WorldWideScience

Sample records for blade loading

  1. 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.

  2. 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....

  3. Load attenuating passively adaptive wind turbine blade

    Science.gov (United States)

    Veers, Paul S.; Lobitz, Donald W.

    2003-01-07

    A method and apparatus for improving wind turbine performance by alleviating loads and controlling the rotor. The invention employs the use of a passively adaptive blade that senses the wind velocity or rotational speed, and accordingly modifies its aerodynamic configuration. The invention exploits the load mitigation prospects of a blade that twists toward feather as it bends. The invention includes passively adaptive wind turbine rotors or blades with currently preferred power control features. The apparatus is a composite fiber horizontal axis wind-turbine blade, in which a substantial majority of fibers in the blade skin are inclined at angles of between 15 and 30 degrees to the axis of the blade, to produces passive adaptive aeroelastic tailoring (bend-twist coupling) to alleviate loading without unduly jeopardizing performance.

  4. Full Scale Test SSP 34m blade, Combined load. Data report

    DEFF Research Database (Denmark)

    Nielsen, Per Hørlyk; Nielsen, Magda; Jensen, Find Mølholt

    This report is part of the research project entitled “Eksperimentel vingeforskning: Strukturelle mekanismer i nutidens og fremtidens store vinger under kombineret last” where a 34m wind turbine blade from SSP-Technology A/S was tested in combined flap and edgewise load. The applied load is 55......% of an imaginary extreme event based on the certification load of the blade. This report describes the reason for choosing the loads and the load direction and the method of applying the loads to the blade. A novel load introduction allows the blade to deform in a more realistic manner, allowing the observation...

  5. Full scale test SSP 34m blade, combined load. Data report

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Per H.; Nielsen, Magda; Jensen, Find M. (and others)

    2010-11-15

    This report is part of the research project where a 34m wind turbine blade from SSP-Technology A/S was tested in combined flap and edgewise load. The applied load is 55% of an imaginary extreme event based on the certification load of the blade. This report describes the reason for choosing the loads and the load direction and the method of applying the loads to the blade. A novel load introduction allows the blade to deform in a more realistic manner, allowing the observation of e.g. transverse shear distortion. The global and local deformation of the blade as well as the blades' respond to repeated tests has been studied and the result from these investigations are presented, including the measurements performed. (Author)

  6. Structural investigation of composite wind turbine blade considering various load cases and fatigue life

    International Nuclear Information System (INIS)

    Kong, C.; Bang, J.; Sugiyama, Y.

    2005-01-01

    This study proposes a structural design for developing a medium scale composite wind turbine blade made of E-glass/epoxy for a 750 kW class horizontal axis wind turbine system. The design loads were determined from various load cases specified at the IEC61400-1 international specification and GL regulations for the wind energy conversion system. A specific composite structure configuration, which can effectively endure various loads such as aerodynamic loads and loads due to accumulation of ice, hygro-thermal and mechanical loads, was proposed. To evaluate the proposed composite wind turbine blade, structural analysis was performed by using the finite element method. Parametric studies were carried out to determine an acceptable blade structural design, and the most dominant design parameters were confirmed. In this study, the proposed blade structure was confirmed to be safe and stable under various load conditions, including the extreme load conditions. Moreover, the blade adapted a new blade root joint with insert bolts, and its safety was verified at design loads including fatigue loads. The fatigue life of a blade that has to endure for more than 20 years was estimated by using the well-known S-N linear damage theory, the service load spectrum, and the Spera's empirical equations. With the results obtained from all the structural design and analysis, prototype composite blades were manufactured. A specific construction process including the lay-up molding method was applied to manufacturing blades. Full-scale static structural test was performed with the simulated aerodynamic loads. From the experimental results, it was found that the designed blade had structural integrity. In addition, the measured results of deflections, strains, mass, and radial center of gravity agreed well with the analytical results. The prototype blade was successfully certified by an international certification institute, GL (Germanisher Lloyd) in Germany

  7. 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.

  8. Full Scale Test SSP 34m blade, edgewise loading LTT. Extreme load and PoC_InvE Data report

    DEFF Research Database (Denmark)

    Nielsen, Magda; Roczek-Sieradzan, Agnieszka; Jensen, Find Mølholt

    in edgewise direction (LTT). The blade has been submitted to thorough examination by means of strain gauges, displacement transducers and a 3D optical measuring system. This data report presents results obtained during full scale testing of the blade up to 80% Risø load, where 80% Risø load corresponds to 100...

  9. Full scale testing of wind turbine blade to failure - flapwise loading

    DEFF Research Database (Denmark)

    Jørgensen, E.R.; Borum, Kaj Kvisgaard; McGugan, Malcolm

    2004-01-01

    for the detection of damages in the blade during the test. The report contains measurements of the total deflection of the blade, the local deflection of the skinand the load carrying main spar and also measurement of strain all as a function of the applied load and up to failure of the blade. The “post mortem......” analysis and description of how the damages propagate du-ring the tests are reported in a separatereport....

  10. Loadings in thermal barrier coatings of jet engine turbine blades an experimental research and numerical modeling

    CERN Document Server

    Sadowski, Tomasz

    2016-01-01

    This book discusses complex loadings of turbine blades and protective layer Thermal Barrier Coating (TBC), under real working airplane jet conditions. They obey both multi-axial mechanical loading and sudden temperature variation during starting and landing of the airplanes. In particular, two types of blades are analyzed: stationary and rotating, which are widely applied in turbine engines produced by airplane factories.

  11. Controller Design for Blade Load Reduction Using Synthetic Jets

    DEFF Research Database (Denmark)

    Soltani, Mohsen; Mirzaei, Mahmood

    2014-01-01

    actuators to damp structural vibration. This paper, presents the design of a control system that acts on blade synthetic jets to reduce and damp the vibration of the desired blade modes. The design of model-based estimators is addressed. These estimators use the measurements of several accelerometers...... and strain gauges along the blade and the tower to estimate the contribution of each blade modal state to the vibration of the tower and the blades. The synthetic jet actuators are then controlled, such that the desired vibration modes are damped effectively. Designed estimator and controller are implemented...

  12. Calibration procedures for improved accuracy of wind turbine blade load measurement

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Johansson, Hjalmar [Teknikgruppen AB, Sollentuna (Sweden)

    1996-12-01

    External loads acting on wind turbine blades are mainly transferred via the hub to the rest of the structure. It is therefore a normal approach to measure the loads acting on the turbine by load measurements in the blade roots. The load measurement is often accomplished by measurements of strain on the surface of the blade or the hub. The strain signals are converted to loads by applying calibration factors to the measurements. This paper deals with difficulties associated with load measurements on two different wind turbines; one with strain gauges applied to a steel hub where a linear stress-load relationship is expected and the other with strain gauges applied to the GFRP blade close to the bearings where strong non-linearity`s and temperature effects are expected. This paper suggests calibration methods to overcome these problems. 2 refs, 11 figs

  13. Material matters: Controllable rubber trailing edge flap regulates load on wind turbine blades

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge

    2010-01-01

    trailing edge flap, known as CRTEF. The trailing edge blade design is expected to help mitigate localized loading, and its molded rubber design, the sharp trailing edge, produces less noise and greater output. With CRTEF, the blade automatically has a completely sharp edge. The elastic flap tested...

  14. A simplified model predicting the weight of the load carrying beam in a wind turbine blade

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    2016-01-01

    Based on a simplified beam model, the loads, stresses and deflections experienced by a wind turbine blade of a given length is estimated. Due to the simplicity of the model used, the model is well suited for work investigating scaling effects of wind turbine blades. Presently, the model is used t...

  15. Modelling of Vortex-Induced Loading on a Single-Blade Installation Setup

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac; Heinz, Joachim Christian

    2016-01-01

    Vortex-induced integral loading fluctuations on a single suspended blade at various inflow angles were modeled in the presents work by means of stochastic modelling methods. The reference time series were obtained by 3D DES CFD computations carried out on the DTU 10MW reference wind turbine blade...

  16. Effect of blade flutter and electrical loading on small wind turbine noise

    Science.gov (United States)

    The effect of blade flutter and electrical loading on the noise level of two different size wind turbines was investigated at the Conservation and Production Research Laboratory (CPRL) near Bushland, TX. Noise and performance data were collected on two blade designs tested on a wind turbine rated a...

  17. Load consequences when sweeping blades - A case study of a 5 MW pitch controlled wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Verelst, D.R.S.; Larsen, Torben J.

    2010-08-15

    The generic 5 MW NREL wind turbine model is used in Risoe's aeroelastic simulator HAWC2 to investigate 120 different swept blade configurations (forward and backward sweep). Sensitivity for 2 different controllers is considered as well. Backward sweep results in a pitch to feather torsional moment of the blade, effectively reducing blade twist angles under increased loading. This behaviour results in decreased flap-wise fatigue and extreme loads, an increase for edge-wise fatigue loading and status quo or slight decrease in extreme loads (depending on the controller). Tower base and shaft-end bending moments are reduced as well. Forward sweep leads to an increase in angle of attack under loading. For a pitch controlled turbine this leads to an increase in fatigue and extreme loading in all cases. A controller inflicted instability is present for the more extreme forward swept cases. Due to the shape of considered sweep curves, an inherent and significant increase in torsional blade root bending moment is noted. A boomerang shaped sweep curve is proposed to counteract this problematic increased loading. Controller sensitivity shows that adding sweep affects some loadings differently. Power output is reduced for backward sweep since the blade twist is optimized as a rigid structure, ignoring the torsional deformations which for a swept blade can be significant. (author)

  18. Influence of Thermodynamic Effect on Blade Load in a Cavitating Inducer

    Directory of Open Access Journals (Sweden)

    Kengo Kikuta

    2010-01-01

    Full Text Available Distribution of the blade load is one of the design parameters for a cavitating inducer. For experimental investigation of the thermodynamic effect on the blade load, we conducted experiments in both cold water and liquid nitrogen. The thermodynamic effect on cavitation notably appears in this cryogenic fluid although it can be disregarded in cold water. In these experiments, the pressure rise along the blade tip was measured. In water, the pressure increased almost linearly from the leading edge to the trailing edge at higher cavitation number. After that, with a decrease of cavitation number, pressure rise occurred only near the trailing edge. On the other hand, in liquid nitrogen, the pressure distribution was similar to that in water at a higher cavitation number, even if the cavitation number as a cavitation parameter decreased. Because the cavitation growth is suppressed by the thermodynamic effect, the distribution of the blade load does not change even at lower cavitation number. By contrast, the pressure distribution in liquid nitrogen has the same tendency as that in water if the cavity length at the blade tip is taken as a cavitation indication. From these results, it was found that the shift of the blade load to the trailing edge depended on the increase of cavity length, and that the distribution of blade load was indicated only by the cavity length independent of the thermodynamic effect.

  19. Investigation of potential extreme load reduction for a two-bladed upwind turbine with partial pitch

    DEFF Research Database (Denmark)

    Kim, Taeseong; Larsen, Torben J.; Yde, Anders

    2015-01-01

    This paper presents a wind turbine concept with an innovative design combining partial pitch with a two-bladed (PP-2B) turbine configuration. Special emphasis is on extreme load reduction during storm situations at standstill, but operational loads are also investigated. In order to compare...... the loads and dynamics of the PP-2B turbine, a partial pitch three-bladed (PP-3B) turbine and a normal pitch regulated three-bladed (3B) turbine are introduced on the basis of solidity similarity scaling. From the dynamic comparisons between two- and three-bladed turbines, it has been observed...... that the blade vibrations are transferred differently from the rotor to the tower. For a three-bladed turbine, blade vibrations seen in a fixed frame of reference are split with ±1P only. A two-bladed turbine has a similar split of ±1P but also includes contributions on higher harmonics (±2P, ±3P, … etc...

  20. Extreme Design Loads Calibration of Offshore Wind Turbine Blades through Real Time Measurements

    DEFF Research Database (Denmark)

    Natarajan, Anand; Vesth, Allan; Lamata, Rebeca Rivera

    2014-01-01

    moment is extrapolated. This is found to possess smaller scaling factors in measurements over six months as compared to both the flap and edge moments, indicating that the contemporaneous load component of an extrapolated load should possess much smaller magnitude than its maxima.......Blade Root flap and Edge moments are measured on the blades of a 3.6MW offshore wind turbine in normal operation. Ten minute maxima of the measurements are sampled to determine the extreme blade root flap moment, edge moment and resultant moment over six month duration. A random subset...... root flap moment, edge moment obtained by extrapolation. The validation yields valuable information on prescribing the slope of the local extrapolation curve at each mean wind speed. As an alternative to determining the contemporaneous loads for each primary extrapolated load, the blade root resultant...

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

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    2006-01-01

    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, and tor......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......, 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...

  2. Use of the WEST-1 wind turbine simulator to predict blade fatigue load distribution

    Science.gov (United States)

    Janetzke, D. C.

    1983-01-01

    To test the ability of WEST-1 to predict blade fatigue load distribution, actual wind signals were fed into the simulator and the response data were recorded and processed in the same manner as actual wind turbine data. The WEST-1 simulator was operated in a stable, unattended mode for six hours. The probability distribution of the cyclic flatwise bending moment for the blade was comparable to that for an actual wind turbine in winds with low turbulence. The input from a stationary anemometer was found to be inadequate for use in the prediction of fatigue load distribution for blade design purposes and modifications are necessary.

  3. Influence of loading distribution on the performance of high pressure turbine blades

    Science.gov (United States)

    Corriveau, Daniel

    Midspan measurements were made in a transonic wind tunnel for three High Pressure (HP) turbine blade cascades at both design and off-design incidences. Comparisons with two-dimensional numerical simulations of the cascade flow were also made. The baseline profile is the midspan section of a HP turbine blade of fairly recent design. It is considered mid-loaded. To gain a better understanding of blade loading limits and the influence of loading distributions, the profile of the baseline airfoil was modified to create two new airfoils having aft-loaded and front-loaded pressure distributions. Tests were performed for exit Mach numbers between 0.6 and 1.2. In addition, measurements were made for an extended range of Reynolds numbers for constant Mach numbers of 0.6, 0.85, 0.95 and 1.05. At the design exit Mach number of 1.05 and at design incidence, the aft-loaded airfoil showed a reduction of almost 20% in the total pressure losses compared with the baseline airfoil. Based on the analysis of wake traverse data and base pressure measurements combined with numerical results, it was found that the poorer loss performance of the baseline mid-loaded profile compared to the aft-loaded blade could be attributed to the former's higher rear suction side curvature, which resulted in higher flow velocity in that region, which, in turn, contributed to reducing the base pressure. The lower base pressure at the trailing edge resulted in a stronger trailing edge shock system for the mid-loaded blade. This shock system increased the losses for the mid-loaded baseline profile when compared to the aft-loaded profile. On the negative side, it was also found that as Mach numbers were increased beyond the design value the performance of the aft-loaded blade deteriorated rapidly. Under such conditions, the front-loaded airfoil showed generally inferior performance compared with the baseline airfoil. At off-design incidence, the aft-loaded blade maintained a superior loss performance over a

  4. Immediately loaded blade implant retrieved from a after a 20-year loading period: a histologic and histomorphometric case report.

    Science.gov (United States)

    Di Stefano, Danilo; Iezzi, Giovanna; Scarano, Antonio; Perrotti, Vittoria; Piattelli, Adriano

    2006-01-01

    Immediate loading of root-form dental implants has shown promising results and offers treatment cost and convenience advantages to patients. Although blade implants have been immediately loaded for over 2 decades, the ability of this implant design to achieve osseointegration has been debated. The aim of the present study was to histologically evaluate the peri-implant tissues of an immediately loaded blade implant retrieved for abutment fracture after a 20-year loading period. Histologic samples were prepared and examined by light microscope. Compact, cortical, mature bone with well-formed osteons was present at the interface of the implant. Bone-to-implant contact was 51% +/- 6%. The histologic data showed that osseointegration was obtained in an immediately loaded blade implant inserted into the mandible, and that mineralized tissues were maintained at the interface over a long period (20 years).

  5. Active load reduction using individual pitch, based on local blade flow measurements

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Aagaard Madsen, H.; Thomsen, K.

    2005-01-01

    -of-the-art load-reducing concepts. Since the new flow-based concept deviates significantly from previous published load-reducing strategies, a comparison of the performance based on aeroelastic simulations is included. Advantages and drawbacks of the systems are discussed. Copyright (C) 2004 John Wiley Sons, Ltd.......A new load-reducing control strategy for individual blade control of large pitch-controlled wind turbines is presented This control concept is based on local blade inflow measurements and offers the possibility of larger load reductions, without loss of power production, than seen in other state...

  6. Immediately loaded blade implants. a histological and histomorphometrical evaluation after a long loading period. a retrospective 20 years analysis (1989-2009)

    OpenAIRE

    Giovanna Iezzi; Antonio Scarano; Vittoria Perrotti; Domenico Tripodi; Adriano Piattelli

    2012-01-01

    Aim: Although the presence of mineralized tissues at the interface with blade implants has been reported, the view that blade implants cannot integrate still persists. Blades are the immediately loaded implants with the longest clinical history, so their histological evaluation may give results applicable to root-form implants. The aim of the present retrospective study was a histological evaluation of the peri-implant tissues in immediately loaded human blade implants retrieved after a long ...

  7. Blade design loads on the flow exciting force in centrifugal pump

    International Nuclear Information System (INIS)

    Xu, Y; Yang, A L; Langand, D P; Dai, R

    2012-01-01

    The three-dimensional viscous flow field of two centrifugal pumps, which have the same volute, design head, design flow rate and rotational speed but the blade design load, are analyzed based on large eddy simulation. The comparisons are implemented including the hydraulic efficiencies, flow field characteristics, pressure pulsations and unsteady forces applied on the impellers to investigate the effect of the design blade load on hydraulic performance and flow exciting force. The numerical results show that the efficiency of the pump, the impeller blade of which has larger design load, is improved by 1.1%∼2.9% compared to the centrifugal pump with lower blade design load. The pressure fluctuation of the pump with high design load is more remarkable. Its maximum amplitude of coefficient of static pressure is higher by 43% than the latter. At the same time the amplitude of unsteady radial force is increased by 11.6% in the time domain. The results also imply that the blade design load is an important factor on the excitation force in centrifugal pumps.

  8. A zero torsional stiffness twist morphing blade as a wind turbine load alleviation device

    International Nuclear Information System (INIS)

    Lachenal, X; Daynes, S; Weaver, P M

    2013-01-01

    This paper presents the design, analysis and realization of a zero stiffness twist morphing wind turbine blade. The morphing blade is designed to actively twist as a means of alleviating the gust loads which reduce the fatigue life of wind turbine blades. The morphing structure exploits an elastic strain energy balance within the blade to enable large twisting deformations with modest actuation requirements. While twist is introduced using the warping of the blade skin, internal pre-stressed members ensure that a constant strain energy balance is achieved throughout the deformation, resulting in a zero torsional stiffness structure. The torsional stability of the morphing blade is characterized by analysing the elastic strain energy in the device. Analytical models of the skin, the pre-stressed components and the complete blade are compared to their respective finite element models as well as experimental results. The load alleviation potential of the adaptive structure is quantified using a two-dimensional steady flow aerodynamic model which is experimentally validated with wind tunnel measurements. (paper)

  9. A Two-Bladed Teetering Hub configuration for the DTU 10 MW RWT: loads considerations

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Aagaard Madsen, Helge; Rasmussen, Flemming

    2014-01-01

    As the size of wind turbine rotors continuously grows, the need for innovative solutions that would yield to lighter rotor configurations becomes more urgent. Traditional wind turbine designs have favored the classic three-bladed upwind rotor configuration. This work presents instead a concept......, and the rotor solidity is kept constant by increasing the blade chord by 50 %. The configuration allows saving 30 % of the rotor weight and material, corresponding to one blade, but implies several complications: lower power output due to increased tip losses effects, and increased load variations. The increase...

  10. Evaluation of MOSTAS computer code for predicting dynamic loads in two-bladed wind turbines

    Science.gov (United States)

    Kaza, K. R. V.; Janetzke, D. C.; Sullivan, T. L.

    1979-01-01

    Calculated dynamic blade loads are compared with measured loads over a range of yaw stiffnesses of the DOE/NASA Mod-0 wind turbine to evaluate the performance of two versions of the MOSTAS computer code. The first version uses a time-averaged coefficient approximation in conjunction with a multiblade coordinate transformation for two-bladed rotors to solve the equations of motion by standard eigenanalysis. The results obtained with this approximate analysis do not agree with dynamic blade load amplifications at or close to resonance conditions. The results of the second version, which accounts for periodic coefficients while solving the equations by a time history integration, compare well with the measured data.

  11. Flow performance of highly loaded axial fan with bowed rotor blades

    Science.gov (United States)

    Chen, L.; Liu, X. J.; Yang, A. L.; Dai, R.

    2013-12-01

    In this paper, a partial bowed rotor blade was proposed for a newly designed high loaded axial fan. The blade was positively bowed 30 degrees from hub to 30 percent spanwise position. Flows of radial blade and bowed blade fans were numerically compared for various operation conditions. Results show that the fan's performance is improved. At the designed condition with flow coefficient of 0.52, the efficiency of the bowed blade fan is increased 1.44% and the static pressure rise is increased 11%. Comparing the flow structures, it can be found that the separated flow in the bowed fan is reduced and confined within 20 percent span, which is less than the 35 percent in the radial fan. It means that the bowed blade generates negative blade force and counteracts partial centrifugal force. It is alleviates the radial movements of boundary layers in fan's hub region. Flow losses due to 3D mixing are reduced in the rotor. Inlet flow to downstream stator is also improved.

  12. EFFECTS OF SLOTTED BLADING ON SECONDARY FLOW IN HIGHLY LOADED COMPRESSOR CASCADE

    Directory of Open Access Journals (Sweden)

    RAMZI MDOUKI

    2013-10-01

    Full Text Available With the aim to increase allowable blade loadings and enlarge stable operating range in highly loaded compressor, this work is carried out in order to explore the potential of passive control via slotted bladings in linear cascade configurations under both design and stall conditions. Through an extensive 2D-numerical study, the effects of location, width and slope of slots were analysed and the best configuration was identified. Based on the optimal slot, the 3D aerodynamic performances of cascade were studied and the influence of slotted blading to control endwall flow was investigated. Both 2D and 3D calculations are performed on steady RANS solver with standard k-epsilon turbulence model and low Mach number regime. The total loss coefficient, turning angle and flow visualizations on the blade and end-wall surfaces are adopted to describe the different configurations. The obtained results show, for 2D situation, that a maximum of 28.3% reduction in loss coefficient had been reached and the flow turning was increased with approximately 5°. Concerning 3D flow fields the slots marked their benefit at large incoming flow angles which delays the separation on both end wall and blade suction surface at mid span. However, at design conditions, the slotted blades are not able to control secondary flows near the wall and so, lose their potential.

  13. Ultimate Strength of Wind Turbine Blades under Multiaxial Loading

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich

    Modern wind turbine rotor blades are sophisticated lightweight structures, optimised towards achieving the best compromise between aerodynamic and structural design as well as a cost efficient manufacturing processes. They are usually designed for a lifetime of minimum 20 years, where they must...... endure a variety of weather conditions including uncontrollable, extreme winds without developing damage and fracture. The trend in the development of wind turbines is towards larger, more efficient wind turbines, placed offshore, where access is difficult and repairs costly. In consequence, failures...

  14. Load alleviation on wind turbine blades using variable geometry

    DEFF Research Database (Denmark)

    Basualdo, Santiago

    2005-01-01

    ) 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....

  15. Evaluation of MOSTAS computer code for predicting dynamic loads in two bladed wind turbines

    Science.gov (United States)

    Kaza, K. R. V.; Janetzke, D. C.; Sullivan, T. L.

    1979-01-01

    Calculated dynamic blade loads were compared with measured loads over a range of yaw stiffnesses of the DOE/NASA Mod-O wind turbine to evaluate the performance of two versions of the MOSTAS computer code. The first version uses a time-averaged coefficient approximation in conjunction with a multi-blade coordinate transformation for two bladed rotors to solve the equations of motion by standard eigenanalysis. The second version accounts for periodic coefficients while solving the equations by a time history integration. A hypothetical three-degree of freedom dynamic model was investigated. The exact equations of motion of this model were solved using the Floquet-Lipunov method. The equations with time-averaged coefficients were solved by standard eigenanalysis.

  16. 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

    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 materia...

  17. Analysis, Validation, Prediction And Fundamental Understanding Of Rotor Blade Loads In An Unsteady Maneuver

    Science.gov (United States)

    Abhishek, Abhishek

    This study predicts, analyzes, and isolates the mechanisms of main rotor airloads, structural loads, and swashplate servo loads in a severe unsteady maneuver. The objective is, to develop a comprehensive transient rotor analysis for predicting maneuver loads. The main rotor structural loads encountered during unsteady maneuvers are important to size different critical components of the rotor system, particularly for advanced combat helicopters. These include the blade structural loads, control/pitch-link loads, and swashplate servo loads. Accurate and consistent prediction of maneuver loads is necessary to reduce the risks and costs associated with use of prior flight test data as a basis for design. The mechanism of rotor loads in different level flight regimes is well understood -- transonic shock in high speed flight, inter-twinning of blade tip vortices below the rotor disk at low speed transonic flight, and two dynamic stall cycles on retreating blade during high altitude dynamic stall flight. All these physical phenomena can occur simultaneously during a maneuver. The goal is to understand the key mechanisms involved in maneuver and model them accurately. To achieve this, the aerodynamics and structural dynamics of UH-60A rotor in unsteady maneuvering flight is studied separately. For identification of prediction deficiencies in each, first, the measured lift, drag, pitching moment and damper force from the UH-60A Flight Test Program for UTTAS pull-up maneuver (C11029: 2.16g pull-up maneuver) are used to obtain an accurate set of deformations. A multibody finite element blade model, developed for this purpose, is used to perform measured airloads analysis. Next, the resultant blade deformations are used to predict the airloads using lifting-line and RANS CFD aerodynamic models. Both lifting-line as well as CFD analyses predict all three stall cycles with prescribed deformations. From the airloads predicted using prescribed deformations, it is established that

  18. Comparison of blade loads of fixed and free yawing wind turbine

    Science.gov (United States)

    Cheney, M. C.; Bielawa, R. L.

    1978-01-01

    The self regulating composite bearingless wind turbine utilizes an automatic pitch control concept and a completely unrestrained yawing degree of freedom. Aerodynamic moments caused by skewed flow provide the control to align the wind turbine with the wind. Model tests demonstrated the feasibility of the concept and analytical studies showed the free system to experience lower blade loads compared to the fixed system.

  19. Blade-Pitch Control for Wind Turbine Load Reductions

    DEFF Research Database (Denmark)

    Lio, Alan Wai Hou

    Large wind turbines are subjected to the harmful loads that arise from the spatially uneven and temporally unsteady oncoming wind. Such loads are the known sources of fatigue damage that reduce the turbine operational lifetime, ultimately increasing the cost of wind energy to the end-users. In re...

  20. Full Scale Test of SSP 34m blade, edgewise loading LTT

    DEFF Research Database (Denmark)

    Nielsen, Magda; Jensen, Find Mølholt; Nielsen, Per Hørlyk

    load areas. The global deflection is compared with results from a previous test and results from FEM analyses in order to validate the solution as to how the gravity load on the blade was handled. Furthermore, the DIC measurement and the displacement sensors measurements are compared in order...... to validate the results from the DIC measurements. The report includes the results from the test and a description of the measurement equipment and the data acquisition....

  1. Beamstrahlung Photon Load on the TESLA Extraction Septum Blade(LCC-0104)

    Energy Technology Data Exchange (ETDEWEB)

    Seryi, A

    2003-10-02

    This note describes work performed in the framework of the International Linear Collider Technical Review Committee [1] to estimate the power load on the TESLA extraction septum blade due to beamstrahlung photons. It is shown, that under realistic conditions the photon load can be several orders of magnitude higher than what was estimated in the TESLA TDR [2] for the ideal Gaussian beams, potentially representing a serious limitation of the current design.

  2. Computer subroutine for estimating aerodynamic blade loads on Darrieus vertical axis wind turbines. [FORCE code

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, W. N.; Leonard, T. M.

    1980-11-01

    An important aspect of structural design of the Darrieus rotor is the determination of aerodynamic blade loads. This report describes a load generator which has been used at Sandia for quasi-static and dynamic rotor analyses. The generator is based on the single streamtube aerodynamic flow model and is constructed as a FORTRAN IV subroutine to facilitate its use in finite element structural models. Input and output characteristics of the subroutine are described and a complete listing is attached as an appendix.

  3. Full Scale Test of SSP 34m blade, edgewise loading LTT. Data Report 1

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Magda; Jensen, Find M.; Nielsen, Per H. (and others)

    2010-01-15

    This report is a part of a research project where a 34m wind turbine blade from SSP-Technology A/S has been tested in edgewise direction (LTT). The applied load is 60% of an unrealistic extreme event, corresponding to 75% of a certificated extreme load. This report describes the background, the test set up, the tests and the results. For this project, a new solution has been used for the load application and the solution for the load application is described in this report as well. The blade has been submitted to thorough examination. More areas have been examined with DIC, both global and local deflections have been measured, and also 378 strain gauge measurements have been performed. Furthermore Acoustic Emission has been used in order to detect damage while testing new load areas. The global deflection is compared with results from a previous test and results from FEM analyses in order to validate the solution as to how the gravity load on the blade was handled. Furthermore, the DIC measurement and the displacement sensors measurements are compared in order to validate the results from the DIC measurements. The report includes the results from the test and a description of the measurement equipment and the data acquisition. (author)

  4. 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

  5. Reduction of aerodynamic load fluctuation on wind turbine blades through active flow control

    Science.gov (United States)

    Velarde, John-Michael; Coleman, Thomas; Magstadt, Andrew; Aggarwal, Somil; Glauser, Mark

    2015-11-01

    The current set of experiments deals with implementing active flow control on a Bergey Excel 1, 1kW turbine. The previous work in our group demonstrated successfully that implementation of a simple closed-loop controller could reduce unsteady aerodynamic load fluctuation by 18% on a vertically mounted wing. Here we describe a similar flow control method adapted to work in the rotating frame of a 2.5m diameter wind turbine. Strain gages at the base of each blade measure the unsteady fluctuation in the blades and pressure taps distributed along the span of the blades feed information to the closed-loop control scheme. A realistic, unsteady flow field has been generated by placing a cylinder upstream of the turbine to induce shedding vortices at frequencies in the bandwidth of the first structural bending mode of the turbine blades. The goal of these experiments is to demonstrate closed-loop flow control as a means to reduce the unsteady fluctuation in the blades and increase the overall lifespan of the wind turbine.

  6. Application of Load Carrying Sandwich Elements in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Jensen, Jacob Fisker; Schultz, Jacob Pagh; Berggreen, Carl Christian

    2005-01-01

    The present work investigates the possibilities and drawbacks when applying sandwich as opposed to single skin composites in the flanges of the load carrying spar in a future 180 m wind turbine rotor. FEA is applied to investigate two basic designs with single skin and sandwich flanges respectively...

  7. Experimental evidence of inter-blade cavitation vortex development in Francis turbines at deep part load condition

    Science.gov (United States)

    Yamamoto, K.; Müller, A.; Favrel, A.; Avellan, F.

    2017-10-01

    Francis turbines are subject to various types of cavitation flow depending on the operating condition. To enable a smooth integration of the renewable energy sources, hydraulic machines are now increasingly required to extend their operating range, especially down to extremely low discharge conditions called deep part load operation. The inter-blade cavitation vortex is a typical cavitation phenomenon observed at deep part load operation. However, its dynamic characteristics are insufficiently understood today. In an objective of revealing its characteristics, the present study introduces a novel visualization technique with instrumented guide vanes embedding the visualization devices, providing unprecedented views on the inter-blade cavitation vortex. The binary image processing technique enables the successful evaluation of the inter-blade cavitation vortex in the images. As a result, it is shown that the probability of the inter-blade cavitation development is significantly high close to the runner hub. Furthermore, the mean vortex line is calculated and the vortex region is estimated in the three-dimensional domain for the comparison with numerical simulation results. In addition, the on-board pressure measurements on a runner blade is conducted, and the influence of the inter-blade vortex on the pressure field is investigated. The analysis suggests that the presence of the inter-blade vortex can magnify the amplitude of pressure fluctuations especially on the blade suction side. Furthermore, the wall pressure difference between pressure and suction sides of the blade features partially low or negative values near the hub at the discharge region where the inter-blade vortex develops. This negative pressure difference on the blade wall suggests the development of a backflow region caused by the flow separation near the hub, which is closely related to the development of the inter-blade vortex. The development of the backflow region is confirmed by the numerical

  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. Rotor hub vibration and blade loads reduction, and energy harvesting via embedded radial oscillator

    Science.gov (United States)

    Austruy, Julien

    An embedded radial absorber is investigated to control helicopter rotor hub vibration and blade loads. The absorber is modeled as a discrete mass moving in the spanwise direction within the blade. The absorber is retained in place and tuned with a spring and a damper. The radial absorber couples with lead-lag dynamic through Coriolis forces. The embedded radial absorber coupled to the helicopter is analyzed with a comprehensive rotorcraft model. The blade is modeled as an elastic beam undergoing flap bending, lag bending and elastic torsion, and a radial degree of freedom is added for the absorber. The tuning of the embedded radial absorber to a frequency close to 3/rev with no damping is shown to reduce significantly (up to 86%) the 4/rev in-plane hub forces of a 4-bladed hingeless rotor similar to a MBB BO-105 in high speed flight. The simulation shows that the absorber modifies the in-plane blade root shears to synchronize them to cancel each other in the transmission from rotating frame to fixed frame. A design of an embedded radial absorber experiment for hub vibration control is presented and it is concluded that for such high tuning frequencies as 3/rev, it is feasible to use a regular coil spring to compensate for the steady centrifugal force. Large reduction of blade lag shear (85%) and lag bending moment (71%) is achieved by tuning the embedded radial absorber close to 1/rev (also shown for a BO-105 like helicopter in high speed flight). The absorber reduces the amplitude of the lag bending moment at 1/rev, thus reducing the blade lead-lag motion and reducing the blade drag shear and lag bending moment. Finally, the use of the embedded radial absorber is investigated as a source electrical power when combined with an electromagnetic circuit. A model of the electromagnetic system is developed and validated, and an evaluation of the amount of power harvestable for different configurations is presented. The maximum power harvested was calculated to be 133

  10. Loads and performance data from a wind-tunnel test of model articulated helicopter rotors with 2 different blade torsional stiffnesses

    Science.gov (United States)

    Yeager, W. T., Jr.; Mantay, W. R.

    1983-01-01

    A passive means of tailoring helicopter rotor blades to improve performance and reduce loads was evaluated. The parameters investigated were blade torsional stiffness, blade section camber, and distance between blade structural elastic axis and blade tip aerodynamic center. This offset was accomplished by sweeping the tip. The investigation was conducted at advance ratios of 0.20, 0.30, and 0.40. Data are presented without analysis; however, cross referencing of performance data and harmonic loads data may be useful to the analyst for validating aeroelastic theories and design methodologies as well as for evaluating passive aeroelastic tailoring or rotor blade parameters.

  11. Simulation of Mechanical Behavior and Damage of a Large Composite Wind Turbine Blade under Critical Loads

    Science.gov (United States)

    Tarfaoui, M.; Nachtane, M.; Khadimallah, H.; Saifaoui, D.

    2018-04-01

    Issues such as energy generation/transmission and greenhouse gas emissions are the two energy problems we face today. In this context, renewable energy sources are a necessary part of the solution essentially winds power, which is one of the most profitable sources of competition with new fossil energy facilities. This paper present the simulation of mechanical behavior and damage of a 48 m composite wind turbine blade under critical wind loads. The finite element analysis was performed by using ABAQUS code to predict the most critical damage behavior and to apprehend and obtain knowledge of the complex structural behavior of wind turbine blades. The approach developed based on the nonlinear FE analysis using mean values for the material properties and the failure criteria of Tsai-Hill to predict failure modes in large structures and to identify the sensitive zones.

  12. Full scale test SSP 34m blade, edgewise loading LTT. Extreme load and PoC{sub I}nvE Data report

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Magda; Roczek-Sieradzan, A.; Jensen, Find M. (and others)

    2010-09-15

    This report is the second report covering the research and demonstration project 'Experimental blade research: Structural mechanisms in current and future large blades under combined loading', supported by the EUDP program. A 34m wind turbine blade from SSP-Technology A/S has been tested in edgewise direction (LTT). The blade has been submitted to thorough examination by means of strain gauges, displacement transducers and a 3D optical measuring system. This data report presents results obtained during full scale testing of the blade up to 80% Risoe load, where 80% Risoe load corresponds to 100% certification load. These pulls at 80% Risoe load were repeated and the results from these pulls were compared. The blade was reinforced according to a Risoe DTU invention, where the trailing edge panels are coupled. The coupling is implemented to prevent the out of plane deformations and to reduce peeling stresses in the adhesive joints. Test results from measurements with the reinforcement have been compared to results without the coupling. The report presents only the relevant results for the 80% Risoe load and the results applicable for the investigation of the influence of the invention on the profile deformation. (Author)

  13. Wind-Tunnel Evaluation of the Effect of Blade Nonstructural Mass Distribution on Helicopter Fixed-System Loads

    Science.gov (United States)

    Wilbur, Matthew L.; Yeager, Jr, William T.; Singleton, Jeffrey D.; Mirick, Paul H.; Wilkie, W K.

    1998-01-01

    This report provides data obtained during a wind-tunnel test conducted to investigate parametrically the effect of blade nonstructural mass on helicopter fixed-system vibratory loads. The data were obtained with aeroelastically scaled model rotor blades that allowed for the addition of concentrated nonstructural masses at multiple locations along the blade radius. Testing was conducted for advance ratios ranging from 0.10 to 0.35 for 10 blade-mass configurations. Three thrust levels were obtained at representative full-scale shaft angles for each blade-mass configuration. This report provides the fixed-system forces and moments measured during testing. The comprehensive database obtained is well-suited for use in correlation and development of advanced rotorcraft analyses.

  14. Immediately loaded blade implants. a histological and histomorphometrical evaluation after a long loading period. a retrospective 20 years analysis (1989-2009

    Directory of Open Access Journals (Sweden)

    Giovanna Iezzi

    2012-10-01

    Full Text Available Aim: Although the presence of mineralized tissues at the interface with blade implants has been reported, the view that blade implants cannot integrate still persists. Blades are the immediately loaded implants with the longest clinical history, so their histological evaluation may give results applicable to root-form implants. The aim of the present retrospective study was a histological evaluation of the peri-implant tissues in immediately loaded human blade implants retrieved after a long loading history. Materials and methods: Thirty-one implants were included in the present report, after a loading history varying from 2 to 23 years, with a mean of 15 years. The implants were processed for histological examination. Results: Histologically, the bone was in close and tight contact with the implants surface and no gaps or connective fibrous tissues were present at the implant-bone interface. The peri-implant bone was compact, mature, with the presence of small marrow spaces and Haversian canals. Many osteons were in contact with the implan surface. Most Haversian systems ran perpendicular to the major axis of the blades. In some fields it was possible to observe the presence of a few osteoblasts. Remodelling areas were present. Mean bone to implant contact percentage was, for all 31 implants, 43±5.2%. Conclusion: The present report showed that immediately loaded blade implants can achieve and maintain osseointegration under long-term function (more than 20 years.

  15. WISPER and WISPERX: Final definition of two standardised fatigue loading sequences for wind turbine blades

    Science.gov (United States)

    Tenhave, A. A.

    1992-09-01

    Relevant information used to develop WISPER (Wind turbine reference Spectrum) and WISPERX, standardized variable amplitude test loading histories for use in the fatigue design of horizontal axis wind turbine blades, is presented. WISPER and WISPERX are based on flap load service measurements on nine different horizontal axis wind turbines, covering a wide range of materials, rotor diameters and geographical locations. Their backgrounds are reported, basic data and associated data handling procedures are described, and quantitative data analysis results and statistical information on both standards are presented. The information given will enable fatigue specialists to judge whether the standard will suit their test objectives and to check for correct application of the load sequences on their test equipment.

  16. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    DEFF Research Database (Denmark)

    Pedersen, Mads M.; Larsen, Torben J.; Madsen, Helge Aa

    2017-01-01

    with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting. Conventional power curves are based on at least 180 h of 10 min mean values, but using the blade-mounted flow sensor both the observation average time and the overall...... assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations with higher accuracy, as the sensor follows the rotation of the rotor and because of the high correlation between the flow at the blades and the power production...

  17. Development of a Preliminary Design Method for Subsonic Splittered Blades in Highly Loaded Axial-Flow Compressors

    Directory of Open Access Journals (Sweden)

    Baojie Liu

    2017-03-01

    Full Text Available This paper presents a model for predicting the reference minimum-loss incidence and deviation angles of a blade arrangement with splitter vanes, which is probably a solution for future ultra-highly loaded axial compressor designs. The motivation of the modeling is to guide the blading design in splittered compressor design processes where the additional splitter vanes must be specially considered. The development of the model is based on a blade performance database from systematic numerical simulations. Basic correlations of the model are firstly proposed, which consider dominant blade geometry parameters related to blade loading, including camber angle and solidity. Secondly, geometric and aerodynamic corrections about orientation parameter, blade maximum thickness, inlet Mach number, and three-dimensional (3D effects are empirically incorporated into the basic correlations. Eventually, a subsonic 3D splittered rotor is designed using the correlations coupled with the corrections obtained from the validation of the model. The results indicate that the model is able to achieve a good agreement within an error band of ±1.0° for the predictions of both reference minimum-loss incidence and deviation angles, and the rotor designed using the model accomplishes the desired work input and flow deflection.

  18. Non-intrusive aerodynamic loads analysis of an aircraft propeller blade

    Energy Technology Data Exchange (ETDEWEB)

    Ragni, D.; Oudheusden, B.W. van; Scarano, F. [Delft University of Technology, Faculty of Aerospace Engineering, Delft (Netherlands)

    2011-08-15

    The flow field in a cross-sectional plane of a scaled Beaver DHC aircraft propeller has been measured by means of a stereoscopic PIV setup. Phase-locked measurements are obtained in a rotational frequency range from 18,900 to 21,000 rpm, at a relative Mach number of 0.6 at 3/4 propeller radius. The use of an adapted formulation of the momentum equation in differential form for rotating frame of references, integrated with isentropic relations as boundary conditions, allowed to compute the pressure field around the blade and the surface pressure distribution directly from the velocity data in the compressible regime. The procedure, extended to the computation of the aerodynamic lift and drag coefficients by a momentum contour integral approach, proved to be able to couple the aerodynamical loads to the flow field on the moving propeller blade, comparing favorably with a numerical simulation of the entire scaled model. Results are presented for two propeller rotation speeds and three different yawing angles. (orig.)

  19. Non-intrusive aerodynamic loads analysis of an aircraft propeller blade

    Science.gov (United States)

    Ragni, D.; van Oudheusden, B. W.; Scarano, F.

    2011-08-01

    The flow field in a cross-sectional plane of a scaled Beaver DHC aircraft propeller has been measured by means of a stereoscopic PIV setup. Phase-locked measurements are obtained in a rotational frequency range from 18,900 to 21,000 rpm, at a relative Mach number of 0.6 at ¾ propeller radius. The use of an adapted formulation of the momentum equation in differential form for rotating frame of references, integrated with isentropic relations as boundary conditions, allowed to compute the pressure field around the blade and the surface pressure distribution directly from the velocity data in the compressible regime. The procedure, extended to the computation of the aerodynamic lift and drag coefficients by a momentum contour integral approach, proved to be able to couple the aerodynamical loads to the flow field on the moving propeller blade, comparing favorably with a numerical simulation of the entire scaled model. Results are presented for two propeller rotation speeds and three different yawing angles.

  20. Experimental and numerical investigations of aerodynamic loads and 3D flow over non-rotating MEXICO blades

    NARCIS (Netherlands)

    Zhang, Y.; Gillebaart, T.; van Zuijlen, A.H.; van Bussel, G.J.W.; Bijl, H.

