores again, since yield relaxed compressive stress at low temperature. These insights were supported by metallographic and computer-simulation studies which showed that the pores grow 20 to 50 pct in width per 100 missions (about 90 hours of operation) for a military aircraft on a typical mission profile.

  7. Experiments of Wind Turbine Blades with Rocket Triggered Lightning

    Science.gov (United States)

    Minowa, Masayuki; Sumi, Shinichi; Minami, Masayasu; Horii, Kenji

    This paper describes the results of the experiments of wind turbine blades with rocket triggered lightning. A number of wind power stations have been projected and planted. Lightning damage to wind turbines has been an increasing problem recently. So development on protection of wind power plants from lightning is necessary to be fully run for the future. In the experiments, the 1.8m long blade was struck by the lightning discharge triggered by rocket. For the blade kept dry inside, the very strong discharge of positive peak current 28kV, total charge 520 Coulombs, was triggered, but the breakdown did not occur through the blade into inside. Another blade polluted by salty wet inside was struck by the lightning discharge of negative peak current of 4kA with 0.5 Coulombs. The lightning was small, nevertheless, the blade was broken at the upper edge and the blade was disconnected by crack. For the protection of blade, the blade surface was covered with stainless steel plate. The blade itself was safe when the big positive lightning discharged, while most part of stainless steel cover was burned out. Supplement breakdown tests of wind turbine blade were carried out with lightning impulse voltage in laboratory. As a result, it became clear that the blade kept dry inside was an effective lightning protection of wind turbine blades.

  8. 教学设计——Unit4Where's my backpack?Section B(1a-4)

    Institute of Scientific and Technical Information of China (English)

    孙荣

    2011-01-01

    @@ 本单元是在前面学生掌握了陈述句、一般疑间句的基础上,第一次让学生接触特殊疑问句,用"Where"句型讨论"物品的位置"这一话题.Section A通过图片向学生展示了房间里各项物品的名称及它们的摆放位置,并通过对话、听力、找不同的游戏帮助学生掌握如何询问和描述物品的方位.

  9. Measurements of wakes originated from 2-bladed and 3-bladed rotors

    Science.gov (United States)

    Wu, Yu-Ting; Lyu, Shao-Dong; Chen, Bo-Wei

    2016-04-01

    Measurements of wakes originated from 2-bladed and 3-bladed rotors were carried out using a hot-wire probe system in an open jet wind tunnel. Hot-wire anemometry was adopted to characterize the spanwise profiles of mean wind speed, turbulence intensity and momentum flux for downwind locations at 0.5, 1, 2, 3, and 4 rotor diameters. The results showed that the 2-bladed rotor spun faster than the 3-bladed one, where the ratio of the two blade angular velocities was 1.065:1 under the same inflow condition with a uniform distribution of 5.4 m/s flow velocity. The turbulence flow statistics of the rotor wakes showed that the wake originated from the 3-bladed rotor has larger velocity deficit, streamwise turbulence intensity, momentum flux magnitude, but smaller spanwise turbulence intensity. The velocity spectrum showed peaks associated with the presence of the blade-induced tip vortices in the near wake region (approximately within 3 rotor diameters).

  10. Aerodynamics of Rotor Blades for Quadrotors

    CERN Document Server

    Bangura, Moses; Naldi, Roberto; Mahony, Robert

    2016-01-01

    In this report, we present the theory on aerodynamics of quadrotors using the well established momentum and blade element theories. From a robotics perspective, the theoretical development of the models for thrust and horizontal forces and torque (therefore power) are carried out in the body fixed frame of the quadrotor. Using momentum theory, we propose and model the existence of a horizontal force along with its associated power. Given the limitations associated with momentum theory and the inadequacy of the theory to account for the different powers represented in a proposed bond graph lead to the use of blade element theory. Using this theory, models are then developed for the different quadrotor rotor geometries and aerodynamic properties including the optimum hovering rotor used on the majority of quadrotors. Though this rotor is proven to be the most optimum rotor, we show that geometric variations are necessary for manufacturing of the blades. The geometric variations are also dictated by a desired th...

  11. Bolt Cutter Blade's Imprint in Toolmarks Examination.

    Science.gov (United States)

    Volkov, Nikolai; Finkelstein, Nir; Novoselsky, Yehuda; Tsach, Tsadok

    2015-11-01

    Bolt cutters are known as cutting tools which are used for cutting hard objects and materials, such as padlocks and bars. Bolt cutter blades leave their imprint on the cut objects. When receiving a cut object from a crime scene, forensic toolmarks examiners can determine whether the suspected cutting tool was used in a specific crime or not based on class characteristic marks and individual marks that the bolt cutter blades leave on the cut object. The paper presents preliminary results of a study on ten bolt cutters and suggests a quick preliminary examination-the comparison between the blade thickness and the width of the imprint left by the tool on the cut object. Based on the comparison result, if there is not a match, the examiner can eliminate the feasibility of the use of the suspected cutting tool in a specific crime. This examination simplifies and accelerates the comparison procedure.

  12. Microtextured Surfaces for Turbine Blade Impingement Cooling

    Science.gov (United States)

    Fryer, Jack

    2014-01-01

    Gas turbine engine technology is constantly challenged to operate at higher combustor outlet temperatures. In a modern gas turbine engine, these temperatures can exceed the blade and disk material limits by 600 F or more, necessitating both internal and film cooling schemes in addition to the use of thermal barrier coatings. Internal convective cooling is inadequate in many blade locations, and both internal and film cooling approaches can lead to significant performance penalties in the engine. Micro Cooling Concepts, Inc., has developed a turbine blade cooling concept that provides enhanced internal impingement cooling effectiveness via the use of microstructured impingement surfaces. These surfaces significantly increase the cooling capability of the impinging flow, as compared to a conventional untextured surface. This approach can be combined with microchannel cooling and external film cooling to tailor the cooling capability per the external heating profile. The cooling system then can be optimized to minimize impact on engine performance.

  13. A Cross-Sectional Study on Selected Correlates of High risk Sexual Behavior in Polish Migrants Resident in the United Kingdom.

    Science.gov (United States)

    Ganczak, Maria; Czubińska, Grażyna; Korzeń, Marcin; Szych, Zbigniew

    2017-04-14

    Objective: To assess the correlates of the high risk sexual behaviors of Polish migrants in the United Kingdom (UK) after 2004, and to compare such behaviors before/after immigration. Methods: In 2013, a cross-sectional study was conducted through the use of a Computer-assisted web interviewing surveying technique with the use of a self-administered questionnaire. Results: Among 408 respondents (56.9% women), with a median age of 32 years, significantly more admitted to having unprotected sexual contact with a casual partner while in the UK (p sexual behavior among Polish migrants, and to introduce interventions to promote an awareness of HIV sero-status.

  14. Linearization of friction effects in vibration of two rotating blades

    Directory of Open Access Journals (Sweden)

    Hajžman M.

    2013-06-01

    Full Text Available This paper is aimed at modelling of friction effects in blade shrouding which are realized by means of friction elements placed between blades. In order to develop a methodology of modelling, two blades with one friction element in between are considered only. Flexible blades fixed to a rotating disc are discretized by FEM using 1D Rayleigh beam elements derived in rotating space as well as the friction element modelled as a rigid body. The blades and the friction element are connected through two concurrent friction planes, where the friction forces arise on the basis of centrifugal force acting on the friction element. The linearization of friction is performed using the harmonic balance method to determine equivalent damping coefficients in dependence on the amplitudes of relative slip motion between the blades and the friction element. The methodology is applied to a model of two real blades and will be extended for the whole bladed disc with shrouding.

  15. Computational method for the design of wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Vitale, A.J. [Instituto Argentino de Oceanografia, Camino La Carrindanga Km. 7.5, CC 804, B8000FWB Bahia Blanca (Argentina); Universidad Tecnologica Nacional Facultad Regional Bahia Blanca, GESE, 11 de Abril 461, B8000LMI Bahia Blanca (Argentina); Universidad Nacional del Sur, Dpto. de Ing. Electrica y de Computadoras, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Rossi, A.P. [Universidad Tecnologica Nacional Facultad Regional Bahia Blanca, GESE, 11 de Abril 461, B8000LMI Bahia Blanca (Argentina); Universidad Nacional del Sur, Dpto. de Ing. Electrica y de Computadoras, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

    2008-07-15

    Zeus Disenador was developed to design low-power, horizontal-axis wind turbine blades, by means of an iterative algorithm. With this software, it is possible to obtain the optimum blade shape for a wind turbine to satisfy energy requirements of an electric system with optimum rotor efficiency. The number of blades, the airfoil curves and the average wind velocity can be specified by the user. The user can also request particular edge conditions for the width of the blades and for the pitch angle. Results are provided in different windows. Two- and three-dimensional graphics show the aspect of the resultant blade. Numerical results are displayed for blade length, blade surface, pitch angle variation along the blade span, rotor angular speed, rotor efficiency and rotor output power. Software verifications were made by comparing rotor power and rotor efficiency for different designs. Results were similar to those provided by commercial wind generator manufacturers. (author)

  16. Wind blade spar cap and method of making

    Science.gov (United States)

    Mohamed, Mansour H [Raleigh, NC

    2008-05-27

    A wind blade spar cap for strengthening a wind blade including an integral, unitary three-dimensional woven material having a first end and a second end, corresponding to a root end of the blade and a tip end of the blade, wherein the material tapers in width from the first to the second end while maintaining a constant thickness and decreasing weight therebetween, the cap being capable of being affixed to the blade for providing increased strength with controlled variation in weight from the root end to the tip end based upon the tapered width of the material thereof. The present inventions also include the method of making the wind blade spar cap and a wind blade including the wind blade spar cap.

  17. Advances in wind turbine blade design and materials

    DEFF Research Database (Denmark)

    Wind energy is gaining critical ground in the area of renewable energy, with wind energy being predicted to provide up to 8% of the world’s consumption of electricity by 2021. Advances in wind turbine blade design and materials reviews the design and functionality of wind turbine rotor blades...... as well as the requirements and challenges for composite materials used in both current and future designs of wind turbine blades. Part one outlines the challenges and developments in wind turbine blade design, including aerodynamic and aeroelastic design features, fatigue loads on wind turbine blades......, and characteristics of wind turbine blade airfoils. Part two discusses the fatigue behavior of composite wind turbine blades, including the micromechanical modelling and fatigue life prediction of wind turbine blade composite materials, and the effects of resin and reinforcement variations on the fatigue resistance...

  18. Helicopter individual-blade-control and its applications

    Science.gov (United States)

    Ham, N. D.

    1984-01-01

    A new, advanced type of active control for helicopters and its applications are described. The system, based on previously developed M.I.T. Individual-Blade-Control hardware, employs blade-mounted accelerometers to sense blade motion and feeds back information to control blade pitch in such a manner as to reduce the response of selected blade modes. A linear model of the blade and control system dynamics is used to give guidance in the design process as well as to aid in analysis of experimental results. System performance in wind tunnel tests is described, and evidence is given of the system's ability to provide substantial reduction in blade modal responses, including blade bending vibration.

  19. Research overview on vibration damping of mistuned bladed disk assemblies

    Directory of Open Access Journals (Sweden)

    Liang ZHANG

    2016-04-01

    Full Text Available Bladed disk assemblies are very important parts in auto engine and gas turbine, and is widely used in practical engineering. The mistuning existing commonly in the bladed disk assemblies can destroy the vibration characteristics of the bladed disk assemblies, which is one of the reasons for the high cycle fatigue failure of bladed disk assemblies, so it is necessary to research how to reduce the vibration of the bladed disk assemblies. On the basis of the review of relevant research at home and abroad, the mistuning vibration mechanism of the bladed disk assemblies is introduced, and the main technical methods of the vibration damping of bladed disk assemblies are reviewed, such as artificially active mistuning, collision damping, friction damping and optimization of the blade position. Some future research directions are presented.

  20. Dynamic study of a wind turbine blade with horizontal axis

    Energy Technology Data Exchange (ETDEWEB)

    Yousi, R.; El-Batanony, I.; Tritsch, J.B.; Naji, H.; Landjerit, B. [EUDIL, Dept. Mecanique, LML, CNRS URA 1441, 59 - Villeneuve d' Ascq (France)

    2001-04-01

    The study of the dynamic behavior of a wind turbine with horizontal axis can be undertaken by various methods of analysis. The effects of the change of the aerodynamic flow (in the steady and unsteady cases), the variation of parameters of the cinematic movement (angle of attack, pitch angle and yaw angle) and the definition of subsystems characteristics that makes the wind turbine (blade, nacelle and pylon) allow one to characterize the structural dynamic behavior of the wind turbine. It is therefore necessary to develop these items. Once this is done, the structural dynamic behavior of the system can be improved. The term 'improve' means the increase of the life duration by mastering the fatigue effects and the reduction of cost without sacrificing the aerodynamic output. The present study aims to examine the behavior of the blade, which is the main part of the wind turbine in that it that transmits forces to all other parts of the structure. The model is based on the theory of three-dimensional beams, under the assumption of variable sections of the type NACA 4415 airfoil, and takes into account membrane, transversal shear, flexion and free torsion effects. With regards to the aerodynamic loads (the lift, the drag and the pitching moment), a validation has been undertaken by considering experimental data and numerical results obtained by a CFD code (Fluent). The forces are obtained by means of a parametric CAD method interpolation of the aerodynamic poles by Bezier patch under geometrical constraints solved by a Simplex type algorithm. The emphasis is put on dynamic aspects by a complete processing of the dynamic equilibrium equation, applied to the wind turbine blade with horizontal axis. (authors)

  1. The American Medical Association's Section on Surgery: The Beginnings of the Organization, Professionalization, and Specialization of Surgery in the United States.

    Science.gov (United States)

    Rutkow, Ira

    2017-01-01

    To explore the founding of the American Medical Association's Section on Surgery in 1859 and how it represented, on a national basis, the beginnings of organized surgery and the formal start of the professionalization and specialization of surgery in the United States. The broad social process of organization, professionalization, and specialization that began for various disciplines in America in the mid-19th century was a reaction to emerging economic, political, and scientific influences including industrialization, urbanization, and technology. For surgeons or, at least, those men who performed surgical operations, the efforts toward group organization provided a means to promote their skills and restrict competition. An analysis of the published literature, and unpublished documents relating to the creation of the American Medical Association's Section on Surgery. During the 1850s and through the 1870s, a time when surgery was still not considered a separate branch of medicine, the organization of the American Medical Association's Section on Surgery provided the much needed encouragement to surgeons in their quest for professional and specialty recognition. The establishment of the American Medical Association's Section on Surgery in 1859 helped shape the nationwide future of the craft, in particular, surgery's rise as a specialty and profession.

  2. Unsteady transonic flow over cascade blades

    Science.gov (United States)

    Surampudi, S. P.; Adamczyk, J. J.

    1986-01-01

    An attempt is made to develop an efficient staggered cascade blade unsteady aerodynamics model for the neighborhood of March 1, representing the blade row by a rectilinear two-dimensional cascade of thin, flat plate airfoils. The equations of motion are derived on the basis of linearized transonic small perturbation theory, and an analytical solution is obtained by means of the Wiener-Hopf procedure. Making use of the transonic similarity law, the results obtained are compared with those of other linearized cascade analyses. A parametric study is conducted to find the effects of reduced frequency, stagger angle, solidity, and the location of the pitching axis on cascade stability.

  3. Extreme Loading of Aircraft Fan Blade

    CERN Document Server

    Datta, Dibakar

    2013-01-01

    The response of an aircraft fan blade manufactured by composites under the action of static and impact load has been studied in this report. The modeling and analysis of the geometry has been done using CASTEM 2007 version. For the quasi static analysis, the pressure has been incrementally applied until it satisfies the failure criteria. The deformed configuration, strain, Von-Mises stress, and the deflection of the blade have been studied. The response of the system e.g. deformation time history due to the impact of the projectile has been studied where the Newmark method for the dynamic problem has been implemented.

  4. 3D shape optimization of turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Jung, A. [Siemens AG, Muelheim an der Ruhr (Germany). Power Generation Group; Kaemmerer, S. [Stuttgart Univ. (Germany). ITSM; Paffrath, M.; Wever, U. [Siemens AG, Muenchen (Germany). Corporate Technology

    2005-12-15

    In this paper, we present a complete optimization loop in order to maximize the efficiency of turbine blades. The optimization of the shape of turbine blades is considered within the context of a whole turbine stage. Thus, also stator/rotor interactions are taken into account. An essential part of the optimization loop is providing gradient information in order to increase efficiency. The derivation of the sensitivity equation and its discretization within the framework of the underlying flow solver is the main part of the paper. The performance of the optimization loop is demonstrated on a complete turbine stage. (orig.)

  5. Measurement on stages with 3D bladings and different relative width of stator blades

    Directory of Open Access Journals (Sweden)

    Zitek Pavel

    2012-04-01

    Full Text Available Two variants of a stage with modern 3D bladings were tested on a single-stage air turbine to determine the influence of relative width of stator blades (nozzles. The first case means a high-density nozzle row with t/Bax = 0.61; the second one represents a low-density row with t/Bax = 1.12. The 3D shaping of both nozzle cases is based on the same design features. Rotor blades (buckets are kept the same (also 3D shaped. Comparisons of overall stage efficiency as well as measured flow fields data are presented in the paper.

  6. Measurement on stages with 3D bladings and different relative width of stator blades

    Science.gov (United States)

    Milcak, Petr; Hoznedl, Michal; Zitek, Pavel

    2012-04-01

    Two variants of a stage with modern 3D bladings were tested on a single-stage air turbine to determine the influence of relative width of stator blades (nozzles). The first case means a high-density nozzle row with t/Bax = 0.61; the second one represents a low-density row with t/Bax = 1.12. The 3D shaping of both nozzle cases is based on the same design features. Rotor blades (buckets) are kept the same (also 3D shaped). Comparisons of overall stage efficiency as well as measured flow fields data are presented in the paper.

  7. Measurement on stages with 3D bladings and different relative width of stator blades

    OpenAIRE

    Zitek Pavel; Hoznedl Michal; Milcak Petr

    2012-01-01

    Two variants of a stage with modern 3D bladings were tested on a single-stage air turbine to determine the influence of relative width of stator blades (nozzles). The first case means a high-density nozzle row with t/Bax = 0.61; the second one represents a low-density row with t/Bax = 1.12. The 3D shaping of both nozzle cases is based on the same design features. Rotor blades (buckets) are kept the same (also 3D shaped). Comparisons of overall stage efficiency as well as measured flow fields ...

  8. Is the Health and Wellbeing of University Students Associated with their Academic Performance? Cross Sectional Findings from the United Kingdom

    Directory of Open Access Journals (Sweden)

    Walid El Ansari

    2010-02-01

    Full Text Available This study explored the associations between health awareness, health behaviour, subjective health status, and satisfaction of students with their educational experience as independent variables and three outcomes of educational achievement as dependent variables. We undertook two simultaneous cross-sectional surveys among students from one University in the UK during 2008−2009. The first survey was a general health survey; the second survey measured students’ satisfaction with different aspects of their learning and teaching experience. Students’ registration numbers linked the responses of both questionnaires together, and subsequently linked the questionnaires to the university database to import the grades that students actually achieved in their studies. Generally, students (N = 380 exhibited average medium to high satisfaction with their educational experiences. Students’ satisfaction with their educational experiences was not associated with any of the three indicators of educational achievement (actual module mark; perceived own performance; importance of achieving good grades. The associations of educational satisfaction, health, health behaviours, heath complaints and financial parameters with the three outcomes of educational achievement did not differ between male and female students. Each of the health, health behaviours, health complaints and financial parameters were selectively associated with only some but not all three indicators of student educational achievement. We conclude that the findings support a conceptual framework suggesting reciprocal relationships between health, health behaviour and educational achievement. Comprehensive health promotion programmes may have the potential to influence relevant predictors of educational achievement in university students.

  9. Preliminary Evaluation of the Section 1603 Treasury Grant Program for Renewable Power Projects in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Bolinger, Mark; Wiser, Ryan; Darghouth, Naim

    2010-05-05

    This article evaluates the first year of the Section 1603 Treasury cash grant program, which enables renewable power projects in the U.S. to elect cash grants in lieu of the federal tax credits that are otherwise available. To date, the program has been heavily subscribed, particularly by wind power projects, which had received 86% of the nearly $2.6 billion in grants that had been disbursed as of March 1, 2010. As of that date, 6.2 GW of the 10 GW of new wind capacity installed in the U.S. in 2009 had applied for grants in lieu of production tax credits. Roughly 2.4 GW of this wind capacity may not have otherwise been built in 2009 absent the grant program; this 2.4 GW may have supported approximately 51,600 short-term full-time-equivalent (FTE) gross job-years in the U.S. during the construction phase of these wind projects, and 3,860 longterm FTE gross jobs during the operational phase. The program’s popularity stems from the significant economic value that it provides to renewable power projects, relative to the otherwise available tax credits. Although grants reward investment rather than efficient performance, this evaluation finds no evidence at this time of either widespread “gold-plating” or performance problems.

