WorldWideScience

Sample records for aerodynamic blade optimisation

  1. Noise aspects at aerodynamic blade optimisation projects

    International Nuclear Information System (INIS)

    The Netherlands Energy Research Foundation (ECN) has often been involved in industrial projects, in which blade geometries are created automatic by means of numerical optimisation. Usually, these projects aim at the determination of the aerodynamic optimal wind turbine blade, i.e. the goal is to design a blade which is optimal with regard to energy yield. In other cases, blades have been designed which are optimal with regard to cost of generated energy. However, it is obvious that the wind turbine blade designs which result from these optimisations, are not necessarily optimal with regard to noise emission. In this paper an example is shown of an aerodynamic blade optimisation, using the ECN-program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. 11 figs., 8 refs

  2. Noise aspects at aerodynamic blade optimisation projects

    Energy Technology Data Exchange (ETDEWEB)

    Schepers, J.G. [Netherlands Energy Research Foundation, Petten (Netherlands)

    1997-12-31

    This paper shows an example of an aerodynamic blade optimisation, using the program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. The aerodynamic optimised geometry from PVOPT is the `real` optimum (up to the latest decimal). The most important conclusion from this study is, that it is worthwhile to investigate the behaviour of the objective function (in the present case the energy yield) around the optimum: If the optimum is flat, there is a possibility to apply modifications to the optimum configuration with only a limited loss in energy yield. It is obvious that the modified configurations emits a different (and possibly lower) noise level. In the BLADOPT program (the successor of PVOPT) it will be possible to quantify the noise level and hence to assess the reduced noise emission more thoroughly. At present the most promising approaches for noise reduction are believed to be a reduction of the rotor speed (if at all possible), and a reduction of the tip angle by means of low lift profiles, or decreased twist at the outboard stations. These modifications were possible without a significant loss in energy yield. (LN)

  3. 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...

  4. Study on Aerodynamic Design Optimization of Turbomachinery Blades

    Institute of Scientific and Technical Information of China (English)

    Naixing CHEN; Hongwu ZHANG; Weiguang HUANG; Yanji XU

    2005-01-01

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

  5. AERODYNAMIC AND BLADING DESIGN OF MULTISTAGE AXIAL FLOW COMPRESSORS

    Science.gov (United States)

    Crouse, J. E.

    1994-01-01

    The axial-flow compressor is used for aircraft engines because it has distinct configuration and performance advantages over other compressor types. However, good potential performance is not easily obtained. The designer must be able to model the actual flows well enough to adequately predict aerodynamic performance. This computer program has been developed for computing the aerodynamic design of a multistage axial-flow compressor and, if desired, the associated blading geometry input for internal flow analysis. The aerodynamic solution gives velocity diagrams on selected streamlines of revolution at the blade row edges. The program yields aerodynamic and blading design results that can be directly used by flow and mechanical analysis codes. Two such codes are TSONIC, a blade-to-blade channel flow analysis code (COSMIC program LEW-10977), and MERIDL, a more detailed hub-to-shroud flow analysis code (COSMIC program LEW-12966). The aerodynamic and blading design program can reduce the time and effort required to obtain acceptable multistage axial-flow compressor configurations by generating good initial solutions and by being compatible with available analysis codes. The aerodynamic solution assumes steady, axisymmetric flow so that the problem is reduced to solving the two-dimensional flow field in the meridional plane. The streamline curvature method is used for the iterative aerodynamic solution at stations outside of the blade rows. If a blade design is desired, the blade elements are defined and stacked within the aerodynamic solution iteration. The blade element inlet and outlet angles are established by empirical incidence and deviation angles to the relative flow angles of the velocity diagrams. The blade element centerline is composed of two segments tangentially joined at a transition point. The local blade angle variation of each element can be specified as a fourth-degree polynomial function of path distance. Blade element thickness can also be specified

  6. 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.

  7. Aerodynamic investigation of winglets on wind turbine blades using CFD

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Sørensen, Niels N.

    2006-01-01

    The present report describes the numerical investigation of the aerodynamics around a wind turbine blade with a winglet using Computational Fluid Dynamics, CFD. Five winglets were investigated with different twist distribution and camber. Four of them were pointing towards the pressure side...... (upstream) and one was pointing towards the suction side (downstream). Additionally, a rectangular modification of the original blade tip was designed with the same planform area as the blades with winglets. Results show that adding a winglet to the existing blade increase the force distribution on the...