    2017-01-01

    This paper presents the experimental and numerical study on MEXICO wind turbine blades. Previous work by other researchers shows that large deviations exist in the loads comparison between numerical predictions and experimental data for the rotating MEXICO wind turbine. To reduce complexities and

  1. Analysis of 7- X 10-foot high speed wind tunnel shaft loads in support of fan blade failure investigation

    Science.gov (United States)

    Faison, Richard W.

    1987-01-01

    This is a report of the investigation of the High-Speed 7- X 10-Foot Wind Tunnel at NASA Langley Research Center, which experienced a catastrophic failure of all 18 Sitka spruce fan blades during operation at 0.8 Mach number on 2 July 1985. The High-Speed Tunnel, a closed-circuit/single-return atmospheric wind tunnel, had been operated since 1945 to support a wide range of subsonic aerodynamic tests and studies. The failed blade set had been in use since 1975. In addition to blade loss, the most significant damage was a bent main drive shaft for a total estimated damage loss of 1.7 million dollars. An analysis of the natural frequency characteristics as well as loads, reactions, stresses, and deflections of the fan drive system resulting from steady-state and dynamic loads due to unbalance was performed. Transient load cases were simulated by step input and ramp input loading functions intended to simulate the loss of one to nine blades (maximum unbalance forces).

  2. Prediction of Transient Engine Loads due to Hollow Fan Blade-off

    OpenAIRE

    Cosme, Nicolas; Chevrolet, David; Bonini, Jérome; Peseux, Bernard; Cartraud, Patrice

    2002-01-01

    International audience; The loss of a fan blade causes serious damages on an engine and can endanger the aircraft integrity and the safety of passengers. Commercial aircraft engines must then meet the FAA (Federal Aviation Administration) and JAA (Joint Aviation Authorities) certification requirements concerning the fan blade containment. The certification is validated through a Fan Blade-Off (FBO) test on a whole engine. The success in this test requires destructive and expensive development...

  3. A Critical Evaluation of Structural Analysis Tools used for the Design of Large Composite Wind Turbine Rotor Blades under Ultimate and Cycle Loading

    DEFF Research Database (Denmark)

    Lekou, D.J.; Bacharoudis, K. C.; Farinas, A. B.

    2015-01-01

    are evaluated. This paper shows the major findings of the comparative work performed by six organizations (universities and research institutes) participating in the benchmark exercise. The case concerns a 90m Glass/Epoxy blade of a horizontal axis 10MW wind turbine. The detailed blade geometry, the material...... properties of the constitutive layers and the aero-elastic loads formed the base by which global and local blade stiffness and strength are evaluated and compared. Static, modal, buckling and fatigue analysis of the blade were performed by each partner using their own tools; fully in-house developed...... is compared in terms of displacements, stresses, strains and failure indices at the ply level of the blade structure, eigen-frequencies and eigen-modes, critical buckling loads and Palmgren-Miner damage indices due to cycle loading. Results indicate that differences between estimations range from 0.5% to even...

  4. Performance and Vibratory Loads Data From a Wind-Tunnel Test of a Model Helicopter Main-Rotor Blade With a Paddle-Type Tip

    Science.gov (United States)

    Yeager, William T., Jr.; Noonan, Kevin W.; Singleton, Jeffrey D.; Wilbur, Matthew L.; Mirick, Paul H.

    1997-01-01

    An investigation was conducted in the Langley Transonic Dynamics Tunnel to obtain data to permit evaluation of paddle-type tip technology for possible use in future U.S. advanced rotor designs. Data was obtained for both a baseline main-rotor blade and a main-rotor blade with a paddle-type tip. The baseline and paddle-type tip blades were compared with regard to rotor performance, oscillatory pitch-link loads, and 4-per-rev vertical fixed-system loads. Data was obtained in hover and forward flight over a nominal range of advance ratios from 0.15 to 0.425. Results indicate that the paddle-type tip offers no performance improvements in either hover or forward flight. Pitch-link oscillatory loads for the paddle-type tip are higher than for the baseline blade, whereas 4-per-rev vertical fixed-system loads are generally lower.

  5. Direct Embedding of Fiber-Optical Load Sensors into Wind Turbine Blades

    DEFF Research Database (Denmark)

    Glavind, Lars; Buggy, Stephen; Olesen, Ib S.

    Long Period Gratings were embedded into the adhesive utilized in the matrix of a wind turbine blade. The LPGs were subsequently subjected to temperature-testing in order to assess their performance, which illustrates good embedding capabilities....

  6. Long-period gratings for selective monitoring of loads on a wind turbine blade.

    Science.gov (United States)

    Glavind, L; Buggy, S; Canning, J; Gao, S; Cook, K; Luo, Y; Peng, G D; Skipper, B F; Kristensen, M

    2014-06-20

    An optical fiber sensor based on long-period gratings (LPG) for selective measurements of flap- and edge-wise bending of a wind turbine blade is presented. Two consecutive LPGs separated by 40 mm interfere to improve resolution and reduce noise in a D-shaped fiber. The mode profile of the device was characterized experimentally to provide a model describing the mode couplings. The sensor was tested on a wind turbine blade.

  7. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    Directory of Open Access Journals (Sweden)

    M. M. Pedersen

    2017-11-01

    Full Text Available In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can be performed from a few hours or days of measurements.In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting.Conventional power curves are based on at least 180 h of 10 min mean values, but using the blade-mounted flow sensor both the observation average time and the overall assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations with higher accuracy, as the sensor follows the rotation of the rotor and because of the high correlation between the flow at the blades and the power production. This is the research question addressed in this paper.The method is first tested using aeroelastic simulations where the dependence of the radial position and effect of multiple blade-mounted flow sensors are also investigated. Next the method is evaluated on the basis of full-scale measurements on a pitch-regulated, variable-speed 3.6 MW wind turbine.It is concluded that the wind speed derived from the blade-mounted flow sensor is highly correlated with the

  8. Influence of modern studded and bladed soccer boots and sidestep cutting on knee loading during match play conditions.

    Science.gov (United States)

    Kaila, Rajiv

    2007-09-01

    The influence of modern studded and bladed soccer boots and sidestep cutting on noncontact knee loading during match play conditions is not fully understood. Modern soccer boot type and sidestep cutting compared with straight-ahead running do not significantly influence knee internal tibia axial and valgus moments, anterior joint forces, and flexion angles. Controlled laboratory study. Fifteen professional male outfield soccer players undertook trials of straight-ahead running and sidestep cutting at 30 degrees and 60 degrees with a controlled approach velocity on a Fédération Internationale de Football Association (FIFA) approved soccer surface. Two bladed and 2 studded soccer boots from 2 manufacturers were investigated. Three-dimensional inverse dynamics analysis determined externally applied internal/external tibia axial and valgus/varus moments, anterior forces, and flexion angles throughout stance. The soccer boot type imparted no significant difference on knee loading for each maneuver. Internal tibia and valgus moments were significantly greater for sidestep cutting at 30 degrees and 60 degrees compared with straight-ahead running. Sidestep cutting at 60 degrees compared with straight-ahead running significantly increased anterior joint forces. Varying soccer boot type had no effect on knee loading for each maneuver, but sidestep cutting significantly increased internal tibia and valgus moments and anterior joint forces. Sidestep cutting, irrespective of the modern soccer boot type worn, may be implicated in the high incidence of noncontact soccer anterior cruciate ligament injuries by significantly altering knee loading.

  9. Evaluation of Hydraulic Loads on the Runner Blades of a Kaplan Turbine using CFD Simulation and Model Test

    Directory of Open Access Journals (Sweden)

    Zoltan-Iosif Korka

    2016-10-01

    Full Text Available CFD (Computational Fluid Dynamic is today a standard procedure for analyzing and simulating the flow through several hydraulic machines. In this process, the fluid flow domain is divided into small volumes where the governing equations are converted into algebraic ones, which are numerically solved. Computational results strongly depend on the applied mathematical model and on the numerical methods used for converting the governing equations into the algebraic ones. The goal of the paper is to evaluate, by numerical simulation, the hydraulic loads (forces and torques on the runner blades of an existent Kaplan turbine and to compare them with the experimental results obtained from model test.

  10. FE Modeling of Blade Couple with Friction Contacts Under Dynamic Loading

    Czech Academy of Sciences Publication Activity Database

    Pešek, Luděk; Půst, Ladislav; Vaněk, František; Veselý, Jan

    2014-01-01

    Roč. 2, č. 3 (2014), s. 229-238 ISSN 2321-3558 R&D Projects: GA ČR GA101/09/1166 Institutional support: RVO:61388998 Keywords : turbine blades * dry friction * damping Subject RIV: BI - Acoustics http://www.tvi-in.com/Journals/journaldetail.aspx?Id=201406251115146464844edeb39be66

  11. Wind-tunnel investigation of the effects of blade tip geometry on the interaction of torsional loads and performance for an articulated helicopter rotor

    Science.gov (United States)

    Yeager, W. T.; Mantay, W. R.

    1981-01-01

    The Langley transonic dynamics tunnel was used to determine the degree of correlation between rotor performance and the dynamic twist generated by changes in blade tip geometry using an articulated rotor with four different tip geometries at advance ratios of 0.20, 0.30 and 0.35. Based on the data obtained, it is concluded that: (1) there appears to be no strong correlation between blade torsion loads and rotor performance prediction; (2) for a given rotor task at each advance ratio investigated, both the azimuthal variation of torsional moment and the mean torsional moment at 81% radius are configuration dependent; (3) reducing the nose down twist on the advancing blade appears to be more important to forward flight performance than increasing the nose down twist on the retreating blade; (4) the rotor inflow model used was important in predicting the performance of the adaptive rotor; and (5) neither rigid blade solidity effects, inflow environment, nor blade torsion loads can be used alone to accurately predict active rotor performance.

  12. New Method for Dual-Axis Fatigue Testing of Large Wind Turbine Blades Using Resonance Excitation and Spectral Loading

    Energy Technology Data Exchange (ETDEWEB)

    White, D.

    2004-04-01

    The blades of a wind turbine are generally considered to be the most critical component of the wind turbine system. The fundamental purpose of performing fatigue tests on wind turbine blades is to demonstrate that a blade, when manufactured to a certain set of specifications, has the prescribed reliability and service life. The purpose of the research conducted for this project is the advancement of knowledge and capabilities in the area of wind turbine blade fatigue testing.

  13. Pultrusion of a vertical axis wind turbine blade part-II: combining the manufacturing process simulation with a subsequent loading scenario

    NARCIS (Netherlands)

    Baran, Ismet; Hattel, Jesper H.; Tutum, Cem C.; Akkerman, Remko

    2015-01-01

    This paper in particular deals with the integrated modeling of a pultruded NACA0018 blade profile being a part of EU funded DeepWind project. The manufacturing aspects of the pultrusion process are associated with the preliminary subsequent service loading scenario. A 3D thermo-chemical analysis of

  14. A Two-Bladed Teetering Hub configuration for the DTU 10 MW RWT: loads considerations

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Aagaard Madsen, Helge; Rasmussen, Flemming

    2014-01-01

    frequency and the rotational forcing, the tower mode frequency is lowered with a modified tower stiffness distributions. The loads caused by the aerodynamic unbalance are instead addressed by introducing a teetering hub configuration. The load alleviation potential of the teetering hub, and the required...

  15. The Effects of Hull Pitching Motions and Waves on Periodic Propeller Blade Loads.

    Science.gov (United States)

    1982-09-01

    1 INTRODUCTION.....................................1 EXPERIMENTAL TECHNIQUES.................................4 DYNAMOMETRY ...loads. 3 II. EXPERIMENTAL TECHNIQUES A. Dynamometry All experiments were conducted using the hull and propeller shown in Figure 1 on Carriage II at

  16. Fan blade protection system

    Science.gov (United States)

    Hermans, Thomas C. (Inventor); Wakeman, Thomas G. (Inventor); Hauser, Ambrose A. (Inventor)

    1993-01-01

    In one type of aircraft propulsion system, propeller blades are mounted on a ring which surrounds a turbine. An annular space exists between the turbine and the ring. If a propeller blade should break free, the unbalanced centrifugal load tends to deform the ring. The invention reduces the deformation, as by locating spacers between the turbine and the ring.

  17. Inflow characteristics associated with high-blade-loading events in a wind farm

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, N.D.

    1993-07-01

    The stochastic characteristics of the turbulent inflow have been shown to be of major significance in the accumulation of fatigue in wind turbines. Because most of the wind turbine installations in the US have taken place in multi-turbine or wind farm configurations, the fatigue damage associated with the higher turbulence levels within such arrangements must be taken into account when making estimates of component service lifetimes. The simultaneous monitoring of two adjacent wind turbines over a wide range of turbulent inflow conditions has given the authors more confidence in describing the structural load distributions that can be expected in such an environment. The adjacent testing of the two turbines allowed the authors to postulate that observed similarities in the response dynamics and load distributions could be considered quasi-universal, while the dissimilarities could be considered to result from the differing design of the rotors. The format has also allowed them to begin to define appropriate statistical load distribution models for many of the critical components in which fatigue is a major driver of the design. In addition to the adjacent turbine measurements, they also briefly discuss load distributions measured on a teetered-hub turbine.

  18. Fatigue behaviour of fiberglass wind turbine blade material under variable amplitude loading

    Energy Technology Data Exchange (ETDEWEB)

    Delft, D.R.V. Van; Winkel, G.D. de [Delft Univ. of Technology, STEVIN Lab., Delft (Netherlands); Joosse, P.A. [Stork Product Engineering b.v., Amsterdam (Netherlands)

    1996-09-01

    In the work presented here fatigue tests with the WISPER and WISPERX load sequence have been carried out and analysed. The test programme includes tests at low stress levels which results in fatigue lives of 50 millions of cycles. The results are compared with constant amplitude tests in the very high cycle range, carried out in a previous programme. The results are also compared with ECN results in the lower cycle range (on identical specimens). It appeared, that the difference between the fatigue life of the specimens tested with the WISPER and the WISPERX load sequence is larger than can be expected from the theoretical damage rates. Moreover, the slope of the S-N data differs from theoretical values obtained by using commonly applied design rules. (au)

  19. Performance of Savonius Blade Waterwheel with Variation of Blade Number

    Science.gov (United States)

    Sule, L.; Rompas, P. T. D.

    2018-02-01

    The utilization of water energy source is mainly used as a provider of electrical energy through hydroelectric power. The potential utilization of water flow energy is relatively small. The objective of this study is to know the best blade of Savonius waterwheel with various variables such as water discharge, blade number, and loading. The data used the efficiency of waterwheel, variation of blade number, variable water discharge, and loading in the shaft. The test results have shown that the performances of a top-water mill with the semicircular curve where the variation in the number of blades are 4, 6, and 8 at discharge and loading of 0.01587 m3/s and 1000 grams respectively were 9.945%, 13.929%, and 17.056% respectively. The blades number of 8 obtained the greatest performance. The more number of blades the greater the efficiency of the waterwheel Savonius.

  20. Pultrusion of a vertical axis wind turbine blade part-II: combining the manufacturing process simulation with a subsequent loading scenario

    DEFF Research Database (Denmark)

    Baran, Ismet; Hattel, Jesper Henri; Tutum, Cem Celal

    2015-01-01

    This paper in particular deals with the integrated modeling of a pultruded NACA0018 blade profile being a part of EU funded DeepWind project. The manufacturing aspects of the pultrusion process are associated with the preliminary subsequent service loading scenario. A 3D thermochemical analysis...... of the pultrusion process is sequentially coupled with a 2D quasi-static mechanical analysis in which the process induced residual stresses and distortions are predicted using the generalized plane stain elements in a commercial finite element software ABAQUS. The temperature- and cure-dependent resin modulus...... is implemented by employing the cure hardening instantaneous linear elastic (CHILE) model in the process simulation. The subsequent bent-in place simulation of the pultruded blade profile is performed taking the residual stresses into account. The integrated numerical simulation tool predicts the internal stress...

  1. Reduction of fatigue loads on jacket substructure through blade design optimization for multimegawatt wind turbines at 50 m water depths

    DEFF Research Database (Denmark)

    NJOMO WANDJI, Wilfried; Pavese, Christian; Natarajan, Anand

    2016-01-01

    This paper addresses the reduction of the fore-aft damage equivalent moment at the tower base for multi-megawatt offshore wind turbines mounted on jacket type substructures at 50 m water depths. The study investigates blade design optimization of a reference 10 MW wind turbine under standard wind...... on the efficient design of other components such as the constituents of the nacelle....

  2. Transonic turbine blade loading calculations using different turbulence models - effects of reflecting and non-reflecting boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Djouimaa, S. [Physical Department, Sciences Faculty, Batna University, Ave Chahid Boukhlouf Med, El-Hadi, 05000 Batna (Algeria); Messaoudi, L. [Mechanical Department, Engineering Sciences Faculty, Batna University, Ave Chahid Boukhlouf Med, El-Hadi, 05000 Batna (Algeria); Giel, Paul W. [QSS Group, Inc., NASAGlenn Research Center Cleveland, OH 44135 (United States)

    2007-03-15

    The objective of this study is to simulate the transonic gas turbine blade-to-blade compressible fluid flow. We are interested mainly in the determination of the pressure distribution around the blade. The particular blade architecture makes these simulations more complex due to the variety of phenomena induced by this flow. Our study is based on the experiment performed by Giel and colleagues. Tests were conducted in a linear cascade at the NASA Glenn Research Center. The test article was a turbine rotor with design flow turning of 136{sup o} and an axial chord of 12.7cm. Simulations were performed on an irregular quadratic structured grid with the FLUENT software package which solves the Navier-Stokes equations by using finite volume methods. Two-dimensional stationary numerical simulations were made under turbulent conditions allowing us to compare the characteristic flow effects of Reflecting Boundary Conditions (RBC) and Non-Reflecting Boundary Conditions (NRBC) newly implemented in FLUENT 6.0. Many simulations were made to compare different turbulence models: a one equation model (Spalart-Allmaras), several two-equation models (k-{epsilon}, RNG k-{epsilon}, Realizable k-{epsilon}, SST k-{omega}), and a Reynolds-stress model (RSM). Also examined were the effects of the inlet turbulence intensities (0.25% and 7%), the exit Mach numbers (1.0 and 1.3) and the inlet Reynolds numbers (0.5x10{sup 6} and 1x10{sup 6}). The results obtained show a good correlation with the experiment. (author)

  3. Comparison of calculated and measured blade loads on a full-scale tilting proprotor in a wind tunnel

    Science.gov (United States)

    Johnson, W.

    1980-01-01

    The loads measured in a wind tunnel on a full-scale tilting proprotor are compared with calculated results. The data consists primarily of oscillatory beamwise bending moments at 35% radial station, oscillatory spindle chord bending moments, and oscillatory pitch link loads. The measured and calculated results as a function of thrust are compared over a range of nacelle angles from 0 to 75 deg, and a range of speeds from 80 to 185 knots.

  4. Design of a wind tunnel scale model of an adaptive wind turbine blade for active aerodynamic load control experiments

    NARCIS (Netherlands)

    Hulskamp, A.W.; Beukers, A.; Bersee, H.E.N.; Van Wingerden, J.W.; Barlas, T.

    2007-01-01

    Within wind energy research there is a drive towards the development of a “smart rotor”; a rotor of which the loading can be measured and controlled through the application of a sensor system, a control system and an aerodynamic device. Most promising solutions from an aerodynamic point of view are

  5. Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Xavier Ortiz

    2015-03-01

    Full Text Available To improve knowledge of the wind loads on photovoltaic structures mounted on flat roofs at the high angles required in high latitudes, and to study starting flow on low aspect ratio wind turbine blades, a series of wind tunnel tests were undertaken. Thin flat plates of aspect ratios between 0.4 and 9.0 were mounted on a sensitive three-component instantaneous force and moment sensor. The Reynolds numbers varied from 6 × 104 to 2 × 105. Measurements were made for angles of attack between 0° and 90° both in the free stream and in wall proximity with increased turbulence and mean shear. The ratio of drag to lift closely follows the inverse tangent of the angle of incidence for virtually all measurements. This implies that the forces of interest are due largely to the instantaneous pressure distribution around the plate and are not significantly influenced by shear stresses. The instantaneous forces appear most complex for the smaller aspect ratios but the intensity of the normal force fluctuations is between 10% and 20% in the free-steam but can exceed 30% near the wall. As the wind tunnel floor is approached, the lift and drag reduce with increasing aspect ratio, and there is a reduction in the high frequency components of the forces. It is shown that the centre of pressure is closer to the centre of the plates than the quarter-chord position for nearly all cases.

  6. 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....

  7. Bladed disc crack diagnostics using blade passage signals

    Science.gov (United States)

    Hanachi, Houman; Liu, Jie; Banerjee, Avisekh; Koul, Ashok; Liang, Ming; Alavi, Elham

    2012-12-01

    One of the major potential faults in a turbo fan engine is the crack initiation and propagation in bladed discs under cyclic loads that could result in the breakdown of the engines if not detected at an early stage. Reliable fault detection techniques are therefore in demand to reduce maintenance cost and prevent catastrophic failures. Although a number of approaches have been reported in the literature, it remains very challenging to develop a reliable technique to accurately estimate the health condition of a rotating bladed disc. Correspondingly, this paper presents a novel technique for bladed disc crack detection through two sequential signal processing stages: (1) signal preprocessing that aims to eliminate the noises in the blade passage signals; (2) signal postprocessing that intends to identify the crack location. In the first stage, physics-based modeling and interpretation are established to help characterize the noises. The crack initiation can be determined based on the calculated health monitoring index derived from the sinusoidal effects. In the second stage, the crack is located through advanced detrended fluctuation analysis of the preprocessed data. The proposed technique is validated using a set of spin rig test data (i.e. tip clearance and time of arrival) that was acquired during a test conducted on a bladed military engine fan disc. The test results have demonstrated that the developed technique is an effective approach for identifying and locating the incipient crack that occurs at the root of a bladed disc.

  8. Vortex-induced vibrations on a modern wind turbine blade

    DEFF Research Database (Denmark)

    Heinz, Joachim Christian; Sørensen, Niels N.; Zahle, Frederik

    2016-01-01

    -body-based structural model of HAWC2 and the incompressible computational fluid dynamics solver EllipSys3D. The study utilizes detached eddy simulation computations and considers the three-dimensional blade geometry including blade twist and taper. A preliminary frequency analysis of the load variations on a stiff...... blade showed that an inclined inflow with a velocity component along the blade axis can trigger a spanwise correlated vortex shedding over large parts of the blade. Moderate wind speeds were sufficient to generate vortex shedding with frequencies close to the first edgewise eigenfrequency of the blade...

  9. Measurements of blade aerodynamics on a rotor in the field

    Energy Technology Data Exchange (ETDEWEB)

    Graham, J.M.R. [Imperical College, Dept. of Aeronautics, London (United Kingdom)

    1997-12-31

    This contribution describes the field test measurements undertaken on an instrumented rotor at the Rutherford Appleton Laboratory, Oxfordshire, UK, during the period 1994 - 97. The programme was directed at improving the prediction of the steady and unsteady rotor blade loading, particularly the loads arising from the stalling of the blade. The measured data consisted of blade surface pressure distributions sampled at 50Hz at 6 sections along the span of one blade of the 17m diameter, 3 bladed, fixed pitch, upwind H.A.W.T., together with measurements of the incident velocity. (au)

  10. 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....

  11. Load Measurements

    DEFF Research Database (Denmark)

    Kock, Carsten Weber; Vesth, Allan

    The report describes Load measurements carried out on a given wind turbine. The aim of the measurement program regarding the loads on the turbine is to verify the basic characteristics of the wind turbine and loads on the blades, the rotor and the tower, using [Ref 1], [Ref2] and [Ref 3]. Regarding...... the fatigue loads, the rotor, blades and tower moments are presented. The fatigue loads are evaluated using rainflow counting described in detail in Ref. [1]. The 1Hz equivalent load ranges are calculated at different wind speeds. All information regarding the instrumentation is collected in [ref 4] and [ref...

  12. Aerodynamics and Optimal Design of Biplane Wind Turbine Blades

    Science.gov (United States)

    Chiu, Phillip

    In order to improve energy capture and reduce the cost of wind energy, in the past few decades wind turbines have grown significantly larger. As their blades get longer, the design of the inboard region (near the blade root) becomes a trade-off between competing structural and aerodynamic requirements. State-of-the-art blades require thick airfoils near the root to efficiently support large loads inboard, but those thick airfoils have inherently poor aerodynamic performance. New designs are required to circumvent this design compromise. One such design is the "biplane blade", in which the thick airfoils in the inboard region are replaced with thinner airfoils in a biplane configuration. This design was shown previously to have significantly increased structural performance over conventional blades. In addition, the biplane airfoils can provide increased lift and aerodynamic efficiency compared to thick monoplane inboard airfoils, indicating a potential for increased power extraction. This work investigates the fundamental aerodynamic aspects, aerodynamic design and performance, and optimal structural design of the biplane blade. First, the two-dimensional aerodynamics of biplanes with relatively thick airfoils are investigated, showing unique phenomena which arise as a result of airfoil thickness. Next, the aerodynamic design of the full biplane blade is considered. Two biplane blades are designed for optimal aerodynamic loading, and their aerodynamic performance quantified. Considering blades with practical chord distributions and including the drag of the mid-blade joint, it is shown that biplane blades have comparable power output to conventional monoplane designs. The results of this analysis also show that the biplane blades can be designed with significantly less chord than conventional designs, a characteristic which enables larger blade designs. The aerodynamic loads on the biplane blades are shown to be increased in gust conditions and decreased under

  13. 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.

  14. 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

    of helicopter and wind turbine blade research have shown the potential of shape morphing in reducing blade loads. Morphing technologies, along with other control concepts, are investigated under Task 2.3 of WP “Lightweight Rotor”, against aerodynamic compliance and requirements of the complete wind turbine.......e. no loss of local/global stiffness or strength and/or fatigue life. The purpose is to report efforts towards the use of new morphing blade section designs and the structural solutions for smart blades (developed in Task 2.3). The objective is to define, assess and demonstrate innovative concepts...... 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...

  15. Flowfield Characteristics on a Retreating Rotor Blade

    Science.gov (United States)

    2015-12-03

    fixed wing, and then as a rotor blade in a low-speed wind tunnel . Fixed-wing results from load measurements and flow visualization showed that the sharp...wing airloads (Figure 1.3) and tuft visualization, to Particle Image Velocimetry (PIV) under a blade held fixed as part of a rotor in a wind tunnel [43...were performed in the 2.13m×2.74m John Harper wind tunnel at our institution. The untwisted rectangular blade has a NACA 0013 planform. The rotor used

  16. Wind turbine blade with viscoelastic damping

    Science.gov (United States)

    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).

  17. Vibration analysis of gas turbine blade using FEM

    International Nuclear Information System (INIS)

    Iqbal, M.J.; Chohan, G.Y.; Khusnood, S.; Khan, M.A.

    2003-01-01

    In a typical turbo-machine, there is a stator row of blades, which guide the gases onto a rotor row of blades, to extract the mechanical power from the machine. A typical rotor blade was sees upstream disturbance from the stator row and as it rotates, receive a corresponding number of increasing and decreasing lift and moment forces alternating periodically, depending on the number of stator blades/nozzles/guide vanes. Thus all the blades in a turbo-machine receiver their major periodic excitation at a frequency equal to nozzle passing frequency. Since these forces are periodic, one has to consider several number of these harmonics in determining whether resonance takes place, when one of these harmonics coincides with any of the natural frequencies of the blades. Turbine blades have a variety of natural modes of vibration, predominantly as blade alone but also in combination with flexing of the disc rim. These mode occur at characteristic frequencies, which are determined by the distribution of mass and stiffness (in bending or torsion), resulting from the variable thickness over the blade area. Since the advent of steam turbines and their application in various sectors of industry, it is a common experience that a blade failure is a major cause of breakdown in these machines. Blade failures due to fatigue are predominantly vibration related. The dynamic loads on the blading can arise from many sources, the predominant being the source of the operation principles on which the machine is designed. This work deals with vibration analysis of a gas turbine blade using a finite element package ANSYS. Determined the natural frequencies and mode shapes for a turbine blade and a rectangular blade. Results have been validated experimentally using a rectangular blade. ANSYS results have also been compared against published results. (author)

  18. Investigate plow blade optimization.

    Science.gov (United States)

    2015-08-01

    The main technique for removing accumulated snow from roadways is through the use of snow plows and snow plow : blades (blades), or cutting edges. The blade is bolted to the snow plow, and it is the component of the plowing system that : makes contac...

  19. 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...

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

    DEFF Research Database (Denmark)

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

    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......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...... 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....

  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. 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.

  3. Distribution of defects in wind turbine blades and reliability assessment of blades containing defects

    DEFF Research Database (Denmark)

    Stensgaard Toft, Henrik; 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......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...... 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...

  4. 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....

  5. Stress analysis and life prediction of gas turbine blade

    Science.gov (United States)

    Hsiung, H. C.; Dunn, A. J.; Woodling, D. R.; Loh, D. L.

    1988-01-01

    A stress analysis procedure is presented for a redesign of the Space Shuttle Main Engine high pressure fuel turbopump turbine blades. The analysis consists of the one-dimensional scoping analysis to support the design layout and the follow-on three-dimensional finite element analysis to confirm the blade design at operating loading conditions. Blade life is evaluated based on high-cycle fatigue and low-cycle fatigue.

  6. Development of 52 inches last stage blade for steam turbines

    International Nuclear Information System (INIS)

    Suzuki, Atsuhide; Hisa, Shoichi; Nagao, Shinichiro; Ogata, Hisao

    1986-01-01

    The last stage blades of steam turbines are the important component controlling the power output and performance of plants. In order to realize a unit of large capacity and high efficiency, the proper exhaust area and the last stage blades having good performance are indispensable. Toshiba Corp. has completed the development of the 52 inch last stage blades for 1500 and 1800 rpm steam turbines. The 52 inch last stage blades are the longest in the world, which have the annular exhaust area nearly 1.5 times as much as that of 41 inch blades used for 1100 MW, 1500 rpm turbines in nuclear power stations. By adopting these 52 inch blades, the large capacity nuclear power plants up to 1800 MW can be economically constructed, the rate of heat consumption of 1350 MW plants is improved by 3 ∼ 4 % as compared with 41 inch blades, and in the plants up to 1100 MW, LP turbines can be reduced from three sets to two. The features of 52 inch blades, the flow pattern and blade form design, the structural strength analysis and the erosion withstanding property, and the verification by the rotation test of the actual blades, the performance test using a test turbine, the vibration analysis of the actually loaded blades and the analysis of wet steam behavior are reported. (Kako, I.)

  7. Accelerated fatigue testing of LM 19.1 blades

    DEFF Research Database (Denmark)

    Kristensen, Ole Jesper Dahl; Jørgensen, E.

    2003-01-01

    material. In addition to the thermal imaging surveillance the blades were instrumented with strain gauges. This report presents the temperature duringtest, calibration test results, moment range measurements, strain statistics, thermal imaging registrations and a determination of the size and cause......A series of 19.1 metre wind turbine blades manufactured by LM Glasfiber A/S of Lunderskov, Denmark were subjected to a series of flapwise fatigue tests. The object of these fatigue tests is to evaluate the impact of an increased load on the blade in afatigue test and to give information...... if it is possible to increase the load in fatigue test to shorten test time. The tests were carried out as a part of a project financed by the Danish Energy Agency. During the fatigue tests the blades have beensurveyed with thermal imaging equipment to determine how an increase in fatigue load affects the blade...

  8. Flutter of swept fan blades

    Science.gov (United States)

    Kielb, R. E.; Kaza, K. R. V.

    1985-01-01

    The effect of sweep on fan blade flutter is studied by applying the analytical methods developed for aeroelastic analysis of advance turboprops. Two methods are used. The first method utilizes an approximate structural model in which the blade is represented by a swept, nonuniform beam. The second method utilizes a finite element technique to conduct modal flutter analysis. For both methods the unsteady aerodynamic loads are calculated using two dimensional cascade theories which are modified to account for sweep. An advanced fan stage is analyzed with 0, 15 and 30 degrees of sweep. It is shown that sweep has a beneficial effect on predominantly torsional flutter and a detrimental effect on predominantly bending flutter. This detrimental effect is shown to be significantly destabilizing for 30 degrees of sweep.

  9. 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.

  10. Shoulder Blade Squeeze (Posture Exercise)

    Science.gov (United States)

    ... Exercise & Weight Exercise at Home Shoulder Blade Squeeze Shoulder Blade Squeeze Make an Appointment Ask a Question Find ... do it: Stand straight and tall. Pull your shoulder blades back and slightly downward to bring your elbows ...

  11. Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades

    Directory of Open Access Journals (Sweden)

    Li Yang

    2007-01-01

    Full Text Available 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 pressure ratio, stable operating range, and aerodynamic noise. Detailed flow measurement was performed in outlet flow field for investigating the responsible flow mechanisms. The optimized blade can cause a spanwise redistribution of flow toward the blade midspan and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at midspan. In addition, the measured spectrums show that the broadband noise of the impeller is dominant.

  12. Instrumented composite turbine blade for health monitoring

    Science.gov (United States)

    Robison, Kevin E.; Watkins, Steve E.; Nicholas, James; Chandrashekhara, K.; Rovey, Joshua L.

    2012-04-01

    A health monitoring approach is investigated for hydrokinetic turbine blade applications. In-service monitoring is critical due to the difficult environment for blade inspection and the cost of inspection downtime. Composite blade designs have advantages that include long life in marine environments and great control over mechanical properties. Experimental strain characteristics are determined for static loads and free-vibration loads. These experiments are designed to simulate the dynamic characteristics of hydrokinetic turbine blades. Carbon/epoxy symmetric composite laminates are manufactured using an autoclave process. Four-layer composite beams, eight-layer composite beams, and two-dimensional eight-layer composite blades are instrumented for strain. Experimental results for strain measurements from electrical resistance gages are validated with theoretical characteristics obtained from in-house finite-element analysis for all sample cases. These preliminary tests on the composite samples show good correlation between experimental and finite-element strain results. A health monitoring system is proposed in which damage to a composite structure, e.g. delamination and fiber breakage, causes changes in the strain signature behavior. The system is based on embedded strain sensors and embedded motes in which strain information is demodulated for wireless transmission.

  13. Acoustic design of rotor blades using a genetic algorithm

    Science.gov (United States)

    Wells, V. L.; Han, A. Y.; Crossley, W. A.

    1995-01-01

    A genetic algorithm coupled with a simplified acoustic analysis was used to generate low-noise rotor blade designs. The model includes thickness, steady loading and blade-vortex interaction noise estimates. The paper presents solutions for several variations in the fitness function, including thickness noise only, loading noise only, and combinations of the noise types. Preliminary results indicate that the analysis provides reasonable assessments of the noise produced, and that genetic algorithm successfully searches for 'good' designs. The results show that, for a given required thrust coefficient, proper blade design can noticeably reduce the noise produced at some expense to the power requirements.

  14. Structural experiment of wind turbine blades; Fushayo blade no zairyo rikigakuteki jikken kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Seki, K.; Shimizu, Y.; Kuroyanagi, H. [Tokai University, Tokyo (Japan)

    1997-11-25

    Aluminum, GFRP and composite of aluminum coated with carbon as structural materials for wind turbine blades were bending-tested, to improve blade bending stiffness, understand stress conditions at each position, and clarify structural dynamic strength by the bending-failure test. It is possible to estimate stress conditions at each position from the test results of displacement and strain at each load. The test results with GFRP are well explained qualitatively by the boundary theory, known as a theory for composite materials. The test gives reasonable material strength data, useful for designing wind turbines of high functions and safety. The results of the blade bending-failure test are in good agreement with the calculated structural blade strength. It is also found that GFRP is a good material of high structural strength for wind turbines. 8 refs., 6 tabs.

  15. 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.

  16. A shape adaptive airfoil for a wind turbine blade

    Science.gov (United States)

    Daynes, Stephen; Weaver, Paul M.

    2011-04-01

    The loads on wind turbine components are primarily from the blades. It is important to control these blade loads in order to avoid damaging the wind turbine. Rotor control technology is currently limited to controlling the rotor speed and the pitch of the blades. As blades increase in length it becomes less desirable to pitch the entire blade as a single rigid body, but instead there is a requirement to control loads more precisely along the length of the blade. This can be achieved with aerodynamic control devices such as flaps. Morphing technologies are good candidates for wind turbine flaps because they have the potential to create structures that have the conflicting abilities of being load carrying, light-weight and shape adaptive. A morphing flap design with a highly anisotropic cellular structure is presented which is able to undergo large deflections and high strains without a large actuation penalty. An aeroelastic analysis couples the work done by aerodynamic loads on the flap, the flap strain energy and the required actuation work to change shape. The morphing flap is experimentally validated with a manufactured demonstrator and shown to have reduced actuation requirements compared to a conventional hinged flap.

  17. Structural Optimization Design of Large Wind Turbine Blade considering Aeroelastic Effect

    Directory of Open Access Journals (Sweden)

    Yuqiao Zheng

    2017-01-01

    Full Text Available This paper presents a structural optimization design of the realistic large scale wind turbine blade. The mathematical simulations have been compared with experimental data found in the literature. All complicated loads were applied on the blade when it was working, which impacts directly on mixed vibration of the wind rotor, tower, and other components, and this vibration can dramatically affect the service life and performance of wind turbine. The optimized mathematical model of the blade was established in the interaction between aerodynamic and structural conditions. The modal results show that the first six modes are flapwise dominant. Meanwhile, the mechanism relationship was investigated between the blade tip deformation and the load distribution. Finally, resonance cannot occur in the optimized blade, as compared to the natural frequency of the blade. It verified that the optimized model is more appropriate to describe the structure. Additionally, it provided a reference for the structural design of a large wind turbine blade.

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

    OpenAIRE

    E. Korkmaz; M. Gölcü; C. Kurbanoğlu

    2017-01-01

    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 ex...

  19. 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).

  20. Wind-tunnel evaluation of an advanced main-rotor blade design for a utility-class helicopter

    Science.gov (United States)

    Yeager, William T., Jr.; Mantay, Wayne R.; Wilbur, Matthew L.; Cramer, Robert G., Jr.; Singleton, Jeffrey D.

    1987-01-01

    An investigation was conducted in the Langley Transonic Dynamics Tunnel to evaluate differences between an existing utility-class main-rotor blade and an advanced-design main-rotor blade. The two rotor blade designs were compared with regard to rotor performance oscillatory pitch-link loads, and 4-per-rev vertical fixed-system loads. Tests were conducted in hover and over a range of simulated full-scale gross weights and density altitude conditions at advance ratios from 0.15 to 0.40. Results indicate that the advanced blade design offers performance improvements over the baseline blade in both hover and forward flight. Pitch-link oscillatory loads for the baseline rotor were more sensitive to the test conditions than those of the advanced rotor. The 4-per-rev vertical fixed-system load produced by the advanced blade was larger than that produced by the baseline blade at all test conditions.

  1. Improving Bending Moment Measurements on Wind Turbine Blades

    Energy Technology Data Exchange (ETDEWEB)

    Post, Nathan L.

    2016-03-15

    Full-scale fatigue testing of wind turbine blades is conducted using resonance test techniques where the blade plus additional masses is excited at its first resonance frequency to achieve the target loading amplitude. Because there is not a direct relationship between the force applied by an actuator and the bending moment, the blade is instrumented with strain gauges that are calibrated under static loading conditions to determine the sensitivity or relationship between strain and applied moment. Then, during dynamic loading the applied moment is calculated using the strain response of the structure. A similar procedure is also used in the field to measure in-service loads on turbine blades. Because wind turbine blades are complex twisted structures and the deflections are large, there is often significant cross-talk coupling in the sensitivity of strain gauges placed on the structure. Recent work has shown that a sensitivity matrix with nonzero cross terms must be employed to find constant results when a blade is subjected to both flap and lead-lag loading. However, even under controlled laboratory conditions, potential for errors of 3 percent or more in the measured moment exist when using the typical cross-talk matrix approach due to neglecting the influence of large deformations and torsion. This is particularly critical when considering a biaxial load as would be applied on the turbine or during a biaxial fatigue test. This presentation describes these results demonstrating errors made when performing current loads measurement practices on wind turbine blades in the lab and evaluating potential improvements using enhanced cross-talk matrix approaches and calibration procedures.

  2. 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.

  3. Analysis and Tests of Pultruded Blades for Wind Turbine Rotors

    Energy Technology Data Exchange (ETDEWEB)

    Cheney, M. C.(PS Enterprises, Glastonbury, Connecticut); Olsen, T.; Quandt, G.; Archidiacono, P.

    1999-07-19

    PS Enterprises, Inc. investigated a flexible, downwind, free-yaw, five-blade rotor system employing pultruded blades. A rotor was designed, manufactured and tested in the field. A preliminary design study and proof of concept test were conducted to assess the feasibility of using pultruded blades for wind turbine rotors. A 400 kW turbine was selected for the design study and a scaled 80 kW rotor was fabricated and field tested as a demonstration of the concept. The design studies continued to support the premise that pultruded blades offer the potential for significant reductions in rotor weight and cost. The field test provided experimental performance and loads data that compared well with predictions using the FLEXDYNE aeroelastic analysis. The field test also demonstrated stable yaw behavior and the absence of stall flutter over the wind conditions tested. During the final year of the contract, several studies were conducted by a number of independent consultants to address specific technical issues related to pultruded blades that could impact the commercial viability of turbines using this technology. The issues included performance, tower strikes, yaw stability, stall flutter, fatigue, and costs. While the performance of straight pultruded blades was projected to suffer a penalty of about 13% over fully twisted and tapered blades, the study showed that an aerodynamic fairing over the inner 40% could recover 85% of that loss while still keeping the blade cost well below that of conventional blades. Other results of the study showed that with proper design, rotors using pultruded blades could operate without aeroelastic problems, have acceptable fatigue life, and cost less than half that of rotors employing conventionally manufactured blades.

  4. Full-Scale Fatigue Testing of a Wind Turbine Blade in Flapwise Direction and Examining the Effect of Crack Propagation on the Blade Performance

    Directory of Open Access Journals (Sweden)

    Othman Al-Khudairi

    2017-10-01

    Full Text Available In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i as received blade (ii when a crack of 200 mm was introduced between the web and the spar cap and (iii when the crack was extended to 1000 mm. Calibration pull-tests for all three states of the blade were performed to obtain the strain-bending moment relationship of the blade according to the estimated target bending moment (BM which the blade is expected to experience in its service life. The resultant data was used to apply appropriate load in the fatigue tests. The blade natural frequencies in flapwise and edgewise directions over a range of frequency domain were found by modal testing for all three states of the blade. The blade first natural frequency for each state was used for the flapwise fatigue tests. These were performed in accordance with technical specification IEC TS 61400-23. The fatigue results showed that, for a 200 mm crack between the web and spar cap at 9 m from the blade root, the crack did not propagate at 50% of the target BM up to 62,110 cycles. However, when the load was increased to 70% of target BM, some damages were detected on the pressure side of the blade. When the 200 mm crack was extended to 1000 mm, the crack began to propagate when the applied load exceeded 100% of target BM and the blade experienced delaminations, adhesive joint failure, compression failure and sandwich core failure.

  5. Full-Scale Fatigue Testing of a Wind Turbine Blade in Flapwise Direction and Examining the Effect of Crack Propagation on the Blade Performance.

    Science.gov (United States)

    Al-Khudairi, Othman; Hadavinia, Homayoun; Little, Christian; Gillmore, Gavin; Greaves, Peter; Dyer, Kirsten

    2017-10-03

    In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i) as received blade (ii) when a crack of 200 mm was introduced between the web and the spar cap and (iii) when the crack was extended to 1000 mm. Calibration pull-tests for all three states of the blade were performed to obtain the strain-bending moment relationship of the blade according to the estimated target bending moment (BM) which the blade is expected to experience in its service life. The resultant data was used to apply appropriate load in the fatigue tests. The blade natural frequencies in flapwise and edgewise directions over a range of frequency domain were found by modal testing for all three states of the blade. The blade first natural frequency for each state was used for the flapwise fatigue tests. These were performed in accordance with technical specification IEC TS 61400-23. The fatigue results showed that, for a 200 mm crack between the web and spar cap at 9 m from the blade root, the crack did not propagate at 50% of the target BM up to 62,110 cycles. However, when the load was increased to 70% of target BM, some damages were detected on the pressure side of the blade. When the 200 mm crack was extended to 1000 mm, the crack began to propagate when the applied load exceeded 100% of target BM and the blade experienced delaminations, adhesive joint failure, compression failure and sandwich core failure.