  10. A Cross-Sectional Study of Tobacco Advertising, Promotion, and Sponsorship in Airports across Europe and the United States.

    Science.gov (United States)

    Soong, Andrea; Navas-Acien, Ana; Pang, Yuanjie; Lopez, Maria Jose; Garcia-Esquinas, Esther; Stillman, Frances A

    2016-09-28

    Tobacco advertising, promotion, and sponsorship (TAPS) bans are effective and are increasingly being implemented in a number of venues and countries, yet the state of TAPS in airports and their effect on airport smoking behavior is unknown. The objective of this study was to evaluate the presence of TAPS in airports across Europe and the US, and to begin to examine the relationship between TAPS and smoking behaviors in airports. We used a cross-sectional study design to observe 21 airports in Europe (11) and the US (10). Data collectors observed points of sale for tobacco products, types of products sold, advertisements and promotions, and branding or logos that appeared in the airport. Tobacco products were sold in 95% of all airports, with significantly more sales in Europe than the US. Advertisements appeared mostly in post-security areas; however, airports with advertisements in pre-security areas had significantly more smokers observed outdoors than airports without advertisements in pre-security areas. Tobacco branding appeared in designated smoking rooms as well as on non-tobacco products in duty free shops. TAPS are widespread in airports in Europe and the US and might be associated with outdoor smoking, though further research is needed to better understand any relationship between the two. This study adds to a growing body of research on tobacco control in air transit and related issues. As smoke-free policies advance, they should include comprehensive TAPS bans that extend to airport facilities.

  11. A Cross-Sectional Study of Tobacco Advertising, Promotion, and Sponsorship in Airports across Europe and the United States

    Directory of Open Access Journals (Sweden)

    Andrea Soong

    2016-09-01

    Full Text Available Tobacco advertising, promotion, and sponsorship (TAPS bans are effective and are increasingly being implemented in a number of venues and countries, yet the state of TAPS in airports and their effect on airport smoking behavior is unknown. The objective of this study was to evaluate the presence of TAPS in airports across Europe and the US, and to begin to examine the relationship between TAPS and smoking behaviors in airports. We used a cross-sectional study design to observe 21 airports in Europe (11 and the US (10. Data collectors observed points of sale for tobacco products, types of products sold, advertisements and promotions, and branding or logos that appeared in the airport. Tobacco products were sold in 95% of all airports, with significantly more sales in Europe than the US. Advertisements appeared mostly in post-security areas; however, airports with advertisements in pre-security areas had significantly more smokers observed outdoors than airports without advertisements in pre-security areas. Tobacco branding appeared in designated smoking rooms as well as on non-tobacco products in duty free shops. TAPS are widespread in airports in Europe and the US and might be associated with outdoor smoking, though further research is needed to better understand any relationship between the two. This study adds to a growing body of research on tobacco control in air transit and related issues. As smoke-free policies advance, they should include comprehensive TAPS bans that extend to airport facilities.

  12. A Cross-Sectional Study of Tobacco Advertising, Promotion, and Sponsorship in Airports across Europe and the United States

    Science.gov (United States)

    Soong, Andrea; Navas-Acien, Ana; Pang, Yuanjie; Lopez, Maria Jose; Garcia-Esquinas, Esther; Stillman, Frances A.

    2016-01-01

    Tobacco advertising, promotion, and sponsorship (TAPS) bans are effective and are increasingly being implemented in a number of venues and countries, yet the state of TAPS in airports and their effect on airport smoking behavior is unknown. The objective of this study was to evaluate the presence of TAPS in airports across Europe and the US, and to begin to examine the relationship between TAPS and smoking behaviors in airports. We used a cross-sectional study design to observe 21 airports in Europe (11) and the US (10). Data collectors observed points of sale for tobacco products, types of products sold, advertisements and promotions, and branding or logos that appeared in the airport. Tobacco products were sold in 95% of all airports, with significantly more sales in Europe than the US. Advertisements appeared mostly in post-security areas; however, airports with advertisements in pre-security areas had significantly more smokers observed outdoors than airports without advertisements in pre-security areas. Tobacco branding appeared in designated smoking rooms as well as on non-tobacco products in duty free shops. TAPS are widespread in airports in Europe and the US and might be associated with outdoor smoking, though further research is needed to better understand any relationship between the two. This study adds to a growing body of research on tobacco control in air transit and related issues. As smoke-free policies advance, they should include comprehensive TAPS bans that extend to airport facilities. PMID:27690072

  13. Bamboo as a potential material used for windmill turbine blades

    OpenAIRE

    Xu, Jie; Qin, Yinyao; Zhang, Yu

    2009-01-01

    A mass of studies about windmill turbine blades have been addressed in the recent few decades. This report focus on the development of using bamboo composite materials for producing windmill turbine blades related to the life cycle assessment with sustainable perspective. So we made the problem formulation like this: How can bamboo fibers be used in the design and production of wind mill blades and how would it influence the impact of wind mill blades in a lifecycle perspective? In order to a...

  14. Environmental risk factors associated with Helicobacter pylori seroprevalence in the United States: a cross-sectional analysis of NHANES data.

    Science.gov (United States)

    Krueger, W S; Hilborn, E D; Converse, R R; Wade, T J

    2015-09-01

    Helicobacter pylori imparts a considerable burden to public health. Infections are mainly acquired in childhood and can lead to chronic diseases, including gastric ulcers and cancer. The bacterium subsists in water, but the environment's role in transmission remains poorly understood. The nationally representative National Health and Nutrition Examination Survey (NHANES) was examined for environmental risk factors associated with H. pylori seroprevalence. Data from 1999-2000 were examined and weighted to represent the US population. Multivariable logistic regression estimated adjusted odds ratios (aOR) and 95% confidence intervals (CI) for associations with seropositivity. Self-reported general health condition was inversely associated with seropositivity. Of participants aged <20 years, seropositivity was significantly associated with having a well as the source of home tap water (aOR 1·7, 95% CI 1·1-2·6) and living in a more crowded home (aOR 2·3, 95% CI 1·5-3·7). Of adults aged ⩾20 years, seropositivity was not associated with well water or crowded living conditions, but adults in soil-related occupations had significantly higher odds of seropositivity compared to those in non-soil-related occupations (aOR 1·9, 95% CI 1·2-2·9). Exposures to both well water and occupationally related soil increased the effect size of adults' odds of seropositivity compared to non-exposed adults (aOR 2·7, 95% CI 1·3-5·6). Environmental exposures (well-water usage and occupational contact with soil) play a role in H. pylori transmission. A disproportionate burden of infection is associated with poor health and crowded living conditions, but risks vary by age and race/ethnicity. These findings could help inform interventions to reduce the burden of infections in the United States.

  15. Use of Videoconferencing for Lactation Consultation: An Online Cross-Sectional Survey of Mothers' Acceptance in the United States.

    Science.gov (United States)

    Habibi, Mona F; Springer, Cary M; Spence, Marsha L; Hansen-Petrik, Melissa B; Kavanagh, Katherine F

    2017-06-01

    Suboptimal breastfeeding duration and exclusivity rates are a public health concern. Therefore, there is a need for identifying effective tools for use in interventions targeting specific barriers to optimal breastfeeding outcomes. Research aim: This study aimed to assess the relationship between acceptance of remote lactation consultation using videoconferencing and (a) maternal demographic factors, (b) technology acceptance subscales, (c) maternal learning style preferences, and (d) other potentially explanatory maternal factors. This was a cross-sectional, online study. English-speaking mothers of at least 18 years of age, with an infant age 4 months or younger, and who reported initiating breastfeeding were eligible to participate. Mothers were recruited from 27 randomly selected states. One hundred one mothers completed the survey, resulting in a response rate of 71%. The main outcome was acceptance of videoconferencing use for lactation consultation. No significant differences were found in acceptance by maternal demographic factors or learning style preferences. Acceptance was significantly related to perceived ease of use ( r = .680, p < .001), perceived usefulness/extrinsic motivation ( r = .774, p < .001), intrinsic motivation ( r = .689, p < .001), desire for control of privacy ( r = -.293, p < .01), and mother's perception of the infant father's/maternal partner's acceptance of videoconferencing for lactation consultation ( r = .432, p < .001). Only perceived usefulness/extrinsic motivation and maternal age remained in the final regression model ( R(2) = .616, p < .001). Although perceived usefulness/extrinsic motivation was positively associated with acceptance, maternal age was inversely related. This sample of mothers indicated general acceptance of videoconferencing for lactation consultation, with younger mothers and those perceiving it to be more useful demonstrating greater acceptance.

  16. Digital radiographic technology; non-destructive testing of tubine blades

    NARCIS (Netherlands)

    Penumadu, P.S.

    2014-01-01

    Inspection of turbine blades has always been a big challenge. Any irregularities in the blade have a huge impact on the gas turbine, so these blades have to be manufactured and inspected in the most sophisticated way possible. The evolution of digital radiographic technology took a leap forward to

  17. Digital radiographic technology; non-destructive testing of tubine blades

    NARCIS (Netherlands)

    Penumadu, P.S.

    2014-01-01

    Inspection of turbine blades has always been a big challenge. Any irregularities in the blade have a huge impact on the gas turbine, so these blades have to be manufactured and inspected in the most sophisticated way possible. The evolution of digital radiographic technology took a leap forward to s

  18. Multidisciplinary design optimization of film-cooled gas turbine blades

    Directory of Open Access Journals (Sweden)

    Talya Shashishekara S.

    1999-01-01

    Full Text Available Design optimization of a gas turbine blade geometry for effective film cooling toreduce the blade temperature has been done using a multiobjective optimization formulation. Three optimization formulations have been used. In the first, the average blade temperature is chosen as the objective function to be minimized. An upper bound constraint has been imposed on the maximum blade temperature. In the second, the maximum blade temperature is chosen as the objective function to be minimized with an upper bound constraint on the average blade temperature. In the third formulation, the blade average and maximum temperatures are chosen as objective functions. Shape optimization is performed using geometric parameters associated with film cooling and blade external shape. A quasi-three-dimensional Navier–Stokes solver for turbomachinery flows is used to solve for the flow field external to the blade with appropriate modifications to incorporate the effect of film cooling. The heat transfer analysis for temperature distribution within the blade is performed by solving the heat diffusion equation using the finite element method. The multiobjective Kreisselmeier–Steinhauser function approach has been used in conjunction with an approximate analysis technique for optimization. The results obtained using both formulations are compared with reference geometry. All three formulations yield significant reductions in blade temperature with the multiobjective formulation yielding largest reduction in blade temperature.

  19. Development of a novel walkability index for London, United Kingdom: cross-sectional application to the Whitehall II Study.

    Science.gov (United States)

    Stockton, Jemima C; Duke-Williams, Oliver; Stamatakis, Emmanuel; Mindell, Jennifer S; Brunner, Eric J; Shelton, Nicola J

    2016-05-18

    Physical activity is essential for health; walking is the easiest way to incorporate activity into everyday life. Previous studies report positive associations between neighbourhood walkability and walking but most focused on cities in North America and Australasia. Urban form with respect to street connectivity, residential density and land use mix-common components of walkability indices-differs in European cities. The objective of this study was to develop a walkability index for London and test the index using walking data from the Whitehall II Study.  A neighbourhood walkability index for London was constructed, comprising factors associated with walking behaviours: residential dwelling density, street connectivity and land use mix. Three models were produced that differed in the land uses included. Neighbourhoods were operationalised at three levels of administrative geography: (i) 21,140 output areas, (ii) 633 wards and (iii) 33 local authorities. A neighbourhood walkability score was assigned to each London-dwelling Whitehall II Study participant (2003-04, N = 3020, mean ± SD age = 61.0 years ± 6.0) based on residential postcode. The effect of changing the model specification and the units of enumeration on spatial variation in walkability was examined. There was a radial decay in walkability from the centre to the periphery of London. There was high inter-model correlation in walkability scores for any given neighbourhood operationalisation (0.92-0.98), and moderate-high correlation between neighbourhood operationalisations for any given model (0.39-0.70). After adjustment for individual level factors and area deprivation, individuals in the most walkable neighbourhoods operationalised as wards were more likely to walk >6 h/week (OR = 1.4; 95 % CI: 1.1-1.9) than those in the least walkable. Walkability was associated with walking time in adults. This walkability index could help urban planners identify and design neighbourhoods in

  20. System Integration of the Horizontal-Axis Wind Turbine: The Design of Turbine Blades with an Axial-Flux Permanent Magnet Generator

    Directory of Open Access Journals (Sweden)

    Chi-Jeng Bai

    2014-11-01

    Full Text Available In designing a horizontal-axis wind turbine (HAWT blade, system integration between the blade design and the performance test of the generator is important. This study shows the aerodynamic design of a HAWT blade operating with an axial-flux permanent magnet (AFPM generator. An experimental platform was built to measure the performance curves of the AFPM generator for the purpose of designing the turbine blade. An in-house simulation code was developed based on the blade element momentum (BEM theory and was used to lay out the geometric shape of the turbine blade, including the pitch angle and chord length at each section. This simulation code was combined with the two-dimensional (2D airfoil data for predicting the aerodynamic performance of the designed blades. In addition, wind tunnel experiments were performed to verify the simulation results for the various operating conditions. By varying the rotational speeds at four wind speeds, the experimental and simulation results for the mechanical torques and powers presented good agreement. The mechanical power of the system, which maximizes at the best operating region, provided significant information for designing the HAWT blade.

  1. Effect of linear and non-linear blade modelling techniques on simulated fatigue and extreme loads using Bladed

    Science.gov (United States)

    Beardsell, Alec; Collier, William; Han, Tao

    2016-09-01

    There is a trend in the wind industry towards ever larger and more flexible turbine blades. Blade tip deflections in modern blades now commonly exceed 10% of blade length. Historically, the dynamic response of wind turbine blades has been analysed using linear models of blade deflection which include the assumption of small deflections. For modern flexible blades, this assumption is becoming less valid. In order to continue to simulate dynamic turbine performance accurately, routine use of non-linear models of blade deflection may be required. This can be achieved by representing the blade as a connected series of individual flexible linear bodies - referred to in this paper as the multi-part approach. In this paper, Bladed is used to compare load predictions using single-part and multi-part blade models for several turbines. The study examines the impact on fatigue and extreme loads and blade deflection through reduced sets of load calculations based on IEC 61400-1 ed. 3. Damage equivalent load changes of up to 16% and extreme load changes of up to 29% are observed at some turbine load locations. It is found that there is no general pattern in the loading differences observed between single-part and multi-part blade models. Rather, changes in fatigue and extreme loads with a multi-part blade model depend on the characteristics of the individual turbine and blade. Key underlying causes of damage equivalent load change are identified as differences in edgewise- torsional coupling between the multi-part and single-part models, and increased edgewise rotor mode damping in the multi-part model. Similarly, a causal link is identified between torsional blade dynamics and changes in ultimate load results.

  2. Dynamic stress of impeller blade of shaft extension tubular pump device based on bidirectional fluid-structure interaction

    Energy Technology Data Exchange (ETDEWEB)

    Kan, Kan; Liu, Huiwen; Yang, Chunxia [Hohai University, Nanjing (China); Zheng, Yuan [National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety, Nanjing (China); Fu, Shifeng; Zhang, Xin [Power China Huadong Engineering Corporation, Hangzhou (China)

    2017-04-15

    Current research on the stability of tubular pumps is mainly concerned with the transient hydrodynamic characteristics. However, the structural response under the influence of fluid-structure interaction hasn't been taken fully into consideration. The instability of the structure can cause vibration and cracks, which may threaten the safety of the unit. We used bidirectional fluid-structure interaction to comprehensively analyze the dynamic stress characteristics of the impeller blades of the shaft extension tubular pump device. Furthermore, dynamic stress of impeller blade of shaft extension tubular pump device was solved under different lift conditions of 0° blade angle. Based on Reynolds-average N-S equation and SST k-ω turbulence model, numerical simulation was carried out for three-dimensional unsteady incompressible turbulent flow field of the pump device whole flow passage. Meanwhile, the finite element method was used to calculate dynamic characteristics of the blade structure. The blade dynamic stress distribution was obtained on the basis of fourth strength theory. The research results indicate that the maximum blade dynamic stress appears at the joint between root of inlet side of the blade suction surface and the axis. Considering the influence of gravity, the fluctuation of the blade dynamic stress increases initially and decreases afterwards within a rotation period. In the meantime, the dynamic stress in the middle part of inlet edge presents larger relative fluctuation amplitude. Finally, a prediction method for dynamic stress distribution of tubular pump considering fluid-structure interaction and gravity effect was proposed. This method can be used in the design stage of tubular pump to predict dynamic stress distribution of the structure under different operating conditions, improve the reliability of pump impeller and analyze the impeller fatigue life.

  3. Effect of the number of blades on the dynamics of floating straight-bladed vertical axis wind turbines

    DEFF Research Database (Denmark)

    Cheng, Zhengshun; Aagaard Madsen, Helge; Gao, Zhen

    2017-01-01

    of blade number on the performance of VAWTs and dynamic behavior of floating VAWTs was comprehensively studied in a fully coupled aero-hydro-servo-elastic way. Three VAWTs with straight and parallel blades, with identical solidity and with a blade number varying from two to four, were designed using...

  4. Structural characterization of rotor blades through photogrammetry

    Science.gov (United States)

    Bernardini, Giovanni; Serafini, Jacopo; Enei, Claudio; Mattioni, Luca; Ficuciello, Corrado; Vezzari, Valerio

    2016-06-01

    This paper deals with the use of photogrammetry for the experimental identification of structural and inertial properties of helicopter rotor blades4. The identification procedure is based upon theoretical/numerical algorithms for the evaluation of mass and flexural stiffness distributions which are an extension of those proposed in the past by Larsen, whereas the torsional properties (stiffness and shear center position) are determined through the Euler-Bernoulli beam theory. The identification algorithms require the knowledge of the blade displacement field produced by known steady loads. These data are experimentally obtained through photogrammetric detection technique, which allows the identification of 3D coordinates of labeled points (markers) on the structure through the correlation of 2D digital photos. Indeed, the displacement field is simply evaluated by comparing the markers positions on the loaded configuration with those on the reference one. The proposed identification procedure, numerically and experimentally validated in the past by the authors, has been here applied to the structural characterization of two main rotor blades, designed for ultra-light helicopters. Strain gauges measurements have been used to assess the accuracy of the identified properties through natural frequencies comparison as well as to evaluate the blades damping characteristics.

  5. Design Procedure of 4-Bladed Propeller

    African Journals Online (AJOL)

    PROF. O. E. OSUAGWU

    2013-09-01

    Sep 1, 2013 ... experiments with small–scale propeller mode were made in ... experiments were used to verify the design calculations like ... extent, in their aim to satisfy a particular set of .... 5.5knots. 2. = Brake power B. P from equation 2 is calculated as follow: ..... A step by step design procedure for a 4-bladed propeller ...

  6. Designing for hot-blade cutting

    DEFF Research Database (Denmark)

    Brander, David; Bærentzen, Jakob Andreas; Clausen, Kenn

    2016-01-01

    -trivial constraints of blade-cutting in a bottom-up fashion, enabling an exploration of the unique architectural potential of this fabrication approach. The method is implemented as prototype design tools in MatLAB, C++, GhPython, and Python and demonstrated through cutting of expanded polystyrene foam design...

  7. Lightning transient analysis in wind turbine blades

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Holbøll, Joachim; Madsen, Søren Find

    2013-01-01

    The transient behavior of lightning surges in the lightning protection system of wind turbine blades has been investigated in this paper. The study is based on PSCAD models consisting of electric equivalent circuits with lumped and distributed parameters involving different lightning current...

  8. Fatigue Life of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    2010-01-01

    The present paper analyses the possibility of reducing the expected damage accumulation during tower passage by modifying the wind turbine tower design from a traditional mono-tower to a tripod. Due to a narrow stagnation zone the stress reversals and hence the damage accumulation in the blades...

  9. Parametric study of composite wind turbine blades

    DEFF Research Database (Denmark)

    Kim, Taeseong; Branner, Kim; Hansen, Anders Melchior

    2011-01-01

    In this paper an anisotropic beam element for a composite wind turbine blades is developed. Eigenvalue analysis with the new beam element is conducted in order to understand its responses associated with the wind turbine performances. From the results of natural frequencies and mode shapes...