  8. An aerodynamic study on flexed blades for VAWT applications

    International Nuclear Information System (INIS)

    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

  9. Tip Cascade Aerodynamics of Turbine Rotor Blade 1220 mm

    Czech Academy of Sciences Publication Activity Database

    Rudas, B.; Synáč, J.; Šťastný, M.; Luxa, Martin; Šimurda, David; Šafařík, Pavel

    Plzeň: Západočeská univerzita v Plzni, 2010, s. 1-6. ISBN N. [Turbostroje 2010. Plzeň (CZ), 22.09.2010-23.09.2010] Institutional research plan: CEZ:AV0Z20760514 Keywords : tip blade cascade * CFD simulation * high-speed aerodynamic Subject RIV: BK - Fluid Dynamics

  10. Numerical simulation on the aerodynamic effects of blade icing on small scale Straight-bladed VAWT

    Science.gov (United States)

    Feng, Fang; Li, Shengmao; Li, Yan; Tian, Wenqiang

    To invest the effects of blade surface icing on the aerodynamics performance of the straight-bladed vertical-axis wind turbine (SB-VAWT), wind tunnel tests were carried out on a static straight blade using a simple icing wind tunnel. Firstly, the icing situations on blade surface at some kinds of typical attack angle were observed and recorded under different cold water flow fluxes. Then the iced blade airfoils were combined into a SB-VAWT model with two blades. Numerical simulations were carried out on this model, and the static and dynamic torque coefficients of the model with and without icing were computed. Both the static and dynamic torque coefficients were decreased for the icing effects.

  11. Aerodynamic Research on the Midsection of a Long Turbine Blade

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Šafařík, Pavel; Synáč, J.

    Gdansk: Instytut Maszyn Przeplywowych PAN, 2008 - (Doerffer, P.; Szwaba, R.), s. 147-148 ISBN 978-83-88237-41-6. [Krajowa Konferencja Mechaniki Plynów /18./. Jastrzebia Góra (PL), 21.09.2008-25.09.2008] R&D Projects: GA ČR GA101/07/1508 Institutional research plan: CEZ:AV0Z20760514 Keywords : high speed aerodynamics * blade cascade * experiment Subject RIV: BK - Fluid Dynamics

  12. Aerodynamic Research on the Midsection of a Long Turbine Blade

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Šafařík, Pavel; Synáč, J.

    2008-01-01

    Roč. 12, 3-4 (2008), s. 135-145. ISSN 1428-6394. [Polish National Conference of Fluid Mechanics /18./. Jastrzebia Góra, 21.09.2008-25.09.2008] R&D Projects: GA ČR GA101/07/1508 Institutional research plan: CEZ:AV0Z20760514 Keywords : high speed aerodynamics * blade cascade * experiment Subject RIV: BK - Fluid Dynamics

  13. Tip Cascade Aerodynamics of Turbine Rotor Blade 1220mm

    Czech Academy of Sciences Publication Activity Database

    Synáč, J.; Rudas, B.; Šťastný, M.; Luxa, Martin; Šimurda, David; Šafařík, Pavel

    Praha: TechSoft Engineering s.r.o., 2009 - (Moštěk, M.), s. 37-45 ISBN 978-80-254-4651-5. [Současné trendy při návrhu a výpočtu turbostrojů. Praha (CZ), 02.06.2009-04.06.2009] Institutional research plan: CEZ:AV0Z20760514 Keywords : aerodynamics * blade cascade * transonic flow * loss * turbine Subject RIV: BK - Fluid Dynamics

  14. High Speed Aerodynamic Research on Root Blade Cascade

    Czech Academy of Sciences Publication Activity Database

    Luxa, Martin; Synáč, J.; Šafařík, Pavel; Šimurda, David

    Praha: ÚT AV ČR, v. v. i., 2007 - (Příhoda, J.; Kozel, K.), s. 111-114 ISBN 978-80-87012-04-8. [Conference TOPICAL PROBLEMS OF FLUID MECHANICS 2007. Praha (CZ), 28.02.2007-02.03.2007] R&D Projects: GA ČR GA101/07/1508 Institutional research plan: CEZ:AV0Z20760514 Keywords : root blade cascade * transsonic flow * aerodynamic research Subject RIV: BK - Fluid Dynamics