  6. Blade design and operating experience on the MOD-OA 200 kW wind turbine at Clayton, New Mexico

    Science.gov (United States)

    Linscott, B. S.; Shaltens, R. K.

    1979-01-01

    Two 60 foot long aluminum wind turbine blades were operated for over 3000 hours on the MOD-OA wind turbine. The first signs of blade structural damage were observed after 400 hours of operation. Details of the blade design, loads, cost, structural damage, and repair are discussed.

  7. Large-Scale Advanced Prop-Fan (LAP) blade design

    Science.gov (United States)

    Violette, John A.; Sullivan, William E.; Turnberg, Jay E.

    1984-01-01

    This report covers the design analysis of a very thin, highly swept, propeller blade to be used in the Large-Scale Advanced Prop-Fan (LAP) test program. The report includes: design requirements and goals, a description of the blade configuration which meets requirements, a description of the analytical methods utilized/developed to demonstrate compliance with the requirements, and the results of these analyses. The methods described include: finite element modeling, predicted aerodynamic loads and their application to the blade, steady state and vibratory response analyses, blade resonant frequencies and mode shapes, bird impact analysis, and predictions of stalled and unstalled flutter phenomena. Summarized results include deflections, retention loads, stress/strength comparisons, foreign object damage resistance, resonant frequencies and critical speed margins, resonant vibratory mode shapes, calculated boundaries of stalled and unstalled flutter, and aerodynamic and acoustic performance calculations.

  8. Dynamic Stability of Rotating Blades with Transverse Cracks

    Directory of Open Access Journals (Sweden)

    T.Y. Ng

    2003-01-01

    Full Text Available In this paper, the main objective is to examine the effects of transverse cracks on the dynamic instability regions of an axially loaded rotating blade. The blade is modeled as an Euler-Bernoulli beam. To reduce the governing equations to a set of ordinary differential equations in matrix form, Hamilton's principle is used in conjunction with the assumed-mode method. The crack is accounted for by considering the energy release rate and the parametric instability regions are obtained using Bolotin's first approximation. Benchmark results are presented for cracked rotating blades at different rotating speeds, crack lengths and crack positions.

  9. Materials for Wind Turbine Blades: An Overview.

    Science.gov (United States)

    Mishnaevsky, Leon; Branner, Kim; Petersen, Helga Nørgaard; Beauson, Justine; McGugan, Malcolm; Sørensen, Bent F

    2017-11-09

    A short overview of composite materials for wind turbine applications is presented here. Requirements toward the wind turbine materials, loads, as well as available materials are reviewed. Apart from the traditional composites for wind turbine blades (glass fibers/epoxy matrix composites), natural composites, hybrid and nanoengineered composites are discussed. Manufacturing technologies for wind turbine composites, as well their testing and modelling approaches are reviewed.

  10. Materials for Wind Turbine Blades: An Overview

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon; Branner, Kim; Petersen, Helga Nørgaard

    2017-01-01

    A short overview of composite materials for wind turbine applications is presented here. Requirements toward the wind turbine materials, loads, as well as available materials are reviewed. Apart from the traditional composites for wind turbine blades (glass fibers/epoxy matrix composites), natural...... composites, hybrid and nanoengineered composites are discussed. Manufacturing technologies for wind turbine composites, as well their testing and modelling approaches are reviewed....

  11. Failure Analysis of Fencing Blades

    Science.gov (United States)

    Kibaroglu, D.; Baydogan, M.; Cimenoglu, H.; Bas, B.; Yagsi, C.; Aliyeva, N.

    2017-05-01

    This study deals with the failure analysis of broken fencing blades (one épée and one foil). For the characterization of the broken blades, metallographic examinations, chemical analysis, hardness measurements, fracture surface examinations and tensile tests were performed. Maximum stress occurred at the outer fibres of the blades was estimated as high as 1456 MPa and 1298 MPa for épée and foil, respectively. Results showed that failure of the blades was initiated from a notch, which has been formed as the result of an impact action during training, or from the groove machined along the blade for inserting an electrical wire. In order to increase resistance of the blades against such failures, alternative blade material, modified blade geometry and a surface hardening treatment were proposed.

  12. Deflection estimation of a wind turbine blade using FBG sensors embedded in the blade bonding line

    International Nuclear Information System (INIS)

    Kim, Sang-Woo; Kang, Woo-Ram; Jeong, Min-Soo; Lee, In; Kwon, Il-Bum

    2013-01-01

    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. (paper)

  13. A blade deflection monitoring system

    DEFF Research Database (Denmark)

    2017-01-01

    A wind turbine blade comprising a system for monitoring the deflection of a wind turbine blade is described. The system comprises a wireless range-measurement system, having at least one wireless communication device located towards the root end of the blade and at least one wireless communication...

  14. Influence of Splitter Blades on the Cavitation Performance of a Double Suction Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Wei Yang

    2014-04-01

    Full Text Available In order to study the influence of splitter blades on double suction centrifugal pumps two impellers with and without splitter blades were investigated numerically and experimentally. Three-dimensional turbulence simulations with and without full cavitation model were applied to simulate the flow in the two pumps with different impellers. The simulation results agreed with the experiment results and the internal flows were analyzed. Both the numerical and experimental results show that by adding splitter blades the hydraulic performance and the cavitation performance of the pump are improved. The pump efficiency is increased especially at high flow rate condition. The pump high efficiency area is extended dramatically. At the same time since the splitter blades share some part of the blade loading, the pump critical NPSH value is decreased. Obvious pressure increase and velocity decrease at blade suction surface near leading edge were observed in the pump impeller with splitter blades. And the pump cavitation performance was improved consequently.

  15. Gas Turbine Blade Damper Optimization Methodology

    Directory of Open Access Journals (Sweden)

    R. K. Giridhar

    2012-01-01

    Full Text Available The friction damping concept is widely used to reduce resonance stresses in gas turbines. A friction damper has been designed for high pressure turbine stage of a turbojet engine. The objective of this work is to find out effectiveness of the damper while minimizing resonant stresses for sixth and ninth engine order excitation of first flexure mode. This paper presents a methodology that combines three essential phases of friction damping optimization in turbo-machinery. The first phase is to develop an analytical model of blade damper system. The second phase is experimentation and model tuning necessary for response studies while the third phase is evaluating damper performance. The reduced model of blade is developed corresponding to the mode under investigation incorporating the friction damper then the simulations were carried out to arrive at an optimum design point of the damper. Bench tests were carried out in two phases. Phase-1 deals with characterization of the blade dynamically and the phase-2 deals with finding optimal normal load at which the blade resonating response is minimal for a given excitation. The test results are discussed, and are corroborated with simulated results, are in good agreement.

  16. Rotating turbine blade pyrometer

    Science.gov (United States)

    Buchele, D. R.; Lesco, D. J.

    1974-01-01

    Non-contacting pyrometer system optically measures surface temperature distribution on rotating turbine blade, comprising line-by-line scan via fiber optic probe. Each scan line output is converted to digital signals, temporarily stored in buffer memory, and then processed in minicomputer for display as temperature.

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

    DEFF Research Database (Denmark)

    Castaignet, Damien Bruno

    -weighted model predictive control, tuned in order to target only the flapwise blade root loads at the frequencies contributing the most to blade root fatigue damage (the 1P, 2P and 3P frequencies), and to avoid unnecessary wear and tear of the actuators at high frequencies. A disturbance model consisting...... in periodic disturbances at the rotor speed harmonic frequencies and a quasi-steady input disturbance is aggregated to an analytical model of a spinning blade with trailing edge flaps. Simulations on a multi-megawatt wind turbine show the potential of the trailing edge flaps to reduce the flapwise blade root......, 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...

  19. BWR control blade replacement strategies

    International Nuclear Information System (INIS)

    Kennard, M.W.; Harbottle, J.E.

    2000-01-01

    The reactivity control elements in a BWR, the control blades, perform three significant functions: provide shutdown margin during normal and accident operating conditions; provide overall core reactivity control; and provide axial power shaping control. As such, the blades are exposed to the core's neutron flux, resulting in irradiation of blade structural and absorber materials. Since the absorber depletes with time (if B 4 C is used, it also swells) and the structural components undergo various degradation mechanisms (e.g., embrittlement, corrosion), the blades have limits on their operational lifetimes. Consequently, BWR utilities have implemented strategies that aim to maximize blade lifetimes while balancing operational costs, such as extending a refuelling outage to shuffle high exposure blades. This paper examines the blade replacement strategies used by BWR utilities operating in US, Europe and Asia by assembling information related to: the utility's specific blade replacement strategy; the impact the newer blade designs and changes in core operating mode were having on those strategies; the mechanical and nuclear limits that determined those strategies; the methods employed to ensure that lifetime limits were not exceeded during operation; and blade designs used (current and replacement blades). (author)

  20. Modelling of lightning streamer formation and propagation in wind turbine blades

    DEFF Research Database (Denmark)

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

    2013-01-01

    The positioning of lightning air terminations along a wind turbine blade is a complex issue to consider when designing the lightning protection of wind turbine blades. According to the IEC 61400-24 on lightning protection of wind turbines, the interception efficiency depends on the effectiveness ...... models can involve a high level of detail and therefore be used in the detailed positioning of air terminations in blades equipped with conductive elements such as carbon fiber or electrical monitoring systems (load, temperature, etc.)....

  1. Active Robust Control of Elastic Blade Element Containing Magnetorheological Fluid

    Science.gov (United States)

    Sivrioglu, Selim; Cakmak Bolat, Fevzi

    2018-03-01

    This research study proposes a new active control structure to suppress vibrations of a small-scale wind turbine blade filled with magnetorheological (MR) fluid and actuated by an electromagnet. The aluminum blade structure is manufactured using the airfoil with SH3055 code number which is designed for use on small wind turbines. An interaction model between MR fluid and the electromagnetic actuator is derived. A norm based multi-objective H2/H∞ controller is designed using the model of the elastic blade element. The H2/H∞ controller is experimentally realized under the impact and steady state aerodynamic load conditions. The results of experiments show that the MR fluid is effective for suppressing vibrations of the blade structure.

  2. 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...

  3. Structural Evaluation of Exo-Skeletal Engine Fan Blades

    Science.gov (United States)

    Kuguoglu, Latife; Abumeri, Galib; Chamis, Christos C.

    2003-01-01

    The available computational simulation capability is used to demonstrate the structural viability of composite fan blades of innovative Exo-Skeletal Engine (ESE) developed at NASA Glenn Research Center for a subsonic mission. Full structural analysis and progressive damage evaluation of ESE composite fan blade is conducted through the NASA in-house computational simulation software system EST/BEST. The results of structural assessment indicate that longitudinal stresses acting on the blade are in compression. At a design speed of 2000 rpm, pressure and suction surface outer most ply stresses in longitudinal, transverse and shear direction are much lower than the corresponding composite ply strengths. Damage is initiated at 4870 rpm and blade fracture takes place at rotor speed of 7735 rpm. Damage volume is 51 percent. The progressive damage, buckling, stress and strength results indicate that the design at hand is very sound because of the factor of safety, damage tolerance, and buckling load of 6811 rpm.

  4. 3D numerical analysis and optimization of aerodynamic performance of turbine blade

    International Nuclear Information System (INIS)

    Wang Dingbiao; Xie Wen; Zhou Junjie

    2010-01-01

    To reduce the stator profile loss and improve the efficiency of the industrial steam turbine, a numerical analysis and optimization of the data for the steam turbine stator blade are conducted by the NUMECA,a CFD software. The result shows that, compared with the original blade, the 'after loading' blade is with the best static pressure coefficient distribution, and effectively postpones the transition point position, reduces the radial pressure gradient of suction surface, and cut down the secondary flow loss effectively. The total pressure losses of the 'after loading' blade is 1.03%, which is the least, and the single-stage efficiency is 94.462%, which is the maximum and increases 14.33%. Thus, the aerodynamic performance of stage is improved obviously, the profile loss decreases through using the 'after loading' blade. (authors)

  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. Subsonic Swept Fan Blade

    Science.gov (United States)

    Gallagher, Edward J. (Inventor); Rogers, Thomas H. (Inventor)

    2017-01-01

    A gas turbine engine includes a spool, a turbine coupled to drive the spool, a propulsor coupled to be driven at a at a design speed by the turbine through the spool, and a gear assembly coupled between the propulsor and the spool. Rotation of the turbine drives the propulsor at a different speed than the spool. The propulsor includes a hub and a row of propulsor blades that extend from the hub. Each of the propulsor blades includes an airfoil body. The leading edge of the airfoil body has a swept profile such that, at the design speed, a component of a relative velocity vector of a working gas that is normal to the leading edge is subsonic along the entire radial span.

  7. Blade Vibration Measurement System

    Science.gov (United States)

    Platt, Michael J.

    2014-01-01

    The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.

  8. Turbine blade temperature calculation and life estimation - a sensitivity analysis

    Directory of Open Access Journals (Sweden)

    Majid Rezazadeh Reyhani

    2013-06-01

    Full Text Available The overall operating cost of the modern gas turbines is greatly influenced by the durability of hot section components operating at high temperatures. In turbine operating conditions, some defects may occur which can decrease hot section life. In the present paper, methods used for calculating blade temperature and life are demonstrated and validated. Using these methods, a set of sensitivity analyses on the parameters affecting temperature and life of a high pressure, high temperature turbine first stage blade is carried out. Investigated uncertainties are: (1 blade coating thickness, (2 coolant inlet pressure and temperature (as a result of secondary air system, and (3 gas turbine load variation. Results show that increasing thermal barrier coating thickness by 3 times, leads to rise in the blade life by 9 times. In addition, considering inlet cooling temperature and pressure, deviation in temperature has greater effect on blade life. One of the interesting points that can be realized from the results is that 300 hours operation at 70% load can be equal to one hour operation at base load.

  9. Tuned liquid column dampers for mitigation of edgewise vibrations in rotating wind turbine blades

    DEFF Research Database (Denmark)

    Zhang, Zili; Basu, Biswajit; Nielsen, Søren R.K.

    2015-01-01

    Edgewise vibrations in wind turbine blades are lightly damped, and large amplitude vibrations induced by the turbulence may significantly shorten the fatigue life of the blade. This paper investigates the performance of tuned liquid column dampers (TLCDs) for mitigating edgewise vibrations......, with the consideration of both the space limitation inside the blade and the constraint of the liquid motion. The edgewise modal load for the 2-DOF model has been calculated from a more sophisticated 13-DOF aeroelastic wind turbine model, which includes the coupling of the blade-tower-drivetrain vibration...

  10. Measurements of UWB Pulse Propagation Along a Wind Turbine Blade at 1 to 20 GHz

    DEFF Research Database (Denmark)

    Hejselbæk, Johannes; Syrytsin, Igor A.; Eggers, Patrick Claus F.

    2018-01-01

    This paper describes propagation measurements of an Ultra Wide Band (UWB) pulse along a full-scale wind turbine blade. The aim is to use the UWB channel characteristics to determine the deflection of the wind turbine blade under different wind loads. The frequency response is measured from 1 to 20...... the reflection originates a ray-tracing study incorporating a model of the curvature of the blade have been conducted. This showed the area causing the reflections depended highly on the placement of the antenna on the wind turbine blade....

  11. Full-Scale Wind Tunnel Test of an Individual Blade Control System for a UH-60 Helicopter

    National Research Council Canada - National Science Library

    Jacklin, Stephen A; Haber, Axel; de Simone, Gary; Norman, Thomas R; Kitaplioglu, Cahit; Shinoda, Patrick

    2002-01-01

    .... The acquired wind tunnel data set includes measurements of rotor performance, steady and dynamic hub forces and moments, rotor loads, control system loads, and blade vortex interaction (BVI) noise...

  12. Ultimate strength of a large wind turbine blade

    DEFF Research Database (Denmark)

    Jensen, Find Mølholt

    2009-01-01

    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. In the thesis 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...

  13. 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

    The structural reliability of wind turbine components can have a profound impact on both the profitability and reputation of a wind turbine manufacturer or supplier of wind turbine components. The issue of reliability is of critical concern when large wind farm co-operatives are considered......, and when wind turbines are located in remote regions where the cost of inspections and repairs can be very high. From a structural viewpoint, wind turbine blades are subjected to very complex loading histories with coupled deformation modes. The long-term reliability of wind turbine blades requires...... 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...

  14. A simulation study of active feedback supression of dynamic response in helicopter rotor blades

    Science.gov (United States)

    Kana, D. D.; Bessey, R. L.; Dodge, F. T.

    1975-01-01

    A parameter study is presented for active feedback control applied to a helicopter rotor blade during forward flight. The study was performed on an electromechanical apparatus which included a mechanical model rotor blade and electronic analog simulation of interaction between blade deflections and aerodynamic loading. Blade response parameters were obtained for simulated vortex impinging at the blade tip at one pulse per revolution, and for a pulse which traveled from the blade tip toward its root. Results show that the response in a 1 - 10-per-rev frequency band is diminished by the feedback action, but at the same time responses at frequencies above 10-per-rev become increasingly more prominent with increased feedback amplitude, and can even lead to instability at certain levels. It appears that the latter behavior results from limitations of the laboratory simulation apparatus, rather than genuine potential behavior for a prototype helicopter.

  15. 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 % .

  16. Stress analysis of composite wind turbine blade by finite element method

    Science.gov (United States)

    Yeh, Meng-Kao; Wang, Chen-Hsu

    2017-10-01

    In this study, the finite element analysis software ANSYS was used to analyze the composite wind turbine blade. The wind turbine blade model used is adopted from the 5 MW model of US National Renewable Energy Laboratory (NREL). The wind turbine blade is a sandwich structure, comprising outermost carbon fiber cloth/epoxy composites, the inner glass fiber/vinylester layers, and PVC foam core, together with stiffeners. The wind pressure is converted into the load on the blade structure. The stress distribution and deformation of wind turbine blade were obtained by considering different pitch angles and at different angular positions. The Tsai-Hill criterion was used to determine the failure of wind turbine blade. The results show that at the 0° pitch angle, the wind turbine blade is subjected to the largest combined load and therefore the stress is the largest; with the increasing pitch angle, the load gradually decreases and the stress is also smaller. The stress and displacement are the greatest when the wind blade is located at 120° angular position from its highest vertex.

  17. 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...

  18. Mitigating the Long term Operating Extreme Load through Active Control

    DEFF Research Database (Denmark)

    Koukoura, Christina; Natarajan, Anand

    2014-01-01

    on the blades. Through gain scheduling of the controller (modifications of the proportional Kp and the integral Ki gains) the extreme loads are mitigated, ensuring minimum instantaneous variations in the power production for operation above rated wind speed. The response of the blade load is examined......The parameters influencing the long term extreme operating design loads are identified through the implementation of a Design of Experiment (DOE) method. A function between the identified critical factors and the ultimate out-of-plane loads on the blade is determined. Variations in the initial...... blade azimuth location are shown to affect the extreme blade load magnitude during operation in normal turbulence wind input. The simultaneously controlled operation of generator torque variation and pitch variation at low blade pitch angles is detected to be responsible for very high loads acting...

  19. 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.

  20. Resonant vibration control of wind turbine blades

    DEFF Research Database (Denmark)

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

    2010-01-01

    formulation accounts for arbitrary mass density distributions, general elastic crosssection properties and geometric stiffness effects due to internal stresses. A compact, linear formulation for aerodynamic forces with associated stiffness and damping terms is established and added to the structural model....... 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....

  1. Influence of Icing on the Modal Behavior of Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Sudhakar Gantasala

    2016-10-01

    Full Text Available Wind turbines installed in cold climate sites accumulate ice on their structures. Icing of the rotor blades reduces turbine power output and increases loads, vibrations, noise, and safety risks due to the potential ice throw. Ice accumulation increases the mass distribution of the blade, while changes in the aerofoil shapes affect its aerodynamic behavior. Thus, the structural and aerodynamic changes due to icing affect the modal behavior of wind turbine blades. In this study, aeroelastic equations of the wind turbine blade vibrations are derived to analyze modal behavior of the Tjaereborg 2 MW wind turbine blade with ice. Structural vibrations of the blade are coupled with a Beddoes-Leishman unsteady attached flow aerodynamics model and the resulting aeroelastic equations are analyzed using the finite element method (FEM. A linearly increasing ice mass distribution is considered from the blade root to half-length and thereafter constant ice mass distribution to the blade tip, as defined by Germanischer Lloyd (GL for the certification of wind turbines. Both structural and aerodynamic properties of the iced blades are evaluated and used to determine their influence on aeroelastic natural frequencies and damping factors. Blade natural frequencies reduce with ice mass and the amount of reduction in frequencies depends on how the ice mass is distributed along the blade length; but the reduction in damping factors depends on the ice shape. The variations in the natural frequencies of the iced blades with wind velocities are negligible; however, the damping factors change with wind velocity and become negative at some wind velocities. This study shows that the aerodynamic changes in the iced blade can cause violent vibrations within the operating wind velocity range of this turbine.

  2. 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.

  3. 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); Ordonez-Sanchez, Stephanie [University of Strathclyde; Porter, Kate E. [University of Strathclyde; Johnstone, Cameron M. [University of Strathclyde; Doman, Darrel A. [Dalhousie University; Pegg, Michael J. [Dalhousie University

    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.

  4. Probabilistic Fatigue Design of Composite Material for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2011-01-01

    In the present paper a probabilistic design approach to fatigue design of wind turbine blades is presented. The physical uncertainty on the fatigue strength for composite material is estimated using public available fatigue tests. Further, the model uncertainty on Miner rule for damage accumulation...... is also estimated based on test results. The results show that Miners rule gives a non-conservative estimate on the accumulated damage at failure. The reliability of a wind turbine blade is estimated for both out-of-plane and in-plane loading using three different design standards. The estimated annual...

  5. Structural Design of a Horizontal-Axis Tidal Current Turbine Composite Blade

    Energy Technology Data Exchange (ETDEWEB)

    Bir, G. S.; Lawson, M. J.; Li, Y.

    2011-10-01

    This paper describes the structural design of a tidal composite blade. The structural design is preceded by two steps: hydrodynamic design and determination of extreme loads. The hydrodynamic design provides the chord and twist distributions along the blade length that result in optimal performance of the tidal turbine over its lifetime. The extreme loads, i.e. the extreme flap and edgewise loads that the blade would likely encounter over its lifetime, are associated with extreme tidal flow conditions and are obtained using a computational fluid dynamics (CFD) software. Given the blade external shape and the extreme loads, we use a laminate-theory-based structural design to determine the optimal layout of composite laminas such that the ultimate-strength and buckling-resistance criteria are satisfied at all points in the blade. The structural design approach allows for arbitrary specification of the chord, twist, and airfoil geometry along the blade and an arbitrary number of shear webs. In addition, certain fabrication criteria are imposed, for example, each composite laminate must be an integral multiple of its constituent ply thickness. In the present effort, the structural design uses only static extreme loads; dynamic-loads-based fatigue design will be addressed in the future. Following the blade design, we compute the distributed structural properties, i.e. flap stiffness, edgewise stiffness, torsion stiffness, mass, moments of inertia, elastic-axis offset, and center-of-mass offset along the blade. Such properties are required by hydro-elastic codes to model the tidal current turbine and to perform modal, stability, loads, and response analyses.

  6. New type of wind turbine with composite rotor blade

    Energy Technology Data Exchange (ETDEWEB)

    Rys, J. [Cracow Univ. of Technology, Krakow (Poland)

    1995-11-01

    During the last three years a new type of a wind turbine has been designed and tested in Division of Machine Design at Cracow University of Technology. The wind turbine consists of four main units: (1) rotor with two blades, each of them having an aerodynamically formed surface made of a laminated composite material bordered by a metallic frame; (2) directing system consisting of one rotor unit which drives blades about their own axis and controls the orientation of the turbine towards the wind; (3) supporting and transmissing system; and (4) foundation consisting of typical reinforced concrete plates fastened together, convenient to transport. The paper presents the method describing simulation of motion of the turbine. Such an approach gives one the possibility to analyze the maximum load acting in the vicinity of the blade and the load response of the elements of the turbine. A certain useful technique is demonstrated which can be applied to determine the load distribution. It is used to find e.g. the optimal fastening of internal metallic frame of the rotor blade. Specific and important advantages of the new type of engine are summarized in the final remarks as follows: perfect static and dynamic balancing, nice geometric shape of rotor which can be made of typical materials, low mass and cost per unit, typical technology of elements, easy mounting and dismounting. Several designing and technological solutions are illustrated in graphs and drawings.

  7. Useful life consumption analysis of the blades of a gas turbine by thermofluency during constant load operation; Analisis de consumo de vida util por termofluencia en alabes de turbinas de gas durante operacion con carga constante

    Energy Technology Data Exchange (ETDEWEB)

    Ortega Quiroz, Gerardo Daniel

    2005-08-15

    A new analytical model for creep life prediction of gas turbine blades is proposed. The ultimate tensile strength is included to reflect heat-to-heat variations in strength. A thermo mechanical analysis is made using the finite element method. With the stress distribution obtained, some creep life prediction models as the Norton-Bailey and Dorn-Bailey models were reviewed as well as the Larson-Miller parameter. The time to failure data obtained with the previous analysis, was used to determine the new creep life prediction model coefficients. The results obtained are in good concordance with experimental data for IN-738-LN gas turbine blades. [Spanish] En el presente trabajo se propone un nuevo modelo analitico para predecir la vida util por termofluencia en alabes de turbinas de gas, donde se incluye el esfuerzo ultimo de tension para reflejar el efecto que tiene la variacion de la temperatura en la rigidez del material. Para lograr esto, primero se hizo un analisis termomecanico del alabe, utilizando el metodo de elementos finitos. Con los esfuerzos obtenidos, se hizo una revision de los modelos de consumo de vida de Norton-Bailey y de Dorn-Bailey. Tambien se utilizo el parametro Larson-Miller para obtener datos de consumo de vida. Con los resultados de los analisis anteriores, fue posible determinar los coeficientes del modelo propuesto. Los resultados obtenidos estan en buena concordancia con los datos experimentales del alabe, y muestran un error menor que el de los modelos revisados.

  8. Failure analysis of turbine blades

    International Nuclear Information System (INIS)

    Iorio, A.F.; Crespi, J.C.

    1989-01-01

    Two 20 MW gas turbines suffered damage in blades belonging to the 2nd. stage of the turbine after 24,000 hours of duty. From research it arises that the fuel used is not quite adequate to guarantee the blade's operating life due to the excess of SO 3 , C and Na existing in combustion gases which cause pitting to the former. Later, the corrosion phenomenon is presented under tension produced by working stress enhanced by pitting where Pb is its main agent. A change of fuel is recommended thus considering the blades will reach the operational life they were designed for. (Author) [es

  9. Design Procedure of 4-Bladed Propeller

    African Journals Online (AJOL)

    PROF. O. E. OSUAGWU

    2013-09-01

    Sep 1, 2013 ... Diameter – The diameter of the imaginary cycle scribed by the blade ... Blade root – Fillet area. The region of transition from .... Propeller diameter. To estimate the weight of all blades and the polar moment of inertia of a blade, the approximate formula given by [8] was adopted. 3. 982.1. ,. YR. B. W. Weight.

  10. 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....... To select the actuator and design the flap actuation region, the flap hinge moment is estimated via a CFD analysis. To obtain the desired flap deflection of ±4°, three actuators are required. The design of the flap actuation region is validated using a test bed with a skin hinge. However, because the skin...

  11. Dual-axis resonance testing of wind turbine blades

    Science.gov (United States)

    Hughes, Scott; Musial, Walter; White, Darris

    2014-01-07

    An apparatus (100) for fatigue testing test articles (104) including wind turbine blades. The apparatus (100) includes a test stand (110) that rigidly supports an end (106) of the test article (104). An actuator assembly (120) is attached to the test article (104) and is adapted for substantially concurrently imparting first and second forcing functions in first and second directions on the test article (104), with the first and second directions being perpendicular to a longitudinal axis. A controller (130) transmits first and second sets of displacement signals (160, 164) to the actuator assembly (120) at two resonant frequencies of the test system (104). The displacement signals (160, 164) initiate the actuator assembly (120) to impart the forcing loads to concurrently oscillate the test article (104) in the first and second directions. With turbine blades, the blades (104) are resonant tested concurrently for fatigue in the flapwise and edgewise directions.

  12. Demonstration of partial pitch 2-bladed wind turbine

    DEFF Research Database (Denmark)

    Kim, Taeseong; Zahle, Frederik; Troldborg, Niels

    This is the final report for the EUDP project performed from January 2012 to December 2015. The main objective for the project was to demonstrate the potential of the partial pitch two-bladed (PP-2B) technology. DTU Wind Energy took a responsibility for three workpackages (WPs) among 6 WPs which...... were aerodynamic evaluation of partial pitch technology (WP2), aeroelastic analysis of two-bladed turbine (WP3) and On-site testing (WP4). For the WP2, a comprehensive set of 3D CFD simulations including the gap between inner and outer part of the blade and vortex generators (VGs) of both cross...... pitch concept and detailed load analyses were performed. Also the comparison studies between numerical results and experimental results were performed. Moreover stability analyses for the PP- 2B turbine have been performed with HAWC2 and modal analysis using Hill’s method was performed to calculate...

  13. Fan blade crack diagnosis method study

    OpenAIRE

    Sheng Fu; Yinbo Gao

    2016-01-01

    This article presents a discrete mathematical model for fan blades and theoretically analyses the mathematical relationship between the location and depth of crack and fan blade natural frequency. On the basis of the blade mathematical model, using the theoretical computed natural frequency as the fault feature, this article proposes a fast and efficient fan blade crack fault diagnosis method. Transfer matrix method is used to calculate the first three-order blade natural frequencies under di...

  14. Design of Linear Control System for Wind Turbine Blade Fatigue Testing

    DEFF Research Database (Denmark)

    Toft, Anders; Roe-Poulsen, Bjarke Nørskov; Christiansen, Rasmus

    2016-01-01

    This paper proposes a linear method for wind turbine blade fatigue testing at Siemens Wind Power. The setup consists of a blade, an actuator (motor and load mass) that acts on the blade with a sinusoidal moment, and a distribution of strain gauges to measure the blade flexure. Based...... on the desired output, namely the amplitude of the blade. Furthermore, the model has been linearised to make it suitable for linear analysis and control design methods.\\\\ The controller is designed based on a simplified and linearised model, and its gain parameter determined using pole placement. The model...... variants have been simulated in the MATLAB toolbox Simulink, which shows that the controller design based on the simple model performs adequately with the non-linear model. Moreover, the developed controller solves the robustness issue found in the existent solution and also reduces the needed energy...

  15. Structural degradation of a large composite wind turbine blade in a full-scale fatigue test

    DEFF Research Database (Denmark)

    Chen, Xiao

    -23 (ed. 2014). A conventional single-axis mass resonance excitation (rotating mass) method is used as it is now still widely used for blade certification. The blade is tested in a flap-wise bending direction with the suction side primarily under compressive stress and pressure side under tensile stress...... tests at a coupon level? What might be the concerns one should take into account when predicting residual structural properties of rotor blades? To answer, at least to a partial extent, these questions, this study conducts a full-scale fatigue test on a 47m composite rotor blade according to IEC 61400......, see Fig. 1. The applied loads are increased to reduce the number of cycles to 2.0 million cycles. Bending stiffness of the blade is measured at different span-wise sections during the fatigue test in order to measure its possible degradation. Natural frequencies and damping ratios are measured both...

  16. Using King Vision video laryngoscope with a channeled blade prolongs time for tracheal intubation in different training levels, compared to non-channeled blade.

    Directory of Open Access Journals (Sweden)

    Marc Kriege

    Full Text Available It is generally accepted that using a video laryngoscope is associated with an improved visualization of the glottis. However, correctly placing the endotracheal tube might be challenging. Channeled video laryngoscopic blades have an endotracheal tube already pre-loaded, allowing to advance the tube once the glottis is visualized. We hypothesized that use of a channel blade with pre-loaded endotracheal tube results in a faster intubation, compared to a curved Macintosh blade video laryngoscope.After ethical approval and informed consent, patients were randomized to receive endotracheal Intubation with either the King Vision® video laryngoscope with curved blade (control or channeled blade (channeled. Success rate, evaluation of the glottis view (percentage of glottic opening (POGO, Cormack&Lehane (C&L and intubating time were evaluated.Over a two-month period, a total of 46 patients (control n = 23; channeled n = 23 were examined. The first attempt success rates were comparable between groups (control 100% (23/23 vs. channeled 96% (22/23; p = 0.31. Overall intubation time was significantly shorter with control (median 40 sec; IQR [24-58], compared to channeled (59 sec [40-74]; p = 0.03. There were no differences in glottis visualization between groups.Compared with the King Vision channeled blade, time for tracheal intubation was shorter with the control group using a non-channeled blade. First attempt success and visualization of the glottis were comparable. These data do not support the hypothesis that a channeled blade is superior to a curved video laryngoscopic blade without tube guidance.ClinicalTrials.gov NCT02344030.

  17. 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

  18. 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

  19. Structural dynamic modeling for rotating blades using three dimensional finite elements

    Energy Technology Data Exchange (ETDEWEB)

    Kee, Young Jung; Shin, Sang Joon [Seoul National University, Seoul (Korea, Republic of)

    2015-04-15

    A precise analysis model was developed in this paper to investigate the dynamic characteristics of rotating composite blades. An eighteen-node solid-shell finite element was used to model the blade structures. This study is focused on geometrically nonlinear problems, because the material is assumed linear elastic. Incremental total Lagrangian approach was adopted to allow estimations on arbitrarily large rotations and displacements. The equations of motion for the finite element model were derived by using Hamilton's principle, and the resulting nonlinear equilibrium equations were solved by applying Newton-Raphson method combined with load control. A modified stress-strain relation was adopted to avoid the transverse shear locking problem, and fairly reliable results were obtained with no sign of locking phenomenon. The obtained numerical results were compared to several benchmark problems, and the results show a good correlation with the experimental data and other finite element analysis results. The vibration characteristics of shell- and beam-type blades were investigated. For shell-type blades, the dynamic characteristics may be significantly influenced by blade curvature, pre-twist, and geometric nonlinearity. For beam-type blades, one-dimensional beam and three-dimensional solid models offer comparable predictions for the straight and large aspect ratio blade. As blade aspect ratio decreases, considerable differences appear in the bending and torsion modes. The tip sweep angle tends to decrease the flap bending frequencies, but the torsion frequency increases with the tip sweep angle.

  20. Structural dynamic modeling for rotating blades using three dimensional finite elements

    International Nuclear Information System (INIS)

    Kee, Young Jung; Shin, Sang Joon

    2015-01-01

    A precise analysis model was developed in this paper to investigate the dynamic characteristics of rotating composite blades. An eighteen-node solid-shell finite element was used to model the blade structures. This study is focused on geometrically nonlinear problems, because the material is assumed linear elastic. Incremental total Lagrangian approach was adopted to allow estimations on arbitrarily large rotations and displacements. The equations of motion for the finite element model were derived by using Hamilton's principle, and the resulting nonlinear equilibrium equations were solved by applying Newton-Raphson method combined with load control. A modified stress-strain relation was adopted to avoid the transverse shear locking problem, and fairly reliable results were obtained with no sign of locking phenomenon. The obtained numerical results were compared to several benchmark problems, and the results show a good correlation with the experimental data and other finite element analysis results. The vibration characteristics of shell- and beam-type blades were investigated. For shell-type blades, the dynamic characteristics may be significantly influenced by blade curvature, pre-twist, and geometric nonlinearity. For beam-type blades, one-dimensional beam and three-dimensional solid models offer comparable predictions for the straight and large aspect ratio blade. As blade aspect ratio decreases, considerable differences appear in the bending and torsion modes. The tip sweep angle tends to decrease the flap bending frequencies, but the torsion frequency increases with the tip sweep angle.

  1. The Analysis of the Aerodynamic Character and Structural Response of Large-Scale Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    2013-06-01

    Full Text Available A process of detailed CFD and structural numerical simulations of the 1.5 MW horizontal axis wind turbine (HAWT blade is present. The main goal is to help advance the use of computer-aided simulation methods in the field of design and development of HAWT-blades. After an in-depth study of the aerodynamic configuration and materials of the blade, 3-D mapping software is utilized to reconstruct the high fidelity geometry, and then the geometry is imported into CFD and structure finite element analysis (FEA software for completely simulation calculation. This research process shows that the CFD results compare well with the professional wind turbine design and certification software, GH-Bladed. Also, the modal analysis with finite element method (FEM predicts well compared with experiment tests on a stationary blade. For extreme wind loads case that by considering a 50-year extreme gust simulated in CFD are unidirectional coupled to the FE-model, the results indicate that the maximum deflection of the blade tip is less than the distance between the blade tip (the point of maximum deflection and the tower, the material of the blade provides enough resistance to the peak stresses the occur at the conjunction of shear webs and center spar cap. Buckling analysis is also included in the study.

  2. 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

  3. Stochastic Analysis of the Influence of Tower Shadow on Fatigue Life of Wind Turbine Blade

    DEFF Research Database (Denmark)

    Pedersen, Ronnie; Nielsen, Søren R.K.; Thoft-Christensen, Palle

    2012-01-01

    Fatigue damage accumulation in upwind turbine blades is primarily influenced by turbulence in the inflow. However, the stress reversals during blade passages through the stagnating and deflected mean wind field in front of the tower also contributes significantly. In the paper the lower order...... statistical moments of the fatigue life of a blade are estimated and compared for a turbine with a tripod tower and a standard mono-tower, respectively. The stagnation zones for each of the legs of the tripod are narrower than for the mono-tower, and hence the stress reversals will be comparable smaller....... The blade stresses are calculated from a dynamic mechanical model based on a two dynamic degree of freedom with quasi-static correction for higher modes. The self-induced aero-elastic loading and the turbulence loading are modeled by means of a quasi-static model linearized around the operational point...

  4. Implementation of a Biaxial Resonant Fatigue Test Method on a Large Wind Turbine Blade

    Energy Technology Data Exchange (ETDEWEB)

    Snowberg, D.; Dana, S.; Hughes, S.; Berling, P.

    2014-09-01

    A biaxial resonant test method was utilized to simultaneously fatigue test a wind turbine blade in the flap and edge (lead-lag) direction. Biaxial resonant blade fatigue testing is an accelerated life test method utilizing oscillating masses on the blade; each mass is independently oscillated at the respective flap and edge blade resonant frequency. The flap and edge resonant frequency were not controlled, nor were they constant for this demonstrated test method. This biaxial resonant test method presented surmountable challenges in test setup simulation, control and data processing. Biaxial resonant testing has the potential to complete test projects faster than single-axis testing. The load modulation during a biaxial resonant test may necessitate periodic load application above targets or higher applied test cycles.

  5. Design of a 21 m blade with Risø-A1 airfoils for active stall controlled wind turbines

    DEFF Research Database (Denmark)

    Fuglsang, Peter; Sangill, O.; Hansen, P.

    2002-01-01

    This is the final report, from the project, "Design of a Rotor/Airfoil Family for Active Stall-regulated Wind Turbines by Use of Multi-point Optimization". It describes the full scale testing of a 21 m wind turbine blade specially designed for active stallregulation. Design objectives were...... increased ratio of produced energy to turbine loads and more stable power control characteristics. Both were taken directly into account during the design of the blade using numerical optimization. The blade used theRisø-A1 airfoil family, which was specially designed for operation on wind turbine blades...... be concluded that the new LM 21.0 ASR blade could replace the LM 21.0P leading to improved cost efficiency and that the Risø-A1 airfoils were well suited for active stall control. With the newestablished knowledge of the actual airfoil characteristics, a possible future blade design could be made also...

  6. On Orientation Control of Suspended Blade During Installation in Wind Turbines

    DEFF Research Database (Denmark)

    Schmidt, Lasse; Roemer, Daniel Beck; Pedersen, Henrik Clemmensen

    2015-01-01

    This paper discusses problems involved in the procedure for offshore installation of blades in wind turbines, due to wind loads. In general the high winds at sea provides for nearly optimal conditions for harvesting energy via wind turbines due to the often high wind speeds and low turbulence...... intensity. However, the very same features also call for great difficulties during installation of the wind turbine blades, making this process extremely difficult, expensive and time consuming. Often the blades are hoisted to the wind turbine hub via cranes and sought held in appropriate positions by so...

  7. Two LQRI based Blade Pitch Controls for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Yoonsu Nam

    2012-06-01

    Full Text Available As the wind turbine size has been increasing and their mechanical components are built lighter, the reduction of the structural loads becomes a very important task of wind turbine control in addition to maximum wind power capture. In this paper, we present a separate set of collective and individual pitch control algorithms. Both pitch control algorithms use the LQR control technique with integral action (LQRI, and utilize Kalman filters to estimate system states and wind speed. Compared to previous works in this area, our pitch control algorithms can control rotor speed and blade bending moments at the same time to improve the trade-off between rotor speed regulation and load reduction, while both collective and individual pitch controls can be designed separately. Simulation results show that the proposed collective and individual pitch controllers achieve very good rotor speed regulation and significant reduction of blade bending moments.

  8. Flutter of a fan blade in supersonic axial flow

    Science.gov (United States)

    Kielb, Robert E.; Ramsey, John K.

    1988-01-01

    An application of a simple aeroelastic model to an advanced supersonic axial flow fan is presented. Lane's cascade theory is used to determine the unsteady aerodynamic loads. Parametric studies are performed to determine the effects of mode coupling, Mach number, damping, pitching axis location, solidity, stagger angle, and mistuning. The results show that supersonic axial flow fan and compressor blades are susceptible to a strong torsional mode flutter having critical reduced velocities which can be less than one.

  9. Is blade element momentum theory (BEM) enough for smart rotor design

    NARCIS (Netherlands)

    Yu, W.; Simao Ferreira, C.J.; van Kuik, G.A.M.

    2014-01-01

    Smart rotor emerges as an innovation technique to reduce the impact of dynamic loading on wind turbines. Local movements of distributed aerodynamic devices will enhance the non-uniformity and dynamic effects of loading, which will challenge the applicability of the blade element momentum theory

  10. Initiation of trailing edge failure in full-scale wind turbine blade test

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich; Branner, Kim

    2016-01-01

    non-linear buckling effect of the trailing edge under combined loading, and how it affects the ultimate strength of a blade in a trailing-edge failure dominated load direction were investigated. The study details the interaction between trailing edge buckling on damage onset and sandwich panel failure...

  11. Using Pretwist to Reduce Power Loss of Bend-Twist Coupled Blades

    DEFF Research Database (Denmark)

    Stäblein, Alexander; Tibaldi, Carlo; Hansen, Morten Hartvig

    2016-01-01

    Bend-twist coupling of wind turbine blades is known as a means to reduce the structural loads of the turbine. While the load reduction is desirable, bend-twist coupling also leads to a decrease in the annual energy production of the turbine. The reduction is mainly related to a no longer optimal...

  12. Independent Blade Pitch Controller Design for a Three-Bladed Turbine Using Disturbance Accommodating Control: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Na; Wright, Alan D.; Johnson, Kathryn E.

    2016-07-29

    Two independent pitch controllers (IPCs) based on the disturbance accommodating control (DAC) algorithm are designed for the three-bladed Controls Advanced Research Turbine to regulate rotor speed and to mitigate blade root flapwise bending loads in above-rated wind speed. One of the DAC-based IPCs is designed based on a transformed symmetrical-asymmetrical (TSA) turbine model, with wind disturbances being modeled as a collective horizontal component and an asymmetrical linear shear component. Another DAC-based IPC is designed based on a multiblade coordinate (MBC) transformed turbine model, with a horizontal component and a vertical shear component being modeled as step waveform disturbance. Both of the DAC-based IPCs are found via a regulation equation solved by Kronecker product. Actuator dynamics are considered in the design processes to compensate for actuator phase delay. The simulation study shows the effectiveness of the proposed DAC-based IPCs compared to a proportional-integral (PI) collective pitch controller (CPC). Improvement on rotor speed regulation and once-per-revolution and twice-per-revolution load reductions has been observed in the proposed IPC designs.