  10. Hot Blade Cuttings for the Building Industries

    DEFF Research Database (Denmark)

    Brander, David; Bærentzen, Jakob Andreas; Evgrafov, Anton

    2016-01-01

    variability in the (economically allowed) designs - i.e., to allow them to think out of the box. To address this challenge The Danish National Advanced Technology Foundation (now InnovationsFonden) is currently supporting the BladeRunner project that involves several Danish companies and public institutions...

  11. Double-Blade Sword: Trade Surplus

    Institute of Scientific and Technical Information of China (English)

    Eva

    2007-01-01

    @@ In the famous animation Saint Saiya,the golden saint of Gemini, Saga,Left audience the deepest impression of being an angel at one side and a demon at the other.So does China's trade surplus.It is a double-blade sword.

  12. Technical progress report: Peripheral mower blade. Sixth quarter report ending 12/31/99

    Energy Technology Data Exchange (ETDEWEB)

    Darden, John A.

    2000-01-01

    Machine Tech Inc. has been assisting the author with the development of the peripheral mower blade decks. Machine Tech Inc. is still developing the batwing mower deck, which was started last fall after the completion of the mounted deck. The completion date of this program is slated for February. The wing covers and the center section of the batwing have been completed, the frame and drive-lines are now under development. Information from the nineteen-foot bat-wing deck prototype that they have been testing is now being used in the development of a more acceptable bat-wing mower. This unit will be able to maintain the same peripheral mower benefits, but will be much lighter and easier to pull requiring less fuel and damage to highway right of ways in soft areas. The mounted deck has been completed and is in the pilot stage with reports yet to be compiled. Machine Tech Inc. has also worked in an agricultural deck which is closely related to the mounted peripheral mower deck developed for the highway right of way. This will be one more outlet for the peripheral mower machines into the hands of the public.

  13. Separated Pitch Control at Tip: Innovative Blade Design Explorations for Large MW Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Ranjeet Agarwala

    2015-01-01

    Full Text Available This paper focuses on the deployment and evaluation of a separated pitch control at blade tip (SePCaT control strategy for large megawatt (MW wind turbine blade and explorations of innovative blade designs as a result of such deployment. SePCaT configurations varied from five to thirty percent of the blade length in 5 percentage increments (SePCaT5, SePCaT10, SePCaT15, SePCaT20, SePCaT25, and SePCaT30 are evaluated by comparing them to aerodynamical responses of the traditional blade. For low, moderate, high, and extreme wind speed variations treated as 10, 20, 30, and 40 percent of reference wind speeds, rotor power abatement in region 3 of the wind speed power curve is realized by feathering full length blade by 6, 9, 12, and 14 degrees, respectively. Feathering SePCaT30, SePCaT25, SePCaT20, and SePCaT15 by 14, 16, 26, and 30 degrees, respectively, achieves the same power abatement results when compared to traditional blade at low wind speeds. Feathering SePCaT30, SePCaT25, and SePCaT20 by 18, 26, and 30 degrees on the other hand has the same effect at high wind speeds. SePCaT30 feathered to 26 and 30 degrees has the same abatement effects when compared to traditional blade at high and extreme wind speeds.

  14. Intermetallic blades for fabric cutting. CRADA final report

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Blue, C.A.; Sklad, S. [Oak Ridge National Lab., TN (United States); Shih, H.R. [Jackson State Univ., MS (United States); Off, J.W.A. [Textile/Clothing Technology Corp., Cary, NC (United States)

    1998-08-01

    This report describes the evaluation of nickel- and iron-aluminide blades for cutting fabric as opposed to conventional steel blades. The aluminides were selected as blade material because of their extremely high work-hardening rate and the possibility of forming aluminum oxide on the surface to further enhance the wear resistance. Unlike steel blades, they do not require heat treating to become strong. A testing facility using an Eastman cutter was designed and built at the Oak Ridge National Laboratory (ORNL) for testing of blades. Denim fabric supplied by Levi Strauss was used. For lack of sufficient fabric, heavy paper was also used. Extensive testing revealed that there were several issues in getting the true comparison between various blades. The most important issue was the consistent sharpening of the blade edge. With all of the effort and precautions, identical edges could not be put on the blades of all the different materials. The second issue was the limited availability of fabric to evaluate the end-of-life limit for the blade edges. Two nickel- and three iron-aluminide compositions were evaluated. Under test conditions, the iron-aluminide alloy (PM-60), based on FeAl, was found to outperform other aluminides and the steel blade. Based on the data presented in this report, the authors recommend that additional testing be carried out on both the steel and aluminide blades to determine the number of times each blade can be sharpened prior to its replacement. However, the recommended testing needs to be conducted on blades for which the identical cutting edges and sharpening are incorporated. They further recommend that if the iron-aluminide blade is truly superior, a cost analysis be performed to determine its commercial feasibility. The best aluminide blades should be tested by commercial textile companies.

  15. Intermetallic blades for fabric cutting. CRADA final report

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Blue, C.A.; Sklad, S. [Oak Ridge National Lab., TN (United States); Shih, H.R. [Jackson State Univ., MS (United States); Off, J.W.A. [Textile/Clothing Technology Corp., Cary, NC (United States)

    1998-08-01

    This report describes the evaluation of nickel- and iron-aluminide blades for cutting fabric as opposed to conventional steel blades. The aluminides were selected as blade material because of their extremely high work-hardening rate and the possibility of forming aluminum oxide on the surface to further enhance the wear resistance. Unlike steel blades, they do not require heat treating to become strong. A testing facility using an Eastman cutter was designed and built at the Oak Ridge National Laboratory (ORNL) for testing of blades. Denim fabric supplied by Levi Strauss was used. For lack of sufficient fabric, heavy paper was also used. Extensive testing revealed that there were several issues in getting the true comparison between various blades. The most important issue was the consistent sharpening of the blade edge. With all of the effort and precautions, identical edges could not be put on the blades of all the different materials. The second issue was the limited availability of fabric to evaluate the end-of-life limit for the blade edges. Two nickel- and three iron-aluminide compositions were evaluated. Under test conditions, the iron-aluminide alloy (PM-60), based on FeAl, was found to outperform other aluminides and the steel blade. Based on the data presented in this report, the authors recommend that additional testing be carried out on both the steel and aluminide blades to determine the number of times each blade can be sharpened prior to its replacement. However, the recommended testing needs to be conducted on blades for which the identical cutting edges and sharpening are incorporated. They further recommend that if the iron-aluminide blade is truly superior, a cost analysis be performed to determine its commercial feasibility. The best aluminide blades should be tested by commercial textile companies.

  16. Numerical investigation of the effect of number of blades on centrifugal pump performance

    Science.gov (United States)

    Kocaaslan, O.; Ozgoren, M.; Babayigit, O.; Aksoy, M. H.

    2017-07-01

    In this study, the flow structure in a centrifugal pump was numerically investigated for the different blade numbers in the impeller between 5 and 9. The pump used in the study is a single-stage horizontal shafted centrifugal pump. The original pump impeller was designed as 7 blades for the parameters of flow rate Q=100 mł/h, head Hm=180 kPa and revolution n=1480 rpm. First, models of impellers with the different blade numbers between 5 and 9 and the volute section of the centrifugal pump were separately drawn using Solidworks software. Later, grid structures were generated on the flow volume of the pump. Last, the flow analyses were performed and the flow characteristics under different operational conditions were determined numerically. In the numerical analyses, k-ɛ turbulence model and standard wall functions were used to solve turbulent flow. Balance holes and surface roughness, which adversely affect the hydraulic efficiency of pumps, were also considered. The obtained results of the analyses show that the hydraulic torque and head values have increased with the application of higher number of the impeller blades. For the impellers with 5 and 9 blades on the design flow rate of 100 mł/h (Q/Qd=1), the hydraulic torque and head were found 49/59.1 Nm and 153.1/184.4 kPa, respectively. Subsequently the hydraulic efficiencies of each pump were calculated. As a result, the highest hydraulic efficiency on the design flow rate was calculated as 54.16% for the pump impeller having 8 blades.

  17. Ion beam analysis of gas turbine blades: evaluation of refurbishment quality

    Indian Academy of Sciences (India)

    O Kakuee; V Fathollahi; P Oliaiy; D Agha-Aligol; M Lamehi-Rachti

    2015-04-01

    Refurbishment of hot components of gas turbines damaged in the harsh working environments is necessary to increase their lifetime. Scanning proton microscopy was employed to evaluate the quality of refurbishment process of gas turbine blades. Distribution patterns of different elements were observed in the polished cross-sections of turbine blade samples by proton microbeam. In the cross-sections of refurbished and used samples, distinct regions were identified corresponding to the base superalloy, original protection layer and applied coating for refurbishment. The elemental composition of each of these regions was measured by Micro-PIXE analysis. Inhomogeneous and high content of Si as well as undesired light elements were observed in the cross-sections of refurbished samples, indicating imperfections in the refurbishment process.

  18. Probability strength design of steam turbine blade and sensitivity analysis with respect to random parameters based on response surface method

    Institute of Scientific and Technical Information of China (English)

    Wei DUAN

    2008-01-01

    Many stochastic parameters have an effect on the reliability of a steam turbine blade during practical operation. To improve the reliability of blade design, it is necessary to take these stochastic parameters into account. An equal cross-section blade is investigated and a finite element model is built parametrically. Geometrical parameters, material parameters and load parameters of the blade are considered as input random variables while the maximum deflection and maximum equivalent stress are output random variables. Analysis file of the blade is compiled by deterministic finite element method and applied to be loop file to create sample points. A quadratic polynomial with cross terms is chosen to regress these samples by step-forward regression method and employed as a surrogate of numerical solver to drastically reduce the number of solvers call. Then, Monte Carlo method is used to obtain the statistical characteristics and cumulative distribution function of the maximum deflection and maximum equivalent stress of the blade. Probability sensitivity analysis, which combines the slope of the gradient and the width of the scatter range of the random input variables, is applied to evaluate how much the output parameters are influenced by the random input para-meters. The scatter plots of structural responses with respect to the random input variables are illustrated to analyze how to change the input random variables to improve the reliability of the blade. The results show that combination of the finite element method, the response surface method and Monte Carlo method is an ideal way for the reliability analysis and probability strength design of the blade.

  19. Resonant vibration control of three-bladed wind turbine rotors

    DEFF Research Database (Denmark)

    Krenk, Steen; Svendsen, Martin Nymann; Høgsberg, Jan Becker

    2012-01-01

    Rotors with blades, as in wind turbines, are prone to vibrations due to the flexibility of the blades and the support. In the present paper a theory is developed for active control of a combined set of vibration modes in three-bladed rotors. The control system consists of identical collocated...... to influence of other nonresonant modes. The efficiency of the method isdemonstrated byapplication to a rotor with 42 m blades, where the sensor/actuator system is implemented in the form of an axial extensible strut near the root of each blade. The load is provided by a simple but fully threedimensional...

  20. Performance prediction for windmills with linkage-guided blades

    Energy Technology Data Exchange (ETDEWEB)

    Nahas, M.N.; Akyurt, M. (Mechanical Engineering Dept., King Abdul Aziz Univ., Jeddah (SA))

    1992-01-01

    Three windmills with linkage-guided blades that were previously described by the authors are future studied to predict their performance. The present paper concentrates on the guiding mechanisms of the active power producing surfaces (or blades) and on the output torque. Also investigated here is the effect of the orientation of these blades with respect to their guiding links. The fluctuation in the output torque of one-blade windmills has led to the investigation of the output torque that can be obtained from three-bladed machines. These latter windmills are found to reduce the fluctuation in the output torque considerably. Areas for further improvement are discussed.

  1. Blade Bearing Friction Estimation of Operating Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Pedersen, Bo Juul; Kirkegaard, Poul Henning

    2012-01-01

    Blade root bearing on a wind turbine (WTG) enables pitching of blades for power control and rotor braking and is a WTG critical component. As the size of modern WTGs is constantly increasing, this leads to relatively less rigid bearings, more sensitive to deformations, thus WTG operational...... reliability can be increased by continuous monitoring of blade bearing. High blade bearing friction is undesirable, as it may be associated with excessive heating of the surfaces, damage and/or inefficient operation. Thus, continuous observation of bearing friction level is crucial for blade bearing health...

  2. Optimizing parameters of GTU cycle and design values of air-gas channel in a gas turbine with cooled nozzle and rotor blades

    Science.gov (United States)

    Kler, A. M.; Zakharov, Yu. B.

    2012-09-01

    The authors have formulated the problem of joint optimization of pressure and temperature of combustion products before gas turbine, profiles of nozzle and rotor blades of gas turbine, and cooling air flow rates through nozzle and rotor blades. The article offers an original approach to optimization of profiles of gas turbine blades where the optimized profiles are presented as linear combinations of preliminarily formed basic profiles. The given examples relate to optimization of the gas turbine unit on the criterion of power efficiency at preliminary heat removal from air flows supplied for the air-gas channel cooling and without such removal.

  3. Effect of a culture-based screening algorithm on tuberculosis incidence in immigrants and refugees bound for the United States: a population-based cross-sectional study.

    Science.gov (United States)

    Liu, Yecai; Posey, Drew L; Cetron, Martin S; Painter, John A

    2015-03-17

    Before 2007, immigrants and refugees bound for the United States were screened for tuberculosis (TB) by a smear-based algorithm that could not diagnose smear-negative/culture-positive TB. In 2007, the Centers for Disease Control and Prevention implemented a culture-based algorithm. To evaluate the effect of the culture-based algorithm on preventing the importation of TB to the United States by immigrants and refugees from foreign countries. Population-based, cross-sectional study. Panel physician sites for overseas medical examination. Immigrants and refugees with TB. Comparison of the increase of smear-negative/culture-positive TB cases diagnosed overseas among immigrants and refugees by the culture-based algorithm with the decline of reported cases among foreign-born persons within 1 year after arrival in the United States from 2007 to 2012. Of the 3 212 421 arrivals of immigrants and refugees from 2007 to 2012, a total of 1 650 961 (51.4%) were screened by the smear-based algorithm and 1 561 460 (48.6%) were screened by the culture-based algorithm. Among the 4032 TB cases diagnosed by the culture-based algorithm, 2195 (54.4%) were smear-negative/culture-positive. Before implementation (2002 to 2006), the annual number of reported cases among foreign-born persons within 1 year after arrival was relatively constant (range, 1424 to 1626 cases; mean, 1504 cases) but decreased from 1511 to 940 cases during implementation (2007 to 2012). During the same period, the annual number of smear-negative/culture-positive TB cases diagnosed overseas among immigrants and refugees bound for the United States by the culture-based algorithm increased from 4 to 629. This analysis did not control for the decline in new arrivals of nonimmigrant visitors to the United States and the decrease of incidence of TB in their countries of origin. Implementation of the culture-based algorithm may have substantially reduced the incidence of TB among newly arrived, foreign-born persons in

  4. Development of Standard Approach for Sickle Blade Manufacturing

    Directory of Open Access Journals (Sweden)

    M. N. A. Noordin

    2016-10-01

    Full Text Available The sickle blade used in the motorised palm cutter known as “CANTAS” provides fast, easy and safe pruning and harvesting for those hard to reach applications. Jariz Technologies Company is experiencing problem in the consistency of sickle blade which was supplied by various blade manufacturers. Identifying the proper blade material with a certain hardness value would produce a consistent as well as long lasting sickle blade. A Standard Operating Procedure (SOP in the manufacturing of the sickle blades was suggested to ensure a consistent blade. From this study, the optimum temperature for hardening and tempering of SUP 9 had been identified as 850 °C for hardening and 480 °C for tempering. The final hardness after heat treatment for SUP 9 was around 55HRC.

  5. Plowing of granular surface by a vertical blade

    Science.gov (United States)

    Judge, Vachitar Singh; Dressaire, Emilie; Sauret, Alban

    2016-11-01

    The interaction of a blade with a layer of fluid is an important industrial problem involved in coating of substrates, removing of snow, plowing the fields for agriculture. Most experimental and theoretical work has focused on the drag and lift forces on plowing blade as it is dragged on a granular surface or studying the flow of the fluid while plowing. However the study of deformation of a granular surface by a vertical plow blade has received less attention, despite significant practical and fundamental implications. In this study, we investigate experimentally the behavior of a granular substrate as a vertical plow blade of finite width is translated at constant speed. The vertical blade directs the granular material outward and sand piles form on either sides. We characterize the dynamics of plowing by measuring and rationalizing the influence of the width of the vertical plow blade, the height of the plow blade, and the depth granular substrate.

  6. Advances in wind turbine blade design and materials

    DEFF Research Database (Denmark)

    Wind energy is gaining critical ground in the area of renewable energy, with wind energy being predicted to provide up to 8% of the world’s consumption of electricity by 2021. Advances in wind turbine blade design and materials reviews the design and functionality of wind turbine rotor blades...... of wind turbine blades. The final part of the book describes advances in wind turbine blade materials, development and testing, including biobased composites, surface protection and coatings, structural performance testing and the design, manufacture and testing of small wind turbine blades. Advances...... in wind turbine blade design and materials offers a comprehensive review of the recent advances and challenges encountered in wind turbine blade materials and design, and will provide an invaluable reference for researchers and innovators in the field of wind energy production, including materials...

  7. Study on Aerodynamic Design Optimization of Turbomachinery Blades

    Institute of Scientific and Technical Information of China (English)

    Naixing CHEN; Hongwu ZHANG; Weiguang HUANG; Yanji XU

    2005-01-01

    This paper describes the study on aerodynamics design optimization of turbomachinery blading developed by the authors at the Institute of Engineering Thermophysics, Chinese Academy of Sciences, during the recent few years. The present paper describes the aspects mainly on how to use a rapid approach of profiling a 3D blading and of grid generation for computation, a fast and accurate viscous computation method and an appropriate optimization methodology_ including a blade parameterization algorithm to optimize turbomachinery blading aerodynamically. Any blade configuration can be expressed by three curves, they are the camber lines, the thickness distributions and the radial stacking line, and then the blade geometry can be easily parameterized by a number of parameters with three polynomials. A gradient-based parameterization analytical method and a response surface method were applied herein for blade optimization. It was found that the optimization process provides reliable design for turbomachinery with reasonable computing time.

  8. Rotor blade full-scale fatigue testing technology and research

    DEFF Research Database (Denmark)

    Nielsen, Per Hørlyk; Berring, Peter; Pavese, Christian

    Full scale fatigue test is an important part of the development and design of wind turbine blades. Testing is also needed for the approval of the blades in order for them to be used on large wind turbines. However, usually only one prototype blade is tested. Fatigue test of wind turbine blades...... was started in the beginning of the 1980´s and has been further developed since then. Structures in composite materials are generally difficult and time consuming to test for fatigue resistance. Therefore, several methods for testing of blades have been developed and exist today. These methods...... will be presented in this report giving the blade test facility operator a guide to choose the method that best fit the needs and economic constraints. The state of the art method is currently dual axis mass resonance, where the purpose of the test is to emulate the loads the blades encounter in operation....

  9. Comparison of linear and non-linear blade model predictions in Bladed to measurement data from GE 6MW wind turbine

    Science.gov (United States)

    Collier, W.; Milian Sanz, J.

    2016-09-01

    The length and flexibility of wind turbine blades are increasing over time. Typically, the dynamic response of the blades is analysed using linear models of blade deflection, enhanced by various ad-hoc non-linear correction models. For blades undergoing large deflections, the small deflection assumption inherent to linear models becomes less valid. It has previously been demonstrated that linear and nonlinear blade models can show significantly different blade response, particularly for blade torsional deflection, leading to load prediction differences. There is a need to evaluate how load predictions from these two approaches compare to measurement data from the field. In this paper, time domain simulations in turbulent wind are carried out using the aero-elastic code Bladed with linear and non-linear blade deflection models. The turbine blade load and deflection simulation results are compared to measurement data from an onshore prototype of the GE 6MW Haliade turbine, which features 73.5m long LM blades. Both linear and non-linear blade models show a good match to measurement turbine load and blade deflections. Only the blade loads differ significantly between the two models, with other turbine loads not strongly affected. The non-linear blade model gives a better match to the measured blade root flapwise damage equivalent load, suggesting that the flapwise dynamic behaviour is better captured by the non-linear blade model. Conversely, the linear blade model shows a better match to measurements in some areas such as blade edgewise damage equivalent load.

  10. Comparison of Computational and Experimental Results for a Transonic Variable-speed Power-Turbine Blade Operating with Low Inlet Turbulence Levels

    Science.gov (United States)

    Booth, David T.; Flegel, Ashlie B.

