WorldWideScience

Sample records for rotor blade structural

  1. Structural characterization of rotor blades through photogrammetry

    Science.gov (United States)

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

    2016-06-01

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

  2. Photogrammetric detection technique for rotor blades structural characterization

    Science.gov (United States)

    Enei, C.; Bernardini, G.; Serafini, J.; Mattioni, L.; Ficuciello, C.; Vezzari, V.

    2015-11-01

    This paper describes an innovative use of photogrammetric detection techniques to experimentally estimate structural/inertial properties of helicopter rotor blades. The identification algorithms for the evaluation of mass and flexural stiffness distributions are an extension of the ones proposed by Larsen, whereas the procedure for torsional properties determination (stiffness and shear center position) is based on the Euler-Prandtl beam theory. These algorithms rely on measurements performed through photogrammetric detection, which requires the collection of digital photos allowing the identification of 3D coordinates of labeled points (markers) on the structure through the correlation of 2D pictures. The displacements are evaluated by comparing the positions of markers in loaded and reference configuration. Being the applied loads known, the structural characteristics can be directly obtained from the measured displacements. The accuracy of the proposed identification algorithms has been firstly verified by comparison with numerical and experimental data, and then applied to the structural characterization of two main rotor blades, designed for ultra-light helicopter applications.

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

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    M. H. Hansen

    2016-11-01

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

  5. Efficient Beam-Type Structural Modeling of Rotor Blades

    DEFF Research Database (Denmark)

    Couturier, Philippe; Krenk, Steen

    2015-01-01

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

  6. Rotor anisotropy as a blade damage indicator for wind turbine structural health monitoring systems

    Science.gov (United States)

    Tcherniak, Dmitri

    2016-06-01

    Structural damage of a rotor blade causes structural anisotropy of the rotor. In rotor dynamic, the anisotropy affects the symmetry of the rotor mode shapes, and the latter can be utilized to detect the blade damage. The mode shape symmetry can be characterized by relative blades' magnitude and phase. The study examines the potential use of these parameters as rotor damage indicators. Firstly the indicators are studied analytically using a simple 6 degrees-of-freedom model of a rotating rotor. Floquet analysis is used due to the time periodic nature of the considered system. Floquet analysis allows one to perform analytical modal decomposition of the system and study the sensitivity of the damage indicators to the amount of damage. Secondly, operational modal analysis (OMA) is involved to extract the same damage indicators from simulated experimental data, which was synthesized via numerical simulations. Finally, the same procedure was applied to operating Vestas V27 wind turbine, first using the simulated experimental data obtained by using aeroelastic simulation code HAWC2 and then using the data acquired during the measurement campaign on a real wind turbine. The study demonstrates that the proposed damage indicators are significantly more sensitive than the commonly used changes in natural frequency, and in contrast to the latter, can also pinpoint the faulty blade. It is also demonstrated that these indicators can be derived from blades vibration data obtained from real life experiment.

  7. Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor Blade Systems

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2004-01-01

    The demands for high efficiency machines initiate a demand for monitoring and active control of vibrations to improve machinery performance and to prolong machinery lifetime. Applying active control to reduce vibrations in flexible bladed rotor-systems imply that several difficulties have...... of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step...... to be overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures...

  8. 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.

  9. Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor-Blade Systems

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2003-01-01

    to be overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures...... of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step...... is reformulated using complex mode theory. Next, a linear constant gain controller for the reformulated system is designed by linear control technique. Finally, this constant gain controller is transformed to a time-periodic form by applying reverse modal transformation. The non-measurable states are estimated...

  10. On the similarity of the Coleman and Lyapunov-Floquet transformations for modal analysis of bladed rotor structures

    DEFF Research Database (Denmark)

    Skjoldan, P.F.; Hansen, Morten Hartvig

    2009-01-01

    Structures with isotropic bladed rotors can be modally analyzed by eigenvalue analysis of time-invariant Coleman transformed equations of motion related to the inertial frame or by Floquet analysis of the periodic equations of motion. The Coleman transformation is here shown to be a special case ...

  11. Development of a model based Structural-Health-Monitoring-Systems for condition monitoring of rotor blades; Entwicklung eines modellgestuetzten Structural-Health-Monitoring-Systems zur Zustandsueberwachung von Rotorblaettern

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, C.; Friedmann, H.; Henkel, F.O. [Woelfel Beratende Ingenieure GmbH und Co.KG, Hoechberg (Germany); Frankenstein, B.; Schubert, L. [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren, Dresden (Germany)

    2010-07-01

    The authors of the contribution under consideration report on a development of a Structural-Health-Monitoring-System which is to supervise the condition of the rotor blades of wind power plants and to detect in time structural changes before total failures. It is based on a combination of measuring techniques from the areas of the led rollers in the ultrasonic range and low-frequency modal analysis. The combination of both techniques was already promisingly used with past investigations of rotor blades. By means of modal analysis, statements to the total behaviour of the structure of rotor blades are possible. Endangered and strongly stressed areas additionally are supervised by led rollers within the ultrasonic range. The authors also report on the conception and execution of a fatigue test at a material rotor blade with a length by 39.1 m.

  12. Integration of dynamic, aerodynamic and structural optimization of helicopter rotor blades

    Science.gov (United States)

    Peters, David A.

    1987-01-01

    The purpose of the research is to study the integration of structural, dynamic, and aerodynamic considerations in the design-optimization process for helicopter rotorblades. This is to be done in three phases. Task 1 is to bring on-line computer codes that could perform the finite-element frequency analyses of rotor blades. The major features of this program are summarized. The second task was to bring on-line an optimization code for the work. Several were tried and it was decided to use CONMIN. Explicit volume constraints on the thicknesses and lumped masses used in the optimization were added. The specific aeroelastic constraint that the center of mass must be forward of the quarter chord in order to prevent flutter was applied. The bending-torsion coupling due to cg-ea offset within the blade cross section was included. Also included were some very simple stress constraints. The first three constraints are completed, and the fourth constraint is being completed.

  13. 14 CFR 27.661 - Rotor blade clearance.

    Science.gov (United States)

    2010-01-01

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

  14. 14 CFR 29.661 - Rotor blade clearance.

    Science.gov (United States)

    2010-01-01

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

  15. Stainless-Steel-Foam Structures Evaluated for Fan and Rotor Blades

    Science.gov (United States)

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

    2005-01-01

    The goal of this project is to use a sandwich structure design, consisting of two stainlesssteel face sheets and a stainless-steel-foam core, to fabricate engine fan and propeller blades. Current fan blades are constructed either of polymer matrix composites (PMCs) or hollow titanium alloys. The PMC blades are expensive and have poor impact resistance on their leading edges, thereby requiring a metallic leading edge to satisfy the Federal Aviation Administration s impact requirements relating to bird strikes. Hollow titanium blades cost more to fabricate because of the intrinsically difficult fabrication issues associated with titanium alloys. However, both these current concepts produce acceptable lightweight fan blades.

  16. Multiple piece turbine rotor blade

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Keith D.; Plank, William L.

    2016-07-19

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

  17. Design modification in rotor blade of turbo molecular pump

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Munawar, E-mail: muniqbal@yahoo.com [Centre for High Energy Physics, University of the Punjab, Quaid-e-Azam, Campus, Lahore 54590 (Pakistan); Wasy, Abdul [Department of Mechanical Engineering, University of Engineering and Technology, Taxila 47050 (Pakistan); Batani, Dimitri [Centre Lasers Intenses et Applications, Universite Bordeaux 1, Liberation, 33405 Talence cedex (France); Rashid, Haris [Centre for High Energy Physics, University of the Punjab, Quaid-e-Azam, Campus, Lahore 54590 (Pakistan); Lodhi, M.A.K. [Department of Physics, Texas Tech University, Lubbock Texas, 79409 (United States)

    2012-06-21

    Performance of a Turbo Molecular Pump (TMP) is strongly related to the frequency of the rotor. As rpm increases deflection in the rotor blades starts to occur. Therefore, quality of material and blade design has been modified in order to obtain stable performance at higher speed. To reduce the deformation, stiffer material and change in blade design have been calculated. Significant improvement has been achieved in modeling the blade design using CATIA software. The analysis has been performed by ANSYS workbench. It is shown that the modification in the blade design of TMP rotor has reduced the structural deformation up to 66 percent of the deformation produced in the original blade design under the same conditions. Modified design achieved additional 23 percent rpm which increased TMP's efficiency.

  18. Design modification in rotor blade of turbo molecular pump

    Science.gov (United States)

    Iqbal, Munawar; Wasy, Abdul; Batani, Dimitri; Rashid, Haris; Lodhi, M. A. K.

    2012-06-01

    Performance of a Turbo Molecular Pump (TMP) is strongly related to the frequency of the rotor. As rpm increases deflection in the rotor blades starts to occur. Therefore, quality of material and blade design has been modified in order to obtain stable performance at higher speed. To reduce the deformation, stiffer material and change in blade design have been calculated. Significant improvement has been achieved in modeling the blade design using CATIA software. The analysis has been performed by ANSYS workbench. It is shown that the modification in the blade design of TMP rotor has reduced the structural deformation up to 66 percent of the deformation produced in the original blade design under the same conditions. Modified design achieved additional 23 percent rpm which increased TMP's efficiency.

  19. Advanced topics on rotor blade full-scale structural fatigue testing and requirements

    DEFF Research Database (Denmark)

    Berring, Peter; Fedorov, Vladimir; Belloni, Federico

    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]. This report deals with more advanced topics...... for fatigue testing of wind turbine blades. One challenge is how to fatigue test blades under realistic conditions. In order to study this topic a finite element based multibody formulation using the floating frame of reference approach is used to study fatigue loading under different external conditions...

  20. Extension-twist coupling optimization in composite rotor blades

    Science.gov (United States)

    Ozbay, Serkan

    2005-07-01

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

  1. Aeroelastic analysis for helicopter rotor blades with time-variable, non-linear structural twist and multiple structural redundancy: Mathematical derivation and program user's manual

    Science.gov (United States)

    Bielawa, R. L.

    1976-01-01

    The differential equations of motion for the lateral and torsional deformations of a nonlinearly twisted rotor blade in steady flight conditions together with those additional aeroelastic features germane to composite bearingless rotors are derived. The differential equations are formulated in terms of uncoupled (zero pitch and twist) vibratory modes with exact coupling effects due to finite, time variable blade pitch and, to second order, twist. Also presented are derivations of the fully coupled inertia and aerodynamic load distributions, automatic pitch change coupling effects, structural redundancy characteristics of the composite bearingless rotor flexbeam - torque tube system in bending and torsion, and a description of the linearized equations appropriate for eigensolution analyses. Three appendixes are included presenting material appropriate to the digital computer program implementation of the analysis, program G400.

  2. Aerodynamics of Rotor Blades for Quadrotors

    CERN Document Server

    Bangura, Moses; Naldi, Roberto; Mahony, Robert

    2016-01-01

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

  3. Blade tip vortex measurements on actively twisted rotor blades

    Science.gov (United States)

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

    2017-05-01

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

  4. Design optimization for active twist rotor blades

    Science.gov (United States)

    Mok, Ji Won

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

  5. Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.

    2013-01-01

    The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for

  6. Rotor blade online monitoring and fault diagnosis technology research

    DEFF Research Database (Denmark)

    Tesauro, Angelo; Pavese, Christian; Branner, Kim

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

  7. Further development of the swinging-blade Savonius rotor

    Science.gov (United States)

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

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

  8. Evaluation of Rotor Structural and Aerodynamic Loads Using Measured Blade Properties

    Science.gov (United States)

    2012-09-01

    German-Dutch wind tunnel (DNW) by a joint research team from the German DLR, the French ONERA , NASA Langley, DNW, and the U.S. Army [1]. The main...is based on the ONERA -EDLIN unsteady airfoil theory combined with C81 airfoil table look-up. For the vortex wake representation, the free wake...acknowledge the support of HART I partners – DLR, DNW, NASA, ONERA , and AFDD. The authors acknowledge Benton Lau who began the blade property measurement but

  9. Shape Optimization of Rotor Blade for Pulp Pressure Screen Based on FLUENT

    Directory of Open Access Journals (Sweden)

    Qu Qingwen

    2013-10-01

    Full Text Available The study got two modified blades by changing the structure and shape of the rotor blade of the pressure screen. Pulp flow field in the same condition is numerically simulated by the fluid dynamics software FLUENT. The pressure distribution is showed especially in the location of the sieve drum circle. The ideal blade structure is obtained by the pressure field compared with conventional blades. It has strong cleaning ability and not easy to blockage sieve drum. The shape of the rotor blade is optimized. The blade shape is analyzed to the influence law of energy consumption. It is proved that the new rotor has energy-saving advantages. It is significant to improve the performance of pulp screening equipment. The theoretical support for select of blade shape of bars is provided by analysis of flow field.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  11. Rotor blade monitoring of wind turbines; Ueberwachung von Rotorblaettern von Windkraftanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Frankenstein, Bernd; Schubert, Lars; Klesse, Thomas; Schulze, Eberhard [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren (IZFP), Dresden (Germany); Friedmann, Herbert; Ebert, Carsten [Woelfel Beratende Ingenieure GmbH und Co. KG, Hoechberg (Germany)

    2009-07-01

    This work describes the development of a structural health monitoring system (SHM) which monitors the condition of rotor blades of wind turbines, and detects and locates structural changes before final failure. It is based on a combination of measuring techniques with guided waves in the ultrasound range and low frequency modal analysis. The combination of both techniques has been applied promisingly in rotor blade investigations so far. Modal analysis allows for statements regarding the structural behaviour of the rotor blade structure. Areas of higher risk and stress are additionally monitored by guided waves in the ultrasound range. (orig.)

  12. Tower and rotor blade vibration test results for a 100-kilowatt wind turbine

    Science.gov (United States)

    Linscott, B. S.; Shapton, W. R.; Brown, D.

    1976-01-01

    The predominant natural frequencies and mode shapes for the tower and the rotor blades of the ERDA-NASA 100-kW wind turbine were determined. The tests on the tower and the blades were conducted both before and after the rotor blades and the rotating machinery were installed on top of the tower. The tower and each blade were instrumented with an accelerometer and impacted by an instrumented mass. The tower and blade structure was analyzed by means of NASTRAN, and computed values agree with the test data.

  13. Tip cap for a turbine rotor blade

    Science.gov (United States)

    Kimmel, Keith D

    2014-03-25

    A turbine rotor blade with a spar and shell construction, and a tip cap that includes a row of lugs extending from a bottom side that form dovetail grooves that engage with similar shaped lugs and grooves on a tip end of the spar to secure the tip cap to the spar against radial displacement. The lug on the trailing edge end of the tip cap is aligned perpendicular to a chordwise line of the blade in the trailing edge region in order to minimize stress due to the lugs wanting to bend under high centrifugal loads. A two piece tip cap with lugs at different angles will reduce the bending stress even more.

  14. Composite rotor blades for large wind energy installations

    Science.gov (United States)

    Kussmann, A.; Molly, J.; Muser, D.

    1980-01-01

    The design of large wind power systems in Germany is reviewed with attention given to elaboration of the total wind energy system, aerodynamic design of the rotor blade, and wind loading effects. Particular consideration is given to the development of composite glass fiber/plastic or carbon fiber/plastic rotor blades for such installations.

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

    Science.gov (United States)

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

    1983-01-01

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

  16. On the performance analysis of Savonius rotor with twisted blades

    Energy Technology Data Exchange (ETDEWEB)

    Saha, U.K.; Rajkumar, M. Jaya [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati-781 039 (India)

    2006-09-15

    The present investigation is aimed at exploring the feasibility of twisted bladed Savonius rotor for power generation. The twisted blade in a three-bladed rotor system has been tested in a low speed wind tunnel, and its performance has been compared with conventional semicircular blades (with twist angle of 0{sup o}). Performance analysis has been made on the basis of starting characteristics, static torque and rotational speed. Experimental evidence shows the potential of the twisted bladed rotor in terms of smooth running, higher efficiency and self-starting capability as compared to that of the conventional bladed rotor. Further experiments have been conducted in the same setup to optimize the twist angle. (author)

  17. Helicopter Rotor Blade Monitoring using Autonomous Wireless Sensor Network

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Tinga, Tiedo; Basu, B.

    2013-01-01

    The advancement on Wireless Sensor Networks for vibration monitoring presents important possibilities for helicopter rotor health and usage monitoring. While main rotor blades account for the main source of lift for helicopters, rotor induced vibration establishes an important source for understandi

  18. Integral Twist Actuation of Helicopter Rotor Blades for Vibration Reduction

    Science.gov (United States)

    Shin, SangJoon; Cesnik, Carlos E. S.

    2001-01-01

    Active integral twist control for vibration reduction of helicopter rotors during forward flight is investigated. The twist deformation is obtained using embedded anisotropic piezocomposite actuators. An analytical framework is developed to examine integrally-twisted blades and their aeroelastic response during different flight conditions: frequency domain analysis for hover, and time domain analysis for forward flight. Both stem from the same three-dimensional electroelastic beam formulation with geometrical-exactness, and axe coupled with a finite-state dynamic inflow aerodynamics model. A prototype Active Twist Rotor blade was designed with this framework using Active Fiber Composites as the actuator. The ATR prototype blade was successfully tested under non-rotating conditions. Hover testing was conducted to evaluate structural integrity and dynamic response. In both conditions, a very good correlation was obtained against the analysis. Finally, a four-bladed ATR system is built and tested to demonstrate its concept in forward flight. This experiment was conducted at NASA Langley Tansonic Dynamics Tunnel and represents the first-of-a-kind Mach-scaled fully-active-twist rotor system to undergo forward flight test. In parallel, the impact upon the fixed- and rotating-system loads is estimated by the analysis. While discrepancies are found in the amplitude of the loads under actuation, the predicted trend of load variation with respect to its control phase correlates well. It was also shown, both experimentally and numerically, that the ATR blade design has the potential for hub vibratory load reduction of up to 90% using individual blade control actuation. Using the numerical framework, system identification is performed to estimate the harmonic transfer functions. The linear time-periodic system can be represented by a linear time-invariant system under the three modes of blade actuation: collective, longitudinal cyclic, and lateral cyclic. A vibration

  19. Investigation of Maximum Blade Loading Capability of Lift-Offset Rotors

    Science.gov (United States)

    Yeo, Hyeonsoo; Johnson, Wayne

    2013-01-01

    Maximum blade loading capability of a coaxial, lift-offset rotor is investigated using a rotorcraft configuration designed in the context of short-haul, medium-size civil and military missions. The aircraft was sized for a 6600-lb payload and a range of 300 nm. The rotor planform and twist were optimized for hover and cruise performance. For the present rotor performance calculations, the collective pitch angle is progressively increased up to and through stall with the shaft angle set to zero. The effects of lift offset on rotor lift, power, controls, and blade airloads and structural loads are examined. The maximum lift capability of the coaxial rotor increases as lift offset increases and extends well beyond the McHugh lift boundary as the lift potential of the advancing blades are fully realized. A parametric study is conducted to examine the differences between the present coaxial rotor and the McHugh rotor in terms of maximum lift capabilities and to identify important design parameters that define the maximum lift capability of the rotor. The effects of lift offset on rotor blade airloads and structural loads are also investigated. Flap bending moment increases substantially as lift offset increases to carry the hub roll moment even at low collective values. The magnitude of flap bending moment is dictated by the lift-offset value (hub roll moment) but is less sensitive to collective and speed.

  20. CFD analysis of rotating two-bladed flatback wind turbine rotor.

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, C.P. (University of California, David, CA); Chao, David D.; Berg, Dale E. (University of California, David, CA)

    2008-04-01

    The effects of modifying the inboard portion of the NREL Phase VI rotor using a thickened, flatback version of the S809 design airfoil are studied using a three-dimensional Reynolds-averaged Navier-Stokes method. A motivation for using such a thicker airfoil design coupled with a blunt trailing edge is to alleviate structural constraints while reducing blade weight and maintaining the power performance of the rotor. The calculated results for the baseline Phase VI rotor are benchmarked against wind tunnel results obtained at 10, 7, and 5 meters per second. The calculated results for the modified rotor are compared against those of the baseline rotor. The results of this study demonstrate that a thick, flatback blade profile is viable as a bridge to connect structural requirements with aerodynamic performance in designing future wind turbine rotors.

  1. Experimental study of complex flow and turbulence structure around a turbomachine rotor blade operating behind a row of Inlet Guide Vanes (IGVS)

    Science.gov (United States)

    Soranna, Francesco

    The flow and turbulence around a rotor blade operating downstream of a row of Inlet Guide Vanes (IGV) are investigated experimentally in a refractive index matched turbomachinery facility that provides unobstructed view of the entire flow field. High resolution 2D and Stereoscopic PIV measurements are performed both at midspan and in the tip region of the rotor blade, focusing on effects of wake-blade, wake-boundary-layer and wake-wake interactions. We first examine the modification to the shape of an IGV-wake as well as to the spatial distribution of turbulence within it as the wake propagates along the rotor blade. Due to the spatially non-uniform velocity distribution, the IGV wake deforms through the rotor passage, expanding near the leading edge and shrinking near the trailing edge. The turbulence within this wake becomes spatially non-uniform and highly anisotropic as a result of interaction with the non-uniform strain rate field within the rotor passage. Several mechanisms, which are associated with rapid straining and highly non-uniform production rate (P), including negative production on the suction side of the blade, contribute to the observed trends. During IGV-wake impingement, the suction side boundary layer near the trailing edge becomes significantly thinner, with lower momentum thickness and more stable profile compared to other phases at the same location. Analysis of available terms in the integral momentum equation indicates that the phase-averaged unsteady term is the main contributor to the decrease in momentum thickness within the impinging wake. Thinning of the boundary/shear layer extends into the rotor near wake, making it narrower and increasing the phase averaged shear velocity gradients and associated production term just downstream of the trailing edge. Consequently, the turbulent kinetic energy (TKE) increases causing as much as 75% phase-dependent variations in peak TKE magnitude. Further away from the blade, the rotor wake is bent

  2. Response studies of rotors and rotor blades with application to aeroelastic tailoring

    Science.gov (United States)

    Friedmann, P. P.

    1982-01-01

    Various tools for the aeroelastic stability and response analysis of rotor blades in hover and forward flight were developed and incorporated in a comprehensive package capable of performing aeroelastic tailoring of rotor blades in forward flight. The results indicate that substantial vibration reductions, of order 15-40%, in the vibratory hub shears can be achieved by relatively small modifications of the initial design. Furthermore the optimized blade can be up to 20% lighter than the original design. Accomplishments are reported for the following tasks: (1) finite element modeling of rotary-wing aeroelastic problems in hover and forward flight; (2) development of numerical methods for calculating the aeroelastic response and stability of rotor blades in forward fight; (3) formulation of the helicopter air resonance problem in hover with active controls; and (4) optimum design of rotor blades for vibration reduction in forward flight.

  3. 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.

  4. Thermographic inspection of a wind turbine rotor blade segment utilizing natural conditions as excitation source, Part I: Solar excitation for detecting deep structures in GFRP

    Science.gov (United States)

    Worzewski, Tamara; Krankenhagen, Rainer; Doroshtnasir, Manoucher; Röllig, Mathias; Maierhofer, Christiane; Steinfurth, Henrik

    2016-05-01

    This study evaluates whether subsurface features in rotor blades, mainly made of Glass Fibre Reinforced Plastics (GFRP), can generally be detected with "solar thermography". First, the suitability of the sun is tested for acting as a heat source for applying active thermography on a 30 mm thick GFRP test specimen. Second, a defective rotor blade segment is inspected outdoors under ideal natural conditions using the sun as excitation source. Additionally, numerical FEM-simulations are performed and the comparability between experiment and simulation is evaluated for outdoor measurements.

  5. 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).

  6. Predesign study for a modern 4-bladed rotor for the NASA rotor systems research aircraft

    Science.gov (United States)

    Bishop, H. E.; Burkam, J. E.; Heminway, R. C.; Keys, C. N.; Smith, K. E.; Smith, J. H.; Staley, J. A.

    1981-01-01

    Trade-off study results and the rationale for the final selection of an existing modern four-bladed rotor system that can be adapted for installation on the Rotor Systems Research Aircraft (RSRA) are reported. The results of the detailed integration studies, parameter change studies, and instrumentation studies and the recommended plan for development and qualification of the rotor system is also given. Its parameter variants, integration on the RSRA, and support of ground and flight test programs are also discussed.

  7. Lift capability prediction for helicopter rotor blade-numerical evaluation

    Science.gov (United States)

    Rotaru, Constantin; Cîrciu, Ionicǎ; Luculescu, Doru

    2016-06-01

    The main objective of this paper is to describe the key physical features for modelling the unsteady aerodynamic effects found on helicopter rotor blade operating under nominally attached flow conditions away from stall. The unsteady effects were considered as phase differences between the forcing function and the aerodynamic response, being functions of the reduced frequency, the Mach number and the mode forcing. For a helicopter rotor, the reduced frequency at any blade element can't be exactly calculated but a first order approximation for the reduced frequency gives useful information about the degree of unsteadiness. The sources of unsteady effects were decomposed into perturbations to the local angle of attack and velocity field. The numerical calculus and graphics were made in FLUENT and MAPLE soft environments. This mathematical model is applicable for aerodynamic design of wind turbine rotor blades, hybrid energy systems optimization and aeroelastic analysis.

  8. 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.

  9. Equations of motion for a rotor blade, including gravity, pitch action and rotor speed variations

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    2007-01-01

    This paper extends Hodges-Dowell's partial differential equations of blade motion, by including the effects from gravity, pitch action and varying rotor speed. New equations describing the pitch action and rotor speeds are also derived. The physical interpretation of the individual terms...... in the equations is discussed. The partial differential equations of motion are approximated by ordinary differential equations of motion using an assumed mode method. The ordinary differential equations are used to simulate a sudden pitch change of a rotating blade. This work is a part of a project on pitch blade...

  10. Recycling of used rotor blades; Der Kreislauf schliesst sich

    Energy Technology Data Exchange (ETDEWEB)

    Schmidl, Erwin; Hinrichs, Stephan [Holcim Deutschlands AG, Hamburg (Germany)

    2010-06-15

    Until recently, used wind rotor blades were shreddered and combusted in waste incinerators. This is problematic because of high fine dust emissions and of sharp-edged fibre composite residues escaping into the environment. It was also a costly and time-consuming procedure. Recycling into other products is impracticable because there are more than enough low-grade recycled plastic materials available. The Holcim AG of the German state of Schleswig-Holstein filed a patent application for a new process in which the rotor blades will be used up completely, without residues, in a cement clinker plant. (orig.)

  11. Savonius rotor using swinging blades as an augmentation system

    Science.gov (United States)

    Aldos, T. K.

    The power output from a Savonius rotor can be improved by reducing the drag force on the up-wind blades. A new method of doing this is experimentally investigated in the present work. The method depends on allowing the rotor blades to swing back when they are on the upwind stroke. A high and real power augmentation may be achieved by the new system at an optimum angle of swing. The system is independent of wind direction, is simple to construct, and requires no additional accessories.

  12. Crack Propagation in Compressor Rotor Blade

    Science.gov (United States)

    2012-08-01

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

  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. Model and Stability Analysis of a Flexible Bladed Rotor

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available This paper presents a fully bladed flexible rotor and outlines the associated stability analysis. From an energetic approach based on the complete energies and potentials for Euler-Bernoulli beams, a system of equations is derived, in the rotational frame, for the rotor. This later one is made of a hollow shaft modelled by an Euler-Bernoulli beam supported by a set of bearings. It is connected to a rigid disk having a rotational inertia. A full set of flexible blades is also modelled by Euler-Bernoulli beams clamped in the disk. The flexural vibrations of the blades as well as those of the shaft are considered. The evolution of the eigenvalues of this rotor, in the corotational frame, is studied. A stability detection method, bringing coalescence and loci separation phenomena to the fore, in case of an asymmetric rotor, is undertaken in order to determine a parametric domain where turbomachinery cannot encounter damage. Finally, extensive parametric studies including the length and the stagger angle of the blades as well as their flexibility are presented in order to obtain robust criteria for stable and unstable areas prediction.

  15. CFD simulation and analysis for Savonius rotors with different blade configuration

    Science.gov (United States)

    Lin, Ching-Huei; Klimina, Liubov A.

    2014-12-01

    Savonius rotor is seldom applied in wind power generation system due to its lower aerodynamic efficiency. But studies about Savonius rotor still continued since the rotor structure is simpler and the manufacturing cost is lower. Computational fluid dynamics simulations are adopted to compare the output power, torque and power coefficient (Cp) for the conventional two-blade Savonius rotors with three different aspect ratios but the same swept area under the same wind condition to investigate the optimum blade configuration. The rotor with tall and thin configuration is found to have the maximum output power and Cp. The rotor with short and wide configuration has the maximum torque but the minimum Cp. The current result suggests the optimum aspect ratio is 4/1. The influence related to the circular cover plates at two ends of rotor was studied also. It reveals that both the torque and power coefficient for Savonius rotor with end-plates are larger than that without end-plates.

  16. A new approach to helicopter rotor blade research instrumentation

    Science.gov (United States)

    Knight, V. H., Jr.

    1978-01-01

    A rotor-blade-mounted telemetry instrumentation system developed and used in flight tests by the NASA/Langley Research Center is described. The system uses high-speed digital techniques to acquire research data from miniature pressure transducers on advanced rotor airfoils which are flight tested using an AH-1G helicopter. The system employs microelectronic PCM multiplexer-digitizer stations located remotely on the blade and in a hub-mounted metal canister. The electronics contained in the canister digitizes up to 16 sensors, formats this data with serial PCM data from the remote stations, and transmits the data from the canister which is above the plane of the rotor. Data is transmitted over an RF link to the ground for real-time monitoring and to the helicopter fuselage for tape recording.

  17. 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.

  18. Neutron radiography and other NDE tests of main rotor helicopter blades

    CSIR Research Space (South Africa)

    De Beer, FC

    2004-10-01

    Full Text Available leading to aircraft structural failures, are addressed by various NDE techniques. In a combined investigation by means of visual inspection, X-ray radiography and shearography on helicopter main rotor blades, neutron radiography (NRad) at SAFARI-1 research...

  19. Effect of blade tip winglet on the performance of a highly loaded transonic compressor rotor

    Institute of Scientific and Technical Information of China (English)

    Han Shaobing; Zhong Jingjun

    2016-01-01

    The tip leakage flow has an important influence on the performance of transonic com-pressor. Blade tip winglet has been proved to be an effective method to control the tip leakage flow in compressor, while the physical mechanisms of blade tip winglet have been poorly understood. A numerical study for a highly loaded transonic compressor rotor has been conducted to understand the effect of varying the location of blade tip winglet on the performance of the rotor. Two kinds of tip winglet were designed and investigated. The effects of blade tip winglet on the compressor over-all performance, stability and tip flow structure were presented and discussed. It is found that the interaction of the tip winglet with the flow in the tip region is different when the winglet is located at suction-side or pressure-side of the blade tip. Results indicate that the suction-side winglet (SW) is ineffective to improve the performance of compressor rotor. In addition, a significant stall range extension equivalent to 33.74% with a very small penalty in efficiency can be obtained by the pressure-side winglet (PW). An attempt has been made to explain the fundamental mechanisms of blade tip winglet in detail.

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

    Science.gov (United States)

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

    1997-01-01

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

  1. Optimization model for rotor blades of horizontal axis wind turbines

    Institute of Scientific and Technical Information of China (English)

    LIU Xiong; CHEN Yan; YE Zhiquan

    2007-01-01

    This paper presents an optimization model for rotor blades of horizontal axis wind turbines. The model refers to the wind speed distribution function on the specific wind site, with an objective to satisfy the maximum annual energy output. To speed up the search process and guarantee a global optimal result, the extended compact genetic algorithm (ECGA) is used to carry out the search process.Compared with the simple genetic algorithm, ECGA runs much faster and can get more accurate results with a much smaller population size and fewer function evaluations. Using the developed optimization program, blades of a 1.3 MW stall-regulated wind turbine are designed. Compared with the existing blades, the designed blades have obviously better aerodynamic performance.

  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. Pressure coefficient evolutions on the blades of a Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Chauvin, A.; Guignard, S. [UMRR 7343, Marseilles (France). Lab. IUSTI; Kamoun, B. [Faculte des Sciences de Sfax (Tunisia). Lab. de Physique

    2012-07-01

    Measurements of the pressure field distribution on the blades of a vertical axis Savonius wind machine are presented. The rotor used in the wind tunnel is a two blades cylindrical shape with a central gap. Pressure gauges are placed on each side of a blade, so the pressure jumps between intrados and extrados of a blade during a whole rotation are drawn. In the static configuration, the machine is disposed at various incidences. The determination of pressure jumps allows to calculate the static torque of the machine versus the incidence angle. In the dynamic situation the machine is rotating at various frequencies and gauges signals are varying dynamically of course with the incidence. The dynamic torque coefficient is calculated. Evolutions of the starting torque and starting conditions are then described and dynamic effects on torque evolution are presented. (orig.)

  4. 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...

  5. 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.

  6. Control of Rotor-Blade Coupled Vibrations Using Shaft-Based Actuation

    DEFF Research Database (Denmark)

    Christensen, Rene H.; Santos, Ilmar

    2006-01-01

    When implementing active control into bladed rotating machines aiming at reducing blade vibrations, it can be shown that blade as well as rotor vibrations can in fact be controlled by the use of only shaft-based actuation. Thus the blades have to be deliberately mistuned. This paper investigates...... of modal controllability and observability converge toward steady levels as the degree of mistuning is increased. Finally, experimental control results are presented to prove the theoretical conclusions and to show the feasibility of controlling rotor and blade vibrations by means of shaft-based actuation...... the dynamical characteristics of a mistuned bladed rotor and shows how, why and when a bladed rotor becomes controllable and observable if properly mistuned. As part of such investigation modal controllability and observability of a tuned as well as a mistuned coupled rotor-blade system are analysed...

  7. Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅰ: Experimental Study of Bird Impact

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The conditions of experiment for bird impact to blades have been improved. The experiment of bird impact to the fan rotor blades of an aeroengine is carried out. Through analyzing the transient state response of blades impacted by bird and the change of blade profile before and after the impact, the anti-bird impact performance of blades in the first fan rotor is verified. The basis of anti-foreign object damage design for the fan rotor blades of an aeroengine is provided.

  8. Preform spar cap for a wind turbine rotor blade

    Science.gov (United States)

    Livingston, Jamie T [Simpsonville, SC; Driver, Howard D [Greer, SC; van Breugel, Sjef [Enschede, NL; Jenkins, Thomas B [Cantonment, FL; Bakhuis, Jan Willem [Nijverdal, NL; Billen, Andrew J [Daarlerveen, NL; Riahi, Amir [Pensacola, FL

    2011-07-12

    A spar cap for a wind turbine rotor blade. The spar cap may include multiple preform components. The multiple preform components may be planar sheets having a swept shape with a first end and a second end. The multiple preform components may be joined by mating the first end of a first preform component to the second end of a next preform component, forming the spar cap.

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

    DEFF Research Database (Denmark)

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

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

  10. Performance of twist-coupled blades on variable speed rotors

    Energy Technology Data Exchange (ETDEWEB)

    Lobitz, D.W.; Veers, P.S.; Laino, D.J.

    1999-12-07

    The load mitigation and energy capture characteristics of twist-coupled HAWT blades that are mounted on a variable speed rotor are investigated in this paper. These blades are designed to twist toward feather as they bend with pretwist set to achieve a desirable twist distribution at rated power. For this investigation, the ADAMS-WT software has been modified to include blade models with bending-twist coupling. Using twist-coupled and uncoupled models, the ADAMS software is exercised for steady wind environments to generate C{sub p} curves at a number of operating speeds to compare the efficiencies of the two models. The ADAMS software is also used to generate the response of a twist-coupled variable speed rotor to a spectrum of stochastic wind time series. This spectrum contains time series with two mean wind speeds at two turbulence levels. Power control is achieved by imposing a reactive torque on the low speed shaft proportional to the RPM squared with the coefficient specified so that the rotor operates at peak efficiency in the linear aerodynamic range, and by limiting the maximum RPM to take advantage of the stall controlled nature of the rotor. Fatigue calculations are done for the generated load histories using a range of material exponents that represent materials from welded steel to aluminum to composites, and results are compared with the damage computed for the rotor without twist-coupling. Results indicate that significant reductions in damage are achieved across the spectrum of applied wind loading without any degradation in power production.

  11. Tip gap height effects on flow structure and heat/mass transfer over plane tip of a high-turning turbine rotor blade

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Woo [School of Mechanical Engineering, Kumoh National Institute of Technology, 1 Yangho-dong, Gumi, Gyeongbuk 730-701 (Korea, Republic of)], E-mail: swlee@kumoh.ac.kr; Moon, Hyun Suk; Lee, Seong Eun [School of Mechanical Engineering, Kumoh National Institute of Technology, 1 Yangho-dong, Gumi, Gyeongbuk 730-701 (Korea, Republic of)

    2009-04-15

    The effects of tip gap height-to-chord ratio, h/c, on the flow structure and heat/mass transfer over the plane tip surface of a large-scale high-turning turbine rotor blade have been investigated for h/c = 1.0%, 2.0%, 3.0% and 4.0%. For near-wall tip gap flow visualizations, a high-resolution oil film method is employed, and the naphthalene sublimation technique is used for local heat/mass transfer rate measurements. From the tip surface visualizations, a pair of vortices named 'tip gap vortices' is identified in the leading edge region within the tip gap. The overall tip gap flow is characterized not only by the tip gap vortices but also by the flow separation/re-attachment process along the pressure-side tip edge. Within the separation bubble, there exist complicated near-wall flows moving toward a mid-chord flow converging area. With increasing h/c, the tip gap vortices, the flow separation/re-attachment, and the converging flows within the separation bubble tend to be intensified. In general, higher thermal load is found along the loci of the tip gap vortices and along the re-attachment line, while lower thermal load is observed behind the tip gap vortex system and near the mid-chord flow converging area. Heat/mass transfer characteristics with the variation of h/c are discussed in detail in conjunction with the tip gap flow features. Based on the flow visualizations and heat/mass transfer data, new realistic tip gap flow models have been proposed for h/c = 1.0 and 4.0%.

  12. Measurement and Modelling of Multicopter UAS Rotor Blades in Hover

    Science.gov (United States)

    Nowicki, Nathalie

    2016-01-01

    Multicopters are becoming one of the more common and popular type of unmanned aircraft systems (UAS) which have both civilian and military applications. One example being the concept of drone deliveries proposed by the distribution company Amazon [1]. The electrical propulsion is considered to have both faster and easier deliveries and also environmental benefits compared to other vehicles that still use fossil fuel. Other examples include surveillance and just simple entertainment. The reason behind their success is often said to be due to their small size, relatively low cost, simple structure and finally simple usage. With an increase in the UAS market comes challenges in terms of security, as both people and other aircrafts could be harmed if not used correctly. Therefore further studies and regulations are needed to ensure that future use of drones, especially in the civilian and public sectors, are safe and efficient. Thorough research has been done on full scale, man or cargo transporting, helicopters so that most parts of flight and performance are fairly well understood. Yet not much of it have been verified for small multicopters. Until today many studies and research projects have been done on the control systems, navigation and aerodynamics of multicopters. Many of the methods used today for building multicopters involve a process of trial an error of what will work well together, and once that is accomplished some structural analysis of the multicopter bodies might be done to verify that the product will be strong enough and have a decent aerodynamic performance. However, not much has been done on the research of the rotor blades, especially in terms of structural stress analyses and ways to ensure that the commonly used parts are indeed safe and follow safety measures. Some producers claim that their propellers indeed have been tested, but again that usually tends towards simple fluid dynamic analyses and even simpler stress analyses. There is no real

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-10

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

  14. Active damping of flexible rotor blade dynamics using electrorheological-fluid-based actuators

    Science.gov (United States)

    Wereley, Norman M.

    1994-05-01

    Advanced rotor systems including hingeless and bearingless rotors have air and ground resonance instabilities due to coalescence of low-frequency rotor modes with landing gear and fuselage modes, respectively. This coalescence is of difficulty due to the direct connection of the rotor blade in these advanced rotor systems to the rotor hub using a flexure or flexbeam. We are currently exploring the mitigation of this modal coalescence through the use of active damping techniques and electro-rheological fluid technology.

  15. Boundary Layer Transition Detection on a Rotor Blade Using Rotating Mirror Thermography

    Science.gov (United States)

    Heineck, James T.; Schuelein, Erich; Raffel, Markus

    2014-01-01

    Laminar-to-turbulent transition on a rotor blade in hover has been imaged using an area-scan infrared camera. A new method for tracking a blade using a rotating mirror was employed. The mirror axis of rotation roughly corresponded to the rotor axis of rotation and the mirror rotational frequency is 1/2 that of the rotor. This permitted the use of cameras whose integration time was too long to prevent image blur due to the motion of the blade. This article will show the use of this method for a rotor blade at different collective pitch angles.

  16. Control of LP Turbine Rotor Blade Underloading Using Stator Blade Compound Lean at Root

    Institute of Scientific and Technical Information of China (English)

    PiotrLampart

    2000-01-01

    Due to a large gradient of reaction,LP rotor blades remain underloaded at the root over some range of volumetric flow rates.An interesting design to control the flow through the root passage of the overloaded stator and underloaded moving blade row is compound lean at the root of stator blades.The paper describes results of numerical investigations from a 3D NS solver FlowER conducted for several configurations of stator blade compund lean.The computations are carried out for a wide range of volumetric flow rates.accounting for the nominal operating regime as well as low and high load.It is found that compund lean induces additional blade force.streamwise curature and redistribution of flow parameters in the stage,including pressure and mass flow rate spanwise that can improve the flow conditions in both the stator and the rotor.The obtained efficiency improvements depend greatly on the flow regime,with the highest gains in the region of low load.

  17. Structural analysis of wind turbine rotors for NSF-NASA Mod-0 wind power system

    Science.gov (United States)

    Spera, D. A.

    1976-01-01

    Preliminary estimates are presented of vibratory loads and stresses in hingeless and teetering rotors for the proposed NSF-NASA Mod-0 wind power system. Preliminary blade design utilizes a tapered tubular aluminum spar which supports nonstructural aluminum ribs and skin and is joined to the rotor hub by a steel shank tube. Stresses in the shank of the blade are calculated for static, rated, and overload operating conditions. Blade vibrations were limited to the fundamental flapping modes, which were elastic cantilever bending for hingeless rotor blades and rigid-body rotation for teetering rotor blades. The MOSTAB-C computer code was used to calculate aerodynamic and mechanical loads. The teetering rotor has substantial advantages over the hingeless rotor with respect to shank stresses, fatigue life, and tower loading. The hingeless rotor analyzed does not appear to be structurally stable during overloads.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-11-15

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

  19. Experimental and Numerical Study of Rotor Dynamics of a Two- and Three-Bladed Wind Turbine

    DEFF Research Database (Denmark)

    Larsen, Torben J.; Kim, Taeseong

    2016-01-01

    In this paper the dynamics of a two-bladed turbine is investigated numerically as well as experimentally with respect to how the turbine frequencies change with the rotor speed. It is shown how the turbine frequencies of a two-bladed rotor change with the azimuthal position at standstill and how ...

  20. Fault diagnosis of a Wind Turbine Rotor using a Multi-blade Coordinate Framework

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2012-01-01

    Fault diagnosis of a wind turbine rotor is considered. The faults considered are sensor faults and blades mounted with a pitch offset. A fault at a single blade will result in asymmetries in the rotor, which can be applied for fault diagnosis. The diagnosis is derived by using the multiblade coor...

  1. Blade Displacement Measurements of the Full-Scale UH-60A Airloads Rotor

    Science.gov (United States)

    Barrows, Danny A.; Burner, Alpheus W.; Abrego, Anita I.; Olson, Lawrence E.

    2011-01-01

    Blade displacement measurements were acquired during a wind tunnel test of the full-scale UH-60A Airloads rotor. The test was conducted in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex at NASA Ames Research Center. Multi-camera photogrammetry was used to measure the blade displacements of the four-bladed rotor. These measurements encompass a range of test conditions that include advance ratios from 0.15 to unique slowed-rotor simulations as high as 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective of these measurements is to provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft computational tools. The methodology, system development, measurement techniques, and preliminary sample blade displacement measurements are presented.

  2. Study of casing treatment stall margin improvement phenomena. [for compressor rotor blade tips compressor blades rotating stalls

    Science.gov (United States)

    Prince, D. C., Jr.; Wisler, D. C.; Hilvers, D. E.

    1974-01-01

    The results of a program of experimental and analytical research in casing treatments over axial compressor rotor blade tips are presented. Circumferential groove, axial-skewed slot, and blade angle slot treatments were tested. These yielded, for reduction in stalling flow and loss in peak efficiency, 5.8% and 0 points, 15.3% and 2.0 points, and 15.0% and 1.2 points, respectively. These values are consistent with other experience. The favorable stalling flow situations correlated well with observations of higher-then-normal surface pressures on the rotor blade pressure surfaces in the tip region, and with increased maximum diffusions on the suction surfaces. Annular wall pressure gradients, especially in the 50-75% chord region, are also increased and blade surface pressure loadings are shifted toward the trailing edge for treated configurations. Rotor blade wakes may be somewhat thinner in the presence of good treatments, particularly under operating conditions close to the baseline stall.