  15. Experimental Characterization of Wind Turbine Blade Aerodynamic Noise

    Science.gov (United States)

    Ingemanson, Megan Lynn

    Wind turbine noise at low frequencies less than 300Hz is not only annoying to humans but has been proven to cause serious health issues. Additionally, animals are severely affected by wind turbines because a small increase in ambient noise (as is produced by wind turbines) significantly reduces their listening ability. In an attempt to better understand and characterize the aerodynamic noise of wind turbine blades, experimental testing was completed on PowerWorks 100kW and GudCraft WG700 blade specimens in the University of California, Davis Transportation Noise Control Center's anechoic chamber. Experimental testing and data analysis proved approximately 4.0dB to 6.0dB was produced due to the blades' geometric design for both blade specimens at low frequencies. This noise was maximized at the blades' leading edge along the central portion of the blades' radius. Theoretical prediction models have been used to determine that, for typical wind speeds and low frequencies, noise generated due to the tip passing frequency is clearly predominant.

  16. Fully integrated aerodynamic/dynamic optimization of helicopter rotor blades

    Science.gov (United States)

    Walsh, Joanne L.; Lamarsh, William J., II; Adelman, Howard M.

    1992-01-01

    A fully integrated aerodynamic/dynamic optimization procedure is described for helicopter rotor blades. The procedure combines performance and dynamic analyses with a general purpose optimizer. The procedure minimizes a linear combination of power required (in hover, forward flight, and maneuver) and vibratory hub shear. The design variables include pretwist, taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Aerodynamic constraints consist of limits on power required in hover, forward flight and maneuvers; airfoil section stall; drag divergence Mach number; minimum tip chord; and trim. Dynamic constraints are on frequencies, minimum autorotational inertia, and maximum blade weight. The procedure is demonstrated for two cases. In the first case, the objective function involves power required (in hover, forward flight and maneuver) and dynamics. The second case involves only hover power and dynamics. The designs from the integrated procedure are compared with designs from a sequential optimization approach in which the blade is first optimized for performance and then for dynamics. In both cases, the integrated approach is superior.

  17. Time domain analysis method for aerodynamic noises from wind turbine blades

    Directory of Open Access Journals (Sweden)

    Hua ZHAO

    2015-04-01

    Full Text Available The issue of the aerodynamic noises from wind turbine blades affecting the surrounding residents life begins to attract researcher's attention. Most of the existing researches are based on CFD software or experimental data fitting method to analyze the aerodynamic noises, so it is difficult to adapt the demand to dynamic analysis of the aerodynamic noises from wind speed variation. In this paper, the operation parameters, the inflow wind speed and the receiver location are considered, and a modified model to calculate aerodynamic noises from wind turbine blades which is based on traditional acoustic formulas is established. The program to calculate the aerodynamic noises from the 2 MW wind turbine blades is compiled using a time-domain analysis method based on the Simulink modular in Matlab software. And the pressure time sequence diagrams of the aerodynamic noises from wind turbine blades are drawn. It has provided a theoretical foundation to develop low noise wind turbine blades.

  18. AERODYNAMIC RESEARCH ON THE MCA – TYPE COMPRESSOR BLADE CASCADE

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Šafařík, P.

    Glasgow : ASME, 2010, s. 99-108. ISBN 978-0-7918-4402-1. [ASME Turbo Expo 2010. Glasgow (GB), 14.06.2010-18.06.2010] R&D Projects: GA AV ČR(CZ) IAA200760801; GA ČR(CZ) GA101/08/0623; GA ČR(CZ) GAP101/10/1329 Institutional research plan: CEZ:AV0Z20760514 Keywords : compressor blade cascade * transonic flow * aerodynamic research Subject RIV: BK - Fluid Dynamics http://www.asmeconferences.org/TE10/ConfSpecInfo.cfm

  19. Tip Cascade Aerodynamics of Turbine Stage Blades 48"

    Czech Academy of Sciences Publication Activity Database

    Synáč, J.; Rudas, B.; Šťastný, M.; Luxa, Martin; Šimurda, David; Šafařík, Pavel

    Vol. 8. Graz: Technischen Universität Graz, 2009 - (Heitmeir, F.; Martelli, F.; Manna, M.), s. 1449-1457 ISBN 978-3-85125-036-7. [Turbomachinery Fluid Dynamics and Thermodynamics /8./. Graz (AT), 23.03.2009-27.03.2009] R&D Projects: GA ČR(CZ) GA101/08/0623; GA ČR GA101/07/1508 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerodynamics * tip section * blade cascade Subject RIV: BK - Fluid Dynamics