    2015-01-01

    A computational assessment of the aerodynamic performance of the midspan section of a variable-speed power-turbine blade is described. The computation comprises a periodic single blade that represents the 2-D Midspan section VSPT blade that was tested in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility. A commercial, off-the-shelf (COTS) software package, Pointwise and CFD++, was used for the grid generation and RANS and URANS computations. The CFD code, which offers flexibility in terms of turbulence and transition modeling options, was assessed in terms of blade loading, loss, and turning against test data from the transonic tunnel. Simulations were assessed at positive and negative incidence angles that represent the turbine cruise and take-off design conditions. The results indicate that the secondary flow induced at the positive incidence cruise condition results in a highly loaded case and transitional flow on the blade is observed. The negative incidence take-off condition is unloaded and the flow is very two-dimensional. The computational results demonstrate the predictive capability of the gridding technique and COTS software for a linear transonic turbine blade cascade with large incidence angle variation.

  11. Large-scale Wind Turbine Blade Redesign Based on Reverse Engineering%大型风能发电机组叶片反求再设计

    Institute of Scientific and Technical Information of China (English)

    陶庆; 孙文磊

    2015-01-01

    叶片的外形设计和翼型的选择等都能影响风机性能和产能效率。提出一种大型风能发电机组叶片反求再设计的原理和方法,通过对大型风能发电机组叶片反求测量、大型风能发电机组叶片逆向CAD建模,寻找几何特征,探索制约叶片形状的基本因素,确定叶片截面参数计算公式,利用所开发的叶片翼型自动生成系统,完成了叶片的再设计,并得到了实际应用。%The large⁃scale wind turbine blade contour design and the choice of wing section affect the wind turbine performance and energy efficiency. A redesign principle and method for large⁃scale wind turbine blade was presented which was based on the analy⁃sis of blade CAD model from reverse engineering, looking for geometric features, exploring basic constraint factors on blade shape, and determining parameters of blade cross section calculation formula. Blade design was completed using this self⁃developed blade aerofoil automatic generation system. The results show that the redesign meets the production requirements.

  12. Wind Turbine Blade Nondestructive Testing with a Transportable Radiography System

    Directory of Open Access Journals (Sweden)

    J. G. Fantidis

    2011-01-01

    Full Text Available Wind turbines are becoming widely used as they are an environmentally friendly way for energy production without emissions; however, they are exposed to a corrosive environment. In addition, as wind turbines typically are the tallest structures in the surrounding area of a wind farm, it is expected that they will attract direct lightning strikes several times during their operating life. The purpose of this paper is to show that the radiography with a transportable unit is a solution to find defects in the wind turbine blade and reduce the cost of inspection. A transportable neutron radiography system, incorporating an Sb–Be source, has been simulated using the MCNPX code. The simulated system has a wide range of radiography parameters.

  13. TOPOLOGY AND VORTEX STRUCTURES OF A CURVING TURBINE CASCADE WITH TIP CLEARANCE ( Ⅰ )- EXPERIMENTAL MODEL AND TOPOLOGICAL FLOW PATTERNS ON BOTH ENDWALLS AND BLADE SURFACES

    Institute of Scientific and Technical Information of China (English)

    杨庆海; 黄洪雁; 韩万今

    2002-01-01

    By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in the transverse section, and by appling topology theory, the structures on both endwalls and blade surfaces were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex and leads the secondary vortex to change from close separation to open separation,while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.

  14. 新目标(八年级下)Unit 2 What should I do?Section B教学设计

    Institute of Scientific and Technical Information of China (English)

    王红

    2009-01-01

    一、教学分析(一)教学内容本课为一节听读课,教学内容为Go for it!(八年级下)Unit 2 What should I do?Section B 2a,2b,3a,其内容是围绕朋友这个话题展开的,要求学生通过听力和阅读了解别人在生活中关于朋友的困惑。听力中所呈现的是Erin想通过新颖的穿着体现自己独特的个性,

  15. Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades

    OpenAIRE

    2007-01-01

    This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP) neural network and genetic algorithm (GA), the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pres...

  16. Derivation of airfoil characteristics for the LM 19.1 blade based on 3D CFD rotor calculations

    Energy Technology Data Exchange (ETDEWEB)

    Bak, C.; Soerensen, N.N.; Madsen, H.A. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    Airfoil characteristics for the LM 19.1 blade are derived from 3D CFD computations on a full-scale 41-m rotor. Based on 3D CFD the force distributions on the blades are determined, from which airfoil characteristics are derived using the momentum theory. The final airfoil characteristics are constructed using both wind tunnel measurements and 3D CFD. Compared to 2D wind tunnel measurements they show a low lift in stall for the airfoil sections at the tip. At the airfoil sections at the inner part of the blade, they show a high lift in stall. At about 60% radius the lift agrees well to 2D wind tunnel measurements. Aero-elastic calculations using the final airfoil characteristics show good agreement to measured power and flap moments. Furthermore, a fatigue load analysis shows a reduction of up to 15% of the load compared to commonly used data. (au)

  17. Non-steady dynamics of atmospheric turbulence interaction with wind turbine loadings through blade-boundary-layer-resolved CFD

    Science.gov (United States)

    Vijayakumar, Ganesh

    Modern commercial megawatt-scale wind turbines occupy the lower 15-20% of the atmospheric boundary layer (ABL), the atmospheric surface layer (ASL). The current trend of increasing wind turbine diameter and hub height increases the interaction of the wind turbines with the upper ASL which contains spatio-temporal velocity variations over a wide range of length and time scales. Our interest is the interaction of the wind turbine with the energetic integral-scale eddies, since these cause the largest temporal variations in blade loadings. The rotation of a wind turbine blade through the ABL causes fluctuations in the local velocity magnitude and angle of attack at different sections along the blade. The blade boundary layer responds to these fluctuations and in turn causes temporal transients in local sectional loads and integrated blade and shaft bending moments. While the integral scales of the atmospheric boundary layer are ˜ O(10--100m) in the horizontal with advection time scales of order tens of seconds, the viscous surface layer of the blade boundary layer is ˜ O(10 -- 100 mum) with time scales of order milliseconds. Thus, the response of wind turbine blade loadings to atmospheric turbulence is the result of the interaction between two turbulence dynamical systems at extremely disparate ranges of length and time scales. A deeper understanding of this interaction can impact future approaches to improve the reliability of wind turbines in wind farms, and can underlie future improvements. My thesis centers on the development of a computational framework to simulate the interaction between the atmospheric and wind turbine blade turbulence dynamical systems using a two step one-way coupled approach. Pseudo-spectral large eddy simulation (LES) is used to generate a true (equilibrium) atmospheric boundary layer over a flat land with specified surface roughness and heating consistent with the stability state of the daytime lower troposphere. Using the data from the

  18. Deflection estimation of a wind turbine blade using FBG sensors embedded in the blade bonding line

    Science.gov (United States)

    Kim, Sang-Woo; Kang, Woo-Ram; Jeong, Min-Soo; Lee, In; Kwon, Il-Bum

    2013-12-01

    Estimating the deflection of flexible composite wind turbine blades is very important to prevent the blades from hitting the tower. Several researchers have used fiber Bragg grating (FBG) sensors—a type of optical fiber sensor (OFS)—to monitor the structural behavior of the blades. They can be installed on the surface and/or embedded in the interior of composites. However, the typical installation positions of OFSs present several problems, including delamination of sensing probes and a higher risk of fiber breakage during installation. In this study, we proposed using the bonding line between the shear web and spar cap as a new installation position of embedded OFSs for estimating the deflection of the blades. Laboratory coupon tests were undertaken preliminarily to confirm the strain measuring capability of embedded FBG sensors in adhesive layers, and the obtained values were verified by comparison with results obtained by electrical strain gauges and finite element analysis. We performed static loading tests on a 100 kW composite wind turbine blade to evaluate its deflections using embedded FBG sensors positioned in the bonding line. The deflections were estimated by classical beam theory considering a rigid body rotation near the tip of the blade. The evaluated tip deflections closely matched those measured by a linear variable differential transformer. Therefore, we verified the capability of embedded FBG sensors for evaluating the deflections of wind turbine blades. In addition, we confirmed that the bonding line between the shear web and spar cap is a practical location to embed the FBG sensors.

  19. Inclusion of a simple dynamic inflow model in the blade element momentum theory for wind turbine application

    Directory of Open Access Journals (Sweden)

    Xiaomin Chen, Ramesh K. Agarwal

    2014-01-01

    Full Text Available It is well established that the power generated by a Horizontal-Axis Wind Turbine (HAWT is a function of the number of blades B, the tip speed ratio (blade tip speed/wind free-stream velocity and the lift to drag ratio (CL /CD of the airfoil sections of the blade. The previous studies have shown that Blade Element Momentum (BEM theory is capable of evaluating the steady-state performance of wind turbines, in particular it can provide a reasonably good estimate of generated power at a given wind speed. However in more realistic applications, wind turbine operating conditions change from time to time due to variations in wind velocity and the aerodynamic forces change to new steady-state values after the wake settles to a new equilibrium whenever changes in operating conditions occur. The goal of this paper is to modify the quasi-steady BEM theory by including a simple dynamic inflow model to capture the unsteady behavior of wind turbines on a larger time scale. The output power of the wind turbines is calculated using the improved BEM method incorporating the inflow model. The computations are performed for the original NREL Phase II and Phase III turbines and the Risoe turbine all employing the S809 airfoil section for the turbine blades. It is shown by a simple example that the improved BEM theory is capable of evaluating the wind turbine performance in practical situations where operating conditions often vary in time.

  20. Numerical Simulation on Effects of Pressure Distribution of Wind Turbine Blade with a Tip Vane

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Wen; JIA Rui-Bo; WU Ke-Qi

    2007-01-01

    It is important to study the pressure distribution on the blade and in the adjacent area while searching the power augmentation theory with adding a tip vane to the wind turbine. This paper shows the CFD simulation relationship of the pressure distribution on the rotor blade and in the adjacent area, after calculating the pressure of the different chordwise and spanwise point on the blade with the tip vane-V(8.8×8) and without the tip vane under tip speed ratio λ 4.5. Combining the isobaric section figure in certain location, it can be seen that the tip vane improve the pressure difference between pressure and suction surface. The most influenced zone is found and these can further display the power augmentation theory of the wind turbine using the tip vane. The simulation calculation was based on N-S equations. 3-D, steady, implicit solver was chosen. Turbulence model was k- ω SST. Discretization cheme is SECOND ORDER UPWIND. Pressure-velocity coupling was a typical SIMPLE scheme. In the whole grid system, two-divided grid formation was adopted, that is, inner region and outer region. Inner region including rectangular solid blade and neighboring, outer region is semi-cylinder. There were together 720,000 nodes with tetra-prism unstructured mesh.

  1. Composite Structural Analysis of Flat-Back Shaped Blade for Multi-MW Class Wind Turbine

    Science.gov (United States)

    Kim, Soo-Hyun; Bang, Hyung-Joon; Shin, Hyung-Ki; Jang, Moon-Seok

    2014-06-01

    This paper provides an overview of failure mode estimation based on 3D structural finite element (FE) analysis of the flat-back shaped wind turbine blade. Buckling stability, fiber failure (FF), and inter-fiber failure (IFF) analyses were performed to account for delamination or matrix failure of composite materials and to predict the realistic behavior of the entire blade region. Puck's fracture criteria were used for IFF evaluation. Blade design loads applicable to multi-megawatt (MW) wind turbine systems were calculated according to the Germanischer Lloyd (GL) guideline and the International Electrotechnical Commission (IEC) 61400-1 standard, under Class IIA wind conditions. After the post-processing of final load results, a number of principal load cases were selected and converted into applied forces at the each section along the blade's radius of the FE model. Nonlinear static analyses were performed for laminate failure, FF, and IFF check. For buckling stability, linear eigenvalue analysis was performed. As a result, we were able to estimate the failure mode and locate the major weak point.

  2. Near wall flow parameters in the blade end-wall corner region

    Science.gov (United States)

    Bhargava, R. K.; Raj, R.

    The effects of secondary end-wall corner flows on near wall flow parameters in turbomachinary are studied. Important near wall flow parameters such as the wall shear stress vector, the mean wall pressure, the wall pressure fluctuations, and the correlation of the wall pressure fluctuation with the velocity fluctuation in three-dimensional turbulent flows are first experimentally investigated. The blade end-wall corner region is simulated by mounting airfoil section of symmetric blades on both sides of the flat plate with semicircular leading edge. Observed changes in the maximum values of the wall shear stress and its location from the corner line could be associated with the streching and attenuation of the horseshoe vortex. The values of wall pressure fluctuation intensity in the blade end-wall corner region are found to be influenced by the changes of the strength of the horseshoe vortex. The correlation of the wall pressure fluctuation with the velocity fluctuation indicated higher values of correlation coefficient in the inner region as compared to the outer region of the shear layer. The values of wall pressure-velocity correlation coefficient in the blade end-wall corner region also decrease in the streamwise direction while increasing in the presence of favorable and adverse pressure gradients.

  3. An aerodynamic study on flexed blades for VAWT applications

    Science.gov (United States)

    Micallef, Daniel; Farrugia, Russell; Sant, Tonio; Mollicone, Pierluigi

    2014-12-01

    There is renewed interest in aerodynamics research of VAWT rotors. Lift type, Darrieus designs sometimes use flexed blades to have an 'egg-beater shape' with an optimum Troposkien geometry to minimize the structural stress on the blades. While straight bladed VAWTs have been investigated in depth through both measurements and numerical modelling, the aerodynamics of flexed blades has not been researched with the same level of detail. Two major effects may have a substantial impact on blade performance. First, flexing at the equator causes relatively strong trailing vorticity to be released. Secondly, the blade performance at each station along the blade is influenced by self-induced velocities due to bound vorticity. The latter is not present in a straight bladed configuration. The aim of this research is to investigate these effects in relation to an innovative 4kW wind turbine concept being developed in collaboration with industry known as a self-adjusting VAWT (or SATVAWT). The approach used in this study is based on experimental and numerical work. A lifting line free-wake vortex model was developed. Wind tunnel power and hot-wire velocity measurements were performed on a scaled down, 60cm high, three bladed model in a closed wind tunnel. Results show a substantial axial wake induction at the equator resulting in a lower power generation at this position. This induction increases with increasing degree of flexure. The self-induced velocities caused by blade bound vorticity at a particular station was found to be relatively small.

  4. Tip cap for a turbine rotor blade

    Science.gov (United States)

    Kimmel, Keith D

    2014-03-25

    A turbine rotor blade with a spar and shell construction, and a tip cap that includes a row of lugs extending from a bottom side that form dovetail grooves that engage with similar shaped lugs and grooves on a tip end of the spar to secure the tip cap to the spar against radial displacement. The lug on the trailing edge end of the tip cap is aligned perpendicular to a chordwise line of the blade in the trailing edge region in order to minimize stress due to the lugs wanting to bend under high centrifugal loads. A two piece tip cap with lugs at different angles will reduce the bending stress even more.

  5. Control of LP Turbine Rotor Blade Underloading Using Stator Blade Compound Lean at Root

    Institute of Scientific and Technical Information of China (English)

    PiotrLampart

    2000-01-01

    Due to a large gradient of reaction,LP rotor blades remain underloaded at the root over some range of volumetric flow rates.An interesting design to control the flow through the root passage of the overloaded stator and underloaded moving blade row is compound lean at the root of stator blades.The paper describes results of numerical investigations from a 3D NS solver FlowER conducted for several configurations of stator blade compund lean.The computations are carried out for a wide range of volumetric flow rates.accounting for the nominal operating regime as well as low and high load.It is found that compund lean induces additional blade force.streamwise curature and redistribution of flow parameters in the stage,including pressure and mass flow rate spanwise that can improve the flow conditions in both the stator and the rotor.The obtained efficiency improvements depend greatly on the flow regime,with the highest gains in the region of low load.

  6. Effect of blade pitch angle on aerodynamic performance of straight-bladed vertical axis wind turbine

    Institute of Scientific and Technical Information of China (English)

    张立勋; 梁迎彬; 刘小红; 郭健

    2014-01-01

    Wind energy is one of the most promising renewable energy sources, straight-bladed vertical axis wind turbine (S-VAWT) appears to be particularly promising for the shortage of fossil fuel reserves owing to its distinct advantages, but suffers from poor self-starting and low power coefficient. Variable-pitch method was recognized as an attractive solution to performance improvement, thus majority efforts had been devoted into blade pitch angle effect on aerodynamic performance. Taken into account the local flow field of S-VAWT, mathematical model was built to analyze the relationship between power outputs and pitch angle. Numerical simulations on static and dynamic performances of blade were carried out and optimized pitch angle along the rotor were presented. Comparative analyses of fixed pitch and variable-pitch S-VAWT were conducted, and a considerable improvement of the performance was obtained by the optimized blade pitch angle, in particular, a relative increase of the power coefficient by more than 19.3%. It is further demonstrated that the self-starting is greatly improved with the optimized blade pitch angle.

  7. Blade pitch control of straight-bladed vertical axis wind turbine

    Institute of Scientific and Technical Information of China (English)

    梁迎彬; 张立勋; 李二肖; 张凤月

    2016-01-01

    Collective pitch control and individual pitch control algorithms were present for straight-bladed vertical axis wind turbine to improve the self-starting capacity. Comparative analysis of straight-bladed vertical axis wind turbine(SB-VAWT) with or without pitch control was conducted from the aspects of aerodynamic force, flow structure and power coefficient. The computational fluid dynamics (CFD) prediction results show a significant increase in power coefficient for SB-VAWT with pitch control. According to the aerodynamic forces and total torque coefficient obtained at various tip speed ratios (TSRs), the results indicate that the blade pitch method can increase the power output and decrease the deformation of blade;especially, the total torque coefficient of blade pitch control at TSR 1.5 is about 2.5 times larger than that of fixed pitch case. Furthermore, experiment was carried out to verify the feasibility of pitch control methods. The results show that the present collective pitch control and individual pitch control methods can improve the self-starting capacity of SB-VAWT, and the former is much better and its proper operating TSRs ranges from 0.4 to 0.6.

  8. Photoacoustic microscopy of ceramic turbine blades

    Science.gov (United States)

    Khandelwal, P. K.; Kinnick, R. R.; Heitman, P. W.

    1985-01-01

    Scanning photoacoustic microscopy (SPAM) is evaluated as a nondestructive technique for the detection of both surface and subsurface flaws in polycrystalline ceramics, such as those currently under consideration for the high temperature components of small vehicular and industrial gas turbine engines; the fracture strength of these brittle materials is controlled by small, 25-200 micron flaws. Attention is given to the correlation of SPAM-detected flaws with actual, fracture-controlling flaws in ceramic turbine blades.

  9. Turbine blade with tuned damping structure

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Christian X.; Messmann, Stephen J.

    2015-09-01

    A turbine blade is provided comprising: a root; an airfoil comprising an external wall extending radially from the root and having a radially outermost portion; and a damping structure. The external wall may comprise first and second side walls joined together to define an inner cavity of the airfoil. The damping structure may be positioned within the airfoil inner cavity and coupled to the airfoil so as to define a tuned mass damper.

  10. Advancing Blade Concept (ABC) Technology Demonstrator

    Science.gov (United States)

    1981-04-01

    id5I:~ W Ith coIle t ior, I: a’ tlet- Liou tesýts, t~he 1total blades were iisa edad he ,! l01 ;wnq1 sys"tem11 tests and operationlal checks...Equipment The data acquisition system recording media was a Bell and Howell Model MARS-2000 14-track airborne analog magnetic tape recorder. The magnetic

  11. Subjective evaluation of helicopter blade slap noise

    Science.gov (United States)

    Galloway, W. J.

    1978-01-01

    Several methods for adjusting EPNL to account for its underestimate of judged annoyance are applied to eight helicopter flyover noise signatures having various degrees of blade slap. A proposal for an impulsive noise correlation procedure based on a digital analysis of the flyover signal is investigated. When all data are combined, the proposal is little better than simply adding an arbitrary fixed adjustment of 3 decibels to EPNL.

  12. Numerical and experimental evidence of the inter-blade cavitation vortex development at deep part load operation of a Francis turbine

    Science.gov (United States)

    Yamamoto, K.; Müller, A.; Favrel, A.; Landry, C.; Avellan, F.

    2016-11-01

    Francis turbines are subject to various types of the cavitation flow depending on the operating conditions. In order to compensate for the stochastic nature of renewable energy sources, it is more and more required to extend the operating range of the generating units, from deep part load to full load conditions. In the deep part load condition, the formation of cavitation vortices in the turbine blade to blade channels called inter-blade cavitation vortex is often observed. The understanding of the dynamic characteristics of these inter-blade vortices and their formation mechanisms is of key importance in an effort of developing reliable flow simulation tools. This paper reports the numerical and experimental investigations carried out in order to establish the vortex characteristics, especially the inception and the development of the vortex structure. The unsteady RANS simulation for the multiphase flow is performed with the SST- SAS turbulence model by using the commercial flow solver ANSYS CFX. The simulation results in terms of the vortex structure and the cavitation volume are evaluated by comparing them to the flow visualizations of the blade channel acquired through a specially instrumented guide vane as well as from the downstream of the runner across the draft tube cone. The inter-blade cavitation vortex is successfully captured by the simulation and both numerical and experimental results evidence that the inter-blade vortices are attached to the runner hub.