  3. Flow Modification over Rotor Blade with Suction Boundary Layer Control Technique

    Directory of Open Access Journals (Sweden)

    Navneet Kumar

    2016-06-01

    Full Text Available The efficiency of transonic aircraft engines depend upon the performance of compressor rotor. To increase compressor rotors performance flow separation around rotor blades must be delayed and controlled. The aim was to control the flow separation of blades using suction boundary layer control method. Rotor blade has been modelled in designing software CATIA and then a suction surface has been created on blade and then import these geometries to ANSYS-CFX 14.5 for computational analysis of flow around blades. Suction slot has been applied at the trailing edge of suction surface and Shear stress transport model has been used for computational analysis. Two different suction mass flow rates 1 kg/s and 1.5 kg/s have been used here and boundary layer separation effects have been changed and this could be readily seen that the velocity vectors have reattached, preventing the boundary layer separation at the suction surface of the blade.

  4. An advanced stochastic model for threshold crossing studies of rotor blade vibrations.

    Science.gov (United States)

    Gaonkar, G. H.; Hohenemser, K. H.

    1972-01-01

    A stochastic model to analyze turbulence-excited rotor blade vibrations, previously described by Gaonkar et al. (1971), is generalized to include nonuniformity of the atmospheric turbulence velocity across the rotor disk in the longitudinal direction. The results of the presented analysis suggest that the nonuniformity of the vertical turbulence over the rotor disk is of little influence on the random blade flapping response, at least as far as longitudinal nonuniformity is concerned.

  5. Weight Assessment for Fuselage Shielding on Aircraft With Open-Rotor Engines and Composite Blade Loss

    Science.gov (United States)

    Carney, Kelly; Pereira, Michael; Kohlman, Lee; Goldberg, Robert; Envia, Edmane; Lawrence, Charles; Roberts, Gary; Emmerling, William

    2013-01-01

    The Federal Aviation Administration (FAA) has been engaged in discussions with airframe and engine manufacturers concerning regulations that would apply to new technology fuel efficient "openrotor" engines. Existing regulations for the engines and airframe did not envision features of these engines that include eliminating the fan blade containment systems and including two rows of counter-rotating blades. Damage to the airframe from a failed blade could potentially be catastrophic. Therefore the feasibility of using aircraft fuselage shielding was investigated. In order to establish the feasibility of this shielding, a study was conducted to provide an estimate for the fuselage shielding weight required to provide protection from an open-rotor blade loss. This estimate was generated using a two-step procedure. First, a trajectory analysis was performed to determine the blade orientation and velocity at the point of impact with the fuselage. The trajectory analysis also showed that a blade dispersion angle of 3deg bounded the probable dispersion pattern and so was used for the weight estimate. Next, a finite element impact analysis was performed to determine the required shielding thickness to prevent fuselage penetration. The impact analysis was conducted using an FAA-provided composite blade geometry. The fuselage geometry was based on a medium-sized passenger composite airframe. In the analysis, both the blade and fuselage were assumed to be constructed from a T700S/PR520 triaxially-braided composite architecture. Sufficient test data on T700S/PR520 is available to enable reliable analysis, and also demonstrate its good impact resistance properties. This system was also used in modeling the surrogate blade. The estimated additional weight required for fuselage shielding for a wing- mounted counterrotating open-rotor blade is 236 lb per aircraft. This estimate is based on the shielding material serving the dual use of shielding and fuselage structure. If the

  6. An investigation of the vibration characteristics of shrouded-bladed-disk rotor stages

    Science.gov (United States)

    Chen, L.-T.; Dugundji, J.

    1979-01-01

    Coupled differential equations of motion are given for application to a rotating, pretwisted and heated beam under the effects of thermal stresses and gas bending loads. The circumferential modes of the multi-blade vibration of a bladed-disk rotor stage were studied. A finite element method was developed for the dynamic and static deformation analysis of the blade. The deformations of a bladed disk and a shrouded-bladed disk were studied by introducing a special bladed-disk element and a special shrouded-blade element. Some features of the vibration of part-span-shrouded, bladed-disk rotor stages are discussed. The static deformation, thermal stress and gas bending effects on the blade vibration were presented previously.

  7. A multi-frequency fatigue testing method for wind turbine rotor blades

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Belloni, Federico; Tesauro, Angelo

    2017-01-01

    Rotor blades are among the most delicate components of modern wind turbines. Reliability is a crucial aspect, since blades shall ideally remain free of failure under ultra-high cycle loading conditions throughout their designated lifetime of 20–25 years. Full-scale blade tests are the most accura...

  8. EVALUATION OF PERFORMANCE OF HORIZONTAL AXIS WIND TURBINE BLADES BASED ON OPTIMAL ROTOR THEORY

    Directory of Open Access Journals (Sweden)

    Nitin Tenguria

    2011-01-01

    Full Text Available Wind energy is a very popular renewable energy resource. In order to increase the use of wind energy, it is important to develop wind turbine rotor with high rotations rates and power coefficient. In this paper, a method for the determination of the aerodynamic performance characteristics using NACA airfoils is given for three bladed horizontal axis wind turbine. Blade geometry is obtained from the best approximation of the calculated theoretical optimum chord and twist distribution of the rotating blade. Optimal rotor theory is used, which is simple enough and accurate enough for rotor design. In this work, eight different airfoils are used to investigate the changes in performance of the blade. Rotor diameter taken is 82 m which is the diameter of VESTAS V82-1.65MW. The airfoils taken are same from root to tip in every blade. The design lift coefficient taken is 1.1. A computer program is generated to automate the complete procedure.

  9. EVALUATION OF PERFORMANCE OF HORIZONTAL AXIS WIND TURBINE BLADES BASED ON OPTIMAL ROTOR THEORY

    Directory of Open Access Journals (Sweden)

    Nitin Tenguria

    2011-06-01

    Full Text Available Wind energy is a very popular renewable energy resource. In order to increase the use of wind energy, it is important to develop wind turbine rotor with high rotations rates and power coefficient. In this paper, a method for the determination of the aerodynamic performance characteristics using NACA airfoils is given for three bladed horizontal axis wind turbine. Blade geometry is obtained from the best approximation of the calculated theoretical optimum chord and twist distribution of the rotating blade. Optimal rotor theory is used, which is simple enough and accurate enough for rotor design. In this work, eight different airfoils are used to investigate the changes in performance of the blade. Rotor diameter taken is 82 m which is the diameter of VESTAS V82-1.65MW. The airfoils taken are same from root to tip in every blade. The design lift coefficient taken is 1.1. A computer program is generated to automate the complete procedure.

  10. The effect of the number of blades on wind turbine wake - a comparison between 2-and 3-bladed rotors

    Science.gov (United States)

    Mühle, Franz; Adaramola, Muyiwa S.; Sretran, Lars

    2016-09-01

    Due to cost benefit and weight reduction, 2-bladed wind turbines have the potential to become more important for offshore wind applications. In order to optimize the arrangement of wind turbines in wind farms and for accurate forecasts of the power production, a detailed knowledge of the wake flow is needed. In this study, three different rotors with varying number of blades and similar performance behaviour have been designed and manufactured using the 3dimensional (3D) printing technology. The performance characteristics of these rotors as well as their wake features are measured experimentally in wind tunnel tests and compared. The velocity deficit is seen to vary only insignificantly for the wakes in distances of 3D (where D is the rotor diameter), 5D and 7D behind the turbine. However, higher turbulence intensity levels are recorded in the wake of the 2-bladed rotors. This could have potential for a faster wake recovery and thus a narrower turbine spacing.

  11. 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

    or combined with commercially available ones, with its specific structural analysis approach (thin wall theory and finite element models using beam, shell or solid elements) and their preferable analysis type (linear or geometrical non-linear). Along with sectional mass and stiffness properties, the outcome...... 40%, depending on the property compared. Modelling details, e.g. load application on the numerical models and assumptions, e.g. type of analysis, lead to these differences. The paper covers these subjects, presenting the modelling uncertainty derived....... 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...

  12. 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.

  13. 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.

  14. A parametric study of blade vortex interaction noise for two, three, and four-bladed model rotors at moderate tip speeds Theory and experiment

    Science.gov (United States)

    Leighton, K. P.; Harris, W. L.

    1984-01-01

    An investigation of blade slap due to blade vortex interaction (BVI) has been conducted. This investigation consisted of an examination of BVI blade slap for two, three, and four-bladed model rotors at tip Mach numbers ranging from 0.20 to 0.50. Blade slap contours have been obtained for each configuration tested. Differences in blade slap contours, peak sound pressure level, and directivity for each configuration tested are noted. Additional fundamental differences, such as multiple interaction BVI, are observed and occur for only specific rotor blade configurations. The effect of increasing the Mach number on the BVI blade slap for various rotor blade combinations has been quantified. A peak blade slap Mach number scaling law is proposed. Comparison of measured BVI blade slap with theory is made.

  15. NRT Rotor Structural / Aeroelastic Analysis for the Preliminary Design Review

    Energy Technology Data Exchange (ETDEWEB)

    Ennis, Brandon Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Paquette, Joshua A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    This document describes the initial structural design for the National Rotor Testbed blade as presented during the preliminary design review at Sandia National Laboratories on October 28- 29, 2015. The document summarizes the structural and aeroelastic requirements placed on the NRT rotor for satisfactory deployment at the DOE/SNL SWiFT experimental facility to produce high-quality datasets for wind turbine model validation. The method and result of the NRT blade structural optimization is also presented within this report, along with analysis of its satisfaction of the design requirements.

  16. Ice accretion modeling for wind turbine rotor blades

    Energy Technology Data Exchange (ETDEWEB)

    Chocron, D.; Brahimi, T.; Paraschivoiu, I.; Bombardier, J.A. [Ecole Polytechnique de Montreal (Canada)

    1997-12-31

    The increasing application of wind energy in northern climates implies operation of wind turbines under severe atmospheric icing conditions. Such conditions are well known in the Scandinavian countries, Canada and most of Eastern European countries. An extensive study to develop a procedure for the prediction of ice accretion on wind turbines rotor blades appears to be essential for the safe and economic operation of wind turbines in these cold regions. The objective of the present paper is to develop a computer code capable of simulating the shape and amount of ice which may accumulate on horizontal axis wind turbine blades when operating in icing conditions. The resulting code is capable to predict and simulate the formation of ice in rime and glaze conditions, calculate the flow field and particle trajectories and to perform thermodynamic analysis. It also gives the possibility of studying the effect of different parameters that influence ice formation such as temperature, liquid water content, droplet diameter and accretion time. The analysis has been conducted on different typical airfoils as well as on NASA/DOE Mod-0 wind turbine. Results showed that ice accretion on wind turbines may reduce the power output by more than 20%.

  17. Summary of Full-Scale Blade Displacement Measurements of the UH- 60A Airloads Rotor

    Science.gov (United States)

    Abrego, Anita I.; Meyn, Larry; Burner, Alpheus W.; Barrows, Danny A.

    2016-01-01

    Blade displacement measurements using multi-camera photogrammetry techniques were acquired for a full-scale UH-60A rotor, tested in the National Full-Scale Aerodynamic Complex 40-Foot by 80-Foot Wind Tunnel. The measurements, acquired over the full rotor azimuth, encompass a range of test conditions that include advance ratios from 0.15 to 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective was to measure the blade displacements and deformations of the four rotor blades and provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft prediction techniques. An overview of the blade displacement measurement methodology, system development, and data analysis techniques are presented. Sample results based on the final set of camera calibrations, data reduction procedures and estimated corrections that account for registration errors due to blade elasticity are shown. Differences in blade root pitch, flap and lag between the previously reported results and the current results are small. However, even small changes in estimated root flap and pitch can lead to significant differences in the blade elasticity values.

  18. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME ONE: PRELIMINARY DESIGN REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.; Chow, Ray [Zimitar, Inc.; Nordenholz, Thomas R. [The California Maritime Academy; Wamble, John Lee [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  19. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME TWO: INNOVATION & COST OF ENERGY

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  20. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME ZERO: OVERVIEW AND COMMERCIAL PATH

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  1. HIGH EFFICIENCY STRUCTURAL FLOWTHROUGH ROTOR WITH ACTIVE FLAP CONTROL: VOLUME THREE: MARKET & TEAM

    Energy Technology Data Exchange (ETDEWEB)

    Zuteck, Michael D. [Zimitar, Inc.; Jackson, Kevin L. [Zimitar, Inc.; Santos, Richard A. [Zimitar, Inc.

    2015-05-16

    The Zimitar one-piece rotor primary structure is integrated, so balanced thrust and gravity loads flow through the hub region without transferring out of its composite material. Large inner rotor geometry is used since there is no need to neck down to a blade root region and pitch bearing. Rotor control is provided by a highly redundant, five flap system on each blade, sized so that easily handled standard electric linear actuators are sufficient.

  2. Blade Motion Correlation for the Full-Scale UH-60A Airloads Rotor

    Science.gov (United States)

    Romander, Ethan A.; Meyn, Larry A.; Barrows, Danny; Burner, Alpheus

    2014-01-01

    Testing was successfully completed in May 2010 on a full-scale UH-60A rotor system in the USAF's National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel.[1] The primary objective of this NASA Army sponsored test program was to acquire a comprehensive set of validation-quality measurements ona full-scale pressure-instrumented rotor system at conditions that challenge the most sophisticated modeling andsimulation tools. The test hardware included the same rotor blades used during the UH-60A Airloads flight test.[2] Key measurements included rotor performance, blade loads, blade pressures, blade displacements, and rotorwake measurements using large-field Particle Image Velocimetry (PIV) and Retro-reflective Background Oriented Schlieren (RBOS).

  3. CFD simulation of a 2 bladed multi megawatt wind turbine with flexible rotor connection

    Science.gov (United States)

    Klein, L.; Luhmann, B.; Rösch, K.-N.; Lutz, T.; Cheng, P.-W.; Krämer, E.

    2016-09-01

    An innovative passive load reduction concept for a two bladed 3.4 MW wind turbine is investigated by a conjoint CFD and MBS - BEM methodology. The concept consists of a flexible hub mount which allows a tumbling motion of the rotor. First, the system is simulated with a MBS tool coupled to a BEM code. Then, the resulting motion of the rotor is extracted from the simulation and applied on the CFD simulation as prescribed motion. The aerodynamic results show a significant load reduction on the support structure. Hub pitching and yawing moment amplitudes are reduced by more than 50% in a vertically sheared inflow. Furthermore, the suitability of the MBS - BEM approach for the simulation of the load reduction system is shown.

  4. The effect of blade pitch in the rotor hydrodynamics of a cross-flow turbine

    Science.gov (United States)

    Somoano, Miguel; Huera-Huarte, Francisco

    2016-11-01

    In this work we will show how the hydrodynamics of the rotor of a straight-bladed Cross-Flow Turbine (CFT) are affected by the Tip Speed Ratio (TSR), and the blade pitch angle imposed to the rotor. The CFT model used in experiments consists of a three-bladed (NACA-0015) vertical axis turbine with a chord (c) to rotor diameter (D) ratio of 0.16. Planar Digital Particle Image Velocimetry (DPIV) was used, with the laser sheet aiming at the mid-span of the blades, illuminating the inner part of the rotor and the near wake of the turbine. Tests were made by forcing the rotation of the turbine with a DC motor, which provided precise control of the TSR, while being towed in a still-water tank at a constant Reynolds number of 61000. A range of TSRs from 0.7 to 2.3 were covered for different blade pitches, ranging from 8° toe-in to 16° toe-out. The interaction between the blades in the rotor will be discussed by examining dimensionless phase-averaged vorticity fields in the inner part of the rotor and mean velocity fields in the near wake of the turbine. Supported by the Spanish Ministry of Economy and Competitiveness, Grant BES-2013-065366 and project DPI2015-71645-P.

  5. Blade Displacement Measurement Technique Applied to a Full-Scale Rotor Test

    Science.gov (United States)

    Abrego, Anita I.; Olson, Lawrence E.; Romander, Ethan A.; Barrows, Danny A.; Burner, Alpheus W.

    2012-01-01

    Blade displacement measurements using multi-camera photogrammetry were acquired during the full-scale wind tunnel test of the UH-60A Airloads rotor, conducted in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel. The objectives were to measure the blade displacement and deformation of the four rotor blades as they rotated through the entire rotor azimuth. These measurements are expected to provide a unique dataset to aid in the development and validation of rotorcraft prediction techniques. They are used to resolve the blade shape and position, including pitch, flap, lag and elastic deformation. Photogrammetric data encompass advance ratios from 0.15 to slowed rotor simulations of 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. An overview of the blade displacement measurement methodology and system development, descriptions of image processing, uncertainty considerations, preliminary results covering static and moderate advance ratio test conditions and future considerations are presented. Comparisons of experimental and computational results for a moderate advance ratio forward flight condition show good trend agreements, but also indicate significant mean discrepancies in lag and elastic twist. Blade displacement pitch measurements agree well with both the wind tunnel commanded and measured values.

  6. Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers

    Institute of Scientific and Technical Information of China (English)

    CAO DengQing; WANG LiGang; CHEN YuShu; HUANG WenHu

    2009-01-01

    To study the nonlinear dynamic behavior of the bladed overhang rotor system with squeeze film damper (SFD), a blade-overhang rotor-SFD model is formulated using the lumped mass method and the Lagrange approach. The cavitated short bearing model is employed to describe the nonlinear oil force of the SFD. To reduce the scale of the nonlinear coupling system, a set of orthogonal transformations is employed to decouple the one nodal diameter equations of blades, which are coupled with the dy-namical equations of the rotor, with other equations of blades. In this way, the original system with 16+4n (n≥3) degrees of freedom (DoF) is reduced to a system with 24 DoF only. Then the parametric excitation terms in the blade-overhang rotor-SFD model are simplified in terms of periodic transforma-tions. The coupling equations are numerically solved and the solutions are used to analyze the dy-trum plot. A variety of motion types are found such as multi-periodic, quasi-periodic, and chaotic mo-tions. Moreover, the typical nonlinear dynamic evolutions including the periodic-doubling bifurcation and reverse bifurcation are noted. It is noticed that there exist apparent differences in the dynamic behavior between the blade-overhang rotor-SFD models without and with considering the effect of blades.

  7. Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    To study the nonlinear dynamic behavior of the bladed overhang rotor system with squeeze film damper (SFD), a blade-overhang rotor-SFD model is formulated using the lumped mass method and the Lagrange approach. The cavitated short bearing model is employed to describe the nonlinear oil force of the SFD. To reduce the scale of the nonlinear coupling system, a set of orthogonal transformations is employed to decouple the one nodal diameter equations of blades, which are coupled with the dy- namical equations of the rotor, with other equations of blades. In this way, the original system with 16+4n (n≥3) degrees of freedom (DoF) is reduced to a system with 24 DoF only. Then the parametric excitation terms in the blade-overhang rotor-SFD model are simplified in terms of periodic transforma- tions. The coupling equations are numerically solved and the solutions are used to analyze the dy- namic behavior of the system in terms of the bifurcation diagram, whirl orbit, Poincaré map and spec- trum plot. A variety of motion types are found such as multi-periodic, quasi-periodic, and chaotic mo- tions. Moreover, the typical nonlinear dynamic evolutions including the periodic-doubling bifurcation and reverse bifurcation are noted. It is noticed that there exist apparent differences in the dynamic behavior between the blade-overhang rotor-SFD models without and with considering the effect of blades.

  8. Dynamic surface measurements on a model helicopter rotor during blade slap at high angles of attack

    Science.gov (United States)

    Hubbard, J. E., Jr.; Harris, W. L.

    1982-01-01

    The modern helicopter offers a unique operational capability to both the public and private sectors. However, the use of the helicopter may become severely limited due to the radiated noise generated by the rotor system. A description is presented of some of the experimental results obtained with a model helicopter rotor in an anechoic wind tunnel with regard to blade stall as a source mechanism of blade slap. Attention is given to dynamic rotor blade surface phenomena and the resulting far field impulsive noise from the model helicopter rotor at high angles of attack and low tip speed. The results of the investigation strongly implicates the boundary layer as playing an important role in blade slap due to blade/vortex interaction (BVI) in a highly loaded rotor. Intermittent stall cannot be ruled out as a possible source mechanism for blade slap. This implies that blade surface characteristics, airfoil shape and local Reynolds number may now be used as tools to reduce the resultant far-field sound pressure levels in helicopters.

  9. Panel/full-span free-wake coupled method for unsteady aerodynamics of helicopter rotor blade

    Institute of Scientific and Technical Information of China (English)

    Tan Jianfeng; Wang Haowen

    2013-01-01

    A full-span free-wake method is coupled with an unsteady panel method to accurately predict the unsteady aerodynamics of helicopter rotor blades in hover and forward flight.The unsteady potential-based panel method is used to consider aerodynamics of finite thickness multi-bladed rotors,and the full-span free-wake method is applied to simulating dynamics of rotor wake.These methods are tightly coupled through trailing-edge Kutta condition and by converting doublet-wake panels to full-span vortex filaments.A velocity-field integration technique is also adopted to overcome singularity problem during the interaction between the rotor wake and blades.Helicopter rotors including Caradonna-Tung,UH-60A,and AH-1G rotors,are simulated in hover and forward flight to validate the accuracy of this approach.The predicted aerodynamic loads of rotor blades agree well with available measured data and computational fluid dynamics (CFD) results,and the unsteady dynamics of rotor wake is also well simulated.Compared to CFD,the present method obtains accurate results more efficiently and is suitable to rotorcraft aeroelastic analysis.

  10. Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2003-01-01

    In rotor-blade systems basis as well as parametric vibration modes will appear due to the vibration coupling among flexible rotating blades and hub rigid body motion. Parametric vibration will typically occur when the hub operates at a constant angular velocity. Operating at constant velocity...

  11. Wireless sensor network for helicopter rotor blade vibration monitoring: Requirements definition and technological aspects

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Das, Kallol; Loendersloot, Richard; Tinga, Tiedo; Havinga, Paul; Basu, Biswajit

    2013-01-01

    The main rotor accounts for the largest vibration source for a helicopter fuselage and its components. However, accurate blade monitoring has been limited due to the practical restrictions on instrumenting rotating blades. The use of Wireless Sensor Networks (WSNs) for real time vibration monitoring

  12. Nonlinear blade element-momentum analysis of Betz-Goldstein rotors

    DEFF Research Database (Denmark)

    Wood, D. H.; Okulov, Valery

    2017-01-01

    •We analyze Betz-Goldstein (BG) rotors for maximum power at any tip speed ratio and number of blades.•We prove that Glauert's incorporation of tip loss in the blade torque and thrust equation are correct.•We show the nonlinear angular momentum terms can contribute 12% of the total torque....

  13. Extracting radar micro-Doppler signatures of helicopter rotating rotor blades using K-band radars

    Science.gov (United States)

    Chen, Rachel; Liu, Baokun

    2014-06-01

    Helicopter identification has been an attractive topic. In this paper, we applied radar micro-Doppler signatures to identify helicopter. For identifying the type of a helicopter, besides its shape and size, the number of blades, the length of the blade, and the rotation rate of the rotor are important features, which can be estimated from radar micro-Doppler signatures of the helicopter's rotating rotor blades. In our study, K-band CW/FMCW radars are used for collecting returned signals from helicopters. By analyzing radar micro-Doppler signatures, we can estimate the number of blades, the length of the blade, the angular rotation rate of the rotating blade, and other necessary parameters for identifying the type of a helicopter.

  14. Comparison of composite rotor blade models: A coupled-beam analysis and an MSC/NASTRAN finite-element model

    Science.gov (United States)

    Hodges, Robert V.; Nixon, Mark W.; Rehfield, Lawrence W.

    1987-01-01

    A methodology was developed for the structural analysis of composite rotor blades. This coupled-beam analysis is relatively simple to use compared with alternative analysis techniques. The beam analysis was developed for thin-wall single-cell rotor structures and includes the effects of elastic coupling. This paper demonstrates the effectiveness of the new composite-beam analysis method through comparison of its results with those of an established baseline analysis technique. The baseline analysis is an MSC/NASTRAN finite-element model built up from anisotropic shell elements. Deformations are compared for three linear static load cases of centrifugal force at design rotor speed, applied torque, and lift for an ideal rotor in hover. A D-spar designed to twist under axial loading is the subject of the analysis. Results indicate the coupled-beam analysis is well within engineering accuracy.

  15. Structural Health and Prognostics Management for Offshore Wind Turbines: Sensitivity Analysis of Rotor Fault and Blade Damage with O&M Cost Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Myrent, Noah J. [Vanderbilt Univ., Nashville, TN (United States). Lab. for Systems Integrity and Reliability; Barrett, Natalie C. [Vanderbilt Univ., Nashville, TN (United States). Lab. for Systems Integrity and Reliability; Adams, Douglas E. [Vanderbilt Univ., Nashville, TN (United States). Lab. for Systems Integrity and Reliability; Griffith, Daniel Todd [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Wind Energy Technology Dept.

    2014-07-01

    Operations and maintenance costs for offshore wind plants are significantly higher than the current costs for land-based (onshore) wind plants. One way to reduce these costs would be to implement a structural health and prognostic management (SHPM) system as part of a condition based maintenance paradigm with smart load management and utilize a state-based cost model to assess the economics associated with use of the SHPM system. To facilitate the development of such a system a multi-scale modeling and simulation approach developed in prior work is used to identify how the underlying physics of the system are affected by the presence of damage and faults, and how these changes manifest themselves in the operational response of a full turbine. This methodology was used to investigate two case studies: (1) the effects of rotor imbalance due to pitch error (aerodynamic imbalance) and mass imbalance and (2) disbond of the shear web; both on a 5-MW offshore wind turbine in the present report. Sensitivity analyses were carried out for the detection strategies of rotor imbalance and shear web disbond developed in prior work by evaluating the robustness of key measurement parameters in the presence of varying wind speeds, horizontal shear, and turbulence. Detection strategies were refined for these fault mechanisms and probabilities of detection were calculated. For all three fault mechanisms, the probability of detection was 96% or higher for the optimized wind speed ranges of the laminar, 30% horizontal shear, and 60% horizontal shear wind profiles. The revised cost model provided insight into the estimated savings in operations and maintenance costs as they relate to the characteristics of the SHPM system. The integration of the health monitoring information and O&M cost versus damage/fault severity information provides the initial steps to identify processes to reduce operations and maintenance costs for an offshore wind farm while increasing turbine availability

  16. Technology transfer between aircraft and rotor blade manufacturing; Technologietransfer zwischen Flugzeugbau und Rotorblattbau

    Energy Technology Data Exchange (ETDEWEB)

    Apmann, H. [Premium Aerotec GmbH (Germany)

    2011-02-15

    Aircraft construction and rotor blade production do have some basic things in common. Among these are the material to be processed, the dimensions, as well as the component requirements. Therefore, a possible technology exchange is obvious. Common points like the application of tools and handling units for fibre material, self-tempering systems, tolerance management, component and process development as well as transport assignments, demonstrate the common subjects, but also the differences of both areas. Therefore, both branches can learn from each other and profit from the respective experiences. An example of a successful cross-sectoral cooperation is shown. Curing tools made of steel for the production of rotor blade components have been generated on the basis of the experience and the existent know-how in the production systems area of Premium Aerotec GmbH (a worldwide leading supplier of aircraft structures). The essential advantages of such a steel-curing tool, like the faster heat transfer between heat- and cooling medium and component, higher stability time of the mould, more robust characteristics compared with loads etc. are shown in the production result. By the application of this tool, the production time of the components could be nearly halved. The given tolerances are kept and the process security is raised substantially. Due to the shorter production time the productivity is increased considerably and the growing requirements of the market can be met. Based on the example of this tool, which is used successfully in the serial production for rotor blade components, it's obvious how fast cross-sectoral experiences can lead to a common aim and success. On the basis of this experience further developments in the areas of tools, handling systems and process development are currently carried out. Among others, a new system for tempering of steel moulds, which at the same time will be equipped with a surface coating of the cover sheets, is being

  17. An Experimental Analysis of the Effect of Icing on Wind Turbine Rotor Blades

    DEFF Research Database (Denmark)

    Raja, Muhammad Imran; Hussain, Dil muhammed Akbar; Soltani, Mohsen

    2016-01-01

    are printed with 3D printer and tested one by one in a Wind Tunnel. Lift, drag and moment coefficients are calculated from the measured experimental data and program WT-Perf based on blade-element momentum (BEM) theory is used to predict the performance of wind turbine. Cp curves generated from the test......Wind Turbine is highly nonlinear plant whose dynamics changes with change in aerodynamics of the rotor blade. Power extracted from the wind turbine is a function of coefficient of power (Cp). Wind turbine installed in the cold climate areas has an icing on its rotor blade which might change its...

  18. Comparison of classical methods for blade design and the influence of tip correction on rotor performance

    Science.gov (United States)

    Sørensen, J. N.; Okulov, V. L.; Mikkelsen, R. F.; Naumov, I. V.; Litvinov, I. V.

    2016-09-01

    The classical blade-element/momentum (BE/M) method, which is used together with different types of corrections (e.g. the Prandtl or Glauert tip correction), is today the most basic tool in the design of wind turbine rotors. However, there are other classical techniques based on a combination of the blade-element approach and lifting-line (BE/LL) methods, which are less used by the wind turbine community. The BE/LL method involves different interpretations for rotors with finite or infinite numbers of blades and different assumptions with respect to the optimum circulation distribution. In the present study we compare the performance and the resulting design of the BE/M method by Glauert [1] and the BE/LL method by Betz [2] for finite as well as for infinite-bladed rotors, corrected for finiteness through the tip correction. In the first part of the paper, expressions are given for the optimum design, including blade plan forms and local pitch distributions. The comparison shows that the resulting geometry of the rotor depends on the method used, but that the differences mainly exist in the inner part of the blade and at relatively small tip speed ratios (TSRwater flume to compare their performance at different tip speed ratios and pitch angles. As a result of the comparison it was found that the Betz rotor had the best performance.

  19. A comparison between 2-and 3-bladed wind turbine rotors with focus on wake characteristics

    Science.gov (United States)

    Mühle, Franz; Adaramola, Muyiwa Samuel; Sætran, Lars

    2016-11-01

    Due to cost benefit and weight reduction, 2-bladed wind turbines have the potential to become more important for offshore wind applications. In order to optimize the arrangement of wind turbines in wind farms and for accurate forecasts of the power production, a detailed knowledge of the wake flow is needed. In the presented study, three different rotors with varying number of blades and similar performance behavior have been designed and manufactured using the 3-dimensional (3D) printing technology. The performance characteristics of these rotors as well as their wake features are measured experimentally in wind tunnel tests and compared. The velocity deficit is seen to vary only insignificantly for the wakes in distances of 3D (where D is the rotor diameter), 5D and 7D behind the turbine. However, higher turbulence intensity levels are recorded in the wake of the 2-bladed rotors. This could have potential for a faster wake recovery and thus a narrower turbine spacing.

  20. Optimum blade loading for a powered rotor in descent

    Institute of Scientific and Technical Information of China (English)

    Ramin Modarres; David A. Peters

    2016-01-01

    The optimum loading for rotors has previously been found for hover, climb and wind turbine conditions;but, up to now, no one has determined the optimum rotor loading in descent. This could be an important design consideration for rotary-wing parachutes and low-speed des-cents. In this paper, the optimal loading for a powered rotor in descent is found from momentum theory based on a variational principle. This loading is compared with the optimal loading for a rotor in hover or climb and with the Betz rotor loading (which is optimum for a lightly-loaded rotor). Wake contraction for each of the various loadings is also presented.

  1. A Study of Active Rotor-Blade Vibration Control using Electro-Magnetic Actuation - Part I: Theory

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2004-01-01

    This is the first paper in a two-part study on active rotor-blade vibration control. Blade faults are a major problem in bladed machines, such as turbines and compressors. Moreover, increasing demands for higher efficiency, lower weight and higher speed imply that blades become even more suscepti...

  2. A study of casing treatment stall margin improvement phenomena. [for axial compressor rotor blade tips

    Science.gov (United States)

    Prince, D. C., Jr.; Wisler, D. C.; Hilvers, D. E.

    1975-01-01

    The results of a program of experimental and analytical research in casing treatments over axial compressor rotor blade tips are presented. Circumferential groove, axial-skewed slot and blade angle slot treatments were tested at low speeds. With the circumferential groove treatment the stalling flow was reduced 5.8% at negligible efficiency sacrifice. The axial-skewed slot treatment improved the stalling flow by 15.3%; 1.8 points in peak efficiency were sacrificed. The blade angle slot treatment improved the stalling flow by 15.0%; 1.4 points in peak efficiency were sacrificed. The favorable stalling flow situations correlated well with observations of higher-than-normal surface pressures on the rotor blade pressure surfaces in the tip region, and with increased maximum diffusions on the suction surfaces. Annulus wall pressure gradients, especially in the 50 to 75% chord region, are also increased and blade surface pressure loadings are shifted toward the trailing edge for treated configurations.

  3. Fe Analysis of a Steam Turbine HP Rotor Blade Stage Concerning Material Effort, Dynamic Properties and Creep Damage Assessment

    Directory of Open Access Journals (Sweden)

    Borkowski Paweł

    2016-03-01

    Full Text Available This paper is concerned with the 1st stage of HP rotor blade assembly steam turbine TK 120. The methodology was focused on the selection of mechanical properties and the way of the rotor disc modeling and estimating the degree of damage caused by creep. Then the dynamic interference between the frequencies of excitation and the natural frequencies was assessed. Static calculations were performed for the cyclic sectors consisting of the disc, disc blades, spacers and shrouding, including loads as temperature, mass forces from the angular velocity and the pressure on the blades. Then, the creep analysis using a Norton’s model and the modal analysis were performed. Static analysis gave information concerning the distributions of displacements, stress and strain components. In the creep analysis, the creep displacements and stress relaxation versus time were determined and the estimated degree of damage caused by creep was evaluated at each part of the rotor disc. In the modal analysis, the natural frequencies and modes of vibrations corresponding to the nodal diameters were found. The results of modal analysis were shown in the SAFE graph. Numerical calculations have shown that the rotor disc was a well-designed structure and did not reveal any dynamic interference.

  4. Trailing Vortex Measurements in the Wake of a Hovering Rotor Blade with Various Tip Shapes

    Science.gov (United States)

    Martin, Preston B.; Leishman, J. Gordon

    2003-01-01

    This work examined the wake aerodynamics of a single helicopter rotor blade with several tip shapes operating on a hover test stand. Velocity field measurements were conducted using three-component laser Doppler velocimetry (LDV). The objective of these measurements was to document the vortex velocity profiles and then extract the core properties, such as the core radius, peak swirl velocity, and axial velocity. The measured test cases covered a wide range of wake-ages and several tip shapes, including rectangular, tapered, swept, and a subwing tip. One of the primary differences shown by the change in tip shape was the wake geometry. The effect of blade taper reduced the initial peak swirl velocity by a significant fraction. It appears that this is accomplished by decreasing the vortex strength for a given blade loading. The subwing measurements showed that the interaction and merging of the subwing and primary vortices created a less coherent vortical structure. A source of vortex core instability is shown to be the ratio of the peak swirl velocity to the axial velocity deficit. The results show that if there is a turbulence producing region of the vortex structure, it will be outside of the core boundary. The LDV measurements were supported by laser light-sheet flow visualization. The results provide several benchmark test cases for future validation of theoretical vortex models, numerical free-wake models, and computational fluid dynamics results.

  5. A Study of Active Rotor-Blade Vibration Control using Electro-Magnetic Actuation - Part II: Experiment

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2004-01-01

    . The remaining two sets of actuators are applied to act directly onto the hub, working as an active radial bearing controlling the rotor lateral movement. The rig is equipped with sensors measuring blade and rotor vibrations. Actuators and sensors are connected to a digital signal processor running the control......This is the second paper in a two-part study on active rotor-blade vibration control. This part presents an experimental contribution into the work of active controller design for rotor-blade systems. The primary aim is to give an experimental validation and show the applicability...... shaft is mounted in a flexible hub, which can perform lateral movement. The blades are designed as simple Euler-Bernoulli beams with tip masses in order to increase the vibration coupling among the rigid rotors and the flexible blades motion. Different schemes of blade configurations, with and without...

  6. Investigation of Blade-row Flow Distributions in Axial-flow-compressor Stage Consisting of Guide Vanes and Rotor-blade Row

    Science.gov (United States)

    Mahoney, John J; Dugan, Paul D; Budinger, Raymond E; Goelzer, H Fred

    1950-01-01

    A 30-inch tip-diameter axial-flow compressor stage was investigated with and without rotor to determine individual blade-row performance, interblade-row effects, and outer-wall boundary-layer conditions. Velocity gradients at guide-vane outlet without rotor approximated design assumptions, when the measured variation of leaving angle was considered. With rotor in operation, Mach number and rotor-blade effects changed flow distribution leaving guide vanes and invalidated design assumption of radial equilibrium. Rotor-blade performance correlated interpolated two-dimensional results within 2 degrees, although tip stall was indicated in experimental and not two-dimensional results. Boundary-displacement thickness was less than 1.0 and 1.5 percent of passage height after guide vanes and after rotor, respectively, but increased rapidly after rotor when tip stall occurred.

  7. DESIGN OF TWO-DIMENSIONAL SUPERSONIC TURBINE ROTOR BLADES WITH BOUNDARY-LAYER CORRECTION

    Science.gov (United States)

    Goldman, L. J.

    1994-01-01

    A computer program has been developed for the design of supersonic rotor blades where losses are accounted for by correcting the ideal blade geometry for boundary layer displacement thickness. The ideal blade passage is designed by the method of characteristics and is based on establishing vortex flow within the passage. Boundary-layer parameters (displacement and momentum thicknesses) are calculated for the ideal passage, and the final blade geometry is obtained by adding the displacement thicknesses to the ideal nozzle coordinates. The boundary-layer parameters are also used to calculate the aftermixing conditions downstream of the rotor blades assuming the flow mixes to a uniform state. The computer program input consists essentially of the rotor inlet and outlet Mach numbers, upper- and lower-surface Mach numbers, inlet flow angle, specific heat ratio, and total flow conditions. The program gas properties are set up for air. Additional gases require changes to be made to the program. The computer output consists of the corrected rotor blade coordinates, the principal boundary-layer parameters, and the aftermixing conditions. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 7094. This program was developed in 1971.

  8. Some issues on modeling atmospheric turbulence experienced by helicopter rotor blades

    Science.gov (United States)

    Costello, Mark; Gaonkar, G. H.; Prasad, J. V. R.; Schrage, D. P.

    1992-01-01

    The atmospheric turbulence velocities seen by nonrotating aircraft components and rotating blades can be substantially different. The differences are due to the spatial motion of the rotor blades, which move fore and aft through the gust waves. Body-fixed atmospheric turbulence refers to the actual atmospheric turbulence experienced by a point fixed on a nonrotating aircraft component such as the aircraft's center of gravity or the rotor hub, while blade-fixed atmospheric turbulence refers to the atmospheric turbulence experienced by an element of the rotating rotor blade. An example is presented, which, though overly simplified, shows important differences between blade- and body-fixed rotorcraft atmospheric turbulence models. All of the information necessary to develop the dynamic equations describing the atmospheric turbulence velocity field experienced by an aircraft is contained in the atmospheric turbulence velocity correlation matrix. It is for this reason that a generalized formulation of the correlation matrix describing atmospheric turbulence that a rotating blade encounters is developed. From this correlation matrix, earlier treated cases restricted to a rotor flying straight and level directly into the mean wind can be recovered as special cases.

  9. Study of the Effect of Centrifugal Force on Rotor Blade Icing Process

    Directory of Open Access Journals (Sweden)

    Zhengzhi Wang

    2017-01-01

    Full Text Available In view of the rotor icing problems, the influence of centrifugal force on rotor blade icing is investigated. A numerical simulation method of three-dimensional rotor blade icing is presented. Body-fitted grids around the rotor blade are generated using overlapping grid technology and rotor flow field characteristics are obtained by solving N-S equations. According to Eulerian two-phase flow, the droplet trajectories are calculated and droplet impingement characteristics are obtained. The mass and energy conservation equations of ice accretion model are established and a new calculation method of runback water mass based on shear stress and centrifugal force is proposed to simulate water flow and ice shape. The calculation results are compared with available experimental results in order to verify the correctness of the numerical simulation method. The influence of centrifugal force on rotor icing is calculated. The results show that the flow direction and distribution of liquid water on rotor surfaces change under the action of centrifugal force, which lead to the increasing of icing at the stagnation point and the decreasing of icing on both frozen limitations.

  10. 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.

  11. Overall and blade element performance of a 1.20 pressure ratio fan stage with rotor blades reset -7 deg

    Science.gov (United States)

    Lewis, G. W., Jr.; Kovich, G.

    1976-01-01

    A 51-cm-diam model of a fan stage for short haul aircraft was tested in a single stage compressor research facility. The rotor blades were set 7 deg toward the axial direction (opened) from the design setting angle. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed and a weight flow of 30.9 kg/sec, the stage pressure ratio and efficiency were 1.205 and 0.85, respectively. The design speed rotor peak efficiency of 0.90 occurred at a flow rate of 32.5 kg/sec.

  12. Effect of blade loading and rotor speed on the optimal aerodynamic performance of wind turbine blades

    Science.gov (United States)

    Bryson, Christopher; Hussain, Fazle; Barhorst, Alan

    2015-11-01

    Optimization of wind turbine torque as a function of angle of attack - over the entire speed range from start-up to cut-off - is studied by considering the full trigonometric relations projecting lift and drag to thrust and torque. Since driving force and thrust are geometrically constrained, one cannot be changed without affecting the other. Increasing lift to enhance torque simultaneously increases thrust, which subsequently reduces the inflow angle with respect to the rotor plane via an increased reduction in inflow velocity. Reducing the inflow angle redirects the lift force away from the driving force generating the torque, which may reduce overall torque. Similarly, changes in the tip-speed ratio (TSR) affect the inflow angle and thus the optimal torque. Using the airfoil data from the NREL 5 MW reference turbine, the optimal angle of attack over the operational TSR range (4 to 15) was computed using a BEM model to incorporate the dynamic coupling, namely the interdependency of blade loading and inflow angle. The optimal angle of attack is close to minimum drag during start-up phase (high TSR) and continuously increases toward maximum lift at high wind speeds (low TSR).

  13. Blade Parameterization and Aerodynamic Design Optimization for a 3D Transonic Compressor Rotor

    Institute of Scientific and Technical Information of China (English)

    Naixing Chen; Hongwu Zhang; Yanji Xu; Weiguang Huang

    2007-01-01

    The present paper describes an optimization methodology for aerodynamic design of turbomachinery combined with a rapid 3D blade and grid generator (RAPID3DGRID), a N.S. solver, a blade parameterization method (BPM), a gradient-based parameterization-analyzing method (GPAM), a response surface method (RSM) with zooming algorithm and a simple gradient method. By the use of blade parameterization method a transonic compressor rotor can be expressed by a set of polynomials, and then it enables us to transform coordinate-expressed blade data to parameter-expressed and then to reduce the number of parameters. With changing any one of the parameters and by applying grid generator and N.S. solver, we can obtain several groups of samples. Here only ten parameters were considered to search an optimized compressor rotor. As a result of optimization, the adiabatic efficiency was increased by 1.73%.

  14. Data Summary Report for the Open Rotor Propulsion Rig Equipped With F31/A31 Rotor Blades

    Science.gov (United States)

    Stephens, David

    2014-01-01

    An extensive wind tunnel test campaign was undertaken to quantify the performance and acoustics of a counter-rotating open rotor system. The present document summarizes the portion of this test performed with the so-called Historical Baseline rotor blades, designated F31A31. It includes performance and acoustic data acquired at Mach numbers from take-off to cruise. It also includes the effect of propulsor angle of attack as well as an upstream pylon. This report is accompanied by an electronic data set including relevant acoustic and performance measurements for all of the F31A31 data.

  15. Random gust response statistics for coupled torsion-flapping rotor blade vibrations.

    Science.gov (United States)

    Gaonkar, G. H.; Hohenemser, K. H.; Yin, S. K.

    1972-01-01

    An analysis of coupled torsion-flapping rotor blade vibrations in response to atmospheric turbulence revealed that at high rotor advance ratios anticipated for future high speed pure or convertible rotorcraft both flapping and torsional vibrations can be severe. While appropriate feedback systems can alleviate flapping, they have little effect on torsion. Dynamic stability margins have also no substantial influence on dynamic torsion loads. The only effective means found to alleviate turbulence caused torsional vibrations and loads at high advance ratio was a substantial torsional stiffness margin with respect to local static torsional divergence of the retreating blade.

  16. A rotor-mounted digital instrumentation system for helicopter blade flight research measurements

    Science.gov (United States)

    Knight, V. H., Jr.; Haywood, W. S., Jr.; Williams, M. L.