  13. RESEARCH OF THE HIGH HARMONICS INDIVIDUAL BLADE CONTROL EFFECT ON VIBRATIONS CAUSED BY THE HELICOPTER MAIN ROTOR THRUST

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available The paper presents numerical results analysis of main rotor vibration due to helicopter main rotor thrust pulsation.The calculation method, the object of research and numerical research results with the aim to reduce the amplitude of the vibrations transmitted to the hub from the helicopters main rotor by the individual blade control in azimuth by the installation angle of blades cyclic changes are set out in the article. The individual blades control law for a five-blade main rotor based on the blade frequencies is made. It allows reducing the vibration from thrust. Research takes into account the main rotor including and excluding the blade flapping motion. The minimal vibrations regime is identified.Numerical study of variable loads caused by unsteady flow around the main rotor blades at high relative speeds of flight, which transmitted to the rotor hub, is made. The scheme of a thin lifting surface and the rotor vortex theory are used for simulation of the aerodynamic loads on blades. Non - uniform loads caused by the thrust, decomposed on the blade harmonic and its overtones. The largest values of deviation from the mean amplitude thrust are received. The analysis of variable loads with a traditional control system is made. Algorithms of higher harmonics individual blade control capable of reducing the thrust pulsation under the average value of thrust are developed.Numerical research shows that individual blade control of high harmonics reduces variable loads. The necessary change in the blade installation is about ± 0,2 degree that corresponds to the maximum displacement of the additional con- trol stick is about 1 mm.To receive the overall picture is necessary to consider all six components of forces and moments. Control law with own constants will obtained for each of them. It is supposed, that each of six individual blade control laws have an impact on other components. Thus, the problem reduces to the optimization issue. The

  14. The impact of inertial forces on morphing wind turbine blade in vertical axis configuration

    International Nuclear Information System (INIS)

    Butbul, Jonathan; MacPhee, David; Beyene, Asfaw

    2015-01-01

    Highlights: • A novel flexible VAWT has been experimentally tested alongside numerically simulations. • Using FEA and CFD, direction of blade bending was predicted from inertial and aerodynamic forces. • High-speed camera footage has been used to validate the model. • The flexible VAWT was found to self-start in the majority of tests, while the rigid one did not. • It is suggested that flexible VAWTs can have improved performance in part-load applications. - Abstract: A novel flexible blade concept with the ability to morph and geometrically adapt to changing flow conditions has been proposed to improve part-load performance of horizontal-axis wind turbines. The extension of these benefits to a vertical axis wind turbine would make wind technology a more competitive player in the energy market. Both flexible and rigid wind turbine rotor blades for vertical axis application were modeled, designed, manufactured and tested. Their performances were tested in a low speed wind tunnel. The predicted magnitude and direction of blade morph was validated using a high speed camera as well as finite element analysis. The comparative results of straight rigid and straight morphing blades show that the coefficient of performance greatly depends on the tip speed ratio. Overall, the morphing blade has better performance at low RPMs, but the rigid blade performed better at high RPMs. It was observed that the flexible blade self-started in the majority of the experiments. At high RPM, the centrifugal force overwhelmed the lift force, bending the flexible blade out of phase in an undesired direction increasing drag and therefore reducing the coefficient of performance

  15. Behavior of Brittle Materials Under Dynamic Loading

    National Research Council Canada - National Science Library

    Kanel, G

    2000-01-01

    Dynamic loading of brittle materials is related to many applications, including explosive excavation of rocks, design of ceramic armor, meteor impact on spacecraft windows, particle damage to turbine blades, etc...

  16. 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...... are tracked via two radio links using delay-based distance estimation and triangulation. In order to build reliable radio links, time-domain pulse field distributions are simulated to optimize the in-blade tip antenna polarization and the locations of the two root antennas around the root surface. Full......-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...

  17. Non-Harmonic Fourier Analysis for bladed wheels damage detection

    Science.gov (United States)

    Neri, P.; Peeters, B.

    2015-11-01

    The interaction between bladed wheels and the fluid distributed by the stator vanes results in cyclic loading of the rotating components. Compressors and turbines wheels are subject to vibration and fatigue issues, especially when resonance conditions are excited. Even if resonance conditions can be often predicted and avoided, high cycle fatigue failures can occur, causing safety issues and economic loss. Rigorous maintenance programs are then needed, forcing the system to expensive shut-down. Blade crack detection methods are beneficial for condition-based maintenance. While contact measurement systems are not always usable in exercise conditions (e.g. high temperature), non-contact methods can be more suitable. One (or more) stator-fixed sensor can measure all the blades as they pass by, in order to detect the damaged ones. The main drawback in this situation is the short acquisition time available for each blade, which is shortened by the high rotational speed of the components. A traditional Discrete Fourier Transform (DFT) analysis would result in a poor frequency resolution. A Non-Harmonic Fourier Analysis (NHFA) can be executed with an arbitrary frequency resolution instead, allowing to obtain frequency information even with short-time data samples. This paper shows an analytical investigation of the NHFA method. A data processing algorithm is then proposed to obtain frequency shift information from short time samples. The performances of this algorithm are then studied by experimental and numerical tests.

  18. Design of Wind Turbine Blades

    DEFF Research Database (Denmark)

    McGugan, Malcolm

    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...

  19. 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

  20. Advanced LP turbine blade design

    International Nuclear Information System (INIS)

    Jansen, M.; Pfeiffer, R.; Termuehlen, H.

    1990-01-01

    In the 1960's and early 1970's, the development of steam turbines for the utility industry was mainly influenced by the demand for increasing unit sizes. Nuclear plants in particular, required the design of LP turbines with large annulus areas for substantial mass and volumetric steam flows. Since then the development of more efficient LP turbines became an ongoing challenge. Extensive R and D work was performed in order to build efficient and reliable LP turbines often exposed to severe corrosion, erosion and dynamic excitation conditions. This task led to the introduction of an advanced disk-type rotor design for 1800 rpm LP turbines and the application of a more efficient, reaction-type blading for all steam turbine sections including the first stages of LP turbines. The most recent developments have resulted in an advanced design of large LP turbine blading, typically used in the last three stages of each LP turbine flow section. Development of such blading required detailed knowledge of the three dimensional, largely transonic, flow conditions of saturated steam. Also the precise assessment of blade stressing from dynamic conditions, such as speed and torsional resonance, as well as stochastic and aerodynamic excitation is of extreme importance

  1. Fatigue Lifespan of Engine Box Influenced by Fan Blade Out

    Science.gov (United States)

    Qiu, Ju; Shi, Jingwei; Su, Huaizhong; Zhang, Jinling; Feng, Juan; Shi, Qian; Tian, Xiaoyu

    2017-11-01

    This provides precious experience and reliable reference data for future design. This paper introduces the analysis process of Fan-blade-out, and considers the effect of windmill load on the fatigue lifespan of the case. According to Extended Operations (ETOPS) in the airworthiness regulations, the fatigue crack of it is analyzed by the unbalanced rotor load, during FBO. Compared with the lifespan in normal work of the engine, this research provides valuable design experience and reliable reference data for the case design in the near future.

  2. Design and Evaluation of Glass/epoxy Composite Blade and Composite Tower Applied to Wind Turbine

    Science.gov (United States)

    Park, Hyunbum

    2018-02-01

    In the study, the analysis and manufacturing of small class wind turbine blade was performed. In the structural design, firstly the loading conditions are defined through the load case analysis. The proposed structural configuration of blade has a sandwich type composite structure with the E-glass/Epoxy face sheets and the Urethane foam core for lightness, structural stability, low manufacturing cost and easy manufacturing process. And also, this work proposes a design procedure and results of tower for the small scale wind turbine systems. Structural analysis of blade including load cases, stress, deformation, buckling, vibration and fatigue life was performed using the finite element method, the load spectrum analysis and the Miner rule. Moreover, investigation on structural safety of tower was verified through structural analysis by FEM. The manufacturing of blade and tower was performed based on structural design. In order to investigate the designed structure, the structural tests were conducted and its results were compared with the calculated results. It is confirmed that the final proposed blade and tower meet the design requirements.

  3. Dynamic Response of Offshore Wind Turbines subjected to Joint Wave and Wind Loads

    DEFF Research Database (Denmark)

    Liu, Weiliang; Chen, Jianbing; Liu, Wenfeng

    2013-01-01

    into consideration. Wind and wave loads are generated by the physical random models. The aerodynamic loads on blades are calculated by the Blade Element Momentum (BEM) theory, and the wave loads are calculated by the linear theory of wave. The dynamic response of the NREL-5MW wind turbine system is carried out...

  4. Effect of Trailing Edge Damage on Full-Scale Wind Turbine Blade Failure

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich; Branner, Kim

    2015-01-01

    of trailing edge failure is very complex and can arise from manufacturing flaws, damages during transportation and erection as well as under general and extreme operational conditions. The focus in this study is put on the geometrical nonlinear buckling effect of the trailing edge under combined loading...... where the load bearing structure is connected to the shells and at the joints of the upper and lower shells, usually at the leading and trailing edges. Maintenance inspections of wind turbines show that cracks in the vicinity of the trailing edge are typically occurring forms of damage. The cause...... and how it affects the ultimate strength of a holistic blade. For this reason a 34m long blade was studied experimentally and numerically under ultimate load until blade collapse. The interaction between trailing edge buckling on damage onset and sandwich panel failure was studied in detail. Numerically...

  5. Structural modification of a steam turbine blade

    Science.gov (United States)

    Heidari, M.; Amini, K.

    2017-05-01

    Blades are significant components of steam turbines which are failed due to stresses arising from centrifugal and bending forces. The turbine blade has a number of geometrical variables that need to be considered at the design stage. Hence, this paper investigated a three-dimensional model of steam turbine blade with different lengths and thicknesses using finite element method. A three-dimensional model of blade was developed using a computer-aided design software. All materials were assumed linear, homogenous, elastic and isotropic. A 5 N widespread force was applied to the blade. The results of this study showed that longer blades are experienced higher maximum Von Mises stress and strain than shorter ones. The blade with the length of 400 mm and thickness of 20 mm experienced the lowest maximum Von Mises stress at 51 kPa. Furthermore, blade with the length of 400 mm and 600 mm experienced the lowest and highest strain at 3.07 × 10-6 and 4.3 × 10-6 respectively. In addition, thicker blades were undergone less maximum Von Mises stress and strain than thinner ones. Understanding stress and strain pattern in turbine blades provides useful knowledge which can be useful to estimate the fatigue in turbine blades.

  6. Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

    Science.gov (United States)

    Coroneos, Rula M.

    2012-01-01

    This report addresses the structural analysis and optimization of a composite fan blade sized for a large aircraft engine. An existing baseline solid metallic fan blade was used as a starting point to develop a hybrid honeycomb sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replacing the original baseline solid metallic fan model made of titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements, a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized whereas the overall blade thickness is held fixed so as to not alter the original airfoil geometry. Weight is taken as the objective function to be minimized by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

  7. Stability analysis of flexible wind turbine blades using finite element method

    Science.gov (United States)

    Kamoulakos, A.

    1982-08-01

    Static vibration and flutter analysis of a straight elastic axis blade was performed based on a finite element method solution. The total potential energy functional was formulated according to linear beam theory. The inertia and aerodynamic loads were formulated according to the blade absolute acceleration and absolute velocity vectors. In vibration analysis, the direction of motion of the blade during the first out-of-lane and first in-plane modes was examined; numerical results involve NASA/DOE Mod-0, McCauley propeller, north wind turbine and flat plate behavior. In flutter analysis, comparison cases were examined involving several references. Vibration analysis of a nonstraight elastic axis blade based on a finite element method solution was performed in a similar manner with the straight elastic axis blade, since it was recognized that a curved blade can be approximated by an assembly of a sufficient number of straight blade elements at different inclinations with respect to common system of axes. Numerical results involve comparison between the behavior of a straight and a curved cantilever beam during the lowest two in-plane and out-of-plane modes.

  8. Detailed On-Water Measurements of Blade Forces and Stroke Efficiencies in Sprint Canoe

    Directory of Open Access Journals (Sweden)

    Stephen Tullis

    2018-03-01

    Full Text Available Measurements of blade forces are made using a load cell mounted between the blade and shaft of a modified paddle. All six force components and moments are measured simultaneously to give a full picture of blade hydrodynamic forces as the centre of pressure on the blade varies throughout the stroke. Blade orientation was also measured using inertial measurement units, one on the blade shaft, and the other on the canoe giving the relative position of blade with respect to the boat, as well as boat speed, acceleration and motion. Testing of the instrumented paddle was undertaken by one of the authors, an ex-national team athlete. The measured forces (and propulsive/vertical forces are analyzed in detail through the stroke and as stroke averages. Various measures of propulsive efficiency are proposed using either the input force and propulsive force, or using input force and boat speed, and can be used for stroke analysis, or as training tools/targets.

  9. Crack modeling of rotating blades with cracked hexahedral finite element method

    Science.gov (United States)

    Liu, Chao; Jiang, Dongxiang

    2014-06-01

    Dynamic analysis is the basis in investigating vibration features of cracked blades, where the features can be applied to monitor health state of blades, detect cracks in an early stage and prevent failures. This work presents a cracked hexahedral finite element method for dynamic analysis of cracked blades, with the purpose of addressing the contradiction between accuracy and efficiency in crack modeling of blades in rotor system. The cracked hexahedral element is first derived with strain energy release rate method, where correction of stress intensity factors of crack front and formulation of load distribution of crack surface are carried out to improve the modeling accuracy. To consider nonlinear characteristics of time-varying opening and closure effects caused by alternating loads, breathing function is proposed for the cracked hexahedral element. Second, finite element method with contact element is analyzed and used for comparison. Finally, validation of the cracked hexahedral element is carried out in terms of breathing effects of cracked blades and natural frequency in different crack depths. Good consistency is acquired between the results with developed cracked hexahedral element and contact element, while the computation time is significantly reduced in the previous one. Therefore, the developed cracked hexahedral element achieves good accuracy and high efficiency in crack modeling of rotating blades.

  10. Blade bowing effects on radial equilibrium of inlet flow in axial compressor cascades

    Directory of Open Access Journals (Sweden)

    Han XU

    2017-10-01

    Full Text Available The circumferentially averaged equation of the inlet flow radial equilibrium in axial compressor was deduced. It indicates that the blade inlet radial pressure gradient is closely related to the radial component of the circumferential fluctuation (CF source item. Several simplified cascades with/without aerodynamic loading were numerically studied to investigate the effects of blade bowing on the inlet flow radial equilibrium. A data reduction program was conducted to obtain the CF source from three-dimensional (3D simulation results. Flow parameters at the passage inlet were focused on and each term in the radial equilibrium equation was discussed quantitatively. Results indicate that the inviscid blade force is the inducement of the inlet CF due to geometrical asymmetry. Blade bowing induces variation of the inlet CF, thus changes the radial pressure gradient and leads to flow migration before leading edge (LE in the cascades. Positive bowing drives the inlet flow to migrate from end walls to mid-span and negative bowing turns it to the reverse direction to build a new equilibrium. In addition, comparative studies indicate that the inlet Mach number and blade loading can efficiently impact the effectiveness of blade bowing on radial equilibrium in compressor design.

  11. Experimental study to the influences of rotational speed and blade shape on water vortex turbine performance

    Science.gov (United States)

    Kueh, T. C.; Beh, S. L.; Ooi, Y. S.; Rilling, D. G.

    2017-04-01

    Water vortex turbine utilizes the natural behaviour of water to form free surface vortex for energy extraction. This allows simple construction and ease of management on the whole water vortex power plant system. To our findings, the literature study specifically on water vortex turbine is inadequate and low efficiency was reported. Influences of operating speed and blade shape on turbine performance are the two parameters investigated in this study. Euler Turbomachinery Equation and velocity triangle are used in the improvement analysis. Two turbines with flat blades and curved blades are tested and compared. Both turbines show similar rotational speed at no load condition. This suggested that the circulation force of the water vortex has more dominant effect on the turbine rotational speed, compared to the turbine’s geometry. Flat-blades turbine showed maximum efficiency of 21.63% at 3.27 rad/s whereas curved-blades turbine showed 22.24% at 3.56 rad/s. When operating load is applied, the backward-leaning curve helps the turbine blades to reduce the disturbance on the water vortex, and hence provide a better performance.

  12. Influence of Reynolds Number on Multi-Objective Aerodynamic Design of a Wind Turbine Blade.

    Science.gov (United States)

    Ge, Mingwei; Fang, Le; Tian, De

    2015-01-01

    At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project.

  13. Active Control of a Small-Scale Wind Turbine Blade Containing Magnetorheological Fluid

    Directory of Open Access Journals (Sweden)

    Fevzi Cakmak Bolat

    2018-02-01

    Full Text Available This research study proposes a new active control structure to suppress vibrations of a small-scale wind turbine blade filled with magnetorheological (MR fluid and actuated by an electromagnet. The aluminum blade structure is manufactured using the SH3055 (Bergey Windpower Co. Inc., Norman, OK, USA code numbered airfoil which is designed for use on small wind turbines. A dynamic interaction model between the MR fluid and the electromagnetic actuator is constructed to obtain a force relation. A detailed characterization study is presented for the proposed actuator to understand the nonlinear behavior of the electromagnetic force. A norm based multi-objective H2/H∞ controller is designed using the model of the elastic blade element. The H2/H∞ controller is experimentally implemented under the impact and steady state aerodynamic load conditions. The results of experiments show that the MR fluid- electromagnetic actuator is effective for suppressing vibrations of the blade structure.

  14. Active Tuned Mass Dampers for Control of In-Plane Vibrations of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Fitzgerald, B.; Basu, Biswajit; Nielsen, Søren R.K.

    2013-01-01

    This paper investigates the use of active tuned mass dampers (ATMDs) for the mitigation of in-plane vibrations in rotating wind turbine blades. The rotating wind turbine blades with tower interaction represent time-varying dynamical systems with periodically varying mass, stiffness, and damping...... for this purpose, which considers the structural dynamics of the system and the interaction between in-plane and out-of-plane vibrations. Also, the interaction between the blades and the tower including the tuned mass dampers is considered. The wind turbine with tuned mass dampers was subjected to gravity......, centrifugal, and turbulent aerodynamic loadings. Investigations show promising results for the use of ATMDs in the vibration control of wind turbine blades....

  15. Visualization of the elastic blade motion of an operating wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Ronsten, Goeran

    2005-04-01

    Blade elastic displacement were successfully tracked by means of digital photographic recording using both Light Emitting Diods; LEDs, and reflexes mounted on a wind turbine blade. A procedure for image analysis was developed. The output from the image analysis was co-ordinates of the objects under investigation. Although the method developed is useful in producing results it still remains to verify the integrity of the results versus, for example, load measurements. The image analysis carried out and presented in this report shows that verification of simulation of blade movements is attainable. However, exact outdoor inflow conditions are extremely difficult to measure and it is therefore not possible to emulate every situation in detail. An increased knowledge of actual blade translation and rotation will nevertheless enable improvement of structural dynamics simulation codes. This is an insight which will grow with the size of future turbines.

  16. Effect of Turbulence on Power for Bend-Twist Coupled Blades

    DEFF Research Database (Denmark)

    Stäblein, Alexander; Hansen, Morten Hartvig

    2016-01-01

    that it might be related to the dynamic response of bend-twist coupled blades in turbulent flow. This paper contains estimations of the power curve from nonlinear time simulations, a linear frequency domain based method and a normal distribution weighted average method. It is shown that the frequency domain...... that changes in power due to turbulence are similar for coupled and uncoupled blades. Power gains at low wind speeds are related to the curvature of the steady state power curve. Losses around rated wind speed are caused by the effects of controller switching between partial and full power operation.......Bend-twist coupling of wind turbine blades reduces the structural loads of the turbine but it also results in a decrease of the annual energy production. The main part of the power loss can be mitigated by pretwisting the blade, but some power loss remains and previous studies indicate...

  17. Intubation of prehospital patients with curved laryngoscope blade is more successful than with straight blade.

    Science.gov (United States)

    Alter, Scott M; Haim, Eithan D; Sullivan, Alex H; Clayton, Lisa M

    2018-02-17

    Direct laryngoscopy can be performed using curved or straight blades, and providers usually choose the blade they are most comfortable with. However, curved blades are anecdotally thought of as easier to use than straight blades. We seek to compare intubation success rates of paramedics using curved versus straight blades. Design: retrospective chart review. hospital-based suburban ALS service with 20,000 annual calls. prehospital patients with any direct laryngoscopy intubation attempt over almost 9years. First attempt and overall success rates were calculated for attempts with curved and straight blades. Differences between the groups were calculated. 2299 patients were intubated by direct laryngoscopy. 1865 had attempts with a curved blade, 367 had attempts with a straight blade, and 67 had attempts with both. Baseline characteristics were similar between groups. First attempt success was 86% with a curved blade and 73% with a straight blade: a difference of 13% (95% CI: 9-17). Overall success was 96% with a curved blade and 81% with a straight blade: a difference of 15% (95% CI: 12-18). There was an average of 1.11 intubation attempts per patient with a curved blade and 1.13 attempts per patient with a straight blade (2% difference, 95% CI: -3-7). Our study found a significant difference in intubation success rates between laryngoscope blade types. Curved blades had higher first attempt and overall success rates when compared to straight blades. Paramedics should consider selecting a curved blade as their tool of choice to potentially improve intubation success. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Mechanisms and actuators for rotorcraft blade morphing

    Science.gov (United States)

    Vocke, Robert D., III

    The idea of improved fight performance through changes in the control surfaces dates back to the advent of aviation with the Wright brothers' pioneering work on "wing warping," but it was not until the recent progress in material and actuator development that such control surfaces seemed practical for modern aircraft. This has opened the door to a new class of aircraft that have the ability to change shape or morph, which are being investigated due to the potential to have a single platform serve multiple mission objectives, as well as improve performance characteristics. While the majority of existing research for morphing aircraft has focused on fixedwing aircraft, rotary-wing aircraft have begun to receive more attention. The purpose of this body of work is to investigate the current state of morphing actuation technology for rotorcraft and improve upon it. Specifically, this work looks at two types of morphing: Pneumatic Artificial Muscle (PAM) actuated trailing edge flaps and conformal variable diameter morphing. First, active camber changes through the use of PAM powered trailing edge flaps were investigated due to the potential for reductions in power requirements and vibration/noise levels. A PAM based antagonistic actuation system was developed utilizing a novel combination of mechanism geometry and PAM bias contraction optimization to overcome the natural extension stiffening characteristics of PAMs. In open-loop bench-top testing against a "worst-case" constant torsional loading, the system demonstrated actuation authority suitable for both primary control and vibration/noise reduction. Additionally, closed-loop test data indicated that the system was capable of tracking complex waveforms consistent with those needed for rotorcraft control. This system demonstrated performance on-par with the state of the art pneumatic trailing edge flap actuators, yet with a much smaller footprint and impact on the rotor-blade. The second morphing system developed in

  19. Structural health monitoring of wind turbine blades : SE 265 Final Project.

    Energy Technology Data Exchange (ETDEWEB)

    Barkley, W. C.(Walter C.); Jacobs, Laura D.; Rutherford, A. C.(Amanda C.); Puckett, Anthony

    2006-03-23

    ACME Wind Turbine Corporation has contacted our dynamic analysis firm regarding structural health monitoring of their wind turbine blades. ACME has had several failures in previous years. Examples are shown in Figure 1. These failures have resulted in economic loss for the company due to down time of the turbines (lost revenue) and repair costs. Blade failures can occur in several modes, which may depend on the type of construction and load history. Cracking and delamination are some typical modes of blade failure. ACME warranties its turbines and wishes to decrease the number of blade failures they have to repair and replace. The company wishes to implement a real time structural health monitoring system in order to better understand when blade replacement is necessary. Because of warranty costs incurred to date, ACME is interested in either changing the warranty period for the blades in question or predicting imminent failure before it occurs. ACME's current practice is to increase the number of physical inspections when blades are approaching the end of their fatigue lives. Implementation of an in situ monitoring system would eliminate or greatly reduce the need for such physical inspections. Another benefit of such a monitoring system is that the life of any given component could be extended since real conditions would be monitored. The SHM system designed for ACME must be able to operate while the wind turbine is in service. This means that wireless communication options will likely be implemented. Because blade failures occur due to cyclic stresses in the blade material, the sensing system will focus on monitoring strain at various points.

  20. Design of Linear Control System for Wind Turbine Blade Fatigue Testing

    Science.gov (United States)

    Toft, Anders; Roe-Poulsen, Bjarke; Christiansen, Rasmus; Knudsen, Torben

    2016-09-01

    This paper proposes a linear method for wind turbine blade fatigue testing at Siemens Wind Power. The setup consists of a blade, an actuator (motor and load mass) that acts on the blade with a sinusoidal moment, and a distribution of strain gauges to measure the blade flexure. Based on the frequency of the sinusoidal input, the blade will start oscillating with a given gain, hence the objective of the fatigue test is to make the blade oscillate with a controlled amplitude. The system currently in use is based on frequency control, which involves some non-linearities that make the system difficult to control. To make a linear controller, a different approach has been chosen, namely making a controller which is not regulating on the input frequency, but on the input amplitude. A non-linear mechanical model for the blade and the motor has been constructed. This model has been simplified based on the desired output, namely the amplitude of the blade. Furthermore, the model has been linearised to make it suitable for linear analysis and control design methods. The controller is designed based on a simplified and linearised model, and its gain parameter determined using pole placement. The model variants have been simulated in the MATLAB toolbox Simulink, which shows that the controller design based on the simple model performs adequately with the non-linear model. Moreover, the developed controller solves the robustness issue found in the existent solution and also reduces the needed energy for actuation as it always operates at the blade eigenfrequency.

  1. Eutectic Composite Turbine Blade Development

    Science.gov (United States)

    1976-11-01

    Eutectic alloys evaluated included MC (metallic carbide ) fiber reinforced nickel- and cobalt -base eutectics (NiTaC and CoTaC) and NisCb lamella reinforced...blade superalloy . The results in Figure 68 indicated that carbide defect structures tend to decrease 1500CHCF strength somewhat, but all...Surface finishes were in the range of 5 to 15 AA. Drilling - Parallel tests were made with carbide and cobalt H.S.S. drills under conditions listed in

  2. Aerodynamical calculation of turbomachinery bladings

    International Nuclear Information System (INIS)

    Fruehauf, H.H.

    1978-01-01

    Various flow models are presented in comparison to one another, these flow models being obtained from the basic equations of turbomachinery aerodynamics by means of a series of simplifying assumptions on the spatial distribution of the flow quantities. The simplifying assumptions are analysed precisely. With their knowledge it is possible to construct more accurate simplified flow models, which are necessary for the efficient aerodynamical development of highperformance turbomachinery bladings by means of numerical methods. (orig.) 891 HP [de

  3. Load alleviation of wind turbines by yaw misalignment

    DEFF Research Database (Denmark)

    Kragh, Knud Abildgaard; Hansen, Morten Hartvig

    2014-01-01

    Vertical wind shear is one of the dominating causes of load variations on the blades of a horizontal axis wind turbine. To alleviate the varying loads, wind turbine control systems have been augmented with sensors and actuators for individual pitch control. However, the loads caused by a vertical...... wind shear can also be affected through yaw misalignment. Recent studies of yaw control have been focused on improving the yaw alignment to increase the power capture at below rated wind speeds. In this study, the potential of alleviating blade load variations induced by the wind shear through yaw...... be applied without power loss for wind speeds above rated wind speed. In deterministic inflow, it is shown that the range of the steady-state blade load variations can be reduced by up to 70%. For turbulent inflows, it is shown that the potential blade fatigue load reductions depend on the turbulence level...

  4. Load prediction of stall regulated wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerck, A.; Dahlberg, J.Aa. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Carlen, I. [Chalmers Univ. of Technology, Goeteborg (Sweden). Div. of Marine Structural Engineering; Ganander, H. [Teknikgruppen AB, Sollentua (Sweden)

    1996-12-01

    Measurements of blade loads on a turbine situated in a small wind farm shows that the highest blade loads occur during operation close to the peak power i.e. when the turbine operates in the stall region. In this study the extensive experimental data base has been utilised to compare loads in selected campaigns with corresponding load predictions. The predictions are based on time domain simulations of the wind turbine structure, performed by the aeroelastic code VIDYN. In the calculations a model were adopted in order to include the effects of dynamic stall. This paper describes the work carried out so far within the project and key results. 5 refs, 10 figs

  5. A New Energy-Critical Plane Damage Parameter for Multiaxial Fatigue Life Prediction of Turbine Blades

    Directory of Open Access Journals (Sweden)

    Zheng-Yong Yu

    2017-05-01

    Full Text Available As one of fracture critical components of an aircraft engine, accurate life prediction of a turbine blade to disk attachment is significant for ensuring the engine structural integrity and reliability. Fatigue failure of a turbine blade is often caused under multiaxial cyclic loadings at high temperatures. In this paper, considering different failure types, a new energy-critical plane damage parameter is proposed for multiaxial fatigue life prediction, and no extra fitted material constants will be needed for practical applications. Moreover, three multiaxial models with maximum damage parameters on the critical plane are evaluated under tension-compression and tension-torsion loadings. Experimental data of GH4169 under proportional and non-proportional fatigue loadings and a case study of a turbine disk-blade contact system are introduced for model validation. Results show that model predictions by Wang-Brown (WB and Fatemi-Socie (FS models with maximum damage parameters are conservative and acceptable. For the turbine disk-blade contact system, both of the proposed damage parameters and Smith-Watson-Topper (SWT model show reasonably acceptable correlations with its field number of flight cycles. However, life estimations of the turbine blade reveal that the definition of the maximum damage parameter is not reasonable for the WB model but effective for both the FS and SWT models.

  6. Parametric dependence of a morphing wind turbine blade on material elasticity

    International Nuclear Information System (INIS)

    Puterbaugh, Martin; Beyene, Asfaw

    2011-01-01

    A few recent works have suggested a morphing blade for wind turbine energy conversion. The concept is derived from fin and wing motions that better adapt to varying load conditions. Previous research has provided the fluid mechanic justification of this new concept. This paper establishes a parametric relationship between an asymmetric wind turbine blade and constituent material modulus to predict the geometric response of the morphing blade for a given material characteristic. The airfoil's trailing edge deflection is associated to a prescribed fluid exit angle via the Moment Area (MA) method. Subsequently, a mathematical model is derived to predict material deformation with respect to imparted aerodynamic forces. Results show that an airfoil, much like a tapered beam, can be modeled as a non-prismatic cantilevered beam using this well established method. -- Research highlights: →A mathematical model relating morphing airfoil thickness and elastic modulus was established. →For non-prismatic beam under a uniform distributive load, the slope and deflection of the airfoil's trailing edge were related to the fluid exit angle. →The main driver of blade deformation was the angular drag force. The Moment Area method was used, verified by Finite Element method. →Displacement to the exit angle is predicated upon the elastic modulus value given that other parameters are constant. →Optimum power output is obtained in part load conditions when the blade deforms to the applicable exit angle.

  7. 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.

  8. Relieving loading on tidal turbines operating in a turbulent environment: proposal for load alleviation device for a marine turbine

    OpenAIRE

    Garden, Sarah Rosaline

    2016-01-01

    Tidal turbines operate in marine currents characterised by strong turbulence. This environment impacts on the life of the device, blades, transmission and running train ancillaries, bearings and seals, for example. The reduction of the transient load on the turbine blade can be achieved through a range of measures; in this investigation, modifications to the blade comprising blowing actuators will be modelled using the FLUENT CFD RANS solver with the k-ω SST turbulence model. ...

  9. Fan blade crack diagnosis method study

    Directory of Open Access Journals (Sweden)

    Sheng Fu

    2016-05-01

    Full Text Available This article presents a discrete mathematical model for fan blades and theoretically analyses the mathematical relationship between the location and depth of crack and fan blade natural frequency. On the basis of the blade mathematical model, using the theoretical computed natural frequency as the fault feature, this article proposes a fast and efficient fan blade crack fault diagnosis method. Transfer matrix method is used to calculate the first three-order blade natural frequencies under different crack cases and then to build the database in MATLAB. Subsequently, the damaged blade can be detected using changes in natural frequencies by solving the reverse problem. The experimental result shows that this discrete mathematical model can get the exact solution of natural frequency, and the method has certain application value.

  10. FOD impact testing of composite fan blades

    Science.gov (United States)

    Johns, R. H.

    1974-01-01

    The results of impact tests on large, fiber composite fan blades for aircraft turbofan engine applications are discussed. Solid composite blades of two different sizes and designs were tested. Both graphite/epoxy and boron/epoxy were evaluated. In addition, a spar-shell blade design was tested that had a boron/epoxy shell bonded to a titanium spar. All blades were tested one at a time in a rotating arm rig to simulate engine operating conditions. Impacting media included small gravel, two inch diameter ice balls, gelatin, and RTV foam-simulated birds, as well as starlings and pigeons. The results showed little difference in performance between the graphite and boron/epoxy blades. The results also indicate that composite blades may be able to tolerate ice ball and small bird impacts but need improvement to tolerate birds in the small duck and larger category.

  11. Impact testing on composite fan blades

    Science.gov (United States)

    Johns, R. H.

    1974-01-01

    The results of impact tests on large, fiber composite fan blades for aircraft turbofan engine applications are discussed. Solid composite blades of two different sizes and designs were tested. Both graphite/epoxy and boron/epoxy were evaluated. In addition, a spar-shell blade design was tested that had a boron/epoxy shell bonded to a titanium spar. All blades were tested one at a time in a rotating arm rig to simulate engine operating conditions. Impacting media included small gravel, two inch diameter ice balls, gelatin and RTV foam-simulated birds, as well as starlings and pigeons. The results showed little difference in performance between the graphite and boron/epoxy blades. The results also indicate that composite blades may be able to tolerate ice ball and small bird impacts but need improvement to tolerate birds in the small duck and larger category.

  12. Design and Analysis of Wind Turbine Blade Hub using Aluminium Alloy AA 6061-T6

    Science.gov (United States)

    Ravikumar, S.; Jaswanthvenkatram, V.; Sai kumar, Y. J. N. V.; Sohaib, S. Md.

    2017-05-01

    This work presents the design and analysis of horizontal axis wind turbine blade hub using different material. The hub is very crucial part of the wind turbine, which experience the loads from the blades and the loads were transmitted to the main shaft. At present wind turbine is more expensive and weights more than a million pounds, with the nacelle, rotor hub and blades accounting for most of the weight. In this work Spheroidal graphite cast iron GGG 40.3 is replaced by aluminium alloy 6061-T6 to enhance the casting properties and also to improve the strength-weight ratio. This transition of material leads to reduction in weight of the wind turbine. All the loads caused by wind and extreme loads on the blades are transferred to the hub. Considering the IEC 61400-1 standard for defining extreme loads on the hub the stress and deflection were calculated on the hub by using Finite element Analysis. Result obtained from ANSYS is compared and discussed with the existing design.

  13. HLH Rotor Blade Manufacturing Technology Development Report

    Science.gov (United States)

    1977-09-01

    length, and weighing approximately 350 pounds, is the largest blade presently produced at Boeing Vertol. A blade of this size can still oe manually ...to check contour during core siachining. The fairings will have a trim operacion added to remove the rough edges along the skin. 142 The assembly will...through-transmission evaluation required that the root end specimen be filled -,tith water and the search unit be manipulated manually .) BLADE

  14. Measuring Fan-Blade-Tip Displacements

    Science.gov (United States)

    Berry, Robert F., Jr.

    1988-01-01

    Magnets and Hall-effect transducers used to monitor tip-to-shroud clearances. Mounting permanent magnet in end of fan blade and monitoring tip-to-shroud distance by use of output of Hall-effect transducers affixed to surface of shroud. Transducers provide real-time information. By placing magnets in each fan-blade tip, complete set monitored sequentially as each blade rotates past sensor. Application in many rotating machines, providing surrounding materials nonmagnetic and temperatures not severe.

  15. Fan Blade Deflection Measurement and Analyses Correlation

    Science.gov (United States)

    Mehmed, Oral; Janetzke, David C.

    1997-01-01

    Steady deflection measurements were taken of two identical NASA/Pratt & Whitney-designed fan blades while they were rotating in a vacuum in NASA Lewis Research Center's Dynamic Spin Facility. The one-fifth-scale fan blades, which have a tip diameter of 22 in. and a pinroot retention, are of sparshell construction and were unducted for this test. The purpose of the test was to measure the change of the radial deflection of the blade tip and blade angle at selected radial stations along the blade span with respect to rotational speed. The procedure for radial deflection measurement had no precedent and was newly developed for this test. Radial deflection measurements were made to assure adequate tip clearance existed between the fan blades and the duct for a follow-on wind tunnel test. Also, blade angle deflection measurements were desired before pitchsetting parts for the wind tunnel test were finish machined. During the test, laser beams were aimed across the blade path into photodiodes to give signals that were used to determine blade angle change or tip radial deflection. These laser beams were set parallel to the spin axis at selected radial stations.

  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...... crack growth at loads well below the load-carrying capacity of the beam. The findings in this paper are twofold: Firstly, the investigated analysis procedure can be integrated into the design process of wind turbine blade cross sections. Secondly, the proposed approach serves as a basis...... for computationally efficient numerical analysis approaches of structures that comprise complex geometry and anisotropic material behaviour – such as wind turbine rotor blades....

  17. Design and test of box girder for a large wind turbine blade

    DEFF Research Database (Denmark)

    Nielsen, Per Hørlyk; Tesauro, Angelo; Bitsche, Robert

    , which create an inner structure in the box girder. With a combination of advanced FEM analysis and the inventions it was possible to reduce the material thickness of the cap by up to 40%. The new design of the box girder was manufactured at SSP Technology A/S, where it was demonstrated......This report is covering the structural design and full scale test of a box girder as a part of the project “Demonstration of new blade design using manufacturing process simulations” supported by the EUDP program. A box girder with a predetermined outer geometry was designed using new inventions...... that the manufacturing process could include the new inventions. Subsequently the box girder was transported to the blade test facility at DTU Wind Energy. A series of test was performed with the blade to investigate the behaviour during loading, and finally the girder was loaded to ultimate failure. The report includes...

  18. Theory/test correlation of helicopter rotor blade element airloads in the blade stall regime

    Science.gov (United States)

    Bobo, C. J.

    1972-01-01

    The effects of stall on a rotor blade element in a three-dimensional rotating environment was investigated. The model rotor test provided blade element airloads and local boundary layer flow characteristics at the three-quarter blade radius position for a wide range of rotor operating conditions. A description of the test program and the test results are presented.

  19. Output characteristics of torsion arc blade type horizontal axis windmill; Nejire enko yokugata suiheijiku fusha no shutsuryoku tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, N.; Kishimura, K. [Meiji University, Tokyo (Japan)

    1997-11-25

    The previous paper theoretically analyzes characteristics of a torsion arc blade type (TABT) horizontal axis windmill to derive the theoretical equations, which give the results in good agreement with the observed ones, when multiplied by a blade shape factor. This paper discusses that the theoretical and observed results are in good agreement with each other by taking into consideration shape-related solidity and number of blades. The following findings are obtained, when parameters related to a 6-blade TABT horizontal axis wind mill are introduced and hysteresis brake is used as the load resistance for torque measurement. Shape factor can be represented by two factors of blade number and solidity. The same equation for shape factor is applicable to both elliptical and rectangular blades. These blades need different theoretical equations to give the results in agreement with the observed ones, when operated at a tip speed ratio (TSR) of 1.77 and 1.58, respectively. Rotational force is affected by the rear blade shape when they are operated at a respective TSR below the above level, but unaffected at beyond the above level. 5 refs., 9 figs., 1 tab.

  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. Energy saving in a deep well pump with splitter blade

    Energy Technology Data Exchange (ETDEWEB)

    Goelcue, Mustafa [Department of Mechanical Education, Pamukkale University, 20017 Kinikli, Denizli (Turkey)]. E-mail: mgolcu@pamukkale.edu.tr; Pancar, Yasar [Department of Mechanical Engineering, Osman Gazi University, 26480 Eskisehir (Turkey); Sekmen, Yakup [Karabuk Vocational Collage, Zonguldak Karaelmas University, 78100 Karabuk (Turkey)

    2006-03-15

    Design parameters, like blade number, blade outlet angle and impeller outlet diameter, affect pump performance and energy consumption. Deep well pumps with splitter blades (DWPwsb) are manufactured to achieve energy saving and improve efficiency. Splitter blades are generally located at the centerline of the main blades. Blade number and blade discharge angle should be conveniently determined when splitter blades are used on the impellers. In this study, impellers having different numbers of blades (z = 5, 6, 7) with and without splitter blades (35%, 60% and 80% of the main blade length) were tested in a deep well pump. Tests have been conducted on a total of 12 impellers, and the characteristics of deep well pumps without splitter blade (DWPwosb) and DWPwsb were obtained experimentally. These results show that splitter blades cause negative effects on pump performance in impellers with blade numbers of 6 and 7. When the splitter blade is added to the impeller with the blade number of 5, the efficiency increases with flow up to 10 l/s flow rate, after which it decreases as the splitter blade length increases. The highest efficiency and the lowest energy consumption were obtained in DWPwsb with 80% of the main blade length. At the best efficiency point (b.e.p), an energy saving of 6.6% and an improvement of 1.14% in efficiency were achieved. An analysis of the additional cost of the splitter blade and the application in an agricultural area were performed.

  2. Energy saving in a deep well pump with splitter blade

    International Nuclear Information System (INIS)

    Goelcue, Mustafa; Pancar, Yasar; Sekmen, Yakup

    2006-01-01

    Design parameters, like blade number, blade outlet angle and impeller outlet diameter, affect pump performance and energy consumption. Deep well pumps with splitter blades (DWPwsb) are manufactured to achieve energy saving and improve efficiency. Splitter blades are generally located at the centerline of the main blades. Blade number and blade discharge angle should be conveniently determined when splitter blades are used on the impellers. In this study, impellers having different numbers of blades (z = 5, 6, 7) with and without splitter blades (35%, 60% and 80% of the main blade length) were tested in a deep well pump. Tests have been conducted on a total of 12 impellers, and the characteristics of deep well pumps without splitter blade (DWPwosb) and DWPwsb were obtained experimentally. These results show that splitter blades cause negative effects on pump performance in impellers with blade numbers of 6 and 7. When the splitter blade is added to the impeller with the blade number of 5, the efficiency increases with flow up to 10 l/s flow rate, after which it decreases as the splitter blade length increases. The highest efficiency and the lowest energy consumption were obtained in DWPwsb with 80% of the main blade length. At the best efficiency point (b.e.p), an energy saving of 6.6% and an improvement of 1.14% in efficiency were achieved. An analysis of the additional cost of the splitter blade and the application in an agricultural area were performed

  3. 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...

  4. Revealing fatigue damage evolution in unidirectional composites for wind turbine blades using x-ray computed tomography

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard

    ’. Thereby, it will be possible to lower the cost of energy for wind energy based electricity. In the presented work, a lab-source x-ray computed tomography equipment (Zeiss Xradia 520 Versa) has been used in connection with ex-situ fatigue testing of uni-directional composites in order to identify fibre...... failure during the fatigue loading. The load carrying laminates in wind turbine blades is typically based on a number of non-crimp fabrics in where the load carrying fibres are oriented in the axial direction of the blades. In order to ease the handling of the fabric during the dry fabric layup...

  5. Study on Blade Fatigue Life of Rotating Power Machinery

    Directory of Open Access Journals (Sweden)

    Fu Xi

    2016-01-01

    Full Text Available The linear damage model (LDM is widely applied in engineering calculation, but it does not consider the relationship between damage variable and load parameters. Therefore, the life prediction based on LDM is not satisfied for the aero-engine blades. Besides, it easily brings about error in predicting fatigue life by common nonlinear damage model which neglect the influence of torsional stress. Hence, a modified nonlinear continuum damage model (CDM is put forward based on Chaboche nonlinear damage model in this research. And to determine the damage and fatigue life of TC4 material used in aero-engine blades, axial tension and compression fatigue test is conducted. Compared with LDM results, the fatigue life prediction results of the modified CDM in this work show a good agreement with the tests data. So the correctness of the modified model is verified. Finally, the fatigue life of a certain aero-engine high pressure compressor blade is predicted by the modified nonlinear continuum damage model.