  13. Pitched Blade Turbine Efficiency at Particle Suspension

    Directory of Open Access Journals (Sweden)

    D. Ceres

    2010-01-01

    Full Text Available Mixing suspensions is a very important hydraulic operation. The pitched six-blade turbine is a widely-used axial-flow impeller. This paper deals with effect relative impeller size and particle content on theefficiency of a pitched six-blade turbine at particle suspension. Two pitched six-blade turbines were used in model measurements of just suspension impeller speed. The ratios of the vessel to agitator diameter D/d were 3 and 4.5. The measurements were carried out in a dish-bottomed vessel 300 mm in diameter. The just suspension impeller speeds were measured using an electrochemical method, and were checked visually. A 2.5 % NaCl water solution was used as the liquid phase, and glass particles with four equivalent diameters between 0.18 and 0.89 mmand volumetric concentration from 2.5 % to 40% were usedasthesolid phase. The criterion values πs=Po√Fr'3(d/D7 were calculated from the particle suspension and power consumption measurements. The dependencies of πs on particle content cv show that larger agitators are more efficient for higher particle content.

  14. Noise aspects at aerodynamic blade optimisation projects

    Energy Technology Data Exchange (ETDEWEB)

    Schepers, J.G. [Netherlands Energy Research Foundation, Petten (Netherlands)

    1997-12-31

    This paper shows an example of an aerodynamic blade optimisation, using the program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. The aerodynamic optimised geometry from PVOPT is the `real` optimum (up to the latest decimal). The most important conclusion from this study is, that it is worthwhile to investigate the behaviour of the objective function (in the present case the energy yield) around the optimum: If the optimum is flat, there is a possibility to apply modifications to the optimum configuration with only a limited loss in energy yield. It is obvious that the modified configurations emits a different (and possibly lower) noise level. In the BLADOPT program (the successor of PVOPT) it will be possible to quantify the noise level and hence to assess the reduced noise emission more thoroughly. At present the most promising approaches for noise reduction are believed to be a reduction of the rotor speed (if at all possible), and a reduction of the tip angle by means of low lift profiles, or decreased twist at the outboard stations. These modifications were possible without a significant loss in energy yield. (LN)

  15. Development of the recovery technology for nickel superalloy blades of the aircraft engine by laser cladding

    Science.gov (United States)

    Bykovskiy, D. P.; Petrovskiy, V. N.; Polskiy, V. I.; Chirikov, S. N.; Dzhumaev, P. S.

    2016-09-01

    Development of cladding modes was performed with a superalloy nickel based powder on a flat substrate from material identical to compressor and turbine blades. Cross sections were made, and a visual inspection of the shape and the quality of the clad track as well as themetallographic analysis were performed. Microhardness of the deposition zone, chemical composition of the base, cladded metals, and the heat affected zone were determined.

  16. A parametric study of blade vortex interaction noise for two, three, and four-bladed model rotors at moderate tip speeds Theory and experiment

    Science.gov (United States)

    Leighton, K. P.; Harris, W. L.

    1984-01-01

    An investigation of blade slap due to blade vortex interaction (BVI) has been conducted. This investigation consisted of an examination of BVI blade slap for two, three, and four-bladed model rotors at tip Mach numbers ranging from 0.20 to 0.50. Blade slap contours have been obtained for each configuration tested. Differences in blade slap contours, peak sound pressure level, and directivity for each configuration tested are noted. Additional fundamental differences, such as multiple interaction BVI, are observed and occur for only specific rotor blade configurations. The effect of increasing the Mach number on the BVI blade slap for various rotor blade combinations has been quantified. A peak blade slap Mach number scaling law is proposed. Comparison of measured BVI blade slap with theory is made.

  17. Quantitative anatomy of grapevine (Vitis L. leaf blade

    Directory of Open Access Journals (Sweden)

    Valentine S. Codreanu

    2013-04-01

    Full Text Available Current investigations were conducted to clarify the features of grapevine which are adaptive to drought and can be used in selection and introduction of VitisL. There are determined biometric values of 21 morpho-anatomic characters of leaf blade for 10 species of grapevine, 10 cultivars of V. viniferaL. and 10 distant hybrids V. vinifera× Muscadinia rotundifoliaMichx. As a result of this study 6 leaf blade quantitative characters which determine relative grapevine drought resistance were described. The most drought resistant species, sorts and hybrids of grapevine are that which have: a greater average thickness of leaf blade; b smaller surface (average area of leaf blade; c less ratio between average area and average volume of dried leaf blade; d greater mass of dried leaf blade; e higher degrees of the leaf succulence and sclerophylly.

  18. Flow Characteristics Study of Wind Turbine Blade with Vortex Generators

    Directory of Open Access Journals (Sweden)

    Hao Hu

    2016-01-01

    Full Text Available The blade root flow control is of particular importance to the aerodynamic characteristic of large wind turbines. The paper studies the feasibility of improving blade pneumatic power by applying vortex generators (VGs to large variable propeller shaft horizontal axis wind turbines, with 2 MW variable propeller shaft horizontal axis wind turbine blades as research object. In the paper, three cases of VGs installation are designed; they are scattered in different chordwise position at the blade root, and then they are calculated, respectively, with CFD method. The results show that VGs installed in the separation line upstream, with the separation line of the blade root as a benchmark, show a better effect. Pneumatic power of blades increases by 0.6% by installing VGs. Although the effect on large wind turbines is not obvious, there is a space for optimization.

  19. Design modification in rotor blade of turbo molecular pump

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Munawar, E-mail: muniqbal@yahoo.com [Centre for High Energy Physics, University of the Punjab, Quaid-e-Azam, Campus, Lahore 54590 (Pakistan); Wasy, Abdul [Department of Mechanical Engineering, University of Engineering and Technology, Taxila 47050 (Pakistan); Batani, Dimitri [Centre Lasers Intenses et Applications, Universite Bordeaux 1, Liberation, 33405 Talence cedex (France); Rashid, Haris [Centre for High Energy Physics, University of the Punjab, Quaid-e-Azam, Campus, Lahore 54590 (Pakistan); Lodhi, M.A.K. [Department of Physics, Texas Tech University, Lubbock Texas, 79409 (United States)

    2012-06-21

    Performance of a Turbo Molecular Pump (TMP) is strongly related to the frequency of the rotor. As rpm increases deflection in the rotor blades starts to occur. Therefore, quality of material and blade design has been modified in order to obtain stable performance at higher speed. To reduce the deformation, stiffer material and change in blade design have been calculated. Significant improvement has been achieved in modeling the blade design using CATIA software. The analysis has been performed by ANSYS workbench. It is shown that the modification in the blade design of TMP rotor has reduced the structural deformation up to 66 percent of the deformation produced in the original blade design under the same conditions. Modified design achieved additional 23 percent rpm which increased TMP's efficiency.

  20. Design modification in rotor blade of turbo molecular pump

    Science.gov (United States)

    Iqbal, Munawar; Wasy, Abdul; Batani, Dimitri; Rashid, Haris; Lodhi, M. A. K.

    2012-06-01

    Performance of a Turbo Molecular Pump (TMP) is strongly related to the frequency of the rotor. As rpm increases deflection in the rotor blades starts to occur. Therefore, quality of material and blade design has been modified in order to obtain stable performance at higher speed. To reduce the deformation, stiffer material and change in blade design have been calculated. Significant improvement has been achieved in modeling the blade design using CATIA software. The analysis has been performed by ANSYS workbench. It is shown that the modification in the blade design of TMP rotor has reduced the structural deformation up to 66 percent of the deformation produced in the original blade design under the same conditions. Modified design achieved additional 23 percent rpm which increased TMP's efficiency.

  1. Sweep-twist adaptive rotor blade : final project report.

    Energy Technology Data Exchange (ETDEWEB)

    Ashwill, Thomas D.

    2010-02-01

    Knight & Carver was contracted by Sandia National Laboratories to develop a Sweep Twist Adaptive Rotor (STAR) blade that reduced operating loads, thereby allowing a larger, more productive rotor. The blade design used outer blade sweep to create twist coupling without angled fiber. Knight & Carver successfully designed, fabricated, tested and evaluated STAR prototype blades. Through laboratory and field tests, Knight & Carver showed the STAR blade met the engineering design criteria and economic goals for the program. A STAR prototype was successfully tested in Tehachapi during 2008 and a large data set was collected to support engineering and commercial development of the technology. This report documents the methodology used to develop the STAR blade design and reviews the approach used for laboratory and field testing. The effort demonstrated that STAR technology can provide significantly greater energy capture without higher operating loads on the turbine.

  2. Vibration-based SHM System: Application to Wind Turbine Blades

    DEFF Research Database (Denmark)

    Tcherniak, D.; Mølgaard, Lasse Lohilahti

    2015-01-01

    This study presents an vibration-based system designed for structural health monitoring of wind turbine blades. Mechanical energy is introduced by means of an electromechanical actuator mounted inside the blade. The actuator's plunger periodically hits the blade structure; the induced vibrations...... propagate along the blade and are measured by an array of accelerometers. Unsupervised learning is applied to the data: the vibration patterns corresponding to the undamaged blade are used to create a statistical model of the reference state. During the detection stage, the current vibration pattern...... is compared with the reference state, and the novelties can be associated with damage. The vibration pattern is described by the covariance matrix between the accelerometer signals. The mid-range frequencies are used: this range is above the frequencies excited by blade-wind interaction, thus ensuring a good...

  3. Digital Manufacture Techniques for Large Hydro Turbine's Blades

    Institute of Scientific and Technical Information of China (English)

    LAI Xide; ZHANG Qinghua; ZHOU Yunfei; YAN Sijie

    2006-01-01

    Blades are one of the vital components and most difficulty in manufacturing of large hydro turbines. In order to cost-effectively and productively manufacture these kinds of blades, a series of digital techniques in manufacturing have been developed, which includes digital design of hydro turbine blades based on manufacture' requirements, Computer-aided location and the machined error evaluation by using 3-dimensional digitized measuring, tool path generation strategy to meet requirements of enhancing machining efficiency and controlling deviation in NC machining, tool path generation and NC machining simulation by establishing a virtual NC machining environment for blades, and reasonable and feasible strategy and the systematic scheme for manufacturing of large blades by using 5-axis simultaneous CNC machining. The developed digital manufacture techniques have been successfully applied in manufacturing of both the large Kaplan and Francis hydraulic turbine blades; it shows that higher efficiency and the better surfaces finish accuracy can be achieved.

  4. Effect of Leading Edge Tubercles on Marine Tidal Turbine Blades

    Science.gov (United States)

    Murray, Mark; Gruber, Timothy; Fredriksson, David

    2010-11-01

    This project investigated the impact that the addition of leading edge protuberances (tubercles) have on the effectiveness of marine tidal turbine blades, especially at lower flow speeds. The addition of leading edge tubercles to lifting foils has been shown, in previous research, to delay the onset of stall without significant hydrodynamic costs. The experimental results obtained utilizing three different blade designs (baseline and two tubercle modified) are compared. All blades were designed in SolidWorks and manufactured utilizing rapid prototype techniques. All tests were conducted in the 120 ft tow tank at the U.S. Naval Academy using a specifically designed experimental apparatus. Results for power coefficients are presented for a range of tip speed ratios. Cut-in velocity is also compared between the blade designs. For all test criteria, the tubercle modified blades significantly outperformed the smooth leading edge baseline design blades.

  5. On the performance analysis of Savonius rotor with twisted blades

    Energy Technology Data Exchange (ETDEWEB)

    Saha, U.K.; Rajkumar, M. Jaya [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati-781 039 (India)

    2006-09-15

    The present investigation is aimed at exploring the feasibility of twisted bladed Savonius rotor for power generation. The twisted blade in a three-bladed rotor system has been tested in a low speed wind tunnel, and its performance has been compared with conventional semicircular blades (with twist angle of 0{sup o}). Performance analysis has been made on the basis of starting characteristics, static torque and rotational speed. Experimental evidence shows the potential of the twisted bladed rotor in terms of smooth running, higher efficiency and self-starting capability as compared to that of the conventional bladed rotor. Further experiments have been conducted in the same setup to optimize the twist angle. (author)

  6. A study on rotational augmentation using CFD analysis of flow in the inboard region of the MEXICO rotor blades

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Sørensen, Niels N.

    2015-01-01

    This work presents an analysis of data from existing as well as new full-rotor computational fluid dynamics computations on the MEXICO rotor, with focus on the flow around the inboard parts of the blades. The boundary layer separation characteristics on the airfoil sections in the inboard parts...

  7. Workplace availability, risk group and perceived barriers predictive of 2016-17 influenza vaccine uptake in the United States: A cross-sectional study.

    Science.gov (United States)

    Luz, Paula M; Johnson, Riley E; Brown, Heidi E

    2017-10-13

    Seasonal influenza, though mostly self-limited in the healthy adult, may lead to severe disease and/or complications in subpopulations. Annual influenza vaccination is available in many countries with coverage goals rarely being met. We conducted a cross-sectional study of influenza vaccine uptake and explored socio-demographic, economic, and psychological factors that explained vaccine uptake. The survey was administered via Amazon Mechanical Turk (MTurk) to United States residents in January 2017, using the Qualtrics platform. Using principal axis factor analysis, we reduced the 25 items theory-based psychological determinants into the primary constructs they measure if/when internal consistency was sufficient (Cronbach's alpha >0.60). Logistic regression models were used to quantify the association of socio-demographic, economic, and psychological factors with reported vaccine behavior in the 2016-17 flu season. 1007 participants completed the survey, sex distribution was even, 67% had 25-44years of age, and 61% annual household income of $30-99 thousand United States dollars. About 25% had the flu shot offered at their workplace and 20% reported belonging to a group for whom the flu shot is recommended. Vaccine uptake was 31.5%. Eight predictors remained in the final adjusted model (R(2)=0.489), having the vaccine offered at the workplace, belonging to a group for whom the vaccine is recommended, and higher perceived barriers were the strongest predictors of vaccine uptake, increasing (and decreasing in the case of barriers) the odds by >3-fold. Additionally, higher household income, higher perceived susceptibility and higher perceived benefits also independently predicted vaccine uptake. We found evidence that perceived barriers significantly impaired vaccine uptake to the same extent that having the vaccine offered at the workplace or belonging to a group for whom the vaccine is recommended facilitated uptake. Ideally, a better understanding of drivers of

  8. Reliability of wind turbine blades: An overview of materials testing

    DEFF Research Database (Denmark)

    Holmes, John W.; Sørensen, Bent F.; Brøndsted, Povl

    2007-01-01

    an understanding of how damage develops in composite structures, composite materials and adhesives. Designing reliable wind turbine blades also requires the further development of laboratory scale and full scale test methods to evaluate the structural response and durability of new materials under various loading...... and environmental conditions. This paper highlights recent advances in methods used to characterize adhesive joints in wind turbine blades and the manner in which laboratory data is used to predict the structural response of wind turbine blades....

  9. Wavelet Transformation for Damage Identication in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Skov, Jonas falk; Kirkegaard, Poul Henning

    2014-01-01

    The present paper documents a proposed modal and wavelet analysis-based structural health monitoring (SHM) method for damage identification in wind turbine blades. A finite element (FE) model of a full-scale wind turbine blade is developed and introduced to a transverse surface crack. Hereby, post...... of the first structural blade mode. However, due to the nature of the proposed method, it is also found that the accuracy of the damage assessment highly depends on the number of employed measurement points....

  10. Aerodynamic investigation of winglets on wind turbine blades using CFD

    OpenAIRE

    Johansen, Jeppe; Sørensen, Niels N.

    2006-01-01

    The present report describes the numerical investigation of the aerodynamics around a wind turbine blade with a winglet using Computational Fluid Dynamics, CFD. Five winglets were investigated with different twist distribution and camber. Four of themwere pointing towards the pressure side (upstream) and one was pointing towards the suction side (downstream). Additionally, a rectangular modification of the original blade tip was designed with the same planform area as the blades with winglets...

  11. Future Materials for Wind Turbine Blades - A Critical Review

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran

    2012-01-01

    Wind turbine industry is continuously evaluating material systems to replace the current thermoset composite technologies. Since turbine blades are the key component in the wind turbines and the size of the blade is increasing in today’s wind design, the material selection has become crucial...... higher performance under severe environmental conditions. The current article reviews various material alternatives and demonstrates the advantageous and disadvantageous for future wind turbine blade developments....

  12. A Critical Review of Future Materials for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran

    2014-01-01

    Wind turbine industry is continuously evaluating materials systems to replace the current thermoset composite technologies. Since turbine blades are the key component in the wind turbines and the size of the blade is increasing in todays wind design, the materials selection has become crucial...... higher performance under severe environmental conditions. The current article reviews various materials alternatives and demonstrates the advantages and disadvantages for future wind turbine blade developments....

  13. Measurement and Modelling of Multicopter UAS Rotor Blades in Hover

    Science.gov (United States)

    Nowicki, Nathalie

    2016-01-01

    deflection measurement of said blades and all theory is today based on the theory developed for full scale helicopters. This report thus intends to highlight the problems that come with blade deflection theory and measurements for multicopters. This thesis starts with the introduction and problem formulation where the grounds for what the report contains are laid out. Then a literature review of the research within the area follows where previous and current research and methods are presented. In the background information and theory relevant to the area are presented. After that the methods and set up of the different experimental and computer simulation approaches are depicted. In the results section the obtained results are presented and compared. Lastly there is a discussion where the results and methods are evaluated and analyzed, followed by the most important conclusions.

  14. Heat Transfer on a Film-Cooled Rotating Blade

    Science.gov (United States)

    Garg, Vijay K.

    1999-01-01

    A multi-block, three-dimensional Navier-Stokes code has been used to compute heat transfer coefficient on the blade, hub and shroud for a rotating high-pressure turbine blade with 172 film-cooling holes in eight rows. Film cooling effectiveness is also computed on the adiabatic blade. Wilcox's k-omega model is used for modeling the turbulence. Of the eight rows of holes, three are staggered on the shower-head with compound-angled holes. With so many holes on the blade it was somewhat of a challenge to get a good quality grid on and around the blade and in the tip clearance region. The final multi-block grid consists of 4784 elementary blocks which were merged into 276 super blocks. The viscous grid has over 2.2 million cells. Each hole exit, in its true oval shape, has 80 cells within it so that coolant velocity, temperature, k and omega distributions can be specified at these hole exits. It is found that for the given parameters, heat transfer coefficient on the cooled, isothermal blade is highest in the leading edge region and in the tip region. Also, the effectiveness over the cooled, adiabatic blade is the lowest in these regions. Results for an uncooled blade are also shown, providing a direct comparison with those for the cooled blade. Also, the heat transfer coefficient is much higher on the shroud as compared to that on the hub for both the cooled and the uncooled cases.

  15. INFLUENCE OF BLADES' STRESS STATE ON FRANCIS TURBINE RUNNER'S INVALIDATION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Numerical simulation on Francis turbine runner's welding temperature field and welding stress field is carried out on the base of solving the problem of welding heat source's movement along any spatial routes and the problem of heat elimination between the complicated blade and air. The evolvement law of welding stress and the distribution of the stress field after welding are obtained.The results indicate that the peak value of the welding residual stress appears on the outlet edge of blade near the contact area between blade and band or blade and crown. Associated with the distribution of the runner's working stress, the invalidation reason of the Francis turbine runner is explained.

  16. Unsteady aerodynamic interaction effects on turbomachinery blade life and performance

    Science.gov (United States)

    Adamczyk, John J.

    1992-01-01

    This paper is an attempt to address the impact of a class of unsteady flows on the life and performance of turbomachinery blading. These class of flows to be investigated are those whose characteristic frequency is an integral multiple of rotor shaft speed. Analysis of data recorded downstream of a compressor and turbine rotor will reveal that this class of flows can be highly three-dimensional and may lead to the generation of secondary flows within downstream blading. By explicitly accounting for these unsteady flows in the design of turbomachinery blading for multistage applications, it may be possible to bring about gains in performance and blade life.

  17. Defect distribution and reliability assessment of wind turbine blades

    DEFF Research Database (Denmark)

    Stensgaard Toft, Henrik; Branner, Kim; Berring, Peter

    2011-01-01

    In this paper, two stochastic models for the distribution of defects in wind turbine blades are proposed. The first model assumes that the individual defects are completely randomly distributed in the blade. The second model assumes that the defects occur in clusters of different size, based...... on the assumption that one error in the production process tends to trigger several defects. For both models, additional information, such as number, type, and size of the defects, is included as stochastic variables. In a numerical example, the reliability is estimated for a generic wind turbine blade model both...... the reliability for the wind turbine blade using Bayesian statistics....