    1978-01-01

    A rotor mounted flight instrumentation system developed for helicopter rotor blade research is described. The system utilizes high speed digital techniques to acquire research data from miniature pressure transducers on advanced rotor airfoils which are flight tested on an AH-1G helicopter. The system employs microelectronic pulse code modulation (PCM) multiplexer digitizer stations located remotely on the blade and in a hub mounted metal canister. As many as 25 sensors can be remotely digitized by a 2.5 mm thick electronics package mounted on the blade near the tip to reduce blade wiring. The electronics contained in the canister digitizes up to 16 sensors, formats these data with serial PCM data from the remote stations, and transmits the data from the canister which is above the plane of the rotor. Data are transmitted over an RF link to the ground for real time monitoring and to the helicopter fuselage for tape recording. The complete system is powered by batteries located in the canister and requires no slip rings on the rotor shaft.

  17. Study of the capacitance technique for measuring high-temperature blade tip clearance on ceramic rotors

    Science.gov (United States)

    Barranger, John P.

    1993-01-01

    Higher operating temperatures required for increased engine efficiency can be achieved by using ceramic materials for engine components. Ceramic turbine rotors are subject to the same limitations with regard to gas path efficiency as their superalloy predecessors. In this study, a modified frequency-modulation system is proposed for the measurement of blade tip clearance on ceramic rotors. It is expected to operate up to 1370 C (2500 F), the working temperature of present engines with ceramic turbine rotors. The design of the system addresses two special problems associated with nonmetallic blades: the capacitance is less than that of a metal blade and the effects of temperature may introduce uncertainty with regard to the blade tip material composition. To increase capacitance and stabilize the measurement, a small portion of the rotor is modified by the application of 5-micron-thick platinum films. The platinum surfaces on the probe electrodes and rotor that are exposed to the high-velocity gas stream are coated with an additional 10-micron-thick protective ceramic topcoat. A finite-element method is applied to calculate the capacitance as a function of clearance.

  18. Study to Improve Turbine Engine Rotor Blade Containment

    Science.gov (United States)

    1977-08-01

    compressor stages, two low turbine stages, two high turbine stages, and two intershaft locations. The clearance at each possible ub location was aet to...for a fan rotor failure which were: engine mounts, low rotor bearings and bearing supports, fan coupling nut, low shaft, low turbine tierods, and all

  19. Dynamic-stall and structural-modeling effects on helicopter blade stability with experimental correlation

    Science.gov (United States)

    Barwey, D.; Gaonkar, Gopal H.

    1994-04-01

    The effects of blade and root-flexure elasticity and dynamic stall on the stability of hingeless rotor blades are investigated. The dynamic stall description is based on the ONERA models of lift, drag, and pitching moment. The structural analysis is based on three blade models that range from a rigid flap-lag model to two elastic flap-lag-torsion models, which differ in representing root-flexure elasticity. The predictions are correlated with the measured lag damping of an experimental isolated three-blade rotor; the correlation covers rotor operations from near-zero-thrust conditions in hover to highly stalled, high-thrust conditions in foward flight. That correlation shows sensitivity of lag-damping predictions to structural refinements in blade and root-flexure modeling. Moreover, this sensitivity increases with increasing control pitch angle and advance ratio. For high-advance-ratio and high-thrust conditions, inclusion of dynamic stall generally improves the correlation.

  20. Sound generation by non-synchronously oscillating rotor blades in turbomachinery

    Science.gov (United States)

    Zhou, Di; Wang, Xiaoyu; Chen, Jun; Jing, Xiaodong; Sun, Xiaofeng

    2015-10-01

    In this paper, the sound generation by non-synchronously oscillating rotor blades in axial compressor is investigated with emphasis on establishing an analytical model for the corresponding sound field inside an annular duct. In terms of the present model, it is found that the acoustic frequency and propagating modes generated by non-synchronously oscillating rotor blades are not only associated with the blade vibration frequency and rotational speed, but also depend on the cascade inter-blade phase angle (IBPA) and the interaction between blades, which is clearly distinguished from typical Doppler effect. Moreover, it is also shown that although the IBPA of cascade is non-constant practically, the characteristics of sound generation are only slightly affected. Besides, the present work has conducted experimental investigations in order to gain insight into the generation mechanism of such complex sound field. Excellent agreement between the model prediction and experimental measurement in the near and far fields is generally observed in the circumstances with different parameter settings. Since the present study links the sound generation with blade oscillation, it would be very helpful to the fault diagnosis of rotor non-synchronous oscillation to some extent.

  1. Foreign Object Damage to Fan Rotor Blades of Aeroengine Part Ⅱ: Numerical Simulation of Bird Impact

    Institute of Scientific and Technical Information of China (English)

    Guan Yupu; Zhao Zhenhua; Chen Wei; Gao Deping

    2008-01-01

    Bird impact is one of the most dangerous threats to flight safety. The consequences of bird impact can be severe and, therefore, the aircraft components have to be certified for a proven level of bird impact resistance before being put into service. The fan rotor blades of aeroengine are the components being easily impacted by birds. It is necessary to ensure that the fan rotor blades should have adequate resistance against the bird impact, to reduce the flying accidents caused by bird impacts. Using the contacting-impacting algorithm, the numerical simulation is carried out to simulate bird impact. A three-blade computational model is set up for the fan rotor blade having shrouds. The transient response curves of the points corresponding to measured points in experiments, displacements and equivalent stresses on the blades are obtained during the simulation. From the comparison of the transient response curves obtained from numerical simulation with that obtained from experiments, it can be found that the variations in measured points and the corresponding points of simulation are basically the same. The deforming process, the maximum displacements and the maximum equivalent stresses on blades are analyzed. The numerical simulation verifies and complements the experiment results.

  2. Refined Betz limit for rotors with a finite number of blades

    DEFF Research Database (Denmark)

    Okulov, Valery; Sørensen, Jens Nørkær

    2008-01-01

    coefficient. Especially, they fail to reproduce the results of the general momentum theory when the number of blades goes to infinity. The present theory is a modification to the original model of Goldstein using a new analytical solution to the wake vortex problem. In contrast to earlier models, the new......The criterion of Betz for optimum rotors with a finite number of blades is revisited and used to determine the performance of wind turbines. The Betz criterion states that ideal efficiency is obtained when the distribution of circulation along the blade produces a rigidly helicoid wake that moves...

  3. Flight Adaptive Blade for Optimum Rotor Response (FABFORR) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — While past research has demonstrated the utility and benefits to be gained with the application of advanced rotor system control concepts, none have been implemented...

  4. Flight Adaptive Blade for Optimum Rotor Response (FABFORR) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — While past research has demonstrated the utility and benefits to be gained with the application of advanced rotor system control concepts, none have been...

  5. Fatigue life prediction and strength degradation of wind turbine rotor blade composites

    NARCIS (Netherlands)

    Nijssen, R.P.L.

    2006-01-01

    Wind turbine rotor blades are subjected to a large number of highly variable loads, but life predictions are typically based on constant amplitude fatigue behaviour. Therefore, it is important to determine how service life under variable amplitude fatigue can be estimated from constant amplitude fat

  6. Artificial Icing Test CH-47C Helicopter with Fiberglass Rotor Blades.

    Science.gov (United States)

    1979-07-01

    fiberglass rotor blades and the intake and exhaust ports for the prototype de-ice system generator . The following general aircraft information is...shut off valve was provided in the tubing run to the generator set fuel inlet. 22 0~0 zgI ogoo j 000 LiJ 2I Photo 3. De-ice System Generator Installation

  7. 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 t

  8. Comparison of classical methods for blade design and the influence of tip correction on rotor performance

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Okulov, Valery; Mikkelsen, Robert Flemming

    2016-01-01

    The classical blade-element/momentum (BE/M) method, which is used together with different types of corrections (e.g. the Prandtl or Glauert tip correction), is today the most basic tool in the design of wind turbine rotors. However, there are other classical techniques based on a combination...

  9. An Examination of a Pumping Rotor Blade Design for Brownout Mitigation

    Science.gov (United States)

    2015-05-18

    negative thrust effect was mathe - 70 matically removed, all pumping blade designs were found to exhibit similar perfor- mance characteristics. 2. When the...Pneumodynamic Characteristics of a Circulation Control Rotor Model,” 2nd Decennial Specialist ’ Meeting on Ro- torcraft Dynamics, NASA Ames Research

  10. Vibration reduction in helicopter rotors using an active control surface located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1992-01-01

    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  11. Vibration reduction in helicopter rotors using an active control surface located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1992-01-01

    A feasibility study of vibration reduction in a four-bladed helicopter rotor using individual blade control (IBC), which is implemented by an individually controlled aerodynamic surface located on each blade, is presented. For this exploratory study, a simple offset-hinged spring restrained model of the blade is used with fully coupled flap-lag-torsional dynamics for each blade. Deterministic controllers based on local and global system models are implemented to reduce 4/rev hub loads using both an actively controlled aerodynamic surface on each blade as well as conventional IBC, where the complete blade undergoes cyclic pitch change. The effectiveness of the two approaches for simultaneous reduction of the 4/rev hub shears and hub moments is compared. Conventional IBC requires considerably more power to achieve approximately the same level of vibration reduction as that obtained by implementing IBC using an active control surface located on the outboard segment of the blade. The effect of blade torsional flexibility on the vibration reduction effectiveness of the actively controlled surface was also considered and it was found that this parameter has a very substantial influence.

  12. 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.

  13. Numerical analysis on noise of rotor with unconventional blade tips based on CFD/Kirchhoff method

    Institute of Scientific and Technical Information of China (English)

    Wang Bo; Zhao Qijun; Xu Guohua; Ye Liang; Wang Junyi

    2013-01-01

    A solver is developed aiming at efficiently predicting rotor noise in hover and forward flight.In this solver,the nonlinear near-field solutions are calculated by a hybrid approach which includes the Navier-Stokes and Euler equations based on a moving-embedded grid system and adaptive grid methodology.A combination of the third-order upwind scheme and flux-difference splitting scheme,instead of the second-order center-difference scheme which may cause larger wake dissipation,has been employed in the present computational fluid dynamics (CFD) method.The sound pressure data in the near field can be calculated directly by solving the Navier-Stokes equations,and the sound propagation can be predicted by the Kirchhoffmethod.A harmonic expansion approach is presented for rotor far-field noise prediction,which gives an analytical expression for the integral function in the Kirchhoff formula.As a result,the interpolation process is simplified and the efficiency and accuracy of the interpolation are improved.Then,the high-speed impulsive (HIS) noise of a helicopter rotor at different tip Mach numbers and on different observers is calculated and analyzed in hover and forward flight,which shows a highly directional characteristic of the rotor HIS noise with a maximum value in the rotor plane,and the HSI noise weakens rapidly with the increasing of the directivity angle.In order to investigate the effects of the rotor blade-tip shape on its aeroacoustic characteristics,four kinds of blade tips are designed and their noise characteristics have been simulated.At last,a new unconventional CLOR-Ⅱ blade tip has been designed,and the noise characteristics of the presented CLOR-Ⅱ model rotor have been simulated and measured compared to the reference rotors with a rectangular or swept-back platform blade tip.The results demonstrate that the unconventional CLOR-Ⅱblade tip can significantly reduce the HSI noise of a rotor.

  14. An experimental study on self-output-control characteristics of micro downwind rotor with coning soft blades

    Institute of Scientific and Technical Information of China (English)

    EGUCHI; Hidenori; YOSHIDA; Kouichi; NISHI; Michihiro

    2010-01-01

    In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blades of 0.15 m chord whose material is light,soft and pliable foam plastic for perfect safety.From the wind tunnel test,it is realized that the performance is manageable by the coning angle of the rotor blade.In the present case,an improvement of the performance in lower wind speeds is achieved by using the coning blade of 20°.Besides,owing to the torsional deformation of very soft blade,the self-power control characteristic is observed in every test rotor regardless of coning angle in the range of 0°-20° under the wind speed less than 12 m/s.

  15. MEASUREMENTS OF PRESSURE DISTRIBUTIONS ON A ROTOR BLADE USING PSP TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Kidong Kim

    2011-12-01

    Full Text Available Surface pressure distributions on a rotating blade were measured by using pressure sensitive paint (PSP to understand aerodynamic characteristics of a rotor blade. The present study was conducted to investigate the PSP techniques for measuring the pressure distributions on a rotor blade. In order to perform the experiment, the PSP was required to response very fast due to rapid pressure fluctuations on a rotor blade. High energy excitation light source was also needed to acquire proper intensity images in a short excitation time. The techniques were based on a lifetime method. Qualitative pressure distributions on an upper surface of small scale rotor in hovering condition were measured as a preliminary experiment prior to forward flight conditions in the KARI low speed wind tunnel laboratory. From measured pressure distributions, striking pressure gradient was observed on an upper surface of rotor blade and the resulting pressure showed expected gradient depending on different collective pitch angles. ABSTRAK : Pengagihan tekanan permukaan ke atas berbilah putar disukat menggunakan cat sensitive tekanan (pressure sensitive paint (PSP untuk memahami sifat-sifat aerodinamik suatu berbilah putar. Kajian telah dijalankan untuk menyelidik teknik-teknik PSP dengan mengukur agihan tekanan ke atas suatu berbilah putar. Agar eksperimen dapat dijalankan dengan baik, PSP harus bertindak cepat kerana tekanan naik turun dengan pantas ke atas berbilah putar. Sumber cahaya ujaan tenaga tinggi diperlukan untuk mendapatkan imej keamatan wajar dalam jangka masa ujaan yang pendek. Teknik-teknik tersebut terhasil daripada kajian semasa hayat. Agihan tekanan kualitatif ke permukaan atas berskala kecil pemutar dalam keadaan mengapung diukur sebagai permulaan eksperimen, sebelum penerbangan kehadapan dalam makmal terowong angin laju rendah KARI. Daripada agihan tekanan yang disukat, kecerunan tekanan yang ketara diperolehi daripada permerhatian terhadap permukaan

  16. A multi-frequency fatigue testing method for wind turbine rotor blades

    Science.gov (United States)

    Eder, M. A.; Belloni, F.; Tesauro, A.; Hanis, T.

    2017-02-01

    Rotor blades are among the most delicate components of modern wind turbines. Reliability is a crucial aspect, since blades shall ideally remain free of failure under ultra-high cycle loading conditions throughout their designated lifetime of 20-25 years. Full-scale blade tests are the most accurate means to experimentally simulate damage evolution under operating conditions, and are therefore used to demonstrate that a blade type fulfils the reliability requirements to an acceptable degree of confidence. The state-of-the-art testing method for rotor blades in industry is based on resonance excitation where typically a rotating mass excites the blade close to its first natural frequency. During operation the blade response due to external forcing is governed by a weighted combination of its eigenmodes. Current test methodologies which only utilise the lowest eigenfrequency induce a fictitious damage where additional tuning masses are required to recover the desired damage distribution. Even with the commonly adopted amplitude upscaling technique fatigue tests remain a time-consuming and costly endeavour. The application of tuning masses increases the complexity of the problem by lowering the natural frequency of the blade and therefore increasing the testing time. The novel method presented in this paper aims at shortening the duration of the state-of-the-art fatigue testing method by simultaneously exciting the blade with a combination of two or more eigenfrequencies. Taking advantage of the different shapes of the excited eigenmodes, the actual spatial damage distribution can be more realistically simulated in the tests by tuning the excitation force amplitudes rather than adding tuning masses. This implies that in portions of the blade the lowest mode is governing the damage whereas in others higher modes contribute more significantly due to their higher cycle count. A numerical feasibility study based on a publicly available large utility rotor blade is used to

  17. Power harvesting using piezomaterial in a helicopter rotor blade

    NARCIS (Netherlands)

    Jong, de P.H.; Boer, de A.; Loendersloot, R.; Hoogt, van der P.J.M.

    2010-01-01

    Current power harvesting research has focused on bending beams and determining power output under a given excitation. For the European CleanSky – Green Rotor Craft project a tool is being developed which optimizes the piezoelectric material and placement thereof for power harvesting. It focuses on b

  18. Study to Improve Airframe Turbine Engine Rotor Blade Containment

    Science.gov (United States)

    1977-07-01

    high turbine, and low turbine were determined.* It was assumed that multiple blade fragments behaved as a single mass equivalent to the mass sum of all...case in the low turbine area generally produces detectable noise, thrust losses and vibration and in all probability the engine would be shut down

  19. Experimental investigation of helicopter vibration reduction using rotor blade aeroelastic tailoring

    Science.gov (United States)

    Wilbur, Matthew L.

    1991-01-01

    A wind tunnel investigation has been conducted to parametrically investigate the effect of blade nonstructural mass on helicopter fixed- and rotating-system vibratory loads. The data were obtained using Mach- and aeroelastically-scaled model rotor blades which allowed for the addition of concentrated nonstructural masses at multiple points along the blade radius. Testing was conducted for advance ratios ranging from 0.10 to 0.35 for ten blade mass configurations. Three thrust levels were obtained at representative full-scale shaft angles for each configuration. Results indicate that proper placement of blade nonstructural mass can provide reductions in fixed-system vibratory loads, but that correct mass placement and the loads reduction realized are dependent upon flight condition. The data base obtained with this investigation provides a comprehensive set of fixed-system shears and moments, blade moment, and blade flap and lag response. The data set is well suited for use in the correlation and development of advanced rotorcraft analyses.

  20. The Torsional Vibration of Turbo Axis Induced by Unsteady Aerodynamic Force on Rotor blade

    Institute of Scientific and Technical Information of China (English)

    ChenZuoyi; WuXiaofeng

    1998-01-01

    An algorithm for computing the 3-D oscillating flow field of the balde passage under the torsional vibration of the rotor is applied to analyze the stability in turbomachines.The induced flow field responding to blade vibration is computed by Oscillating Fluid Mechanics Method and parametric Polynomial Method.After getting the solution of the unsteady flow field,the work done by the unsteay aerodynamic force acting on the blade can be obtained.The negative or positive work is the criterion of the aeroelastic stability.Numerical results indicate that there are instabilities of the torsional vibration in some frequency bands.

  1. Antifreeze coatings for rotor blades of wind turbines - Final report; Antifreeze Beschichtungen fuer Rotorblaetter von Windenergieanlagen - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Siegmann, K.; Meola, G.; Hirayama, M.

    2009-08-15

    Iced rotor blades drastically reduce the energy production of wind turbines. In addition, ice throw from the iced blades can be dangerous. There are yet no convincing solutions for the icing problem. An interesting approach is the use of a rotor blade coating. We have developed a coating which influences the freezing behaviour of water. In this report, we describe tests on the antifreeze-coatings developed by us. It is shown that water droplets on the antifreeze coating freeze later than droplets on the untreated glass. This effect could lead to a non-icing of coated rotor blades, because the droplets could be blown of the blade before they can freeze. Additionally, the ice adhesion to the antifreeze coatings is measured. Ice adheres to the antifreeze coating about as good as to bare aluminium and better than to adhesion reducing coatings. (authors)

  2. 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

  3. Design Of Rotor Blade For Vertical Axis Wind Turbine Using Double Aerofoil

    DEFF Research Database (Denmark)

    Chougule, Prasad; Ratkovich, Nicolas Rios; Kirkegaard, Poul Henning

    Nowadays, small vertical axis wind turbines are receiving more attention compared to horizontal wind turbines due to their suitability in urban use because they generate less noise, have bird free turbines and lower cost. There is few vertical axis wind turbines design with good power curve....... However, the efficiency of power extraction has not been improved. Therefore, an attempt has been made to utilize high lift technology in practice for vertical axis wind turbines in order to improve power efficiency. High lift is obtained by double aerofoil elements mainly used in aeroplane wing design....... In this current work two aerofoils are used to design a rotor blade for a vertical axis wind turbine to improve the power efficiency on the rotor. Double aerofoil blade design consists of a main aerofoil and a slat aerofoil. The parameters related to position and orientation of the slat aerofoil with respect...

  4. Design Of Rotor Blade For Vertical Axis Wind Turbine Using Double Aerofoil

    DEFF Research Database (Denmark)

    Chougule, Prasad; Ratkovich, Nicolas Rios; Kirkegaard, Poul Henning;

    Nowadays, small vertical axis wind turbines are receiving more attention compared to horizontal wind turbines due to their suitability in urban use because they generate less noise, have bird free turbines and lower cost. There is few vertical axis wind turbines design with good power curve....... However, the efficiency of power extraction has not been improved. Therefore, an attempt has been made to utilize high lift technology in practice for vertical axis wind turbines in order to improve power efficiency. High lift is obtained by double aerofoil elements mainly used in aeroplane wing design....... In this current work two aerofoils are used to design a rotor blade for a vertical axis wind turbine to improve the power efficiency on the rotor. Double aerofoil blade design consists of a main aerofoil and a slat aerofoil. The parameters related to position and orientation of the slat aerofoil with respect...

  5. Performance of a Low Speed Axial Compressor Rotor Blade Row under Different Inlet Distortions

    Directory of Open Access Journals (Sweden)

    R. Taghavi Zenouz

    2017-05-01

    Full Text Available Responses of an axial compressor isolated rotor blade row to various inlet distortions have been investigated utilizing computational fluid dynamic technique. Distortions have been imposed by five screens of different geometries, but with the same blockage ratio. These screens were embedded upstream of the rotor blade row. Flow fields are simulated in detail for compressor design point and near stall conditions. Performance curves for distorted cases are extracted and compared to the undisturbed case. Flow simulations and consequent performance characteristics show that the worst cases belong to non-symmetric blockages, i.e., those of partial circumferential configurations. These cases produce the largest wakes which can disturb the flow, considerably. Superior performances correspond to the inner and outer continuous circumferential distortion screens. Since, they produce no significant disturbances to the main flow in comparison to the non-symmetric screens.

  6. Design, Test, and Evaluation of a Transonic Axial Compressor Rotor with Splitter Blades

    Science.gov (United States)

    2013-09-01

    Postgraduate School NPSMF NPS Military Fan NTG No Tip Gap PS Pressure Side SB Splitter Blade SS Suction Side SolidWorks A solid modeling...lubrication oil to the TASR and drive turbine bearings via an air driven oil mist system. A pre-test checklist is provided in McNab [8] Appendix C...modern high- performance compressor rotors. 79 LIST OF REFERENCES [1] A. J. Wennerstrom, Design of Highly Loaded Axial-Flow Fans and Compressors, White

  7. Stress analysis of advanced attack helicopter composite main rotor blade root end lug

    Science.gov (United States)

    Baker, D. J.

    1982-01-01

    Stress analysis of the Advanced Attack Helicopter (AAH) composite main rotor blade root end lug is described. The stress concentration factor determined from a finite element analysis is compared to an empirical value used in the lug design. The analysis and test data indicate that the stress concentration is primarily a function of configuration and independent of the range of material properties typical of Kevlar-49/epoxy and glass epoxy.

  8. Aeroelastic response and stability of tiltrotors with elastically-coupled composite rotor blades. Ph.D. Thesis

    Science.gov (United States)

    Nixon, Mark W.

    1993-01-01

    There is a potential for improving the performance and aeroelastic stability of tiltrotors through the use of elastically-coupled composite rotor blades. To study the characteristics of tiltrotors with these types of rotor blades it is necessary to formulate a new analysis which has the capabilities of modeling both a tiltrotor configuration and an anisotropic rotor blade. Background for these formulations is established in two preliminary investigations. In the first, the influence of several system design parameters on tiltrotor aeroelastic stability is examined for the high-speed axial flight mode using a newly-developed rigid-blade analysis with an elastic wing finite element model. The second preliminary investigation addresses the accuracy of using a one-dimensional beam analysis to predict frequencies of elastically-coupled highly-twisted rotor blades. Important aspects of the new aeroelastic formulations are the inclusion of a large steady pylon angle which controls tilt of the rotor system with respect to the airflow, the inclusion of elastic pitch-lag coupling terms related to rotor precone, the inclusion of hub-related degrees of freedom which enable modeling of a gimballed rotor system and engine drive-train dynamics, and additional elastic coupling terms which enable modeling of the anisotropic features for both the rotor blades and the tiltrotor wing. Accuracy of the new tiltrotor analysis is demonstrated by a comparison of the results produced for a baseline case with analytical and experimental results reported in the open literature. Two investigations of elastically tailored blades on a baseline tiltrotor are then conducted. One investigation shows that elastic bending-twist coupling of the rotor blade is a very effective means for increasing the flutter velocity of a tiltrotor, and the magnitude of coupling required does not have an adverse effect on performance or blade loads. The second investigation shows that passive blade twist control via

  9. A study on rotational augmentation using CFD analysis of flow in the inboard region of the MEXICO rotor blades

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Sørensen, Niels N.

    2015-01-01

    This work presents an analysis of data from existing as well as new full-rotor computational fluid dynamics computations on the MEXICO rotor, with focus on the flow around the inboard parts of the blades. The boundary layer separation characteristics on the airfoil sections in the inboard parts...

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

    Science.gov (United States)

    Wetzel, Kyle Kristopher

    2008-03-18

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

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

    Science.gov (United States)

    Wetzel, Kyle Kristopher

    2014-06-24

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

  12. Contribution to Experimental Validation of Linear and Non-Linear Dynamic Models for Representing Rotor-Blade Parametric Coupled Vibrations

    DEFF Research Database (Denmark)

    Santos, Ilmar; Saracho, C.M.; Smith, J.T.

    2004-01-01

    This work gives a theoretical and experimental contribution to the problem of rotor-blades dynamic interaction. A validation procedure of mathematical models is carried out with help of a simple test rig, built by a mass-spring system attached to four flexible rotating blades. With this test rig,...

  13. Condition monitoring of rotor blades of wind power systems; Zustandsueberwachung von Rotorblaettern an Windenergieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Frankenstein, B.; Froehlich, K.J.; Lieske, U.; Schuber, L. [Fraunhofer Institut Zerstoerungsfreie Pruefverfahren (IZFP), Institutsteil Dresden (Germany)

    2007-07-01

    The Fraunhofer Institute of Non-Destructive Testing Dresden (IzfP-D) uses condition monitoring systems, which by permanent monitoring e.g. of wind rotors, aircraft components, or pipelines are to ensure high availability of the object. This way, damage (e.g. crack initiation and propagation, delamination) can be detected early, and early repair measures will lengthen the life of the components and reduce standstill times during repair. Guided elastic waves are used for wind rotor monitoring, which are induced by piezo fibre converters. The contribution describes the method and measuring instrumentation for generation and detection of acoustic waves in composite materials. The focus is on static load tests of rotor blades, of which the status and trends are presented. (orig.)

  14. Comparative study of a three-bucket Savonius rotor with a combined three-bucket Savonius-three-bladed Darrieus rotor

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R.; Biswas, A.; Sharma, K.K. [Department of Mechanical Engineering, National Institute of Technology (NIT), Silchar 788 010, Assam (India)

    2008-09-15

    The vertical axis wind turbines are simple in construction, self-starting, inexpensive and can accept wind from any direction without orientation. A combined Savonius-Darrieus type vertical axis wind rotor has got many advantages over individual Savonius or individual Darrieus wind rotor, such as better efficiency than Savonius rotor and high starting torque than Darrieus rotor. But works on the combined Savonius-Darrieus wind rotor are very scare. In view of the above, two types of models, one simple Savonius and the other combined Savonius-Darrieus wind rotors were designed and fabricated. The Savonius rotor was a three-bucket system having provisions for overlap variations. The Savonius-Darrieus rotor was a combination of three-bucket Savonius and three-bladed Darrieus rotors with the Savonius placed on top of the Darrieus rotor. The overlap variation was made in the upper part, i.e. the Savonius rotor only. These were tested in a subsonic wind tunnel available in the department. The various parameters namely, power coefficients and torque coefficients were calculated for both overlap and without overlap conditions. From the present investigation, it is seen that with the increase of overlap, the power coefficients start decreasing. The maximum power coefficient of 51% is obtained at no overlap condition. However, while comparing the power coefficients (C{sub p}) for simple Savonius-rotor with that of the combined configuration of Savonius-Darrieus rotor, it is observed that there is a definite improvement in the power coefficient for the combined Savonius-Darrieus rotor without overlap condition. Combined rotor without overlap condition provided an efficiency of 0.51, which is higher than the efficiency of the Savonius rotor at any overlap positions under the same test conditions. (author)

  15. Design of automatic rotor blades folding system using NiTi shape memory alloy actuator

    Science.gov (United States)

    Ali, M. I. F.; Abdullah, E. J.

    2016-10-01

    This present paper will study the requirements for development of a new Automatic Rotor Blades Folding (ARBF) system that could possibly solve the availability, compatibility and complexity issue of upgrading a manual to a fully automatic rotor blades folding system of a helicopter. As a subject matter, the Royal Malaysian Navy Super Lynx Mk 100 was chosen as the baseline model. The aim of the study was to propose a design of SMART ARBF's Shape Memory Alloy (SMA) actuator and proof of operating concept using a developed scale down prototype model. The performance target for the full folding sequence is less than ten minutes. Further analysis on design requirements was carried out, which consisted of three main phases. Phase 1 was studying the SMA behavior on the Nickel Titanium (NiTi) SMA wire and spring (extension type). Technical values like activation requirement, contraction length, and stroke- power and stroke-temperature relationship were gathered. Phase 2 was the development of the prototype where the proposed design of stepped-retractable SMA actuator was introduced. A complete model of the SMART ARBF system that consisted of a base, a main rotor hub, four main rotor blades, four SMA actuators and also electrical wiring connections was fabricated and assembled. Phase 3 was test and analysis whereby a PINENG-PN968s-10000mAh Power Bank's 5 volts, which was reduced to 2.5 volts using LM2596 Step-Down Converter, powered and activated the NiTi spring inside each actuator. The bias spring (compression type), which functions to protract and push the blades to spread position, will compress together with the retraction of actuators and pull the blades to the folding position. Once the power was removed and SMA spring deactivated, the bias spring stiffness will extend the SMA spring and casing and push the blades back to spread position. The timing for the whole revolution was recorded. Based on the experimental analysis, the recorded timing for folding sequence is

  16. An evaluation of free- and fixed-vane flowmeters with curved- and flat-bladed Savonius rotors

    Science.gov (United States)

    Joseph, Antony; Desa, Ehrlich

    1994-04-01

    Speed and direction performances of flowmeters, designed by the authors for in-house use, employing an Aanderaa-type curved-bladed Savonius rotor and a free vane and an Aanderaa-type flat-bladed Savonius rotor and a fixed vane, are discussed. It has been observed that accuracy, linearity, and tilt response of a meter using the Aanderaa curved-bladed rotor is superior to those of a meter using the Aanderaa flat-bladed rotor. Analysis showed that the azimuth response of a flowmeter is affected by the presence of support rods surrounding its rotor. The change in azimuth response arises from flow pattern modifications in the vicinity of the rotor, imposed by the changes in the horizontal angle of the support rods of the rotor relative to the flow streamlines. While the use of two support rods may be suitable for a fixed-vane system, it is undesirable for a free-vane system where the meter's orientation with respect to the flow direction is not defined. Flow direction calibration results indicated that a fixed-vane system exhibits superior direction performance compared to a free-vane system. The comparatively poor direction performance of the free-vane system stems from the poor coupling to the 'vane-follower' magnet from the external vane.

  17. Helicopter rotor blade frequency evolution with damage growth and signal processing

    Science.gov (United States)

    Roy, Niranjan; Ganguli, Ranjan

    2005-05-01

    Structural damage in materials evolves over time due to growth of fatigue cracks in homogenous materials and a complicated process of matrix cracking, delamination, fiber breakage and fiber matrix debonding in composite materials. In this study, a finite element model of the helicopter rotor blade is used to analyze the effect of damage growth on the modal frequencies in a qualitative manner. Phenomenological models of material degradation for homogenous and composite materials are used. Results show that damage can be detected by monitoring changes in lower as well as higher mode flap (out-of-plane bending), lag (in-plane bending) and torsion rotating frequencies, especially for composite materials where the onset of the last stage of damage of fiber breakage is most critical. Curve fits are also proposed for mathematical modeling of the relationship between rotating frequencies and cycles. Finally, since operational data are noisy and also contaminated with outliers, denoising algorithms based on recursive median filters and radial basis function neural networks and wavelets are studied and compared with a moving average filter using simulated data for improved health-monitoring application. A novel recursive median filter is designed using integer programming through genetic algorithm and is found to have comparable performance to neural networks with much less complexity and is better than wavelet denoising for outlier removal. This filter is proposed as a tool for denoising time series of damage indicators.

  18. 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.

  19. Damage tolerance and structural monitoring for wind turbine blades

    Science.gov (United States)

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

    2015-01-01

    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. PMID:25583858

  20. 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...

  1. Preliminary structural design conceptualization for composite rotor for verdant power water current turbine

    Energy Technology Data Exchange (ETDEWEB)

    Paquette, J. A.

    2012-03-01

    Sandia National Laboratories (SNL) and Verdant Power Inc. (VPI) have partnered under a Cooperative Research and Development Agreement (CRADA) to develop a new kinetic hydropower rotor. The rotor features an improved hydrodynamic and structural design which features state-of-the-art technology developed for the wind industry. The new rotor will have higher energy capture, increased system reliability, and reduction of overall cost of energy. This project was divided into six tasks: (1) Composite Rotor Project Planning and Design Specification; (2) Baseline Fatigue Testing and Failure analysis; (3) Develop Blade/Rotor Performance Model; (4) Hydrofoil Survey and Selection; (5) FEM Structural Design; and (6) Develop Candidate Rotor Designs and Prepare Final Report.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    A. Shanyavskiy

    2016-10-01

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

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  6. A comprehensive investigation of trailing edge damage in a wind turbine rotor blade

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich; Eder, Martin Alexander; Belloni, Federico

    2016-01-01

    to damage. Empiricism tells that adhesive joints in blades often do not fulfil their expected lifetime, leading to considerable expenses because of repair or blade replacement. Owing to the complicated structural behaviour—in conjunction with the complex loading situation—literature about the root causes...

  7. Blade Deflection Measurements of a Full-Scale UH-60A Rotor System

    Science.gov (United States)

    Olson, Lawrence E.; Abrego, Anita; Barrows, Danny A.; Burner, Alpheus W.

    2010-01-01

    Blade deflection (BD) measurements using stereo photogrammetry have been made during the individual blade control (IBC) testing of a UH-60A 4-bladed rotor system in the 40 by 80-foot test section of the National Full-Scale Aerodynamic Complex (NFAC). Measurements were made in quadrants one and two, encompassing advance ratios from 0.15 to 0.40, thrust coefficient/solidities from 0.05 to 0.12 and rotor-system drive shaft angles from 0.0 to -9.6 deg. The experiment represents a significant step toward providing benchmark databases to be utilized by theoreticians in the development and validation of rotorcraft prediction techniques. In addition to describing the stereo measurement technique and reporting on preliminary measurements made to date, the intent of this paper is to encourage feedback from the rotorcraft community concerning continued analysis of acquired data and to solicit suggestions for improved test technique and areas of emphasis for measurements in the upcoming UH-60A Airloads test at the NFAC.

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  9. Effects of perforation number of blade on aerodynamic performance of dual-rotor small axial flow fans

    Science.gov (United States)

    Hu, Yongjun; Wang, Yanping; Li, Guoqi; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

    2015-04-01

    Compared with single rotor small axial flow fans, dual-rotor small axial flow fans is better regarding the static characteristics. But the aerodynamic noise of dual-rotor small axial flow fans is worse than that of single rotor small axial flow fans. In order to improve aerodynamic noise of dual-rotor small axial flow fans, the pre-stage blades with different perforation numbers are designed in this research. The RANS equations and the standard k-ɛ turbulence model as well as the FW-H noise model are used to simulate the flow field within the fan. Then, the aerodynamic performance of the fans with different perforation number is compared and analyzed. The results show that: (1) Compared to the prototype fan, the noise of fans with perforation blades is reduced. Additionally, the noise of the fans decreases with the increase of the number of perforations. (2) The vorticity value in the trailing edge of the pre-stage blades of perforated fans is reduced. It is found that the vorticity value in the trailing edge of the pre-stage blades decreases with the increase of the number of perforations. (3) Compared to the prototype fan, the total pressure rising and efficiency of the fans with perforation blades drop slightly.

  10. Improved Structure and Fabrication of Large, High-Power KHPS Rotors - Final Scientific/Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Corren, Dean [Verdant Power, Inc.; Colby, Jonathan [Verdant Power, Inc.; Adonizio, Mary Ann [Verdant Power, Inc.

    2013-01-29

    Verdant Power, Inc, working in partnership with the National Renewable Energy Laboratory (NREL), Sandia National Laboratories (SNL), and the University of Minnesota St. Anthony Falls Laboratory (SAFL), among other partners, used evolving Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) models and techniques to improve the structure and fabrication of large, high-power composite Kinetic Hydropower System (KHPS) rotor blades. The objectives of the project were to: design; analyze; develop for manufacture and fabricate; and thoroughly test, in the lab and at full scale in the water, the improved KHPS rotor blade.

  11. Comparison of far wakes behind a solid disk and a three-blade rotor

    DEFF Research Database (Denmark)

    Litvinov, I. V.; Naumov, I.V.; Okulov, Valery;

    2015-01-01

    A comparison of the wakes developed behind an immobile bluff body (solid disk) and a three-blade rotor at different rotational speeds is studied to find a correlation between them. LDA and PIV were applied to study the wakes behind both models in a water flume (Re ≈ 2.3·105). Everywhere in both...... deficit and rms of the velocity in both far wakes for the disk or the rotor shows a rational decay with the same power –2/3. It has good agreement with the analytical formula for the decay of the velocity deficit behind bluff bodies. A limit for using this model restricted by the turbulence level...

  12. Novel controller design demonstration for vibration alleviation of helicopter rotor blades

    Science.gov (United States)

    Ulker, Fatma Demet; Nitzsche, Fred

    2012-04-01

    This paper presents an advanced controller design methodology for vibration alleviation of helicopter rotor sys- tems. Particularly, vibration alleviation in a forward ight regime where the rotor blades experience periodically varying aerodynamic loading was investigated. Controller synthesis was carried out under the time-periodic H2 and H∞ framework and the synthesis problem was solved based on both periodic Riccati and Linear Matrix Inequality (LMI) formulations. The closed-loop stability was analyzed using Floquet-Lyapunov theory, and the controller's performance was validated by closed-loop high-delity aeroelastic simulations. To validate the con- troller's performance an actively controlled trailing edge ap strategy was implemented. Computational cost was compared for both formulations.

  13. Non-destructive testing of the ventilator blades from a generator rotor

    Energy Technology Data Exchange (ETDEWEB)

    Tuma, J.V. [Department for Revitalisation of Industrial Facilities and Equipment., Lubljana (Slovenia). Institute of Metals and Technology; Sipek, M. [Defektoskopija, Prevalje (Slovenia)

    2001-07-01

    An ultrasonic technique with surface waves and a magnetic particle technique with coil magnetization have been developed for testing the ventilator blades of a generator rotor. These techniques make it possible to detect transversal cracks, dot-shaped damage and impressions on the mounted and removed blades. (orig.) [German] Zur Kontrolle der Ventilatorschaufeln eines Generators auf Oberflaechenrisse wurde ein Ultraschallverfahren mit Oberflaechenwellen und ein Magnetpulververfahren mit Spulenmagnetisierung entwickelt. Die Ultraschallmethode ermoeglicht die Suche nach Querrissen an eingebauten oder demontierten Schaufeln. Mit der Magnetisierungsmethode werden auch Risse in der Wurzel der Schaufeln entdeckt. Praktische Pruefungen an den Schaufeln haben ergeben, dass die Ultraschallmethode mit Oberflaechenwellen am schnellsten und zuverlaessigsten, als zusaetzliche Methode an ausgebauten Schaufeln aber auch die Magnetpulverpruefung mit Spulenmagnetisierung geeignet ist. (orig.)

  14. Measurement of unsteady surface pressure on rotor blades of fans by pressure-sensitive paint

    Science.gov (United States)

    Yokoyama, Hiroshi; Miura, Kouhei; Iida, Akiyoshi

    2017-01-01

    To clarify the unsteady pressure distributions on the rotor blades of an axial fan, a pressure-sensitive paint (PSP) technique was used. To capture the image of the rotating fan as a static image, an optical derotator method with a dove prism was adopted. It was confirmed by preliminary experiments with a resonator and a speaker that the pressure fluctuations with 347 Hz can be measured by the present PSP. The measured mean pressure distributions were compared with the predicted results based on large-eddy simulations. The measured instantaneous surface pressure is instrumental to identify acoustic source of fan noise in the design stage.

  15. Vibrations of a Helicopter Rotor Blade Using Finite Element- Unconstrained Variational Formulations

    Science.gov (United States)

    1977-09-01

    agree well with the available data of Boyce , DiPrima and Handelman [11]. The torsional vibration frequency has only one eigen- value solution and, if CA...Equations of Motiqn for Combined Flapwise Bending, Chordwise Bending and Torsion of Twisted Rotor Blades,” NACA Report No. 1346, 1956. 11. W. E. Boyce ...R. C. DiPrima and G. H. - Handelman , “Vibrations of Rotating Beams of Constant Section,” Proceedings of the Second U.S. National Congress of Applied

  16. Efficiency enhancement in transonic compressor rotor blades using synthetic jets: A numerical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Benini, Ernesto; Biollo, Roberto; Ponza, Rita [Department of Mechanical Engineering - University of Padova, Via Venezia, 1 - 35131 Padova (Italy)

    2011-03-15

    Several passive and active techniques were studied and developed by compressor designers with the aim of improving the aerodynamic behavior of compressor blades by reducing, or even eliminating, flow separation. Fluidic-based methods, in particular, have been investigated for a long time, including both steady and unsteady suction, blowing and oscillating jets. Recently, synthetic jets (zero mass flux) have been proposed as a promising solution to reduce low-momentum fluid regions inside turbomachines. Synthetic jets, with the characteristics of zero net mass flux and non-zero momentum flux, do not require a complex system of pumps and pipes. They could be very efficient because at the suction part of the cycle the low-momentum fluid is sucked into the device, whereas in the blowing part a high-momentum jet accelerates it. To the authors' knowledge, the use of synthetic jets has never been experimented in transonic compressor rotors, where this technique could be helpful (i) to reduce the thickness and instability of blade suction side boundary layer after the interaction with the shock, and (ii) to delay the arising of the low-momentum region which can take place from the shock-tip clearance vortex interaction at low flow operating conditions, a flow feature which is considered harmful to rotor stability. Therefore, synthetic jets could be helpful to improve both efficiency and stall margin in transonic compressor rotors. In this paper, an accurate and validated CFD model is used to simulate the aerodynamic behavior of a transonic compressor rotor with and without synthetic jets. Four technical solutions were evaluated, different for jet position and velocity, and one was investigated in detail. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-06-08

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

  18. Radial Flow Effects On A Retreating Rotor Blade

    Science.gov (United States)

    2014-05-01

    estimate of the structural loading on horizontal axis wind turbines [52]. Studies have showed that such data consistently under predict actual loading...Oscillating Airfoil Experiments,” 1977. [18] Carta , F., “Dynamic Stall of Swept and Unswept Oscillating Wings,” tech. rep., DTIC Document, 1985. [19... Carta , F. O., A comparison of the pitching and plunging response of an oscillating airfoil, vol. 3172. National Aeronautics and Space Administration

  19. Acoustic performance of low pressure axial fan rotors with different blade chord length and radial load distribution

    Science.gov (United States)

    Carolus, Thomas

    The paper examines the acoustic and aerodynamic performance of low-pressure axial fan rotors with a hub/tip ratio of 0.45. Six rotors were designed for the same working point by means of the well-known airfoil theory. The condition of an equilibrium between the static pressure gradient and the centrifugal forces is maintained. All rotors have unequally spaced blades to diminish tonal noise. The rotors are tested in a short cylindrical housing without guide vanes. All rotors show very similar flux-pressure difference characteristics. The peak efficiency and the noise performance is considerably influenced by the chosen blade design. The aerodynamically and acoustically optimal rotor is the one with the reduced load at the hub and increased load in the tip region under satisfied equilibrium conditions. It runs at the highest aerodynamic efficiency, and its noise spectrum is fairly smooth. The overall sound pressure level of this rotor is up to 8 dB (A) lower compared to the other rotors under consideration.

  20. Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps

    Directory of Open Access Journals (Sweden)

    Uğbreve;ur Dalli

    2011-01-01

    Full Text Available An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.

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

    Science.gov (United States)

    Bielawa, R. L.

    1982-01-01

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

  2. Reliability analysis on resonance for low-pressure compressor rotor blade based on least squares support vector machine with leave-one-out cross-validation

    Directory of Open Access Journals (Sweden)

    Haifeng Gao

    2015-04-01

    Full Text Available This research article analyzes the resonant reliability at the rotating speed of 6150.0 r/min for low-pressure compressor rotor blade. The aim is to improve the computational efficiency of reliability analysis. This study applies least squares support vector machine to predict the natural frequencies of the low-pressure compressor rotor blade considered. To build a more stable and reliable least squares support vector machine model, leave-one-out cross-validation is introduced to search for the optimal parameters of least squares support vector machine. Least squares support vector machine with leave-one-out cross-validation is presented to analyze the resonant reliability. Additionally, the modal analysis at the rotating speed of 6150.0 r/min for the rotor blade is considered as a tandem system to simplify the analysis and design process, and the randomness of influence factors on frequencies, such as material properties, structural dimension, and operating condition, is taken into consideration. Back-propagation neural network is compared to verify the proposed approach based on the same training and testing sets as least squares support vector machine with leave-one-out cross-validation. Finally, the statistical results prove that the proposed approach is considered to be effective and feasible and can be applied to structural reliability analysis.