  6. Parametric study of turbine NGV blade lean and vortex design

    Directory of Open Access Journals (Sweden)

    Zhang Shaowen

    2016-02-01

    Full Text Available The effects of blade lean and vortex design on the aerodynamics of a turbine entry nozzle guide vane (NGV are considered using computational fluid dynamics. The aim of the work is to address some of the uncertainties which have arisen from previous studies where conflicting results have been reported for the effect on the NGV. The configuration was initially based on the energy efficient engine turbine which also served as the validation case for the computational method. A total of 17 NGV configurations were evaluated to study the effects of lean and vortex design on row efficiency and secondary kinetic energy. The distribution of mass flow ratio is introduced as an additional factor in the assessment of blade lean effects. The results show that in the turbine entry NGV, the secondary flow strength is not a dominant factor that determines NGV losses and therefore the changes of loading distribution due to blade lean and the associated loss mechanisms should be regarded as a key factor. Radial mass flow redistribution under different NGV lean and twist is demonstrated as an addition key factor influencing row efficiency.

  7. Reinforced wind turbine blades--an environmental life cycle evaluation.

    Science.gov (United States)

    Merugula, Laura; Khanna, Vikas; Bakshi, Bhavik R

    2012-09-04

    A fiberglass composite reinforced with carbon nanofibers (CNF) at the resin-fiber interface is being developed for potential use in wind turbine blades. An energy and midpoint impact assessment was performed to gauge impacts of scaling production to blades 40 m and longer. Higher loadings force trade-offs in energy return on investment and midpoint impacts relative to the base case while remaining superior to thermoelectric power generation in these indicators. Energy-intensive production of CNFs forces impacts disproportionate to mass contribution. The polymer nanocomposite increases a 2 MW plant's global warming potential nearly 100% per kWh electricity generated with 5% CNF by mass in the blades if no increase in electrical output is realized. The relative scale of impact must be compensated by systematic improvements whether by deployment in higher potential zones or by increased life span; the trade-offs are expected to be significantly lessened with CNF manufacturing maturity. Significant challenges are faced in evaluating emerging technologies including uncertainty in future scenarios and process scaling. Inventories available for raw materials and monte carlos analysis have been used to gain insight to impacts of this development.

  8. 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.

  9. Water Flow Testing and Unsteady Pressure Analysis of a Two-Bladed Liquid Oxidizer Pump Inducer

    Science.gov (United States)

    Schwarz, Jordan B.; Mulder, Andrew; Zoladz, Thomas

    2011-01-01

    The unsteady fluid dynamic performance of a cavitating two-bladed oxidizer turbopump inducer was characterized through sub-scale water flow testing. While testing a novel inlet duct design that included a cavitation suppression groove, unusual high-frequency pressure oscillations were observed. With potential implications for inducer blade loads, these high-frequency components were analyzed extensively in order to understand their origins and impacts to blade loading. Water flow testing provides a technique to determine pump performance without the costs and hazards associated with handling cryogenic propellants. Water has a similar density and Reynolds number to liquid oxygen. In a 70%-scale water flow test, the inducer-only pump performance was evaluated. Over a range of flow rates, the pump inlet pressure was gradually reduced, causing the flow to cavitate near the pump inducer. A nominal, smooth inducer inlet was tested, followed by an inlet duct with a circumferential groove designed to suppress cavitation. A subsequent 52%-scale water flow test in another facility evaluated the combined inducer-impeller pump performance. With the nominal inlet design, the inducer showed traditional cavitation and surge characteristics. Significant bearing loads were created by large side loads on the inducer during synchronous cavitation. The grooved inlet successfully mitigated these loads by greatly reducing synchronous cavitation, however high-frequency pressure oscillations were observed over a range of frequencies. Analytical signal processing techniques showed these oscillations to be created by a rotating, multi-celled train of pressure pulses, and subsequent CFD analysis suggested that such pulses could be created by the interaction of rotating inducer blades with fluid trapped in a cavitation suppression groove. Despite their relatively low amplitude, these high-frequency pressure oscillations posed a design concern due to their sensitivity to flow conditions and

  10. 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

    The modal dynamics of structures with bladed isotropic rotors is analyzed using Hill’s method. First, analytical derivation of the periodic system matrix shows that isotropic rotors with more than two blades can be represented by an exact Fourier series with 3/rev as the highest order. For 2-bladed...... problem is introduced. The corresponding periodic eigenvectors can be used to compute symmetric and anti-symmetric components of the 2-bladed rotor motion, and the additional forward and backward whirling components for rotors with more than two blades. Finally, the generic methods are used on a simple...

  11. The Influence of Cooling Air Injection on Flow Development and Heat Transfer in a Rotating Leading Edge Coolant Duct of a Film-Cooled Turbine Blade

    National Research Council Canada - National Science Library

    Elfert, Martin

    2003-01-01

    .... The improvement of the efficiency demands higher performance from the blade cooling systems with minimized coolant flow rates to cope with the increase in heat load as well as to meet the obligatory safety requirements...

  12. Iterative tuning of feedforward IPC for two-bladed wind turbines

    NARCIS (Netherlands)

    Mulders, S.P.; van Solingen, E.; van Wingerden, J.W.; Beerens, J; Bossanyi, E.; Chaviaropoulos, T.; Cheng, P.W.

    2016-01-01

    At present, the cost of offshore wind energy does not meet the level of onshore wind and fossil-based energy sources. One way to extend the turbine lifetime, and thus reduce cost, is by reduction of the fatigue loads of blades and other turbine parts using Individual Pitch Control (IPC). This type

  13. Materials of large wind turbine blades: Recent results in testing and modeling

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon; Brøndsted, Povl; Nijssen, Rogier

    2012-01-01

    validated. Two methods of structural reliability estimation of the blade, which take into account the stochastic nature of the anisotropic material properties and loads, were developed on the basis of the response surface method and the Edgeworth expansion technique, respectively. The effects of fiber...

  14. Assessment of Interlaminar/Interfiber Failure of UD GRFP for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Leong, Martin Klitgaard; Hvejsel, C.F.; Lund, Erik

    2012-01-01

    A unidirectional glass fiber/epoxy composite material system used for wind turbine blades was characterized under multi-axial loading by cutting specimens in varying off-axis angles relative to the fiber direction. In addition, Iosipescu shear tests were performed on both symmetric and asymmetric...

  15. Interlaminar/interfiber Failure of Unidirectional GFRP used for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Leong, Martin; Hvejsel, C.F.; Lund, Erik

    2013-01-01

    A unidirectional glass fiber/epoxy composite material system used for wind turbine blades was characterized under multi-axial loading by cutting specimens in varying off-axis angles relative to the fiber direction. In addition, Iosipescu shear tests were performed on both symmetric and asymmetric...

  16. Model Predictive Control of Trailing Edge Flaps on a wind turbine blade

    DEFF Research Database (Denmark)

    Castaignet, Damien; Poulsen, Niels Kjølstad; Buhl, Thomas

    2011-01-01

    Trailing Edge Flaps on wind turbine blades have been studied in order to achieve fatigue load reduction on the turbine components. We show in this paper how Model Predictive Control can be used to do frequency weighted control of the trailing edge flaps in order to reduce fatigue damage on the bl...

  17. Structural design optimization of a morphing trailing edge flap for wind turbine blades

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Lin, Yu-Huan; Aagaard Madsen, Helge

    A flap actuation system, the Controllable Rubber Trailing Edge Flap (CRTEF), for distributed load control on a wind turbine blade had been developed in the period from 2006 to 2013 at DTU (http://www.induflap.dk/). The purpose of the presented work is to optimize the structural design of the flex...

  18. 3D flows near a HAWT rotor : A dissection of blade and wake contributions

    NARCIS (Netherlands)

    Micallef, D.

    2012-01-01

    Investigating the flow physics in the vicinity of the wind turbine blade is a challenging endeavour. In the past, focus was placed on the understanding of near wake flows arising from wake vorticity and the rotor loading. In this work, a different approach is taken by considering the flow field in

  19. Conjugate calculation of a film-cooled blade for improvement of the leading edge cooling configuration

    Directory of Open Access Journals (Sweden)

    Norbert Moritz

    2013-03-01

    Full Text Available Great efforts are still put into the design process of advanced film-cooling configurations. In particular, the vanes and blades of turbine front stages have to be cooled extensively for a safe operation. The conjugate calculation technique is used for the three-dimensional thermal load prediction of a film-cooled test blade of a modern gas turbine. Thus, it becomes possible to take into account the interaction of internal flows, external flow, and heat transfer without the prescription of heat transfer coefficients. The focus of the investigation is laid on the leading edge part of the blade. The numerical model consists of all internal flow passages and cooling hole rows at the leading edge. Furthermore, the radial gap flow is also part of the model. The comparison with thermal pyrometer measurements shows that with respect to regions with high thermal load a qualitatively and quantitatively good agreement of the conjugate results and the measurements can be found. In particular, the region in the vicinity of the mid-span section is exposed to a higher thermal load, which requires further improvement of the cooling arrangement. Altogether the achieved results demonstrate that the conjugate calculation technique is applicable for reasonable prediction of three-dimensional thermal load of complex cooling configurations for blades.

  20. Damage tolerance and structural monitoring for wind turbine blades.

    Science.gov (United States)

    McGugan, M; Pereira, G; Sørensen, B F; Toftegaard, H; Branner, K

    2015-02-28

    The paper proposes a methodology for reliable design and maintenance of wind turbine rotor blades using a condition monitoring approach and a damage tolerance index coupling the material and structure. By improving the understanding of material properties that control damage propagation it will be possible to combine damage tolerant structural design, monitoring systems, inspection techniques and modelling to manage the life cycle of the structures. This will allow an efficient operation of the wind turbine in terms of load alleviation, limited maintenance and repair leading to a more effective exploitation of offshore wind. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  1. Damage tolerance and structural monitoring for wind turbine blades

    DEFF Research Database (Denmark)

    McGugan, Malcolm; Pereira, Gilmar Ferreira; Sørensen, Bent F.

    2015-01-01

    The paper proposes a methodology for reliable design and maintenance of wind turbine rotor blades using a condition monitoring approach and a damage tolerance index coupling the material and structure. By improving the understanding of material properties that control damage propagation...... it will be possible to combine damage tolerant structural design, monitoring systems, inspection techniques and modelling to manage the life cycle of the structures. This will allow an efficient operation of the wind turbine in terms of load alleviation, limited maintenance and repair leading to a more effective...... exploitation of offshore wind....

  2. Electro-thermal protection system design against atmospheric frost on turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Noui, M.A.; Perron, J.; Fortin, G. [Quebec Univ., Chicoutimi, PQ (Canada). Anti-Icing Materials International Laboratory

    2010-07-01

    This presentation discussed a research program developed to adapt de-icing thermal heating systems for use in wind turbines. The presence of ice on turbine blades can significantly deteriorate rotor performance. Accumulations of ice can increase the radial load on the turbine blades. The uneven formations of ice can lead to vibrations and the expulsion of pieces of ice into surrounding areas. Ice can also reduce the accuracy of various wind measuring devices. A recent study in Finland showed that turbine heating systems consume 3.6 per cent of annual wind production energy. De-icing systems include protective covers; air inlets; sealing systems; inflation tubes; elastomeric ply; and bond ply. The systems also include blade trailing and loading edges, and blade roots. The energy dissipated by the system's heating element is lost by conduction to the interior of the profile. The research program is now developing a system to improve electrothermal protection against frost that is suitable for turbine blades, as well as a thermal model for simulating its operation in a wind turbine. tabs., figs.

  3. Design Procedure of 4-Bladed Propeller

    African Journals Online (AJOL)

    PROF. O. E. OSUAGWU

    2013-09-01

    Sep 1, 2013 ... ... by converting rotational motion into thrust. A pressure difference is produced between the forward and the rear surfaces of the air foil-shaped blade, and a fluid (such as air or water) is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's principle and. Newton's third law.

  4. 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.

  5. Simulation analysis of turbine blade in 3D printing aquarium

    Directory of Open Access Journals (Sweden)

    Chen Dyi-Cheng

    2017-01-01

    Full Text Available 3D printing of the flexibility is the most admirable place, no matter when or where, as long as the machine can make the abstract design of finished products or difficult to process the finished product printed out as a sample. And in the product design, through the 3D print out the entity, to more specific observation of the advantages and disadvantages of finished products, which shorten the time of many creative research and development, but also relatively reduce the defective factors. As in recent years, 3D printing technology is progressing, material adhesion, precision and parts of the degree of cooperation has increased, coupled with many parts taking into account the cost, production and other issues, and then let a lot of light load small parts or special parts choose to use 3D to print the finished product to replace. This study focuses on the plastic turbine blades that drive water in the aquarium, but the 3D printing is done by stacking. However, the general stress analysis software can set the material to analyze the deformation results of the force, nor the 3D to analyze the software. Therefore, this study first analyzes the deformation of turbine blade by software, and then verifies the situation of 3D printing turbine blade, and then compares the actual results of software analysis and 3D printing. The results can provide the future of 3D product consider the strength factor. The study found that the spiral blade design allows the force points to be dispersed to avoid hard focus.

  6. Metallurgy of gas turbine blades with integral shroud and its influence on blades performance

    International Nuclear Information System (INIS)

    Mazur, Z.; Marino, C.; Kubiak, J.

    1999-01-01

    The influence of the microstructure of the gas turbine blades with integral shroud on the blades performance is presented. The analysis of the solidification process of the gas turbine blades during conventionally casting process (equiaxed grains) with all elements which has influence on the mode of its solidification and variation of the microstructure is carried out. Also, the evaluation of the failure of the gas turbine blade is present. A detailed analysis of the blade tip shroud microstructure (presence of the equiaxed and columnar grains) and its influence on the failure initiation and propagation is carried out. Finally, conclusions and some necessary improvements of the blades casting process to prevent blades failures are presented. (Author) 2 refs

  7. 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.

  8. 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.

  9. 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...... waveforms. The aim of the PSCAD simulations is to study the voltages induced by the lightning current in the blade that may cause internal arcing. With this purpose, the phenomenon of current reflections in the lightning down conductor of the blade and the electromagnetic coupling between the down conductor...... and other internal conductive elements of the blade is studied. Finally, several methods to prevent internal arcing are discussed in order to improve the lightning protection of the blade....

  10. Magnetic nondestructive testing of rotor blade tips

    Science.gov (United States)

    Cardelli, E.; Faba, A.; Marsili, R.; Rossi, G.; Tomassini, R.

    2015-05-01

    This paper deals with a particular magnetic nondestructive technique applied to the control of the position of the steel blades in rotating parts of turbines and engines. The working principle is based on a bridge of four identical magneto-resistive sensors. One sensor is placed near the blades, and the change in magnetic field produced by a permanent magnet and deviated by the change in position of the blade is detected by the sensor bridge. The position of the sensor is indicated, via dedicated FEM simulations, in order to have high sensitivity to the position change and high output signal. The accuracy and effectiveness of the proposed method are shown by experimental tests carried out in our laboratories. In particular, the tests indicate that the proposed magnetic nondestructive technique can be used in an almost large velocity range, and for quite different values of blade tip. The method seems also promising for the detection of blade vibrations.

  11. Jet Engine Bird Ingestion Simulations: Comparison of Rotating to Non-Rotating Fan Blades

    Science.gov (United States)

    Howard, Samuel A.; Hammer, Jeremiah T.; Carney, Kelly S.; Pereira, J. Michael

    2013-01-01

    Bird strike events in commercial airliners are a fairly common occurrence. According to data collected by the US Department of Agriculture, over 80,000 bird strikes were reported in the period 1990 to 2007 in the US alone (Ref. 1). As a result, bird ingestion is an important factor in aero engine design and FAA certification. When it comes to bird impacts on engine fan blades, the FAA requires full-scale bird ingestion tests on an engine running at full speed to pass certification requirements. These rotating tests are complex and very expensive. To reduce development costs associated with new materials for fan blades, it is desirable to develop more cost effective testing procedures than full-scale rotating engine tests for material evaluation. An impact test on a nonrotating single blade that captures most of the salient physics of the rotating test would go a long way towards enabling large numbers of evaluative material screening tests. NASA Glenn Research Center has been working to identify a static blade test procedure that would be effective at reproducing similar results as seen in rotating tests. The current effort compares analytical simulations of a bird strike on various non-rotating blades to a bird strike simulation on a rotating blade as a baseline case. Several different concepts for simulating the rotating loads on a non-rotating blade were analyzed with little success in duplicating the deformation results seen in the rotating case. The rotating blade behaves as if it were stiffer than the non-rotating blade resulting in less plastic deformation from a given bird impact. The key factor limiting the success of the non-rotating blade simulations is thought to be the effect of gyroscopics. Prior to this effort, it was anticipated the difficulty would be in matching the prestress in the blade due to centrifugal forces Additional work is needed to verify this assertion, and to determine if a static test procedure can simulate the gyroscopic effects in

  12. Synthetic jet actuation for load control

    NARCIS (Netherlands)

    de Vries, Hein; van der Weide, Edwin Theodorus Antonius; Hoeijmakers, Hendrik Willem Marie

    2014-01-01

    The reduction of wind turbine blade loads is an important issue in the reduction of the costs of energy production. Reduction of the loads of a non-cyclic nature requires so-called smart rotor control, which involves the application of distributed actuators and sensors to provide fast and local

  13. 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.

  14. Computational Modelling of Materials for Wind Turbine Blades: Selected DTU Wind Energy Activities.

    Science.gov (United States)

    Mikkelsen, Lars Pilgaard; Mishnaevsky, Leon

    2017-11-08

    Computational and analytical studies of degradation of wind turbine blade materials at the macro-, micro-, and nanoscale carried out by the modelling team of the Section Composites and Materials Mechanics, Department of Wind Energy, DTU, are reviewed. Examples of the analysis of the microstructural effects on the strength and fatigue life of composites are shown. Computational studies of degradation mechanisms of wind blade composites under tensile and compressive loading are presented. The effect of hybrid and nanoengineered structures on the performance of the composite was studied in computational experiments as well.

  15. Large Scale Flutter Data for Design of Rotating Blades Using Navier-Stokes Equations

    Science.gov (United States)

    Guruswamy, Guru P.

    2012-01-01

    A procedure to compute flutter boundaries of rotating blades is presented; a) Navier-Stokes equations. b) Frequency domain method compatible with industry practice. Procedure is initially validated: a) Unsteady loads with flapping wing experiment. b) Flutter boundary with fixed wing experiment. Large scale flutter computation is demonstrated for rotating blade: a) Single job submission script. b) Flutter boundary in 24 hour wall clock time with 100 cores. c) Linearly scalable with number of cores. Tested with 1000 cores that produced data in 25 hrs for 10 flutter boundaries. Further wall-clock speed-up is possible by performing parallel computations within each case.

  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. 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)

  18. Airfoil family design for large offshore wind turbine blades

    International Nuclear Information System (INIS)

    Méndez, B; Munduate, X; Miguel, U San

    2014-01-01

    Wind turbine blades size has scaled-up during last years due to wind turbine platform increase especially for offshore applications. The EOLIA project 2007-2010 (Spanish Goverment funded project) was focused on the design of large offshore wind turbines for deep waters. The project was managed by ACCIONA Energia and the wind turbine technology was designed by ACCIONA Windpower. The project included the design of a wind turbine airfoil family especially conceived for large offshore wind turbine blades, in the order of 5MW machine. Large offshore wind turbines suffer high extreme loads due to their size, in addition the lack of noise restrictions allow higher tip speeds. Consequently, the airfoils presented in this work are designed for high Reynolds numbers with the main goal of reducing blade loads and mantainig power production. The new airfoil family was designed in collaboration with CENER (Spanish National Renewable Energy Centre). The airfoil family was designed using a evolutionary algorithm based optimization tool with different objectives, both aerodynamic and structural, coupled with an airfoil geometry generation tool. Force coefficients of the designed airfoil were obtained using the panel code XFOIL in which the boundary layer/inviscid flow coupling is ineracted via surface transpiration model. The desing methodology includes a novel technique to define the objective functions based on normalizing the functions using weight parameters created from data of airfoils used as reference. Four airfoils have been designed, here three of them will be presented, with relative thickness of 18%, 21%, 25%, which have been verified with the in-house CFD code, Wind Multi Block WMB, and later validated with wind tunnel experiments. Some of the objectives for the designed airfoils concern the aerodynamic behavior (high efficiency and lift, high tangential coefficient, insensitivity to rough conditions, etc.), others concern the geometry (good for structural design

  19. 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.

  20. 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.

  1. Measurement of Tip Apex Distance and Migration of Lag Screws and Novel Blade Screw Used for the Fixation of Intertrochanteric Fractures.

    Directory of Open Access Journals (Sweden)

    Jesse Chieh-Szu Yang

    Full Text Available Fixation with a dynamic hip screw (DHS is one of the most common methods for stabilizing intertrochanteric fractures, except for unstable and reverse oblique fracture types. However, failure is often observed in osteoporotic patients whereby the lag screw effectively 'cuts out' through the weak bone. Novel anti-migration blades have been developed to be used in combination with a lag screw ('Blade Screw' to improve the fixation strength in osteoporotic intertrochanteric fractures. An in-vitro biomechanical study and a retrospective clinical study were performed to evaluate lag screw migration when using the novel Blade Screw and a traditional threaded DHS. The biomechanical study showed both the Blade Screw and DHS displayed excessive migration (≥10 mm before reaching 20,000 loading cycles in mild osteoporotic bone, but overall migration of the Blade Screw was significantly less (p ≤ 0.03. Among the patients implanted with a Blade Screw in the clinical study, there was no significant variation in screw migration at 3-months follow-up (P = 0.12. However, the patient's implanted with a DHS did display significantly greater migration (P<0.001 than those implanted with the Blade Screw. In conclusion, the Blade Screw stabilizes the bone fragments during dynamic loading so as to provide significantly greater resistance to screw migration in patients with mild osteoporosis.

  2. Mass balancing of hollow fan blades

    Science.gov (United States)

    Kielb, R. E.

    1986-01-01

    A typical section model is used to analytically investigate the effect of mass balancing as applied to hollow, supersonic fan blades. A procedure to determine the best configuration of an internal balancing mass to provide flutter alleviation is developed. This procedure is applied to a typical supersonic shroudless fan blade which is unstable in both the solid configuration and when it is hollow with no balancing mass. The addition of an optimized balancing mass is shown to stabilize the blade at the design condition.

  3. Investigation of blade performance of horizontal axis wind turbine ...

    African Journals Online (AJOL)

    The shape of rotor blade plays an important role in determining the overall aerodynamic performance of a horizontal axis wind turbine. In this work, blade is designed for a 5KW horizontal axis wind turbine which is already in market. For designing blade, blade element momentum theory (BEMT) is used and a computer ...

  4. Static and Fatigue Analysis of Wind Turbine Blades Subject to Cold Weather Conditions Using Finite Element Analysis

    Science.gov (United States)

    Lillo Gallardo, Patricio Andres

    Canada has aggressive targets for introducing wind energy across the country, but also faces challenges in achieving these goals due to the harsh Canadian climate. One issue which has received little attention in other countries not experiencing these extremes is the behaviour of composite blades in winter conditions. The scope of the work presented is to analyze the static stresses and fatigue response in cold climates using finite element models of the blade. The work opens with a quantification of the extremes of cold experienced in candidate Canadian wind turbine deployment locations. The thesis then narrows its focus to a consideration of the stresses in the root of the composite blades, specifically two common blade-hub connection methods: embedded root carrots and T-bolts. Finite element models of the root are proposed to properly simulate boundary conditions, applied loading and thermal stresses for a 1.5 MW wind turbine. It is shown that the blade root is strongly affected by the thermal stresses caused by the mismatch and orthotrophy of the coefficients of thermal expansion of the blade root constituents. Fatigue analysis of a blade is then presented using temperature dependent material properties including estimated fatigue coefficients.It was found that the natural frequencies of a 1.5 MW wind turbine blade are not significantly altered at cold temperatures. Additionally, cold temperatures slightly increase stresses in the composite blade skin when the blade is loaded, due to an increase in stiffness. Cold temperatures also lead to higher cyclic flapwise bending moments acting on the blade. However, this increase was found not to affect the lifetime fatigue damage. Finally, it was found that the cold climate as seen in Canada improves the fatigue strength of the saturated composite materials used in the blade. The predicted fatigue damage of the triaxial fabric and the spar cap layers in cold climates was therefore predicted to be half that of the

  5. Assessment Report on Innovative Rotor Blades (MAREWINT WP1,D1.3)

    DEFF Research Database (Denmark)

    McGugan, Malcolm; Leble, Vladimir; Pereira, Gilmar Ferreira

    the innovative concept development for wind turbine blades. This covers models and experiments with damage measurement systems embedded within the composite material/structure and numerical methods investigating the effects of leading and trailing edge flaps on modifying the aerodynamic loads on the operating......The offshore wind energy industry faces many challenges in the short to medium term if it is to meet the ambitions of the global community for sustainable energy supply in the future. Not least among these challenges is the issue of rotor blades. Innovative design for “smart” rotor blades...... with embedded sensors and actuation are being developed that will deliver an improved whole-life performance, and a structural health management based operational concept. In this report, the work of two early stage researchers within the Initial Training Network MAREWINT is presented that support...

  6. Fatigue fracture of cutter blade made of high-speed steel

    Directory of Open Access Journals (Sweden)

    Beata Letkowska

    2015-04-01

    Full Text Available The quality of the surface of cyclically loaded components is very important. Many observations confirm that the root cause of the micro cracks (causing the fatigue fracture are primarily a surface's defects appearing during production process. These surface defects can be also caused by engraving processes used to perform identification marks. This paper presents the failure analysis of broken blade of the cutter Ku 500VX. The blade was subject of standard metallographic examination, hardness measurements, fractography analysis and metallographic studies using stereoscopic, light and scanning electron microscopes. The damage of the blade was caused by changes of the structure (formation of the brittle micro dendritic structure that occurred during manual electric engraving process when the material was heated till its melting point. As a result the stresses occurred in surface what provided to micro cracking and to propagate the fatigue fracture. The origin of this fatigue fracture was in the place where the inscription was made.

  7. Mass detection, localization and estimation for wind turbine blades based on statistical pattern recognition

    DEFF Research Database (Denmark)

    Colone, L.; Hovgaard, K.; Glavind, Lars

    2018-01-01

    A method for mass change detection on wind turbine blades using natural frequencies is presented. The approach is based on two statistical tests. The first test decides if there is a significant mass change and the second test is a statistical group classification based on Linear Discriminant...... Analysis. The frequencies are identified by means of Operational Modal Analysis using natural excitation. Based on the assumption of Gaussianity of the frequencies, a multi-class statistical model is developed by combining finite element model sensitivities in 10 classes of change location on the blade......, the smallest area being 1/5 of the span. The method is experimentally validated for a full scale wind turbine blade in a test setup and loaded by natural wind. Mass change from natural causes was imitated with sand bags and the algorithm was observed to perform well with an experimental detection rate of 1...

  8. 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

  9. A smart rotor configuration with linear quadratic control of adaptive trailing edge flaps for active load alleviation

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Poulsen, Niels Kjølstad

    2015-01-01

    The paper proposes a smart rotor configuration where adaptive trailing edge flaps (ATEFs) are employed for active alleviation of the aerodynamic loads on the blades of the NREL 5 MW reference turbine. The flaps extend for 20% of the blade length and are controlled by a linear quadratic (LQ...... signals described by simple functions of the blade azimuthal position are included in the identification to avoid biases from the periodic load variations observed on a rotating blade. The LQ controller uses the same periodic disturbance signals to handle anticipation of the loads periodic component...

  10. Pin and roller attachment system for ceramic blades

    Science.gov (United States)

    Shaffer, J.E.

    1995-07-25

    In a turbine, a plurality of blades are attached to a turbine wheel by way of a plurality of joints which form a rolling contact between the blades and the turbine wheel. Each joint includes a pin and a pair of rollers to provide rolling contact between the pin and an adjacent pair of blades. Because of this rolling contact, high stress scuffing between the blades and the turbine wheel reduced, thereby inhibiting catastrophic failure of the blade joints. 3 figs.

  11. Blade Vibration Measurement System for Unducted Fans

    Science.gov (United States)

    Marscher, William

    2014-01-01

    With propulsion research programs focused on new levels of efficiency and noise reduction, two avenues for advanced gas turbine technology are emerging: the geared turbofan and ultrahigh bypass ratio fan engines. Both of these candidates are being pursued as collaborative research projects between NASA and the engine manufacturers. The high bypass concept from GE Aviation is an unducted fan that features a bypass ratio of over 30 along with the accompanying benefits in fuel efficiency. This project improved the test and measurement capabilities of the unducted fan blade dynamic response. In the course of this project, Mechanical Solutions, Inc. (MSI) collaborated with GE Aviation to (1) define the requirements for fan blade measurements; (2) leverage MSI's radar-based system for compressor and turbine blade monitoring; and (3) develop, validate, and deliver a noncontacting blade vibration measurement system for unducted fans.

  12. 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

  13. Aircraft rotor blade with passive tuned tab

    Science.gov (United States)

    Campbell, T. G. (Inventor)

    1985-01-01

    A structure for reducing vibratory airloading in a rotor blade with a leading edge and a trailing edge includes a cut out portion at the trailing edge. A substantially wedge shaped cross section, inertially deflectable tab, also with a leading edge and a trailing edge is pivotally mounted in the cut out portion. The trailing edge of the tab may move above and below the rotor blade. A torsion strap applies force against the tab when the trailing edge of the tab is above and below the rotor blade. A restraining member is slidably movable along the torsion strap to vary torsional biasing force supplied by the torsion bar to the tab. A plurality of movable weights positioned between plates vary a center of gravity of the tab. Skin of the tab is formed from unidirectional graphite and fiberglass layers. Sliders coupled with a pinned degree of freedom at rod eliminate bending of tab under edgewise blade deflection.

  14. Adhesive Joints in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Jørgensen, Jeppe Bjørn

    The industrial goal of this PhD project is to enable manufacturing of larger wind turbine blades by improving the existing design methods for adhesive joints. This should improve the present joint design such that more efficient wind turbine blades can be produced. The main scientific goal...... of the project is to develop new- and to improve the existing design rules for adhesive joints in wind turbine blades. The first scientific studies of adhesive joints were based on stress analysis, which requires that the bond-line is free of defects, but this is rarely the case for a wind turbine blade. Instead...... curing and test temperatures) on the formation of transverse cracks in the adhesive were tested experimentally. It was assumed that the transverse cracks evolved due to a combination of mechanical- and residual stresses in the adhesive. A new approach was developed that allows the residual stress...

  15. Shape Optimization of Wind Turbine Blades

    DEFF Research Database (Denmark)

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

    2009-01-01

    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......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...... 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...

  16. 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.

  17. Review of the Phenomenon of Ice Shedding from Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    H Xue

    2016-08-01

    Full Text Available Wind power is a sustainable source of energy. However, there are certain challenges to be  overcome. One of the operational challenges is the phenomenon of ice shedding. Icing happens on wind turbine blades in cold regions. When ice grows to a certain size, it separates from the wind turbine blades resulting in the phenomenon of ice shedding. This phenomenon is of significantly dangerous for equipment and personnel in the region. Ice shedding may happen either because of vibrations or bending in blades. However, it was noticed by operators at Nygårdsfjell wind park, Narvik, Norway that ice shedding is more probable to happen when blades are stopped and turned back on. This observation reveals the fact that bending of blades (from loaded to unloaded positions allows the ice to separate and hence result in ice shedding. This can be linked to the phenomenon of icing, mechanical and adhesive properties of ice. This paper reviews above in detail.

  18. OPTIMIZING THE SHAPE OF ROTOR BLADES FOR MAXIMUM POWER EXTRACTION IN MARINE CURRENT TURBINES

    Directory of Open Access Journals (Sweden)

    J.A. Esfahani

    2012-12-01

    Full Text Available In this paper the shape of rotor blades in Marine Current Turbines (MCTs are investigated. The evaluation of hydrodynamic loads on blades is performed based on the Blade Element Momentum (BEM theory. The shape of blades is optimized according to the main parameters in the configuration and operation of these devices. The optimization is conducted based on the ability of the blades to harness the maximum energy during operating. The main parameters investigated are the tip speed ratio and angle of attack. Furthermore, the influence of these parameters on the maximum energy extraction from fluid flow over a hydrofoil is evaluated. It is shown that the effect of the angle of attack on power extraction is greater than that of the tip speed ratio, while both are found to be significant. Additionally, the proper angle of attack is the angle at which the lift to drag ratio is at its maximum value. However, if a proper angle of attack is chosen, the variations in power coefficient would not be effectively changed with small variations in the tip speed ratio.

  19. Analysis of Stainless Steel Sandwich Panels with a Metal Foam Care for Lightweight Fan Blade Design

    Science.gov (United States)

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

    2004-01-01

    The quest for cheap, low density and high performance materials in the design of aircraft and rotorcraft engine fan and propeller blades poses immense challenges to the materials and structural design engineers. Traditionally, these components have been fabricated using expensive materials such as light weight titanium alloys, polymeric composite materials and carbon-carbon composites. The present study investigates the use of P sandwich foam fan blade made up of solid face sheets and a metal foam core. The face sheets and the metal foam core material were an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. The stiffness of the sandwich structure is increased by separating the two face sheets by a foam core. The resulting structure possesses a high stiffness while being lighter than a similar solid construction. Since the face sheets carry the applied bending loads, the sandwich architecture is a viable engineering concept. The material properties of 17-4 PH metal foam are reviewed briefly to describe the characteristics of the sandwich structure for a fan blade application. A vibration analysis for natural frequencies and P detailed stress analysis on the 17-4 PH sandwich foam blade design for different combinations of skin thickness and core volume %re presented with a comparison to a solid titanium blade.

  20. Low-pressure reversible axial fan with straight profile blades and relatively high efficiency

    Directory of Open Access Journals (Sweden)

    Spasić Živan T.

    2012-01-01

    Full Text Available The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.

  1. Effects of rotor location, coning, and tilt on critical loads in large wind turbines

    Science.gov (United States)

    Spera, D. A.; Janetzke, D. C.

    1978-01-01

    Several large (1500 kW) horizontal rotor configurations were analyzed to determine the effects on dynamic loads of upwind downwind rotor locations, coned and radial blade positions, and tilted and horizontal rotor axis positions. Loads were calculated for a range of wind velocities at three locations in the structure: (1) the blade shank; (2) the hub shaft; and (3) the yaw drive. Blade axis coning and rotor axis tilt were found to have minor effects on loads. However, locating the rotor upwind of the tower significantly reduced loads at all locations analyzed.

  2. Rotor blade construction for circulation control aircraft

    Science.gov (United States)

    Carter, Sr., Donald R. (Inventor); Krauss, Timothy A. (Inventor); Sedlak, Matthew (Inventor)

    1986-01-01

    A circulation control aircraft rotor blade having a spanwise Coanda surface 16 and a plurality of spanwise extending flexible composite material panels 18 cooperating with the surface to define slots for the discharge of compressed air from within the blade with each panel having first flexure means 60 associated with screw adjustments 36 for establishing a slot opening preload and second flexure means 62 associated with screw adjustments 38 for establishing a slot maximum opening.

  3. 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

  4. 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.

  5. Super titanium blades for advanced steam turbines

    International Nuclear Information System (INIS)

    Coulon, P.A.

    1990-01-01

    In 1986, the Alsthom Steam Turbines Department launched the manufacture of large titanium alloy blades: airfoil length of 1360 mm and overall length of 1520 mm. These blades are designed for the last-stage low pressure blading of advanced steam turbines operating at full speed (3000 rpm) and rating between 300 and 800 MW. Using titanium alloys for steam turbine exhaust stages as substitutes for chrome steels, due to their high strength/density ratio and their almost complete resistance to corrosion, makes it possible to increase the length of blades significantly and correspondingly that steam passage section (by up to 50%) with a still conservative stresses level in the rotor. Alsthom relies on 8 years of experience in the field of titanium, since as early as 1979 large titanium blades (airfoil length of 1240 mm, overall length of 1430 mm) were erected for experimental purposes on the last stage of a 900 MW unit of the Dampierre-sur-Loire power plant and now totals 45,000 operating hours without problems. The paper summarizes the main properties (chemical, mechanical and structural) recorded on very large blades and is based in particular on numerous fatigue corrosion test results to justify the use of the Ti 6 Al 4 V alloy in a specific context of micrographic structure

  6. Advanced Composite Wind Turbine Blade Design Based on Durability and Damage Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Abumeri, Galib [AlphaSTAR Corporation, Long Beach, CA (United States); Abdi, Frank [AlphaSTAR Corporation, Long Beach, CA (United States)

    2012-02-16

    The objective of the program was to demonstrate and verify Certification-by-Analysis (CBA) capability for wind turbine blades made from advanced lightweight composite materials. The approach integrated durability and damage tolerance analysis with robust design and virtual testing capabilities to deliver superior, durable, low weight, low cost, long life, and reliable wind blade design. The GENOA durability and life prediction software suite was be used as the primary simulation tool. First, a micromechanics-based computational approach was used to assess the durability of composite laminates with ply drop features commonly used in wind turbine applications. Ply drops occur in composite joints and closures of wind turbine blades to reduce skin thicknesses along the blade span. They increase localized stress concentration, which may cause premature delamination failure in composite and reduced fatigue service life. Durability and damage tolerance (D&DT) were evaluated utilizing a multi-scale micro-macro progressive failure analysis (PFA) technique. PFA is finite element based and is capable of detecting all stages of material damage including initiation and propagation of delamination. It assesses multiple failure criteria and includes the effects of manufacturing anomalies (i.e., void, fiber waviness). Two different approaches have been used within PFA. The first approach is Virtual Crack Closure Technique (VCCT) PFA while the second one is strength-based. Constituent stiffness and strength properties for glass and carbon based material systems were reverse engineered for use in D&DT evaluation of coupons with ply drops under static loading. Lamina and laminate properties calculated using manufacturing and composite architecture details matched closely published test data. Similarly, resin properties were determined for fatigue life calculation. The simulation not only reproduced static strength and fatigue life as observed in the test, it also showed composite

  7. Optimization of Root Section for Ultra-long Steam Turbine Rotor Blade

    Science.gov (United States)

    Hála, Jindřich; Luxa, Martin; Šimurda, David; Bobčík, Marek; Novák, Ondřej; Rudas, Bartoloměj; Synáč, Jaroslav

    2018-04-01

    This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Mach number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements (optical and pneumatic).

  8. Method of calculating blade-to-blade plane flow in centrifugal pump

    Science.gov (United States)

    Jackson, E. D.

    1970-01-01

    Steam filament solution determines velocity distribution due to potential flow in the blade-to-blade plane of the radial impeller. This is used to determine the mass-averaged relative fluid angle, which is in turn used in an axisymmetric program to obtain steam surfaces of the assumed axisymmetric flow.

  9. The influence on energy conversion and induction from large blade deflections

    Energy Technology Data Exchange (ETDEWEB)

    Aagaard Madsen, H.; Rasmussen, F. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    Flexible blades or coning means that the swept area is no longer a plane disc as assumed in the blade element momentum (BEM) theory. How is the induced flow field of the rotor influenced by such changes and what does this mean for the loading and energy conversion? This has been investigated by studying the flow through four different rotor geometries on basis of a numerical, axis-symmetric actuator disc model. Volume forces perpendicular to the local blade surface were applied and the converted power is the work performed by these forces. To simplify the comparisons, only a constant load distribution was used. The numerical results show that the shape of the rotor disc has considerable influence on the induction or axial velocity. The axial velocities vary with radial position in the case of constant loading where BEM theory gives constant velocities. There is considerable variation of the local power coefficient C{sub p,loc} even for constant loading. Locally, C{sub p,loc} can exceed the Betz limit. However, integrating C{sub p,loc} over the rotor plane, the total power coefficient for the different rotors are exactly the same. (au)

  10. Analysis of SNL/MSU/DOE fatigue database trends for wind turbine blade materials.

    Energy Technology Data Exchange (ETDEWEB)

    Mandell, John F. (Montana State University, Bozeman, MT); Ashwill, Thomas D.; Wilson, Timothy J. (Montana State University, Bozeman, MT); Sears, Aaron T. (Montana State University, Bozeman, MT); Agastra, Pancasatya (Montana State University, Bozeman, MT); Laird, Daniel L.; Samborsky, Daniel D. (Montana State University, Bozeman, MT)

    2010-12-01

    This report presents an analysis of trends in fatigue results from the Montana State University program on the fatigue of composite materials for wind turbine blades for the period 2005-2009. Test data can be found in the SNL/MSU/DOE Fatigue of Composite Materials Database which is updated annually. This is the fifth report in this series, which summarizes progress of the overall program since its inception in 1989. The primary thrust of this program has been research and testing of a broad range of structural laminate materials of interest to blade structures. The report is focused on current types of infused and prepreg blade materials, either processed in-house or by industry partners. Trends in static and fatigue performance are analyzed for a range of materials, geometries and loading conditions. Materials include: sixteen resins of three general types, five epoxy based paste adhesives, fifteen reinforcing fabrics including three fiber types, three prepregs, many laminate lay-ups and process variations. Significant differences in static and fatigue performance and delamination resistance are quantified for particular materials and process conditions. When blades do fail, the likely cause is fatigue in the structural detail areas or at major flaws. The program is focused strongly on these issues in addition to standard laminates. Structural detail tests allow evaluation of various blade materials options in the context of more realistic representations of blade structure than do the standard test methods. Types of structural details addressed in this report include ply drops used in thickness tapering, and adhesive joints, each tested over a range of fatigue loading conditions. Ply drop studies were in two areas: (1) a combined experimental and finite element study of basic ply drop delamination parameters for glass and carbon prepreg laminates, and (2) the development of a complex structured resin-infused coupon including ply drops, for comparison studies of

  11. 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)

  12. Spacer grid with mixing blades for nuclear fuel assembly

    International Nuclear Information System (INIS)

    Noailly, J.

    1986-01-01

    The spacer grid for nuclear fuel assembly has two sets of intersecting metal plates provided with blades and defining cells. The plates are fitted only with half-blades associated with a single grid opening. The half-blades of adjacent cells are arranged at 90deg C to each other and each plate has at most one half-blade at each corner of a cell. The invention concerns fuel assemblies of pressurized water reactors. The blades arranged on a single side of the plate provide a good hydraulic uniformity. The invention provides a uniform distribution of blades (and thus of absorbing material in each hydraulic cell) [fr

  13. Axial compressor blade design for desensitization of aerodynamic performance and stability to tip clearance

    Science.gov (United States)

    Erler, Engin

    Tip clearance flow is the flow through the clearance between the rotor blade tip and the shroud of a turbomachine, such as compressors and turbines. This flow is driven by the pressure difference across the blade (aerodynamic loading) in the tip region and is a major source of loss in performance and aerodynamic stability in axial compressors of modern aircraft engines. An increase in tip clearance, either temporary due to differential radial expansion between the blade and the shroud during transient operation or permanent due to engine wear or manufacturing tolerances on small blades, increases tip clearance flow and results in higher fuel consumption and higher risk of engine surge. A compressor design that can reduce the sensitivity of its performance and aerodynamic stability to tip clearance increase would have a major impact on short and long-term engine performance and operating envelope. While much research has been carried out on improving nominal compressor performance, little had been done on desensitization to tip clearance increase beyond isolated observations that certain blade designs such as forward chordwise sweep, seem to be less sensitive to tip clearance size increase. The current project aims to identify through a computational study the flow features and associated mechanisms that reduces sensitivity of axial compressor rotors to tip clearance size and propose blade design strategies that can exploit these results. The methodology starts with the design of a reference conventional axial compressor rotor followed by a parametric study with variations of this reference design through modification of the camber line and of the stacking line of blade profiles along the span. It is noted that a simple desensitization method would be to reduce the aerodynamic loading of the blade tip which would reduce the tip clearance flow and its proportional contribution to performance loss. However, with the larger part of the work on the flow done in this

  14. Remote Monitoring of the Structural Health of Hydrokinetic Composite Turbine Blades

    Energy Technology Data Exchange (ETDEWEB)

    J.L. Rovey

    2012-09-21

    A health monitoring approach is investigated for hydrokinetic turbine blade applications. In-service monitoring is critical due to the difficult environment for blade inspection and the cost of inspection downtime. Composite blade designs have advantages that include long life in marine environments and great control over mechanical properties. Experimental strain characteristics are determined for static loads and free-vibration loads. These experiments are designed to simulate the dynamic characteristics of hydrokinetic turbine blades. Carbon/epoxy symmetric composite laminates are manufactured using an autoclave process. Four-layer composite beams, eight-layer composite beams, and two-dimensional eight-layer composite blades are instrumented for strain. Experimental results for strain measurements from electrical resistance gages are validated with theoretical characteristics obtained from in-house finite-element analysis for all sample cases. These preliminary tests on the composite samples show good correlation between experimental and finite-element strain results. A health monitoring system is proposed in which damage to a composite structure, e.g. delamination and fiber breakage, causes changes in the strain signature behavior. The system is based on embedded strain sensors and embedded motes in which strain information is demodulated for wireless transmission. In-service monitoring is critical due to the difficult environment for blade inspection and the cost of inspection downtime. Composite blade designs provide a medium for embedding sensors into the blades for in-situ health monitoring. The major challenge with in-situ health monitoring is transmission of sensor signals from the remote rotating reference frame of the blade to the system monitoring station. In the presented work, a novel system for relaying in-situ blade health measurements in hydrokinetic systems is described and demonstrated. An ultrasonic communication system is used to transmit

  15. 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.