  18. Modal characteristics and fatigue strength of compressor blades

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Kook [Doosan Heavy Industries and Construction, Changwon (Korea, Republic of); Lee, Young Shin [Chungnam National University, Daejeon (Korea, Republic of)

    2014-04-15

    High-cycle fatigue (HCF) has been identified as one of the primary causes of gas turbine engine failure. The modal characteristics and endurance strength of a 5 MW gas turbine engine blade developed by Doosan Heavy Industries and Construction Co., Ltd. in HCF fracture were verified through analysis and tests to determine the reliability of the compressor blade. A compressor blade design procedure that considers HCF life was performed in the following order: airfoil and blade profile design, modal analysis, stress distribution test, stress endurance limit test, and fatigue life verification. This study analyzed the Campbell diagram and estimated resonance risk on the basis of the natural frequency analysis and modal test of the compressor blade to guarantee safe and operational reliability. In addition, the maximum stress point of the compressor blade was determined through stress distribution analysis and test. The bonding point of the strain gage was determined by using fatigue test. Stress endurance limit test was performed based on the results of these tests. This research compared and verified the modal characteristics and endurance strengths of the compressor blades to prevent HCF fracture, which is among the major causes of gas turbine engine damage. A fatigue life design procedure of compressor blades was established. The 5 MW class gas turbine compressor blade is well designed in terms of resonance stability and fatigue endurance limit.

  19. Study of the helicopter blade running elevation measurement system

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Helicopter blade running elevation measurement is an important measure target in helicopter blade dynamic balance experimentation. The elevation influences the helicopter's security and other performance capabilities. In testing, however, it has been difficult to measure the elevation when the rotor reaches high speeds. To get a simple, fast and highly accurate measurement system, photo electricity technology was applied to measuring the blade running elevation. Discussed is the measurement principle of blade running elevation, the design of the measurement system and analysis of the measurement precision.

  20. Static Structural and Modal Analysis of Gas Turbine Blade

    Science.gov (United States)

    Ranjan Kumar, Ravi; Pandey, K. M., Prof.

    2017-08-01

    Gas turbine is one of the most versatile items of turbo machinery nowadays. It is used in different modes such as power generation, oil and gas, process plants, aviation, domestic and related small industries. This paper is based on the problems concerning blade profile selection, material selection and turbine rotor blade vibration that seriously impact the induced stress-deformation and structural functioning of developmental gas turbine engine. In this paper for generating specific power by rotating blade at specific RPM, blade profile and material has been decided by static structural analysis. Gas turbine rotating blade RPM is decided by Modal Analysis so that the natural frequency of blade should not match with the excitation frequency. For the above blade profile has been modeled in SOLIDWORKS and analysis has been done in ANSYS WORKBENCH 14. Existing NACA6409 profile has been selected as base model and then it is modified by bending it through 72.5° and 145°. Hence these three different blade profiles have been analyzed for three different materials viz. Super Alloy X, Nimonic 80A and Inconel 625 at three different speed viz. 20000, 40000 and 60000RPM. It is found that NACA6409 with 72.5° bent gives best result for all material at all speed. Among all the material Inconel 625 gives best result. Hence Blade of Inconel 625 having 72.5° bent profile is the best combination for all RPM.

  1. Modeling of uncertainties for wind turbine blade design

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Toft, Henrik Stensgaard

    2014-01-01

    Wind turbine blades are designed by a combination of tests and numerical calculations using finite element models of the blade. The blades are typically composite structures with laminates of glass-fiber and/or carbon-fibers glued together by a matrix material. This paper presents a framework...... basis in the JCSS framework for modelling material properties, Bayesian statistical methods allowing prior / expert knowledge to be accounted for and the Maximum Likelihood Method. The stochastic framework is illustrated using simulated tests which represent examples relevant for wind turbine blades....

  2. Wind Tunnel Test and Numerical Computation on Ice Accretion on Blade Airfoil for Straight-bladed VAWT

    Institute of Scientific and Technical Information of China (English)

    LI Shengmao; LI Yan; FENG Fang; WANG Lijun; CHI Yuan

    2010-01-01

    To invest the condition of ice accretion on the blade used for straight-bladed vertical axis wind turbine(SB-VAWT),wind tunnel tests were carded out on a blade with NACA0015 airfoil by using a small simple icing wind tunnel.Tests were carried out at some typical attack angles under different wind speeds and flow discharges of a water spray with wind.The icing shape and area on blade surface were recorded and measured.Then the numerical computation was carried out to calculate the lift and drag coefficients of the blade before and after ice accretion according to the experiment result,the effect of icing on the aerodynamic characteristics of blade were discussed.

  3. Toward an engineering model for the aerodynamic forces acting on wind turbine blades in quasisteady standstill and blade installation situations

    DEFF Research Database (Denmark)

    Gaunaa, Mac; Heinz, Joachim Christian; Skrzypinski, Witold Robert

    2016-01-01

    The crossflow principle is one of the key elements used in engineering models for prediction of the aerodynamic loads on wind turbine blades in standstill or blade installation situations, where the flow direction relative to the wind turbine blade has a component in the direction of the blade span...... direction. In the present work, the performance of the crossflow principle is assessed on the DTU 10MW reference blade using extensive 3D CFD calculations. Analysis of the computational results shows that there is only a relatively narrow region in which the crossflow principle describes the aerodynamic...... for the key aerodynamic loads in crossflow situations. The general validity of this model for other blade shapes should be investigated in subsequent works....

  4. Blade runner. Blade server and virtualization technology can help hospitals save money--but they are far from silver bullets.

    Science.gov (United States)

    Lawrence, Daphne

    2009-03-01

    Blade servers and virtualization can reduce infrastructure, maintenance, heating, electric, cooling and equipment costs. Blade server technology is evolving and some elements may become obsolete. There is very little interoperability between blades. Hospitals can virtualize 40 to 60 percent of their servers, and old servers can be reused for testing. Not all applications lend themselves to virtualization--especially those with high memory requirements. CIOs should engage their vendors in virtualization discussions.

  5. Experimental investigation of the influence of blade height and blade number on the performance of low head axial flow turbines

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Punit; Nestmann, Franz [Institute for Water and River Basin Management (IWG), University of Karlsruhe, Kaiser Str. 12, D 76128, Karlsruhe (Germany)

    2011-01-15

    Investigations regarding the influence of design parameters in low head axial flow turbines like blade profiles, blade height and blade number for micro-hydro application continue to be inadequate, even though there is a need and potential for the application of such turbines. This inadequacy provides a good ground to make a detailed experimental study to characterize these influences. The paper presents a holistic theoretical model that attempts to bring out a functionality of the internal performance parameters of the runner and attempts to establish a physical relationship between the two design parameters (blade height and blade number) and the performance parameters. The experimental results on 3 runners showed that with an increase in the number of blades, the efficiency of the runner dropped drastically due to the change in direction of the relative flow vector at the runner exit, which decreased the net rotational momentum and increased the axial flow velocity. The decrease of blade height on the other hand decreased the overall runner loss coefficient quite drastically but this could not result in major performance gains. The study concluded that the influence of blade number is more dominating compared to that of the blade height and that choice of blade number should be carefully made. On the hydraulic level, the study found interesting effects like the slip phenomenon and loss mechanisms within the runner. The paper also looks into the possible errors within the theoretical model developed and the extent of their influence on the conclusions. The paper suggests more experimental studies to separately study the effects of blade number and blade height. It further makes a strong case to initiate a computational work to validate all the experimental findings, fill the gaps in the theoretical model and use it as an optimization and standardization tool for axial flow turbines in the specialized application of micro-hydro. (author)

  6. Standard practice for examination of fiberglass reinforced plastic fan blades using acoustic emission

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice provides guidelines for acoustic emission (AE) examinations of fiberglass reinforced plastic (FRP) fan blades of the type used in industrial cooling towers and heat exchangers. 1.2 This practice uses simulated service loading to determine structural integrity. 1.3 This practice will detect sources of acoustic emission in areas of sensor coverage that are stressed during the course of the examination. 1.4 This practice applies to examinations of new and in-service fan blades. 1.5 This practice is limited to fan blades of FRP construction, with length (hub centerline to tip) of less than 3 m [10 ft], and with fiberglass content greater than 15 % by weight. 1.6 AE measurements are used to detect emission sources. Other nondestructive examination (NDE) methods may be used to evaluate the significance of AE sources. Procedures for other NDE methods are beyond the scope of this practice. 1.7 Units—The values stated in either SI units or inch-pound units are to be regarded separately as sta...

  7. Staff working in hospital units with greater social capital experience less work-home conflict: Secondary analysis of a cross-sectional study.

    Science.gov (United States)

    Nitzsche, Anika; Kuntz, Ludwig; Miedaner, Felix

    2017-07-31

    When the interplay between work and private life does not function correctly (work-home conflict), this constitutes a well-known risk factor for poorer health, increased absenteeism and lower work performance. Information about influencing factors of work-home conflict is therefore indispensable in order to avoid it. In this study, we analyse whether a good working atmosphere that fosters mutual trust, support and a 'sense of unity' (organizational social capital) can reduce an employee's conflict between work and private life. This study investigates the link between organizational social capital and work-home conflict in health professionals. This issue was investigated using a cross-sectional study conducted in 2013. Data from questionnaires completed by physicians and nurses (n=1733) were linked with structural data from 66 neonatal intensive care units in Germany. Using multi-level analyses, we investigated associations between organizational social capital at the ward level and work-home conflict at the level of individual employees, taking into account additional structural and individual characteristics. Employees on wards with greater social capital reported significantly less work-home conflict. Our results support the hypothesis that organizational social capital is an important collective resource. As such, more attention should be given to establishing a good working atmosphere that fosters mutual trust, support and a 'sense of unity', and this should be encouraged in a targeted fashion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. A new blade element method for calculating the performance of high and intermediate solidity axial flow fans

    Science.gov (United States)

    Borst, H. V.

    1978-01-01

    A method is presented to design and predict the performance of axial flow rotors operating in a duct. The same method is suitable for the design of ducted fans and open propellers. The unified method is based on the blade element approach and the vortex theory for determining the three dimensional effects, so that two dimensional airfoil data can be used for determining the resultant force on each blade element. Resolution of this force in the thrust and torque planes and integration allows the total performance of the rotor, fan or propeller to be predicted. Three different methods of analysis, one based on a momentum flow theory; another on the vortex theory of propellers; and a third based on the theory of ducted fans, agree and reduce cascade airfoil data to single line as a function of the loading and induced angle of attack at values of constant inflow angle. The theory applies for any solidity from .01 to over 1 and any blade section camber. The effects of the duct and blade number can be determined so that the procedure applies over the entire range from two blade open propellers, to ducted helicopter tail rotors, to axial flow compressors with or without guide vanes, and to wind tunnel drive fans.

  9. Aerodynamic optimization of wind turbine rotors using a blade element momentum method with corrections for wake rotation and expansion

    DEFF Research Database (Denmark)

    Døssing, Mads; Aagaard Madsen, Helge; Bak, Christian

    2012-01-01

    by the positive effect of wake rotation, which locally causes the efficiency to exceed the Betz limit. Wake expansion has a negative effect, which is most important at high tip speed ratios. It was further found that by using , it is possible to obtain a 5% reduction in flap bending moment when compared with BEM......The blade element momentum (BEM) method is widely used for calculating the quasi-steady aerodynamics of horizontal axis wind turbines. Recently, the BEM method has been expanded to include corrections for wake expansion and the pressure due to wake rotation (), and more accurate solutions can now...... be obtained in the blade root and tip sections. It is expected that this will lead to small changes in optimum blade designs. In this work, has been implemented, and the spanwise load distribution has been optimized to find the highest possible power production. For comparison, optimizations have been carried...

  10. Application of transition modelling in CFD for use with turbine blades

    CSIR Research Space (South Africa)

    Dunn, Dwain I

    2011-09-01

    Full Text Available The design of internally-cooled gas turbine blades requires accurate predictions of distributions of blade temperature values and temperature gradients. This requires accurate predictions of heat transfer distributions from the hot gas (on the blade...

  11. Blade Vibration Measurement System for Characterization of Closely Spaced Modes and Mistuning Project

    Data.gov (United States)

    National Aeronautics and Space Administration — There are several ongoing challenges in non-contacting blade vibration and stress measurement systems that can address closely spaced modes and blade-to-blade...

  12. The SNL100-03 Blade: Design Studies with Flatback Airfoils for the Sandia 100-meter Blade.

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, Daniel; Richards, Phillip William

    2014-09-01

    A series of design studies were performed to inv estigate the effects of flatback airfoils on blade performance and weight for large blades using the Sandi a 100-meter blade designs as a starting point. As part of the study, the effects of varying the blade slenderness on blade structural performance was investigated. The advantages and disadvantages of blad e slenderness with respect to tip deflection, flap- wise & edge-wise fatigue resistance, panel buckling capacity, flutter speed, manufacturing labor content, blade total weight, and aerodynamic design load magn itude are quantified. Following these design studies, a final blade design (SNL100-03) was prod uced, which was based on a highly slender design using flatback airfoils. The SNL100-03 design with flatback airfoils has weight of 49 tons, which is about 16% decrease from its SNL100-02 predecessor that used conventional sharp trailing edge airfoils. Although not systematically optimized, the SNL100 -03 design study provides an assessment of and insight into the benefits of flatback airfoils for la rge blades as well as insights into the limits or negative consequences of high blade slenderness resulting from a highly slender SNL100-03 planform as was chosen in the final design definition. This docum ent also provides a description of the final SNL100-03 design definition and is intended to be a companion document to the distribution of the NuMAD blade model files for SNL100-03, which are made publicly available. A summary of the major findings of the Sandia 100-meter blade development program, from the initial SNL100-00 baseline blade through the fourth SNL100-03 blade study, is provided. This summary includes the major findings and outcomes of blade d esign studies, pathways to mitigate the identified large blade design drivers, and tool development that were produced over the course of this five-year research program. A summary of large blade tec hnology needs and research opportunities is also presented.

  13. Toward an Engineering Model for the Aerodynamic Forces Acting on Wind Turbine Blades in Quasisteady Standstill and Blade Installation Situations

    Science.gov (United States)

    Gaunaa, Mac; Heinz, Joachim; Skrzypiński, Witold

    2016-09-01

    The crossflow principle is one of the key elements used in engineering models for prediction of the aerodynamic loads on wind turbine blades in standstill or blade installation situations, where the flow direction relative to the wind turbine blade has a component in the direction of the blade span direction. In the present work, the performance of the crossflow principle is assessed on the DTU 10MW reference blade using extensive 3D CFD calculations. Analysis of the computational results shows that there is only a relatively narrow region in which the crossflow principle describes the aerodynamic loading well. In some conditions the deviation of the predicted loadings can be quite significant, having a large influence on for instance the integral aerodynamic moments around the blade centre of mass; which is very important for single blade installation applications. The main features of these deviations, however, have a systematic behaviour on all force components, which in this paper is employed to formulate the first version of an engineering correction method to the crossflow principle applicable for wind turbine blades. The new correction model improves the agreement with CFD results for the key aerodynamic loads in crossflow situations. The general validity of this model for other blade shapes should be investigated in subsequent works.

  14. Smart actuation mechanisms for helicopter blades: design case for a mach-scaled model blade

    NARCIS (Netherlands)

    Paternoster, Alexandre

    2013-01-01

    This work is part of the European project “Clean Sky”, which aims at improving the efficiency and the global transport quality of aircraft. The research, in this project, is currently focussing on active flap systems for helicopters to adapt the blade aerodynamic properties to local aerodynamic

  15. Simulation of Flexible Mechanisms in a Rotating Blade for Smart-Blade Applications

    NARCIS (Netherlands)

    Paternoster, A.R.A.; Loendersloot, R.; Boer, de A.; Akkerman, R.

    2012-01-01

    The active Gurney flap technology is investigated to improve the performance of rotorblades by allowing helicopter blades to further control the lift unbalance that rises at high speed and by damping vibration loads on the rotor hub. This technology needs validation by wind tunnel testing of a scale

  16. Smart actuation mechanisms for helicopter blades: design case for a mach-scaled model blade

    NARCIS (Netherlands)

    Paternoster, A.R.A.

    2013-01-01

    This work is part of the European project “Clean Sky”, which aims at improving the efficiency and the global transport quality of aircraft. The research, in this project, is currently focussing on active flap systems for helicopters to adapt the blade aerodynamic properties to local aerodynamic cond

  17. Numerical simulation on a straight-bladed vertical axis wind turbine with auxiliary blade

    Science.gov (United States)

    Li, Y.; Zheng, Y. F.; Feng, F.; He, Q. B.; Wang, N. X.

    2016-08-01

    To improve the starting performance of the straight-bladed vertical axis wind turbine (SB-VAWT) at low wind speed, and the output characteristics at high wind speed, a flexible, scalable auxiliary vane mechanism was designed and installed into the rotor of SB-VAWT in this study. This new vertical axis wind turbine is a kind of lift-to-drag combination wind turbine. The flexible blade expanded, and the driving force of the wind turbines comes mainly from drag at low rotational speed. On the other hand, the flexible blade is retracted at higher speed, and the driving force is primarily from a lift. To research the effects of the flexible, scalable auxiliary module on the performance of SB-VAWT and to find its best parameters, the computational fluid dynamics (CFD) numerical calculation was carried out. The calculation result shows that the flexible, scalable blades can automatic expand and retract with the rotational speed. The moment coefficient at low tip speed ratio increased substantially. Meanwhile, the moment coefficient has also been improved at high tip speed ratios in certain ranges.

  18. Simulation of Flexible Mechanisms in a Rotating Blade for Smart-Blade Applications

    NARCIS (Netherlands)

    Paternoster, Alexandre; Loendersloot, Richard; de Boer, Andries; Akkerman, Remko

    2012-01-01

    The active Gurney flap technology is investigated to improve the performance of rotorblades by allowing helicopter blades to further control the lift unbalance that rises at high speed and by damping vibration loads on the rotor hub. This technology needs validation by wind tunnel testing of a

  19. Proximal Blade Twist Feedback Control for Heliogyro Solar Sails

    Science.gov (United States)

    Smith, Sarah Mitchell

    A heliogyro spacecraft is a specific type of solar sail that generates thrust from the reflection of solar photons. It consists of multiple long (200 to 600 meters), thin blades, similar to a helicopter. The heliogyro's blades remain in tension by spinning around the central hub of the spacecraft. The individual blades are pitched collectively or cyclically to produce the desired maneuver profile. The propellant-free heliogyro is a long-duration sustainable spacecraft whose maneuverability allows it to attain previously inaccessible orbits for traditional spacecraft. The blades are constructed from thin Mylar sheets, approximately 2.5 ?m thick, which have very little inherent damping making it necessary to include some other way of attenuating blade vibration caused by maneuvering. The most common approach is to incorporate damping through the root pitch actuator. However, due to the small root pitch control torques required, on the order of 2 ?Nm, compared to the large friction torques associated with a root pitch actuator, it is challenging to design a root control system that takes friction into account and can still add damping to the blade. The purpose of this research is to address the limitations of current control designs for a heliogyro spacecraft and to develop a physically realizable root pitch controller that effectively damps the torsional structural modes of a single heliogyro blade. Classical control theory in conjunction with impedance control techniques are used to design a position-source root pitch controller to dominate friction with high gains, wrapped with an outer loop that adds damping to the blade by sensing differential twist outboard of the blade root. First, modal parameter characterization experiments were performed on a small-scale heliogyro blade in a high vacuum chamber to determine a damping constant to be used in the membrane ladder finite element model of the blade. The experimental damping ratio of the lowest frequency torsional

  20. Striation patterns in serrated blade stabs to cartilage.

    Science.gov (United States)

    Pounder, Derrick J; Reeder, Francesca D

    2011-05-20

    Stab wounds were made in porcine cartilage with 13 serrated knives, amongst which 4 were drop-point and 9 straight-spine; 9 coarsely serrated, 3 finely serrated and 1 with mixed pattern serrations. The walls of the stab tracks were cast with dental impression material, and the casts photographed together with the knife blades for comparison. All 13 serrated blades produced an "irregularly regular" pattern of striations on cartilage in all stabbings. Unusual and distinctive blade serration patterns produced equally distinctive wound striation patterns. A reference collection of striation patterns and corresponding blades might prove useful for striation pattern analysis. Drop-point blades produced similar striations to straight-spine blades except that the striations were not parallel but rather fan-shaped, converging towards the wound exit. The fan-shaped striation pattern characteristic of drop-point blades is explained by the initial lateral movement of the blade through the cartilage imposed by the presence of the drop point shape. It appears that the greater the overall angle of the drop point, the shorter the blade length over which the drop point occurs, and the closer the first serration is to the knife tip, the more obvious is the fan-shaped pattern. We anticipate that micro-irregularities producing individualising characteristics in non-serrated drop point blades, provided they were located at the tip opposite the drop point, should also show a fan-shaped pattern indicative of a drop point blade. The examination of the walls of stab wounds to cartilage represents an under-utilised source of forensic information to assist in knife identification.