  3. Rotordynamic analysis of asymmetric turbofan rotor due to fan blade-loss event with contact-impact rub loads

    Science.gov (United States)

    Sinha, Sunil K.

    2013-04-01

    Loss of a blade from a running turbofan rotor introduces not only huge imbalance into the dynamical system rather it makes the entire rotor asymmetric as well. In a nonsymmetric rotor, the various terms of mass, gyroscopic and stiffness matrices also become time-dependent. In this paper, all the dynamical equations include the effect of the rotary inertia and gyroscopic moments as a result of both shaft bending as well as staggered blades flexing in-and-out of the plane of the disk. The governing equations also account for internal material damping in the shaft and the external damping in the support bearing system. In addition to the unbalance load at the disk location, the shaft may also be subjected to a torque and axial forces. Here, the fan blades are modeled as pre-twisted thin shallow shells. They have coupled flexural-torsional motion in the lateral out-of-plane direction as well as extensional degrees-of-freedom in the longitudinal spanwise direction of the blade airfoil. The effect of blade tip rub forces being transmitted to the shaft are analyzed in terms of the dynamic stability of the rotor, especially during windmilling.

  4. A New Single-blade Based Hybrid CFD Method for Hovering and Forward-flight Rotor Computation

    Institute of Scientific and Technical Information of China (English)

    SHI Yongjie; ZHAO Qijun; FAN Feng; XU Guohua

    2011-01-01

    A hybrid Euler/full potential/Lagrangian wake method, based on single-blade simulation, for predicting unsteady aerodynamic flow around helicopter rotors in hover and forward flight has been developed. In this method, an Euler solver is used to model the near wake evolution and transonic flow phenomena in the vicinity of the blade, and a full potential equation (FPE) is used to model the isentropic potential flow region far away from the rotor, while the wake effects of other blades and the far wake are incorporated into the flow solution as an induced inflow distribution using a Lagrangian based wake analysis. To further reduce the execution time, the computational fluid dynamics (CFD) solution and rotor wake analysis (including induced velocity update) are conducted parallelly, and a load balancing strategy is employed to account for the information exchange between two solvers. By the developed method, several hover and forward-flight cases on Caradonna-Tung and Helishape 7A rotors are performed. Good agreements of the loadings on blade surface with available measured data demonstrate the validation of the method. Also, the CPU time required for different computation runs is compared in the paper, and the results show that the present hybrid method is superior to conventional CFD method in time cost, and will be more efficient with the number of blades increasing.

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

    Science.gov (United States)

    2016-05-19

    1 Parametric Investigation of the Effect of Hub Pitching Moment on Blade Vortex Interaction (BVI) Noise of an Isolated Rotor Carlos Malpica...radiation. Objective The aim of this study is to investigate the sensitivity of BVI noise radiation to changes in the hub pitch moment trim state...calculations the aerodynamic loads on the blades were evaluated at azimuth intervals of 15 deg. The relatively large time (azimuth) step is

  6. Structural analysis considerations for wind turbine blades

    Science.gov (United States)

    Spera, D. A.

    1979-01-01

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

  7. Dynamic behavior of aero-engine rotor with fusing design suffering blade off

    Directory of Open Access Journals (Sweden)

    Cun WANG

    2017-06-01

    Full Text Available Fan blade off (FBO from a running turbofan rotor will introduce sudden unbalance into the dynamical system, which will lead to the rub-impact, the asymmetry of rotor and a series of interesting dynamic behavior. The paper first presents a theoretical study on the response excited by sudden unbalance. The results reveal that the reaction force of the bearing located near the fan could always reach a very high value which may lead to the crush of ball, journal sticking, high stress on the other components and some other failures to endanger the safety of engine in FBO event. Therefore, the dynamic influence of a safety design named “fusing” is investigated by mechanism analysis. Meantime, an explicit FBO model is established to simulate the FBO event, and evaluate the effectiveness and potential dynamic influence of fusing design. The results show that the fusing design could reduce the vibration amplitude of rotor, the reaction force on most bearings and loads on mounts, but the sudden change of support stiffness induced by fusing could produce an impact effect which will couple with the influence of sudden unbalance. Therefore, the implementation of the design should be considered carefully with optimized parameters in actual aero-engine.

  8. Overall and blade element performance of a 1.20-pressure-ratio fan stage with rotor blades reset -5 deg

    Science.gov (United States)

    Lewis, G. W., Jr.; Osborn, W. M.; Moore, R. D.

    1976-01-01

    A 51-cm-diam model of a fan stage for a short haul aircraft was tested in a single stage-compressor research facility. The rotor blades were set 5 deg toward the axial direction (opened) from design setting angle. Surveys of the air flow conditions ahead of the rotor, between the rotor and stator, and behind the stator were made over the stable operating range of the stage. At the design speed of 213.3 m/sec and a weight flow of 31.5 kg/sec, the stage pressure ratio and efficiency were 1.195 and 0.88, respectively. The design speed rotor peak efficiency of 0.91 occurred at the same flow rate.

  9. On the impact of multi-axial stress states on trailing edge bondlines in wind turbine rotor blades

    Science.gov (United States)

    Noever Castelos, Pablo; Balzani, Claudio

    2016-09-01

    For a reliable design of wind turbine systems all of their components have to be designed to withstand the loads appearing in the turbine's lifetime. When performed in an integral manner this is called systems engineering, and is exceptionally important for components that have an impact on the entire wind turbine system, such as the rotor blade. Bondlines are crucial subcomponents of rotor blades, but they are not much recognized in the wind energy research community. However, a bondline failure can lead to the loss of a rotor blade, and potentially of the entire turbine, and is extraordinarily relevant to be treated with strong emphasis when designing a wind turbine. Modern wind turbine rotor blades with lengths of 80 m and more offer a degree of flexibility that has never been seen in wind energy technology before. Large deflections result in high strains in the adhesive connections, especially at the trailing edge. The latest edition of the DNV GL guideline from end of 2015 demands a three-dimensional stress analysis of bondlines, whereas before an isolated shear stress proof was sufficient. In order to quantify the lack of safety from older certification guidelines this paper studies the influence of multi-axial stress states on the ultimate and fatigue load resistance of trailing edge adhesive bonds. For this purpose, detailed finite element simulations of the IWES IWT-7.5-164 reference wind turbine blades are performed. Different yield criteria are evaluated for the prediction of failure and lifetime. The results show that the multi-axial stress state is governed by span-wise normal stresses. Those are evidently not captured in isolated shear stress proofs, yielding non-conservative estimates of lifetime and ultimate load resistance. This finding highlights the importance to include a three-dimensional stress state in the failure analysis of adhesive bonds in modern wind turbine rotor blades, and the necessity to perform a three-dimensional characterization

  10. Development and Operation of an Automatic Rotor Trim Control System for the UH-60 Individual Blade Control Wind Tunnel Test

    Science.gov (United States)

    Theodore, Colin R.; Tischler, Mark B.

    2010-01-01

    An automatic rotor trim control system was developed and successfully used during a wind tunnel test of a full-scale UH-60 rotor system with Individual Blade Control (IBC) actuators. The trim control system allowed rotor trim to be set more quickly, precisely and repeatably than in previous wind tunnel tests. This control system also allowed the rotor trim state to be maintained during transients and drift in wind tunnel flow, and through changes in IBC actuation. The ability to maintain a consistent rotor trim state was key to quickly and accurately evaluating the effect of IBC on rotor performance, vibration, noise and loads. This paper presents details of the design and implementation of the trim control system including the rotor system hardware, trim control requirements, and trim control hardware and software implementation. Results are presented showing the effect of IBC on rotor trim and dynamic response, a validation of the rotor dynamic simulation used to calculate the initial control gains and tuning of the control system, and the overall performance of the trim control system during the wind tunnel test.

  11. Large-eddy simulation analysis of turbulent flow over a two-blade horizontal wind turbine rotor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Young [Dept. of Mechanical Engineering, Carnegie Mellon University, Pittsburgh (United States); You, Dong Hyun [Dept. of Mechanical Engineering, Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2016-11-15

    Unsteady turbulent flow characteristics over a two-blade horizontal wind turbine rotor is analyzed using a large-eddy simulation technique. The wind turbine rotor corresponds to the configuration of the U.S. National Renewable Energy Laboratory (NREL) phase VI campaign. The filtered incompressible Navier-Stokes equations in a non-inertial reference frame fixed at the centroid of the rotor, are solved with centrifugal and Coriolis forces using an unstructured-grid finite-volume method. A systematic analysis of effects of grid resolution, computational domain size, and time-step size on simulation results, is carried out. Simulation results such as the surface pressure coefficient, thrust coefficient, torque coefficient, and normal and tangential force coefficients are found to agree favorably with experimental data. The simulation showed that pressure fluctuations, which produce broadband flow-induced noise and vibration of the blades, are especially significant in the mid-chord area of the suction side at around 70 to 95 percent spanwise locations. Large-scale vortices are found to be generated at the blade tip and the location connecting the blade with an airfoil cross section and the circular hub rod. These vortices propagate downstream with helical motions and are found to persist far downstream from the rotor.

  12. Benchmarking aerodynamic prediction of unsteady rotor aerodynamics of active flaps on wind turbine blades using ranging fidelity tools

    Science.gov (United States)

    Barlas, Thanasis; Jost, Eva; Pirrung, Georg; Tsiantas, Theofanis; Riziotis, Vasilis; Navalkar, Sachin T.; Lutz, Thorsten; van Wingerden, Jan-Willem

    2016-09-01

    Simulations of a stiff rotor configuration of the DTU 10MW Reference Wind Turbine are performed in order to assess the impact of prescribed flap motion on the aerodynamic loads on a blade sectional and rotor integral level. Results of the engineering models used by DTU (HAWC2), TUDelft (Bladed) and NTUA (hGAST) are compared to the CFD predictions of USTUTT-IAG (FLOWer). Results show fairly good comparison in terms of axial loading, while alignment of tangential and drag-related forces across the numerical codes needs to be improved, together with unsteady corrections associated with rotor wake dynamics. The use of a new wake model in HAWC2 shows considerable accuracy improvements.

  13. Influence of the feed moisture, rotor speed, and blades gap on the performances of a biomass pulverization technology.

    Science.gov (United States)

    Luo, Siyi; Zhou, Yangmin; Yi, Chuijie; Luo, Yin; Fu, Jie

    2014-01-01

    Recently, a novel biomass pulverization technology was proposed by our group. In this paper, further detailed studies of this technology were carried out. The effects of feed moisture and crusher operational parameters (rotor speed and blades gap) on product particle size distribution and energy consumption were investigated. The results showed that higher rotor speed and smaller blades gap could improve the hit probability between blades and materials and enhance the impacting and grinding effects to generate finer products, however, resulting in the increase of energy consumption. Under dry conditions finer particles were much more easily achieved, and there was a tendency for the specific energy to increase with increasing feed moisture. Therefore, it is necessary for the raw biomass material to be dried before pulverization.

  14. Condition monitoring of rotor blades of modern wind power systems; Ueberwachung mit Hertz. Condition Monitoring von Rotorblaettern moderner Windenergieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Fecht, Nikolaus

    2010-06-15

    With seven wind turbines, the Austrian wind farm ''Sternwald'' is the biggest wind farm in Upper Austria. It is the only wind farm in a forest, and all turbines are therefore equipped with automatic fire fighting equipment. The mountain range on which the wind farm is located is about 1000 m high, with strong wind and much ice and snow in the winter season. For this reason, the owner decided to instal a condition monitoring system with ice detectors. The piezoelectric sensors are mounted directly on the rotor blades as measurements on the nacelle will always be incorrect. Installation on the rotor blades, on the other hand, makes high demands on the fastenings and sensors as the velocity of the blade tips may be up to 250 km per hour. (orig.)

  15. Rotor tip clearance effects on overall and blade-element performance of axial-flow transonic fan stage

    Science.gov (United States)

    Moore, R. D.

    1982-01-01

    The effects of tip clearance on the overall and blade-element performance of an axial-flow transonic fan stage are presented. The 50-centimeter-diameter fan was tested at four tip clearances (nonrotating) from 0.061 to 0.178 centimeter. The calculated radial growth of the blades was 0.040 centimeter at design conditions. The decrease in overall stage performance with increasing clearance is attributed to the loss in rotor performance. For the rotor the effects of clearance on performance parameters extended to about 70 percent of blade span from the tip. The stage still margin based on an assumed operating line decreased from 15.3 to 0 percent as the clearance increased from 0.061 to 0.178 centimeter.

  16. Fluid-structure coupling for wind turbine blade analysis using OpenFOAM

    Science.gov (United States)

    Dose, Bastian; Herraez, Ivan; Peinke, Joachim

    2015-11-01

    Modern wind turbine rotor blades are designed increasingly large and flexible. This structural flexibility represents a problem for the field of Computational Fluid Dynamics (CFD), which is used for accurate load calculations and detailed investigations of rotor aerodynamics. As the blade geometries within CFD simulations are considered stiff, the effect of blade deformation caused by aerodynamic loads cannot be captured by the common CFD approach. Coupling the flow solver with a structural solver can overcome this restriction and enables the investigation of flexible wind turbine blades. For this purpose, a new Finite Element (FE) solver was implemented into the open source CFD code OpenFOAM. Using a beam element formulation based on the Geometrically Exact Beam Theory (GEBT), the structural model can capture geometric non-linearities such as large deformations. Coupled with CFD solvers of the OpenFOAM package, the new framework represents a powerful tool for aerodynamic investigations. In this work, we investigated the aerodynamic performance of a state of the art wind turbine. For different wind speeds, aerodynamic key parameters are evaluated and compared for both, rigid and flexible blade geometries. The present work is funded within the framework of the joint project Smart Blades (0325601D) by the German Federal Ministry for Economic Affairs and Energy (BMWi) under decision of the German Federal Parliament.

  17. Aerodynamic parametric studies and sensitivity analysis for rotor blades in axial flight

    Science.gov (United States)

    Chiu, Y. D.; Peters, David A.

    1991-01-01

    The analytical capability is offered for aerodynamic parametric studies and sensitivity analyses of rotary wings in axial flight by using a 3D undistorted wake model in curved lifting line theory. The governing equations are solved by both the Multhopp Interpolation technique and the Vortex Lattice method. The singularity from the bound vortices is eliminated through the Hadamard's finite part concept. Good numerical agreement between both analytical methods and finite differences methods are found. Parametric studies were made to assess the effects of several shape variables on aerodynamic loads. It is found, e.g., that a rotor blade with out-of-plane and inplane curvature can theoretically increase lift in the inboard and outboard regions respectively without introducing an additional induced drag.

  18. Aerodynamic parameter studies and sensitivity analysis for rotor blades in axial flight

    Science.gov (United States)

    Chiu, Y. Danny; Peters, David A.

    1991-01-01

    The analytical capability is offered for aerodynamic parametric studies and sensitivity analyses of rotary wings in axial flight by using a 3-D undistorted wake model in curved lifting line theory. The governing equations are solved by both the Multhopp Interpolation technique and the Vortex Lattice method. The singularity from the bound vortices is eliminated through the Hadamard's finite part concept. Good numerical agreement between both analytical methods and finite differences methods are found. Parametric studies were made to assess the effects of several shape variables on aerodynamic loads. It is found, e.g., that a rotor blade with out-of-plane and inplane curvature can theoretically increase lift in the inboard and outboard regions respectively without introducing an additional induced drag.

  19. A piloted comparison of elastic and rigid blade-element rotor models using parallel processing technology

    Science.gov (United States)

    Hill, Gary; Du Val, Ronald W.; Green, John A.; Huynh, Loc C.

    1990-01-01

    A piloted comparison of rigid and aeroelastic blade-element rotor models was conducted at the Crew Station Research and Development Facility (CSRDF) at Ames Research Center. FLIGHTLAB, a new simulation development and analysis tool, was used to implement these models in real time using parallel processing technology. Pilot comments and quantitative analysis performed both on-line and off-line confirmed that elastic degrees of freedom significantly affect perceived handling qualities. Trim comparisons show improved correlation with flight test data when elastic modes are modeled. The results demonstrate the efficiency with which the mathematical modeling sophistication of existing simulation facilities can be upgraded using parallel processing, and the importance of these upgrades to simulation fidelity.

  20. An analysis of thermal stress and gas bending effects on vibrations of compressor rotor stages. [blade torsional rigidity

    Science.gov (United States)

    Chen, L.-T.; Dugundji, J.

    1979-01-01

    A preliminary study conducted by Kerrebrock et al. (1976) has shown that the torsional rigidity of untwisted thin blades of a transonic compressor can be reduced significantly by transient thermal stresses. The aerodynamic loads have various effects on blade vibration. One effect is that gas bending loads may result in a bending-torsion coupling which may change the characteristics of the torsion and bending vibration of the blade. For a general study of transient-temperature distribution within a rotor stage, a finite-element heat-conduction analysis was developed. The blade and shroud are divided into annular elements. With a temperature distribution obtained from the heat-conduction analysis and a prescribed gas bending load distribution along the blade span, the static deformation and moment distributions of the blade can be solved iteratively using the finite-element method. The reduction of the torsional rigidity of pretwisted blades caused by the thermal stress effect is then computed. The dynamic behavior of the blade is studied by a modified Galerkin's method.

  1. An analysis of thermal stress and gas bending effects on vibrations of compressor rotor stages. [blade torsional rigidity

    Science.gov (United States)

    Chen, L.-T.; Dugundji, J.

    1979-01-01

    A preliminary study conducted by Kerrebrock et al. (1976) has shown that the torsional rigidity of untwisted thin blades of a transonic compressor can be reduced significantly by transient thermal stresses. The aerodynamic loads have various effects on blade vibration. One effect is that gas bending loads may result in a bending-torsion coupling which may change the characteristics of the torsion and bending vibration of the blade. For a general study of transient-temperature distribution within a rotor stage, a finite-element heat-conduction analysis was developed. The blade and shroud are divided into annular elements. With a temperature distribution obtained from the heat-conduction analysis and a prescribed gas bending load distribution along the blade span, the static deformation and moment distributions of the blade can be solved iteratively using the finite-element method. The reduction of the torsional rigidity of pretwisted blades caused by the thermal stress effect is then computed. The dynamic behavior of the blade is studied by a modified Galerkin's method.

  2. Helicopter model rotor-blade vortex interaction impulsive noise: Scalability and parametric variations

    Science.gov (United States)

    Splettstoesser, W. R.; Schultz, K. J.; Boxwell, D. A.; Schmitz, F. H.

    1984-01-01

    Acoustic data taken in the anechoic Deutsch-Niederlaendischer Windkanal (DNW) have documented the blade vortex interaction (BVI) impulsive noise radiated from a 1/7-scale model main rotor of the AH-1 series helicopter. Averaged model scale data were compared with averaged full scale, inflight acoustic data under similar nondimensional test conditions. At low advance ratios (mu = 0.164 to 0.194), the data scale remarkable well in level and waveform shape, and also duplicate the directivity pattern of BVI impulsive noise. At moderate advance ratios (mu = 0.224 to 0.270), the scaling deteriorates, suggesting that the model scale rotor is not adequately simulating the full scale BVI noise; presently, no proved explanation of this discrepancy exists. Carefully performed parametric variations over a complete matrix of testing conditions have shown that all of the four governing nondimensional parameters - tip Mach number at hover, advance ratio, local inflow ratio, and thrust coefficient - are highly sensitive to BVI noise radiation.

  3. Numerical investigation on super-cooled large droplet icing of fan rotor blade in jet engine

    Science.gov (United States)

    Isobe, Keisuke; Suzuki, Masaya; Yamamoto, Makoto

    2014-10-01

    Icing (or ice accretion) is a phenomenon in which super-cooled water droplets impinge and accrete on a body. It is well known that ice accretion on blades and vanes leads to performance degradation and has caused severe accidents. Although various anti-icing and deicing systems have been developed, such accidents still occur. Therefore, it is important to clarify the phenomenon of ice accretion on an aircraft and in a jet engine. However, flight tests for ice accretion are very expensive, and in the wind tunnel it is difficult to reproduce all climate conditions where ice accretion can occur. Therefore, it is expected that computational fluid dynamics (CFD), which can estimate ice accretion in various climate conditions, will be a useful way to predict and understand the ice accretion phenomenon. On the other hand, although the icing caused by super-cooled large droplets (SLD) is very dangerous, the numerical method has not been established yet. This is why SLD icing is characterized by splash and bounce phenomena of droplets and they are very complex in nature. In the present study, we develop an ice accretion code considering the splash and bounce phenomena to predict SLD icing, and the code is applied to a fan rotor blade. The numerical results with and without the SLD icing model are compared. Through this study, the influence of the SLD icing model is numerically clarified.

  4. Analysis and Testing of a Composite Fuselage Shield for Open Rotor Engine Blade-Out Protection

    Science.gov (United States)

    Pereira, J. Michael; Emmerling, William; Seng, Silvia; Frankenberger, Charles; Ruggeri, Charles R.; Revilock, Duane M.; Carney, Kelly S.

    2016-01-01

    The Federal Aviation Administration is working with the European Aviation Safety Agency to determine the certification base for proposed new engines that would not have a containment structure on large commercial aircraft. Equivalent safety to the current fleet is desired by the regulators, which means that loss of a single fan blade will not cause hazard to the Aircraft. The NASA Glenn Research Center and The Naval Air Warfare Center (NAWC), China Lake, collaborated with the FAA Aircraft Catastrophic Failure Prevention Program to design and test lightweight composite shields for protection of the aircraft passengers and critical systems from a released blade that could impact the fuselage. LS-DYNA® was used to predict the thickness of the composite shield required to prevent blade penetration. In the test, two composite blades were pyrotechnically released from a running engine, each impacting a composite shield with a different thickness. The thinner shield was penetrated by the blade and the thicker shield prevented penetration. This was consistent with pre-test LS-DYNA predictions. This paper documents the analysis conducted to predict the required thickness of a composite shield, the live fire test from the full scale rig at NAWC China Lake and describes the damage to the shields as well as instrumentation results.

  5. Design and preliminary tests of a blade tip air mass injection system for vortex modification and possible noise reduction on a full-scale helicopter rotor

    Science.gov (United States)

    Pegg, R. J.; Hosier, R. N.; Balcerak, J. C.; Johnson, H. K.

    1975-01-01

    Full-scale tests were conducted on the Langley helicopter rotor test facility as part of a study to evaluate the effectiveness of a turbulent blade tip air mass injection system in alleviating the impulsive noise (blade slap) caused by blade-vortex interaction. Although blade-slap conditions could not be induced during these tests, qualitative results from flow visualization studies using smoke showed that the differential velocity between the jet velocity and the rotor tip speed was a primary parameter controlling the vortex modification.

  6. Effects of a trailing edge flap on the aerodynamics and acoustics of rotor blade-vortex interactions

    Science.gov (United States)

    Charles, B. D.; Tadghighi, H.; Hassan, A. A.

    1992-01-01

    The use of a trailing edge flap on a helicopter rotor has been numerically simulated to determine if such a device can mitigate the acoustics of blade vortex interactions (BVI). The numerical procedure employs CAMRAD/JA, a lifting-line helicopter rotor trim code, in conjunction with RFS2, an unsteady transonic full-potential flow solver, and WOPWOP, an acoustic model based on Farassat's formulation 1A. The codes were modified to simulate trailing edge flap effects. The CAMRAD/JA code was used to compute the far wake inflow effects and the vortex wake trajectories and strengths which are utilized by RFS2 to predict the blade surface pressure variations. These pressures were then analyzed using WOPWOP to determine the high frequency acoustic response at several fixed observer locations below the rotor disk. Comparisons were made with different flap deflection amplitudes and rates to assess flap effects on BVI. Numerical experiments were carried out using a one-seventh scale AH-1G rotor system for flight conditions simulating BVI encountered during low speed descending flight with and without flaps. Predicted blade surface pressures and acoustic sound pressure levels obtained have shown good agreement with the baseline no-flap test data obtained in the DNW wind tunnel. Numerical results indicate that the use of flaps is beneficial in reducing BVI noise.

  7. Structural health monitoring of wind turbine blades

    Science.gov (United States)

    Rumsey, Mark A.; Paquette, Joshua A.

    2008-03-01

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

  8. Enhancing the damping of wind turbine rotor blades, the DAMPBLADE project

    DEFF Research Database (Denmark)

    Chaviaropoulos, P.K.; Politis, E.S.; Lekou, D.J.

    2006-01-01

    A research programme enabling the development of damped wind turbine blades, having the acronym DAMPBLADE, has been supported by the EC under its 5th Framework Programme. In DAMPBLADE the following unique composite damping mechanisms were exploited aiming to increase the structural damping...

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    Mengal Ali Nawaz

    2014-07-01

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

  11. 14 CFR 29.547 - Main and tail rotor structure.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main and tail rotor structure. 29.547 Section 29.547 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Requirements § 29.547 Main and tail rotor structure. (a) A rotor is an assembly of rotating components, which...

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

    Science.gov (United States)

    Lim, Dong-Won

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

  13. Flow-driven rotor simulation of vertical axis tidal turbines: A comparison of helical and straight blades

    Directory of Open Access Journals (Sweden)

    Le Tuyen Quang

    2014-06-01

    Full Text Available In this study, flow-driven rotor simulations with a given load are conducted to analyze the operational characteristics of a vertical-axis Darrieus turbine, specifically its self-starting capability and fluctuations in its torque as well as the RPM. These characteristics are typically observed in experiments, though they cannot be acquired in simulations with a given tip speed ratio (TSR. First, it is shown that a flow-driven rotor simulation with a two-dimensional (2D turbine model obtains power coefficients with curves similar to those obtained in a simulation with a given TSR. 3D flowdriven rotor simulations with an optimal geometry then show that a helical-bladed turbine has the following prominent advantages over a straight-bladed turbine of the same size: an improvement of its self-starting capabilities and reduced fluctuations in its torque and RPM curves as well as an increase in its power coefficient from 33% to 42%. Therefore, it is clear that a flow-driven rotor simulation provides more information for the design of a Darrieus turbine than a simulation with a given TSR before experiments.

  14. 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)

  15. Anti-freeze coatings for the rotor blades of wind turbines; Anti-freeze Beschichtungen fuer Rotorblaetter von Windenergieanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Siegmann, K.; Kaufmann, A.; Hirayama, M.

    2006-07-01

    This final report for the Swiss Federal Office of Energy (SFOE) takes a look at projects involving the development of suggestions for coatings for the rotor blades of wind turbines. The coatings are to reduce the formation of hoarfrost on the leading edges of the blades. Various coatings are described and the mechanisms involved in the formation of the frost and in keeping the blades as free as possible from frost are discussed. Global know-how on the subject is discussed, as is know-how available in Europe and Switzerland. Manufacturers, planning offices and installation operators are listed, as are research institutes who are dealing with this problem. In the summary, the authors stress the importance of choosing the coating most suitable for the actual climatic conditions at the wind turbine's location. A suggestion is made for further work in this area.

  16. Turbine blade with tuned damping structure

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Christian X.; Messmann, Stephen J.

    2015-09-01

    A turbine blade is provided comprising: a root; an airfoil comprising an external wall extending radially from the root and having a radially outermost portion; and a damping structure. The external wall may comprise first and second side walls joined together to define an inner cavity of the airfoil. The damping structure may be positioned within the airfoil inner cavity and coupled to the airfoil so as to define a tuned mass damper.

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

    Science.gov (United States)

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

    2012-09-01

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

  18. Partitioned Fluid-Structure Interaction for Full Rotor Computations Using CFD

    DEFF Research Database (Denmark)

    Heinz, Joachim Christian

    ) based aerodynamic model which is computationally cheap but includes several limitations and corrections in order to account for three-dimensional and unsteady eects. The present work discusses the development of an aero-elastic simulation tool where high-fidelity computational fluid dynamics (CFD......In the design of modern wind turbines with long and slender rotor blades it becomes increasingly important to model and understand the evolving aero-elastic eects in more details. Standard stateof-the-art aero-elastic simulation tools for wind turbines usually employ a blade element momentum (BEM......) is used to model the aerodynamics of the flexible wind turbine rotor. Respective CFD computations are computationally expensive but do not show the limitations of the BEM-based models. It is one of the first times that high-fidelity fluid-structure interaction (FSI) simulations are used to model the aero...

  19. Methods for Expanding Rotary Wing Aircraft Health and Usage Monitoring Systems to the Rotating Frame through Real-time Rotor Blade Kinematics Estimation

    Science.gov (United States)

    Allred, Charles Jefferson

    Since the advent of Health and Usage Monitoring Systems (HUMS) in the early 1990's, there has been a steady decrease in the number of component failure related helicopter accidents. Additionally, measurable cost benefits due to improved maintenance practices based on HUMS data has led to a desire to expand HUMS from its traditional area of helicopter drive train monitoring. One of the areas of greatest interest for this expansion of HUMS is monitoring of the helicopter rotor head loads. Studies of rotor head load and blade motions have primarily focused on wind tunnel testing with technology which would not be applicable for production helicopter HUMS deployment, or measuring bending along the blade, rather than where it is attached to the rotor head and the location through which all the helicopter loads pass. This dissertation details research into finding methods for real time methods of estimating rotor blade motion which could be applied across helicopter fleets as an expansion of current HUMS technology. First, there is a brief exploration of supporting technologies which will be crucial in enabling the expansion of HUMS from the fuselage of helicopters to the rotor head: wireless data transmission and energy harvesting. A brief overview of the commercially available low power wireless technology selected for this research is presented. The development of a relatively high-powered energy harvester specific to the motion of helicopter rotor blades is presented and two different prototypes of the device are shown. Following the overview of supporting technologies, two novel methods of monitoring rotor blade motion in real time are developed. The first method employs linear displacement sensors embedded in the elastomer layers of a high-capacity laminate bearing of the type commonly used in fully articulated rotors throughout the helicopter industry. The configuration of these displacement sensors allows modeling of the sensing system as a robotic parallel

  20. Vibration reduction in helicopter rotors using an actively controlled partial span trailing edge flap located on the blade

    Science.gov (United States)

    Millott, T. A.; Friedmann, P. P.

    1994-01-01

    This report describes an analytical study of vibration reduction in a four-bladed helicopter rotor using an actively controlled, partial span, trailing edge flap located on the blade. The vibration reduction produced by the actively controlled flap (ACF) is compared with that obtained using individual blade control (IBC), in which the entire blade is oscillated in pitch. For both cases a deterministic feedback controller is implemented to reduce the 4/rev hub loads. For all cases considered, the ACF produced vibration reduction comparable with that obtained using IBC, but consumed only 10-30% of the power required to implement IBC. A careful parametric study is conducted to determine the influence of blade torsional stiffness, spanwise location of the control flap, and hinge moment correction on the vibration reduction characteristics of the ACF. The results clearly demonstrate the feasibility of this new approach to vibration reduction. It should be emphasized than the ACF, used together with a conventional swashplate, is completely decoupled from the primary flight control system and thus it has no influence on the airworthiness of the helicopter. This attribute is potentially a significant advantage when compared to IBC.

  1. Effects of Mie tip-vane on pressure distribution of rotor blade and power augmentation of horizontal axis wind turbine; Yokutan shoyoku Mie ben ni yoru suiheijiku fusha yokumenjo no atsuryoku bunpu no kaizen to seino kojo tono kankei

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Y.; Maeda, T.; Kamada, Y. [Mie Univ., Mie (Japan); Seto, H. [Mitsubishi Motors Corp., Tokyo (Japan)

    2000-04-01

    By recent developments of exclusive rotor blade, the efficiency of wind turbine is improved substantially. By measuring pressure on rotor blades of horizontal axis wind turbines rotating in wind tunnels, this report clarified relation between improvement of pressure distribution on main rotor blades by Mie vane and upgrade of wind turbine performance. The results under mentioned have been got by measuring pressure distribution on rotor blades, visualization by tuft, and measuring resistance of Mie vane. (1) The difference of pressure between suction surface and pressure surface on the end of rotor blade increase, and output power of wind turbine improves. (2) Vortex of blade end is inhibited by Mie vane. (3) The reason of reduction on wind turbine performance with Mie vane in aria of high rotating speed ratio is the increase of Mie vane flow resistance.(NEDO)

  2. 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.

  3. Software integration for automated stability analysis and design optimization of a bearingless rotor blade

    Science.gov (United States)

    Gunduz, Mustafa Emre

    to probe the design space of several local minima and maxima. After analysis of numerous samples, an optimum configuration of the design that is more stable than that of the initial design is reached. The above process requires several software tools: CATIA as the CAD tool, ANSYS as the FEA tool, VABS for obtaining the cross-sectional structural properties, and DYMORE for the frequency and dynamic analysis of the rotor. MATLAB codes are also employed to generate input files and read output files of DYMORE. All these tools are connected using ModelCenter.

  4. Acoustic emission analysis in overall fatigue testing of a wind rotor blade; Schallemissionsanalyse beim Gesamtermuedungstest eines Windkraftrotorblattes

    Energy Technology Data Exchange (ETDEWEB)

    Schulze, Eberhard; Frankenstein, Bernd; Schubert, Lars [Fraunhofer-Instiut fuer Zerstoerungsfreie Pruefverfahren (IZFP), Dresden (Germany)

    2009-07-01

    The Fraunhofer Institut fuer zerstoerungsfreie Pruefverfahren Dresden (IZFP-D, Fraunhofer Institute of Nondestructive Testing) is developing condition monitoring systems (CMS) for safety-relevant components. By permanent monitoring, e.g. of wind rotors, aircraft components or pipelines, these systems will ensure high avalability during the whole component life. Crack initiation, crack propagation or delamination can be detected and repaired at an early stage. Early repair will prolong the component life, and outage periods can be reduced. Currently, full-scale fatigue tests are made on a 40 m wind rotor blade of CFRP and GFRP materials. After a static pre-load period, 2,000,000 fatigue cycles will be applied. The contribution describes the measuring technology and the evaluation methods, in particular event identification and parametrization. Finally, the current experimental status is outlined, fatigue test results so far are presented, and development trends are indicated. (orig.)

  5. Influence of time domain unsteady aerodynamics on coupled flap-lag-torsional aeroelastic stability and response of rotor blades

    Science.gov (United States)

    Friedmann, P. P.; Robinson, L. H.

    1988-01-01

    This paper describes the incorporation of finite-state, time-domain aerodynamics in a flag-lag-torsional aeroelastic stability and response analysis in forward flight. Improvements to a previous formulation are introduced which eliminate spurious singularities. The methodology for solving the aeroelastic stability and response problems with augmented states, in the time domain, is presented using an implicit formulation. Results describing the aeroelastic behavior of soft and stiff in-plane hingeless rotor blades, in forward flight, are presented to illustrate the sensitivity of both the stability and response problems to time domain unsteady aerodynamics.

  6. Influence of time domain unsteady aerodynamics on coupled flap-lag-torsional aeroelastic stability and response of rotor blades

    Science.gov (United States)

    Friedmann, P. P.; Robinson, L. H.

    1988-01-01

    This paper describes the incorporation of finite-state, time-domain aerodynamics in a flag-lag-torsional aeroelastic stability and response analysis in forward flight. Improvements to a previous formulation are introduced which eliminate spurious singularities. The methodology for solving the aeroelastic stability and response problems with augmented states, in the time domain, is presented using an implicit formulation. Results describing the aeroelastic behavior of soft and stiff in-plane hingeless rotor blades, in forward flight, are presented to illustrate the sensitivity of both the stability and response problems to time domain unsteady aerodynamics.

  7. Redesigned rotor for a highly loaded, 1800 ft/sec tip speed compressor fan stage 1: Aerodynamic and mechanical design

    Science.gov (United States)

    Halle, J. E.; Ruschak, J. T.

    1975-01-01

    A highly loaded, high tip-speed fan rotor was designed with multiple-circular-arc airfoil sections as a replacement for a marginally successful rotor which had precompression airfoil sections. The substitution of airfoil sections was the only aerodynamic change. Structural design of the redesigned rotor blade was guided by successful experience with the original blade. Calculated stress levels and stability parameters for the redesigned rotor are within limits demonstrated in tests of the original rotor.

  8. Start-up circuit upgrading to reduce the erosion of the rotor blades of the last stages of steam turbines and prevent the mass strips of stellite plates

    Science.gov (United States)

    Bozhko, V. V.; Gorin, A. V.; Zaitsev, I. V.; Kovalev, I. A.; Nosovitskii, I. A.; Orlik, V. G.; Lomagin, S. N.; Chernov, V. P.

    2017-03-01

    At turbine starts with low steam flow rates in idle mode, the low-pressure rotor blades consume energy, causing the ventilation heating of the stages and creating higher depression in them than in the condenser. This leads to the return steam flows in the exhaust of the low-pressure cylinder (LPC), reducing the heat due to the moisture of starting steam damps and cooling injections. It is shown that, as a result of upgrading with the transition to fully milled shroud platforms of rotor blades, the depression in the stages decreases and their cooling efficiency is reduced due to the removal of an elastic turn of the rotor blades under the action of centrifugal forces and seal of them by periphery. Heating the rotor blades of the last stages exceeds the temperature threshold of soldering resistance of stellite plates (150°C), and their mass strips begin. The start-up circuit providing both the temperature retention of the last stages lower the soldering resistance threshold due to overwetting the steam damps up to saturation condition and the high degree of removal from the dump steam of excessive erosive-dangerous condensed moisture was proposed, applied, and tested at the operating power unit. The investment in the development and application of the new start-up circuit are compensated in the course of a year owing to guaranteed prevention of the strips of stellite plates that lengthens the service life of the rotor blades of the last stages as well as increase of the rotor blade efficiency due to the sharp decrease of erosive wear of the profiles and reduction of their surface roughness. This reduces the annual consumption of equivalent fuel by approximately 1000 t for every 100 MW of installed capacity.

  9. An experimental investigation of the effect of rotor tip shape on helicopter blade-slap noise. [in the langley v/stol wind tunnel

    Science.gov (United States)

    Hoad, D. R.

    1979-01-01

    The effect of tip-shape modification on blade-vortex interaction-induced helicopter blade-slap noise was investigated. The general rotor model system (GRMS) with a 3.148 m (10.33 ft) diameter, four-bladed fully articulated rotor was installed in the Langley V/STOL wind tunnel. The tunnel was operated in the open-throat configuration with treatment to improve the semi-anechoic characteristics of the test chamber. Based on previous investigation, four promising tips (ogee, sub-wing, 60 deg swept-tapered, and end-plate) were used along with a standard square tip as a baseline configuration. Aerodynamic and acoustical data concerning the relative applicability of the various tip configurations for blade-slap noise reduction are presented without analysis or discussion.

  10. Thermosyphon Method for Cooling the Rotor Blades of High-Temperature Steam Turbines

    Directory of Open Access Journals (Sweden)

    Bogomolov Alexander R.

    2016-01-01

    Full Text Available The design scheme of closed two-phase thermosyphon were suggested that can provide standard thermal operation of blades of high-temperature steam turbine. The method for thermosyphon calculation is developed. The example of thermal calculation was implemented, it showed that to cool the steam turbine blades at their heating by high-temperature steam, the heat can be removed in the rear part of the blades by air with the temperature of about 440°C.

  11. Thermosyphon Method for Cooling the Rotor Blades of High-Temperature Steam Turbines

    Science.gov (United States)

    Bogomolov, Alexander R.; Temnikova, Elena Yu.

    2016-02-01

    The design scheme of closed two-phase thermosyphon were suggested that can provide standard thermal operation of blades of high-temperature steam turbine. The method for thermosyphon calculation is developed. The example of thermal calculation was implemented, it showed that to cool the steam turbine blades at their heating by high-temperature steam, the heat can be removed in the rear part of the blades by air with the temperature of about 440°C.

  12. Thermosyphon Method for Cooling the Rotor Blades of High-Temperature Steam Turbines

    OpenAIRE

    Bogomolov Alexander R.; Temnikova Elena Yu.

    2016-01-01

    The design scheme of closed two-phase thermosyphon were suggested that can provide standard thermal operation of blades of high-temperature steam turbine. The method for thermosyphon calculation is developed. The example of thermal calculation was implemented, it showed that to cool the steam turbine blades at their heating by high-temperature steam, the heat can be removed in the rear part of the blades by air with the temperature of about 440°C.

  13. Structural Reliability of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov

    by developing new models and standards or carrying out tests The following aspects are covered in detail: ⋅ The probabilistic aspects of ultimate strength of composite laminates are addressed. Laminated plates are considered as a general structural reliability system where each layer in a laminate is a separate...... system component. Methods for solving the system reliability are discussed in an example problem. ⋅ Probabilistic models for fatigue life of laminates and sandwich core are developed and calibrated against measurement data. A modified, nonlinear S-N relationship is formulated where the static strength...... the reliability against several modes of failure in two different structures. This includes reliability against blade-tower collision, and the reliability against ultimate and fatigue failure of a sandwich panel. The results from the reliability analyses are then used for calibrating partial safety factors...

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

    Directory of Open Access Journals (Sweden)

    Krawczyk J.

    2016-06-01

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

  15. Thermographic inspection of wind turbine rotor blade segment utilizing natural conditions as excitation source, Part II: The effect of climatic conditions on thermographic inspections - A long term outdoor experiment

    Science.gov (United States)

    Worzewski, Tamara; Krankenhagen, Rainer; Doroshtnasir, Manoucher

    2016-05-01

    The present study continues the work described in part I of this paper in evaluating a long-term-experiment, where a rotor blade segment of a wind turbine is exposed to the elements and thereby monitored with passive thermography. First, it is investigated whether subsurface features in rotor blades - mainly made of GFRP - can generally be detected with thermography from greater distances under favorable conditions. The suitability of the sun for acting as a heat source in applying active thermography has been tested in the previous study. In this study, the climatic influence on thermographic measurement is evaluated. It is demonstrated that there are favorable and unfavorable circumstances for imaging thermal contrasts which reflect inner structures and other subsurface features like potential defects. It turns out that solar radiation serves as a very effective heat source, but not at all times of day. Other environmental influences such as diurnal temperature variations also create temperature contrasts that permit conclusions on subsurface features. Particular scenarios are reconstructed with FEM-simulations in order to gain deeper insight into the driving mechanisms that produce the observed thermal contrasts. These investigations may help planning useful outdoor operations for inspecting rotor blades with thermography.

  16. Applications of Fluorogens with Rotor Structures in Solar Cells.

    Science.gov (United States)

    Ong, Kok-Haw; Liu, Bin

    2017-05-29

    Solar cells are devices that convert light energy into electricity. To drive greater adoption of solar cell technologies, higher cell efficiencies and reductions in manufacturing cost are necessary. Fluorogens containing rotor structures may be helpful in addressing some of these challenges due to their unique twisted structures and photophysics. In this review, we discuss the applications of rotor-containing molecules as dyes for luminescent down-shifting layers and luminescent solar concentrators, where their aggregation-induced emission properties and large Stokes shifts are highly desirable. We also discuss the applications of molecules containing rotors in third-generation solar cell technologies, namely dye-sensitized solar cells and organic photovoltaics, where the twisted 3-dimensional rotor structures are used primarily for aggregation control. Finally, we discuss perspectives on the future role of molecules containing rotor structures in solar cell technologies.

  17. Applications of Fluorogens with Rotor Structures in Solar Cells

    Directory of Open Access Journals (Sweden)

    Kok-Haw Ong

    2017-05-01

    Full Text Available Solar cells are devices that convert light energy into electricity. To drive greater adoption of solar cell technologies, higher cell efficiencies and reductions in manufacturing cost are necessary. Fluorogens containing rotor structures may be helpful in addressing some of these challenges due to their unique twisted structures and photophysics. In this review, we discuss the applications of rotor-containing molecules as dyes for luminescent down-shifting layers and luminescent solar concentrators, where their aggregation-induced emission properties and large Stokes shifts are highly desirable. We also discuss the applications of molecules containing rotors in third-generation solar cell technologies, namely dye-sensitized solar cells and organic photovoltaics, where the twisted 3-dimensional rotor structures are used primarily for aggregation control. Finally, we discuss perspectives on the future role of molecules containing rotor structures in solar cell technologies.

  18. A study of aeroelastic and structural dynamic effects in multi-rotor systems with application to hybrid heavy lift vehicles

    Science.gov (United States)

    Friedmann, P. P.

    1984-01-01

    An aeroelastic model suitable for the study of aeroelastic and structural dynamic effects in multirotor vehicles simulating a hybrid heavy lift vehicle was developed and applied to the study of a number of diverse problems. The analytical model developed proved capable of modeling a number of aeroelastic problems, namely: (1) isolated blade aeroelastic stability in hover and forward flight, (2) coupled rotor/fuselage aeromechanical problem in air or ground resonance, (3) tandem rotor coupled rotor/fuselage problems, and (4) the aeromechanical stability of a multirotor vehicle model representing a hybrid heavy lift airship (HHLA). The model was used to simulate the ground resonance boundaries of a three bladed hingeless rotor model, including the effect of aerodynamic loads, and the theoretical predictions compared well with experimental results. Subsequently the model was used to study the aeromechanical stability of a vehicle representing a hybrid heavy lift airship, and potential instabilities which could occur for this type of vehicle were identified. The coupling between various blade, supporting structure and rigid body modes was identified.