  16. 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.

  17. 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.

  18. 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. © 2015 American Academy of Forensic Sciences.

  19. 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).

  20. A Model Based Control methodology combining Blade Pitch and Adaptive Trailing Edge Flaps in a common framework

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Bergami, Leonardo; Andersen, Peter Bjørn

    2013-01-01

    This work investigates how adaptive trailing edge flaps and classical blade pitch can work in concert using a model-based state space control formulation. The trade-off between load reduction and actuator activity is decided by setting different weights in the objective function used by the model...

  1. A Model Based Control methodology combining Blade Pitch and Adaptive Trailing Edge Flaps in a common framework

    DEFF Research Database (Denmark)

    This work investigates how adaptive trailing edge flaps and classical blade pitch can work in concert using a model-based state space control formulation. The trade-off between load reduction and actuator activity is decided by setting different weights in the objective function used by the model...

  2. Study of controlled diffusion stator blading. 1. Aerodynamic and mechanical design report

    Science.gov (United States)

    Canal, E.; Chisholm, B. C.; Lee, D.; Spear, D. A.

    1981-01-01

    Pratt & Whitney Aircraft is conducting a test program for NASA in order to demonstrate that a controlled-diffusion stator provides low losses at high loadings and Mach numbers. The technology has shown great promise in wind tunnel tests. Details of the design of the controlled diffusion stator vanes and the multiple-circular-arc rotor blades are presented. The stage, including stator and rotor, was designed to be suitable for the first-stage of an advanced multistage, high-pressure compressor.

  3. Complementary Aerodynamic Performance Datasets for Variable Speed Power Turbine Blade Section from Two Independent Transonic Turbine Cascades

    Science.gov (United States)

    Flegel, Ashlie B.; Welch, Gerard E.; Giel, Paul W.; Ames, Forrest E.; Long, Jonathon A.

    2015-01-01

    Two independent experimental studies were conducted in linear cascades on a scaled, two-dimensional mid-span section of a representative Variable Speed Power Turbine (VSPT) blade. The purpose of these studies was to assess the aerodynamic performance of the VSPT blade over large Reynolds number and incidence angle ranges. The influence of inlet turbulence intensity was also investigated. The tests were carried out in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility and at the University of North Dakota (UND) High Speed Compressible Flow Wind Tunnel Facility. A large database was developed by acquiring total pressure and exit angle surveys and blade loading data for ten incidence angles ranging from +15.8deg to -51.0deg. Data were acquired over six flow conditions with exit isentropic Reynolds number ranging from 0.05×106 to 2.12×106 and at exit Mach numbers of 0.72 (design) and 0.35. Flow conditions were examined within the respective facility constraints. The survey data were integrated to determine average exit total-pressure and flow angle. UND also acquired blade surface heat transfer data at two flow conditions across the entire incidence angle range aimed at quantifying transitional flow behavior on the blade. Comparisons of the aerodynamic datasets were made for three "match point" conditions. The blade loading data at the match point conditions show good agreement between the facilities. This report shows comparisons of other data and highlights the unique contributions of the two facilities. The datasets are being used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range.

  4. 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.

  5. Magnus wind turbines as an alternative to the blade ones

    International Nuclear Information System (INIS)

    Bychkov, N M; Dovgal, A V; Kozlov, V V

    2007-01-01

    Experimental and calculated data on a wind turbine equipped with rotating cylinders instead of traditional blades are reported. Optimal parameters and the corresponding operational characteristics of the windwheel are given in comparison with those of the blade wind turbines

  6. 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)

  7. 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.

  8. Ion beam analysis of gas turbine blades: evaluation of refurbishment ...

    Indian Academy of Sciences (India)

    . To evaluate the refurbishment quality of used gas turbine blades, scanning proton microscopy was employed to study the cross-sections of four samples of turbine blades denoted ... explain this conflict, one should note that matrix composi-.

  9. Structural integrity of wind tunnel wooden fan blades

    Science.gov (United States)

    Young, Clarence P., Jr.; Wingate, Robert T.; Rooker, James R.; Mort, Kenneth W.; Zager, Harold E.

    1991-01-01

    Information is presented which was compiled by the NASA Inter-Center Committee on Structural Integrity of Wooden Fan Blades and is intended for use as a guide in design, fabrication, evaluation, and assurance of fan systems using wooden blades. A risk assessment approach for existing NASA wind tunnels with wooden fan blades is provided. Also, state of the art information is provided for wooden fan blade design, drive system considerations, inspection and monitoring methods, and fan blade repair. Proposed research and development activities are discussed, and recommendations are provided which are aimed at future wooden fan blade design activities and safely maintaining existing NASA wind tunnel fan blades. Information is presented that will be of value to wooden fan blade designers, fabricators, inspectors, and wind tunnel operations personnel.

  10. Design and fabrication of a wind turbine blade | Laryea | Ghana ...

    African Journals Online (AJOL)

    Institute of Industrial Research, Accra. Earlier turbine blades were manufactured from seasoned wood. The designed blade reported in the study was fabricated from fiberglass and epoxy resin compositions using wood for the mould pattern.

  11. New airfoil sections for straight bladed turbine

    International Nuclear Information System (INIS)

    Boumaza, B.

    1987-07-01

    A theoretical investigation of aerodynamic performance for vertical axis Darrieus wind turbine with new airfoils sections is carried out. The blade section aerodynamics characteristics are determined from turbomachines cascade model. The model is also adapted to the vertical Darrieus turbine for the performance prediction of the machine. In order to choose appropriate value of zero-lift-drag coefficient in calculation, an analytical expression is introduced as function of chord-radius ratio and Reynolds numbers. New airfoils sections are proposed and analyzed for straight-bladed turbine

  12. Designing for hot-blade cutting

    DEFF Research Database (Denmark)

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

    2016-01-01

    by authors of the paper, which facilitates high-speed production of doubly-curved foam moulds. Complementary to design rationalisation, in which arbitrary surfaces are translated to hot-blade-cuttable geometries, the presented method enables architects and designers to design directly with the non......-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...

  13. 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...

  14. Individual Blade Control of a 5-bladed Rotor Using the Multiple Swashplate System

    OpenAIRE

    Küfmann, Philip; Bartels, Rainer; van der Wall, Berend G.; Schneider, Oliver; Holthusen, Hermann; Postma, Jos

    2017-01-01

    After its first wind tunnel test in 2015, the multiple swashplate system (META) as well as the DLR's rotor test rig were modified and upgraded extensively to allow IBC operation on a five-bladed rotor system. In late 2016 a second wind tunnel test was performed on a Mach-scaled, five-bladed model rotor with the goal to reduce Vibration, noise and required rotor power on a five-bladed rotor in different flight conditions using proven IBC strategies. Highlights of the test matrix were 2/rev swe...

  15. A comparison study of the two-bladed partial pitch turbine during normal operation and an extreme gust conditions

    DEFF Research Database (Denmark)

    Kim, Taeseong; Pedersen, Mads Mølgaard; Larsen, Torben J.

    2014-01-01

    This paper shows the load comparisons between the numerical simulation and the full-scale load measurement data. First part of this paper includes the comparisons of statistic load in terms of maximum, mean, and minimum values for the selected normal operation cases. The blade root bending moments...... and tower top bending moments are compared. Second part of this paper introduces the dynamic response comparisons during an extreme wind gust condition where the wind speed changed approximately 10 m/s during three seconds. The rotor speed and blade root flapwise and edgewise bending moment are compared....... The nonlinear aeroelastic simulation code HAWC2 is used for the simulations. A very fine agreement between the simulated and the full-scale measured loads is seen for the both comparisons....

  16. Active aerodynamic load control on wind turbines : Aeroservoelastic modeling and wind tunnel

    NARCIS (Netherlands)

    Barlas, A.

    2011-01-01

    This thesis investigates particular concepts and technologies that can alleviate fatigue loads on wind turbines by using distributed active aerodynamic devices on the blades, a concept briefly referred to as `smart blades'. Firstly, published research work on smart control devices is reviewed, and

  17. Impact of Higher Fidelity Models on Simulation of Active Aerodynamic Load Control For Fatigue Damage Reduction

    NARCIS (Netherlands)

    Resor, B.; Wilson, D.; Berg, D.; Berg, J.; Barlas, T.; Van Wingerden, J.W.; Van Kuik, G.A.M.

    2010-01-01

    Active aerodynamic load control of wind turbine blades is being investigated by the wind energy research community and shows great promise, especially for reduction of turbine fatigue damage in blades and nearby components. For much of this work, full system aeroelastic codes have been used to

  18. Investigation of the theoretical load alleviation potential using trailing edge flaps controlled by inflow data

    DEFF Research Database (Denmark)

    Fischer, Andreas; Aagaard Madsen, Helge

    2016-01-01

    A novel control concept for fatigue load reduction with trailing edge flaps based on the measurement of the inflow locally on the blade was presented. The investigation was conducted with the aeroelastic code HAWC2. The aerodynamic modelling in the code is based on blade element momentum theory...... effects seem to be negligible. Copyright © 2015 John Wiley & Sons, Ltd....

  19. 76 FR 25648 - Special Conditions: Gulfstream Model GVI Airplane; Limit Engine Torque Loads for Sudden Engine...

    Science.gov (United States)

    2011-05-05

    ... any fan, compressor, or turbine blade, the proposed standard would require engine mounts and... dynamic loads resulting from: (a) The loss of any fan, compressor, or turbine blade; and (b) Separately... are designed with large bypass fans. In the event of a structural failure, these engines are capable...

  20. Design and test of box girder for a large wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Per H.; Tesauro, A.; Bitsche, R. [Technical Univ. of Denmark. DTU Wind Energy, DTU Risoe Campus, Roskilde (Denmark)] [and others

    2012-09-15

    This report is covering the structural design and full scale test of a box girder as a part of the project ''Demonstration of new blade design using manufacturing process simulations'' supported by the EUDP program. A box girder with a predetermined outer geometry was designed using new inventions, which create an inner structure in the box girder. With a combination of advanced FEM analysis and the inventions it was possible to reduce the material thickness of the cap by up to 40%. The new design of the box girder was manufactured at SSP Technology A/S, where it was demonstrated that the manufacturing process could include the new inventions. Subsequently the box girder was transported to the blade test facility at DTU Wind Energy. A series of test was performed with the blade to investigate the behaviour during loading, and finally the girder was loaded to ultimate failure. The report includes the description of the test setup, the test and an overview over the results from the test performed on the box girder. During the final test the box girder failed at 58 % of the expected ultimate load. Unfortunately, no definite conclusion could be made concerning the failure mechanism. (Author)

  1. Four-Point Bending Strength Testing of Pultruded Fiberglass Composite Wind Turbine Blade Sections

    Energy Technology Data Exchange (ETDEWEB)

    Musial, W.; Bourne, B; Hughes, S; Zuteck, M. D. (MDZ Consulting)

    2001-07-10

    The ultimate strength of the PS Enterprises pultruded blade section was experimentally determined under four-point bending at the National Renewable Energy Laboratory. Thirteen 8-foot long full-scale blade segments were individually tested to determine their maximum moment carrying capability. Three airfoil-bending configurations were tested: high- and low-pressure skin buckling, and low pressure skin buckling with foam interior reinforcement. Maximum strain was recorded for each sample on the compressive and tensile surfaces of each test blade. Test data are compared to the results of three analytical buckling prediction methods. Based on deviations from the linear strain versus load curve, data indicate a post-buckling region. High-pressure side buckling occurred sooner than low-pressure side buckling. The buckling analyses were conservative for both configurations, but high-pressure side buckling in particular was substantially under-predicted. Both high- and low-pressure buckling configurations had very similar failure loads. These results suggests that a redundant load path may be providing strength to the section in the post-buckling region, making the onset of panel buckling a poor predictor of ultimate strength for the PS Enterprises pultrusion.

  2. 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...... of the rotor, icing and lightning. Research is done throughout the world in order to develop and improve such measurement systems. Commercial hardware and software available for the described purpose is presented in the report....

  3. Method to predict fatigue lifetimes of GRP wind turbine blades and comparison with experiments

    Energy Technology Data Exchange (ETDEWEB)

    Echtermeyer, A.T. [Det Norske Veritas Research AS, Hoevik (Norway); Kensche, C. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Stuttgart (Germany, F.R); Bach, P. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Poppen, M. [Aeronautical Research Inst. of Sweden, Bromma (Sweden); Lilholt, H.; Andersen, S.I.; Broendsted, P. [Risoe National Lab., Roskilde (Denmark)

    1996-12-01

    This paper describes a method to predict fatigue lifetimes of fiber reinforced plastics in wind turbine blades. It is based on extensive testing within the EU-Joule program. The method takes the measured fatigue properties of a material into account so that credit can be given to materials with improved fatigue properties. The large number of test results should also give confidence in the fatigue calculation method for fiber reinforced plastics. The method uses the Palmgren-Miner sum to predict lifetimes and is verified by tests using well defined load sequences. Even though this approach is generally well known in fatigue analysis, many details in the interpretation and extrapolation of the measurements need to be clearly defined, since they can influence the results considerably. The following subjects will be described: Method to measure SN curves and to obtain tolerance bounds, development of a constant lifetime diagram, evaluation of the load sequence, use of Palmgren-Miner sum, requirements for load sequence testing. The fatigue lifetime calculation method has been compared against measured data for simple loading sequences and the more complex WISPERX loading sequence for blade roots. The comparison is based on predicted mean lifetimes, using the same materials to obtain the basic SN curves and to measure laminates under complicated loading sequences. 24 refs, 7 figs, 5 tabs

  4. A deflection monitoring system for a wind turbine blade

    DEFF Research Database (Denmark)

    2017-01-01

    A wind turbine blade comprising a system for monitoring the deflection of a wind turbine blade is described. The system comprises a wireless range-measurement system, having at least one wireless communication device located towards the root end of the blade and at least one wireless communication...

  5. Channel flow analysis. [velocity distribution throughout blade flow field

    Science.gov (United States)

    Katsanis, T.

    1973-01-01

    The design of a proper blade profile requires calculation of the blade row flow field in order to determine the velocities on the blade surfaces. An analysis theory is presented for several methods used for this calculation and associated computer programs that were developed are discussed.

  6. 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 ...

  7. 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...

  8. Analysis of horizontal axis wind turbine blade using CFD | Nigam ...

    African Journals Online (AJOL)

    Blade is very essential part of HAWT (horizontal axis wind turbine). Forces for Lift and drag on the blade has an important role in the wind turbine performance. The main purpose of this work is to perform CFD analysis of a blade and airfoil of wind turbine using k-ω SST model. In this present study NACA 634 -221 airfoil ...

  9. Manufacture of Power Hacksaw Blades From Locally Available ...

    African Journals Online (AJOL)

    The manufacture of power hacksaw blades using worn out sawmill blades made of medium carbon steel has bean achieved. They were produced through carburization, hardening and tempering processes. The produced power hacksaw blade when compared with the imported one showed the former having a slightly ...

  10. Genetic control of leaf-blade morphogenesis by the INSECATUS ...

    Indian Academy of Sciences (India)

    2010-08-03

    Aug 3, 2010 ... domain bears compound pinna blades of tendrilled leaflets in mfp leaf blades. The interactions among uni-tac, af, tl and mfp mutations have revealed the functional roles of the four genes in leaf-blade morphogenesis (Marx 1987; Hofer and Ellis 1998; Gourlay et al. 2000; DeMason 2005; Mishra et al. 2009).

  11. Control-centric Modelling and Nonlinear Control of the Blade Sailing Phenomenon

    Science.gov (United States)

    Riazi, Mohammad

    A reduced control-centric model of a particular behaviour associated with maritime helicopter rotor systems, known as Blade Sailing Phenomenon (BSP), is developed. BSP is a transient aeroelastic phenomenon described by the large undesired flapping motion of the helicopter rotor blades during low rotor speeds under high wind and elevated sea conditions. The developed model utilizes the Unified Airloads Model to capture the aerodynamic loads and the Intrinsic Nonlinear Beam Model to capture the structural behaviour of the blade. Integrally Actuated Twist (IAT) is used as the actuation strategy and a nonlinear feedback controller based on the Lyapunov stability theorem for autonomous dynamical systems is developed to counter the BSP. To evaluate the performance of the designed controller, the reduced BSP model is then discretized in the space domain using the Galerkin Spectral Discretization Method. The results prove the promising potential of the designed controller in countering the BSP in the reduced model. A further assessment of the controller is carried out by testing its performance in a comprehensive BSP model validated against experimental data. The results prove the capability of the controller to counter the BSP in a more accurate blade model and a more realistic simulation of a maritime environment.

  12. Hot Blade Cuttings for the Building Industries

    DEFF Research Database (Denmark)

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

    2016-01-01

    . The project aims to reduce the amount of manual labour as well as production time by applying robots to cut expanded polystyrene (EPS) moulds for the concrete to form doubly curved surfaces. The scheme is based upon the so-called Hot Wire or Hot Blade technology where the surfaces are essentially swept out...

  13. 49 CFR 236.707 - Blade, semaphore.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Blade, semaphore. 236.707 Section 236.707 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION...

  14. 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 las...

  15. Structural dynamic analysis of turbine blade

    Science.gov (United States)

    Antony, A. Daniel; Gopalsamy, M.; Viswanadh, Chaparala B. V.; Krishnaraj, R.

    2017-10-01

    In any gas turbine design cycle, blade design is a crucial element which needs maximum attention to meet the aerodynamic performance, structural safety margins, manufacturing feasibility, material availability etc. In present day gas turbine engines, most of the failures occur during engine development test and in-service, in rotor and stator blades due to fatigue and resonance failures. To address this issue, an extensive structural dynamic analysis is carried out to predict the natural frequencies and mode shapes using FE methods. Using the dynamics characteristics, the Campbell diagram is constructed to study the possibility of resonance at various operating speeds. In this work, the feasibility of using composite material in place of titanium alloy from the structural dynamics point of view. This is being attempted in a Low-pressure compressor where the temperatures are relatively low and fixed with the casings. The analysis will be carried out using FE method for different composite material with different lamina orientations chosen through the survey. This study will focus on the sensitivity of blade mode shapes to different laminae orientations, which will be used to alter the natural frequency and tailor the mode shapes. Campbell diagrams of existing titanium alloy are compared with the composite materials with different laminae at all critical operating conditions. The existing manufacturing methods and the proven techniques for blade profiles will also be discussed in this report.

  16. 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 it is ...

  17. Head injury from fan blades among children.

    Science.gov (United States)

    Alias, Azmi; Krishnapillai, Ravi; Teng, Hong Wah; Abd Latif, Ahmad Zubaidi; Adnan, Johari Siregar

    2005-07-01

    Head injury caused by fan blades is rare among children. We analysed 14 cases of such injury and discuss the causes, type of injury and preventive measures. A retrospective analysis of 14 cases of children who were admitted to the Pediatric Neurosurgical Unit of Hospital Kuala Lumpur after sustaining head injuries caused by fan blades between January 2000 and December 2002 was performed. The causes of fan-blade head injury included jumping on the upper bunk of a bunk-bed, climbing on a ladder, climbing up onto a table, and being lifted by an adult. Thirteen patients were injured by ceiling fans and one by falling onto an uncovered table fan. School-aged boys were the predominant victims. Mean patient age was 7.9 years (range, 1.0-12.2 years). There was a twin peak incidence of when the accidents occurred: just before lunch in the afternoon and bedtime at night. The types of injury were scalp lacerations, compound depressed fractures and multiple intracranial haemorrhages. Two patients had the complication of wound infection, and one of these patients developed cerebral spinal fluid leak. One patient died from severe head injuries. Safety awareness among parents and caretakers are important as fan-blade head injury among children is preventable.

  18. Mathematical Model of Two Blades System

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    2014-01-01

    Roč. 2, č. 4 (2014), s. 361-369 ISSN 2321-3558 R&D Projects: GA ČR GA101/09/1166 Institutional support: RVO:61388998 Keywords : turbine blades * dry friction * vibration damping * torsion Subject RIV: BI - Acoustics

  19. DEM Simulations of Granular Secondary Flow in Cylindrical Vertical Bladed Mixer – Effect of Blade Rake.

    OpenAIRE

    Trávníčková, T. (Tereza); Havlica, J. (Jaromír); Kohout, M.

    2016-01-01

    Mixing of granular systems is one of the most used chemical engineering unit operations. However, detailed description of the dynamics of granular flows through experiments is difficult. Therefore, usage of mathematical modeling increases. In this paper we deal with DEM (Discreet Element Method) simulations of mixing glass beads in a cylindrical vertical bladed mixer. The aim of this work is to describe the influence of blade rake on the development of granular secondary flows for different s...

  20. Family of airfoil shapes for rotating blades. [for increased power efficiency and blade stability

    Science.gov (United States)

    Noonan, K. W. (Inventor)

    1983-01-01

    An airfoil which has particular application to the blade or blades of rotor aircraft such as helicopters and aircraft propellers is described. The airfoil thickness distribution and camber are shaped to maintain a near zero pitching moment coefficient over a wide range of lift coefficients and provide a zero pitching moment coefficient at section Mach numbers near 0.80 and to increase the drag divergence Mach number resulting in superior aircraft performance.

  1. 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...

  2. Frequency-Weighted Model Predictive Control of Trailing Edge Flaps on a Wind Turbine Blade

    DEFF Research Database (Denmark)

    Castaignet, Damien; Couchman, Ian; Poulsen, Niels Kjølstad

    2013-01-01

    This paper presents the load reduction achieved with trailing edge flaps during a full-scale test on a Vestas V27 wind turbine. The trailing edge flap controller is a frequency-weighted linear model predictive control (MPC) where the quadratic cost consists of costs on the zero-phase filtered...... flapwise blade root moment and trailing edge flap deflection. Frequency-weighted MPC is chosen for its ability to handle constraints on the trailing edge flaps deflection, and to target at loads with given frequencies only. The controller is first tested in servo-aeroelastic simulations, before being...

  3. 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.

  4. 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......-way fluid-structure interaction method is introduced. A procedure combining finite element analysis and particle swarm algorithm to optimize composite structures of the wind turbine blade is developed. The procedure proposed not only allows thickness variation but also permits the spar cap location...

  5. Determination of Turbine Blade Life from Engine Field Data

    Science.gov (United States)

    Zaretsky, Erwin V.; Litt, Jonathan S.; Hendricks, Robert C.; Soditus, Sherry M.

    2013-01-01

    It is probable that no two engine companies determine the life of their engines or their components in the same way or apply the same experience and safety factors to their designs. Knowing the failure mode that is most likely to occur minimizes the amount of uncertainty and simplifies failure and life analysis. Available data regarding failure mode for aircraft engine blades, while favoring low-cycle, thermal-mechanical fatigue (TMF) as the controlling mode of failure, are not definitive. Sixteen high-pressure turbine (HPT) T-1 blade sets were removed from commercial aircraft engines that had been commercially flown by a single airline and inspected for damage. Each set contained 82 blades. The damage was cataloged into three categories related to their mode of failure: (1) TMF, (2) Oxidation/erosion (O/E), and (3) Other. From these field data, the turbine blade life was determined as well as the lives related to individual blade failure modes using Johnson-Weibull analysis. A simplified formula for calculating turbine blade life and reliability was formulated. The L10 blade life was calculated to be 2427 cycles (11 077 hr). The resulting blade life attributed to O/E equaled that attributed to TMF. The category that contributed most to blade failure was Other. If there were no blade failures attributed to O/E and TMF, the overall blade L(sub 10) life would increase approximately 11 to 17 percent.

  6. Development of 52 inch last stage blade for steam turbine

    International Nuclear Information System (INIS)

    Kadoya, Yoshiki; Harada, Masakatsu; Watanabe, Eiichiro

    1985-01-01

    Mitsubishi Heavy Industries, Ltd. has developed the last stage blades with 1320 mm length for a 1800 rpm LP turbine, and the verification by rotating vibration test using actual blades was finished, thus the blades were completed. In a nuclear power plant with an A-PWR of 3800 MW thermal output, the 1350 MW steam turbine has one HP turbine and three LP turbines coupled in tandem, and the optimum last stage blades for the LP turbines became the 1320 mm blades. The completion of these blades largely contributes to the improvement of thermal efficiency and the increase of generator output in large nuclear power plants, and has the possibility to decrease three LP turbines to two in 900 MW plants, which reduces the construction cost. The velocity energy of steam coming out of last stage blades is abandoned as exhaust loss in a condenser, which is the largest loss in a turbine. The increase of exhaust area using long blades reduces this loss. The economy of the 1320 mm blades, the features of the 1320 mm blades, the aerodynamic design and its verification, the prevention of the erosion of the 1320 mm blades due to wet steam, the strength design, the anti-vibration design and its verification, and the CAD/CAM system are reported. (Kako, I.)

  7. Antenna Gain Impact on UWB Wind Turbine Blade Deflection Sensing

    DEFF Research Database (Denmark)

    Zhang, Shuai; Franek, Ondrej; Byskov, Claus

    2018-01-01

    effective (or equivalent) isotropic radiated power (EIRP), an HG tip antenna inside a blade gives stronger direct pulse amplitudes and better pulse waveforms for accurate and reliable distance estimations than the LG. Moreover, the direct pulse with the HG antenna is also closer to the blade surface, which...... a blade). Higher antenna gain enlarges both direct pulse and multipath but in different levels. To verify the simulations, time-domain measurements are performed with a full 37-meter blade. Pulse waveforms and power delay profiles are measured. From all the studies, it follows that: with the similar......Antenna gain impact on UWB wind turbine blade deflection sensing is studied in this paper. Simulations are applied with a 4.5-meter blade tip. The antennas with high gain (HG) and low gain (LG) in free space are simulated inside a blade. It is interesting to find that tip antennas with HG and LG...

  8. Turbine blade squealer tip rail with fence members

    Science.gov (United States)

    Little, David A

    2012-11-20

    A turbine blade includes an airfoil, a blade tip section, a squealer tip rail, and a plurality of chordally spaced fence members. The blade tip section includes a blade tip floor located at an end of the airfoil distal from the root. The blade tip floor includes a pressure side and a suction side joined together at chordally spaced apart leading and trailing edges of the airfoil. The squealer tip rail extends radially outwardly from the blade tip floor adjacent to the suction side and extends from a first location adjacent to the airfoil trailing edge to a second location adjacent to the airfoil leading edge. The fence members are located between the airfoil leading and trailing edges and extend radially outwardly from the blade tip floor and axially from the squealer tip rail toward the pressure side.

  9. 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...

  10. Antenna Gain Impact on UWB Wind Turbine Blade Deflection Sensing

    DEFF Research Database (Denmark)

    Zhang, Shuai; Franek, Ondrej; Byskov, Claus

    2018-01-01

    effective (or equivalent) isotropic radiated power (EIRP), an HG tip antenna inside a blade gives stronger direct pulse amplitudes and better pulse waveforms for accurate and reliable distance estimations than the LG. Moreover, the direct pulse with the HG antenna is also closer to the blade surface, which...... in free space have similar realized gain when allocated inside blades, so that the emission power for the HG and LG antennas in blades can be the same. The antenna gain impacts on time-domain pulse waveforms and power distributions around a blade are carefully investigated (with the tip antenna inside...... a blade). Higher antenna gain enlarges both direct pulse and multipath but in different levels. To verify the simulations, time-domain measurements are performed with a full 37-meter blade. Pulse waveforms and power delay profiles are measured. From all the studies, it follows that: with the similar...

  11. Multivariate Modelling of Extreme Load Combinations for Wind Turbines

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov

    2015-01-01

    We demonstrate a model for estimating the joint probability distribution of two load components acting on a wind turbine blade cross section. The model addresses the problem of modelling the probability distribution of load time histories with large periodic components by dividing the signal...... into a periodic part and a perturbation term, where each part has a known probability distribution. The proposed model shows good agreement with simulated data under stationary conditions, and a design load envelope based on this model is comparable to the load envelope estimated using the standard procedure...... for determining contemporaneous loads. By defining a joint probability distribution and full return-period contours for multiple load components, the suggested procedure gives the possibility for determining the most critical loading direction in a blade cross section, or for carrying out reliability analysis...

  12. Probabilistic model for multi-axial load combinations for wind turbines

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov

    2016-01-01

    The article presents a model describing the joint probability distribution of multiple load components acting on a wind turbine blade cross section. The problem of modelling the probability distribution of load time histories with large periodic components is addressed by dividing the signal...... for determining contemporaneous loads. Using examples with simulated loads on a 10 MW wind turbine,the behavior of the bending moments acting on a blade section is illustrated under different conditions.The loading direction most critical for material failure is determined using a finite-element model...... of the blade cross section on which load combinations with different directions but with equal probability are applied. By defining a joint probability distribution and return-period contours for multiple load components,the suggested procedure is applicable to different aspects of the design of wind turbine...

  13. Investigation of the maximum load alleviation potential using trailing edge flaps controlled by inflow data

    DEFF Research Database (Denmark)

    Fischer, Andreas; Aagaard Madsen, Helge

    2014-01-01

    to time series from computations with the aeroelastic code HAWC2 and to measured time series. The fatigue loads could be reduced by 36% in the computations if the in flow sensor was at the same position as the blade load. The decrease of the load reduction potential when the sensor was at a distance from......The maximum fatigue load reduction potential when using trailing edge flaps on mega-watt wind turbines was explored. For this purpose an ideal feed forward control algorithm using the relative velocity and angle of attack at the blade to control the loads was implemented. The algorithm was applied...... the blade load location was investigated. When the algorithm was applied to measured time series a load reduction of 23% was achieved which is still promissing, but significantly lower than the value achieved in computations....

  14. Development of porous squeeze film damper bearings for improving the blade loss dynamics of rotor-support systems

    Science.gov (United States)

    Zhang, Shiping; Yan, Litang; Li, Qihan

    1992-07-01

    An efficient oil-film damper known as porous squeeze-film damper (PSFD) is developed based on conventional squeeze-film damper (SFD) for more effective and reliable rotor-vibration control and for improving the blade-loss dynamics for rotor-support systems. The permeability of the outer race of PSFD could remarkably improve the squeeze-film damping properties. The transient response of a simple rigid rotor and flexible Jeffcott's rotor supported on PSFD and SFD subjected to sudden unbalance of blade loss are investigated. Time-transient simulation shows that PSFD could operate effectively under much greater unbalance as compared with SFD, especially under relative large impact loading of blade loss. The effective eccentricities of PSFD with small transmissibilities extend to a range of epsilon of less than 0.9, and optimum film stiffness and damping distribution within the whole film clearance could be achieved.

  15. Numerical Validation of a Vortex Model against ExperimentalData on a Straight-Bladed Vertical Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    Eduard Dyachuk

    2015-10-01

    Full Text Available Cyclic blade motion during operation of vertical axis wind turbines (VAWTs imposes challenges on the simulations models of the aerodynamics of VAWTs. A two-dimensional vortex model is validated against the new experimental data on a 12-kW straight-bladed VAWT, which is operated at an open site. The results on the normal force on one blade are analyzed. The model is assessed against the measured data in the wide range of tip speed ratios: from 1.8 to 4.6. The predicted results within one revolution have a similar shape and magnitude as the measured data, though the model does not reproduce every detail of the experimental data. The present model can be used when dimensioning the turbine for maximum loads.

  16. Vibratory Loads Data from a Wind-Tunnel Test of Structurally Tailored Model Helicopter Rotors

    Science.gov (United States)

    Yeager, William T., Jr.; Hamouda, M-Nabil H.; Idol, Robert F.; Mirick, Paul H.; Singleton, Jeffrey D.; Wilbur, Matthew L.

    1991-01-01

    An experimental study was conducted in the Langley Transonic Dynamics Tunnel to investigate the use of a Bell Helicopter Textron (BHT) rotor structural tailoring concept, known as rotor nodalization, in conjunction with advanced blade aerodynamics as well as to evaluate rotor blade aerodynamic design methodologies. A 1/5-size, four-bladed bearingless hub, three sets of Mach-scaled model rotor blades were tested in forward flight from transition up to an advance ratio of 0.35. The data presented pertain only to the evaluation of the structural tailoring concept and consist of fixed-system and rotating system vibratory loads. These data will be useful for evaluating the effects of tailoring blade structural properties on fixed-system vibratory loads, as well as validating analyses used in the design of advanced rotor systems.

  17. Joint excitation synchronization characteristics of fatigue test for offshore wind turbine blade

    Science.gov (United States)

    Zhang, Lei-an; Yu, Xiang-yong; Wei, Xiu-ting; Liu, Wei-sheng

    2018-02-01

    In the case of the stiffness of offshore wind turbine blade is relatively large, the joint excitation device solves the problem of low accuracy of bending moment distribution, insufficient driving ability and long fatigue test period in single-point loading. In order to study the synchronous characteristics of joint excitation system, avoid blade vibration disturbance. First, on the base of a Lagrange equation, a mathematical model of combined excitation is formulated, and a numerical analysis of vibration synchronization is performed. Then, the model is constructed via MATLAB/Simulink, and the effect of the phase difference on the vibration synchronization characteristics is obtained visually. Finally, a set of joint excitation platform for the fatigue test of offshore wind turbine blades are built. The parameter measurement scheme is given and the correctness of the joint excitation synchronization in the simulation model is verified. The results show that when the rotational speed difference is 2 r/min, 30 r/min, the phase difference is 0, π/20, π/8 and π/4, as the rotational speed difference and the phase difference increase, the time required for the blade to reach a steady state is longer. When the phase difference is too large, the electromechanical coupling can no longer make the joint excitation device appear self-synchronizing phenomenon, so that the value of the phase difference develops toward a fixed value (not equal to 0), and the blade vibration disorder is serious, at this time, the effect of electromechanical coupling must be eliminated. The research results provide theoretical basis for the subsequent decoupling control algorithm and synchronization control strategy, and have good application value.

  18. Joint excitation synchronization characteristics of fatigue test for offshore wind turbine blade

    Directory of Open Access Journals (Sweden)

    Lei-an Zhang

    2018-02-01

    Full Text Available In the case of the stiffness of offshore wind turbine blade is relatively large, the joint excitation device solves the problem of low accuracy of bending moment distribution, insufficient driving ability and long fatigue test period in single-point loading. In order to study the synchronous characteristics of joint excitation system, avoid blade vibration disturbance. First, on the base of a Lagrange equation, a mathematical model of combined excitation is formulated, and a numerical analysis of vibration synchronization is performed. Then, the model is constructed via MATLAB/Simulink, and the effect of the phase difference on the vibration synchronization characteristics is obtained visually. Finally, a set of joint excitation platform for the fatigue test of offshore wind turbine blades are built. The parameter measurement scheme is given and the correctness of the joint excitation synchronization in the simulation model is verified. The results show that when the rotational speed difference is 2 r/min, 30 r/min, the phase difference is 0, π/20, π/8 and π/4, as the rotational speed difference and the phase difference increase, the time required for the blade to reach a steady state is longer. When the phase difference is too large, the electromechanical coupling can no longer make the joint excitation device appear self-synchronizing phenomenon, so that the value of the phase difference develops toward a fixed value (not equal to 0, and the blade vibration disorder is serious, at this time, the effect of electromechanical coupling must be eliminated. The research results provide theoretical basis for the subsequent decoupling control algorithm and synchronization control strategy, and have good application value.

  19. Interaction of turbulent length scales with wind turbine blades

    Science.gov (United States)

    Torres-Nieves, Sheilla N.

    Understanding the effects of free-stream turbulence (FST) and surface roughness on the flow around wind turbine blades is imperative in the quest for higher wind turbine efficiency, specially under stall conditions. While many investigations have focused on the aerodynamic loads on wind turbine airfoils, there are no studies that examine the effects of free-stream turbulence and surface roughness on the velocity field around a wind turbine airfoil. Hence, the aim of this investigation is to study the influence of high levels of FST on the flow around smooth and rough surfaces with pressure gradients. Moreover, of great importance in this study is the examination of how the length scales of turbulence and surface roughness interact in the flow over wind turbine airfoils to affect flow separation. Particle Image Velocimetry measurements were performed to analyze the overall flow around a S809 wind turbine blade. Results indicate that when the flow is fully attached, free-stream turbulence significantly decreases aerodynamic efficiency by 82%, yielding to higher loads and fatigue on the blades. On the contrary, when the flow is separated, the effect is reversed and aerodynamic performance is slightly improved (i.e., by 5%) by the presence of the free-stream turbulence. Analysis of the mean flow over the suction surface shows that, under stall conditions, free-stream turbulence delays separation, and surface roughness advances separation. Interestingly, the highly non-linear interaction between free-stream turbulence and surface roughness results in the further advancement of separation. Of particular interest is the study of the region closer to the wall (i.e., the boundary layer), where the flow interacts with both the surface of the blade and the free-stream. Turbulent boundary layer experiments subject to an external favorable pressure gradient (FPG) were performed to study the influence of FST, surface roughness and external pressure gradient (present around the

  20. In flight measurement of steady and unsteady blade surface pressure of a single rotation large scale advanced prop-fan installed on the PTA aircraft

    Science.gov (United States)

    Parzych, D.; Boyd, L.; Meissner, W.; Wyrostek, A.

    1991-01-01

    An experiment was performed by Hamilton Standard, Division of United Technologies Corporation, under contract by LeRC, to measure the blade surface pressure of a large scale, 8 blade model prop-fan in flight. The test bed was the Gulfstream 2 Prop-Fan Test Assessment (PTA) aircraft. The objective of the test was to measure the steady and periodic blade surface pressure resulting from three different Prop-Fan air inflow angles at various takeoff and cruise conditions. The inflow angles were obtained by varying the nacelle tilt angles, which ranged from -3 to +2 degrees. A range of power loadings, tip speeds, and altitudes were tested at each nacelle tilt angle over the flight Mach number range of 0.30 to 0.80. Unsteady blade pressure data tabulated as Fourier coefficients for the first 35 harmonics of shaft rotational frequency and the steady (non-varying) pressure component are presented.

  1. Optimal topology and experimental evaluation of PE materials for actively shunted GE polymer matrix fiber composite blades

    Science.gov (United States)

    Choi, Benjamin B.; Duffy, Kirsten; Kauffman, Jeffrey L.; Kray, Nicholas

    2012-04-01

    NASA Glenn Research Center (GRC), in collaboration with GE Aviation, has begun the development of a smart adaptive structure system with piezoelectric transducers to improve composite fan blade damping at resonances. Traditional resonant damping approaches may not be realistic for rotating frame applications such as engine blades. The limited space in which the blades reside in the engine makes it impossible to accommodate the circuit size required to implement passive resonant damping. Thus, we have developed a novel digital shunt scheme to replace the conventional electric passive shunt circuits. The digital shunt dissipates strain energy through the load capacitor on a power amplifier. GE designed and fabricated a variety of polymer matrix fiber composite (PMFC) test specimens. We investigated the optimal topology of PE sensors and actuators for each test specimen to discover the best PE transducer location for each target mode. Also a variety of flexible patches, which can conform to the blade surface, have been tested to identify the best performing piezoelectric patch. The active damping control achieved significant performance at target modes. This work has been highlighted by successful spin testing up to 5,000 rpm of subscale GEnx composite blades in GRC's Dynamic Spin Rig.

  2. Optimal Topology and Experimental Evaluation of Piezoelectric Materials for Actively Shunted General Electric Polymer Matrix Fiber Composite Blades

    Science.gov (United States)

    Choi, Benjamin B.; Duffy, Kirsten; Kauffman, Jeffrey L.; Kray, Nicholas

    2012-01-01

    NASA Glenn Research Center, in collaboration with GE Aviation, has begun the development of a smart adaptive structure system with piezoelectric (PE) transducers to improve composite fan blade damping at resonances. Traditional resonant damping approaches may not be realistic for rotating frame applications such as engine blades. The limited space in which the blades reside in the engine makes it impossible to accommodate the circuit size required to implement passive resonant damping. Thus, a novel digital shunt scheme has been developed to replace the conventional electric passive shunt circuits. The digital shunt dissipates strain energy through the load resistor on a power amplifier. General Electric (GE) designed and fabricated a variety of polymer matrix fiber composite (PMFC) test specimens. Investigating the optimal topology of PE sensors and actuators for each test specimen has revealed the best PE transducer location for each target mode. Also a variety of flexible patches, which can conform to the blade surface, have been tested to identify the best performing PE patch. The active damping control achieved significant performance at target modes. This work has been highlighted by successful spin testing up to 5000 rpm of subscale GEnx composite blades in Glenn s Dynamic Spin Rig.

  3. Coolant Density and Control Blade History Effects in Extended BWR Burnup Credit

    Energy Technology Data Exchange (ETDEWEB)

    Ade, Brian J [ORNL; Marshall, William BJ J [ORNL; Bowman, Stephen M [ORNL; Gauld, Ian C [ORNL; Ilas, Germina [ORNL; Martinez-Gonzalez, Jesus S [ORNL

    2015-01-01

    various locations and at varying degrees during BWR operation based on the core loading pattern. When present during depletion, control blades harden the neutron spectrum locally because they displace the moderator and absorb thermal neutrons. The investigation of the effect of control blades on post operational cask reactivity is documented herein, as is the effect of multiple (continuous and intermittent) exposure periods with control blades inserted. The coupled effects of control blade presence on power density, void profile, or burnup profile will be addressed in future work.

  4. Comparing Fatigue Life Estimations of Composite Wind Turbine Blades using different Fatigue Analysis Tools

    DEFF Research Database (Denmark)

    Ardila, Oscar Gerardo Castro; Lennie, Matthew; Branner, Kim

    2015-01-01

    In this paper, fatigue lifetime prediction of NREL 5MW reference wind turbine is presented. The fatigue response of materials used in selected blade cross sections was obtained by applying macroscopic fatigue approaches and assuming uniaxial stress states. Power production and parked load cases...... suggested by the IEC 61400-1 standard were studied employing different load time intervals and by using two novel fatigue tools called ALBdeS and BECAS+F. The aeroelastic loads were defined thought aeroelastic simulations performed with both FAST and HAWC2 tools. The stress spectra at each layer were...... calculated employing laminated composite theory and beam cross section methods. The Palmgren-Miner linear damage rule was used to calculate the accumulation damage. The theoretical results produced by both fatigue tools proved a prominent effect of analysed design load conditions on the estimated lifetime...

  5. A Pattern Recognition Approach to Acoustic Emission Data Originating from Fatigue of Wind Turbine Blades.

    Science.gov (United States)

    Tang, Jialin; Soua, Slim; Mares, Cristinel; Gan, Tat-Hean

    2017-11-01

    The identification of particular types of damage in wind turbine blades using acoustic emission (AE) techniques is a significant emerging field. In this work, a 45.7-m turbine blade was subjected to flap-wise fatigue loading for 21 days, during which AE was measured by internally mounted piezoelectric sensors. This paper focuses on using unsupervised pattern recognition methods to characterize different AE activities corresponding to different fracture mechanisms. A sequential feature selection method based on a k-means clustering algorithm is used to achieve a fine classification accuracy. The visualization of clusters in peak frequency-frequency centroid features is used to correlate the clustering results with failure modes. The positions of these clusters in time domain features, average frequency-MARSE, and average frequency-peak amplitude are also presented in this paper (where MARSE represents the Measured Area under Rectified Signal Envelope). The results show that these parameters are representative for the classification of the failure modes.