  1. Active Blade Vibration Control Being Developed and Tested

    Science.gov (United States)

    Johnson, Dexter

    2003-01-01

    Gas turbine engines are currently being designed to have increased performance, lower weight and manufacturing costs, and higher reliability. Consequently, turbomachinery components, such as turbine and compressor blades, have designs that are susceptible to new vibration problems and eventual in-service failure due to high-cycle fatigue. To address this problem, researchers at the NASA Glenn Research Center are developing and testing innovative active blade vibration control concepts. Preliminary results of using an active blade vibration control system, involving a rotor supported by an active magnetic bearing in Glenn's Dynamic Spin Rig, indicate promising results (see the photograph). Active blade vibration control was achieved using feedback of blade strain gauge signals within the magnetic bearing control loop. The vibration amplitude was reduced substantially (see the graphs). Also, vibration amplitude amplification was demonstrated; this could be used to enhance structural mode identification, if desired. These results were for a nonrotating two-bladed disk. Tests for rotating blades are planned. Current and future active blade vibration control research is planned to use a fully magnetically suspended rotor and smart materials. For the fully magnetically suspended rotor work, three magnetic bearings (two radial and one axial) will be used as actuators instead of one magnetic bearing. This will allow additional degrees of freedom to be used for control. For the smart materials work, control effectors located on and off the blade will be considered. Piezoelectric materials will be considered for on-the-blade actuation, and actuator placement on a stator vane, or other nearby structure, will be investigated for off-the-blade actuation. Initial work will focus on determining the feasibility of these methods by performing basic analysis and simple experiments involving feedback control.

  2. Blade Profile Optimization of Kaplan Turbine Using CFD Analysis

    Directory of Open Access Journals (Sweden)

    Aijaz Bashir Janjua

    2013-10-01

    Full Text Available Utilization of hydro-power as renewable energy source is of prime importance in the world now. Hydropower energy is available in abundant in form of falls, canals rivers, dams etc. It means, there are various types of sites with different parameters like flow rate, heads, etc. Depending upon the sites, water turbines are designed and manufactured to avail hydro-power energy. Low head turbines on runof-river are widely used for the purpose. Low head turbines are classified as reaction turbines. For runof river, depending upon the variety of site data, low head Kaplan turbines are selected, designed and manufactured. For any given site requirement, it becomes very essential to design the turbine runner blades through optimization of the CAD model of blades profile. This paper presents the optimization technique carried out on a complex geometry of blade profile through static and dynamic computational analysis. It is used through change of the blade profile geometry at five different angles in the 3D (Three Dimensional CAD model. Blade complex geometry and design have been developed by using the coordinates point system on the blade in PRO-E /CREO software. Five different blade models are developed for analysis purpose. Based on the flow rate and heads, blade profiles are analyzed using ANSYS software to check and compare the output results for optimization of the blades for improved results which show that by changing blade profile angle and its geometry, different blade sizes and geometry can be optimized using the computational techniques with changes in CAD models.

  3. Analysis of turbomachine viscous losses affected by changes in blade geometry

    Science.gov (United States)

    Miser, James W; Stewart, Warner L; Whitney, Warren J

    1956-01-01

    The effect of changes in blade geometry on the viscous losses in turbomachines is analyzed. The viscous losses can be expressed as a function of three variables: the blade height-to spacing ratio, the solidity, and a blade-height Reynolds number. A method of optimizing the number of blades and the solidity is given. The effect of trailing-edge blockage on blade loss and its effect on the choice of blade number for a particular design are also discussed.

  4. Quality of drug prescribing in elderly people in nursing homes and special care units for dementia: a cross-sectional computerized pharmacy register analysis.

    Science.gov (United States)

    Olsson, Jonny; Bergman, Asa; Carlsten, Anders; Oké, Thimothy; Bernsten, Cecilia; Schmidt, Ingrid K; Fastbom, Johan

    2010-01-01

    Drug prescribing to the elderly is extensive and often inappropriate. Furthermore, the number of drugs used is the most important risk factor for adverse drug reactions. Despite this, drug prescribing in the elderly in Sweden is high and increasing. In 2003 the Swedish National Board of Health and Welfare launched a set of indicators to evaluate the quality of drug therapy in the elderly. Use of this tool in combination with the Swedish computerized national register covering all persons receiving multi-dose drug dispensing (drugs dispensed in one dose unit bag for each dose occasion) would enable detection of inappropriate drug prescribing and could help reduce the risk of drug-related problems among the elderly. To assess the extent and quality of drug prescribing in younger and older elderly residents receiving multi-dose drug dispensing in ordinary nursing homes (NHs) and special care units for dementia (NHDs), and to evaluate the relationship between the quality of prescribing and the number of prescribers per resident, in a Swedish county. The computerized national pharmacy drug register provided the database and a cross-sectional design was used. Selected drug-specific quality indicators proposed by the Swedish National Board of Health and Welfare in 2003 were used to assess the quality of drug prescribing. This study included 3705 residents. Their mean age was 85 years and 72% were women. The mean number of prescribed drugs was 10.3 per resident. The proportion of residents with prescriptions for psychotropic drugs was 80% in NHs and 85% in NHDs. The prevalence of each drug-specific quality indicator was as follows: long-acting benzodiazepines 16.4% (NHs) versus 11.7% (NHDs), anticholinergic drugs 20.7% versus 18.5%, drug duplication 14.6% versus 13.6%, three or more psychotropic drugs 25.6% versus 35.3%, class C interactions (drug combinations that may require dose adjustment) 41.9% versus 38.7% and class D interactions (drug combinations that should be

  5. Bed Utilisation in an Irish Regional Paediatric Unit – A Cross-Sectional Study Using the Paediatric Appropriateness Evaluation Protocol (PAEP

    Directory of Open Access Journals (Sweden)

    Coilín ÓhAiseadha

    2016-11-01

    Full Text Available Background Increasing demand for limited healthcare resources raises questions about appropriate use of inpatient beds. In the first paediatric bed utilisation study at a regional university centre in Ireland, we conducted a cross-sectional study to audit the utilisation of inpatient beds at the Regional Paediatric Unit (RPU in University Hospital Limerick (UHL, Limerick, Ireland and also examined hospital activity data, to make recommendations for optimal use of inpatient resources. Methods We used a questionnaire based on the paediatric appropriateness evaluation protocol (PAEP, modified and validated for use in the United Kingdom, to prospectively gather data regarding reasons for admission and for ongoing care after 2 days, from case records for all inpatients during 11 days in February (winter and 7 days in May–June (summer. We conducted bivariate and multivariate analysis to explore associations between failure to meet PAEP criteria and patient attributes including age, gender, admission outside of office hours, arrival by ambulance, and private health insurance. Inpatient bed occupancy and day ward activity were also scrutinised. Results Mean bed occupancy was 84.1%. In all, 12/355 (3.4%, 95% CI: 1.5%–5.3% of children failed to meet PAEP admission criteria, and 27/189 (14.3%, 95% CI: 9.3%–19.3% who were still inpatients after 2 days failed to meet criteria for ongoing care. 35/355 (9.9%, 95% CI: 6.8%–13.0% of admissions fulfilled only the PAEP criterion for intravenous medications or fluid replacement. A logistic regression model constructed by forward selection identified a significant association between failure to meet PAEP criteria for ongoing care 2 days after admission and admission during office hours (08.00–17.59 (P = .020, and a marginally significant association between this outcome and arrival by ambulance (P = .054. Conclusion At a mean bed occupancy of 84.1%, an Irish RPU can achieve 96.6% appropriate admissions

  6. A cross-sectional analysis of patterns of obesity in a cohort of working nurses and midwives in Australia, New Zealand, and the United Kingdom.

    Science.gov (United States)

    Bogossian, Fiona E; Hepworth, Julie; Leong, Gary M; Flaws, Dylan F; Gibbons, Kristen S; Benefer, Christine A; Turner, Catherine T

    2012-06-01

    The aim of this study was to examine the prevalence of overweight and obesity and the association with demographic, reproductive work variables in a representative cohort of working nurses and midwives. A cross sectional study of self reported survey data. Australia, New Zealand and the United Kingdom. Measurement outcomes included BMI categories, demographic (age, gender, marital status, ethnicity), reproductive (parity, number of births, mother's age at first birth, birth type and menopausal status) and workforce (registration council, employment type and principal specialty) variables. 4996 respondents to the Nurses and Midwives e-Cohort study who were currently registered and working in nursing or midwifery in Australia (n=3144), New Zealand (n=778) or the United Kingdom (n=1074). Amongst the sample 61.87% were outside the healthy weight range and across all three jurisdictions the prevalence of obesity in nurses and midwives exceeded rates in the source populations by 1.73% up to 3.74%. Being overweight or obese was significantly associated with increasing age (35-44 yrs aOR 1.71, 95% CI 1.41-2.08; 45-55 yrs aOR 1.90, 95%CI 1.56-2.31; 55-64 aOR 2.22, 95% CI 1.71-2.88), and male gender (aOR 1.46, 95% CI 1.15-1.87). Primiparous nurses and midwives were more likely to be overweight or obese (aOR 1.37, 95% CI 1.06-1.76) as were those who had reached menopause (aOR 1.37, 95% CI 1.11-1.69). Nurses and midwives in part-time or casual employment had significantly reduced risk of being overweight or obese, (aOR 0.81, 95% CI 0.70-0.94 and aOR 0.75, 95% CI 0.59-0.96 respectively), whilst working in aged carried increased risk (aOR 1.37, 95% CI 1.04-1.80). Nurses and midwives in this study have higher prevalence of obesity and overweight than the general population and those who are older, male, or female primiparous and menopausal have significantly higher risk of overweight or obesity as do those working fulltime, or in aged care. The consequences of overweight and

  7. Bed Utilisation in an Irish Regional Paediatric Unit – A Cross-Sectional Study Using the Paediatric Appropriateness Evaluation Protocol (PAEP)

    Science.gov (United States)

    ÓhAiseadha, Coilín; Mannix, Mai; Saunders, Jean; Philip, Roy K.

    2016-01-01

    Background: Increasing demand for limited healthcare resources raises questions about appropriate use of inpatient beds. In the first paediatric bed utilisation study at a regional university centre in Ireland, we conducted a cross-sectional study to audit the utilisation of inpatient beds at the Regional Paediatric Unit (RPU) in University Hospital Limerick (UHL), Limerick, Ireland and also examined hospital activity data, to make recommendations for optimal use of inpatient resources. Methods: We used a questionnaire based on the paediatric appropriateness evaluation protocol (PAEP), modified and validated for use in the United Kingdom, to prospectively gather data regarding reasons for admission and for ongoing care after 2 days, from case records for all inpatients during 11 days in February (winter) and 7 days in May–June (summer). We conducted bivariate and multivariate analysis to explore associations between failure to meet PAEP criteria and patient attributes including age, gender, admission outside of office hours, arrival by ambulance, and private health insurance. Inpatient bed occupancy and day ward activity were also scrutinised. Results: Mean bed occupancy was 84.1%. In all, 12/355 (3.4%, 95% CI: 1.5%–5.3%) of children failed to meet PAEP admission criteria, and 27/189 (14.3%, 95% CI: 9.3%–19.3%) who were still inpatients after 2 days failed to meet criteria for ongoing care. 35/355 (9.9%, 95% CI: 6.8%–13.0%) of admissions fulfilled only the PAEP criterion for intravenous medications or fluid replacement. A logistic regression model constructed by forward selection identified a significant association between failure to meet PAEP criteria for ongoing care 2 days after admission and admission during office hours (08.00–17.59) (P = .020), and a marginally significant association between this outcome and arrival by ambulance (P = .054). Conclusion: At a mean bed occupancy of 84.1%, an Irish RPU can achieve 96.6% appropriate admissions

  8. Loads and Performance Data from a Wind-Tunnel Test of Generic Model Helicopter Rotor Blades

    Science.gov (United States)

    Yeager, William T., Jr.; Wilbur, Matthew L.

    2005-01-01

    An investigation was conducted in the NASA Langley Transonic Dynamics Tunnel to acquire data for use in assessing the ability of current and future comprehensive analyses to predict helicopter rotating-system and fixed-system vibratory loads. The investigation was conducted with a generic model helicopter rotor system using blades with rectangular planform, no built-in twist, uniform radial distribution of mass and stiffnesses, and a NACA 0012 airfoil section. Rotor performance data, as well as mean and vibratory components of blade bending and torsion moments, fixed-system forces and moments, and pitch link loads were obtained at advance ratios up to 0.35 for various combinations of rotor shaft angle-of-attack and collective pitch. The data are presented without analysis.

  9. A stochastic model for the simulation of wind turbine blades in static stall

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Rasmussen, Flemming; Sørensen, Niels N.;

    2010-01-01

    The aim of this work is to improve aeroelastic simulation codes by accounting for the unsteady aerodynamic forces that a blade experiences in static stall. A model based on a spectral representation of the aerodynamic lift force is defined. The drag and pitching moment are derived using a conditi......The aim of this work is to improve aeroelastic simulation codes by accounting for the unsteady aerodynamic forces that a blade experiences in static stall. A model based on a spectral representation of the aerodynamic lift force is defined. The drag and pitching moment are derived using...... a conditional simulation technique for stochastic processes. The input data for the model can be collected either from measurements or from numerical results from a Computational Fluid Dynamics code for airfoil sections at constant angles of attack. An analysis of such data is provided, which helps to determine...

  10. Design of turbomachinery blading in three-dimensional flow by the circulation method

    Science.gov (United States)

    Hawthorne, W. R.; Tan, C. S.

    1987-01-01

    In this paper, we report on the progress of the further development and application of an analytical theory for the design of turbomachinery blading in three-dimensional flow. After a section describing the recent development of the theory, we discuss the various applications including the investigations of the design of radial inflow turbines. Numerical examples are also presented to illustrate the application of the theory to the design of a free vortex fan, an axial turbine rotor, a free vortex compressor stage for low and high Mach numbers, a non-free vortex fan with trailing vortex sheets, and a counter-rotating propeller in the limit of a large number of blades. Further possible applications of the theory to the design of other aero- and hydrodynamic devices are discussed.

  11. Muscle Torque Relative to Cross-Sectional Area and the Functional Muscle-Bone Unit in Children and Adolescents with Chronic Disease

    Science.gov (United States)

    Lee, Dale Y.; Wetzsteon, Rachel J.; Zemel, Babette S.; Shults, Justine; Organ, Jason M.; Foster, Bethany J.; Herskovitz, Rita M.; Foerster, Debbie L.; Leonard, Mary B.

    2015-01-01

    Measures of muscle mass or size are often used as surrogates of forces acting on bone. However, chronic diseases may be associated with abnormal muscle force relative to muscle size. The muscle-bone unit was examined in 64 children and adolescents with new-onset Crohn’s disease (CD), 54 with chronic kidney disease (CKD), 51 treated with glucocorticoids for nephrotic syndrome (NS), and 264 healthy controls. Muscle torque was assessed by isometric ankle dynamometry. Calf muscle cross-sectional area (CSA) and tibia cortical section modulus (Zp) were assessed by quantitative CT. Log-linear regression was used to determine the relations among muscle CSA, muscle torque, and Zp, adjusted for tibia length, age, Tanner stage, sex, and race. Muscle CSA and muscle torque-relative-to-muscle CSA were significantly lower than controls in advanced CKD (CSA −8.7%, p = 0.01; torque −22.9%, p < 0.001) and moderate-to-severe CD (CSA −14.1%, p < 0.001; torque −7.6%, p = 0.05), but not in NS. Zp was 11.5% lower in advanced CKD (p = 0.005) compared to controls, and this deficit was attenuated to 6.7% (p = 0.05) with adjustment for muscle CSA. With additional adjustment for muscle torque and body weight, Zp was 5.9% lower and the difference with controls was no longer significant (p = 0.09). In participants with moderate-to-severe CD, Zp was 6.8% greater than predicted (p = 0.01) given muscle CSA and torque deficits (R2=0.92), likely due to acute muscle loss in newly diagnosed patients. Zp did not differ in NS, compared with controls. In conclusion, muscle torque relative to muscle CSA was significantly lower in CKD and CD, compared with controls, and was independently associated with Zp. Future studies are needed to determine if abnormal muscle strength contributes to progressive bone deficits in chronic disease, independent of muscle area. PMID:25264231

  12. Through flow analysis within axial flow turbomachinery blade rows

    Science.gov (United States)

    Girigoswami, H.

    1986-09-01

    Using Katsanis' Through Flow Code, inviscid flow through an axial flow compressor rotor blade as well as flow through inlet guide vanes are analyzed and the computed parameters such as meridional velocity distribution, axial velocity distribution along radial lines, and velocity distribution over blade surfaces are presented.

  13. Crack Diagnosis of Wind Turbine Blades Based on EMD Method

    Science.gov (United States)

    Hong-yu, CUI; Ning, DING; Ming, HONG

    2016-11-01

    Wind turbine blades are both the source of power and the core technology of wind generators. After long periods of time or in some extreme conditions, cracks or damage can occur on the surface of the blades. If the wind generators continue to work at this time, the crack will expand until the blade breaks, which can lead to incalculable losses. Therefore, a crack diagnosis method based on EMD for wind turbine blades is proposed in this paper. Based on aerodynamics and fluid-structure coupling theory, an aero-elastic analysis on wind turbine blades model is first made in ANSYS Workbench. Second, based on the aero-elastic analysis and EMD method, the blade cracks are diagnosed and identified in the time and frequency domains, respectively. Finally, the blade model, strain gauge, dynamic signal acquisition and other equipment are used in an experimental study of the aero-elastic analysis and crack damage diagnosis of wind turbine blades to verify the crack diagnosis method proposed in this paper.

  14. Are inclined screw blades for vertical grain augers advantageous?

    NARCIS (Netherlands)

    Rademacher, F.J.C.

    1978-01-01

    Due to modern technology, screw blades are often manufactured by rolling them out of one single strip of steel. When simultaneously some blade inclination is applied, less residual stresses and/or larger possible ratios between outer and shaft diameter are claimed by some manufacturers, which seems

  15. Vibration-based SHM System: Application to Wind Turbine Blades

    Science.gov (United States)

    Tcherniak, D.; Mølgaard, L. L.

    2015-07-01

    This study presents an vibration-based system designed for structural health monitoring of wind turbine blades. Mechanical energy is introduced by means of an electromechanical actuator mounted inside the blade. The actuator's plunger periodically hits the blade structure; the induced vibrations propagate along the blade and are measured by an array of accelerometers. Unsupervised learning is applied to the data: the vibration patterns corresponding to the undamaged blade are used to create a statistical model of the reference state. During the detection stage, the current vibration pattern is compared with the reference state, and the novelties can be associated with damage. The vibration pattern is described by the covariance matrix between the accelerometer signals. The mid-range frequencies are used: this range is above the frequencies excited by blade-wind interaction, thus ensuring a good signal-to-noise ratio. Simultaneously, the frequencies are low enough to be able to propagate the entire blade length, so good results can be obtained even using only one actuator. The system is demonstrated on a real 34m blade mounted on a test rig. Using the suggested approach, the system enables detection of, e.g., a 20cm long trailing edge opening under realistic noise conditions. It is also demonstrated that the system provides rough information about damage location. Progression of damage, if any, can also be detected.

  16. Accelerated rain erosion of wind turbine blade coatings

    DEFF Research Database (Denmark)

    Zhang, Shizhong

    During operation, the fast-moving blades of wind turbines are exposed to continuous impacts with rain droplets, hail, insects, or solid particles. This can lead to erosion of the blades, whereby the electrical efficiency is compromised and expensive repairs may be required. One possible solution...

  17. Vibration characteristics analysis of rotating shrouded blades with impacts

    Science.gov (United States)

    Ma, Hui; Xie, Fangtao; Nai, Haiqiang; Wen, Bangchun

    2016-09-01

    A dynamic model of rotating shrouded blades with impacts among adjacent shrouded blades is established considering the effects of the centrifugal stiffening, spin softening and Coriolis force, and the model is validated using finite element method. In the proposed model, the shrouded blade is simplified as a cantilever Euler-Bernoulli beam with a mass point at the free end, and the flexural dynamic stiffness of shrouded blade is selected as contact stiffness during collision. Based on the developed model, the effects of symmetric and asymmetric shroud gaps, rotational speeds, and aerodynamic force amplitudes on the dynamic characteristics of shrouded blades are analyzed through Newmark-β numerical method. The results indicate that (1) the vibro-impact responses of shrouded blades under some asymmetric gaps are more complicated than that under symmetric gap. (2) With the increase of rotational speed from 6000 to 10,000 rev/min, the system vibration experiences from period-three motion, through chaotic motion, finally to period-one motion during collision process because the increasing rotational speed changes the flexural dynamic stiffness of rotating blade. (3) The vibration displacements of shrouded blades increase linearly, and impact force increases linearly with the increase of aerodynamic force amplitude.