  19. Analysis on structural characteristics of rotors in twin-rotor cylinder-embedded piston engine

    Institute of Scientific and Technical Information of China (English)

    陈虎; 潘存云; 徐海军; 邓豪; 韩晨

    2014-01-01

    Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied. The quantity and forms of its sealing surfaces are reduced and simplified, and what’s more, the advantages of twin-rotor piston engine are inherited, such as high power density and no valve mechanism. Given the motion law of two rotors, its kinematic model is established, and the general expression for some parameters related to engine performance, such as the trajectory, displacement, velocity and acceleration of the piston and centroid trajectory, angular displacement, velocity and acceleration of the rod are presented. By selecting different variation patterns of relative angle of two rotors, the relevant variables are compared. It can be concluded that by designing the relative angle function of two rotors, the volume variation of working chamber can be changed. However, a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions, the swing magnitude of rod is proportional to link ratioλ, and the position of rod swing center is controlled by eccentricitye. In order to reduce the lateral force, a smaller value ofλshould be selected in the case of the structure, and the value ofe should be near 0.95. There is no relationship between the piston stroke and the variation process of relative angle of two rotors, the former is only proportional to the amplitude of relative angle of two rotors.

  20. Multi-life-stage monitoring system based on fibre bragg grating sensors for more reliable wind turbine rotor blades: Experimental and numerical analysis of deformation and failure in composite materials

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira

    and structural health monitoring of wind turbine blades. The work presented sets the required framework to develop a monitoring system based on fibre Bragg gratings (FBG), which can be applied to the different life stages of a wind turbine blade. In this concept, the different measured physical parameters...... turbine as long as it is monitored. Thus, a novel crack/damage detection method using FBG sensors is presented, and software/tools are developed for signal simulation and post-processing. The first part of the thesis is an introduction to the multi-life-stage monitoring system based on FBG sensors...... and the damage tolerant design of fibre reinforced materials, where the different theory and numerical models used are presented. The second part of the thesis is a compilation of scientific journal papers, in which the use of FBG sensors to monitor the different life-stages of the wind turbine rotor blade...

  1. 14 CFR 27.547 - Main rotor structure.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main rotor structure. 27.547 Section 27.547 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Main Component Requirements § 27.547 Main rotor...

  2. A comparison with theory of peak to peak sound level for a model helicopter rotor generating blade slap at low tip speeds

    Science.gov (United States)

    Fontana, R. R.; Hubbard, J. E., Jr.

    1983-01-01

    Mini-tuft and smoke flow visualization techniques have been developed for the investigation of model helicopter rotor blade vortex interaction noise at low tip speeds. These techniques allow the parameters required for calculation of the blade vortex interaction noise using the Widnall/Wolf model to be determined. The measured acoustics are compared with the predicted acoustics for each test condition. Under the conditions tested it is determined that the dominating acoustic pulse results from the interaction of the blade with a vortex 1-1/4 revolutions old at an interaction angle of less than 8 deg. The Widnall/Wolf model predicts the peak sound pressure level within 3 dB for blade vortex separation distances greater than 1 semichord, but it generally over predicts the peak S.P.L. by over 10 dB for blade vortex separation distances of less than 1/4 semichord.

  3. Optimisation of non-axisymmetric end wall contours for the rotor of a low speed, 1 1/2 stage research turbine with unshrouded blades

    CSIR Research Space (South Africa)

    Bergh, J

    2012-06-01

    Full Text Available improvements could be obtained through the design of custom end walls for the turbine. This investigation therefore covers the design of custom non-axisymmetric end wall contours for the rotor row of an annular turbine rig with unshrouded blades (the same rig...

  4. Helicopter Rotor Load Prediction Using a Geometrically Exact Beam with Multicomponent Model

    DEFF Research Database (Denmark)

    Lee, Hyun-Ku; Viswamurthy, S.R.; Park, Sang Chul

    2010-01-01

    rotor-blade/control-system model was loosely coupled with various inflow and wake models in order to simulate both hover and forward-flight conditions. The resulting rotor blade response and pitch link loads are in good agreement with those predicted byCAMRADII. The present analysis features both model......In this paper, an accurate structural dynamic analysis was developed for a helicopter rotor system including rotor control components, which was coupled to various aerodynamic and wake models in order to predict an aeroelastic response and the loads acting on the rotor. Its blade analysis was based...... on an intrinsic formulation of moving beams implemented in the time domain. The rotor control system was modeled as a combination of rigid and elastic components. A multicomponent analysis was then developed by coupling the beam finite element model with the rotor control system model to obtain a complete rotor-blade/control...

  5. 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)

  6. 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.

  7. Optimizing tuning masses for helicopter rotor blade vibration reduction including computed airloads and comparison with test data

    Science.gov (United States)

    Pritchard, Jocelyn I.; Adelman, Howard M.; Walsh, Joanne L.; Wilbur, Matthew L.

    1992-01-01

    An optimization procedure is developed for locating tuning masses on a rotor blade so that vibratory loads are minimized and hub-shear harmonics are reduced without adding a large mass penalty. The airloads are computed by means of a helicopter analysis for the cases of three vs six tuning masses, with attention given to the prediction of changes in airloads. Frequencies, airloads, and hub loads are computed with the CAMRAD/JA helicopter analysis code and the Conmin general-purpose optimization program. The hub shear is found to be significantly reduced in both cases with the added mass, and the reduction of hub shear is demonstrated under three flight conditions. Comparisons with wind-tunnel data demonstrate that the correlation of mass location is good and the relationship between mass location and flight speed is predicted well by the model.

  8. Comparisons of elastic and rigid blade-element rotor models using parallel processing technology for piloted simulations

    Science.gov (United States)

    Hill, Gary; Duval, Ronald W.; Green, John A.; Huynh, Loc C.

    1991-01-01

    A piloted comparison of rigid and aeroelastic blade-element rotor models was conducted at the Crew Station Research and Development Facility (CSRDF) at Ames Research Center. A simulation development and analysis tool, FLIGHTLAB, was used to implement these models in real time using parallel processing technology. Pilot comments and quantitative analysis performed both on-line and off-line confirmed that elastic degrees of freedom significantly affect perceived handling qualities. Trim comparisons show improved correlation with flight test data when elastic modes are modeled. The results demonstrate the efficiency with which the mathematical modeling sophistication of existing simulation facilities can be upgraded using parallel processing, and the importance of these upgrades to simulation fidelity.

  9. Comparison of elastic and rigid blade-element rotor models using parallel processing technology for piloted simulations

    Science.gov (United States)

    Hill, Gary; Du Val, Ronald W.; Green, John A.; Huynh, Loc C.

    1991-01-01

    A piloted comparison of rigid and aeroelastic blade-element rotor models was conducted at the Crew Station Research and Development Facility (CSRDF) at Ames Research Center. A simulation development and analysis tool, FLIGHTLAB, was used to implement these models in real time using parallel processing technology. Pilot comments and qualitative analysis performed both on-line and off-line confirmed that elastic degrees of freedom significantly affect perceived handling qualities. Trim comparisons show improved correlation with flight test data when elastic modes are modeled. The results demonstrate the efficiency with which the mathematical modeling sophistication of existing simulation facilities can be upgraded using parallel processing, and the importance of these upgrades to simulation fidelity.

  10. A methodology to guide the selection of composite materials in a wind turbine rotor blade design process

    Science.gov (United States)

    Bortolotti, P.; Adolphs, G.; Bottasso, C. L.

    2016-09-01

    This work is concerned with the development of an optimization methodology for the composite materials used in wind turbine blades. Goal of the approach is to guide designers in the selection of the different materials of the blade, while providing indications to composite manufacturers on optimal trade-offs between mechanical properties and material costs. The method works by using a parametric material model, and including its free parameters amongst the design variables of a multi-disciplinary wind turbine optimization procedure. The proposed method is tested on the structural redesign of a conceptual 10 MW wind turbine blade, its spar caps and shell skin laminates being subjected to optimization. The procedure identifies a blade optimum for a new spar cap laminate characterized by a higher longitudinal Young's modulus and higher cost than the initial one, which however in turn induce both cost and mass savings in the blade. In terms of shell skin, the adoption of a laminate with intermediate properties between a bi-axial one and a tri-axial one also leads to slight structural improvements.

  11. 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...

  12. ANALISA KEGAGALAN BLADE BARIS TERAKHIR PADA ROTOR TURBINE UAP TIPE CONDENSING

    Directory of Open Access Journals (Sweden)

    Adhi Komara

    2014-02-01

    Full Text Available Blades dari turbin uap merupakan komponen penting dalam pembangkit listrik. Analisa kegagalan blade turbin bertujuan untuk meningkatkan kehandalan sistem turbin secara umum. Kegagalan blade baris terakhir tekanan rendah yang terjadi pada turbine uap type condensing diawali dengan naiknya vibrasi secara mendadak pada area belakang dari 5μm menjadi 51μm. Analisa dan pengujian yang dilakukan adalah analisa steam purity, pengujian mechanical stress dan pengujian metallurgy (analisa material, fractography dan microstructure. Dari hasil analisa steam purity didapat bahwa kandungan silica/ SiO2 yang diambil dari beberapa titik pengambilan sample ditemukan melebihi dari batas maximum yang diperbolehkan sesuai dengan standard VGB (Vereinigung der Großkesselbesitzer/ Asosiasi pengguna boiler ukuran besar di German; yaitu < 0.02 mg/l. Penuaan material ditemukan dari hasil pengujian yang dilakukan melalui analisa metallurgy microstructure.

  13. Aeroelastic stability of periodic systems with application to rotor blade flutter

    Science.gov (United States)

    Friedmann, P.; Silverthorn, L. J.

    1974-01-01

    The dynamics of a helicopter blade in forward flight are described by a system of linear differential equations with periodic coefficients. The stability of this periodic aeroelastic system is determined, using multivariable Floquet-Liapunov theory. The transition matrix at the end of the period is evaluated by: (1) direct numerical integration, and (2) a new, approximate method, which consists in approximating a periodic function by a series of step functions. The numerical accuracy and efficiency of the methods is compared, and the second method is shown to be superior by far. Results illustrating the effect of the periodic coefficients and various blade parameters are presented.

  14. Design of Wind Turbine Blades

    DEFF Research Database (Denmark)

    2016-01-01

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

  15. Monitoring of a Wind Turbine Rotor using a Multi-blade Coordinate Framework

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Niemann, Hans Henrik; Poulsen, Niels Kjølstad

    2012-01-01

    In this paper a method to detect asymmetric faults in a wind turbine rotor is presented. The paper describes how fault diagnosis using an observer-based residual generator approach is able to distinguish between the nominal and faulty case by the injection of e.g. a sinusoidal excitation signal i...

  16. Shape Optimization of Wind Turbine Blades

    DEFF Research Database (Denmark)

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

    2009-01-01

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

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

    Science.gov (United States)

    Moroz,; Mieczyslaw, Emilian [San Diego, CA

    2008-06-03

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

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

    Directory of Open Access Journals (Sweden)

    A. Shanyavskiy

    2016-07-01

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

  19. On Structural Health Monitoring of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Skov, Jonas falk; Ulriksen, Martin Dalgaard; Dickow, Kristoffer Ahrens

    2013-01-01

    The aim of the present paper is to provide a state-of-the-art outline of structural health monitoring (SHM) techniques, utilizing temperature, noise and vibration, for wind turbine blades, and subsequently perform a typology on the basis of the typical four damage identification levels in SHM....... Before presenting the state-of-the-art outline, descriptions of structural damages typically occurring in wind turbine blades are provided along with a brief description of the four damage identification levels....

  20. Development and Operation of an Automatic Rotor Trim Control System for use During the UH-60 Individual Blade Control Wind Tunnel Test

    Science.gov (United States)

    Theodore, Colin R.

    2010-01-01

    A full-scale wind tunnel test to evaluate the effects of Individual Blade Control (IBC) on the performance, vibration, noise and loads of a UH-60A rotor was recently completed in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel [1]. A key component of this wind tunnel test was an automatic rotor trim control system that allowed the rotor trim state to be set more precisely, quickly and repeatably than was possible with the rotor operator setting the trim condition manually. The trim control system was also able to maintain the desired trim condition through changes in IBC actuation both in open- and closed-loop IBC modes, and through long-period transients in wind tunnel flow. This ability of the trim control system to automatically set and maintain a steady rotor trim enabled the effects of different IBC inputs to be compared at common trim conditions and to perform these tests quickly without requiring the rotor operator to re-trim the rotor. The trim control system described in this paper was developed specifically for use during the IBC wind tunnel test

  1. 旋翼复合材料桨叶弹损穿孔的有限元建模方法%FINITE ELEMENT MODLEING METHOD OF COMPOSITE ROTOR BLADE WITH BALLISTIC PERFORATION

    Institute of Scientific and Technical Information of China (English)

    孙中涛; 王华明

    2013-01-01

    军用直升机旋翼桨叶具有抗弹击设计要求.根据复合材料桨叶的结构特点和工作特性,提出了建立复合材料桨叶弹击穿孔有限元模型的等截面节点移除法,该建模方法先采用等截面拉伸建立桨叶典型结构段的三维模型,然后将弹孔处的节点移除以模拟桨叶的弹损状况.所建立的桨叶弹损模型具有较高的置信度和可接受的解算规模,可作为进一步研究复合材料桨叶抗弹击性能的基础.%The military helicopter rotor blade has design requirement of sustaining some kind of ballistic damage. According to the structural properties and operating characteristics of composite blades, this article provides an even cross-section and node removed method to build finite elements model of composite blade with ballistic perforation. This modeling method builds three-dimensional model of blade typical section by even cross-section tension, then nodes around bullet holes are removed to simulate ballistic damage of the blade. The model of ballistic blade built in this article has a high degree of confidence and an acceptable solver scale, it can be used for further research of composite blades performance of resisting ballistic damage.

  2. Application of Electric Capacity Measurements to Detecting Delamination in Blades of Helicopter’s Lifting and Auxiliary Rotors

    Directory of Open Access Journals (Sweden)

    Gębura Andrzej

    2017-06-01

    Full Text Available This paper represents a series of the authors’ publications concerning effects of atmospheric conditions on aircraft [5-6, 11]. Hazards connected with separation ( delamination of heating elements from blade’s spar , namely: increased susceptibility to ice formation as a result of change in aerodynamic profile, decreased deicing effectiveness, shortened life of heating elements , weakened strength of blade’s structure, are described. In order to monitor the above mentioned delamination process during its early phase, these authors proposed to measure systematically electric capacity between the heating element and blade’s spar by means of a technical method. The electric capacity measurements performed by these authors on blades both in laboratory and service conditions demonstrated their practical usefulness for assessing delamination extent as well as for identifying areas where heating element separation from spar occurred. The method in question is simple , cheap , fast and non-interferring (non-destructive as well as it does not require dismounting the blades off the helicopter. As proved in practice , it is especially useful in sea-rescue or military operational conditions. Special attention was paid to application of the method to composite blades where coming-off the heating element tape causes local overheating the blade structure , that impairs flexibility of composite’s layers and may lead even to local cracks which may trigger helicopter crash. These authors desire to apply the method as a standard unit of on-board diagnostic system in the future.

  3. 3D Navier-Stokes Simulations of a rotor designed for Maximum Aerodynamic Efficiency

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Madsen, Helge. Aa.; Gaunaa, Mac

    2007-01-01

    The present paper describes the design of a three-bladed wind turbine rotor taking into account maximum aerodynamic efficiency only and not considering structural as well as offdesign issues. The rotor was designed assuming constant induction for most of the blade span, but near the tip region a ...

  4. Aerodynamic studies on auxiliary blades in rotors of specifically slow radial blowers; Aerodynamische Untersuchungen von Zwischenschaufeln in Laufraedern spezifisch langsamlaeufiger Radialventilatoren

    Energy Technology Data Exchange (ETDEWEB)

    Basile, R.

    2002-07-01

    The influence of auxiliary blades in rotors of specifically slow radial blowers on the aerodynamic characteristics was investigated both numerically and experimentally for ten different rotor variants with different primary dimensions and with auxiliary blades. [German] In dieser Arbeit wird der Einfluss von Zwischenschaufeln in Laufraedern spezifisch langsamlaeufiger Radialventilatoren auf die aerodynamischen Kennwerte numerisch und experimentell untersucht. Hierzu werden zehn Laufradgrundvarianten ausgewaehlt, die sich in ihren Hauptabmessungen unterscheiden. In diese Grundvarianten werden Zwischenschaufeln eingesetzt. Die optimale Zwischenschaufelposition ist bei allen untersuchten Laufradvarianten immer mittig im Schaufelkanal. Die optimale Zwischenschaufellaenge ist von allen Geometrieparametern des Laufrades abhaengig. Als dominierender Parameter stellt sich jedoch die Hauptschaufelzahl heraus. Ausgehend von detaillierten Stromfelduntersuchungen wird zusaetzlich der Einfluss des Spaltmassenstroms auf die Stroemungsumlengung im Saugmundbereich untersucht. Auf der Basis der Minderleistungstheorie nach Pfleiderer werden die Minderleistungsfaktoren mit Hilfe numerischer Stromfelddaten fuer Laufraeder ohne und mit Zwischenschaufeln bestimmt. (orig.)

  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. Computational fluid dynamics analysis of a twisted airfoil shaped two-bladed H-Darrieus rotor made from fibreglass reinforced plastic (FRP

    Directory of Open Access Journals (Sweden)

    Rajat Gupta, Sukanta Roy, Agnimitra Biswas

    2010-11-01

    Full Text Available H-Darrieus rotor is a lift type device having two to three blades designed as airfoils. The blades are attached vertically to the central shaft through support arms. The support to vertical axis helps the rotor maintain its shape. In this paper, Computational Fluid Dynamics (CFD analysis of an airfoil shaped two-bladed H-Darrieus rotor using Fluent 6.2 software was performed. Based on the CFD results, a comparative study between experimental and computational works was carried out. The H-Darrieus rotor was 20cm in height, 5cm in chord and twisted with an angle of 30° at the trailing end. The blade material of rotor was Fiberglass Reinforced Plastic (FRP. The experiments were earlier conducted in a subsonic wind tunnel for various height-to-diameter (H/D ratios. A two dimensional computational modeling was done with the help of Gambit tool using unstructured grid. Realistic boundary conditions were provided for the model to have synchronization with the experimental conditions. Two dimensional steady-state segregated solver with absolute velocity formulation and cell based grid was considered, and a standard k-epsilon viscous model with standard wall functions was chosen. A first order upwind discretization scheme was adopted for pressure velocity coupling of the flow. The inlet velocities and rotor rotational speeds were taken from the experimental results. From the computational analysis, power coefficient (Cp and torque coefficient (Ct values at ten different H/D ratios namely 0.85, 1.0, 1.10, 1.33, 1.54, 1.72, 1.80, 1.92, 2.10 and 2.20 were calculated in order to predict the performances of the twisted H-rotor. The variations of Cp and Ct with tip speed ratios were analyzed and compared with the experimental results. The standard deviations of computational Cp and Ct from experimental Cp and Ct were obtained. From the computational analysis, the highest values of Cp and Ct were obtained at H/D ratios of 1.0 and 1.54 respectively. The

  7. On the design and structural analysis of jet engine fan blade structures

    Science.gov (United States)

    Amoo, Leye M.

    2013-07-01

    Progress in the design and structural analysis of commercial jet engine fan blades is reviewed and presented. This article is motivated by the key role fan blades play in the performance of advanced gas turbine jet engines. The fundamentals of the associated physics are emphasized. Recent developments and advancements have led to an increase and improvement in fan blade structural durability, stability and reliability. This article is intended as a high level review of the fan blade environment and current state of structural design to aid further research in developing new and innovative fan blade technologies.

  8. A practical approach to fracture analysis at the trailing edge of wind turbine rotor blades

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Bitsche, Robert; Nielsen, Magda

    2014-01-01

    of the trailing edge joint is a common failure type, and information on specific reasons is scarce. This paper is concerned with the estimation of the strain energy release rates (SERRs) in trailing edges of wind turbine blades in order to gain insight into the driving failure mechanisms. A method based...... on the virtual crack closure technique (VCCT) is proposed, which can be used to identify critical areas in the adhesive joint of a trailing edge. The paper gives an overview of methods applicable for fracture cases comprising non-parallel crack faces in the realm of linear fracture mechanics. Furthermore...

  9. Semi-structured meshes for axial turbomachinery blades

    Science.gov (United States)

    Sbardella, L.; Sayma, A. I.; Imregun, M.

    2000-03-01

    This paper describes the development and application of a novel mesh generator for the flow analysis of turbomachinery blades. The proposed method uses a combination of structured and unstructured meshes, the former in the radial direction and the latter in the axial and tangential directions, in order to exploit the fact that blade-like structures are not strongly three-dimensional since the radial variation is usually small. The proposed semi-structured mesh formulation was found to have a number of advantages over its structured counterparts. There is a significant improvement in the smoothness of the grid spacing and also in capturing particular aspects of the blade passage geometry. It was also found that the leading- and trailing-edge regions could be discretized without generating superfluous points in the far field, and that further refinements of the mesh to capture wake and shock effects were relatively easy to implement. The capability of the method is demonstrated in the case of a transonic fan blade for which the steady state flow is predicted using both structured and semi-structured meshes. A totally unstructured mesh is also generated for the same geometry to illustrate the disadvantages of using such an approach for turbomachinery blades. Copyright

  10. Investigation of UH-60A Rotor Structural Loads from Flight and Wind Tunnel Tests

    Science.gov (United States)

    2016-05-19

    focuses on the advance ratio of 0.3 cases (C8424 and R47P21) and presents the detailed analyses and comparisons with the test data. 3 DESCRIPTION OF...from the test , including non-dimensional rotor thrust, and hub rolling and pitching moments. In addition, rotor blade tip Mach num- ber, advance ...high-frequency oscillations in the test data in the first quadrant resulting from the wake interaction are also cap- tured in the coupled solution

  11. The impact of geometric non-linearities on the fatigue analysis of trailing edge bond lines in wind turbine rotor blades

    Science.gov (United States)

    Noever Castelos, Pablo; Balzani, Claudio

    2016-09-01

    The accurate prediction of stress histories for the fatigue analysis is of utmost importance for the design process of wind turbine rotor blades. As detailed, transient, and geometrically non-linear three-dimensional finite element analyses are computationally weigh too expensive, it is commonly regarded sufficient to calculate the stresses with a geometrically linear analysis and superimpose different stress states in order to obtain the complete stress histories. In order to quantify the error from geometrically linear simulations for the calculation of stress histories and to verify the practical applicability of the superposition principal in fatigue analyses, this paper studies the influence of geometric non-linearity in the example of a trailing edge bond line, as this subcomponent suffers from high strains in span-wise direction. The blade under consideration is that of the IWES IWT-7.5-164 reference wind turbine. From turbine simulations the highest edgewise loading scenario from the fatigue load cases is used as the reference. A 3D finite element model of the blade is created and the bond line fatigue assessment is performed according to the GL certification guidelines in its 2010 edition, and in comparison to the latest DNV GL standard from end of 2015. The results show a significant difference between the geometrically linear and non-linear stress analyses when the bending moments are approximated via a corresponding external loading, especially in case of the 2010 GL certification guidelines. This finding emphasizes the demand to reconsider the application of the superposition principal in fatigue analyses of modern flexible rotor blades, where geometrical nonlinearities become significant. In addition, a new load application methodology is introduced that reduces the geometrically non-linear behaviour of the blade in the finite element analysis.

  12. Calibration of partial safety factors for wind turbine rotor blades against fatigue; Kalibrering af partielle sikkerhedsfaktorer for udmattelse af vindmoellerotorer. Bilagsrapport

    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. (au)

  13. An Overview of Rotor Blades Optimum Design for Helicopter Vibration Reduction%直升机减振的旋翼桨叶优化设计研究综述

    Institute of Scientific and Technical Information of China (English)

    向锦武; 郭俊贤; 张晓谷

    2001-01-01

    Helicopter vibration level has been a problem for many helicopter configurations. Due to the great practical importance of the problem a considerable amount of research has been aimed at various aspects of vibration reduction and control. This paper presents the results of a survey of rotor blades optimum design of reducing vibration by modifying blade properties so as to reduce vibratory hub shears and moments, and thereby reduce the vibration level experienced in the fuselage. Important categories relative to this optimum design problems are considered: the integration of various disciplines and the optimum design objectives; structural and aerodynamic analysis model of the rotor blades for optimum design; numerical optimization and sensitivity analysis technology; and the further development on this subject. This paper is intended to put this design method in a proper perspective from the viewpoint of high performance helicopter design.%围绕降低直升机振动水平的旋翼桨叶减振优化设计,对国内外这方面研究进展情况作了综述;着重讨论了降低旋翼激振力减振优化设计分析中的几个主要问题,包括桨叶减振优化设计途径与目标,桨叶优化设计中的分析模型,优化设计方法及灵敏度分析技术,以及桨叶优化减振设计研究的最新发展方向和需进一步研究的问题等.

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

    DEFF Research Database (Denmark)

    Pavese, Christian; Tibaldi, Carlo; Zahle, Frederik

    2017-01-01

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

  15. A methodology for exploiting the tolerance for imprecision in genetic fuzzy systems and its application to characterization of rotor blade leading edge materials

    Science.gov (United States)

    Sánchez, Luciano; Couso, Inés; Palacios, Ana M.; Palacios, José L.

    2013-05-01

    A methodology for obtaining fuzzy rule-based models from uncertain data is proposed. The granularity of the linguistic discretization is decided with the help of a new estimation of the mutual information between ill-known random variables, and a combination of boosting and genetic algorithms is used for discovering new rules. This methodology has been applied to predict whether the coating of an helicopter rotor blade is adequate, considering the shear adhesion strength of ice to different materials. The discovered knowledge is intended to increase the level of post-processing interpretation accuracy of experimental data obtained during the evaluation of ice-phobic materials for rotorcraft applications.

  16. Ultimate Strength of Wind Turbine Blades under Multiaxial Loading

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich

    loading effects and its influence on the ultimate strength of typical wind turbine rotor blade structures and to develop methods to perform reliable prediction of failure. For this purpose, origin and consequence of some of the typically occurring failure types in wind turbine rotor blades...... the ultimate strength of wind turbine rotor blades under multiaxial loadings. Failure origin and effects are studied numerically and experimentally with the purpose to investigate root causes of blade failure and to find generalities for their origin. The main contributions from this PhD study covering...... criteria are studied and their limitations demonstrated by comparing numerical and experimental results of a full scale blade loaded to ultimate failure. The main contributions from this PhD thesis dealing with failure origin and effects are the determination of generalities of failure. For buckling driven...

  17. 开式转子叶片气动设计研究%Research on Aerodynamic Design of Open Rotor Blade

    Institute of Scientific and Technical Information of China (English)

    刘政良; 严明; 洪青松

    2013-01-01

    参考现代民航飞机设计方案要求,完成了开式转子发动机叶片的气动设计工作。在设计过程中引入可压缩流动叶片数据改进了螺旋桨片条理论,使之适用于高亚声速来流的叶片设计。采用后掠叶片,NACA16系列叶型,前缘积叠方式。数值模拟结果与设计结果相近,基本满足气动设计要求。%Aerodynamic design of open rotor blade which refers to performance of engines which used on modern civil airplane is completed. Compressible blade data is introduced to optimize strip theory in order to satisfy blade design under high subsonic free stream. Sept blade, NACA-16 series data and leading edge accumulation is used. Numerical simulation is similar to the design which basicaly satisifed the design requirements.

  18. Design Framework for Vibration Monitoring Systems for Helicopter Rotor Blade Monitoring Using Wireless Sensor Networks

    NARCIS (Netherlands)

    Sanchez Ramirez, Andrea; Loendersloot, Richard; Jauregui Becker, Juan Manuel; Tinga, Tiedo; Chang, F.-K

    2013-01-01

    The pursue of methods for supporting Structural Health Monitoring (SHM) has been an important driver for the technological innovation in several engineering fields such as wireless communication, sensing and power harvesting. However, despite of the innovative and scientific value of these advances,

  19. Criteria for the provision and assembly of the rotor blades of a 300 MW low pressure steam turbine for electrical generation; Criterios para el suministro y ensambles de la alabes de rotor de turbina de vapor de 300 MW baja presion para generacion electrica

    Energy Technology Data Exchange (ETDEWEB)

    Bertin, Galo; Felix, Jorge A.; Quijano, Octavio [Especialistas en Turbopartes, S.A. de C.V., Queretaro, Queretaro (Mexico)

    2007-11-15

    This paper presents some of the main criteria to consider from the inspection, disassembling and assembly of blades with different root types of a turbine rotor of steam turbines for power generation, having as an aim to count on a reliable rotor, fulfilling with the equipment original design and norms and international standards. [Spanish] Este trabajo presenta algunos de los criterios principales a considerar desde la inspeccion, desmontaje y montaje de alabes de diferentes tipos de raiz de un rotor de turbinas de vapor de generacion electrica, teniendo como finalidad contar con un rotor confiable, cumpliendo con el diseno original del equipo y con normas y estandares internacionales.

  20. Rotor Vibration Reduction Using Multi-Element Multi-Path Design

    Science.gov (United States)

    Su, Keye

    Multi-Element Multi-Path (MEMP) structural design is a new concept for rotor vibration reduction. This thesis explores the possibility of applying MEMP design to helicopter rotor blades. A conceptual design is developed to investigate the MEMP blade's vibration reduction performance. In the design, the rotor blade is characterized by two centrifugally loaded beams which are connected to each other through linear and torsional springs. A computer program is built to simulate the behavior of such structures. Detailed parametric studies are conducted. The main challenges in this thesis involve the blade hub load vibration analysis, the blade thickness constraint and the blade parameter selection. The results show substantial vibration reduction for the MEMP design but the large relative deflection between the two beams, conceptualized as an internal spar and airfoil shell, remains a problem for further study.

  1. Blade attachment assembly

    Science.gov (United States)

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

    2016-05-03

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

  2. Modeling and design strategies for the vibration response of turbine engine rotors

    Science.gov (United States)

    Baik, Sanghum

    Efficient, novel design and analysis methods are presented for improving the structural performance of turbine engine rotors with respect to blade vibration response. For a bladed disk, the blades are intended to be identical; however, blade-to-blade structural irregularities, known as blade mistuning, in practice are unavoidable due to manufacturing tolerances and in-service wear. Even small levels of blade mistuning may cause severe increases in blade vibration amplitudes relative to those computed for the ideal, tuned rotor. Thus, the sensitivity of bladed disks to mistuning is a serious safety, readiness, and maintenance concern for turbine engines. Hereby, the effects of blade mistuning are systematically accounted for in searching for a reliable, robust rotor design; that is, a bladed disk less sensitive to mistuning. To this end, design analysis tools are developed for bladed disks. First, as an efficient tool for accurately predicting the vibration response of mistuned rotors, a previously developed reduced-order vibration modeling technique is extended to handle the case of mass mistuning. Even when mass mistuning occurs in small geometric regions of the blades, the enhanced technique can precisely capture free and forced vibration response of the mistuned rotors. Second, as a fast tool for approximately assessing mistuning sensitivity of rotors, a power flow analysis method is proposed. This approach enables the systematic estimation of vibration energy flow within a nominal rotor for excitation cases of interest. This dynamic information is then used to evaluate the robustness of the rotor design with respect to blade mistuning. These tools are incorporated into the design problem of finding an optimal disk geometry to achieve minimum weight while ensuring that blade stress levels of mistuned rotors are kept below a specified safety limit. In doing so, an optimum candidate satisfying the design constraints in an approximate sense is calculated quickly

  3. 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...... loading effects and its influence on the ultimate strength of typical wind turbine rotor blade structures and to develop methods to perform reliable prediction of failure. For this purpose, origin and consequence of some of the typically occurring failure types in wind turbine rotor blades...... are investigated. The research aims on predicting more accurately when and how blades fail under complex loading. The main contribution from this PhD study towards more reliable and robust operating wind turbine systems can be divided into two fields. One part covers numerical modelling approaches and the other...

  4. 悬浮弹旋翼结构参数对其气动力的影响分析%Impact Analysis of Suspension Bullets Rotors Structure Parameters to the Aerodynamic Force

    Institute of Scientific and Technical Information of China (English)

    苏京昭; 钱建平; 黄维平; 李定鹏; 郭淳

    2015-01-01

    针对现有文献在小型旋翼的气动力研究上的不足,建立一种旋翼升力与阻力的理论计算模型.基于旋翼叶素理论和矩形桨叶的拉力与阻力扭矩理论计算,采用CFD仿真的方法对其流场进行仿真,利用fluent软件建立旋翼流场的多参考系模型,通过理论计算和试验相结合的方法对其气动力CFD仿真结果进行对比分析,并计算不同结构参数的旋翼模型,得到了包括桨叶数目、桨叶翼型、旋翼半径、桨叶宽度和桨叶安装角的结构参数对其气动力的影响.仿真结果证明了该CFD方法用于小型旋翼流场仿真的可行性,为悬浮弹悬浮装置的设计中旋翼结构参数的选择提供了依据.%For lack of existing literature on the aerodynamic study of a small rotor, this paper established a theoretical model of rotors lift and drag simulation. Based on the rotors blade element theory and rectangular blade lift and drag torque theoretical calculationsusing CFD simulation method to simulate its flow field. Using FLUENT software to Establish multiple systems model of rotor flow field. Combined theoretical calculation and experiment phase to compare the aerodynamic simulation results of CFD to prove the feasibility of this method to study rotors flow field. Calculated the different structural parameters of the rotor model, obtained the influence of structural parameters including the number of blades, blades airfoil, rotors radius, blades mounting angle and blade width to rotors aerodynamic characteristics. The paper proved the feasibility of this CFD simulation method for small rotorcraft flow field and provided an evidence for the rotors structure parameters selection of suspended ammunition design.

  5. Rotor blades echo mo deling and mechanism analysis of flashes phenomena%旋翼叶片回波建模与闪烁现象机理分析

    Institute of Scientific and Technical Information of China (English)

    陈永彬; 李少东; 杨军; 曹芙蓉

    2016-01-01

    Since the rotorcraft can easily be recognized by using the micro-Doppler (m-D) signature of rotor blades, the m-D effect induced by micro-motion dynamics plays an important role in target recognition and classification. However, the existing researches on the rotor blades pay little attention to the mechanism of the time-domain and time-frequency-domain flash phenomena. To comprehensively explain the flash phenomena from physics, the modeling of the rotor blades and the mechanism of the flash phenomena are studied in this paper. Firstly, for the rotor blades, the target cannot be represented as a rigid, homogeneous line nor several points. Taking the scattering coefficients and the interval of adjacent scattering points (the scattering point distribution on the blade) into consideration, the scattering point model of the rotor blade echo is established, and the influence of the scattering point distribution on the radar echo is analyzed as well. The detailed mathematic analysis and comparison results show that the conventional integral model of the rotor blade is only a special case of the scattering point model. Furthermore, in the case where the scattering point model is approximately equivalent to the conventional integral model, the critical interval of adjacent scattering points is deduced by mathematic analysis. Secondly, on the basis of the proposed model above, the physical mechanism of the time-domain and time-frequency-domain flash phenomena is studied from the viewpoint of the electromagnetic (EM) scattering. On the one hand, considering the EM scattering and scattering point distribution, the mechanism of the time-domain flashes is analyzed. Ideally, when the rotor blade is at the vertical position relative to the radar line of sight, i.e., at the flash time, the blade has the strongest echo. At this moment, the radar echo consists of echoes of all scattering points, thus inducing the time-domain flashes. At the non-flash time, the scattering points at

  6. Open Rotor Development

    Science.gov (United States)

    Van Zante, Dale E.; Rizzi, Stephen A.

    2016-01-01

    The ERA project executed a comprehensive test program for Open Rotor aerodynamic and acoustic performance. System studies used the data to estimate the fuel burn savings and acoustic margin for an aircraft system with open rotor propulsion. The acoustic measurements were used to produce an auralization that compares the legacy blades to the current generation of open rotor designs.

  7. Efficiency of operation of wind turbine rotors optimized by the Glauert and Betz methods

    Science.gov (United States)

    Okulov, V. L.; Mikkelsen, R.; Litvinov, I. V.; Naumov, I. V.

    2015-11-01

    The models of two types of rotors with blades constructed using different optimization methods are compared experimentally. In the first case, the Glauert optimization by the pulsed method is used, which is applied independently for each individual blade cross section. This method remains the main approach in designing rotors of various duties. The construction of the other rotor is based on the Betz idea about optimization of rotors by determining a special distribution of circulation over the blade, which ensures the helical structure of the wake behind the rotor. It is established for the first time as a result of direct experimental comparison that the rotor constructed using the Betz method makes it possible to extract more kinetic energy from the homogeneous incoming flow.

  8. Blade loss transient dynamics analysis, volume 1. Task 1: Survey and perspective. [aircraft gas turbine engines

    Science.gov (United States)

    Gallardo, V. C.; Gaffney, E. F.; Bach, L. J.; Stallone, M. J.

    1981-01-01

    An analytical technique was developed to predict the behavior of a rotor system subjected to sudden unbalance. The technique is implemented in the Turbine Engine Transient Rotor Analysis (TETRA) computer program using the component element method. The analysis was particularly aimed toward blade-loss phenomena in gas turbine engines. A dual-rotor, casing, and pylon structure can be modeled by the computer program. Blade tip rubs, Coriolis forces, and mechanical clearances are included. The analytical system was verified by modeling and simulating actual test conditions for a rig test as well as a full-engine, blade-release demonstration.

  9. 拉挤复合材料在H型垂直轴风机叶片上的应用%Pultruded Composites in H- rotor Vertical Axis Wind Turbine Blade Application

    Institute of Scientific and Technical Information of China (English)

    刘森川; 王秋野; 王海芳

    2011-01-01

    H型垂直轴风机叶片是翼型等截面制品,采用拉挤复合材料能够满足其外形尺寸要求。本文主要分析了拉挤工艺生产叶片具有质量稳定、成本低、生产效率高等优点,同时也需要解决产品定型、叶片结构设计等问题。%H - rotor Vertical Axis Wind Turbine(VAWT) blade is uniform - section with aerofoil profile, and puhruded composites to meet the requirements of shape. Account for advantage of quality reliable, low cost and high efficiency. Also, some problems include finalized shape, structure design ,which need to be solved.

  10. 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...

  11. Experiment on blade pitch control of electrically controlled rotor based on adaptive filter control algorithm%基于自适应滤波的电控旋翼桨距控制试验

    Institute of Scientific and Technical Information of China (English)

    陆洋; 董维生; 洪亮; 冯剑波

    2012-01-01

    A new control algorithm based on the adaptive filter in time domain was brought forward.Based on this,the control system of electrically controlled rotor(ECR) blade pitch with double closed-loop was developed.Then,utilizing the test rig of model ECR,the pitch control experiments were performed in hover state.The experiments show that the developed control system of ECR blade pitch can work reliably through the tests.The control law based on the adaptive filter is successful in ECR collective pitch control,cyclic pitch control and collective pitch mixing with cyclic pitch control.The amplitude of the blade pitch was fitted well with the expected value,and the phase lag was about 10°~15°.The phase lag between the servo flap deflection and the response of blade pitch was about 20°~30°.Because of the structural and aerodynamic differences among different blades and servo flaps,the effect of blade pitch control will be reduced to some extent.%提出了基于自适应滤波的电控旋翼桨距控制方法,并基于此开发了双闭环电控旋翼桨距控制系统,利用模型电控旋翼试验台进行了悬停状态下的桨距控制试验.试验结果表明:所研制的双闭环电控旋翼桨距控制系统能够有效、可靠地实现襟翼操纵和桨距控制.基于自适应滤波的桨距控制律可以很好地实现电控旋翼的总距、周期变距以及总距祸合周期变距操纵;桨距响应幅值满足要求,相位滞后约在10~15之间;从襟翼偏转到桨叶变距响应的滞后约20~30,不同桨叶/襟翼自身的结构及气动特性差异,会一定程度的影响桨距控制的实际效果.

  12. Valve-aided twisted Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Jaya Rajkumar, M.; Saha, U.K.

    2006-05-15

    Accessories, such as end plates, deflecting plates, shielding and guide vanes, may increase the power of a Savonius rotor, but make the system structurally complex. In such cases, the rotor can develop a relatively large torque at small rotational speeds and is cheap to build, however it harnesses only a small fraction of the incident wind energy. Another proposition for increasing specific output is to place non-return valves inside the concave side of the blades. Such methods have been studied experimentally with a twisted-blade Thus improving a Savonius rotor's energy capture. This new concept has been named as the 'Valve-Aided Twisted Savonius'rotor. Tests were conducted in a low-speed wind tunnel to evaluate performance. This mechanism is found to be independent of flow direction, and shows potential for large machines. [Author].

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

    Directory of Open Access Journals (Sweden)

    Gębura Andrzej

    2015-12-01

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

  14. 涡流分级机转笼结构改进及内部流场数值模拟%Improvement on rotor cage structure of turbo air classifier and numerical simulation of inner flow field

    Institute of Scientific and Technical Information of China (English)

    黄强; 于源; 刘家祥

    2011-01-01

    In order to obtain fine powder with narrow particle size distribution and improve classification precision, the full blades in conventional rotor cages were improved to splitter style. The effect of the structure of the rotor cage with full blades and with splitter blades on the inner flow field of a turbo air classifier was investigated with the software Fluent. The result from numerical simulation indicates that air velocity fluctuations on outer cylinder of the improved rotor cage are decreased in the height direction,while, the radial velocity is decreased and the tangential velocity is increased compared with the conventional rotor cage, so the cut size of classified particles is smaller. The deviation of tangential velocity and radial velocity distribution on outer circle of horizontal section of the rotor cage is greatly improved,compared with the conventional rotor cage. When the ratio of the short blade length to the long blade length is 0.77, the flow field between blades is stable, and the velocity distribution on outer circle of the rotor cage is uniform. The experiment results on material classification demonstrate that the rotor cage with splitter blades is helpful to improving the classification precision and decreasing the cut size. The experimental result presents qualitative evidence for the CFD simulation and the feasibility in engineering applications.%@@ 引言 随着科技的进步,各行各业对粉体粒径和粒径分布的要求向细而窄的方向发展,因此对分级设备提出了高效、高精度的性能要求.涡流空气分级机是20世纪70年代末日本发明的,属于第三代动态干式分级机,具有能耗低、流场稳定等特点,广泛应用于建材、精细化工、食品、医药以及矿物加工等领域.

  15. Sensitivity of lag-damping correlations to structural and aerodynamic approximations of isolated experimental rotors in forward flight

    Science.gov (United States)

    Gaonkar, G. H.; Subramanian, S.; Chunduru, Srinivas

    1994-01-01

    The predictions of regressive lag-mode damping levels are correlated with the database of an isolated, soft-inplane, three-blade rotor operated untrimmed. The database was generated at the Army Aeroflightdynamics Directorate at Ames. The correlation covers a broad range of data, from near-zero thrust conditions in hover to high-thrust and highly stalled conditions in forward flight with advance ratio as high as 0.55 and shaft angle as high as 20 degrees. In the experimental rotor, the airfoil or blade portion has essentially uniform mass and stiffness distributions, but the root flexure has highly nonuniform mass and stiffness distributions. Accordingly, the structural approximations refer to four models of root-flexure-blade assembly. They range from a rigid flap-lag model to three elastic flap-lag-torsion models, which differ in modeling the root flexure. The three models of root-flexure are: three root springs in which the bending-torsion couplings are fully accounted for; a finite-length beam element with some average mass and stiffness distributions such that the fundamental frequencies match those of the experimental model; and accurate modal representation in which the actual mass and stiffness distributions of the experimental root-flexure-blade assembly are used in calculating the nonrotating mode shapes. The four models of root-flexure-blade assembly are referred to as the rigid flap-lag model, spring model, modified model and modal model. For each of these four models of the root-flexure-blade assembly, the predictions are based on the following five aerodynamic theories: ear theory, which accounts for large angle-of-attack and reverse-flow effects on lift, and has constant drag and pitching moment; quasisteady stall theory, which includes quasisteady stall lift, drag and pitching moment characteristics of the airfoil section, dynamics stall theory, which uses the ONERA dynamic stall models of lift, drag and pitching moment; dynamic wake theory, which is

  16. Recent results in characterisation and modeling of composites for wind turbine blades

    NARCIS (Netherlands)

    Nijssen, R.P.L.; Westphal, T.; Lahuerta Calahorra, F.; Van Delft, D.R.V.

    2013-01-01

    Wind turbine rotor blades are large structures which are designed to withstand extreme loading at low cost. Material and structural characterisation through modeling combined with tests are continuously developed to enable further design optimisation, larger rotors and new design concepts. This pape

  17. Manufacturing Methods and Technology (MANTECH) Program: Manufacturing Techniques for a Composite Main Rotor Blade for the Advanced Attack Helicopter

    Science.gov (United States)

    1982-04-01

    strip material. Readily available in sheet stock. Corrosion resistant easily formable. * A356 -T6 Aluminum - aft weight retention fitting. Material...graphite, fiberglass, resin, Nomex honeycomb, stainless steel, and aluminum mesh. The wet filament winding (WFW) fabrication process that is used to...blade. Narrow strips of aluminum screenwire bonded into the top and bottom skin near the trailing edge conduct lightning energy from the blade tip of

  18. Structural and Phase State of Fractured Rotor of High-Pressure Steam Turbine

    Science.gov (United States)

    Smirnov, A. N.; Ababkov, N. V.; Kozlov, E. V.; Koneva, N. A.; Popova, N. A.