  20. Blade Design Optimisation for Fixed-Pitch Fixed-Speed Wind Turbines

    OpenAIRE

    Lin Wang; Xinzi Tang; Xiongwei Liu

    2012-01-01

    Fixed-pitch fixed-speed (FPFS) wind turbines have some distinct advantages over other topologies for small wind turbines, particularly for low wind speed sites. The blade design of FPFS wind turbines is fundamentally different to fixed-pitch variable-speed wind turbine blade design. Theoretically, it is difficult to obtain a global mathematical solution for the blade design optimisation. Through case studies of a given baseline wind turbine and its blade airfoil, this paper aims to demonstrat...

  1. Measurement of Unsteady Aerodynamics Load on the Blade of Field Horizontal Axis Wind Turbine

    Science.gov (United States)

    Kamada, Yasunari; Maeda, Takao; Naito, Keita; Ouchi, Yuu; Kozawa, Masayoshi

    This paper describes an experimental field study of the rotor aerodynamics of wind turbines. The test wind turbine is a horizontal axis wind turbine, or: HAWT with a diameter of 10m. The pressure distributions on the rotating blade are measured with multi point pressure transducers. Sectional aerodynamic forces are analyzed from pressure distribution. Blade root moments are measured simultaneously by a pair of strain gauges. The inflow wind is measured by a three component sonic anemometer, the local inflow of the blade section are measured by a pair of 7 hole Pitot tubes. The relation between the aerodynamic moments on the blade root from pressure distribution and the mechanical moment from strain gauges is discussed. The aerodynamic moments are estimated from the sectional aerodynamic forces and show oscillation caused by local wind speed and direction change. The mechanical moment shows similar oscillation to the aerodynamic excepting the short period oscillation of the blade first mode frequency. The fluctuation of the sectional aerodynamic force triggers resonant blade oscillations. Where stall is present along the blade section, the blade's first mode frequency is dominant. Without stall, the rotating frequency is dominant in the blade root moment.

  2. Advanced multistage turbine blade aerodynamics, performance, cooling, and heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Fleeter, S.; Lawless, P.B. [Purdue Univ., West Lafayette, IN (United States)

    1995-10-01

    The gas turbine has the potential for power production at the highest possible efficiency. The challenge is to ensure that gas turbines operate at the optimum efficiency so as to use the least fuel and produce minimum emissions. A key component to meeting this challenge is the turbine. Turbine performance, both aerodynamics and heat transfer, is one of the barrier advanced gas turbine development technologies. This is a result of the complex, highly three-dimensional and unsteady flow phenomena in the turbine. Improved turbine aerodynamic performance has been achieved with three-dimensional highly-loaded airfoil designs, accomplished utilizing Euler or Navier-Stokes Computational Fluid Dynamics (CFD) codes. These design codes consider steady flow through isolated blade rows. Thus they do not account for unsteady flow effects. However, unsteady flow effects have a significant impact on performance. Also, CFD codes predict the complete flow field. The experimental verification of these codes has traditionally been accomplished with point data - not corresponding plane field measurements. Thus, although advanced CFD predictions of the highly complex and three-dimensional turbine flow fields are available, corresponding data are not. To improve the design capability for high temperature turbines, a detailed understanding of the highly unsteady and three-dimensional flow through multi-stage turbines is necessary. Thus, unique data are required which quantify the unsteady three-dimensional flow through multi-stage turbine blade rows, including the effect of the film coolant flow. This requires experiments in appropriate research facilities in which complete flow field data, not only point measurements, are obtained and analyzed. Also, as design CFD codes do not account for unsteady flow effects, the next logical challenge and the current thrust in CFD code development is multiple-stage analyses that account for the interactions between neighboring blade rows.

  3. First-order aerodynamic and aeroelastic behavior of a single-blade installation setup

    Science.gov (United States)

    Gaunaa, M.; Bergami, L.; Guntur, S.; Zahle, F.