  6. Long duration blade loss simulations including thermal growths for dual-rotor gas turbine engine

    Science.gov (United States)

    Sun, Guangyoung; Palazzolo, Alan; Provenza, A.; Lawrence, C.; Carney, K.

    2008-09-01

    This paper presents an approach for blade loss simulation including thermal growth effects for a dual-rotor gas turbine engine supported on bearing and squeeze film damper. A nonlinear ball bearing model using the Hertzian formula predicts ball contact load and stress, while a simple thermal model estimates the thermal growths of bearing components during the blade loss event. The modal truncation augmentation method combined with a proposed staggered integration scheme is verified through simulation results as an efficient tool for analyzing a flexible dual-rotor gas turbine engine dynamics with the localized nonlinearities of the bearing and damper, with the thermal growths and with a flexible casing model. The new integration scheme with enhanced modeling capability reduces the computation time by a factor of 12, while providing a variety of solutions with acceptable accuracy for durations extending over several thermal time constants.

  7. Helicopter Non-Unique Trim Strategies for Blade-Vortex Interaction (BVI) Noise Reduction

    Science.gov (United States)

    Malpica, Carlos; Greenwood, Eric; Sim, Ben W.

    2016-01-01

    An acoustics parametric analysis of the effect of fuselage drag and pitching moment on the Blade-Vortex Interaction (BVI) noise radiated by a medium lift helicopter (S-70UH-60) in a descending flight condition was conducted. The comprehensive analysis CAMRAD II was used for the calculation of vehicle trim, wake geometry and integrated air loads on the blade. The acoustics prediction code PSU-WOPWOP was used for calculating acoustic pressure signatures for a hemispherical grid centered at the hub. This paper revisits the concept of the X-force controller for BVI noise reduction, and investigates its effectiveness on an S-70 helicopter. The analysis showed that further BVI noise reductions were achievable by controlling the fuselage pitching moment. Reductions in excess of 6 dB of the peak BVI noise radiated towards the ground were demonstrated by compounding the effect of airframe drag and pitching moment simultaneously.

  8. Full-Scale Field Test of a Blade-Integrated Dual-Telescope Wind Lidar

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Sjöholm, Mikael; Angelou, Nikolas

    Introduction In recent years the use of wind lidars mounted directly on wind turbines has received increasing attention, and such systems are becoming commercially available. One aim of turbine-mounted wind lidars is to use them for prevision in connection with advanced feed-forward control systems...... for load reduction and power optimization. To date, main attention has been on control schemes where measurements of wind speeds and direction upwind are used for yaw and speed corrections. In this study we investigate experimentally the feasibility of using lidars integrated in the turbine blades...... in the top and bottom of the rotor plane. Conclusion We present here what we believe is the first successful wind speed measurements from a dual-telescope lidar installed on the blade of an operating wind turbine. The full-scale field test performed in the summer of 2012 has clearly demonstrated...

  9. Validation and modification of the Blade Element Momentum theory based on comparisons with actuator disc simulations

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Bak, Christian; Døssing, Mads

    2010-01-01

    A comprehensive investigation of the Blade Element Momentum (BEM) model using detailed numerical simulations with an axis symmetric actuator disc (AD) model has been carried out. The present implementation of the BEM model is in a version where exactly the same input in the form of non-dimensiona......A comprehensive investigation of the Blade Element Momentum (BEM) model using detailed numerical simulations with an axis symmetric actuator disc (AD) model has been carried out. The present implementation of the BEM model is in a version where exactly the same input in the form of non...... although the loading is uniform. Based on the findings we derived two small engineering sub-models to be included in the BEM model to account for the physical mechanisms causing the deviations. Finally, the influence of using the corrected BEM model, BEMcor on two rotor designs is presented. Copyright...

  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......The constructions of advanced architectural designs are presently very labour intensive, time consuming, and expensive. They are therefore only applied to a few prestige projects, and it is a major challenge for the building industry to bring the costs down and thereby offer the architects more....... The project aims to reduce the amount of manual labour as well as production time by applying robots to cut expanded polystyrene (EPS) moulds for the concrete to form doubly curved surfaces. The scheme is based upon the so-called Hot Wire or Hot Blade technology where the surfaces are essentially swept out...

  11. The Finite-Bladed Betz Rotor

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær

    2016-01-01

    The finite-bladed optimum Betz rotor is treated. It is first very recently that a complete description of this rotor has been derived. In the chapter, a full analytical solution to the Betz rotor problem will be given, and the results will be compared to other optimum rotor models, both with resp......The finite-bladed optimum Betz rotor is treated. It is first very recently that a complete description of this rotor has been derived. In the chapter, a full analytical solution to the Betz rotor problem will be given, and the results will be compared to other optimum rotor models, both...... with respect to performance and resulting rotor geometry. It is here shown that for tip speed ratios greater than three, all models result in the same geometry at the outer part of the rotor, whereas the inner part always is different, both with respect to plan form and with respect to twist distribution....

  12. Optical measurement of unducted fan blade deflections

    Science.gov (United States)

    Kurkov, A. P.

    1990-01-01

    A nonintrusive optical method for measuring unducted fan (or propeller) blade deflections is described and evaluated. The measurement does not depend on blade surface reflectivity. Deflection of a point at the leading edge and a point at the trailing edge in a plane nearly perpendicular to the pitch axis is obtained with a single light beam generated by a low-power, helium-neon laser. Quantitative analyses are performed from taped signals on a digital computer. Averaging techniques are employed to reduce random errors. Measured static deflections from a series of high-speed wind tunnel tests of a counterrotating unducted fan model are compared with available, predicted deflections, which are also used to evaluate systematic errors.

  13. Structural Reliability of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov

    and design. Reliability-based analysis methods have the potential of being a valuable tool which can improve the state of knowledge by explaining the uncertainties, and form the probabilistic basis for calibration of deterministic design tools. The present thesis focuses on reliability-based design of wind...... turbine blades. The main purpose is to draw a clear picture of how reliability-based design of wind turbines can be done in practice. The objectives of the thesis are to create methodologies for efficient reliability assessment of composite materials and composite wind turbine blades, and to map...... the uncertainties in the processes, materials and external conditions that have an effect on the health of a composite structure. The study considers all stages in a reliability analysis, from defining models of structural components to obtaining the reliability index and calibration of partial safety factors...

  14. A Take Stock of Turbine Blades Failure Phenomenon

    Science.gov (United States)

    Roy, Abhijit

    2018-02-01

    Turbine Blade design and engineering is one of the most complicated and important aspects of turbine technology. Experiments with blades can be simple or very complicated, depending upon parameters of analysis. Turbine blades are subjected to vigorous environments, such as high temperatures, high stresses, and a potentially high vibration environment. All these factors can lead to blade failures, which can destroy the turbine, and engine, so careful design is the prime consideration to resist those conditions. A high cycle of fatigue of compressor and turbine blades due to high dynamic stress caused by blade vibration and resonance within the operating range of machinery is common failure mode for turbine machine. Continuous study and investigation on failure of turbine blades are going on since last five decades. Some review papers published during these days aiming to present a review on recent studies and investigations done on failures of turbine blades. All the detailed literature related with the turbine blades has not been described but emphasized to provide all the methodologies of failures adopted by various researches to investigate turbine blade. This paper illustrate on various factors of failure.

  15. 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. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  16. Vibration of circular bladed disk with imperfections

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    2011-01-01

    Roč. 21, č. 10 (2011), s. 2893-2904 ISSN 0218-1274 R&D Projects: GA ČR GA101/09/1166 Institutional research plan: CEZ:AV0Z20760514 Keywords : circular bladed disk * vibration * imperfection * nonlinear damping Subject RIV: BI - Acoustics Impact factor: 0.755, year: 2011 http://www.worldscinet.com/ijbc/21/2110/S0218127411030210.html

  17. 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.

  18. 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)

  19. Load modeling for sharp V-cutter cutting litchi ( Litchi chinensis Sonn ...

    African Journals Online (AJOL)

    harvesting. Cutting load is a key parameter for 'hand-held auto-picker' operation. However, there is still no suitable model for cutting load setting. Hence, a model describing the relationship among cutting load, blade angle and friction coefficient was developed for cutting operation by sharp V-cutters. The model was based ...

  20. Damage detection in carbon composite material typical of wind turbine blades using auto-associative neural networks

    Science.gov (United States)

    Dervilis, N.; Barthorpe, R. J.; Antoniadou, I.; Staszewski, W. J.; Worden, K.

    2012-04-01

    The structure of a wind turbine blade plays a vital role in the mechanical and structural operation of the turbine. As new generations of offshore wind turbines are trying to achieve a leading role in the energy market, key challenges such as a reliable Structural Health Monitoring (SHM) of the blades is significant for the economic and structural efficiency of the wind energy. Fault diagnosis of wind turbine blades is a "grand challenge" due to their composite nature, weight and length. The damage detection procedure involves additional difficulties focused on aerodynamic loads, environmental conditions and gravitational loads. It will be shown that vibration dynamic response data combined with AANNs is a robust and powerful tool, offering on-line and real time damage prediction. In this study the features used for SHM are Frequency Response Functions (FRFs) acquired via experimental methods based on an LMS system by which identification of mode shapes and natural frequencies is accomplished. The methods used are statistical outlier analysis which allows a diagnosis of deviation from normality and an Auto-Associative Neural Network (AANN). Both of these techniques are trained by adopting the FRF data for normal and damage condition. The AANN is a method which has not yet been widely used in the condition monitoring of composite materials of blades. This paper is trying to introduce a new scheme for damage detection, localisation and severity assessment by adopting simple measurements such as FRFs and exploiting multilayer neural networks and outlier novelty detection.

  1. Abrasive wear of ploughshare blades made of Austempered Ductile Iron

    Directory of Open Access Journals (Sweden)

    Jiří Votava

    2007-01-01

    Full Text Available The objective of this article consists in exhaustive monitoring of abrasive wear and subsequent evaluation of nodular cast iron with spheroidal graphite used as the base material for production of ploughshare blades. Nodular cast iron has a lot of convenient properties for production of these components. We have tested this material in field tests. For these tests there were manufactured ploughshare blades (directly according to original. These ploughshare blades were tested in practical conditions of agricultural company Farma Nedvězí Ltd. Three ploughshare blades were used in natural cast state and the others were heat-treated. During the test there were measured decreases of weights of the ploughshare blades and subsequently compared with decreases of original ploughshare blades, produced by company Opall Agri which are ordinarily available at our market.

  2. Influence of atmospheric stability on wind turbine loads

    DEFF Research Database (Denmark)

    Sathe, Ameya; Mann, Jakob; Barlas, Thanasis K.

    2013-01-01

    at the turbine hub height. The loads are quantified as the cumulative sum of the damage equivalent load for different wind speeds that are weighted according to the wind speed and stability distribution. Four sites with a different wind speed and stability distribution are used for comparison. The turbulence...... turbulent energy. The tower base loads are mainly influenced by diabatic turbulence, whereas the rotor loads are influenced by diabatic wind profiles. The blade loads are influenced by both, diabatic wind profile and turbulence, that leads to nullifying the contrasting influences on the loads...

  3. Active Piezoelectric Vibration Control of Subscale Composite Fan Blades

    Science.gov (United States)

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

    2012-01-01

    As part of the Fundamental Aeronautics program, researchers at NASA Glenn Research Center (GRC) are investigating new technologies supporting the development of lighter, quieter, and more efficient fans for turbomachinery applications. High performance fan blades designed to achieve such goals will be subjected to higher levels of aerodynamic excitations which could lead to more serious and complex vibration problems. Piezoelectric materials have been proposed as a means of decreasing engine blade vibration either through a passive damping scheme, or as part of an active vibration control system. For polymer matrix fiber composite blades, the piezoelectric elements could be embedded within the blade material, protecting the brittle piezoceramic material from the airflow and from debris. To investigate this idea, spin testing was performed on two General Electric Aviation (GE) subscale composite fan blades in the NASA GRC Dynamic Spin Rig Facility. The first bending mode (1B) was targeted for vibration control. Because these subscale blades are very thin, the piezoelectric material was surface-mounted on the blades. Three thin piezoelectric patches were applied to each blade two actuator patches and one small sensor patch. These flexible macro-fiber-composite patches were placed in a location of high resonant strain for the 1B mode. The blades were tested up to 5000 rpm, with patches used as sensors, as excitation for the blade, and as part of open- and closed-loop vibration control. Results show that with a single actuator patch, active vibration control causes the damping ratio to increase from a baseline of 0.3% critical damping to about 1.0% damping at 0 RPM. As the rotor speed approaches 5000 RPM, the actively controlled blade damping ratio decreases to about 0.5% damping. This occurs primarily because of centrifugal blade stiffening, and can be observed by the decrease in the generalized electromechanical coupling with rotor speed.

  4. 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

  5. Modal characteristics and fatigue strength of compressor blades

    International Nuclear Information System (INIS)

    Kim, Kyung Kook; Lee, Young Shin

    2014-01-01

    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.

  6. Composite Fan Blade Design for Advanced Engine Concepts

    Science.gov (United States)

    Abumeri, Galib H.; Kuguoglu, Latife H.; Chamis, Christos C.

    2004-01-01

    The aerodynamic and structural viability of composite fan blades of the revolutionary Exo-Skeletal engine are assessed for an advanced subsonic mission using the NASA EST/BEST computational simulation system. The Exo-Skeletal Engine (ESE) calls for the elimination of the shafts and disks completely from the engine center and the attachment of the rotor blades in spanwise compression to a rotating casing. The fan rotor overall adiabatic efficiency obtained from aerodynamic analysis is estimated at 91.6 percent. The flow is supersonic near the blade leading edge but quickly transitions into a subsonic flow without any turbulent boundary layer separation on the blade. The structural evaluation of the composite fan blade indicates that the blade would buckle at a rotor speed that is 3.5 times the design speed of 2000 rpm. The progressive damage analysis of the composite fan blade shows that ply damage is initiated at a speed of 4870 rpm while blade fracture takes place at 7640 rpm. This paper describes and discusses the results for the composite blade that are obtained from aerodynamic, displacement, stress, buckling, modal, and progressive damage analyses. It will be demonstrated that a computational simulation capability is readily available to evaluate new and revolutionary technology such as the ESE.

  7. 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...... to this problem is elastic blade coatings, which are able to absorb the impact energy without crack formation. The purpose of the work presented in this thesis has been to design and construct a laboratory experimentation device, which allows an accelerated and reliable evaluation of existing or novel blade...

  8. 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.

  9. A review of research in rotor loads

    Science.gov (United States)

    Bousman, William G.; Mantay, Wayne R.

    1988-01-01

    The research accomplished in the area of rotor loads over the last 13 to 14 years is reviewed. The start of the period examined is defined by the 1973 AGARD Milan conference and the 1974 hypothetical rotor comparison. The major emphasis of the review is research performed by the U.S. Army and NASA at their laboratories and/or by the industry under government contract. For the purpose of this review, two main topics are addressed: rotor loads prediction and means of rotor loads reduction. A limited discussion of research in gust loads and maneuver loads is included. In the area of rotor loads predictions, the major problem areas are reviewed including dynamic stall, wake induced flows, blade tip effects, fuselage induced effects, blade structural modeling, hub impedance, and solution methods. It is concluded that the capability to predict rotor loads has not significantly improved in this time frame. Future progress will require more extensive correlation of measurements and predictions to better understand the causes of the problems, and a recognition that differences between theory and measurement have multiple sources, yet must be treated as a whole. There is a need for high-quality data to support future research in rotor loads, but the resulting data base must not be seen as an end in itself. It will be useful only if it is integrated into firm long-range plans for the use of the data.

  10. Main Factors Affecting Blade Failure of Marine Propeller(2nd Report:Resonance between Vibrations of Propeller Shaft and Blade)

    OpenAIRE

    川添, 強; 松尾, 信太郎; 錦戸, 真吾

    1994-01-01

    The first report showed the difficulty to consider the small material defects and the low fluctuating stress by the hydrodynamic force as the main factors of the propeller blade failure. For the purpose of the elucidation of resonance between vibrations of the propeller shaft and the propeller blade, this paper presents the measurements and calculations of the flexural natural frequency of the full scale propeller blade in .air and in water, the vibratory stress due to the resonance and the l...

  11. 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.

  12. Methods and apparatus for reduction of asymmetric rotor loads in wind turbines

    Science.gov (United States)

    Moroz, Emilian Mieczyslaw; Pierce, Kirk Gee

    2006-10-10

    A method for reducing load and providing yaw alignment in a wind turbine includes measuring displacements or moments resulting from asymmetric loads on the wind turbine. These measured displacements or moments are used to determine a pitch for each rotor blade to reduce or counter asymmetric rotor loading and a favorable yaw orientation to reduce pitch activity. Yaw alignment of the wind turbine is adjusted in accordance with the favorable yaw orientation and the pitch of each rotor blade is adjusted in accordance with the determined pitch to reduce or counter asymmetric rotor loading.

  13. Blade Vibration Measurement System for Characterization of Closely Spaced Modes and Mistuning, Phase I

    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...

  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. 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......The present report describes the work done in work package WP3.3: Aerodynamic Accessories in 3D in the EC project KNOW-BLADE. Vortex generators (VGs) are modelled in 3D Navier-Stokes solvers and applied on the flow around an airfoil and a wind turbineblade. Three test cases have been investigated...... of the partners have modelled the airfoil section as a thin airfoil section with symmetry boundary conditions in the span wise direction to simulate anarray of VGs. The wind turbine blade is the LM19.1 blade equipped with one pair of VGs placed at radius = 8.5 m. In general all partners have successfully modelled...

  16. The blade element momentum (BEM) method

    DEFF Research Database (Denmark)

    Branlard, Emmanuel Simon Pierre

    2017-01-01

    The current chapter presents the blade element momentum (BEM) method. The BEM method for a steady uniform inflow is presented in a first section. Some of the ad-hoc corrections that are usually added to the algorithm are discussed in a second section. An exception is made to the tip-loss correction...... which is introduced early in the algorithm formulation for practical reasons. The ad-hoc corrections presented are: the tip-loss correction, the high-thrust correction (momentum breakdown) and the correction for wake rotation. The formulation of an unsteady BEM code is given in a third section...

  17. Atmospheric Plasma Blade for Surgical Purposes

    Science.gov (United States)

    Oksuz, Lutfi; Yurdabak Karaca, Gozde; Özkaptan, Emir; Uygun, Emre; Uygun Oksuz, Aysegul

    2017-10-01

    Atmospheric plasma cut is a process at the minimum level due to the ions, radicals and free electrons generated by the active electrode and target tissue. Atmospheric plasma cutting devices provide significant advantages as a non-contact electrocautery system that can operate in isotonic environment. During operations where plasma cutting is applied, bleeding is controlled and the side effects that would create the isotonic environment are eliminated. In this study in vivo and in vitro studies will be carried out by producing and optimizing the atmospheric plasma blade. Once the optimum parameters of the instrument are determined, in vivo studies will be performed and the pathology results will be evaluated.

  18. Analysis of time domain active sensing data from CX-100 wind turbine blade fatigue tests for damage assessment

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Mi Jin [Dept. of Aerospace Engineering and LANL-CBNU Engineering Institute, Chunbuk National University, Jeonju (Korea, Republic of); Jung, Hwee Kwon; Park, Gyu Hae [School of Mechanical Engineering, Chonnam National University, Gwangju (Korea, Republic of); Taylor, Stuart G.; Farinholt, Kevin M. [The Engineering Institute, Los Alamos National Laboratory, Los Alamos (United States)

    2016-04-15

    This paper presents the results obtained using time-series-based methods for structural damage assessment. The methods are applied to a wind turbine blade structure subjected to fatigue loads. A 9 m CX-100 (carbon experimental 100 kW) blade is harmonically excited at its first natural frequency to introduce a failure mode. Consequently, a through-thickness fatigue crack is visually identified at 8.5 million cycles. The time domain data from the piezoelectric active-sensing techniques are measured during the fatigue loadings and used to detect incipient damage. The damage-sensitive features, such as the first four moments and a normality indicator, are extracted from the time domain data. Time series autoregressive models with exogenous inputs are also implemented. These features could efficiently detect a fatigue crack and are less sensitive to operational variations than the other methods.

  19. 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.

  20. Blade profile optimization of kaplan turbine using cfd analysis

    International Nuclear Information System (INIS)

    Janjua, A.B.; Khalil, M.S.

    2013-01-01

    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. (author)

  1. 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.

  2. Innovative design approaches for large wind turbine blades

    Science.gov (United States)

    Jackson, K. J.; Zuteck, M. D.; van Dam, C. P.; Standish, K. J.; Berry, D.

    2005-04-01

    A preliminary design study of an advanced 50 m blade for utility wind turbines is presented and discussed. The effort was part of the Department of Energy WindPACT Blade System Design Study with the goal to investigate and evaluate design and manufacturing issues for wind turbine blades in the 1-10 MW size range. Two different blade designs are considered and compared in this article. The first is a fibreglass design, while the second design selectively incorporates carbon fibre in the main structural elements. The addition of carbon results in modest cost increases and provides significant benefits, particularly with respect to blade deflection. The structural efficiency of both designs was maximized by tailoring the thickness of the blade cross-sections to simplify the construction of the internal members. Inboard the blades incorporate thick blunt trailing edge aerofoils (flatback aerofoils), while outboard more conventional sharp trailing edge high-lift aerofoils are used. The outboard section chord lengths were adjusted to yield the least complex and costly internal blade structure. 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 studs has a positive effect on total weight, because it reduces the required root laminate thickness. The aerodynamic performance of the blade aerofoils was predicted using computational techniques that properly simulate blunt trailing edge flows. The performance of the rotor was predicted assuming both clean and soiled blade surface conditions. The rotor is shown to provide excellent performance at a weight significantly lower than that of current rotors of this size. Copyright

  3. Modeling dynamic stall on wind turbine blades under rotationally augmented flow fields

    Energy Technology Data Exchange (ETDEWEB)

    Guntur, S. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schreck, S. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sorensen, N. N. [Technical Univ. of Denmark, Lyngby (Denmark); Bergami, L. [Technical Univ. of Denmark, Lyngby (Denmark)

    2015-04-22

    It is well known that airfoils under unsteady flow conditions with a periodically varying angle of attack exhibit aerodynamic characteristics different from those under steady flow conditions, a phenomenon commonly known as dynamic stall. It is also well known that the steady aerodynamic characteristics of airfoils in the inboard region of a rotating blade differ from those under steady two-dimensional (2D) flow conditions, a phenomenon commonly known as rotational augmentation. This paper presents an investigation of these two phenomena together in the inboard parts of wind turbine blades. This analysis is carried out using data from three sources: (1) the National Renewable Energy Laboratory’s Unsteady Aerodynamics Experiment Phase VI experimental data, including constant as well as continuously pitching blade conditions during axial operation, (2) data from unsteady Delayed Detached Eddy Simulations (DDES) carried out using the Technical University of Denmark’s in-house flow solver Ellipsys3D, and (3) data from a simplified model based on the blade element momentum method with a dynamic stall subroutine that uses rotationally augmented steady-state polars obtained from steady Phase VI experimental sequences, instead of the traditional 2D nonrotating data. The aim of this work is twofold. First, the blade loads estimated by the DDES simulations are compared to three select cases of the N sequence experimental data, which serves as a validation of the DDES method. Results show reasonable agreement between the two data in two out of three cases studied. Second, the dynamic time series of the lift and the moment polars obtained from the experiments are compared to those from the dynamic stall subroutine that uses the rotationally augmented steady polars. This allowed the differences between the stall phenomenon on the inboard parts of harmonically pitching blades on a rotating wind turbine and the classic dynamic stall representation in 2D flow to be

  4. Study on Unified Chaotic System-Based Wind Turbine Blade Fault Diagnostic System

    Science.gov (United States)

    Kuo, Ying-Che; Hsieh, Chin-Tsung; Yau, Her-Terng; Li, Yu-Chung

    At present, vibration signals are processed and analyzed mostly in the frequency domain. The spectrum clearly shows the signal structure and the specific characteristic frequency band is analyzed, but the number of calculations required is huge, resulting in delays. Therefore, this study uses the characteristics of a nonlinear system to load the complete vibration signal to the unified chaotic system, applying the dynamic error to analyze the wind turbine vibration signal, and adopting extenics theory for artificial intelligent fault diagnosis of the analysis signal. Hence, a fault diagnostor has been developed for wind turbine rotating blades. This study simulates three wind turbine blade states, namely stress rupture, screw loosening and blade loss, and validates the methods. The experimental results prove that the unified chaotic system used in this paper has a significant effect on vibration signal analysis. Thus, the operating conditions of wind turbines can be quickly known from this fault diagnostic system, and the maintenance schedule can be arranged before the faults worsen, making the management and implementation of wind turbines smoother, so as to reduce many unnecessary costs.

  5. Low cycle fatigue analysis of a last stage steam turbine blade

    Directory of Open Access Journals (Sweden)

    Měšťánek P.

    2008-11-01

    Full Text Available The present paper deals with the low cycle fatigue analysis of the low pressure (LP steam turbine blade. The blade is cyclically loaded by the centrifugal force because of the repeated startups of the turbine. The goal of the research is to develop a technique to assess fatigue life of the blade and to determine the number of startups to the crack initiation. Two approaches were employed. First approach is based on the elastic finite element analysis. Fictive 'elastic' results are recalculated using Neuber's rule and the equivalent energy method. Triaxial state of stress is reduced using von Mises theory. Strain amplitude is calculated employing the cyclic deformation curve. Second approach is based on elastic-plastic FE analysis. Strain amplitude is determined directly from the FE analysis by reducing the triaxial state of strain. Fatigue life was assessed using uniaxial damage parameters. Both approaches are compared and their applicability is discussed. Factors that can influence the fatigue life are introduced. Experimental low cycle fatigue testing is shortly described.

  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. Convective heat transfer and experimental icing aerodynamics of wind turbine blades

    Science.gov (United States)

    Wang, Xin

    The total worldwide base of installed wind energy peak capacity reached 94 GW by the end of 2007, including 1846 MW in Canada. Wind turbine systems are being installed throughout Canada and often in mountains and cold weather regions, due to their high wind energy potential. Harsh cold weather climates, involving turbulence, gusts, icing and lightning strikes in these regions, affect wind turbine performance. Ice accretion and irregular shedding during turbine operation lead to load imbalances, often causing the turbine to shut off. They create excessive turbine vibration and may change the natural frequency of blades as well as promote higher fatigue loads and increase the bending moment of blades. Icing also affects the tower structure by increasing stresses, due to increased loads from ice accretion. This can lead to structural failures, especially when coupled to strong wind loads. Icing also affects the reliability of anemometers, thereby leading to inaccurate wind speed measurements and resulting in resource estimation errors. Icing issues can directly impact personnel safety, due to falling and projected ice. It is therefore important to expand research on wind turbines operating in cold climate areas. This study presents an experimental investigation including three important fundamental aspects: (1) heat transfer characteristics of the airfoil with and without liquid water content (LWC) at varying angles of attack; (2) energy losses of wind energy while a wind turbine is operating under icing conditions; and (3) aerodynamic characteristics of an airfoil during a simulated icing event. A turbine scale model with curved 3-D blades and a DC generator is tested in a large refrigerated wind tunnel, where ice formation is simulated by spraying water droplets. A NACA 63421 airfoil is used to study the characteristics of aerodynamics and convective heat transfer. The current, voltage, rotation of the DC generator and temperature distribution along the airfoil

  8. Study of blade aspect ratio on a compressor front stage aerodynamic and mechanical design report

    Science.gov (United States)

    Burger, G. D.; Lee, D.; Snow, D. W.

    1979-01-01

    A single stage compressor was designed with the intent of demonstrating that, for a tip speed and hub-tip ratio typical of an advanced core compressor front stage, the use of low aspect ratio can permit high levels of blade loading to be achieved at an acceptable level of efficiency. The design pressure ratio is 1.8 at an adiabatic efficiency of 88.5 percent. Both rotor and stator have multiple-circular-arc airfoil sections. Variable IGV and stator vanes permit low speed matching adjustments. The design incorporates an inlet duct representative of an engine transition duct between fan and high pressure compressor.

  9. Examination of forced unsteady separated flow fields on a rotating wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Huyer, S [Univ. of Colorado, Boulder, CO (US)

    1993-04-01

    The wind turbine industry faces many problems regarding the construction of efficient and predictable wind turbine machines. Steady state, two-dimensional wind tunnel data are generally used to predict aerodynamic loads on wind turbine blades. Preliminary experimental evidence indicates that some of the underlying fluid dynamic phenomena could be attributed to dynamic stall, or more specifically to generation of forced unsteady separated flow fields. A collaborative research effort between the University of Colorado and the National Renewable Energy Laboratory was conducted to systematically categorize the local and global effects of three- dimensional forced unsteady flow fields.

  10. Numerical Investigations of the Influence of Unsteady Vane Trailing Edge Shock Wave on Film Cooling Effectiveness of Rotor Blade Leading Edge

    Science.gov (United States)

    Wang, Yufeng; Cai, Le; Wang, Songtao; Zhou, Xun

    2018-04-01

    Unsteady numerical simulations of a high-load transonic turbine stage have been carried out to study the influences of vane trailing edge outer-extending shockwave on rotor blade leading edge film cooling performance. The turbine stage used in this paper is composed of a vane section and a rotor one which are both near the root section of a transonic high-load turbine stage. The Mach number is 0.94 at vane outlet, and the relative Mach number is above 1.10 at rotor outlet. Various positions and oblique angles of film cooling holes were investigated in this research. Results show that the cooling efficiency on the blade surface of rotor near leading edge is significantly affected by vane trailing edge outer-extending shockwave in some cases. In the cases that film holes are close to leading edge, cooling performance suffers more from the sweeping vane trailing edge outer-extending shockwave. In addition, coolant flow ejected from oblique film holes is harder to separate from the blade surface of rotor, and can cover more blade area even under the effects of sweeping vane trailing edge shockwave. As a result, oblique film holes can provide better film cooling performance than vertical film holes do near the leading edge on turbine blade which is swept by shockwaves.

  11. 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.

  12. Analysis of rotating flexible blades using MSC/NASTRAN

    Science.gov (United States)

    Ernst, Michael A.

    1988-01-01

    An overview is given of the use of MSC/NASTRAN in the analysis of rotating flexible blades. The geometrically nonlinear analysis using NASTRAN Solution Sequence 64 is discussed along with the determination of frequencies and mode shapes using Solution Sequence 63. Items unique to rotating blade analysis, such as setting angle, centrifugal softening effects, and hub flexibility, are emphasized.

  13. Bacterial contamination of re-usable laryngoscope blades during the ...

    African Journals Online (AJOL)

    We aimed to assess the level of microbial contamination of re-usable laryngoscope blades at a public hospital in South Africa. Setting. The theatre complex of a secondary-level public hospital in Johannesburg. Methods. Blades from two different theatres were sampled twice daily, using a standardised technique, over a ...

  14. Damage detection in wind turbine blades using acoustic techniques

    International Nuclear Information System (INIS)

    Juengert, A.

    2013-01-01

    Facing climate change, the use of renewable energy gains importance. The wind energy sector grows very fast. Bigger and more powerful wind turbines will be built in the coming decades and the safety and reliability of the turbines will become more important. Wind turbine blades have to be inspected at regular intervals, because they are highly stressed during operation and a blade breakdown can cause big economic damages. The turbine blades consist of fiber reinforced plastics (GFRP/CFRP) and sandwich areas containing wood or plastic foam. The blades are manufactured as two halves and glued together afterwards. Typical damages are delaminations within the GFRP or the sandwich and missing adhesive or deficient bond at the bonding surfaces. The regular inspections of wind turbine blades are performed manually by experts and are limited to visual appraisals and simple tapping tests. To improve the inspections of wind turbine blades non-destructive testing techniques using acoustic waves are being developed. To detect delaminations within the laminates of the turbine blade, a local resonance spectroscopy was used. To detect missing bond areas from the outside of the blade the impulse-echo-technique was applied. This paper is an updated reprint of an article published on ndt.net in 2008. (author)

  15. IEC-TC88WG8 testing of rotor blades

    Energy Technology Data Exchange (ETDEWEB)

    Delft, D.R.V. van [Delft Univ. of Technology, STEVIN Lab., Delft (Netherlands)

    1996-09-01

    In 1994 the TC88 of IEC installed a working group (WG8) to draft a guideline on blade testing. This paper gives a description of the task of the working group. Furthermore it gives a report of the progress of the work and summarizes the possible contents of the working group document on blade testing. (au)

  16. Selection of a high performance alloy for gas turbine blade using finite element methods

    International Nuclear Information System (INIS)

    Khawaja, H.A.; Khan, A.M.; Ali, S.T.

    2007-01-01

    With the extensive increase in the utilization of energy resources in the modern era, the need of energy extraction from various resources has pronounced in recent years. Thus comprehensive efforts have been made around the globe in the technological development of turbo machines where means of energy extraction is energized fluids. This development led the eviation industry to power boost due to better performing engines. Meanwhile, the structural conformability requirements relative to the functional requirements have also increased with the advent of newer, better performing materials. Thus there is a need to study the material behavior and its usage with the idea of selecting the best possible material for its application. In this work a gas turbine blade of a small turbofan engine, where geometry and aerodynamic data was available, was analyzed for its structural behavior in the proposed mission envelope, where the engine turbine is subjected to high thermal, inertial and aerodynamic loads. FE linear stress analysis was carried out on the turbine blade. The results revealed the upper limit of UTS for the blade. Based on the limiting factor, high performance alloys were selected from the literature. The two most recommended alloy categories for gas turbine blades are NIMONIC and INCONEL from where total of 21 types of INCONEL alloys and 12 of NIMONIC alloys, available on on commercial bases, were analyzed individually to meet the INCONEL alloys for further analysis. On the basis of stress-strain behavior of finalized alloys, the FE restriction of UFOS of 1.33 and yield strength. Final selection is made keeping in view other factors like manufacturability and workability in due consideration. (author)

  17. Selection of High Performance Alloy for Gas Turbine Blade Using Multiphysics Analysis

    Directory of Open Access Journals (Sweden)

    H Khawaja

    2016-09-01

    Full Text Available With the extensive increase in the utilization of energy resources in the modern era, the need of energy extraction from various resources has pronounced in recent years. Thus comprehensive efforts have been made around the globe in the technological development of turbo machines where means of energy extraction is energized fluids. This development led the aviation industry to power boost due to better performing engines. Meanwhile, the structural conformability requirements relative to the functional requirements have also increased with the advent of newer, better performing materials. Thus there is a need to study the material behavior and its usage with the idea of selecting the best possible material for its application. In this work a gas turbine blade of a small turbofan engine, where geometry and aerodynamic data was available, was analyzed for its structural behavior in the proposed mission envelope, where the engine turbine is subjected to high thermal, inertial and aerodynamic loads. Multiphysics Finite Element (FE linear stress analysis was carried out on the turbine blade. The results revealed the upper limit of Ultimate Tensile Strength (UTS for the blade. Based on the limiting factor, high performance alloys were selected from the literature. The two most recommended alloy categories for gas turbine blades are NIMONIC and INCONEL from where total of 21 types of INCONEL alloys and 12 of NIMONIC alloys, available on commercial bases, were analyzed individually to meet the structural requirements. After applying selection criteria, four alloys were finalized from NIMONIC and INCONEL alloys for further analysis. On the basis of stress-strain behavior of finalized alloys, the Multiphysics FE nonlinear stress analysis was then carried out for the selection of the individual alloy by imposing a restriction of Ultimate Factor of Safety (UFOS of 1.33 and yield strength. Final selection is made keeping in view other factors

  18. Condensation phenomena in a turbine blade passage

    International Nuclear Information System (INIS)

    Skillings, S.A.

    1989-02-01

    The mechanisms associated with the formation and growth of water droplets in the large low-pressure (LP) turbines used for electrical power generation are poorly understood and recent measurements have indicated that an unusually high loss is associated with the initial nucleation of these droplets. In order to gain an insight into the phenomena which arise in the turbine situation, some experiments were performed to investigate the behaviour of condensing steam flows in a blade passage. This study has revealed the fundamental significance of droplet nucleation in modifying the single-phase flow structure and results are presented which show the change in shock wave pattern when inlet superheat and outlet Mach number are varied. The trailing-edge shock wave structure appears considerably more robust towards variation of inlet superheat than purely one-dimensional considerations may suggest and the inadequacies of adopting a one-dimensional theory to analyse multi-dimensional condensing flows are demonstrated. Over a certain range of outlet Mach numbers an oscillating shock wave will establish in the throat region of the blade passage and this has been shown to interact strongly with droplet nucleation, resulting in a considerably increased mean droplet size. The possible implications of these results for turbine performance are also discussed. (author)

  19. Dislocation movement and hysteresis in Maraging blades

    Energy Technology Data Exchange (ETDEWEB)

    Di Cintio, Arianna; Ascione, Maria; De Salvo, Riccardo [LIGO Laboratory, California Institute of Technology, MS 18-34, 1200 E.California Blvd., Pasadena, CA, 91125 (United States); Marchesoni, Fabio [INFN-VIRGO Project Dipartimento di Fisica, Universita' di Camerino, I-62032 Camerino (Italy); Bhawal, Abhik, E-mail: desalvo@ligo.caltech.ed [Arcadia High School, Arcadia, CA (United States)

    2009-10-21

    All seismic isolation systems developed for gravitational-wave interferometric detectors, such as LIGO, Virgo and TAMA, make use of Maraging steel blades. The dissipation properties of these blades have been studied at low frequencies, by using a geometric anti-spring (GAS) filter, which allowed the exploration of resonant frequencies below 100 mHz. At this frequency an anomalous transfer function was observed in the GAS filter: this is one of several motivations for this work. The many unexpected effects observed and measured are explainable by the collective movement of dislocations inside the material described with the statistic of self-organised criticality. At low frequencies, below 200 mHz, the dissipation mechanism can subtract elasticity from the system even leading to sudden collapse. While Young's modulus is weaker, excess dissipation is observed. At higher frequencies the applied stress is probably too fast to allow the full growth of dislocation avalanches, and less losses are observed, thus explaining the higher Q-factor in this frequency range. The domino effect that leads to the release of entangled dislocations allows the understanding of the random walk of the Virgo and TAMA inverted pendula, the anomalous GAS filter transfer function as well as the loss of predictability of the ring-down decay in the LIGO seismic attenuation system inverted pendula.

  20. Preliminary Aerodynamic Investigation of Fan Rotor Blade Morphing

    Science.gov (United States)

    Tweedt, Daniel L.

    2012-01-01

    Various new technologies currently under development may enable controlled blade shape variability, or so-called blade morphing, to be practically employed in aircraft engine fans and compressors in the foreseeable future. The current study is a relatively brief, preliminary computational fluid dynamics investigation aimed at partially demonstrating and quantifying the aerodynamic potential of fan rotor blade morphing. The investigation is intended to provide information useful for near-term planning, as well as aerodynamic solution data sets that can be subsequently analyzed using advanced acoustic diagnostic tools, for the purpose of making fan noise comparisons. Two existing fan system models serve as baselines for the investigation: the Advanced Ducted Propulsor fan with a design tip speed of 806 ft/sec and a pressure ratio of 1.294, and the Source Diagnostic Test fan with a design tip speed of 1215 ft/sec and a pressure ratio of 1.470. Both are 22-in. sub-scale, low-noise research fan/nacelle models that have undergone extensive experimental testing in the 9- by 15-foot Low Speed Wind Tunnel at the NASA Glenn Research Center. The study, restricted to fan rotor blade morphing only, involves a fairly simple blade morphing technique. Specifically, spanwise-linear variations in rotor blade-section setting angle are applied to alter the blade shape; that is, the blade is linearly retwisted from hub to tip. Aerodynamic performance comparisons are made between morphed-blade and corresponding baseline configurations on the basis of equal fan system thrust, where rotor rotational speed for the morphed-blade fan is varied to change the thrust level for that configuration. The results of the investigation confirm that rotor blade morphing could be a useful technology, with the potential to enable significant improvements in fan aerodynamic performance. Even though the study is very limited in scope and confined to simple geometric perturbations of two existing fan

  1. Parametric Investigation of the Effect of Hub Pitching Moment on Blade Vortex Interaction (BVI) Noise of an Isolated Rotor

    Science.gov (United States)

    Malpica, Carlos; Greenwood, Eric; Sim, Ben

    2016-01-01

    At the most fundamental level, main rotor loading noise is caused by the harmonically-varying aerodynamic loads (acoustic pressures) exerted by the rotating blades on the air. Rotorcraft main rotor noise is therefore, in principle, a function of rotor control inputs, and thus the forces and moments required to achieve steady, or "trim", flight equilibrium. In certain flight conditions, the ensuing aerodynamic loading on the rotor(s) can result in highly obtrusive harmonic noise. The effect of the propulsive force, or X-force, on Blade-Vortex Interaction (BVI) noise is well documented. This paper presents an acoustics parametric sensitivity analysis of the effect of varying rotor aerodynamic pitch hub trim moments on BVI noise radiated by an S-70 helicopter main rotor. Results show that changing the hub pitching moment for an isolated rotor, trimmed in nominal 80 knot, 6 and 12 deg descent, flight conditions, alters the miss distance between the blades and the vortex in ways that have varied and noticeable effects on the BVI radiated-noise directionality. Peak BVI noise level is however not significantly altered. The application of hub pitching moment allows the attitude of the fuselage to be controlled; for example, to compensate for the uncomfortable change in fuselage pitch attitude introduced by a fuselage-mounted X-force controller.

  2. 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...

  3. Aerodynamic load control strategy of wind turbine in microgrid

    Science.gov (United States)

    Wang, Xiangming; Liu, Heshun; Chen, Yanfei

    2017-12-01

    A control strategy is proposed in the paper to optimize the aerodynamic load of the wind turbine in micro-grid. In grid-connection mode, the wind turbine adopts a new individual variable pitch control strategy. The pitch angle of the blade is rapidly given by the controller, and the pitch angle of each blade is fine tuned by the weight coefficient distributor. In islanding mode, according to the requirements of energy storage system, a given power tracking control method based on fuzzy PID control is proposed. Simulation result shows that this control strategy can effectively improve the axial aerodynamic load of the blade under rated wind speed in grid-connection mode, and ensure the smooth operation of the micro-grid in islanding mode.

  4. A new dynamic model of rotor-blade systems

    Science.gov (United States)

    Ma, Hui; Lu, Yang; Wu, Zhiyuan; Tai, Xingyu; Li, Hui; Wen, Bangchun

    2015-11-01

    A new dynamic model of rotor-blade systems is developed in this paper considering the lateral and torsional deformations of the shaft, gyroscopic effects of the rotor which consists of shaft and disk, and the centrifugal stiffening, spin softening and Coriolis force of the blades. In this model, the rotating flexible blades are represented by Timoshenko beams. The shaft and rigid disk are described by multiple lumped mass points (LMPs), and these points are connected by massless springs which have both lateral and torsional stiffness. LMPs are represented by the corresponding masses and mass moments of inertia in lateral and rotational directions, where each point has five degrees of freedom (dofs) excluding axial dof. Equations of motion of the rotor-blade system are derived using Hamilton's principle in conjunction with the assumed modes method to describe blade deformation. The proposed model is compared with both finite element (FE) model and real experiments. The proposed model is first validated by comparing the model natural frequencies and vibration responses with those obtained from an FE model. A further verification of the model is then performed by comparing the model natural frequencies at zero rotational speed with those obtained from experimental studies. The results shown a good agreement between the model predicted system characteristics and those obtained from the FE model and experimental tests. Moreover, the following interesting phenomena have been revealed from the new model based analysis: The torsional natural frequency of the system decreases with the increase of rotational speed, and the frequency veering phenomenon has been observed at high rotational speed; The complicated coupling modes, such as the blade-blade coupling mode (BB), the coupling mode between the rotor lateral vibration and blade bending (RBL), and the coupling mode between the rotor torsional vibration and blade bending (RBT), have also been observed when the number of

  5. Manufacturing a 9-Meter Thermoplastic Composite Wind Turbine Blade: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Robynne [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Snowberg, David R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Berry, Derek S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Beach, Ryan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rooney, Samantha A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Swan, Dana [Arkema Inc.