    2016-03-01

    The structural and phase state of the metal of a fractured rotor of a steam turbine is studied with the use of modern methods of physical research. The metal is shown to contain gradient structures. The cause of the failure of the rotor is established. The gradient structures are determined by the developed method of acoustic scanning.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  20. Transonic Axial Splittered Rotor Tandem Stator Stage

    Science.gov (United States)

    2016-12-01

    compressor rotor was designed incorporating a splitter vane between the principal blades . Historical experiments conducted by Dr. Arthur J...conventional rotor design . The stage is composed of the rotor and stator. The flow of the air passing through the rotor is turned, and the flow is required...derived results achieved the best blade geometry for design continuation. The best circumferential and axial placement for the splitter blade was

  1. Aerodynamic optimization of wind turbine rotors using a blade element momentum method with corrections for wake rotation and expansion

    DEFF Research Database (Denmark)

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

    2012-01-01

    by the positive effect of wake rotation, which locally causes the efficiency to exceed the Betz limit. Wake expansion has a negative effect, which is most important at high tip speed ratios. It was further found that by using , it is possible to obtain a 5% reduction in flap bending moment when compared with BEM......The blade element momentum (BEM) method is widely used for calculating the quasi-steady aerodynamics of horizontal axis wind turbines. Recently, the BEM method has been expanded to include corrections for wake expansion and the pressure due to wake rotation (), and more accurate solutions can now...... be obtained in the blade root and tip sections. It is expected that this will lead to small changes in optimum blade designs. In this work, has been implemented, and the spanwise load distribution has been optimized to find the highest possible power production. For comparison, optimizations have been carried...

  2. Rotor for a pyrolysis centrifuge reactor

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a rotor for a pyrolysis centrifuge reactor, said rotor comprising a rotor body having a longitudinal centre axis, and at least one pivotally mounted blade being adapted to pivot around a pivot axis under rotation of the rotor body around the longitudinal centre axis....... Moreover, the present invention relates to a pyrolysis centrifuge reactor applying such a rotor....

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

    Science.gov (United States)

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

    1982-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-15

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

  5. Experimental Study of Endwall and Tip Clearance Flows in a Two—Dimensional Turbine Rotor Blade Cascade—Effect of Incidence Angle

    Institute of Scientific and Technical Information of China (English)

    M.Goardhan; B.H.L.Gowds; 等

    2000-01-01

    Experimental investigations were carried out on two-dimensional cascade fitted with a 120° deflecton rotor blades to study the effect of incidence angly on the endwall flow in the presence of tip clearance.A total of five incidence angles.namely:-10°,-5°,0°,5°,10°were chosen and for each incidence angle,the experiments were conducted for five tip clearance values at a constant space-chord ratio of 0.79,The experiments were conducted for five tip clearance values at a constant space-chord ratio of 0.79,The results are presented in the form of contours of static pressure coefficient on the endwall and the blade tip surface.In addition,the variation of static pressure coefficient ahead of the blade leading edge and from the pressure surface to the suction surface at various axial stations,and discharge coefficinet at different axial stations are presented.The results indicate that the adverse pressure gradient upstream of the leading edge is reduced as tip clearance is increased.The contours of static pressure coefficient on the endwall indicate a deep low-pressure trough near the suction surface in comparison to the normal trough for zero clearance,Loading also increases as incidence changes from the negative to positiv values,Due to area contraction caused by the tip separation vortex,the fluid moving towards the tip gap from the pressure side is accelerated.Downstream of the tip separation vortex,the endwall pressure increases due to flow mixing.The maximum value of discharge coefficient increases and the point at which maximum value occurs shifts towards leading edge when incidence is changed from-10°to 10°。

  6. Advanced turboprop aircraft flyover noise: Annoyance to counter-rotating-propeller configurations with a different number of blades on each rotor: Preliminary results

    Science.gov (United States)

    Mccurdy, David A.

    1988-01-01

    A laboratory experiment was conducted to quantify the annoyance of people to the flyover noise of advanced turboprop aircraft with counter-rotating propellers (CRP) having a different number of blades on each rotor (nxm, e.g., 10 x 8, 12 x 11). The objectives were: (1) compare annoyance to nxm CRP advanced turboprop aircraft with annoyance to conventional turboprop and jet aircraft; (2) determine the effects of tonal content on annoyance; and (3) determine the ability of aircraft noise measurement procedures and corrections to predict annoyance for this new class of aircraft. A computer synthesis system was used to generate 35 realistic, time-varying simulations of advanced turboprop takeoff noise in which the tonal content was systematically varied to represent combinations of 15 fundamental frequency (blade passage frequency) combinations and three tone-to-broadband noise ratios. The fundamental frequencies, which represented blade number combinations from 6 x 5 to 13 x 12 and 7 x 5 to 13 x 11, ranged from 112.5 to 292.5 Hz. The three tone-to-broadband noise ratios were 0, 15, and 30 dB. These advanced turboprop simulations along with recordings of five conventional turboprop takeoffs and five conventional jet takeoffs were presented at D-weighted sound pressure levels of 70, 80, and 90 dB to 64 subjects in an anechoic chamber. Analyses of the subjects' annoyance judgments compare the three categories of aircraft and examine the effects of the differences in tonal content among the advanced turboprop noises. The annoyance prediction ability of various noise measurement procedures and corrections is also examined.

  7. Fundamentals for remote structural health monitoring of wind turbine blades - a preproject

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Lading, L.; Sendrup, P.

    2002-01-01

    transducer was found to work well for detectingadhesive failure. Modelling work shows that damage in a wind turbine blade causes a significant change in the modal shape when the damage is in the or-der of 0.5-1 m. Rough estimates of the prices of complete sensor systems were made. The system based onacoustic......This summary-report describes the results of a pre-project that has the aim of estab-lishing the basic technical knowledge to evaluate whether remote surveillance of the rotor blades of large off-shore wind turbines has technical and economical potential.A cost-benefit analysis was developed......, showing that it is economically attractive to use sensors embedded in the blade. Specific technical requirements were defined for the sensors capability to detect the most important damage types in wind turbineblades. Three different sensor types were selected for use in laboratory experiments and full...

  8. Experimental Research and Numerical Analysis on Aerodynamic Characteristics of Rotors with Improved CLOR Blade-tip%改进型CLOR桨尖旋翼气动特性试验研究及数值分析

    Institute of Scientific and Technical Information of China (English)

    王博; 招启军; 赵国庆; 徐国华

    2013-01-01

    通过风洞试验及数值模拟对具有改进型CLOR(CLOR-Ⅱ)桨尖的旋翼悬停和前飞状态气动特性开展研究.在CLOR桨尖旋翼试验及数值分析的基础上,考虑旋翼非定常流场特点,兼顾旋翼悬停和前飞气动性能,对旋翼桨叶的气动外形进行了改进,主要包括采用多种翼型优化配置以综合改善旋翼前行侧压缩性及后行侧桨叶失速特性,并考虑旋翼前飞状态对其桨叶动力学特性的需求,重新设计了桨尖前后缘的外形.在风洞中分别对3种旋翼进行多种状态条件下的试验研究,为从流动细节上获得不同桨尖旋翼的气动特性差别,采用计算流体力学(CFD)方法对试验状态进行了数值模拟对比.对更高转速状态进行模拟,结果表明相对于其他两种旋翼,CLOR-Ⅱ桨尖旋翼在改善跨声速特性和提高失速迎角等方面具有明显优势,而且综合提高了旋翼悬停和前飞气动性能.%Wind tunnel test and numerical simulation are performed to investigate the aerodynamic characteristics of rotors with an improved CLOR (CLOR-Ⅱ )blade-tip in hover and forward flight. Taking into consideration the unsteady characteristics of the rotor flowfield, and aiming at advanced aerodynamic performance of the rotors in both hover and forward flight, the aerodynamic shape of the rotor blade is redesigned using aerodynamic analysis based on the investigations of rotors with CLOR tip. It mainly includes the optimal allocation of airfoils on the spanwise direction of the rotor blade for improving such properties as advancing blade compressibility and retreating blade dynamic stall, and the shape of the blade tip is designed meticulously taking into account the dynamic characteristics of the blade in forward flight. The three types of rotors are measured in a wind tunnel under multi-conditions. Based on these, the aerodynamic characteristics of rotors under the same ccmditions with the tests are simulated by computational

  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. Influence of backup bearings and support structure dynamics on the behavior of rotors with active supports

    Science.gov (United States)

    Flowers, George T.

    1995-02-01

    This semiannual status report lists specific accomplishments made on the research of the influence of backup bearings and support structure dynamics on the behavior of rotors with active supports. Papers have been presented representing work done on the T-501 engine model; an experimental/simulation study of auxiliary bearing rotordynamics; and a description of a rotordynamical model for a magnetic bearing supported rotor system, including auxiliary bearing effects. A finite element model for a foil bearing has been developed. Additional studies of rotor/bearing/housing dynamics are currently being performed as are studies of the effects of sideloading on auxiliary bearing rotordynamics using the magnetic bearing supported rotor model.

  11. Investigation of structural behaviour due to bend-twist couplings in wind turbine blades

    DEFF Research Database (Denmark)

    Fedorov, Vladimir; Dimitrov, Nikolay Krasimiroy; Berggreen, Christian;

    2009-01-01

    The structural behaviour of a composite wind turbine blade with implemented bend-twist coupling is examined in this paper. Several shell finite element models of the blade have been developed and validated against full-scale tests. All shell models performed well for flap-wise bending, but perfor......The structural behaviour of a composite wind turbine blade with implemented bend-twist coupling is examined in this paper. Several shell finite element models of the blade have been developed and validated against full-scale tests. All shell models performed well for flap-wise bending...

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

    CERN Document Server

    Chortis, Dimitris I

    2013-01-01

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

  13. Numerical study on air-structure coupling dynamic characteristics of the axial fan blade

    Science.gov (United States)

    Chen, Q. G.; Xie, B.; Li, F.; Gu, W. G.

    2013-12-01

    In order to understand the dynamic characteristics of the axial-flow fan blade due to the effect of rotating stress and the action of unsteady aerodynamic forces caused by the airflow, a numerical simulation method for air-structure coupling in an axial-flow fan with fixed rear guide blades was performed. The dynamic characteristics of an axial-flow fan rotating blade were studied by using the two-way air-structure coupling method. Based on the standard k-ε turbulence model, and using weak coupling method, the preceding six orders modal parameters of the rotating blade were obtained, and the distributions of stress and strain on the rotating blade were presented. The results show that the modal frequency from the first to the sixth order is 3Hz higher than the modal frequency without considering air-structure coupling interaction; the maximum stress and the maximum strain are all occurred in the vicinity of root area of the blade no matter the air-structure coupling is considered or not, thus, the blade root is the dangerous location subjected to fatigue break; the position of maximum deformation is at the blade tip, so the vibration of the blade tip is significant. This study can provide theoretical references for the further study on the strength analysis and mechanical optimal design.

  14. Dynamic Gust Load Analysis for Rotors

    Directory of Open Access Journals (Sweden)

    Yuting Dai

    2016-01-01

    Full Text Available Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.

  15. Design of the Active Elevon Rotor for Low Vibration

    Science.gov (United States)

    Fulton, Mark V.; Rutkowski, Michael (Technical Monitor)

    2000-01-01

    Helicopter fuselages vibrate more than desired, and traditional solutions have limited effectiveness and can impose an appreciable weight penalty. Alternative methods of combating high vibration, including Higher Harmonic Control (HHC) via harmonic swashplate motion and Individual Blade Control (IBC) via active pitch links, have been studied for several decades. HHC via an on-blade control surface was tested in 1977 on a full scale rotor using a secondary active swashplate and a mechanical control system. Recent smart material advances have prompted new research into the use of on-blade control concepts. Recent analytical studies have indicated that the use of on-blade control surfaces produces vibration reduction comparable to swashplate-based HHC but for less power. Furthermore, smart materials (such as piezoceramics) have been shown to provide sufficient control authority for preliminary rotor experiments. These experiments were initially performed at small scale for reduced tip speeds. More recent experiments have been conducted at or near full tip speeds, and a full-scale active rotor is under development by Boeing with Eurocopter et al. pursuing a similarly advanced full-scale implementation. The US Army Aeroflightdynamics Directorate has undertaken a new research program called the Active Elevon Rotor (AER) Focus Demo. This program includes the design, fabrication, and wind. tunnel testing of a four-bladed, 12.96 ft diameter rotor with one or two on-blade elevons per blade. The rotor, which will be Mach scaled, will use 2-5/rev elevon motion for closed-loop control and :will be tested in late 2001. The primary goal of the AER Focus Demo is the reduction of vibratory hub loads by 80% and the reduction of vibratory blade structural loads. A secondary goal is the reduction of rotor power. The third priority is the measurement and possible reduction of Blade Vortex Interaction (BVI) noise. The present study is focused on elevon effectiveness, that is, the elevon

  16. Multi-Objective Aerodynamic and Structural Optimization of Horizontal-Axis Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    2017-01-01

    Full Text Available A procedure based on MATLAB combined with ANSYS is presented and utilized for the multi-objective aerodynamic and structural optimization of horizontal-axis wind turbine (HAWT blades. In order to minimize the cost of energy (COE and improve the overall performance of the blades, materials of carbon fiber reinforced plastic (CFRP combined with glass fiber reinforced plastic (GFRP are applied. The maximum annual energy production (AEP, the minimum blade mass and the minimum blade cost are taken as three objectives. Main aerodynamic and structural characteristics of the blades are employed as design variables. Various design requirements including strain, deflection, vibration and buckling limits are taken into account as constraints. To evaluate the aerodynamic performances and the structural behaviors, the blade element momentum (BEM theory and the finite element method (FEM are applied in the procedure. Moreover, the non-dominated sorting genetic algorithm (NSGA II, which constitutes the core of the procedure, is adapted for the multi-objective optimization of the blades. To prove the efficiency and reliability of the procedure, a commercial 1.5 MW HAWT blade is used as a case study, and a set of trade-off solutions is obtained. Compared with the original scheme, the optimization results show great improvements for the overall performance of the blade.

  17. Structural Design of SynRM Rotor, and the Effect on Power Factor

    DEFF Research Database (Denmark)

    Henriksen, Matthew Lee; Jensen, Bogi Bech; Mijatovic, Nenad;

    2015-01-01

    In this paper, structural designs for multiple synchoronous reluctance machine (SynRM) rotor configurations are presented. The rotor flux bridges are increased in thickness until mechanical integrity is achieved, and then the performance of the resulting SynRM is observed. After performing this a...

  18. Structural Design of SynRM Rotor, and the Effect on Power Factor

    DEFF Research Database (Denmark)

    Henriksen, Matthew Lee; Jensen, Bogi Bech; Mijatovic, Nenad;

    2015-01-01

    In this paper, structural designs for multiple synchoronous reluctance machine (SynRM) rotor configurations are presented. The rotor flux bridges are increased in thickness until mechanical integrity is achieved, and then the performance of the resulting SynRM is observed. After performing...

  19. Structural Considerations of a 20MW Multi-Rotor Wind Energy System

    Science.gov (United States)

    Jamieson, P.; Branney, M.

    2014-12-01

    The drive to upscale offshore wind turbines relates especially to possiblereductions in O&M and electrical interconnection costs per MW of installed capacity.Even with best current technologies, designs with rated capacity above about 3 MW are less cost effective exfactory per rated MW(turbine system costs) than smaller machines.Very large offshore wind turbines are thereforejustifiedprimarily by overall offshore project economics. Furthermore, continuing progress in materials and structures has been essential to avoid severe penalties in the power/mass ratio of large multi-MW machines.The multi-rotor concept employs many small rotors to maximise energy capture area withminimum systemvolume. Previous work has indicated that this can enablea very large reduction in the total weight and cost of rotors and drive trains compared to an equivalent large single rotor system.Thus the multi rotor concept may enable rated capacities of 20 MW or more at a single maintenancesite. Establishing the cost benefit of a multi rotor system requires examination of solutions for the support structure and yawing, ensuring aerodynamic losses from rotor interaction are not significant and that overall logistics, with much increased part count (more reliable components) and less consequence of single failuresare favourable. This paper addresses the viability of a support structure in respect of structural concept and likely weight as one necessary step in exploring the potential of the multi rotor concept.

  20. 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.

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

    Science.gov (United States)

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

    2015-04-01

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

  2. Investigations for Improvement of Energy Yield of Rotor-blades from the 1.5 MW Class

    Science.gov (United States)

    Balaresque, N.; Bicker, S.; Dollinger, C.; Fandrich, A.; Gatz, S.; Hölling, M.; Irschik, K.; Reichstein, T.; Schaffarczyk, A. P.; von Zengen, C.

    2016-09-01

    In a combined approach of extensive measurement and accompanying simulation a wind turbine blade used in the 1.5 MW class was investigated for improvement of aerodynamic properties and especially the energy yield. One blade was dismantled and its geometry was locally measured by a specially designed laser scanning-system. From this geometry data set five 2D wind tunnel models were manufactured and measured in the wind tunnel of Deutsche Wind Guard Engineering GmbH at Bremerhaven, Germany. In addition, extensive CFD investigations were performed to investigate the usefulness of so-called aerodynamic devices like vortex generators, Gurney flaps and others for improving energy yield. As a result it could be shown that the aerodynamic efficiency of the manufactured blades - if measured in terms of lift-to-drag ratio - is at a high level but still can be further improved. 3D CFD investigations were able to show the influence of Gurney flaps and boundary layer fences and their interactions.

  3. Cooling of Gas Turbines I - Effects of Addition of Fins to Blade Tips and Rotor, Admission of Cooling Air Through Part of Nozzles, and Change in Thermal Conductivity of Turbine Components

    Science.gov (United States)

    Brown, Byron

    1947-01-01

    An analysis was developed for calculating the radial temperature distribution in a gas turbine with only the temperatures of the gas and the cooling air and the surface heat-transfer coefficient known. This analysis was applied to determine the temperatures of a complete wheel of a conventional single-stage impulse exhaust-gas turbine. The temperatures were first calculated for the case of the turbine operating at design conditions of speed, gas flow, etc. and with only the customary cooling arising from exposure of the outer blade flange and one face of the rotor to the air. Calculations were next made for the case of fins applied to the outer blade flange and the rotor. Finally the effects of using part of the nozzles (from 0 to 40 percent) for supplying cooling air and the effects of varying the metal thermal conductivity from 12 to 260 Btu per hour per foot per degree Farenheit on the wheel temperatures were determined. The gas temperatures at the nozzle box used in the calculations ranged from 1600F to 2000F. The results showed that if more than a few hundred degrees of cooling of turbine blades are required other means than indirect cooling with fins on the rotor and outer blade flange would be necessary. The amount of cooling indicated for the type of finning used could produce some improvement in efficiency and a large increase in durability of the wheel. The results also showed that if a large difference is to exist between the effective temperature of the exhaust gas and that of the blade material, as must be the case with present turbine materials and the high exhaust-gas temperatures desired (2000F and above), two alternatives are suggested: (a) If metal with a thermal conductivity comparable with copper is used, then the blade temperature can be reduced by strong cooling at both the blade tip and root. The center of the blade will be less than 2000F hotter than the ends; (b) With low conductivity materials some method of direct cooling other than

  4. 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.

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

    OpenAIRE

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

    2008-01-01

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

  6. Blade containment evaluation of civil aircraft engines

    Institute of Scientific and Technical Information of China (English)

    Yang Bin

    2013-01-01

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

  7. 涡流空气分级机圆弧形叶片转笼的设计%Design of Rotor Cage with Arc-blade for the Turbo Air Classifier

    Institute of Scientific and Technical Information of China (English)

    任文静; 刘家祥; 于源

    2016-01-01

    涡流空气分级机分级粒径主要受转笼转速与入口风速匹配关系的影响。入口风速一定时,转笼转速越高,分级粒径越小,但这会造成流场速度分布不均匀,而降低分级精度。利用Fluent软件对具有直叶片转笼结构的涡流空气分级机进行建模和数值模拟,分析转笼内流场特性,针对其流场不均匀及转笼入口冲角大等现象,对转笼叶片的形状及安装角进行改进,提出一种圆弧形叶片转笼的设计方法。通过数值模拟及物料试验对改进结果进行验证,数值模拟结果表明:圆弧形叶片转笼入口冲角减小,流道内流场更加均匀,分级粒径减小。碳酸钙分级试验结果与数值模拟结果吻合:设计工况即入口风速为12 m/s,转笼转速为1200 r/min时,采用设计的圆弧形叶片转笼在保持分级精度不变的情况下,分级粒径减小了11.5%。%The classification performance of a turbo air classifier is mainly affected by matching of air inlet velocity and rotating speed of rotor cage. With the same inlet velocity, increasing the rotating of rotor can decrease cut size to obtain ultra-fine powders. However, it will cause non-uniform distribution of fluid flow and decrease classifying accuracy. A model of the turbo air classifier with straight-blade rotor cage is established and the flow field is simulated by the software of Fluent. To solve the problems including non-uniform distribution of fluid flow and big angle of fluid-attack at the entrance of rotor cage, the blade’s shape and installation angle are designed and improved. A method of designing arc-blade rotor cage is proposed. The simulation results indicate that for the arc-blade rotor cage, the angle of fluid-attack at the entrance of rotor cage is decreased, the flow field of channel in rotor cage becomes uniform, and the cut size is also reduced. Calcium carbonate classification experimental results are in agreement with

  8. Design of an aeroelastically tailored 10 MW wind turbine rotor

    DEFF Research Database (Denmark)

    Zahle, Frederik; Tibaldi, Carlo; Pavese, Christian;

    2016-01-01

    This work presents an integrated multidisciplinary wind turbine optimization framework utilizing state-of-the-art aeroelastic and structural tools, capable of simultaneous design of the outer geometry and internal structure of the blade. The framework is utilized to design a 10 MW rotor constrained...... not to exceed the design loads of an existing reference wind turbine. The results show that through combined geometric tailoring of the internal structure and aerodynamic shape of the blade it is possible to achieve significant passive load alleviation that allows for a 9% longer blade with an increase in AEP...

  9. 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.

  10. Experimental Study of Active Techniques for Blade/Vortex Interaction Noise Reduction

    Science.gov (United States)

    Kobiki, Noboru; Murashige, Atsushi; Tsuchihashi, Akihiko; Yamakawa, Eiichi

    This paper presents the experimental results of the effect of Higher Harmonic Control (HHC) and Active Flap on the Blade/Vortex Interaction (BVI) noise. Wind tunnel tests were performed with a 1-bladed rotor system to evaluate the simplified BVI phenomenon avoiding the complicated aerodynamic interference which is characteristically and inevitably caused by a multi-bladed rotor. Another merit to use this 1-bladed rotor system is that the several objective active techniques can be evaluated under the same condition installed in the same rotor system. The effects of the active techniques on the BVI noise reduction were evaluated comprehensively by the sound pressure, the blade/vortex miss distance obtained by Laser light Sheet (LLS), the blade surface pressure distribution and the tip vortex structure by Particle Image Velocimetry (PIV). The correlation among these quantities to describe the effect of the active techniques on the BVI conditions is well obtained. The experiments show that the blade/vortex miss distance is more dominant for BVI noise than the other two BVI governing factors, such as blade lift and vortex strength at the moment of BVI.

  11. Novel Compressor Blade Design Study

    Science.gov (United States)

    Srinivas, Abhay

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

  12. 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.

  13. Advanced turboprop aircraft flyover noise: Annoyance to counter-rotating-propeller configurations with an equal number of blades on each rotor, preliminary results

    Science.gov (United States)

    Mccurdy, David A.

    1988-01-01

    A laboratory experiment was conducted to quantify the annoyance of people to the flyover noise of advanced turboprop aircraft with counter-rotating propellers (CRP) having an equal number of blades on each rotor. The objectives were: to determine the effects of total content on annoyance; and compare annoyance to n x n CRP advanced turboprop aircraft with annoyance to conventional turboprop and jet aircraft. A computer synthesis system was used to generate 27 realistic, time-varying simulations of advanced turboprop takeoff noise in which the tonal content was systematically varied to represent the factorial combinations of nine fundamental frequencies and three tone-to-broadband noise ratios. These advanced turboprop simulations along with recordings of five conventional turboprop takeoffs and five conventional jet takeoffs were presented at three D-weighted sound pressure levels to 64 subjects in an anechoic chamber. Analyses of the subjects' annoyance judgments compare the three aircraft types and examined the effects of the differences in tonal content among the advanced turboprop noises. The annoyance prediction ability of various noise metrics is also examined.

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

    Science.gov (United States)

    Dey, Soumitr

    2011-12-01

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

  15. Energetics and electronic structure of nanoscale rotors consisting of triptycene and hydrocarbon molecules

    Science.gov (United States)

    Akiba, Miki; Okada, Susumu

    2017-10-01

    Using the density functional theory with generalized gradient approximation, we studied the energetics and electronic structures of nanoscale rotors consisting of tryptycene and hydrocarbon molecules with respect to their mutual orientation. Energy barriers for the rotational motion of an attached hydrocarbon molecule range from 40 to 200 meV, depending on the attached molecular species and arrangements. The electronic structure of the nanoscale molecular rotors does not depend on the rotational angle of the attached hydrocarbon molecules.

  16. Aeroelastic Behavior of a Wind Turbine Blade by a Fluid -Structure Interaction Analysis

    Directory of Open Access Journals (Sweden)

    Farouk O. Hamdoon

    2013-01-01

    Full Text Available In this paper, a numerical model for fluid-structure interaction (FSI analysis is developed for investigating the aeroelastic response of a single wind turbine blade. The Blade Element Momentum (BEM theory was adopted to calculate the aerodynamic forces considering the effects of wind shear and tower shadow. The wind turbine blade was modeled as a rotating cantilever beam discretized using Finite Element Method (FEM to analyze the deformation and vibration of the blade. The aeroelastic response of the blade was obtained by coupling these aerodynamic and structural models using a coupled BEM-FEM program written in MATLAB. The governing FSI equations of motion are iteratively calculated at each time step, through exchanging data between the structure and fluid by using a Newmark’s implicit time integration scheme. The results obtained from this paper show that the proposed modeling can be used for a quick assessment of the wind turbine blades taking the fluid-structure interaction into account. This modeling can also be a useful tool for the analysis of airplane propeller blades.

  17. Reducing rotor weight

    Energy Technology Data Exchange (ETDEWEB)

    Cheney, M.C. [PS Enterprises, Inc., Glastonbury, CT (United States)

    1997-12-31

    The cost of energy for renewables has gained greater significance in recent years due to the drop in price in some competing energy sources, particularly natural gas. In pursuit of lower manufacturing costs for wind turbine systems, work was conducted to explore an innovative rotor designed to reduce weight and cost over conventional rotor systems. Trade-off studies were conducted to measure the influence of number of blades, stiffness, and manufacturing method on COE. The study showed that increasing number of blades at constant solidity significantly reduced rotor weight and that manufacturing the blades using pultrusion technology produced the lowest cost per pound. Under contracts with the National Renewable Energy Laboratory and the California Energy Commission, a 400 kW (33m diameter) turbine was designed employing this technology. The project included tests of an 80 kW (15.5m diameter) dynamically scaled rotor which demonstrated the viability of the design.

  18. Open Rotor Aeroacoustic Modelling

    Science.gov (United States)

    Envia, Edmane

    2012-01-01

    Owing to their inherent fuel efficiency, there is renewed interest in developing open rotor propulsion systems that are both efficient and quiet. The major contributor to the overall noise of an open rotor system is the propulsor noise, which is produced as a result of the interaction of the airstream with the counter-rotating blades. As such, robust aeroacoustic prediction methods are an essential ingredient in any approach to designing low-noise open rotor systems. To that end, an effort has been underway at NASA to assess current open rotor noise prediction tools and develop new capabilities. Under this effort, high-fidelity aerodynamic simulations of a benchmark open rotor blade set were carried out and used to make noise predictions via existing NASA open rotor noise prediction codes. The results have been compared with the aerodynamic and acoustic data that were acquired for this benchmark open rotor blade set. The emphasis of this paper is on providing a summary of recent results from a NASA Glenn effort to validate an in-house open noise prediction code called LINPROP which is based on a high-blade-count asymptotic approximation to the Ffowcs-Williams Hawkings Equation. The results suggest that while predicting the absolute levels may be difficult, the noise trends are reasonably well predicted by this approach.

  19. Optimization of wind turbine rotors

    Energy Technology Data Exchange (ETDEWEB)

    Nygaard, Tor Anders

    1999-07-01

    The Constrained Steepest Descent method has been applied to the optimization of wind turbine rotors through the development of a numerical model. The model consists of an optimization kernel, an aerodynamic model, a structural dynamic model of a rotating beam, and a cost model for the wind turbine. The cost of energy is minimized directly by varying the blade design, the rotational speed and the resulting design of the drive-train and tower. The aerodynamic model is a combination of a fast engineering model based on strip-theory and two and three-dimensional Euler solvers. The two-dimensional Euler solver is used for generation of pre-stall airfoil data. Comparisons with experimental data verify that the engineering model effectively approximates non-stalled flow, except at the blade tip. The three-dimensional Euler solver is in good agreement with the experimental data at the tip, and is therefore a useful supplement for corrections of the tip-loss model, and evaluation of an optimized design. The structural dynamic model evaluates stresses and deformations for the blade. It is based on constitutive relations for a slender beam that are solved with the equations of motions using a finite-difference method. The cost model evaluates the design change of the wind turbine and the resulting costs that occur when a change in blade design modifies the blade mass and the overall forces. The cost model is based on engineering design rules for the drive-train and tower. The model was applied using a Danish 600 kW wind turbine as a reference. Two rotors were optimized using traditional NACA airfoils and a new low-lift airfoil family developed specifically for wind turbine purposes. The cost of energy decreased four percent for the NACA rotor, and seven percent for the low-lift rotor. Optimizations with a high number of degrees of freedom show that a designer has considerable flexibility in choosing some primary parameters such as rated power and rotor diameter, if the rest

  20. 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.

  1. 基于PCNN的桨叶图像提取及锥度测量%A New Method for Rotor Blade Image Extraction Based on PCNN and Pyramid Angle measurement

    Institute of Scientific and Technical Information of China (English)

    姜迈; 蔡成涛; 邓超; 栗蓬

    2011-01-01

    针对目前对直升机桨叶共锥度测量难度大、精度低、无法对桨叶逐点测量的缺点,提出了一种应用视觉系统测量旋翼共锥度的新方法,给出了系统的总体安装方案并对系统的成像误差精度进行了分析,由于旋翼桨叶处于高速旋转状态需要实时处理的特点,提出了一种基于脉冲藕合神经网络(PCNN)的分割方法,在设计好的旋翼桨叶模型上进行了相关实验,通过与其它分割算法的对比,验证了算法的具有很高的识别率;实验结果表明:基于PCNN的分割方法具有较高的精度,适用于实时的旋翼锥度测量系统.%According to the problems for helicopter blades pyramid angle measurement, such as great difficulty of the measuring, low accuracy and thoroughly examination hardly, this paper presents a new method applied to helicopter blade pyramid angle measurement by using vision system, the overall design scheme of the system is offered and the imaging error is analyzed.Because the rotor blades rotated at a high speed and need real-time processing, proposes a image segmentation method based on Pulse Couple Neural Network (PCNN), the related experiment to the rotor blades model validates the PCNN algorithm has the advantage in recognition rate compared with other segmentation algorithms.The experimental results show the method has higher accuracy and suitable for blades pyramid measurement system.

  2. Influence of different rotor magnetic circuit structure on the performance of permanent magnet synchronous motor

    Directory of Open Access Journals (Sweden)

    Qiu Hongbo

    2017-09-01

    Full Text Available In order to compare the performance difference of the permanent magnet synchronous motors (PMSM with different rotor structure, two kinds of rotor magnetic circuit structure with surface-mounted radial excitation and tangential excitation are designed respectively. By comparing and analyzing the results, the difference of the motor performance was determined. Firstly, based on the finite element method (FEM, the motor electromagnetic field performance was studied, and the magnetic field distribution of the different magnetic circuit structure was obtained. The influence mechanism of the different magnetic circuit structure on the air gap flux density was obtained by using the Fourier theory. Secondly, the cogging torque, output torque and overload capacity of the PMSM with different rotor structure were studied. The effect mechanism of the different rotor structure on the motor output property difference was obtained. The motor prototype with two kinds of rotor structure was manufactured, and the experimental study was carried out. By comparing the experimental data and simulation data, the correctness of the research is verified. This paper lays a foundation for the research on the performance of the PMSM with different magnetic circuit structure.

  3. 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)

  4. 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.

  5. Fundamentals for remote structural health monitoring of wind turbine blades - a pre-project

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, B.F.; Lading, L.; Sendrup, P. (and others)

    2002-05-01

    This summary-report describes the results of a pre-project that has the aim of establishing the basic technical knowledge to evaluate whether remote surveillance of the rotor blades of large off-shore wind turbines has technical and economical potential. A cost-benefit analysis was developed, showing that it is economically attractive to use sensors embedded in the blade. Specific technical requirements were defined for the sensors capability to detect the most important damage types in wind turbine blades. Three different sensor types were selected for use in laboratory experiments and full-scale tests of a wind turbine blade developing damage: 1) detection of stress wave emission by acoustic emission, 2) measurement of modal shape changes by accelerometers and 3) measurement of crack opening of adhesive joint by a fibre optics micro-bend displacement transducer that was developed in the project. All types of sensor approaches were found to work satisfactory. The techniques were found to complement each other: Acoustic emission has the capability of detecting very small damages and can be used for locating the spatial position and size of evolving damages. The fibre optics displacement transducer was found to work well for detecting adhesive failure. Modelling work shows that damage in a wind turbine blade causes a significant change in the modal shape when the damage is in the order of 0.5-1 m. Rough estimates of the prices of complete sensor systems were made. The system based on acoustic emission was the most expensive and the one based on accelerometers was the cheapest. NDT methods (ultrasound scanning and X-ray inspection) were found to be useful for verification of hidden damage. Details of the work are described in annexes. (au)

  6. The Smart Rotor Concept on Wind Turbines - Actuators and Structures

    NARCIS (Netherlands)

    Hulskamp, A.W.

    2011-01-01

    Wind turbines suffer heavily from fatigue loads but current load control concepts are not effective in mitigating them. This thesis contributes to the development of a novel concept in which the air flow over the blade is controlled through spanwise distributed devices. The work is aimed at implemen

  7. Lightweight rotor design by optimal spar cap offset

    Science.gov (United States)

    Croce, A.; Sartori, L.; Lunghini, M. S.; Clozza, L.; Bortolotti, P.; Bottasso, C. L.

    2016-09-01

    Bend-twist coupling behavior is induced in a blade by displacing the suction side spar cap towards the leading edge, and the pressure side one in the opposite direction. Additional couplings are introduced by rotating the spar cap fibers. The structural configuration of the blade is optimized using an automated design environment. The resulting blade shows significant benefits in terms of mass and loads when compared to the baseline uncoupled one. Finally, the lightweight design concept is used to increase the rotor size, resulting in a larger energy yield for the same hub loads.

  8. Fluid Structural Modal Coupled Numerical Investigation of Transonic Fluttering Of Axial Flow Compressor Blades

    Directory of Open Access Journals (Sweden)

    Rio Melvin Aro.T

    2015-05-01

    Full Text Available Flutter is an unstable oscillation which can lead to destruction. Flutter can occur on fixed surfaces, such as blades, wing or the stabilizer. By self-excited aeroelastic instability, flutter can lead to mechanical or structural failure of aircraft engine blades. The modern engines have been designed with increased pressure ratio and reduced weight in order to improve aerodynamic efficiency, resulting in severe aeroelastic problems. Particularly flutter in axial compressors with transonic flow can be characterized by a number of aerodynamic nonlinear effects such as shock boundary layer interaction, rotating stall, and tip vortex instability. Rotating blades operating under high centrifugal forces may also encounter structural nonlinearities due to friction damping and large deformations. In the future work a standard axial flow compressor blade will be taken for analysis, both Subsonic and Transonic range are taken for analysis. Fluid and Structure are two different domains which will be coupled by full system coupling technique to predict the fluttering effect on the compressor blade. ANSYS is a commercial simulation tool, which will be deployed in this work to perform FSI (Fluid Structure Interaction and FSI coupled Modal to predict the flutter in the compressor blades

  9. A coupled aero-structural model of a HAWT blade for dynamic load and response prediction in time-domain for health monitoring applications

    Science.gov (United States)

    Sauder, Heather Scot

    To reach the high standards set for renewable energy production in the US and around the globe, wind turbines with taller towers and longer blades are being designed for onshore and offshore wind developments to capture more energy from higher winds aloft and a larger rotor diameter. However, amongst all the wind turbine components wind turbine blades are still the most prone to damage. Given that wind turbine blades experience dynamic loads from multiple sources, there is a need to be able to predict the real-time load, stress distribution and response of the blade in a given wind environment for damage, flutter and fatigue life predictions. Current methods of wind-induced response analysis for wind turbine blades use approximations that are not suitable for wind turbine blade airfoils which are thick, and therefore lead to inaccurate life predictions. Additionally, a time-domain formulation can prove to be especially advantageous for predicting aerodynamic loads on wind turbine blades since they operate in a turbulent atmospheric boundary layer. This will help to analyze the blades on wind turbines that operate individually or in a farm setting where they experience high turbulence in the wake of another wind turbine. A time-domain formulation is also useful for examining the effects of gusty winds that are transient in nature like in gust fronts, thunderstorms or extreme events such as hurricanes, microbursts, and tornadoes. Time-domain methods present the opportunity for real-time health monitoring strategies that can easily be used with finite element methods for prediction of fatigue life or onset of flutter instability. The purpose of the proposed work is to develop a robust computational model to predict the loads, stresses and response of a wind turbine blade in operating and extreme wind conditions. The model can be used to inform health monitoring strategies for preventative maintenance and provide a realistic number of stress cycles that the blade will

  10. Flow Field Characteristics of the Rotor Cage in Turbo Air Classifiers

    Institute of Scientific and Technical Information of China (English)

    GUO Lijie; LIU Jiaxiang; LIU Shengzhao

    2009-01-01

    The turbo air classifier is widely used powder classification equipment in a variety of fields. The flow field characteristics of the turbo air classifier are important basis for the improvement of the turbo air classifier's structural design. The flow field characteristics of the rotor cage in turbo air classifiers were investigated under different operating conditions by laser Doppler velocimeter(LDV), and a measure diminishing the axial velocity is proposed. The investigation results show that the tangential velocity of the air flow inside the rotor cage is different from the rotary speed of the rotor cage on the same measurement point due to the influences of both the negative pressure at the exit and the rotation of the rotor cage. The tangential velocity of the air flow likewise decreases as the radius decreases in the case of the rotor cage's low rotary speed. In contrast, the tangential velocity of the air flow increases as the radius decreases in the case of the rotor cage's high rotary speed. Meanwhile, the vortex inside the rotor cage is found to occur near the pressure side of the blade when the rotor cage's rotary speed is less than the tangential velocity of air flow. On the contrary, the vortex is found to occur near the blade suction side once the rotor cage's rotary speed is higher than the tangential velocity of air flow. Inside the rotor cage, the axial velocity could not be disregarded and is largely determined by the distances between the measurement point and the exit.

  11. Fatigue degradation and failure of rotating composite structures - Materials characterisation and underlying mechanisms

    DEFF Research Database (Denmark)

    Gamstedt, Kristofer; Andersen, Svend Ib Smidt

    2001-01-01

    The present review concerns rotating composite structures, in which fatigue degradation is of key concern for in-service failure. Such applications are for instance rotor blades in wind turbines, helicopter rotor blades, flywheels for energy storage,marine and aeronautical propellers, and rolls...

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

    Coroneos, Rula M.; Gorla, Rama Subba Reddy

    2012-09-01

    This paper addresses the structural analysis and optimization of a composite sandwich ply lay-up of a NASA baseline solid metallic fan blade comparable to a future Boeing 737 MAX aircraft engine. Sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replaces 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 where as the overall blade thickness is held fixed in order not to alter the original airfoil geometry. Weight reduction is taken as the objective function 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.

  14. Optimization design of Savonius diffuser blade with moving deflector for hydrokınetıc cross flow turbıne rotor

    NARCIS (Netherlands)

    Wahjudi, B.; Soeparman, S.B.; Hoeijmakers, H.W.M.; bin Abu Bakar, Rosli; Froome, Craig

    2015-01-01

    The conventional Savonius turbine is a good concept for small size wind-renewable energy systems; unfortunately always it has low efficiency. Inspired from the Savonius Blade, this research project designed the diffuser form as compartment between S blade and Tandem Blade of Savonius to produce “jet

  15. Optimization design of Savonius diffuser blade with moving deflector for hydrokınetıc cross flow turbıne rotor

    NARCIS (Netherlands)

    Wahjudi, B.; Soeparman, S.B.; Hoeijmakers, Hendrik Willem Marie; bin Abu Bakar, Rosli; Froome, Craig

    2015-01-01

    The conventional Savonius turbine is a good concept for small size wind-renewable energy systems; unfortunately always it has low efficiency. Inspired from the Savonius Blade, this research project designed the diffuser form as compartment between S blade and Tandem Blade of Savonius to produce “jet

  16. An aerodynamic study on flexed blades for VAWT applications

    Science.gov (United States)

    Micallef, Daniel; Farrugia, Russell; Sant, Tonio; Mollicone, Pierluigi

    2014-12-01

    There is renewed interest in aerodynamics research of VAWT rotors. Lift type, Darrieus designs sometimes use flexed blades to have an 'egg-beater shape' with an optimum Troposkien geometry to minimize the structural stress on the blades. While straight bladed VAWTs have been investigated in depth through both measurements and numerical modelling, the aerodynamics of flexed blades has not been researched with the same level of detail. Two major effects may have a substantial impact on blade performance. First, flexing at the equator causes relatively strong trailing vorticity to be released. Secondly, the blade performance at each station along the blade is influenced by self-induced velocities due to bound vorticity. The latter is not present in a straight bladed configuration. The aim of this research is to investigate these effects in relation to an innovative 4kW wind turbine concept being developed in collaboration with industry known as a self-adjusting VAWT (or SATVAWT). The approach used in this study is based on experimental and numerical work. A lifting line free-wake vortex model was developed. Wind tunnel power and hot-wire velocity measurements were performed on a scaled down, 60cm high, three bladed model in a closed wind tunnel. Results show a substantial axial wake induction at the equator resulting in a lower power generation at this position. This induction increases with increasing degree of flexure. The self-induced velocities caused by blade bound vorticity at a particular station was found to be relatively small.

  17. Optimization Method for Girder of Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Yuqiao Zheng

    2014-01-01

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

  18. Morphing Downwind-Aligned Rotor Concept Based on a 13-MW Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Ichter, Brian; Steele, Adam; Loth, Eric; Moriarty, Patrick; Selig, Michael

    2016-04-01

    To alleviate the mass-scaling issues associated with conventional upwind rotors of extreme-scale wind turbines (>/=10 MW), a morphing downwind-aligned rotor (MoDaR) concept is proposed herein. The concept employs a downwind rotor with blades whose elements are stiff (no intentional flexibility) but with hub-joints that can be unlocked to allow for moment-free downwind alignment. Aligning the combination of gravitational, centrifugal and thrust forces along the blade path reduces downwind cantilever loads, resulting in primarily tensile loading. For control simplicity, the blade curvature can be fixed with a single morphing degree of freedom using a near-hub joint for coning angle: 22 degrees at rated conditions. The conventional baseline was set as the 13.2-MW Sandia 100-m all glass blade in a three-bladed upwind configuration. To quantify potential mass savings, a downwind load-aligning, two-bladed rotor was designed. Because of the reduced number of blades, the MoDaR concept had a favorable 33% mass reduction. The blade reduction and coning led to a reduction in rated power, but morphing increased energy capture at lower speeds such that both the MoDaR and conventional rotors have the same average power: 5.4 MW. A finite element analysis showed that quasi-steady structural stresses could be reduced, over a range of operating wind speeds and azimuthal angles, despite the increases in loading per blade. However, the concept feasibility requires additional investigation of the mass, cost and complexity of the morphing hinge, the impact of unsteady aeroelastic influence because of turbulence and off-design conditions, along with system-level Levelized Cost of Energy analysis.

  19. A Study on Structural Design and Analysis of Blade and Tower for Small Wind Turbine System

    Directory of Open Access Journals (Sweden)

    Park Hyunbum

    2016-01-01

    Full Text Available This paper performed aerodynamic, structural design and analysis of the horizontal axis blade of low noise 1kW class small wind turbine system that can be operated at homes and designed to display excellent performances in low wind velocity regions such as Korea. In terms of the material applied, glass/epoxy that is both economical and excellent in its performance was applied. Structural test was conducted to verify whether the actual movement of the blade designed is consistent with the theoretical analysis result. In addition, structural safety review was performed through the structural analysis of a tower for installing the wind turbine system developed.