  18. Subcomponent testing of trailing edge panels in wind turbine blades

    DEFF Research Database (Denmark)

    Branner, Kim; Berring, Peter; Haselbach, Philipp Ulrich

    2016-01-01

    This paper proposes a static subcomponent test method designed to check the compressive strength of the trailing edge region in wind turbine blades under a simplified loading. The paper presents numerical simulations using the proposed subcomponent test method and discusses its ability to be used...... for checking the compressive strength of the trailing edge region in wind turbine blades....

  19. An aerodynamic performance analysis of a perforated wind turbine blade

    Science.gov (United States)

    Didane, D. H.; Mohd, S.; Subari, Z.; Rosly, N.; Ghafir, M. F. Abdul; Mohd Masrom, M. F.

    2016-11-01

    Wind power is one of the important renewable energy sources. Currently, many researches are focusing on improving the aerodynamic performance of wind turbine blades through simulations and wind tunnel testing. In the present study, the aerodynamic performance of the perforated Eqwin blade (shell type blade) is investigated by using numerical simulation. Three types of slots namely circular, horizontal rectangular and vertical rectangular were evaluated. It was found that the optimum angle of attack for a perforated shell type blade was 12° with maximum Cl/Cd value of 6.420. In general, for all the perforated blade cases, Cl/Cd tended to decrease as the slot size increased except for the circular slot with 5 mm diameter. This was due to the disturbance of the airflow in lower side region which passed through the bigger slot size. Among the modified slots; the circular slot with diameter of 5 mm would be the best slot configuration that can be considered for blade fabrication. The Cl/Cd obtained was 6.46 which is about 5% more than the value of the reference blade. Moreover, the introduced slot would also reduce the overall weight of the blade by 1.3%.

  20. Composite rotor blades for large wind energy installations

    Science.gov (United States)

    Kussmann, A.; Molly, J.; Muser, D.

    1980-01-01

    The design of large wind power systems in Germany is reviewed with attention given to elaboration of the total wind energy system, aerodynamic design of the rotor blade, and wind loading effects. Particular consideration is given to the development of composite glass fiber/plastic or carbon fiber/plastic rotor blades for such installations.

  1. Computational Fluid Dynamic Analysis of a Vibrating Turbine Blade

    Directory of Open Access Journals (Sweden)

    Osama N. Alshroof

    2012-01-01

    Full Text Available This study presents the numerical fluid-structure interaction (FSI modelling of a vibrating turbine blade using the commercial software ANSYS-12.1. The study has two major aims: (i discussion of the current state of the art of modelling FSI in gas turbine engines and (ii development of a “tuned” one-way FSI model of a vibrating turbine blade to investigate the correlation between the pressure at the turbine casing surface and the vibrating blade motion. Firstly, the feasibility of the complete FSI coupled two-way, three-dimensional modelling of a turbine blade undergoing vibration using current commercial software is discussed. Various modelling simplifications, which reduce the full coupling between the fluid and structural domains, are then presented. The one-way FSI model of the vibrating turbine blade is introduced, which has the computational efficiency of a moving boundary CFD model. This one-way FSI model includes the corrected motion of the vibrating turbine blade under given engine flow conditions. This one-way FSI model is used to interrogate the pressure around a vibrating gas turbine blade. The results obtained show that the pressure distribution at the casing surface does not differ significantly, in its general form, from the pressure at the vibrating rotor blade tip.

  2. Adaptive location of repaired blade for multi-axis milling

    Directory of Open Access Journals (Sweden)

    Baohai Wu

    2015-10-01

    Full Text Available Free-form blades are widely used in different industries, such as aero-engine and steam turbine. Blades that are damaged during service or have production deficiencies are usually replaced with new ones. This leads to the waste of expensive material and is not sustainable. However, material and costs can be saved by repairing of locally damaged blades or blades with localized production deficiencies. The blade needs to be further machined after welding process to reach the aerodynamic performance requirements. This paper outlines an adaptive location approach of repaired blade for model reconstruction and NC machining. Firstly, a mathematical model is established to describe the localization problem under constraints. Secondly, by solving the mathematical model, localization of repaired blade for NC machining can be obtained. Furthermore, a more flexible method based on the proposed mathematical model and the continuity of the deformation process is developed to realize a better localization. Thirdly, by rebuilding the model of the repaired blade and extracting repair error, optimized tool paths for NC machining is generated adaptively for each individual part. Finally, three examples are given to validate the proposed method.

  3. Teach Deflection Concepts with Hacksaw Blades and Rubber Bands

    Science.gov (United States)

    Roman, Harry T.

    2013-01-01

    Technology and engineering educators can use a simple hacksaw blade to help students learn about deflection, as that which occurs in a beam. Here the beam is fixed at one end and allowed to deflect in a manner that is easy to see and measure--the hacksaw blade represents a cantilever, an overhanging structure. This simple and very inexpensive…

  4. Development of smart blade technology - trailing edge flaps

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge

    2014-01-01

    With blade lengths presently up to 80+ m there is a need for a supplement to the standard pitch system for control of power and loads. Distributed load control along the blade span with trailing edge flaps is a promising concept where numerical simulations have shown considerable load alleviation...

  5. The Near Mallett Unit Foveal Suppression Test: a cross-sectional study to establish test norms and relationship with other optometric tests.

    Science.gov (United States)

    Tang, Sosena T W; Evans, Bruce J W

    2007-01-01

    When the binocular system comes under prolonged stress in decompensated heterophoria, a small suppression area can develop at the fovea. This foveal suppression (FS) may be an adaptation to eliminate symptoms. The near Mallett unit (NMU) is a hand-held instrument that contains a binocular status test for detecting and quantifying FS. We measured FS in a cross-sectional study of 131 patients to investigate the normal range of responses. A ratio scoring method was devised which considers the number of letters read with dichoptic viewing when binocularly fused (b) and under monocular (m) conditions, using the formula 100 x (m - b)/m. The 95th percentile value of the FS ratios was calculated as the limit of the normal range and this gave a value for the right eye (RE; 33%), left eye (LE; 43%) and total (38%). This result shows that statistically significant FS occurs when a patient can read approximately one line further in the test monocularly, compared to under fused dichoptic conditions. A statistically significant correlation was found between absolute values of horizontal aligning prism (associated heterophoria on the NMU) and FS ratio. Some limitations of the FS test and unexpected results became apparent during our research and an abnormal result on the test does not always indicate a binocular vision anomaly. Nonetheless, we feel that the test can provide useful information when the results are taken in the context of other clinical tests. Our results are used to develop recommendations and clinical guidelines for using the FS test, and to make suggestions for improvements in future designs of the test.

  6. A cross-sectional descriptive study of prevalence and nature of psychiatric referrals from intensive care units in a multispecialty hospital

    Directory of Open Access Journals (Sweden)

    Govind S Bhogale

    2011-01-01

    Full Text Available Context: The prevalence of psychiatric comorbidity in general hospital range from 20% to 60%. Presence of psychiatric morbidity compounds the disability and suffering in medical patients. There is a limited literature on the prevalence of psychiatric morbidity in patients admitted in the intensive care units (ICUs. Aims: The aim of the study was to estimate the prevalence and nature of comorbid psychiatric illness in the cases referred from ICUs. Settings and Design: Cross-sectional observational study. Materials and Methods: This study included all the consecutive patients referred from different ICUs to psychiatry department for consultation during the four-year period from January 1, 2000 to December 31, 2003, assessment was done by psychiatrist and diagnosis was made using ICD-10. Statistical Analysis: Descriptive statistics. Results: There were 309 (1.97% referrals from ICUs to psychiatry department during the period of study. Among the referred patients, diagnosis of organic mental disorders was the commonest psychiatric diagnosis present in 104 (33.65% patients followed by suicidal attempt in 101 (32.69%; anxiety disorders in 40 (12.94%; depressive disorders in 21 (6.8%; Psychotic illness in 10 (3.24%; other psychiatric illnesses in 28 (9.06%; and nil psychiatric illness in 5 (1.62% patients. Conclusion: Prevalence of psychiatric referrals from ICUs was low. This could be due to stigma and lack of awareness among physicians. There is increased need for recognition and treatment of comorbid psychiatric illness by the treating physicians which may help to decrease morbidity and overall cost of the treatment.

  7. A network model of communication in an interprofessional team of healthcare professionals: A cross-sectional study of a burn unit.

    Science.gov (United States)

    Shoham, David A; Harris, Jenine K; Mundt, Marlon; McGaghie, William

    2016-09-01

    Healthcare teams consist of individuals communicating with one another during patient care delivery. Coordination of multiple specialties is critical for patients with complex health conditions, and requires interprofessional and intraprofessional communication. We examined a communication network of 71 health professionals in four professional roles: physician, nurse, health management, and support personnel (dietitian, pharmacist, or social worker), or other health professionals (including physical, respiratory, and occupational therapists, and medical students) working in a burn unit. Data for this cross-sectional study were collected by surveying members of a healthcare team. Ties were defined by asking team members whom they discussed patient care matters with on the shift. We built an exponential random graph model to determine: (1) does professional role influence the likelihood of a tie; (2) are ties more likely between team members from different professions compared to between team members from the same profession; and (3) which professions are more likely to form interprofessional ties. Health management and support personnel ties were 94% interprofessional while ties among nurses were 60% interprofessional. Nurses and other health professionals were significantly less likely than physicians to form ties. Nurses were 1.64 times more likely to communicate with nurses than non-nurses (OR = 1.64, 95% CI: 1.01-2.66); there was no significant role homophily for physicians, other health professionals, or health management and support personnel. Understanding communication networks in healthcare teams is an early step in understanding how teams work together to provide care; future work should evaluate the types and quality of interactions between members of interprofessional healthcare teams.

  8. Acoustic emission monitoring of wind turbine blades

    Science.gov (United States)

    Van Dam, Jeremy; Bond, Leonard J.

    2015-03-01

    Damage to wind turbine blades can, if left uncorrected, evolve into catastrophic failures resulting in high costs and significant losses for the operator. Detection of damage, especially in real time, has the potential to mitigate the losses associated with such catastrophic failure. To address this need various forms of online monitoring are being investigated, including acoustic emission detection. In this paper, pencil lead breaks are used as a standard reference source and tests are performed on unidirectional glass-fiber-reinforced-polymer plates. The mechanical pencil break is used to simulate an acoustic emission (AE) that generates elastic waves in the plate. Piezoelectric sensors and a data acquisition system are used to detect and record the signals. The expected dispersion curves generated for Lamb waves in plates are calculated, and the Gabor wavelet transform is used to provide dispersion curves based on experimental data. AE sources using an aluminum plate are used as a reference case for the experimental system and data processing validation. The analysis of the composite material provides information concerning the wave speed, modes, and attenuation of the waveform, which can be used to estimate maximum AE event - receiver separation, in a particular geometry and materials combination. The foundational data provided in this paper help to guide improvements in online structural health monitoring of wind turbine blades using acoustic emission.

  9. Investigation of Structural Behavior due to Bend-Twist Couplings in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Fedorov, Vladimir; Dimitrov, Nikolay Krasimirov; Berggreen, Christian

    2010-01-01

    work attention was aimed specifically at shell element based FEA models for predicting torsional behaviour of the blade. Three models were developed in different codes: An ANSYS and ABAQUS model with standard section input and an ANSYS model with matrix input. All models employed the outer surface...... in torsion with deviations in the range of 15 to 35%, when employing the section input for the off-set definition. However, the ANSYS model generated using matrix input for the off-set definition was found to perform adequately....

  10. Ultimate Strength of Wind Turbine Blades under Multiaxial Loading

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich

    loading effects and its influence on the ultimate strength of typical wind turbine rotor blade structures and to develop methods to perform reliable prediction of failure. For this purpose, origin and consequence of some of the typically occurring failure types in wind turbine rotor blades...... the ultimate strength of wind turbine rotor blades under multiaxial loadings. Failure origin and effects are studied numerically and experimentally with the purpose to investigate root causes of blade failure and to find generalities for their origin. The main contributions from this PhD study covering...... criteria are studied and their limitations demonstrated by comparing numerical and experimental results of a full scale blade loaded to ultimate failure. The main contributions from this PhD thesis dealing with failure origin and effects are the determination of generalities of failure. For buckling driven...

  11. Reliability-based design of wind turbine blades

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2011-01-01

    Reliability-based design of wind turbine blades requires identification of the important failure modes/limit states along with stochastic models for the uncertainties and methods for estimating the reliability. In the present paper it is described how reliability-based design can be applied to wind...... turbine blades. For wind turbine blades, tests with the basic composite materials and a few full-scale blades are normally performed during the design process. By adopting a reliability-based design approach, information from these tests can be taken into account in a rational way during the design...... process. In the present paper, a probabilistic framework for design of wind turbine blades are presented and it is demonstrated how information from tests can be taken into account using the Maximum-Likelihood method and Bayesian statistics. In a numerical example, the reliability is estimated for a wind...

  12. Effects of aerodynamic fairing on full scale blade fatigue test

    Science.gov (United States)

    Pan, Zujin; Wu, Jianzhong; Sun, Yuanrong; Jian, Liu

    2017-06-01

    The reliability of large blades should be verified by means of full scale fatigue test. In order to solve the problem of lack of exciting force during fatigue test in the flap wise direction, the program that aerodynamic fairing is installed in the tip of blade to reduce the air resistance is proposed. The numerical model of blade vibration and damping ratio calculation is established. The relationship between damping ratio, exciting force and amplitude is constructed by finite element method respectively. The difference of the exciting bending moment of blade and the damping ratio before and after the installation of aerodynamic fairing is compared respectively. The results show that damping ratio decreased by 27.9%. When the vibration of the blade reaches the target bending moment, the exciting force of the equipment decreases by 45.4%. It is an effective way to reduce the exciting force.

  13. Research on algorithm of blade vibration for general wind turbine

    Science.gov (United States)

    Wang, Long; Sun, Lun-ye; Wu, Guang; Li, Xue-bin; Lai, Yong-bin; Zhou, Yi-jun

    2016-01-01

    Evaluation of vibration characteristics for wind turbine blades is one of the important contents in the wind turbine research. This paper uses the compressible flow equations with the preconditioning technique, based on the finite volume method and combined with the LU-SGS algorithm for solving the flow area; meanwhile adopts the two degree of freedom of vibration equation with the vertical and torsional vibration for blades to simulate the vibration trajectory of blade under the aerodynamic force, uses the motion grid algorithm for changes in grid computing domain. Calculation program was developed autonomous in the C ++ platform, and the development of software correctness was verified by contrast the results of the classic cylindrical examples. Finally, the vibration characteristics of a wind turbine blade was given, and the software developed in this paper can provide technical support for wind turbine blade vibration study.

  14. Wind turbine blade testing system using base excitation

    Science.gov (United States)

    Cotrell, Jason; Thresher, Robert; Lambert, Scott; Hughes, Scott; Johnson, Jay

    2014-03-25

    An apparatus (500) for fatigue testing elongate test articles (404) including wind turbine blades through forced or resonant excitation of the base (406) of the test articles (404). The apparatus (500) includes a testing platform or foundation (402). A blade support (410) is provided for retaining or supporting a base (406) of an elongate test article (404), and the blade support (410) is pivotally mounted on the testing platform (402) with at least two degrees of freedom of motion relative to the testing platform (402). An excitation input assembly (540) is interconnected with the blade support (410) and includes first and second actuators (444, 446, 541) that act to concurrently apply forces or loads to the blade support (410). The actuator forces are cyclically applied in first and second transverse directions. The test article (404) responds to shaking of its base (406) by oscillating in two, transverse directions (505, 507).

  15. Reliability-based design of wind turbine blades

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2011-01-01

    Reliability-based design of wind turbine blades requires identification of the important failure modes/limit states along with stochastic models for the uncertainties and methods for estimating the reliability. In the present paper it is described how reliability-based design can be applied to wind...... turbine blades. For wind turbine blades, tests with the basic composite materials and a few full-scale blades are normally performed during the design process. By adopting a reliability-based design approach, information from these tests can be taken into account in a rational way during the design...... process. In the present paper, a probabilistic framework for design of wind turbine blades are presented and it is demonstrated how information from tests can be taken into account using the Maximum-Likelihood method and Bayesian statistics. In a numerical example, the reliability is estimated for a wind...

  16. Aerodynamic investigation of winglets on wind turbine blades using CFD

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Sørensen, Niels N.

    2006-01-01

    The present report describes the numerical investigation of the aerodynamics around a wind turbine blade with a winglet using Computational Fluid Dynamics, CFD. Five winglets were investigated with different twist distribution and camber. Four of them were pointing towards the pressure side...... (upstream) and one was pointing towards the suction side (downstream). Additionally, a rectangular modification of the original blade tip was designed with the same planform area as the blades with winglets. Results show that adding a winglet to the existing blade increase the force distribution...... on the outer approx 14 % of the blade leading to increased produced power of around 0.6% to 1.4% for wind speeds larger than 6 m/s. This has to be compared to the increase in thrust of around 1.0% to 1.6%. Pointing the winglet downstream increases the power production even further. The effect of sweep and cant...

  17. A Long-Period Grating Sensor for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Glavind, Lars

    This PhD project concerns the applied research for providing a novel sensor for measurements on wind turbine blades, based on Long-Period Gratings. The idea is based on the utilization of a special asymmetrical optical fibre with Long-Period Gratings for directional sensitive bend sensing....... The project involves the processes from feasibility study of fibre grating technology to full scale test on a wind turbine blade. The project has involved the design and manufacturing of a D-shape optical fibre. The project includes the process of embedding the optical fibre directly into the wind turbine...... blade material, where a suitable process and recoating material were investigated. The sensor was implemented and tested on a full scale wind turbine blade placed on a test rig. This first prototype has demonstrated the capability of the sensor for wind turbine blade monitoring, particular...

  18. Non-linear dynamic response of a wind turbine blade

    Science.gov (United States)

    Chopra, I.; Dugundji, J.

    1979-01-01

    The paper outlines the nonlinear dynamic analysis of an isolated three-degree flap-lag-feather wind turbine blade under a gravity field and with shear flow. Lagrangian equations are used to derive the nonlinear equations of motion of blade for arbitrarily large angular deflections. The limit cycle analysis for forced oscillations and the determination of the principal parametric resonance of the blade due to periodic forces from the gravity field and wind shear are performed using the harmonic balance method. Results are obtained first for a two-degree flap-lag blade, then the effect of the third degree of freedom (feather) is studied. The self-excited flutter solutions are obtained for a uniform wind and with gravity forces neglected. The effects of several parameters on the blade stability are examined, including coning angle, structural damping, Lock number, and feather frequency. The limit cycle flutter solution of a typical configuration shows a substantial nonlinear softening spring behavior.

  19. Modeling of uncertainties for wind turbine blade design

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Toft, Henrik Stensgaard

    2014-01-01

    Wind turbine blades are designed by a combination of tests and numerical calculations using finite element models of the blade. The blades are typically composite structures with laminates of glass-fiber and/or carbon-fibers glued together by a matrix material. This paper presents a framework...... for stochastic modelling of the load bearing capacity of wind turbine blades incorporating physical, model, measurement and statistical uncertainties at the different scales and also discusses the possibility to define numerical tests that can be included in the statistical basis. The stochastic modelling takes...... basis in the JCSS framework for modelling material properties, Bayesian statistical methods allowing prior / expert knowledge to be accounted for and the Maximum Likelihood Method. The stochastic framework is illustrated using simulated tests which represent examples relevant for wind turbine blades....

  20. Blade Bearing Friction Estimation of Operating Wind Turbines

    DEFF Research Database (Denmark)

    Perisic, Nevena; Pedersen, Bo Juul; Kirkegaard, Poul Henning

    2012-01-01

    Blade root bearing on a wind turbine (WTG) enables pitching of blades for power control and rotor braking and is a WTG critical component. As the size of modern WTGs is constantly increasing, this leads to relatively less rigid bearings, more sensitive to deformations, thus WTG operational...... reliability can be increased by continuous monitoring of blade bearing. High blade bearing friction is undesirable, as it may be associated with excessive heating of the surfaces, damage and/or inefficient operation. Thus, continuous observation of bearing friction level is crucial for blade bearing health...... monitoring systems. A novel algorithm for online monitoring of bearing friction level is developed combining physical knowledge about pitch system dynamics with state estimator, i.e. observer theory and signal processing assuming realistic sensor availability. Results show estimation of bearing friction...