    2017-12-06

    Currently, wind turbine blades are manufactured from a combination of glass and/or carbon fiber composite materials with a thermoset resin such as epoxy, which requires energy-intensive and expensive heating processes to cure. Newly developed in-situ polymerizing thermoplastic resin systems for composite wind turbine blades polymerize at room temperature, eliminating the heating process and significantly reducing the blade manufacturing cycle time and embodied energy, which in turn reduces costs. Thermoplastic materials can also be thermally welded, eliminating the need for adhesive bonds between blade components and increasing the overall strength and reliability of the blades. As well, thermoplastic materials enable end-of-life blade recycling by reheating and decomposing the materials, which is a limitation of existing blade technology. This paper presents a manufacturing demonstration for a 9-m-long thermoplastic composite wind turbine blade. This blade was constructed in the Composites Manufacturing Education and Technology facility at the National Wind Technology Center at the National Renewable Energy Laboratory (NREL) using a vacuum-assisted resin transfer molding process. Johns Manville fiberglass and an Arkema thermoplastic resin called Elium were used. Additional materials included Armacell-recycled polyethylene terephthalate foam from Creative Foam and low-cost carbon- fiber pultruded spar caps (manufactured in collaboration with NREL, Oak Ridge National Laboratory, Huntsman, Strongwell, and Chomarat). This paper highlights the development of the thermoplastic resin formulations, including an additive designed to control the peak exothermic temperatures. Infusion and cure times of less than 3 hours are also demonstrated, highlighting the efficiency and energy savings associated with manufacturing thermoplastic composite blades.

  6. Definition of a 5MW/61.5m wind turbine blade reference model.

    Energy Technology Data Exchange (ETDEWEB)

    Resor, Brian Ray

    2013-04-01

    A basic structural concept of the blade design that is associated with the frequently utilized %E2%80%9CNREL offshore 5-MW baseline wind turbine%E2%80%9D is needed for studies involving blade structural design and blade structural design tools. The blade structural design documented in this report represents a concept that meets basic design criteria set forth by IEC standards for the onshore turbine. The design documented in this report is not a fully vetted blade design which is ready for manufacture. The intent of the structural concept described by this report is to provide a good starting point for more detailed and targeted investigations such as blade design optimization, blade design tool verification, blade materials and structures investigations, and blade design standards evaluation. This report documents the information used to create the current model as well as the analyses used to verify that the blade structural performance meets reasonable blade design criteria.

  7. 3D pressure imaging of an aircraft propeller blade-tip flow by phase-locked stereoscopic PIV

    Energy Technology Data Exchange (ETDEWEB)

    Ragni, D.; Oudheusden, B.W. van; Scarano, F. [Delft University of Technology, Faculty of Aerospace Engineering, Delft (Netherlands)

    2012-02-15

    The flow field at the tip region of a scaled DHC Beaver aircraft propeller, running at transonic speed, has been investigated by means of a multi-plane stereoscopic particle image velocimetry setup. Velocity fields, phase-locked with the blade rotational motion, are acquired across several planes perpendicular to the blade axis and merged to form a 3D measurement volume. Transonic conditions have been reached at the tip region, with a revolution frequency of 19,800 rpm and a relative free-stream Mach number of 0.73 at the tip. The pressure field and the surface pressure distribution are inferred from the 3D velocity data through integration of the momentum Navier-Stokes equation in differential form, allowing for the simultaneous flow visualization and the aerodynamic loads computation, with respect to a reference frame moving with the blade. The momentum and pressure data are further integrated by means of a contour-approach to yield the aerodynamic sectional force components as well as the blade torsional moment. A steady Reynolds averaged Navier-Stokes numerical simulation of the entire propeller model has been used for comparison to the measurement data. (orig.)

  8. 3D pressure imaging of an aircraft propeller blade-tip flow by phase-locked stereoscopic PIV

    Science.gov (United States)

    Ragni, D.; van Oudheusden, B. W.; Scarano, F.

    2012-02-01

    The flow field at the tip region of a scaled DHC Beaver aircraft propeller, running at transonic speed, has been investigated by means of a multi-plane stereoscopic particle image velocimetry setup. Velocity fields, phase-locked with the blade rotational motion, are acquired across several planes perpendicular to the blade axis and merged to form a 3D measurement volume. Transonic conditions have been reached at the tip region, with a revolution frequency of 19,800 rpm and a relative free-stream Mach number of 0.73 at the tip. The pressure field and the surface pressure distribution are inferred from the 3D velocity data through integration of the momentum Navier-Stokes equation in differential form, allowing for the simultaneous flow visualization and the aerodynamic loads computation, with respect to a reference frame moving with the blade. The momentum and pressure data are further integrated by means of a contour-approach to yield the aerodynamic sectional force components as well as the blade torsional moment. A steady Reynolds averaged Navier-Stokes numerical simulation of the entire propeller model has been used for comparison to the measurement data.

  9. An Innovative Technique for Evaluating the Integrity and Durability of Wind Turbine Blade Composites

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL; Ren, Fei [ORNL

    2010-09-01

    Wind turbine blades are subjected to complex multiaxial stress states during operation. A review of the literature suggests that mixed mode fracture toughness can be significantly less than that of the tensile opening mode (Mode I), implying that fracture failure can occur at a much lower load capacity if the structure is subject to mixed-mode loading. Thus, it will be necessary to identify the mechanisms that might lead to failure in blade materials under mixed-mode loading conditions. Meanwhile, wind turbine blades are typically fabricated from fiber reinforced polymeric materials, e.g. fiber glass composites. Due to the large degree of anisotropy in mechanical properties that is usually associated with laminates, the fracture behavior of these composite materials is likely to be strongly dependent on the loading conditions. This may further strengthen the need to study the effect of mixed-mode loading on the integrity and durability of the wind turbine blade composites. To quantify the fracture behavior of composite structures under mixed mode loading conditions, particularly under combined Mode I (flexural or normal tensile stress) and Mode III (torsional shear stress) loading, a new testing technique is proposed based on the spiral notch torsion test (SNTT). As a 2002 R&D 100 Award winner, SNTT is a novel fracture testing technology. SNTT has many advantages over conventional fracture toughness methods and has been used to determine fracture toughness values on a wide spectrum of materials. The current project is the first attempt to utilize SNTT on polymeric and polymer-based composite materials. It is expected that mixed-mode failure mechanisms of wind turbine blades induced by typical in-service loading conditions, such as delamination, matrix cracking, fiber pull-out and fracture, can be effectively and economically investigated by using this methodology. This project consists of two phases. The Phase I (FY2010) effort includes (1) preparation of testing

  10. Fractographic study of epoxy fractured under mode I loading and mixed mode I/III loading

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Fei [ORNL; Wang, Jy-An John [ORNL; Bertelsen, Williams D. [Gougeon Brothers, Inc.

    2011-01-01

    Fiber reinforced polymeric composite materials are widely used in structural components such as wind turbine blades, which are typically subject to complicated loading conditions. Thus, material response under mixed mode loading is of great significance to the reliability of these structures. Epoxy is a thermosetting polymer that is currently used in manufacturing wind turbine blades. The fracture behavior of epoxy is relevant to the mechanical integrity of the wind turbine composite materials. In this study, a novel fracture testing methodology, the spiral notch torsion test (SNTT), was applied to study the fracture behavior of an epoxy material. SNTT samples were tested using either monotonic loading or cyclic loading, while both mode I and mixed mode I/III loading conditions were used. Fractographic examination indicated the epoxy samples included in this study were prone to mode I failure even when the samples were subject to mixed mode loading. Different fatigue precracks were observed on mode I and mixed mode samples, i.e. precracks appeared as a uniform band under mode I loading, and a semi-ellipse under mixed mode loading. Fracture toughness was also estimated using quantitative fractography.

  11. 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

  12. Considering the function of Middle Palaeolithic blade technologies through an examination of experimental blade edge angles

    DEFF Research Database (Denmark)

    Hoggard, Christian Steven

    2017-01-01

    to assess the degree of variance between both blade strategies. Analyses demonstrate considerable difference in both the distribution of edge angles produced, and the mean edge angle values observed. Through the analytical framework it can be demonstrated that both blade production methods would have...... manufacturing techniques. Using an experimental dataset, this article investigates differences in the function of both strategies through a consideration of their edge angle, an important functional attribute of lithic artefacts. A null hypothesis of ‘no difference’ was examined through a statistical framework...... provided distinct differences for past hominin populations, with respect to their microfracturing properties and attrition rate. However, when reviewed against other edge angle analyses, against a functional backdrop, their edge angle in isolation cannot explain their appearance and subsequent use. Further...

  13. Determination of unsteady loads on a DU96W180 airfoil with actuated flap using particle image velocimetry

    NARCIS (Netherlands)

    Lindeboom, R.C.J.; Sterenborg, J.J.H.M.; Simao Ferreira, C.J.

    2010-01-01

    The unsteady flow conditions experienced by wind turbine blades lead to fatigue loads due to gusts, that increase the cost of energy. The decrease of the impact of these unsteady loads will most certainly lead to a decrease of the cost of energy. In order to alleviate unsteady loads the Smart Rotor

  14. Investigation on pitch system loads by means of an integral multi body simulation approach

    Science.gov (United States)

    Berroth, J.; Jacobs, G.; Kroll, T.; Schelenz, R.

    2016-09-01

    In modern horizontal axis wind turbines the rotor blades are adjusted by three individual pitch systems to control power output. The pitch system consists of either a hydraulic or an electrical actuator, the blade bearing, the rotor blade itself and the control. In case of an electrical drive a gearbox is used to transmit the high torques that are required for blade pitch angle adjustment. In this contribution a new integral multi body simulation approach is presented that enables detailed assessment of dynamic pitch system loads. The simulation results presented are compared and evaluated with measurement data of a 2 MW-class reference wind turbine. Major focus of this contribution is on the assessment of non linear tooth contact behaviour incorporating tooth backlash for the single gear stages and the impact on dynamic pitch system loads.

  15. 14 CFR 35.35 - Centrifugal load tests.

    Science.gov (United States)

    2010-01-01

    ... propeller could be sensitive to environmental degradation in service, this must be considered. This section does not apply to fixed-pitch wood or fixed-pitch metal propellers of conventional design. (a) The hub... example, spinners, de-icing equipment, and blade erosion shields) must be subjected to a load equivalent...

  16. Turbine blade with spar and shell

    Science.gov (United States)

    Davies, Daniel O [Palm City, FL; Peterson, Ross H [Loxahatchee, FL

    2012-04-24

    A turbine blade with a spar and shell construction in which the spar and the shell are both secured within two platform halves. The spar and the shell each include outward extending ledges on the bottom ends that fit within grooves formed on the inner sides of the platform halves to secure the spar and the shell against radial movement when the two platform halves are joined. The shell is also secured to the spar by hooks extending from the shell that slide into grooves formed on the outer surface of the spar. The hooks form a serpentine flow cooling passage between the shell and the spar. The spar includes cooling holes on the lower end in the leading edge region to discharge cooling air supplied through the platform root and into the leading edge cooling channel.

  17. Characterization of a Viking Blade Fabricated by Traditional Forging Techniques

    Science.gov (United States)

    Vo, H.; Frazer, D.; Bailey, N.; Traylor, R.; Austin, J.; Pringle, J.; Bickel, J.; Connick, R.; Connick, W.; Hosemann, P.

    2016-12-01

    A team of students from the University of California, Berkeley, participated in a blade-smithing competition hosted by the Minerals, Metals, and Materials Society at the TMS 2015 144th annual meeting and exhibition. Motivated by ancient forging methods, the UC Berkeley team chose to fabricate our blade from historical smithing techniques utilizing naturally-occurring deposits of iron ore. This approach resulted in receiving the "Best Example of a Traditional Blade Process/Ore Smelting Technique" award for our blade named "Berkelium." First, iron-enriched sand was collected from local beaches. Magnetite (Fe3O4) was then extracted from the sand and smelted into individual high- and low-carbon steel ingots. Layers of high- and low-carbon steels were forge-welded together, predominantly by hand, to form a composite material. Optical microscopy, energy dispersive spectroscopy, and Vickers hardness mechanical testing were conducted at different stages throughout the blade-making process to evaluate the microstructure and hardness evolution during formation. It was found that the pre-heat-treated blade microstructure was composed of ferrite and pearlite, and contained many nonmetallic inclusions. A final heat treatment was performed, which caused the average hardness of the blade edge to increase by more than a factor of two, indicating a martensitic transformation.

  18. Water droplet erosion of stainless steel steam turbine blades

    Science.gov (United States)

    Kirols, H. S.; Kevorkov, D.; Uihlein, A.; Medraj, M.

    2017-08-01

    Steam turbine blades are highly subjected to water droplet erosion (WDE) caused by high energy impingement of liquid water droplets. However, most of the published research on this wear phenomenon is performed on laboratory test rigs, instead of addressing WDE of actual steam turbine blades. In this work, the progression of erosion on the surface of ex-service low pressure steam turbine blades was investigated using scanning electron microscopy. The erosion appearance and mechanisms are compared with laboratory test rig results that are carried out using a rotating disk rig according to ASTM G73 standard. Initial and advanced erosion stages could be observed on the steam turbine blades. Similar to the WDE rig coupons, initial pits and cracks were preceded by blade surface roughening through the formation of asperities and depressions. In addition, it was also observed that the twist angle of the turbine blade around its diagonal, is an important parameter that influences its WDE. Twist angle has an effect on: impact angle, erosion appearance, impact speed, and the affected area. Furthermore, according to the current experimental results, multi-ray rig erosion test results are considered the closest simulation to the actual ex-service blade in terms of damage appearance.

  19. The Concept of Segmented Wind Turbine Blades: A Review

    Directory of Open Access Journals (Sweden)

    Mathijs Peeters

    2017-07-01

    Full Text Available There is a trend to increase the length of wind turbine blades in an effort to reduce the cost of energy (COE. This causes manufacturing and transportation issues, which have given rise to the concept of segmented wind turbine blades. In this concept, multiple segments can be transported separately. While this idea is not new, it has recently gained renewed interest. In this review paper, the concept of wind turbine blade segmentation and related literature is discussed. The motivation for dividing blades into segments is explained, and the cost of energy is considered to obtain requirements for such blades. An overview of possible implementations is provided, considering the split location and orientation, as well as the type of joint to be used. Many implementations draw from experience with similar joints such as the joint at the blade root, hub and root extenders and joints used in rotor tips and glider wings. Adhesive bonds are expected to provide structural and economic efficiency, but in-field assembly poses a big issue. Prototype segmented blades using T-bolt joints, studs and spar bridge concepts have proven successful, as well as aerodynamically-shaped root and hub extenders.

  20. Study of Pumping Capacity of Pitched Blade Impellers

    Directory of Open Access Journals (Sweden)

    I. Fořt

    2002-01-01

    Full Text Available A study was made of the pumping capacity of pitched blade impellers in a cylindrical pilot plant vessel with four standard radial baffles at the wall under a turbulent regime of flow. The pumping capacity was calculated from the radial profile of the axial flow, under the assumption of axial symmetry of the discharge flow. The mean velocity was measured using laser Doppler anemometry in a transparent vessel of diameter T = 400 mm, provided with a standard dished bottom. Three and six blade pitched blade impellers (the pitch angle varied within the interval a Îá24°; 45°ń of impeller/vessel diameter ratio D/T = 0.36, as well as a three blade pitched blade impeller with folded blades of the same diameter, were tested. The calculated results were compared with the results of experiments mentioned in the literature, above all in cylindrical vessels with a flat bottom. Both arrangements of the agitated system were described by the impeller energetic efficiency, i.e, a criterion including in dimensionless form both the impeller energy consumption (impeller power input and the impeller pumping effect (impeller pumping capacity. It follows from the results obtained with various geometrical configurations that the energetic efficiency of pitched blade impellers is significantly lower for configurations suitable for mixing solid-liquid suspensions (low impeller off bottom clearances than for blending miscible liquids in mixing (higher impeller off bottom clearances.

  1. Helicopter blades running elevation measurement using omnidirectional vision

    Directory of Open Access Journals (Sweden)

    Chengtao CAI

    2017-12-01

    Full Text Available Omnidirectional dynamic space parameters of high-speed rotating helicopter blades are precise 3D vector description of the blades. In particular, the elevation difference is directly related to the aerodynamic performance and maneuverability of the helicopter. The state of the art detection techniques based on optics and common vision have several drawbacks, such as high demands on devices but poor extensibility, limited measurement range and fixed measurement position. In this paper, a novel approach of helicopter blades running elevation measurement is proposed based on omnidirectional vision. With the advantages of panoramic visual imaging integration, 360° field of view and rotation in-variance, high-resolution images of all rotating blades positions are obtained at one time. By studying the non-linear calibration and calculation model of omnidirectional vision system, aiming at solving the problem of inaccurate visual space mapping model, the omnidirectional and full-scale measurement of the elevation difference are finalized. Experiments are carried out on our multifunctional simulation blades test system and the practical blades test tower, respectively. The experimental results demonstrate the effectiveness of the proposed method and show that the proposed method can considerably reduce the complexity of measurement. Keywords: Full-scale measurement, Helicopter blades elevation, Non-linear calibration, Omnidirectional vision, Unified sphere model

  2. Shikarpur lithic assemblage: New questions regarding Rohri chert blade production

    Directory of Open Access Journals (Sweden)

    Charusmita Gadekar

    2014-03-01

    Full Text Available Recent excavations at Shikarpur, a fortified Harappan site situated near the Gulf of Kuchchh in Gujarat, Western India, brought to light a large collection of Rohri chert blades.  Chert found in the Rohri hill near Sukkur in Sindh, central Pakistan is distinctive and easily identifiable. The wide distribution of standardized Rohri chert blades is often regarded as a testimony to the Harappan efficiency in long distance trade and craft production.  The possibility of localized production of Rohri chert blades in Gujarat is often negated due to the constraints of raw-material availability.  The absence of Rohri chert working debitage from most of the sites in Gujarat, has lent support to this position. The Shikarpur Rohri blade assemblage however incorporates more than 650 blades, a large fluted blade-core and a few Rohri chert debitage.  These have led the excavators to suggest that some of the blades found at Shikarpur were locally produced from raw materials brought to the site from the Rohri hills.  Typo-technological features of the Rohri chert assemblage from Shikarpur have been analysed in this background. These along with metrical features of the assemblage are compared with Rohri chert assemblages from other major Harappan sites in the region to check the validity of the proposed ‘limited local production’.

  3. Investigating dynamic stall, 3-D and rotational effects on wind turbine blades by means of an unsteady quasi-3D Navier-Stokes solver

    Energy Technology Data Exchange (ETDEWEB)

    Chaviaropoulos, P.K. [CRES-Center for Renewable Energy Sources, Pikermi Attiki (Greece)

    1997-08-01

    The blade element codes provide surprisingly accurate predictions of the aerodynamic loads provided that they are `fed` with proper lift and drag - incidence curves for the profiles mounted on the rotor blades. The evident question is how one can obtain such data. It is common experience that the use of the mostly available steady two-dimensional profile data may lead to serious discrepancies between measured and simulated loads. Although several correction techniques have been proposed as a remedy during the last years, from simplified dynamic stall models suitably tuned for wind turbines to 3-D correction schemes for profile data, the problem is by no means over-passed. Especially for the three-dimensional effects it seems that part of the difficulty is due to our limited understanding of the physical mechanism which is responsible for the extra loading of the inner part of the blades. Recognizing the importance of the above aspects two relevant Joule projects have been launched, the concluded `Dynamic Stall and 3-D Effects` JOU2-CT93-0345 and the ongoing `VISCWIND` JOR3-CT95-0007 project. Part of the activities in the first and all the activities in the second project are devoted to the identification and quantification of the dynamic stall and three-dimensional effects experienced by the wind turbine blades using Navier-Stokes computations. The contribution of CRES in these two projects is briefly presented in this paper. (EG)

  4. 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.

  5. Structural damage and chemical contaminants on reprocessed arthroscopic shaver blades.

    Science.gov (United States)

    Kobayashi, Masahiko; Nakagawa, Yasuaki; Okamoto, Yukihiro; Nakamura, Shinichiro; Nakamura, Takashi

    2009-02-01

    In response to socioeconomic pressure to cut budgets in medicine, single-use surgical instruments are often reprocessed despite potential biological hazard. To evaluate the quality and contaminants of reprocessed shaver blades. Reprocessed shaver blades have mechanical damage and chemical contamination. Controlled laboratory study. Seven blades and 3 abraders were reprocessed 1 time or 3 times and then were assessed. In the first part of the study, structural damage on the blades after 3 reprocessings was compared to that after 1 reprocessing using optical microscopy. In the second part, surface damage was observed using optical microscopy and scanning electron microscopy; elemental and chemical analyses of contaminants found by the microscopy were performed using scanning electron microscopy/energy dispersive x-ray spectroscopy, scanning Auger microscopy, and Fourier transform infrared spectroscopy. Optical microscopic examination revealed abrasion on the surface of the inner blade and cracks on the inner tube after 1 reprocessing. These changes were more evident after 3 reprocessings. Scanning electron microscopy/energy dispersive x-ray spectroscopy of the inner cutter of the blade reprocessed once showed contaminants containing calcium, carbon, oxygen, and silicon, and Fourier transform infrared spectroscopy demonstrated biological protein consisting mainly of collagen, some type of salts, and polycarbonate used in plastic molding. Scanning electron microscopy/energy dispersive x-ray spectroscopy of the inner cutter of the reprocessed abrader revealed contaminants containing carbon, calcium, phosphorous, and oxygen, and Fourier transform infrared spectroscopy showed H2O, hydroxyapatite, and hydroxyl proteins. Scanning Auger microscopy showed that the tin-nickel plating on the moving blade and abrader was missing in some locations. This is the first study to evaluate both mechanical damage and chemical contaminants containing collagen, hydroxyapatite, and salts

  6. Acoustic emission testing and estimation of the damage of wind turbine blades; Examen par emission acoustique et evaluation de l'endommagement de pales d'eolienne

    Energy Technology Data Exchange (ETDEWEB)

    Dutton, A.G.; Blanch, M.J. [Energy Research Unit, CLRC Rutherford Appleton Lab. (United Kingdom); Vionis, P; Lekou, D. [Centre for Rnewable Energy Sources (CRES) (Greece); Van Delft, D.R.V.; Joosse, P. [Delft Univ. of Technology, Knowledge Centre WMC (Netherlands); Anastassopoulos, A.; Kouroussis, D. [Envirocoustics Abee (Greece); Kossivas, T. [Geobiologiki S.A. (Greece); Philippidis, T. [Patras Univ. (Greece); Fernando, G.; Doyle, C. [Cranfield Univ. (United Kingdom); Proust, A. [Euro Physical Acoustics S.A. (France)

    2007-05-15

    Wind turbines experience long term fluctuating variable amplitude fatigue loads with occasional large amplitude stochastic peak loads. A methodology for wind turbine blade monitoring using acoustic emission (AE) detection of damage processes in the structure has been developed by the AEGIS consortium, supported by the European Commission. Characteristic results are presented of AE activity during peak loading events and fatigue blade tests to failure in the laboratory. The results presented indicate the kind of results, which could be obtained from monitoring in-service machines. In particular, a dedicated pattern recognition software has been developed which could identify differences from turbine to turbine and help target preventative maintenance. Validation of the software from laboratory tests on blades is presented. (authors)

  7. Estimation of water flow added damping on a propeller turbine blade using numerical simulations

    Science.gov (United States)

    Gauthier, Jean-Philippe; Gosselin, Frederick P.; Etienne, Stephane

    2015-11-01

    In the province of Quebec, Canada, around 99% of the electricity generation is through hydropower. Alternative energy sources, in particular wind, are however becoming increasingly harnessed. Since electrical energy cannot be stored in appreciable amounts, generation from hydroelectric turbines must constantly be adjusted to compensate for fluctuations in wind power. This leads to more frequent turbine stops and restarts, during which the loads due to water flowing around the blades are known to cause high mechanical stresses thus reduce fatigue life. Yet, fluid flows also have desirable damping effects, a phenomenon which received little scientific attention in the case of water turbines. A method to estimate this so-called fluid flow added damping is here presented. It is based on computational structural/fluid dynamics (CSD/CFD) and is essentially non-coupled in the sense that bidirectional coupling of the CSD and CFD codes is not required. The approach used is to prescribe oscillatory modal motion of the structural boundary in the flow simulation in order to extract damping from the resulting fluid load. The method has been validated using experimental data available for a simplified test case then applied to a propeller turbine blade.

  8. Defect distribution and reliability assessment of wind turbine blades

    DEFF Research Database (Denmark)

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

    2011-01-01

    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...... with and without defects in terms of delaminations. The reliability of the blade decreases when defects are included. However, the distribution of the defects influences how much the reliability is decreased. It is also shown how non-destructive inspection (NDI) after production can be used to update...... the reliability for the wind turbine blade using Bayesian statistics....

  9. Results of the benchmark for blade structural models, part A

    DEFF Research Database (Denmark)

    Lekou, D.J.; Chortis, D.; Belen Fariñas, A.

    2013-01-01

    Task 2.2 of the InnWind.Eu project. The benchmark is based on the reference wind turbine and the reference blade provided by DTU [1]. "Structural Concept developers/modelers" of WP2 were provided with the necessary input for a comparison numerical simulation run, upon definition of the reference blade......A benchmark on structural design methods for blades was performed within the InnWind.Eu project under WP2 “Lightweight Rotor” Task 2.2 “Lightweight structural design”. The present document is describes the results of the comparison simulation runs that were performed by the partners involved within...

  10. Wind Turbine Blade Deflection Sensing System Based on UWB Technology

    DEFF Research Database (Denmark)

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

    2016-01-01

    A microwave sensing system for estimating deflection of a wind turbine blade is presented. The system measures distances at two ultrawideband (UWB) wireless links between one antenna at the tip and two antennas at the root of the blade, which allows for determination of the tip position...... by triangulation. An experimental setup with corner reflector antenna mounted at the tip and horn antennas at the root of a 37.3 m long blade is described. Analyzing the data from the experiment, special attention is given to the propagation aspects of the UWB links, with focus on the multipath effects caused...

  11. Modal Analysis for Crack Detection in Small Wind Turbine Blades

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Skov, Jonas falk; Dickow, Kristoffer Ahrens

    2013-01-01

    The aim of the present paper is to evaluate structural health monitoring (SHM) techniques based on modal analysis for crack detection in small wind turbine blades. A finite element (FE) model calibrated to measured modal parameters will be introduced to cracks with different sizes along one edge...... of the blade. Changes in modal parameters from the FE model are compared with data obtained from experimental tests. These comparisons will be used to validate the FE model and subsequently discuss the usability of SHM techniques based on modal parameters for condition monitoring of wind turbine blades....

  12. Coupling analysis of wind turbine blades based on aeroelastics and aerodynsmics

    DEFF Research Database (Denmark)

    Wang, Xudong; Chen, Jin; Zhang, Shigiang

    2010-01-01

    The structural dynamic equations of blades were constructed for blades of wind turbines. The vibration velocity of blades and the relative flow velocity were calculated using the structural dynamics model. Based on the BEM (Blade Element Momentum) theory and traditional areodynamics, the coupling...

  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

    The deflection of a wind turbine blade can be monitored with an ultra-wideband (UWB) deflection sensing system which consists of one transmitting antenna at the blade tip and two receiving antennas at the blade root. The blade deflection is calculated by two estimated tip-root antenna distances...

  14. 14 CFR 33.94 - Blade containment and rotor unbalance tests.

    Science.gov (United States)

    2010-01-01

    ... critical compressor or fan blade while operating at maximum permissible r.p.m. The blade failure must occur... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Blade containment and rotor unbalance tests... Blade containment and rotor unbalance tests. (a) Except as provided in paragraph (b) of this section, it...

  15. Component Analysis of Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blades of Different Blade Outlet Angles

    Directory of Open Access Journals (Sweden)

    Yasuyuki Nishi

    2015-01-01

    Full Text Available Single-blade centrifugal impellers for sewage systems undergo both unsteady radial and axial thrusts. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces and determine the generation mechanism behind them. In this study, we conducted component analyses of radial and axial thrusts of closed, single-blade centrifugal pumps with different blade outlet angles by numerical analysis while considering leakage flow. The results revealed the effect of the blade outlet angle on the components of radial and axial thrusts. For increased flow rates, the time-averaged values of the pressure component were similar for all impellers, although its fluctuating components were higher for impellers with larger blade outlet angles. Moreover, the fluctuating inertia component of the impeller with a blade outlet angle of 8° decreased as the flow rate increased, whereas those with 16° and 24° angles increased. Therefore, the radial thrust on the hydraulic part was significantly higher for impellers with high blade outlet angles.

  16. Effect of steady deflections on the aeroelastic stability of a turbine blade

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    2011-01-01

    This paper deals with effects of geometric non-linearities on the aeroelastic stability of a steady-state defl ected blade. Today, wind turbine blades are long and slender structures that can have a considerable steady-state defl ection which affects the dynamic behaviour of the blade. The fl...... apwise blade defl ection causes the edgewise blade motion to couple to torsional blade motion and thereby to the aerodynamics through the angle of attack. The analysis shows that in the worst case for this particular blade, the edgewise damping can be decreased by half. Copyright © 2010 John Wiley & Sons......, Ltd....

  17. Calibration of partial safety factors for wind turbine rotor blades against fatigue failure; Kalibrering af partielle sikkerhedsfaktorer for udmattelse af vindmoellerotorer

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, C.J.; Ronold, K.O.; Thoegersen, M.L.

    2000-08-01

    The report describes a calibration of partial safety factors for wind turbine rotor blades subjected to fatigue loading in flapwise and edgewise bending. While earlier models - developed by the authors - dealt with such calibrations for site-specific individual turbines only, the calibration model applied herein covers an integrated analysis with different turbines on different sites and with different blade materials. The result is an optimized set of partial safety factors, i.e. a set of safety factors that lead to minimum deviation from the target reliability of the achieved reliabilities over the selected scope of turbines, sites and materials. The turbines included in the study cover rated powers of 450-600 kW. The result from the calibration are discussed in relation to the partial safety factors that are given in the Danish codes for design of glass fibre reinforced rotor blades (DS472 and DS456). (au)

  18. Mach number scaling of helicopter rotor blade/vortex interaction noise

    Science.gov (United States)

    Leighton, Kenneth P.; Harris, Wesley L.

    1985-01-01

    A parametric study of model helicopter rotor blade slap due to blade vortex interaction (BVI) was conducted in a 5 by 7.5-foot anechoic wind tunnel using model helicopter rotors with two, three, and four blades. The results were compared with a previously developed Mach number scaling theory. Three- and four-bladed rotor configurations were found to show very good agreement with the Mach number to the sixth power law for all conditions tested. A reduction of conditions for which BVI blade slap is detected was observed for three-bladed rotors when compared to the two-bladed baseline. The advance ratio boundaries of the four-bladed rotor exhibited an angular dependence not present for the two-bladed configuration. The upper limits for the advance ratio boundaries of the four-bladed rotors increased with increasing rotational speed.

  19. CX-100 and TX-100 blade field tests.

    Energy Technology Data Exchange (ETDEWEB)

    Holman, Adam (USDA-Agriculture Research Service, Bushland, TX); Jones, Perry L.; Zayas, Jose R.

    2005-12-01

    In support of the DOE Low Wind Speed Turbine (LWST) program two of the three Micon 65/13M wind turbines at the USDA Agricultural Research Service (ARS) center in Bushland, Texas will be used to test two sets of experimental blades, the CX-100 and TX-100. The blade aerodynamic and structural characterization, meteorological inflow and wind turbine structural response will be monitored with an array of 75 instruments: 33 to characterize the blades, 15 to characterize the inflow, and 27 to characterize the time-varying state of the turbine. For both tests, data will be sampled at a rate of 30 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.

  20. H-Darrieus Wind Turbine with Blade Pitch Control

    Directory of Open Access Journals (Sweden)

    I. Paraschivoiu

    2009-01-01

    Full Text Available A procedure for computing the optimal variation of the blades' pitch angle of an H-Darrieus wind turbine that maximizes its torque at given operational conditions is proposed and presented along with the results obtained on a 7 kW prototype. The CARDAAV code, based on the “Double-Multiple Streamtube” model developed by the first author, is used to determine the performances of the straight-bladed vertical axis wind turbine. This was coupled with a genetic algorithm optimizer. The azimuthal variation of the blades' pitch angle is modeled with an analytical function whose coefficients are used as variables in the optimization process. Two types of variations were considered for the pitch angle: a simple sinusoidal one and one which is more general, relating closely the blades' pitch to the local flow conditions along their circular path. A gain of almost 30% in the annual energy production was obtained with the polynomial optimal pitch control.

  1. Study on visual detection method for wind turbine blade failure

    Science.gov (United States)

    Chen, Jianping; Shen, Zhenteng

    2018-02-01

    Start your abstract here…At present, the non-destructive testing methods of the wind turbine blades has fiber bragg grating, sound emission and vibration detection, but there are all kinds of defects, and the engineering application is difficult. In this regard, three-point slope deviation method, which is a kind of visual inspection method, is proposed for monitoring the running status of wind turbine blade based on the image processing technology. A better blade image can be got through calibration, image splicing, pretreatment and threshold segmentation algorithm. Design of the early warning system to monitor wind turbine blade running condition, recognition rate, stability and impact factors of the method were statistically analysed. The experimental results shown showed that it has highly accurate and good monitoring effect.

  2. 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...... focusing several factors like less weight, less price, higher performance, longer life, ease of processing, and capability of recycling. In the present market scenario, wind industry needs to improve their business for onshore and for off-shore applications demonstrating the new blade designs and stating...... 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....

  3. 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.

  4. Effect of Number of Blades on Performance of Ceiling Fans

    Directory of Open Access Journals (Sweden)

    Adeeb Ehsan

    2015-01-01

    Full Text Available In this paper, the effect of number of blades on ceiling fan performance is discussed. This approach helps to satisfy tradeoff between high air flow (performance and power consumption (energy efficiency. Specifically, variation from two to six blades is considered with nonlinear forward sweep profile. Reynolds Averaged Navier-Stokes (RANS technique is used to model the flow field induced by the ceiling fan inside a generic room. The performance is gauged through response parameters namely volumetric flow rate, mass flow rate, torque and energy efficiency. The results indicate that mass and volumetric flow rates are maximized for six blade configuration and energy efficiency is maximized for two blade configuration. The study indicates the importance of tradeoff between high air flow through ceiling fan and associated energy efficiency.

  5. Methods for testing of geometrical down-scaled rotor blades

    DEFF Research Database (Denmark)

    Branner, Kim; Berring, Peter

    as requirements for experimental facilities are very demanding and furthermore the time for performing the experimental test campaign and the cost are not well suitable for most research projects. This report deals with the advantages, disadvantages and open questions of using down-scaled testing on wind turbine......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. Fatigue test of wind turbine blades was started in the beginning of the 1980s 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. Those methods are presented in [1]. Current experimental test performed on full...

  6. CMC blade with pressurized internal cavity for erosion control

    Science.gov (United States)

    Garcia-Crespo, Andres; Goike, Jerome Walter

    2016-02-02

    A ceramic matrix composite blade for use in a gas turbine engine having an airfoil with leading and trailing edges and pressure and suction side surfaces, a blade shank secured to the lower end of each airfoil, one or more interior fluid cavities within the airfoil having inlet flow passages at the lower end which are in fluid communication with the blade shank, one or more passageways in the blade shank corresponding to each one of the interior fluid cavities and a fluid pump (or compressor) that provides pressurized fluid (nominally cool, dry air) to each one of the interior fluid cavities in each airfoil. The fluid (e.g., air) is sufficient in pressure and volume to maintain a minimum fluid flow to each of the interior fluid cavities in the event of a breach due to foreign object damage.

  7. Aerodynamic Response of Turbomachinery Blade Rows to Convecting Density Wakes

    National Research Council Canada - National Science Library

    Tan, Choon

    1999-01-01

    .... In order to characterize the density wake induced force and moment fluctuations a two-dimensional computational study was conducted to simulate the passage of density wakes through a cascade blade row...

  8. A new gaseous detector for tracking: The blade chamber

    International Nuclear Information System (INIS)

    Ambrosi, G.; Battiston, R.; Levi, G.; Barillari, T.; Susinno, G.; Bergsma, F.; Contin, A.; Labbe, J.C.; Laurenti, G.; Mattern, D.; Simonet, G.; Williams, M.C.S.; Zichichi, A.; Boscherini, D.; Bruni, G.; De Pasquale, S.; Giusti, P.; Maccarrone, G.; Nania, R.; O'Shea, V.; Castro, H.; Galvez, J.; Rivera, F.; Schioppa, M.; Sharma, A.

    1990-01-01

    As part of the LAA project at CERN a prototype of a streamer-chamber in which a blade, instead of a wire, is used as the amplification electrode has been built. A big advantage is that the blade can be bent to follow a curve so that a chamber can be built with cells ideally matched to the geometry of the experiment. Moreover, a blade is very rugged, it can withstand severe mechanical shocks and it is also resistant to damage by sparks. The drift time has been measured and a spatial resolution of 250μm has been achieved. Left-right ambiguity can be solved by measuring the charge asymmetry on the walls. The coordinate along the blade is read by external pickup strips. (orig.)

  9. Guidelines to Interpret Results of Mechanical Blade Test

    International Nuclear Information System (INIS)

    Arias Vega, F.; Sanz Martin, J. C.

    1999-01-01

    This report shows the interpretation of full scale rotor blade test results and describes the engineering testing models and coefficients for any feasible rotor blade design, in order to accept and to certify any final manufactured blade as an allowable product, fit for use and working with a completely security during all the wind turbines lifetime. This work was carried out at the Wind Energy Division of the CIEMAT.DER and it is based on the authors technical experience in this field, after many years working on testing blades. Also, this paper contains results of the European wind turbine Standards II relevant to the European Project: JOULE III R.D. where the Wind Energy Division took part as participant too. (Author)

  10. Study of blade clearance effects on centrifugal pumps

    Science.gov (United States)

    Hoshide, R. K.; Nielson, C. E.

    1972-01-01

    A program of analysis, design, fabrication, and testing has been conducted to develop and experimentally verify analytical models to predict the effects of impeller blade clearance on centrifugal pumps. The effect of tip clearance on pump efficiency, and the relationship between the head coefficient and torque loss with tip clearance was established. Analysis were performed to determine the cost variation in design, manufacture, and test that would occur between unshrouded and shrouded impellers. An impeller, representative of typical rocket engine impellers, was modified by removing its front shroud to permit variation of its blade clearances. It was tested in water with special instrumentation to provide measurements of blade surface pressures during operation. Pump performance data were obtained from tests at various impeller tip clearances. Blade pressure data were obtained at the nominal tip clearance. Comparisons of predicted and measured data are given.

  11. Ion beam analysis of gas turbine blades: evaluation of refurbishment ...

    Indian Academy of Sciences (India)

    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.

  12. Turbine blade and non-integral platform with pin attachment

    Science.gov (United States)

    Campbell, Christian X; Eng, Darryl; Marra, John J

    2015-01-27

    Platforms (36, 38) span between turbine blades (23, 24, 25) on a disk (32). Each platform may be individually mounted to the disk by a pin attachment (42). Each platform (36) may have a rotationally rearward edge portion (50) that underlies a forward portion (45) of the adjacent platform (38). This limits centrifugal bending of the rearward portion of the platform, and provides coolant sealing. The rotationally forward edge (44A, 44B) of the platform overlies a seal element (51) on the pressure side (28) of the forwardly adjacent blade, and does not underlie a shelf on that blade. The pin attachment allows radial mounting of each platform onto the disk via tilting (60) of the platform during mounting to provide mounting clearance for the rotationally rearward edge portion (50). This facilitates quick platform replacement without blade removal.

  13. Numerical study of Wavy Blade Section for Wind Turbines

    DEFF Research Database (Denmark)

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

    2016-01-01

    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...... 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....

  14. A Critical Review of Future Materials for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran

    2014-01-01

    focusing several factors like less weight, less price, higher performance, longer life, ease of processing, and capability of recycling. In the present market scenario, wind industry needs to improve their business for onshore and for off-shore applications demonstrating the new blade designs and stating...... 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....

  15. Wind Turbine Blades: An End of Life Perspective

    DEFF Research Database (Denmark)

    Beauson, Justine; Brøndsted, Povl

    2016-01-01

    In 2016, the first offshore windfarm constructed in the world—located in Denmark, near Ravnsborg—is turning 25 years old, and will soon be decommissioned. After decommissioning, most of the material of the turbine can be recycled; only the composite materials found in the blades represent...... a challenge. This part looks at end of life solutions for this material. Wind turbine blade structure and material are described. The ends of life solutions existing and under development are detailed....

  16. Hybrid anisotropic materials for wind power turbine blades

    CERN Document Server

    Golfman, Yosif

    2012-01-01

    Based on rapid technological developments in wind power, governments and energy corporations are aggressively investing in this natural resource. Illustrating some of the crucial new breakthroughs in structural design and application of wind energy generation machinery, Hybrid Anisotropic Materials for Wind Power Turbine Blades explores new automated, repeatable production techniques that expand the use of robotics and process controls. These practices are intended to ensure cheaper fabrication of less-defective anisotropic material composites used to manufacture power turbine blades. This boo

  17. Radial Flow Effects On A Retreating Rotor Blade

    Science.gov (United States)

    2014-05-01

    understood. Experiments were conducted on a rigid two bladed teetering rotor at high advance ratios in a low speed wind tunnel . Particle image...the John Harper low speed wind tunnel described in the previous section with the motor positioned below the rotor . In order to simplify the operations...at 2.5 cm spacing to the suction side of the wing. A 134 (a) Drawing of the wing setup (b) Side view of the rotor blade setup in the wind tunnel

  18. About the problems and perspectives of making precision compressor blades

    Directory of Open Access Journals (Sweden)

    V. E. Galiev

    2014-01-01

    Full Text Available The problems of manufacturing blades with high precision profile geometry are considered in the article. The variant of the technology under development rules out the use of mechanical processing methods for blades airfoil. The article consists of an introduction and six small sections.The introduction sets out the requirements for modern aircraft engines, makes a list of problems arisen in the process of their manufacturing, and marks the relevance of the work.The first section analyzes the existing technology of precision blades. There is an illustration reflecting the stages of the process. Their advantages and disadvantages are marked.The second section provides an illustration, which shows the system-based blades used in the manufacturing process and a model of the work piece using the technology being developed. An analysis of each basing scheme is presented.In the third section we list the existing control methods of geometrical parameters of blades airfoil and present the measurement error data of devices. The special attention is paid to the impossibility to control the accuracy of geometrical parameters of precision blades.The fourth section presents the advantages of the electrochemical machining method with a consistent vibration of tool-electrode and with feeding the pulses of technology current over the traditional method. The article presents data accuracy and surface roughness of the blades airfoil reached owing to precision electrochemical machining. It illustrates machines that implement the given method of processing and components manufactured on them.The fifth section describes the steps of the developed process with justification for the use of the proposed operations.Based on the analysis, the author argues that the application of the proposed process to manufacture the precision compressor blades ensures producing the items that meet the requirements of the drawing.

  19. Hydrodynamics automatic optimization of runner blades for reaction hydraulic turbines

    International Nuclear Information System (INIS)

    Balint, D; Câmpian, V; Nedelcu, D; Megheles, O

    2012-01-01

    The aim of this paper is to optimize the hydrodynamics of the runner blades of hydraulic turbines. The runner presented is an axial Kaplan one, but the methodology is common also to Francis runners. The whole methodology is implemented in the in-house software QTurbo3D. The effect of the runner blades geometry modification upon its hydrodynamics is shown both from energetic and cavitation points of view.

  20. Interaction of Atmospheric Turbulence with Blade Boundary Layer Dynamics on a 5MW Wind Turbine using Blade-Boundary-Layer-Resolved CFD with hybrid URANS-LES.

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, Ganesh [National Renewable Energy Lab. (NREL), Golden, CO (United States); Pennsylvania State Univ., University Park, PA (United States); Brasseur, James [Pennsylvania State Univ., University Park, PA (United States); Univ. of Colorado, Boulder, CO (United States); Lavely, Adam; Jayaraman, Balaji; Craven, Brent

    2016-01-04

    We describe the response of the NREL 5 MW wind turbine blade boundary layer to the passage of atmospheric turbulence using blade-boundary-layer-resolved computational fluid dynamics with hybrid URANS-LES modeling.