  20. 核电厂汽轮机转子叶片的荧光磁粉检测%Fluorescent Magnetic Particle Inspection for Nuclear Power Plant Turbine Rotor Blades

    Institute of Scientific and Technical Information of China (English)

    付千发; 李朋; 李邱达; 葛亮; 张明

    2015-01-01

    This paper introduces the steps and technical requirements for the fluorescent magnetic particle testing of steam turbine rotor blade by using the method of coil and magnetic yoke.Suitable technological parameters for the test were identified through experiment and the actual testing of steam turbine rotor blade was performed,and at the same time a contrast experiment was made with penetration detection.The test showed that the fluorescent magnetic particle detection method could effectively detect smaller defects in the blade end,root and surface of the leaf body with high sensitivity and high reliability for in-service inspection of blade and other irregular shape of products.%介绍了使用线圈法和磁轭法对汽轮机转子叶片进行荧光磁粉检测的步骤及技术要求。通过试验确定了合适的检测工艺,并对汽轮机转子叶片进行了实际检测,同时进行了与渗透检测的对比试验,试验表明:荧光磁粉检测法能有效检出叶片端部、齿根及叶身表面的较小缺陷,具有较高的检出灵敏度,可靠性较高,适用于叶片类不规则形状产品的在役检验。

  1. Boeing Smart Rotor Full-scale Wind Tunnel Test Data Report

    Science.gov (United States)

    Kottapalli, Sesi; Hagerty, Brandon; Salazar, Denise

    2016-01-01

    A full-scale helicopter smart material actuated rotor technology (SMART) rotor test was conducted in the USAF National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel at NASA Ames. The SMART rotor system is a five-bladed MD 902 bearingless rotor with active trailing-edge flaps. The flaps are actuated using piezoelectric actuators. Rotor performance, structural loads, and acoustic data were obtained over a wide range of rotor shaft angles of attack, thrust, and airspeeds. The primary test objective was to acquire unique validation data for the high-performance computing analyses developed under the Defense Advanced Research Project Agency (DARPA) Helicopter Quieting Program (HQP). Other research objectives included quantifying the ability of the on-blade flaps to achieve vibration reduction, rotor smoothing, and performance improvements. This data set of rotor performance and structural loads can be used for analytical and experimental comparison studies with other full-scale rotor systems and for analytical validation of computer simulation models. The purpose of this final data report is to document a comprehensive, highquality data set that includes only data points where the flap was actively controlled and each of the five flaps behaved in a similar manner.

  2. Vibration Reduction Methods and Techniques for Rotorcraft Utilizing On-Blade Active Control Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Rotor blades adapted for vibration control have the added benefit of extended blade and rotor life, as well as improved passenger comfort. Approaches that have been...

  3. Pneumatic boot for helicopter rotor deicing

    Science.gov (United States)

    Blaha, B. J.; Evanich, P. L.

    1981-01-01

    Pneumatic deicer boots for helicopter rotor blades were tested. The tests were conducted in the 6 by 9 ft icing research tunnel on a stationary section of a UH-IH helicopter main rotor blade. The boots were effective in removing ice and in reducing aerodynamic drag due to ice.

  4. Passive damping of composite blades using embedded piezoelectric modules or shape memory alloy wires: a comparative study

    Science.gov (United States)

    Bachmann, F.; de Oliveira, R.; Sigg, A.; Schnyder, V.; Delpero, T.; Jaehne, R.; Bergamini, A.; Michaud, V.; Ermanni, P.

    2012-07-01

    Emission reduction from civil aviation has been intensively addressed in the scientific community in recent years. The combined use of novel aircraft engine architectures such as open rotor engines and lightweight materials offer the potential for fuel savings, which could contribute significantly in reaching gas emissions targets, but suffer from vibration and noise issues. We investigated the potential improvement of mechanical damping of open rotor composite fan blades by comparing two integrated passive damping systems: shape memory alloy wires and piezoelectric shunt circuits. Passive damping concepts were first validated on carbon fibre reinforced epoxy composite plates and then implemented in a 1:5 model of an open rotor blade manufactured by resin transfer moulding (RTM). A two-step process was proposed for the structural integration of the damping devices into a full composite fan blade. Forced vibration measurements of the plates and blade prototypes quantified the efficiency of both approaches, and their related weight penalty.

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

    Science.gov (United States)

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

    2017-02-01

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

  6. 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.

  7. Smart Rotor Modeling: Aero-Servo-Elastic Modeling of a Smart Rotor with Adaptive Trailing Edge Flaps

    DEFF Research Database (Denmark)

    Bergami, Leonardo

    This book presents the formulation of an aero-servo-elastic model for a wind turbine rotor equipped with Adaptive Trailing Edge Flaps (ATEF), a smart rotor configuration. As the name suggests, an aero-servo-elastic model consists of three main components: an aerodynamic model, a structural model......, and a control model. The book first presents an engineering type of aerodynamic model that accounts for the dynamic effects of flap deflection. The aerodynamic model is implemented in a Blade Element Momentum framework, and coupled with a multi-body structural model in the aero-servoelastic simulation code HAWC...... the trailing edge flap deflection to actively reduce the fatigue loads on the structure. The performance of the smart rotor configuration and its control algorithms are finally quantified by aero-servo-elastic simulations of the smart rotor turbine operating in a standard turbulent wind field....

  8. A study on static structural of non-rotor unmanned aerial vehicle

    Directory of Open Access Journals (Sweden)

    Chen Yu-Lan

    2017-01-01

    Full Text Available Multi-rotor unmanned aerial vehicles (UAVs have become common in recent years, but non-rotor UAVs are still relatively rare. This study used an aerodynamic model to replace the multi-rotor design concept and examine load bearing capabilities, specifically for delivery of medical goods by non-rotor UAV. We use static structural simulations for static analysis and fatigue analysis to investigate the capabilities of different structural materials. The simulation results combined fatigue strength verifications, structural safety factor calculations, and finite element analyses to calculate parameters like total deformation, stress ratios, and strain magnitudes to analyze structural fatigue life. The analyses indicated that the factors of safety and fatigue lifetimes of two structural materials far exceeded standard values. They can be used to optimize designs that prevent plastic deformation and breakage. Time and money are saved in the research and development process by carrying out these calculations and static analyses of physical properties before prototypes are actually built.

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

    Science.gov (United States)

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

    1985-07-01

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

  10. A soft rotor concept - design, verification and potentials

    Energy Technology Data Exchange (ETDEWEB)

    Rasmussen, F.; Thirstrup Petersen, J. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    This paper contains results from development and testing of a two-bladed soft rotor for an existing 15 kW flexible wind turbine. The new concept is characterised as a free yawing down wind turbine with nacelle tilting flexibility and a two-bladed teetering rotor with three-point supported flexible blades with built-in structural couplings. The power and the loads are controlled by active stall and active coning. The concept has been developed by extensive application of aero-elastic predictions, numerical optimisation and stability analysis in order to obtain optimal aero-elastic response and minimal loads. The flexible blades and the principle of active coning allow the blades to deflect with the wind to such an extent that the loads are reduced to between 25 and 50% of the loads for a similar rigid rotor. All conceptual design principles have been focused on application to large MW turbines, and aero-elastic predictions for an upscale 1 MW version show that this would have approximately identical characteristisc, without being particularly optimised for the actual size. (au)

  11. Static and dynamic analysis of 1 220 mm steel last stage blade for steam turbine

    Directory of Open Access Journals (Sweden)

    Kubín Z.

    2009-06-01

    Full Text Available The 3 000 rpm 1 220 mm blade for a steam turbine was developed with application of new design features. The last stage moving blade is designed with an integral cover, a mid-span tie-boss connection and a fir-tree dovetail. With this configuration the blades are continuously coupled by the blade untwist due to the centrifugal force when the blades rotate at high speed, so that vibration control and increased structural damping are provided. Blade was tuned in order to eigen-frequencies were safely far from possible excitation. Because of connection members, the number of the resonant vibration modes can be reduced by virtue of the vibration characteristics of the circumferentially continuous blades. The last stage airfoil was optimalized from view of minimalization of its centrifugal force. In order to develop the 3 000 rpm 1 220 mm blade, the advanced analysis methods to predict dynamics behavior of the bladed structure were applied. Coupled rotor-blade analysis was also aim of the attention. To validate calculated results the verification measurement such as rotational vibration tests was carried out in the high-speed test rig. Relation of the friction damping of the bladed structure on amount of excitation level was also monitored and evaluated.

  12. Fundamentals for remote structural health monitoring of wind turbine blades - a preproject. Annex A. Cost-benefit for embedded sensors in large wind turbine blades

    DEFF Research Database (Denmark)

    Hansen, L.G.; Lading, Lars

    2002-01-01

    This report contains the results of a cost-benefit analysis for the use of embed-ded sensors for damage detection in large wind turbine blades - structural health monitoring - (in connection with remote surveillance) of large wind turbine placedoff-shore. The total operating costs of a three......-bladed 2MW turbine placed offshore either without sensors or with sensors are compared. The price of a structural health monitoring system of a price of 100 000 DKK (per tur-bine) results in a break-eventime of about 3 years. For a price of 300 000 DKK the break-even time is about 8 years. However...

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

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Bitsche, Robert

    2015-01-01

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

  14. Structural transformations and temperature state of rotating blades of E1893 alloy under operation

    Energy Technology Data Exchange (ETDEWEB)

    Pigrova, G.D.; Rybnikov, A.I.; Kryukov, I.I. [Polzunov Central Boiler and Turbine Institute, St. Petersburg (Russian Federation)

    1998-12-31

    The composition and quantity of different phase component of EI893 alloy after long term operation as base metal for rotating blades of gas turbines GT-6, GTN-9, GTK-10 and GT-100 types were studied. The obtained date were analysed with regard to the chemical composition of alloys and of initial condition of heat treatment. Data of metal phase analysis owned alter operation can provide the basis for evaluation of tempera field of rotating blades in the course of operation since structural condition of phase components and redistribution of alloying elements are being specified by temperature and in-service time. (orig.)

  15. 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.

  16. 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.

  17. Structural modelling of composite beams with application to wind turbine rotor blades

    DEFF Research Database (Denmark)

    Couturier, Philippe

    represented within the elements. A post processing scheme is also presented to recover inter laminar stresses via equilibrium equations of 3D elasticity derived in the laminate coordinate system.In the final part of the thesis a flexible method for analysing two types of instabilities associated with bending...... of thin-walled prismatic beams is presented. First, the flattening instability from the Brazier effect is modelled by representing the cross-section by two-dimensional non-linear co-rotating beam elements with imposed in-plane loads proportional to the curvature. Second, the bifurcation instability from...... distributions.In the second part a formulation developed for analysis of the stiffness properties of general cross-sections with arbitrary geometry and material distribution is presented.The full six by six cross-section stiffness matrix is obtained by imposing simple deformation modes on a single layer of 3D...

  18. 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....

  19. Wind rotor with vertical axis. Vindrotor med vertikal axel

    Energy Technology Data Exchange (ETDEWEB)

    Colling, J.; Sjoenell, B.

    1987-06-15

    This rotor is of dual type i.e. a paddle wheel shaped rotor close to the vertical axis and a second rotor consisting of vertical blades with wing profile and attached to radial spokes which are fixed to the axis together with the paddle wheel rotor. (L.F.).

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  1. 9th IFToMM International Conference on Rotor Dynamics

    CERN Document Server

    2015-01-01

    This book presents the proceedings of the 9th IFToMM International Conference on Rotor Dynamics. This conference is a premier global event that brings together specialists from the university and industry sectors worldwide in order to promote the exchange of knowledge, ideas, and information on the latest developments and applied technologies in the dynamics of rotating machinery. The coverage is wide ranging, including, for example, new ideas and trends in various aspects of bearing technologies, issues in the analysis of blade dynamic behavior,  condition monitoring of different rotating machines, vibration control, electromechanical and fluid-structure interactions in rotating machinery, rotor dynamics of micro, nano, and cryogenic machines, and applications of rotor dynamics in transportation engineering. Since its inception 32 years ago, the IFToMM International Conference on Rotor Dynamics has become an irreplaceable point of reference for those working in the field, and this book reflects the high qua...

  2. 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

  3. Optimum design configuration of Savonius rotor through wind tunnel experiments

    Energy Technology Data Exchange (ETDEWEB)

    Saha, U.K.; Thotla, S. [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039 (India); Maity, D. [Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039 (India)

    2008-08-15

    Wind tunnel tests were conducted to assess the aerodynamic performance of single-, two- and three-stage Savonius rotor systems. Both semicircular and twisted blades have been used in either case. A family of rotor systems has been manufactured with identical stage aspect ratio keeping the identical projected area of each rotor. Experiments were carried out to optimize the different parameters like number of stages, number of blades (two and three) and geometry of the blade (semicircular and twisted). A further attempt was made to investigate the performance of two-stage rotor system by inserting valves on the concave side of blade. (author)

  4. 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.

  5. 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...

  6. 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...

  7. Structure simulation in unidirectionally solidified turbine blade by dendrite envelope tracking model(Ⅰ): numerical modeling

    Institute of Scientific and Technical Information of China (English)

    WANG Tong-min; I. Ohnaka; H.Yasuda; SU Yan-qing; GUO Jing-jie

    2006-01-01

    A 3D dendrite envelope tracking model was developed for estimating the solidification structure of unidirectionally solidified turbine blade. The normal vector of dendrite envelope was estimated by the gradient of dendrite volume fraction, and growth velocity of the dendrite envelope (dendrite tips) was calculated with considering the anisotropy of grain growth. The solute redistribution at dendrite envelope was calculated by introducing an effective solute partition coefficient(ke). Simulation results show that the solute-build-up due to the rejection at envelope affects grain competition and consequently the solidification structure. The lower value of ke leads to more waved dendrite growth front and higher solute rejection. The model was applied to predict the structure of turbine-blade-shape samples showing good ability to reproduce the columnar and single grain structures.

  8. STRUCTURAL SYNTHESIS OF A STABILIZING ROBUST CONTROLLER OF THE ROTOR FLUX LINKAGE

    Directory of Open Access Journals (Sweden)

    N. J. Khlopenko

    2017-03-01

    Full Text Available Purpose. The aim is to structural synthesis of robust stabilizing control of the rotor flux vector control system of induction motor. Methodology. Synthesis controller structure was carried out in two stages. The first stage constructed a mathematical model of the channel of the rotor flux with parametric uncertainty and calculated transfer function of H∞-suboptimal controller by method of the mixed sensitivity. The second stage was carried out the expansion of the transfer function of the continued fraction for the Euclidean algorithm. This fraction was used to construct the controller structural scheme. Results. Computer modeling of the transfer function of H∞-suboptimal controller. Achieved decomposition found the transfer function of the continued fraction. The flow diagram of suboptimal H∞-controller with a proportional and integrating links and a few summers. The curves of transient rotor flux linkage in packages Robust Control Toolbox and Simulink. They coincide in the steady state, but differ among themselves in the transition. Originality. We developed the method of structural synthesis of robust stabilizing controller of the flux linkage rotor, H∞-suboptimal structural scheme of which is presented in the form of simple compounds integrating and proportional elements of the same order as the controller with the strictly correct transfer function, and takes into account the parametric uncertainty of control object. The results of the simulation of transient processes in a variety of packages MATLAB applications confirms the adequacy and small sensitivity of the system to parametric perturbation. Practical value. The resulting structure of the controller makes it possible to carry out the modernization of electric control systems, in use, with minimal financial costs.

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

    OpenAIRE

    Shires, A.; Kourkoulis, V

    2013-01-01

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

  10. Minimum weight design of rotorcraft blades with multiple frequency and stress constraints

    Science.gov (United States)

    Chattopadhyay, Aditi; Walsh, Joanne L.

    1988-01-01

    Minimum weight designs of helicopter rotor blades with constraints on multiple coupled flap-lag natural frequencies are studied. Constraints are imposed on the minimum value of the blade autorotational inertia to ensure sufficient rotary inertia to autorotate in case of engine failure and on stresses to guard against structural failure due to blade centrifugal forces. Design variables include blade taper ratio, dimensions of the box beam located inside the airfoil and magnitudes of nonstructural weights. The program CAMRAD is used for the blade modal analysis; the program CONMIN is used for the optimization. A linear approximation involving Taylor series expansion is used to reduce the analysis effort. The procedure contains a sensitivity analysis consisting of analytical derivatives for objective function and constraints on autorotational inertia and stresses. Central finite difference derivatives are used for frequency constraints. Optimal designs are obtained for both rectangular and tapered blades. Using this method, it is possible to design a rotor blade with reduced weight, when compared to a baseline blade, while satisfying all the imposed design requirements.

  11. Composite Structural Analysis of Flat-Back Shaped Blade for Multi-MW Class Wind Turbine

    Science.gov (United States)

    Kim, Soo-Hyun; Bang, Hyung-Joon; Shin, Hyung-Ki; Jang, Moon-Seok

    2014-06-01

    This paper provides an overview of failure mode estimation based on 3D structural finite element (FE) analysis of the flat-back shaped wind turbine blade. Buckling stability, fiber failure (FF), and inter-fiber failure (IFF) analyses were performed to account for delamination or matrix failure of composite materials and to predict the realistic behavior of the entire blade region. Puck's fracture criteria were used for IFF evaluation. Blade design loads applicable to multi-megawatt (MW) wind turbine systems were calculated according to the Germanischer Lloyd (GL) guideline and the International Electrotechnical Commission (IEC) 61400-1 standard, under Class IIA wind conditions. After the post-processing of final load results, a number of principal load cases were selected and converted into applied forces at the each section along the blade's radius of the FE model. Nonlinear static analyses were performed for laminate failure, FF, and IFF check. For buckling stability, linear eigenvalue analysis was performed. As a result, we were able to estimate the failure mode and locate the major weak point.

  12. Rotor/body aerodynamic interactions

    Science.gov (United States)

    Betzina, M. D.; Smith, C. A.; Shinoda, P.

    1985-01-01

    A wind tunnel investigation was conducted in which independent, steady state aerodynamic forces and moments were measured on a 2.24 m diam. two bladed helicopter rotor and on several different bodies. The mutual interaction effects for variations in velocity, thrust, tip-path-plane angle of attack, body angle of attack, rotor/body position, and body geometry were determined. The results show that the body longitudinal aerodynamic characteristics are significantly affected by the presence of a rotor and hub, and that the hub interference may be a major part of such interaction. The effects of the body on the rotor performance are presented.

  13. Structure defect prediction of single crystal turbine blade by dendrite envelope tracking model

    Institute of Scientific and Technical Information of China (English)

    WANG Tong-min; Itsuo OHNAKA; Hideyuki YASUDA; SU Yan-qing; GUO Jing-jie

    2006-01-01

    The structure defects such as stray grains during unidirectional solidification can severely reduce the performance of single crystal turbine blades. A dendrite envelope tracking model is developed for predicting the structure defects of unidirectional solidification turbine blade. The normal vector of dendrite envelope is estimated by the gradient of dendrite volume fraction,and the growth velocity of the dendrite envelope (dendrite tips) is calculated with considering the anisotropy of grain growth. The solute redistribution at dendrite envelope is calculated by introducing an effective solute partition coefficient. Simulation tests show that the solute-build-up due to the rejection at envelope greatly affects grain competition and consequently solidification structure. The model is applied to predict the structure defects (e.g. stray grain) of single crystal turbine blade during unidirectional solidification. The results show that the developed model is reliable and has the following abilities: reproduce the growth competition among the different-preferential-direction grains:predict the stray grain formation:simulate the structure evolution (single crystal or dendrite grains).

  14. The performance analysis and calculation for variable frequency speed control motors with the rotor structure optimized

    Institute of Scientific and Technical Information of China (English)

    CAO Jun-ci; LI Wei-li

    2005-01-01

    In the paper, the method to optimize the rotor structure in variable frequency speed control motors is introduced. The saturation and the skin effect are considered and 2D no-load and load electromagnetic field is calculated in finite elements for a variable frequency speed control motor before and after optimization. Finally,no-load current and operation performance before and after optimization are obtained and the two results are contrasted.

  15. Internal structural optimization of hollow fan blade based on sequential quadratic programming algorithm

    Institute of Scientific and Technical Information of China (English)

    YANG Jian-qiu; WANG Yan-rong

    2011-01-01

    Several structural design parameters for the description of the geometric features of a hollow fan blade were determined. A structural design optimization model of a hollow fan blade which based on the strength constraint and minimum mass was established based on the finite element method through these parameters. Then, the sequential quadratic programming algorithm was employed to search the optimal solutions. Several groups of value for initial design variables were chosen, for the purpose of not only finding much more local optimal results but also analyzing which discipline that the variables according to could be benefit for the convergence and robustness. Response surface method and Monte Carlo simulations were used to analyze whether the objective function and constraint function are sensitive to the variation of variables or not. Then the robust results could be found among a group of different local optimal solutions.

  16. Effect of ETA treatment on corrosion fatigue in rotors and blades and stress corrosion cracking in 3.5 NiCrMoV steel low-pressure turbine discs

    Energy Technology Data Exchange (ETDEWEB)

    Hitomi, Itoh [Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center (Japan); Takashi, Momoo [Mitsubishi Heavy Industries, Ltd., Takasago Machinery Works (Japan); Takayuki, Shiomi [Kansai Electric Power Co., Inc., Osaka (Japan)

    2001-07-01

    In recent years, to increase the reliability and reduce the amount of feed water iron to prevent of fouling of steam generator tubes, ethanolamine (ETA) treatment has been adopted into the secondary system. In this investigation, the authors verified that ethanolamine treatment does not adversely affect the susceptibility of either stress corrosion cracking (SCC) in the turbine discs that are the principal units in the secondary system or corrosion fatigue (CF) in rotors and blades. In the first stage, a laboratory investigation was made of (1) SCC initiation and propagation in 3,5 NiCrMoV steel and (2) CF in 3,5 NiCrMoV steel and blade steels, in both cases using deaerated water to which had been added ethanolamine with few organic acids that is 10 times the estimated concentration. It was confirmed that the ethanolamine treatment had almost no effect. In the second stage, test pieces (removed from the disc steel inserted into the turbine extraction chamber before the ethanolamine treatment was started) were used to observe the initiation and propagation of SCC. Even after long-term observation, ethanolamine treatment into the secondary system was found to have almost no effect on the susceptibility of SCC in discs. (author)

  17. Design and analysis of small wind turbine blades with wakes similar to those of industrial scale turbines

    Science.gov (United States)

    Hassanzadeh, Arash; Naughton, Jonathan

    2016-11-01

    A new design approach has been developed for wind turbine blades to be used in wind tunnel experiments that study wind turbine wakes. The approach allows wakes of small scale (2 m diameter) wind turbine rotors to simulate the important physics of wakes generated by a "parent" industrial scale wind turbine rotor despite the difference in size. The design approach forces the normalized normal and tangential force distributions of the small scale wind turbine blades to match those of the "parent" industrial scale wind turbine blades. The wake arises from the interaction between the flow and the blade, which imparts a momentum deficit and rotation to the flow due to the forces created by the blade on the flow. In addition, the wake dynamics and stability are affected by the load distribution across the blade. Thus, it is expected that matching normalized force distributions should result in similar wake structure. To independently assess the blades designed using this approach, the "parent" industrial scale and small scale wind turbine rotors are modeled using a free vortex wake method to study the generation and evolution of the two wakes. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award # DE-SC0012671.

  18. 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.

  19. A 100-kW wind turbine blade dynamics analysis, weight-balance, and structural test results

    Science.gov (United States)

    Anderson, W. D.

    1975-01-01

    The results of dynamic analyses, weight and balance tests, static stiffness tests, and structural vibration tests on the 60-foot-long metal blades for the ERDA-NASA 100-kW wind turbine are presented. The metal blades are shown to be free from structural or dynamic resonance at the wind turbine design speed. Aeroelastic instabilities are unlikely to occur within the normal operating range of the wind turbine.

  20. A comprehensive vibration analysis of a coupled rotor/fuselage system

    Science.gov (United States)

    Yeo, Hyeonsoo

    A comprehensive vibration analysis of a coupled rotor/fuselage system for a two-bladed teetering rotor using finite element methods in space and time is developed which incorporates consistent rotor/fuselage structural, aerodynamic, and inertial couplings and a modern free wake model. A coordinate system is developed to take into account a teetering rotor's unique characteristics, such as teetering motion and undersling. Coupled nonlinear periodic blade and fuselage equations are transformed to the modal space in the fixed frame and solved simultaneously. The elastic line and detailed 3-D NASTRAN finite element models of the AH-1G helicopter airframe from the DAMVIBS program are integrated into the elastic rotor finite element model. Analytical predictions of rotor control angles, blade loads, hub forces, and vibration are compared with AH-1G Operation Load Survey flight test data. The blade loads predicted by present analysis show generally fair agreement with the flight test data, especially blade chord bending moment estimation shows good agreement. Calculated 2/rev vertical vibration levels at pilot seat show good correlation with the flight test data both in magnitude and phase, but 4/rev vibration levels show fair correlation only in magnitude. Lateral vibration results show more disagreement than vertical vibration results. Pylon flexibility effect is essential in the two-bladed teetering rotor vibration analysis. The pylon flexibility increases the first lag frequency by about 14%, and decreases 2/rev longitudinal and lateral hub forces by more than half. Rotor/fuselage coupling reduces 2/rev vertical and lateral vibration levels by 60% to 70% and has a small effect on 4/rev vibration levels. Modeling of difficult components (secondary structures, doors/panels, etc) is essential in predicting airframe natural frequencies. Refined aerodynamics such as free wake and unsteady aerodynamics have an important role in the prediction of vibration. For example, free

  1. 14 CFR 29.549 - Fuselage and rotor pylon structures.

    Science.gov (United States)

    2010-01-01

    ... flight conditions, must be considered. (c) Each engine mount and adjacent fuselage structure must be designed to withstand the loads occurring under accelerated flight and landing conditions, including engine torque. (d) (e) If approval for the use of 21/2-minute OEI power is requested, each engine mount...

  2. Rotor-rotor interaction for counter-rotating fans. Part 1: Three-dimensional flowfield measurements

    Science.gov (United States)

    Shin, Hyoun-Woo; Whitfield, Charlotte E.; Wisler, David C.

    1994-11-01

    The rotor wake/vortex flowfield generated in a scale model simulator of General Electric's counter-rotating unducted fan (UDF) engine was investigated using three-dimensional hot-wire anemometry. The purpose was to obtain a set of benchmark experimental aerodynamic data defining the rotor wake and vortex structure, particularly in the tip region, and to relate this observed flow structure to its acoustic signature. The tests were conducted in a large, freejet anechoic chamber. Measurements of the three components of velocity were made at axial stations upstream and downstream of each rotor for conditions that simulate takeoff, cutback, and approach power. Two different forward blade designs were evaluated. The tip vortices, the axial velocity defect in the vortex core, and differences in the interaction of the wakes and vortices generated by the forward and aft rotor are used to explain differences in noise generated by the two different rotor designs. Part 1 presents the three-dimensional flowfield measurements. Part 2 (aeroacoustic prediction and analysis), which will be presented later, will give an acoustic prediction using the measured data.

  3. Full-scale S-76 rotor performance and loads at low speeds in the NASA Ames 80- by 120-Foot Wind Tunnel. Vol. 1

    Science.gov (United States)

    Shinoda, Patrick M.

    1996-01-01

    A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. Rotor performance and loads data were obtained over a wide range of rotor shaft angles-of-attack and thrust conditions at tunnel speeds ranging from 0 to 100 kt. The primary objectives of this test were (1) to acquire forward flight rotor performance and loads data for comparison with analytical results; (2) to acquire S-76 forward flight rotor performance data in the 80- by 120-Foot Wind Tunnel to compare with existing full-scale 40- by 80-Foot Wind Tunnel test data that were acquired in 1977; (3) to evaluate the acoustic capability of the 80- by 120- Foot Wind Tunnel for acquiring blade vortex interaction (BVI) noise in the low speed range and compare BVI noise with in-flight test data; and (4) to evaluate the capability of the 80- by 120-Foot Wind Tunnel test section as a hover facility. The secondary objectives were (1) to evaluate rotor inflow and wake effects (variations in tunnel speed, shaft angle, and thrust condition) on wind tunnel test section wall and floor pressures; (2) to establish the criteria for the definition of flow breakdown (condition where wall corrections are no longer valid) for this size rotor and wind tunnel cross-sectional area; and (3) to evaluate the wide-field shadowgraph technique for visualizing full-scale rotor wakes. This data base of rotor performance and loads can be used for analytical and experimental comparison studies for full-scale, four-bladed, fully articulated rotor systems. Rotor performance and structural loads data are presented in this report.

  4. Fundamentals for remote structural health monitoring of wind turbine blades - a pre-project. Annex A - Cost-benefit for embedded sensors in large wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Gottlieb Hansen, Lars; Lading, L.

    2002-05-01

    This report contains the results of a cost-benefit analysis for the use of embedded sensors for damage detection in large wind turbine blades - structural health monitoring - (in connection with remote surveillance) of large wind turbine placed off-shore. The total operating costs of a three-bladed 2MW turbine placed offshore either without sensors or with sensors are compared. The price of a structural health monitoring system of a price of 100,000 DKK (per turbine) results in a break-even time of about 3 years. For a price of 300,000 DKK the break-even time is about 8 years. However, the cost/benefit analysis has large uncertainties. (au)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-15

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

  6. Wind Turbine Rotors with Active Vibration Control

    DEFF Research Database (Denmark)

    Svendsen, Martin Nymann

    are assumed to be proportional to the relative inflow angle, which also gives a linear form with equivalent stiffness and damping terms. Geometric stiffness effects including the important stiffening from tensile axial stresses in equilibrium with centrifugal forces are included via an initial stress......This thesis presents a framework for structural modeling, analysis and active vibration damping of rotating wind turbine blades and rotors. A structural rotor model is developed in terms of finite beam elements in a rotating frame of reference. The element comprises a representation of general...... formulation. The element provides an accurate representation of the eigenfrequencies and whirling modes of the gyroscopic system, and identifies lightly damped edge-wise modes. By adoption of a method for active, collocated resonant vibration of multi-degree-of-freedom systems it is demonstrated...

  7. Measurement of Vortex Strength and Core Diameter in the Wake of a Hovering Rotor

    Science.gov (United States)

    Wadcock, Alan J.

    1997-01-01

    Detailed hot wire measurements have been acquired in the tip vortex of a three-bladed model tilt rotor in hover. Testing was conducted at a rotor tip speed of 752 ft/sec, a Reynolds number (based on blade tip chord) of 1.77 x 10(exp 6), for thrust coefficients up to 0.0160. A figure shows the hot wire mounted above the inverted rotor at the Outside Aerodynamic Rotor Facility (OARF) at NASA Ames Research Center. Strobed shadowgraph flow visualization was used to define the vortex trajectory as an aid in hot wire positioning. Considerable variations in tip vortex structure with time were observed, even from the same blade, under essentially uniform test conditions. The only velocity signatures analyzed were those corresponding to passage of the probe directly through the center of the vortex. These time histories were ensemble averaged after compensating for jitter in the vortex arrival time at the probe, thereby retaining the core structure with minimal smearing. An example of a mean velocity signature, after ensemble averaging, is shown. The mean velocity signature was analyzed under the assumption of constant (unknown) translation speed of the vortex filament past the fixed probe. The translation speed of the vortex is deduced and the vortex strength and core diameter inferred. The results were highly unexpected. The indicated vortex strength is seen to decrease rapidly after first blade passage. In addition, the core radius is seen to decrease with increasing wake age, not increase as might be expected from simple diffusion.

  8. 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.

  9. A coupling VWM/CFD/CSD method for rotor airload prediction

    Directory of Open Access Journals (Sweden)

    Yongjie Shi

    2017-02-01

    Full Text Available A coupling fluid-structure method with a combination of viscous wake model (VWM, computational fluid dynamics (CFD and comprehensive structural dynamics (CSD modules is developed in this paper for rotor unsteady airload prediction. The hybrid VWM/CFD solver is employed to model the nonlinear aerodynamic phenomena and complicated rotor wake dynamics; the moderate deflection beam theory is implemented to predict the blade structural deformation; the loose coupling strategy based on the ‘delt method’ is used to couple the fluid and structure solvers. Several cases of Helishape 7A rotor are performed first to investigate the effect of elastic deformation on airloads. Then, two challenging forward flight conditions of UH-60A helicopter rotor are investigated, and the simulated results of wake geometry, chordwise pressure distribution and sectional normal force show excellent agreement with available test data; a comparison with traditional CFD/CSD method is also presented to illustrate the efficiency of the developed method.

  10. The performance of rotary power tiller using prototype rotary blades in dry-land field

    Directory of Open Access Journals (Sweden)

    Sirisak Chertkiattipol

    2008-11-01

    Full Text Available The effect of shape of prototype rotary blades on the performance of rotary power tiller was investigated in this study. Three sets of rotors, i.e. 14-blade rotor of the Japanese C-shape blade (4.5 cm tilling width of one blade; T1, 14-blade rotor of the prototype rotary blade no. 1 (4.5 cm tilling width of one blade; T2, and 10-blade rotor of the prototype rotary blade no. 2 (6.5 cm tilling width of one blade; T3 were used. The tests were conducted in a dry-land field of clay loam with soil moisture content of 16.04 % (d.b. and dry bulk density of 1.51 g/cm3 at different rotational speeds of 300, 350 and 400 rpm at one and two tilling passes. For all rotors, experimental results showed that the mean soil clod diameter decreased and soil inversion increased with increasing rotational speed of the rotor. The mean soil clod diameter decreased at pass 2. Soil inversion during pass 2 was higher than pass 1. However, the three sets of rotors showed no significant difference on mean soil clod diameter and soil inversion. The shape of blade prototype rotary blade no. 1 and the decreasing number of prototype rotary blade no. 2 did not affect the tillage performance as compared with the Japanese C-shaped blade.

  11. Stochastic Modeling of Lift and Drag Dynamics to Obtain Aerodynamic Forces with Local Dynamics on Rotor Blade under Unsteady Wind Inflow

    Directory of Open Access Journals (Sweden)

    Muhammad Ramzan Luhur

    2014-01-01

    Full Text Available This contribution provides the development of a stochastic lift and drag model for an airfoil FX 79-W-151A under unsteady wind inflow based on wind tunnel measurements. Here we present the integration of the stochastic model into a well-known standard BEM (Blade Element Momentum model to obtain the corresponding aerodynamic forces on a rotating blade element. The stochastic model is integrated as an alternative to static tabulated data used by classical BEM. The results show that in comparison to classical BEM, the BEM with stochastic approach additionally reflects the local force dynamics and therefore provides more information on aerodynamic forces that can be used by wind turbine simulation codes

  12. Fundamentals for remote structural health monitoring of wind turbine blades - a preproject. Annex C. Fibre transducer for damage detection in adhesive layers of wind turbine blades

    DEFF Research Database (Denmark)

    Sendrup, P.

    2002-01-01

    displacement transducer for detection of damage in adhesive layers of wind turbine blades. It was chosen to base the transducer on the fibre optic micro-bend principle. The report contains the result of measurementsand optical simulations of light transmittance through optical fibres with micro......-bends and a suggestion for a micro-bend transducer design specifically suitable for detection of damage in adhesive layers between larger composite structures, as the shellsin a wind turbine blade. Such a damage will cause the joined parts to move slightly relative to each other, and the transducer is designed to change......This report (annex to the summary report "Grundlag for fjernovervågning af vindmøllevingers tilstand (Fase I: Forprojekt)", of a project partly supported by PSO-funding through Elkraft System, contract no. Bro-91.055, FU nr. 1102) describes the work carriedout to design and test a fibre optic...

  13. Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations, Phase 1

    Science.gov (United States)

    Hohenemser, K. H.; Gaonkar, G. H.

    1967-01-01

    A number of lifting rotor conditions with random inputs are discussed. The present state of random process theory, applicable to lifting rotor problems is sketched. Possible theories of random blade flapping and random blade flap-bending are outlined and their limitations discussed. A plan for preliminary experiments to study random flapping motions of a see-saw rotor is developed.

  14. Wind tunnel tests on slow-running vertical-axis wind-rotors

    Science.gov (United States)

    Sivasegaram, S.

    1981-09-01

    This paper summarizes the results of investigations on the Savonius-type, slow-running, vertical-axis wind-rotors as well as on rotor designs on different subclasses under comparable design and test conditions. It is seen that the performance of the conventional Savonius rotor could be considerably improved upon and the best results are achieved by using two-bladed rotors with a more sophisticated sectional profile than in the conventional design. Rotors with several blades, although capable of considerably higher performance than the Savonius rotor, do not appear to be as good as those with two blades and improved sectional geometry.

  15. Experimental study on the aerodynamic performance of a Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, Nobuyuki; Gotoh, Futoshi (Gunma Univ., Kiryu (Japan). Dept. of Mechanical Engineering)

    1994-08-01

    The aerodynamic performance of a Savonius rotor has been studied by measuring the pressure distributions on the blade surfaces at various rotor angles and tip-speed ratios. It is found that the pressure distributions on the rotating rotor differ remarkably from those on the still rotor especially on the convex side of the advancing blade, where a low pressure region is formed by the moving wall effect of the blade. The torque and power performances, evaluated by integrating the pressure, are in close agreement with those by the direct torque measurement. The drag and side force performance is also studied.

  16. System Identification of Mistuned Bladed Disks from Traveling Wave Response Measurements

    Science.gov (United States)

    Feiner, D. M.; Griffin, J. H.; Jones, K. W.; Kenyon, J. A.; Mehmed, O.; Kurkov, A. P.

    2003-01-01

    A new approach to modal analysis is presented. By applying this technique to bladed disk system identification methods, one can determine the mistuning in a rotor based on its response to a traveling wave excitation. This allows system identification to be performed under rotating conditions, and thus expands the applicability of existing mistuning identification techniques from integrally bladed rotors to conventional bladed disks.

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

    Science.gov (United States)

    Adams, Zachary Howard

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

  18. Large Wind Turbine Rotor Design using an Aero-Elastic / Free-Wake Panel Coupling Code

    Science.gov (United States)

    Sessarego, Matias; Ramos-García, Néstor; Shen, Wen Zhong; Nørkær Sørensen, Jens

    2016-09-01

    Despite the advances in computing resources in the recent years, the majority of large wind-turbine rotor design problems still rely on aero-elastic codes that use blade element momentum (BEM) approaches to model the rotor aerodynamics. The present work describes an approach to wind-turbine rotor design by incorporating a higher-fidelity free-wake panel aero-elastic coupling code called MIRAS-FLEX. The optimization procedure includes a series of design load cases and a simple structural design code. Due to the heavy MIRAS-FLEX computations, a surrogate-modeling approach is applied to mitigate the overall computational cost of the optimization. Improvements in cost of energy, annual energy production, maximum flap-wise root bending moment, and blade mass were obtained for the NREL 5MW baseline wind turbine.

  19. Impact of Aerodynamics and Structures Technology on Heavy Lift Tiltrotors

    Science.gov (United States)

    Acree, C. W., Jr.

    2006-01-01

    Rotor performance and aeroelastic stability are presented for a 124,000-lb Large Civil Tilt Rotor (LCTR) design. It was designed to carry 120 passengers for 1200 nm, with performance of 350 knots at 30,000 ft altitude. Design features include a low-mounted wing and hingeless rotors, with a very low cruise tip speed of 350 ft/sec. The rotor and wing design processes are described, including rotor optimization methods and wing/rotor aeroelastic stability analyses. New rotor airfoils were designed specifically for the LCTR; the resulting performance improvements are compared to current technology airfoils. Twist, taper and precone optimization are presented, along with the effects of blade flexibility on performance. A new wing airfoil was designed and a composite structure was developed to meet the wing load requirements for certification. Predictions of aeroelastic stability are presented for the optimized rotor and wing, along with summaries of the effects of rotor design parameters on stability.

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

    DEFF Research Database (Denmark)

    Kallesøe, Bjarne Skovmose

    2006-01-01

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

  1. Design of Dynamic Strain Measurement System of Rotor Blades Impacted by Bird%旋转叶片鸟撞动态应变测量系统设计

    Institute of Scientific and Technical Information of China (English)

    马坚刚; 张天宏; 孙健国

    2013-01-01

    In order to solve the difficulties of dynamic strain measurement of rotor blades impacted by bird,a method based on on-line detection and high-speed temporary storage is put forward.Through the real-time online detection,the strain data of bird impact in the whole process is collected and stored in a non-volatile SRAM.A multi-channel dynamic strain measurement system is designed mainly,including the detection and storage unit and the ground auxiliary device,which can meet the requirements of accuracy and speed,and realize the functions of on-line detection,high-speed storage and wireless data transmission.The tests indicate that the system has high accuracy and can detect the bird impact in real-time,and the speed of collection and storage is 200 kHz with 6 channels,and the test is convenient by using radio communication,which satisfies the dynamic strain measurement of rotor blades impacted by bird.%为了解决旋转叶片鸟撞时动态应变测量困难的问题,提出一种基于在线检测和高速暂存的测量方法.通过实时在线检测,将鸟撞发生时全过程的应变量采集并高速存储在非易失性存储器中.重点设计多通道动态应变测量系统,包括检测存储单元和地面辅助装置,满足精度、速率要求,实现在线检测、高速存储和无线数据传输等功能.试验表明,系统具有较高的测量精度,能实时检测到鸟撞发生,最快以6通道200 kHz的速率采集和存储,并利用无线数据传输,满足旋转叶片鸟撞动态应变测量要求.

  2. Shape Optimization of Impeller Blades for 15,000 HP Centrifugal Compressor Using Fluid Structural Interaction Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hyun Su [Sungkyunkwan University, Suwon (Korea, Republic of); Oh, Jeongsu [Daejoo Machinery Co., Daegu (Korea, Republic of); Han, Jeong Sam [Andong National University, Andong (Korea, Republic of)

    2014-06-15

    This paper discusses a one-way fluid structural interaction (FSI) analysis and shape optimization of the impeller blades for a 15,000 HP centrifugal compressor using the response surface method (RSM). Because both the aerodynamic performance and the structural safety of the impeller are affected by the shape of its blades, shape optimization is necessary using the FSI analysis, which includes a structural analysis for the induced fluid pressure and centrifugal force. The FSI analysis is performed in ANSYS Workbench: ANSYS CFX is used for the flow field and ANSYS Mechanical is used for the structural field. The response surfaces for the FSI results (efficiency, pressure ratio, maximum stress, etc.) generated based on the design of experiments (DOE) are used to find an optimal shape for the impeller blades, which provides the maximum aerodynamic performance subject to the structural safety constraints.

  3. Design of a wind turbine rotor for maximum aerodynamic efficiency

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Aagaard Madsen, Helge; Gaunaa, Mac;

    2009-01-01

    The design of a three-bladed wind turbine rotor is described, where the main focus has been highest possible mechanical power coefficient, CP, at a single operational condition. Structural, as well as off-design, issues are not considered, leading to a purely theoretical design for investigating...... and a full three-dimensional Navier-Stokes solver. Excellent agreement is obtained using the three models. Global CP reaches a value of slightly above 0.51, while global thrust coefficient CT is 0.87. The local power coefficient Cp increases to slightly above the Betz limit on the inner part of the rotor......; the local thrust coefficient Ct increases to a value above 1.1. This agrees well with the theory of de Vries, which states that including the effect of the low pressure behind the centre of the rotor stemming from the increased rotation, both Cp and Ct will increase towards the root. Towards the tip, both...

  4. New Dynamic Spin Rig Capabilities Used to Determine Rotating Blade Dynamics

    Science.gov (United States)

    Provenza, Andrew J.

    2004-01-01

    The Dynamic Spin Rig Facility at the NASA Glenn Research Center is used to determine the structural response of rotating engine components without the effects of aerodynamic loading. Recently, this rig's capabilities were enhanced through the replacement of grease-lubricated ball bearings with magnetic bearings. Magnetic bearings offer a number of advantages--the most important here being that they not only fully support the rotor system, but excite it as well. Three magnetic bearings support the rotor and provide five axes of controlled motion: an x- and y-axis translation at each of two radial bearings and a z-axis translation in the vertical or axial direction. Sinusoidal excitation (most commonly used) can be imparted on the rotor through the radial magnetic bearings in either a fixed or rotating frame of reference. This excitation is added directly to the magnetic bearing control output. Since the rotor is fully levitated, large translations and rotations of the rotor system can be achieved. Some of the capabilities of this excitation system were determined and reported. The accelerations obtained at the tip of a titanium flat plate test article versus the swept sine excitation sent to both radial bearings in phase and perpendicular to the plane containing the two blades are shown. Recent tests required the excitation of fundamental bending and torsional blade resonances at rotor speeds up to 10,000 rpm. Successful fixed synchronous rotation of the excitation signal provided the best detectable blade resonant vibrations at excitation frequencies up to 1100 Hz for the particular blades of interest. A noncontacting laser measurement system was used to collect blade-tip motions. From these data, the amplitude and frequency of the motion could be determined as well as the blade damping properties. Damping could be determined using two methods: (1) free decay and (2) curve fitting the vibration amplitude as a function of frequency in and around the resonance of

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

    Institute of Scientific and Technical Information of China (English)

    杨庆海; 黄洪雁; 韩万今

    2002-01-01

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

  6. The effect of the nonlinear velocity and history dependencies of the aerodynamic force on the dynamic response of a rotating wind turbine blade

    Science.gov (United States)

    van der Male, Pim; van Dalen, Karel N.; Metrikine, Andrei V.

    2016-11-01

    Existing models for the analysis of offshore wind turbines account for the aerodynamic action on the turbine rotor in detail, requiring a high computational price. When considering the foundation of an offshore wind turbine, however, a reduced rotor model may be sufficient. To define such a model, the significance of the nonlinear velocity and history dependency of the aerodynamic force on a rotating blade should be known. Aerodynamic interaction renders the dynamics of a rotating blade in an ambient wind field nonlinear in terms of the dependency on the wind velocity relative to the structural motion. Moreover, the development in time of the aerodynamic force does not follow the flow velocity instantaneously, implying a history dependency. In addition, both the non-uniform blade geometry and the aerodynamic interaction couple the blade motions in and out of the rotational plane. Therefore, this study presents the Euler-Bernoulli formulation of a twisted rotating blade connected to a rigid hub, excited by either instantaneous or history-dependent aerodynamic forces. On this basis, the importance of the history dependency is determined. Moreover, to assess the nonlinear contributions, both models are linearized. The structural response is computed for a stand-still and a rotating blade, based on the NREL 5-MW turbine. To this end, the model is reduced on the basis of its first three free-vibration mode shapes. Blade tip response predictions, computed from turbulent excitation, correctly account for both modal and directional couplings, and the added damping resulting from the dependency of the aerodynamic force on the structural motion. Considering the deflection of the blade tip, the history-dependent and the instantaneous force models perform equally well, providing a basis for the potential use of the instantaneous model for the rotor reduction. The linearized instantaneous model provides similar results for the rotating blade, indicating its potential

  7. MEMS inertial sensors for load monitoring of wind turbine blades

    Science.gov (United States)

    Cooperman, Aubryn M.; Martinez, Marcias J.

    2015-03-01

    Structural load monitoring of wind turbines is becoming increasingly important due increasing turbine size and offshore deployment. Rotor blades are key components that can be monitored by continuously measuring their deflection and thereby determining strain and loads on the blades. In this paper, a method is investigated for monitoring blade deformation that utilizes micro-electromechanical systems (MEMS) comprising triaxial accelerometers, magnetometers and gyroscopes. This approach is demonstrated using a cantilever beam instrumented with 5 MEMS and 4 strain gauges. The measured changes in angles obtained from the MEMS are used to determine a deformation surface which is used as an input to a finite element model in order to estimate the strain throughout the beam. The results are then verified by comparison with strain gauge measurements.

  8. Structural Testing at the NWTC Helps Improve Blade Design and Increase System Reliability; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    None

    2015-08-01

    Since 1990, the National Renewable Energy Laboratory’s (NREL's) National Wind Technology Center (NWTC) has tested more than 150 wind turbine blades. NWTC researchers can test full-scale and subcomponent articles, conduct data analyses, and provide engineering expertise on best design practices. Structural testing of wind turbine blades enables designers, manufacturers, and owners to validate designs and assess structural performance to specific load conditions. Rigorous structural testing can reveal design and manufacturing problems at an early stage of development that can lead to overall improvements in design and increase system reliability.

  9. Cyclic Control Optimization for a Smart Rotor

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Henriksen, Lars Christian

    2012-01-01

    The paper presents a method to determine cyclic control trajectories for a smart rotor undergoing periodic-deterministic load variations. The control trajectories result from a constrained optimization problem, where the cost function to minimize is given by the variation of the blade root flapwise...... bending moment within a rotor revolution. The method is applied to a rotor equipped with trailing edge flaps, and capable of individual blade pitching. Results show that the optimized cyclic control significantly alleviates the load variations from periodic disturbances; the combination of both cyclic...

  10. A prescribed wake rotor inflow and flow field prediction analysis, user's manual and technical approach

    Science.gov (United States)

    Egolf, T. A.; Landgrebe, A. J.

    1982-01-01

    A user's manual is provided which includes the technical approach for the Prescribed Wake Rotor Inflow and Flow Field Prediction Analysis. The analysis is used to provide the rotor wake induced velocities at the rotor blades for use in blade airloads and response analyses and to provide induced velocities at arbitrary field points such as at a tail surface. This analysis calculates the distribution of rotor wake induced velocities based on a prescribed wake model. Section operating conditions are prescribed from blade motion and controls determined by a separate blade response analysis. The analysis represents each blade by a segmented lifting line, and the rotor wake by discrete segmented trailing vortex filaments. Blade loading and circulation distributions are calculated based on blade element strip theory including the local induced velocity predicted by the numerical integration of the Biot-Savart Law applied to the vortex wake model.

  11. Numerical investigations on axial and radial blade rubs in turbo-machinery

    Science.gov (United States)

    Abdelrhman, Ahmed M.; Tang, Eric Sang Sung; Salman Leong, M.; Al-Qrimli, Haidar F.; Rajamohan, G.

    2017-07-01

    In the recent years, the clearance between the rotor blades and stator/casing had been getting smaller and smaller prior improving the aerodynamic efficiency of the turbomachines as demand in the engineering field. Due to the clearance reduction between the blade tip and the rotor casing and between rotor blades and stator blades, axial and radial blade rubbing could be occurred, especially at high speed resulting into complex nonlinear vibrations. The primary aim of this study is to address the blade axial rubbing phenomenon using numerical analysis of rotor system. A comparison between rubbing caused impacts of axial and radial blade rubbing and rubbing forces are also aims of this study. Tow rotor models (rotor-stator and rotor casing models) has been designed and sketched using SOILDSWORKS software. ANSYS software has been used for the simulation and the numerical analysis. The rubbing conditions were simulated at speed range of 1000rpm, 1500rpm and 2000rpm. Analysis results for axial blade rubbing showed the appearance of blade passing frequency and its multiple frequencies (lx, 2x 3x etc.) and these frequencies will more excited with increasing the rotational speed. Also, it has been observed that when the rotating speed increased, the rubbing force and the harmonics frequencies in x, y and z-direction become higher and severe. The comparison study showed that axial blade rub is more dangerous and would generate a higher vibration impacts and higher blade rubbing force than radial blade rub.

  12. 涡轮转子H形叶片叶尖间隙测量%H-Form Blade Tip Clearance Measurement in Turbine Rotor

    Institute of Scientific and Technical Information of China (English)

    陈洪敏; 韩伟; 熊兵; 郭光辉

    2012-01-01

    叶尖间隙是燃气轮机中的一个重要性能参数和安全监测参数。现代燃气轮机中采用H形凹腔冷却涡轮叶片,该叶片具有单叶片双间隙的特点。利用电容式叶尖间隙测量系统,通过改进算法,实现了H形叶片的叶尖间隙测量,并成功应用于H形叶片涡轮级性能试验。试验录取了三种不同设计间隙下的实际叶尖间隙变化数据,分析了叶尖间隙与涡轮性能之间的关系,并对试验中的转子异常运动进行了成功监测。%Tip clearance is an important parameter of performance and safety monitor in gas turbine. The H-form blade which is characterized with two tips has been used in modern gas turbines. Software that can calculate tip clearance of H-form blade was developed based on hardware of the capacitance tip clearance measure system, and had a good impression in a turbine experiment. Tip clearance data of three different designs were collected in experiments. The relationship between turbine performance and tip clearance was analyzed, and an abnormal state of turbine was monitored successfully in the experiment.

  13. Fluid-structure interaction computations for geometrically resolved rotor simulations using CFD

    DEFF Research Database (Denmark)

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

    2016-01-01

    This paper presents a newly developed high-fidelity fluid–structure interaction simulation tool for geometrically resolved rotor simulations of wind turbines. The tool consists of a partitioned coupling between the structural part of the aero-elastic solver HAWC2 and the finite volume computational...... fluid dynamics (CFD) solver EllipSys3D. The paper shows that the implemented loose coupling scheme, despite a non-conservative force transfer, maintains a sufficient numerical stability and a second-order time accuracy. The use of a strong coupling is found to be redundant. In a first test case......, the newly developed coupling between HAWC2 and EllipSys3D (HAWC2CFD) is utilized to compute the aero-elastic response of the NREL 5-MW reference wind turbine (RWT) under normal operational conditions. A comparison with the low-fidelity but state-of-the-art aero-elastic solver HAWC2 reveals a very good...

  14. Initial Aerodynamic and Acoustic Study of an Active Twist Rotor Using a Loosely Coupled CFD/CSD Method

    Science.gov (United States)

    Boyd, David D. Jr.

    2009-01-01

    Preliminary aerodynamic and performance predictions for an active twist rotor for a HART-II type of configuration are performed using a computational fluid dynamics (CFD) code, OVERFLOW2, and a computational structural dynamics (CSD) code, CAMRAD -II. These codes are loosely coupled to compute a consistent set of aerodynamics and elastic blade motions. Resultant aerodynamic and blade motion data are then used in the Ffowcs-Williams Hawkins solver, PSU-WOPWOP, to compute noise on an observer plane under the rotor. Active twist of the rotor blade is achieved in CAMRAD-II by application of a periodic torsional moment couple (of equal and opposite sign) at the blade root and tip at a specified frequency and amplitude. To provide confidence in these particular active twist predictions for which no measured data is available, the rotor system geometry and computational set up examined here are identical to that used in a previous successful Higher Harmonic Control (HHC) computational study. For a single frequency equal to three times the blade passage frequency (3P), active twist is applied across a range of control phase angles at two different amplitudes. Predicted results indicate that there are control phase angles where the maximum mid-frequency noise level and the 4P non -rotating hub vibrations can be reduced, potentially, both at the same time. However, these calculated reductions are predicted to come with a performance penalty in the form of a reduction in rotor lift-to-drag ratio due to an increase in rotor profile power.

  15. 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.

  16. Analysis of Grid-Scored Sandwich Structures of Different Curvatures and Grid Sizes For Wind Turbine Blades

    DEFF Research Database (Denmark)

    Laustsen, Steffen; Thomsen, Ole Thybo; Lund, Erik;

    2012-01-01

    The stress and strain field developed locally in-situ the core of grid-scored sandwich structures in wind turbine blades is investigated. Due to the many singularities occurring from the “tri-material corners”, a full 3D analysis of the sandwich structure in terms of the Finite Element Method...

  17. Fundamentals for remote structural health monitoring of wind turbine blades - a preproject. Annex E. Full-scale test of wind turbine blade, using sensors and NDT

    DEFF Research Database (Denmark)

    Kristensen, O.J.D.; McGugan, Malcolm; Sendrup, P.

    2002-01-01

    A 19.1 metre wind turbine blade was subjected to static tests. The purpose of the test series was to verify the abilities of different types of sensors to detect damage in wind turbine blades. Prior to each of the static test-series an artificial damagewas made on the blade. The damage made...

  18. Stator Blade Laser Window Research

    Science.gov (United States)

    Lugas, Grant A.

    2004-01-01

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

  19. Stator Blade Laser Window Research

    Science.gov (United States)

    Lugas, Grant A.

    2004-01-01

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

  20. On the torque mechanism of Savonius rotors

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, N. (Dept. of Mechanical Univ., Kiryu (Japan))

    1992-07-01

    The aerodynamic performance and the flow fields of Savonius rotors at various overlap ratios have been investigated by measuring the pressure distributions on the blades and by visualizing the flow fields in and around the rotors with and without rotation. Experiments have been performed on four rotors having two semicircular blades but with different overlap ratios ranging 0 to 0.5. The static torque performance is improved by increasing the overlap ratio especially on the returning blade, which is due to the pressure recovery effect by the flow through the overlap. On the other hand, the torque and the power performance of the rotating rotor reaches a maximum at an overlap of 0.15. This effect is largely created by the Coanda-like flow on the convex side of the advancing blade, which is strengthened by the flow through the overlap at this small overlap ratio. However, this phenomena is weakened as the overlap ratio is further increased, suggesting a deteriorated performance of the rotor. Observations of the flow inside the rotor indicate an increased recirculation region at such large overlap ratios, which also suggests a reduced aerodynamic efficiency for rotors with large overlap. 11 figs., 16 refs.

  1. Terahertz ISAR and x-ray imaging of wind turbine blade structures

    Science.gov (United States)

    Martin, Robert; Baird, Christopher S.; Giles, Robert H.; Niezrecki, Christopher

    2016-04-01

    During the manufacture of wind turbine blades, internal defects can form which negatively affect their structural integrity and may lead to premature failure. The purpose of this research was to conduct preliminary testing of nondestructive evaluation techniques that have the potential to scale up to larger areas. The techniques investigated were: Terahertz frequency fully-polarimetric inverse synthetic aperture radar (ISAR), and x-ray imaging. The terahertz ISAR technique employed standard polarimetric radar cross-section processing, and additionally applied an optimized polarimetry transformation known as the Euler transformation. Also, image back-rotation and compositing algorithms were used to combine multiple ISAR images into a single image to aid in defect detection. ISAR data were collected using a frequency modulated continuous wave 100 GHz radar system. The x-ray technique utilized a commercial airport cargo x-ray scanner. Multiple fiberglass samples with defects representative of manufacturing wind turbine blade defects were investigated using each of the techniques. Out-of-plane defects and resin dry patches were the primary defects of interest in these samples. Images were created of each sample using each of the techniques. Comparing these images with defect diagrams of the samples indicated that these techniques could effectively indicate the presence of certain defects.

  2. Structural Optimization Design of Horizontal-Axis Wind Turbine Blades Using a Particle Swarm Optimization Algorithm and Finite Element Method

    Directory of Open Access Journals (Sweden)

    Pan Pan

    2012-11-01

    Full Text Available This paper presents an optimization method for the structural design of horizontal-axis wind turbine (HAWT blades based on the particle swarm optimization algorithm (PSO combined with the finite element method (FEM. The main goal is to create an optimization tool and to demonstrate the potential improvements that could be brought to the structural design of HAWT blades. A multi-criteria constrained optimization design model pursued with respect to minimum mass of the blade is developed. The number and the location of layers in the spar cap and the positions of the shear webs are employed as the design variables, while the strain limit, blade/tower clearance limit and vibration limit are taken into account as the constraint conditions. The optimization of the design of a commercial 1.5 MW HAWT blade is carried out by combining the above method and design model under ultimate (extreme flap-wise load conditions. The optimization results are described and compared with the original design. It shows that the method used in this study is efficient and produces improved designs.

  3. Reliability Analysis of a Composite Blade Structure Using the Model Correction Factor Method

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimiroy; Friis-Hansen, Peter; Berggreen, Christian

    2010-01-01

    This paper presents a reliability analysis of a composite blade profile. The so-called Model Correction Factor technique is applied as an effective alternate approach to the response surface technique. The structural reliability is determined by use of a simplified idealised analytical model which...... in a probabilistic sense is model corrected so that it, close to the design point, represents the same structural behaviour as a realistic FE model. This approach leads to considerable improvement of computational efficiency over classical response surface methods, because the numerically “cheap” idealistic model...... is used as the response surface, while the time-consuming detailed model is called only a few times until the simplified model is calibrated to the detailed model....

  4. Design and performance prediction of swashplateless helicopter rotors with trailing edge flaps and tabs

    Science.gov (United States)

    Falls, Jaye

    This work studies the design of trailing edge controls for swashplateless helicopter primary control, and examines the impact of those controls on the performance of the rotor. The objective is to develop a comprehensive aeroelastic analysis for swashplateless rotors in steady level flight. The two key issues to be solved for this swashplateless control concept are actuation of the trailing edge controls and evaluating the performance of the swashplateless rotor compared to conventionally controlled helicopters. Solving the first requires simultaneous minimization of trailing flap control angles and hinge moments to reduce actuation power. The second issue requires not only the accurate assessment of swashplateless rotor power, but also similar or improved performance compared to conventional rotors. The analysis consists of two major parts, the structural model and the aerodynamic model. The inertial contributions of the trailing edge flap and tab are derived and added to the system equations in the structural model. Two different aerodynamic models are used in the analysis, a quasi-steady thin airfoil theory that includes arbitrary hinge positions for the flap and the tab, and an unsteady lifting line model with airfoil table lookup based on wind tunnel test data and computational fluid dynamics simulation. The design aspect of the problem is investigated through parametric studies of the trailing edge flap and tab for a Kaman-type conceptual rotor and a UH-60A swashplateless variant. The UH-60A model is not changed except for the addition of a trailing edge flap to the rotor blade, and the reduction of pitch link stiffness to imitate a soft root spring. Study of the uncoupled blade response identifies torsional stiffness and flap hinge stiffness as important design features of the swashplateless rotor. Important trailing edge flap and tab design features including index angle, aerodynamic overhang, chord and length are identified through examination of coupled

  5. 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)

  6. 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.

  7. Rotorcraft On-Blade Pressure and Strain Measurements Using Wireless Optical Sensor System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Experimental measurements of rotor blades are important for understanding the aerodynamics and dynamics of a rotorcraft. This understanding can help in solving...

  8. Advances in tilt rotor noise prediction

    Science.gov (United States)

    George, A. R.; Coffen, C. D.; Ringler, T. D.

    The two most serious tilt rotor external noise problems, hover noise and blade-vortex interaction noise, are studied. The results of flow visualization and inflow velocity measurements document a complex, recirculating highly unsteady and turbulent flow due to the rotor-wing-body interactions characteristic of tilt rotors. The wing under the rotor is found to obstruct the inflow, causing a deficit in the inflow velocities over the inboard region of the rotor. Discrete frequency harmonic thickness and loading noise mechanisms in hover are examined by first modeling tilt rotor hover aerodynamics and then applying various noise prediction methods using the WOPWOP code. The analysis indicates that the partial ground plane created by the wing below the rotor results in a primary sound source for hover.

  9. Open Rotor - Analysis of Diagnostic Data

    Science.gov (United States)

    Envia, Edmane

    2011-01-01

    NASA is researching open rotor propulsion as part of its technology research and development plan for addressing the subsonic transport aircraft noise, emission and fuel burn goals. The low-speed wind tunnel test for investigating the aerodynamic and acoustic performance of a benchmark blade set at the approach and takeoff conditions has recently concluded. A high-speed wind tunnel diagnostic test campaign has begun to investigate the performance of this benchmark open rotor blade set at the cruise condition. Databases from both speed regimes will comprise a comprehensive collection of benchmark open rotor data for use in assessing/validating aerodynamic and noise prediction tools (component & system level) as well as providing insights into the physics of open rotors to help guide the development of quieter open rotors.

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

    Energy Technology Data Exchange (ETDEWEB)

    Huether, W.

    1984-03-29

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

  11. Development of tilt-rotor unmanned aerial vehicle (UAV): material selection and structural analysis on wing design

    Science.gov (United States)

    Saharudin, M. F.

    2016-10-01

    This paper presents the design of a tilting rotor unmanned aerial vehicle (UAV), evaluation of flight loads based on the standard requirement, structural analysis to determine stress and sizing of the wing, and flight test of the UAV. The main objective is to perform structural analysis to size the UAV's wing section. The analysis shows that the structure design of the wing is safe to be used.

  12. Numerical Simulation of Bird Impact on the Helicopter Blade by Fluid-structure Coupling Method%采用流固耦合方法的直升机桨叶鸟撞数值模拟

    Institute of Scientific and Technical Information of China (English)

    林长亮; 王浩文; 陈仁良; 尚晓冬

    2012-01-01

    During the process of bird impact on helicopter blades, the relative speed is quite fast and the bird presents the fluid characteristic. So the impact between the bird and helicopter blade is a typical transient fluid-structure coupling dynamics. Firstly, to verify the calculation method and the bird model, the bird impact on aluminum plate test in the literature is analyzed by adopting ALE fluid-solid coupling method. Then numerical simulation of bird impact on the blades is conducted. The numerical simulation results show that the ALE method can accurately simulate and be applied to the process of bird impact on helicopter blade. The detailed analysis to the calculation result such as stress, displacement and impact pressure provides a reference to anti-bird impact on helicopter rotor design.%在鸟撞直升机桨叶过程中,鸟体与桨叶撞击相对速度很大,呈现出流体特性,属于典型的流固耦合瞬态冲击动力学问题.首先针对文献中的鸟撞铝板试验采用ALE流固耦合方法进行了分析,对计算方法与鸟体模型进行了验证.然后进行了桨叶鸟撞数值模拟.数值模拟结果表明ALE方法能够准确模拟鸟撞过程,适用于直升机桨叶鸟撞分析.通过应力、位移以及撞击压力等计算结果的详细分析,对直升机旋翼抗鸟撞设计具有一定的参考价值.

  13. Aerodynamic design of the National Rotor Testbed.

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Christopher Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-10-01

    A new wind turbine blade has been designed for the National Rotor Testbed (NRT) project and for future experiments at the Scaled Wind Farm Technology (SWiFT) facility with a specific focus on scaled wakes. This report shows the aerodynamic design of new blades that can produce a wake that has similitude to utility scale blades despite the difference in size and location in the atmospheric boundary layer. Dimensionless quantities circulation, induction, thrust coefficient, and tip-speed-ratio were kept equal between rotor scales in region 2 of operation. The new NRT design matched the aerodynamic quantities of the most common wind turbine in the United States, the GE 1.5sle turbine with 37c model blades. The NRT blade design is presented along with its performance subject to the winds at SWiFT. The design requirements determined by the SWiFT experimental test campaign are shown to be met.

  14. Flow structure and heat exchange analysis in internal cooling channel of gas turbine blade

    Science.gov (United States)

    Szwaba, Ryszard; Kaczynski, Piotr; Doerffer, Piotr; Telega, Janusz

    2016-08-01

    This paper presents the study of the flow structure and heat transfer, and also their correlations on the four walls of a radial cooling passage model of a gas turbine blade. The investigations focus on heat transfer and aerodynamic measurements in the channel, which is an accurate representation of the configuration used in aeroengines. Correlations for the heat transfer coefficient and the pressure drop used in the design of radial cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include corner fillet, ribs with fillet radii and special orientation. Therefore, this work provides detailed fluid flow and heat transfer data for a model of radial cooling geometry which possesses very realistic features.

  15. Structural dynamics studies of rotating bladed-disk assemblies coupled with flexible shaft motions

    Science.gov (United States)

    Loewy, R. G.; Khader, N.

    1983-01-01

    In order to analyze the dynamic behavior of the first stage compressor/fan of the 'E3' turbofan engine, a classical structural dynamics approach is employed to couple the motions of a flexible bladed disk to a rotating flexible shaft. The analysis accounts for flexible disk displacements which are transverse to the plane of rotation, and radial as well as tangential, and also accounts for rigid disk translations along, and rotations about, axes normal to the undeformed shaft axes. In the case of a wide range of E3 engine shaft flexibilities and speeds, some of the one-diametral node frequencies are shown to be affected by shaft degrees of freedom whose stiffness values are in general range of design practice. Coriolis forces are also found to significantly affect natural frequencies where strong coupling between certain modes is present.

  16. Non-linear vibrations of cracked structures: application to turbine rotors; Vibrations non-lineaires des structures fissurees: application aux rotors de turbines

    Energy Technology Data Exchange (ETDEWEB)

    El Arem, S.

    2006-01-15

    The aim of this work is to study the dynamic response of a cracked rotor to establish some possibilities for early on line crack detection. First, a review on experimental, numerical and analytical works on the dynamics of cracked rotors is given. Then, an original method of calculating the behavior of a cracked beam section in bending with shearing effects is presented. The nonlinear behavior relations are derived from a three-dimensional model taking into account the unilateral contact conditions on the crack's lips. Based on an energy formulation, this method could be applied to any geometry of crack. The exploration by different numerical integration methods of the vibratory response of some models of cracked rotors is presented in the third chapter of this thesis. The un-cracked parts of a rotor are represented by elements of bar or beam type, and the cracked section by a nonlinear spring taking into account the breathing mechanism of the cracks. At the end of this part, an original method of construction of a finite element of a cracked beam is presented. The final chapter is devoted to the analytical study of the system with 2 degrees of freedom. The breathing mechanism of the crack is taken into account by considering specific periodic variation of the global stiffness of the system. The differential equations system is solved using the harmonic balance method. The linear stability of the periodic solutions is studied by the Floquet theory. Some vibratory parameters are proposed as crack indicators. (author)

  17. THE DESIGN OF AXIAL PUMP ROTORS USING THE NUMERICAL METHODS

    Directory of Open Access Journals (Sweden)

    Ali BEAZIT

    2010-06-01

    Full Text Available The researches in rotor theory, the increasing use of computers and the connection between design and manufacturing of rotors, have determined the revaluation and completion of classical rotor geometry. This paper presents practical applications of mathematical description of rotor geometry. A program has been created to describe the rotor geometry for arbitrary shape of the blade. The results can be imported by GAMBIT - a processor for geometry with modeling and mesh generations, to create a mesh needed in hydrodynamics analysis of rotor CFD. The results obtained are applicable in numerical methods and are functionally convenient for CAD/CAM systems.

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

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich; Branner, Kim

    2015-01-01

    Modern wind turbine rotor blades are normally assembled from large parts bonded together by adhesive joints. The structural parts of wind turbine blades are usually made of composite materials, where sandwich core materials as well as fibre composites are used. For most of the modern wind turbine...... 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...... blades the aerodynamically formed outer shell structure is manufactured as an upper and a lower part in separate moulds in order to simplify the production process. The aerodynamic shell structures are then bonded to internal load bearing structures during the production process. Adhesive joints exist...

  19. The Application of the Model Correction Factor Method to a Reliability Analysis of a Composite Blade Structure

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimiroy; Friis-Hansen, Peter; Berggreen, Christian

    2009-01-01

    This paper presents a reliability analysis of a composite blade profile. The so-called Model Correction Factor technique is applied as an effective alternate approach to the response surface technique. The structural reliability is determined by use of a simplified idealised analytical model which...

  20. Numerical Study for Detailed Flow Fields and Performance of the Savonius-Type Rotor

    Science.gov (United States)

    Zhou, Tong; Rempfer, Dietmar

    2011-11-01

    The Savonius-type rotor is simple in structure, has good starting characteristics, relatively low operating speeds, and an ability to accept wind from any direction, although it has a lower efficiency than other vertical axis wind turbines. So far a number of experimental investigations have been carried out to study the performance of the Savonius rotor, however, there is a lack of detailed descriptions of the flow field. The aim of this paper is to numerically explore the non-linear two-dimensional unsteady flow over a Savonius rotor and develop a simulation method for predicting its aerodynamic performance. The simulations are based on Star CCM+. The motion of the blades is solved by using a moving mesh. Different turbulence models are compared. Parameters such as mesh density, wall y+, and boundary conditions will be discussed. Numerical simulation results are compared with experimental data. Separation of the flow at the blade tips is well modeled. The characteristics of flow fields details are studied, including boundary layer, moment coefficient, and pressure distribution. The wall shear on each surface of the blades is studied to look into the position of the separation point. Computational fluid dynamics is proven to be an effective approach for the investigation of the Savonius-type rotor, on the premise of proper theory and reasonable assumption. It also provides a basis for optimization of the Savonius wind turbine.

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

    Science.gov (United States)

    Strnad, Jaromir; Liska, Jindrich

    2015-11-01

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

  2. Tiltrotor research aircraft composite blade repairs: Lessons learned

    Science.gov (United States)

    Espinosa, Paul S.; Groepler, David R.

    1991-01-01

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

  3. Blade Pitch Control for Electrically Controlled Rotor Based on Online Identification of Error Path%电控旋翼的误差通道在线辨识桨距控制

    Institute of Scientific and Technical Information of China (English)

    董维生; 陆洋

    2013-01-01

    为了提高电控旋翼桨距的控制效果,提出了两种基于误差通道在线辨识的自适应滤波控制方法:缩放因子法和约束权函数法.利用桨距开环状态试验数据和最小二乘法辨识得到的控制对象数学模型,完成了两种改进方法的电控旋翼桨距控制仿真.仿真结果表明:缩放因子法在不降低自身自适应性的同时,可以有效地提高电控旋翼的总距及周期变距桨距控制精度和响应速度;约束权函数法则在有效抑制外部噪声干扰的同时提高了控制算法的稳定性.%In order to improve the control efficiency of blade pitch control of Electrically Controlled Rotor (ECR), two methods based on adaptive control method with online identification of error path, scaling factor method and constrained weight method, were proposed. According to the data collected from the open loop pitch control test and the least-squares method, mathematical model of control object was established. Then the ECR pitch control simulation work was conducted for the two proposed methods. Simulation results indicated that; 1 ) the scaling factor method can effectively increase the speed of response and improve the control accuracy of both ECR collective pitch and cyclic pitch control, and keep itself adaptive; and 2) the constrained weight method can effectively restrain the interference caused by the external noise, and can improve the stability of the whole control system at the same time.

  4. Blade life span, structural investment, and nutrient allocation in giant kelp.

    Science.gov (United States)

    Rodriguez, Gabriel E; Reed, Daniel C; Holbrook, Sally J

    2016-10-01

    The turnover of plant biomass largely determines the amount of energy flowing through an ecosystem and understanding the processes that regulate turnover has been of interest to ecologists for decades. Leaf life span theory has proven useful in explaining patterns of leaf turnover in relation to resource availability, but the predictions of this theory have not been tested for macroalgae. We measured blade life span, size, thickness, nitrogen content, pigment content, and maximum photosynthetic rate (P max) in the giant kelp (Macrocystis pyrifera) along a strong resource (light) gradient to test whether the predictions of leaf life span theory applied to this alga. We found that shorter blade life spans and larger blade areas were associated with increased light availability. In addition, nitrogen and P max decreased with blade age, and their decrease was greater in shorter lived blades. These observations are generally consistent with patterns observed for higher plants and the prevailing theory of leaf life span. By contrast, variation observed in pigments of giant kelp was inconsistent with that predicted by leaf life span theory, as blades growing in the most heavily shaded portion of the forest had the lowest chlorophyll content. This result may reflect the dual role of macroalgal blades in carbon fixation and nutrient absorption and the ability of giant kelp to modify blade physiology to optimize the acquisition of light and nutrients. Thus, the marine environment may place demands on resource acquisition and allocation that have not been previously considered with respect to leaf life span optimization.

  5. The New Structure Design and Analysis of Energy Storage of Flywheel of Split Rotor

    Directory of Open Access Journals (Sweden)

    Peng Xu

    2015-02-01

    Full Text Available The braking of the rail transit train consumes a great quantity of energy, and the thermal energy produced in the process of braking can affect the normal operation of the transit train. Thus recycling the braking energy becomes a research hotspot of urban rail train. This paper made an overall analysis of regenerative braking process, the rationale, and the main features and then put forward the optimizing the structure of the composite flywheel concept and design calculation method. This paper also designs a new flywheel structure which can be applied on urban rail operating system. The new flywheel structure should be checked by finite element method and the radius of the rotor should be defined under the condition of meeting the requirements of carbon fiber material strength. Meanwhile, compared with the solid flywheel under the same condition, analysis shows that the maximum rotary inertia of the new flywheel and the quality energy density increased, and the discharge depth also perks up.

  6. Hi-Q Rotor - Low Wind Speed Technology

    Energy Technology Data Exchange (ETDEWEB)

    Todd E. Mills; Judy Tatum

    2010-01-11

    collected, the results of our first full-scale prototype wind turbine proved that higher energy can be captured at lower wind speeds with the new Hi-Q Rotor. The Hi-Q Rotor is almost 15% more productive than the Bergey from 6 m/s to 8 m/s, making it ideal in Class 3, 4, and 5 wind sites and has application in the critical and heretofore untapped areas that are closer to cities, 'load centers,' and may even be used directly in urban areas. The additional advantage of the Hi-Q Rotor's non-conventional blade tips, which eliminates most air turbulence, is noise reduction which makes it doubly ideal for populated urban areas. Hi-Q Products recommends one final stage of development to take the Hi-Q Rotor through Technology Readiness Levels 8-9. During this stage of development, the rotor will be redesigned to further increase efficiency, match the rotor to a more suitable generator, and lower the cost of manufacturing by redesigning the structure to allow for production in larger quantities at lower cost. Before taking the rotor to market and commercialization, it is necessary to further optimize the performance by finding a better generator and autofurling system, ones more suitable for lower wind speeds and rpms should be used in all future testing. The potential impact of this fully developed technology will be the expansion and proliferation of energy renewal into the heretofore untapped Class 2, 3, 4, and 5 Wind Sites, or the large underutilized sites where the wind speed is broken by physical features such as mountains, buildings, and trees. Market estimates by 2011, if low wind speed technology can be developed are well above: 13 million homes, 675,000 commercial buildings, 250,000 public facilities. Estimated commercial exploitation of the Hi-Q Rotor show potential increase in U.S. energy gained through the clean, renewable wind energy found in low and very low wind speed sites. This new energy source would greatly impact greenhouse emissions as well as the

  7. Unsteady aerodynamic interaction effects on turbomachinery blade life and performance

    Science.gov (United States)

    Adamczyk, John J.

    1992-01-01

    This paper is an attempt to address the impact of a class of unsteady flows on the life and performance of turbomachinery blading. These class of flows to be investigated are those whose characteristic frequency is an integral multiple of rotor shaft speed. Analysis of data recorded downstream of a compressor and turbine rotor will reveal that this class of flows can be highly three-dimensional and may lead to the generation of secondary flows within downstream blading. By explicitly accounting for these unsteady flows in the design of turbomachinery blading for multistage applications, it may be possible to bring about gains in performance and blade life.

  8. A structural dynamics study of a wing-pylon-tiltrotor system

    Science.gov (United States)

    Khader, N.; Abu-Mallouh, R.

    1992-12-01

    A simple structural model for a three-bladed tiltrotor-pylon-wing assembly is presented, which accounts for chordwise, transverse, and torsional wing deformations, rigid pylon pitching motion with respect to the wing tip cross-section in its deformed position, lead-lag, flap, and torsional deformations of rotor blades. The model considers equivalent viscous damping associated with blade and wing elastic deformations and with rigid pylon pitching motion. It is established that blade-to wing bending rigidity ratio, pylon pitching frequency, equivalent viscous damping associated with blade elastic deformations, and rotational speed, are the most important design parameters, whose effect on system frequencies and stability boundaries is evaluated.

  9. Theoretical analysis of the flow around a Savonius rotor

    Energy Technology Data Exchange (ETDEWEB)

    Aouachria, Z.; Djoumati, D. [Batna Univ., Batna (Algeria). Laboratoire de Physique Energetique Appliquee; Djamel, H. [Batna Univ., Batna (Algeria). Dept. de Mecanique Energetique

    2009-07-01

    While Savonius rotors do not perform as well as Darrieus wind turbine rotors, Savonius rotors work in all wind directions, do not require a rudder, and are capable of operating at relatively low speeds. A discrete vortex method was used to analyze the complex flow around a Savonius rotor. Velocity and pressure fields obtained in the analysis were used to determine both mechanical and energetic rotor performance. Savonius rotor bi-blades were considered in relation to 4 free eddies, the leakage points of each blade, and the distribution of basic eddies along the blades. Each blade was divided into equal elementary arcs. Linear equations and Kelvin theorem were reduced to a single equation. Results showed good agreement with data obtained in previous experimental studies. The study demonstrated that vortice emissions were unbalanced. The resistant blade had 2 vortice emissions, while the driving blade had only a single vortex. The results of the study will be used to clarify the mechanical and aerodynamic functions as well as to determine the different values between the blades and the speed of the turbine's engine. 9 refs., 4 figs.

  10. Laser profiling of 3D microturbine blades

    Science.gov (United States)

    Holmes, Andrew S.; Heaton, Mark E.; Hong, Guodong; Pullen, Keith R.; Rumsby, Phil T.

    2003-11-01

    We have used KrF excimer laser ablation in the fabrication of a novel MEMS power conversion device based on an axial-flow turbine with an integral axial-flux electromagnetic generator. The device has a sandwich structure, comprising a pair of silicon stators either side of an SU8 polymer rotor. The curved turbine rotor blades were fabricated by projection ablation of SU8 parts performed by conventional UV lithography. A variable aperture mask, implemented by stepping a moving aperture in front of a fixed one, was used to achieve the desired spatial variation in the ablated depth. An automatic process was set up on a commercial laser workstation, with the laser firing and mask motion being controlled by computer. High quality SU8 rotor parts with diameters of 13 mm and depths of 1 mm were produced at a fluence of 0.7 J/cm2, corresponding to a material removal rate of approximately 0.3 μm per pulse. A similar approach was used to form SU8 guide vane inserts for the stators.

  11. Description of the vortex formation on a Savonius rotor in a water channel; Description de l`alternance des tourbillons d`un rotor Savonius par visualisation en tunnel hydrodynamique

    Energy Technology Data Exchange (ETDEWEB)

    Benghrib, D.; Ahram, A. [Universite Choiaib-Doukkali, Faculte des Sciences, El Jadida (Morocco); Bchir, L. [Universite Cadi-Ayyad, Faculte des Sciences Samlalia, Marrakech (Morocco)

    1998-08-01

    We study the vortex formation of a Savonius rotor `propulsive` blade. Particularly we describe the different events happening during a half period of rotation by means of chrono-photography technics. A film has been registered from visualisation in a water channel with the dye emitted from the centre of the rotor. The rotor blade is in plexiglas and we have been able to detect the different fluid motions on each side of the curved propulsive blade. (authors) 12 refs.

  12. Metal Foam Analysis: Improving Sandwich Structure Technology for Engine Fan and Propeller Blades

    Science.gov (United States)

    Fedor, Jessica L.

    2004-01-01

    The Life Prediction Branch of the NASA Glenn Research Center is searching for ways to construct aircraft and rotorcraft engine fan and propeller blades that are lighter and less costly. One possible design is to create a sandwich structure composed of two metal faces sheets and a metal foam core. The face sheets would carry the bending loads and the foam core would have to resist the transverse shear loads. Metal foam is ideal because of its low density and energy absorption capabilities, making the structure lighter, yet still stiff. The material chosen for the face sheets and core was 17-4PH stainless steel, which is easy to make and has appealing mechanical properties. This material can be made inexpensively compared to titanium and polymer matrix composites, the two current fan blade alternatives. Initial tests were performed on design models, including vibration and stress analysis. These tests revealed that the design is competitive with existing designs; however, some problems were apparent that must be addressed before it can be implemented in new technology. The foam did not hold up as well as expected under stress. This could be due to a number of issues, but was most likely a result of a large number of pores within the steel that weakened the structure. The brazing between the face sheets and the foam was also identified as a concern. The braze did not hold up well under shear stress causing the foam to break away from the face sheets. My role in this project was to analyze different options for improving the design. I primarily spent my time examining various foam samples, created with different sintering conditions, to see which exhibited the most favorable characteristics for our purpose. Methods of analysis that I employed included examining strut integrity under a microscope, counting the number of cells per inch, measuring the density, testing the microhardness, and testing the strength under compression. Shear testing will also be done to examine

  13. Diagnosis of wind turbine rotor system

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Mirzaei, Mahmood; Henriksen, Lars Christian

    2016-01-01

    This paper describes a model free method for monitoring and fault diagnosis of the elements in a rotor system for a wind turbine. The diagnosis as well as the monitoring is done without using any model of the wind turbine and the applied controller or a description of the wind profile. The method...... is based on available standard sensors on wind turbines. The method can be used both on-line as well as off-line. Faults or changes in the rotor system will result in asymmetries, which can be monitored and diagnosed. This can be done by using the multi-blade coordinate transformation. Changes in the rotor...... system that can be diagnosed and monitored are: actuator faults, sensor faults and internal blade changes as e.g. change in mass of a blade....

  14. Structure simulation in unidirectionally solidified turbine blade by dendrite envelope tracking model (Ⅱ): model validation and defects prediction

    Institute of Scientific and Technical Information of China (English)

    WANG Tong-min; SU Yan-qing; GUO Jing-jie; I. OHNAKA; H. YASUDA

    2006-01-01

    The developed model was validated by the checking of grain preferential growth orientation and the solidification experiment with low melting point alloy of Sn-21%Bi(mole fraction). It was also applied to predict the structure defects (e.g. stray grain) of unidirectionally solidified turbine blade. The results show that the developed model is reliable and has the following abilities: 1) reduce the misorientation caused by the orthogonal mesh used in simulation; 2) well reproduce the growth competition among the different-preferential-direction grains with less than 10% relative error; 3) predict the structure defect of stray grain with the accuracy over 80%; 4) optimize the grain selector to better obtain a single crystal avoiding the multigrain defect; 5) simulate the structure evolution (nucleation and growth) of the directional and single crystal turbine blade.

  15. Structural Health Monitoring of Wind Turbine Blades: Acoustic Source Localization Using Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Omar Mabrok Bouzid

    2015-01-01

    Full Text Available Structural health monitoring (SHM is important for reducing the maintenance and operation cost of safety-critical components and systems in offshore wind turbines. This paper proposes an in situ wireless SHM system based on an acoustic emission (AE technique. By using this technique a number of challenges are introduced due to high sampling rate requirements, limitations in the communication bandwidth, memory space, and power resources. To overcome these challenges, this paper focused on two elements: (1 the use of an in situ wireless SHM technique in conjunction with the utilization of low sampling rates; (2 localization of acoustic sources which could emulate impact damage or audible cracks caused by different objects, such as tools, bird strikes, or strong hail, all of which represent abrupt AE events and could affect the structural health of a monitored wind turbine blade. The localization process is performed using features extracted from aliased AE signals based on a developed constraint localization model. To validate the performance of these elements, the proposed system was tested by testing the localization of the emulated AE sources acquired in the field.

  16. Surface-Mount Rotor Motion Sensing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A surface-mounted instrumentation system for measuring rotor blade motions on rotorcraft, for use both in flight and in wind tunnel testing, is proposed for...

  17. A Surface-Mounted Rotor State Sensing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A surface-mounted instrumentation system for measuring rotor blade motions on rotorcraft, for use both in flight and in wind tunnel testing, is proposed for...

  18. Structural damage detection in wind turbine blades based on time series representations of dynamic responses

    Science.gov (United States)

    Hoell, Simon; Omenzetter, Piotr

    2015-03-01

    The development of large wind turbines that enable to harvest energy more efficiently is a consequence of the increasing demand for renewables in the world. To optimize the potential energy output, light and flexible wind turbine blades (WTBs) are designed. However, the higher flexibilities and lower buckling capacities adversely affect the long-term safety and reliability of WTBs, and thus the increased operation and maintenance costs reduce the expected revenue. Effective structural health monitoring techniques can help to counteract this by limiting inspection efforts and avoiding unplanned maintenance actions. Vibration-based methods deserve high attention due to the moderate instrumentation efforts and the applicability for in-service measurements. The present paper proposes the use of cross-correlations (CCs) of acceleration responses between sensors at different locations for structural damage detection in WTBs. CCs were in the past successfully applied for damage detection in numerical and experimental beam structures while utilizing only single lags between the signals. The present approach uses vectors of CC coefficients for multiple lags between measurements of two selected sensors taken from multiple possible combinations of sensors. To reduce the dimensionality of the damage sensitive feature (DSF) vectors, principal component analysis is performed. The optimal number of principal components (PCs) is chosen with respect to a statistical threshold. Finally, the detection phase uses the selected PCs of the healthy structure to calculate scores from a current DSF vector, where statistical hypothesis testing is performed for making a decision about the current structural state. The method is applied to laboratory experiments conducted on a small WTB with non-destructive damage scenarios.

  19. Fluid flow modeling of resin transfer molding for composite material wind turbine blade structures.

    Energy Technology Data Exchange (ETDEWEB)

    Cairns, Douglas S. (Montana State University, Bozeman, MT); Rossel, Scott M. (Montana State University, Bozeman, MT)

    2004-06-01

    Resin transfer molding (RTM) is a closed mold process for making composite materials. It has the potential to produce parts more cost effectively than hand lay-up or other methods. However, fluid flow tends to be unpredictable and parts the size of a wind turbine blade are difficult to engineer without some predictive method for resin flow. There were five goals of this study. The first was to determine permeabilities for three fabrics commonly used for RTM over a useful range of fiber volume fractions. Next, relations to estimate permeabilities in mixed fabric lay-ups were evaluated. Flow in blade substructures was analyzed and compared to predictions. Flow in a full-scale blade was predicted and substructure results were used to validate the accuracy of a full-scale blade prediction.

  20. An experimental and analytical investigation of isolated rotor flap-lag stability in forward flight

    Science.gov (United States)

    Gaonkar, Gopal H.; Mcnulty, Michael J.; Nagabhushanam, J.

    1990-01-01

    The flap-lag stability of an isolated hingeless rotor is investigated, both experimentally and analytically, in hover and in forward flight. The effects of forward flight aerodynamics on regressing lead-lag mode stability are the focus of the investigation. The soft-inplane, three-bladed, isolated model rotor was operated untrimmed at advance ratios from hover to 0.55 and at shaft angles as high as 20 deg. The experimental data base includes forward flight damping data for two lead-lag natural frequencies, for three values of collective pitch, and for both zero and full-lag structural coupling. With the aid of computerized symbolic manipulation, a rigid-blade lag-flap model analysis was developed to calculate the Floquent eigenvalues and to identify the modes. Good correlation is shown for some cases, but other cases show large discrepancies between the theory and experiment.