    2014-06-01

    Limitations on the wind speed at which blade installation can be performed bears important financial consequences. The installation cost of a wind farm could be significantly reduced by increasing the wind speed at which blade mounting operations can be carried out. This work characterizes the first-order aerodynamic and aeroelastic behavior of a single blade installation system, where the blade is grabbed by a yoke, which is lifted by the crane and stabilized by two taglines. A simple engineering model is formulated to describe the aerodynamic forcing on the blade subject to turbulent wind of arbitrary direction. The model is coupled with a schematic aeroelastic representation of the taglines system, which returns the minimum line tension required to compensate for the aerodynamic forcing. The simplified models are in excellent agreement with the aeroelastic code HAWC2, and provide a solid basis for future design of an upgraded single blade installation system able to operate at higher wind speeds.

  4. First-order aerodynamic and aeroelastic behavior of a single-blade installation setup

    International Nuclear Information System (INIS)

    Limitations on the wind speed at which blade installation can be performed bears important financial consequences. The installation cost of a wind farm could be significantly reduced by increasing the wind speed at which blade mounting operations can be carried out. This work characterizes the first-order aerodynamic and aeroelastic behavior of a single blade installation system, where the blade is grabbed by a yoke, which is lifted by the crane and stabilized by two taglines. A simple engineering model is formulated to describe the aerodynamic forcing on the blade subject to turbulent wind of arbitrary direction. The model is coupled with a schematic aeroelastic representation of the taglines system, which returns the minimum line tension required to compensate for the aerodynamic forcing. The simplified models are in excellent agreement with the aeroelastic code HAWC2, and provide a solid basis for future design of an upgraded single blade installation system able to operate at higher wind speeds

  5. First-order aerodynamic and aeroelastic behavior of a single-blade installation setup

    DEFF Research Database (Denmark)

    Gaunaa, Mac; Bergami, Leonardo; Guntur, Srinivas;

    2014-01-01

    of arbitrary direction. The model is coupled with a schematic aeroelastic representation of the taglines system, which returns the minimum line tension required to compensate for the aerodynamic forcing. The simplified models are in excellent agreement with the aeroelastic code HAWC2, and provide a...... first-order aerodynamic and aeroelastic behavior of a single blade installation system, where the blade is grabbed by a yoke, which is lifted by the crane and stabilized by two taglines. A simple engineering model is formulated to describe the aerodynamic forcing on the blade subject to turbulent wind...

  6. Computational Elements for High-fidelity Aerodynamic Analysis and Design Optimisation

    Directory of Open Access Journals (Sweden)

    Chongam Kim

    2010-10-01

    Full Text Available The study reviews the role of computational fluid dynamics (CFD in aerodynamic shape optimisation, and discusses some of the efficient design methodologies. The article in the first part, numerical schemes required for high-fidelity aerodynamic flow analysis are discussed. To accurately resolve high-speed flow physics, high-fidelity shock-stable schemes as well as intelligent limiting strategy mimicking multi-dimensional flow physics are essential. Exploiting these numerical schemes, some applications for 3-D internal/external flow analyses were carried out with various grid systems which enable the treatment of complex geometries. In the second part, depending on the number of design variables and the way to obtain sensitivities or design points, several global and local optimisation methods for aerodynamic shape optimisation are discussed. To avoid the problem that solutions of gradient-based optimisation method (GBOM, are often trapped in local optimum, remedy by combining GBOM with global optimum strategy, such as surrogate models and genetic algorithm (GA has been examined. As an efficient grid deformation tool, grid deformation technique using NURBS function is discussed. Lastly, some 3-D examples for aerodynamic shape optimisation works based on the proposed design methodology are presented.Defence Science Journal, 2010, 60(6, pp.628-638, DOI:http://dx.doi.org/10.14429/dsj.60.581

  7. Straight—Leaned Blade Aerodynamics of A Turbine Nozzle Blade Row with Low Span—Diameter Ratio

    Institute of Scientific and Technical Information of China (English)

    N.X.Chen; Y.J.Xu; 等

    2000-01-01

    Compound-leaned blades have been applied for the design of turbomachinery for reducing secondary flow losses and then improving the aerodynamic performance.The aerodynamics features are not clear enough so far and ,therefore,have been investigated by many authors experimentally and numerically.The present study on turbomachinery aerodynamics is emphasized on the leaning effects of straight-leaned turbine nozzle blades with low span-diameter ratio(less than 0.1) .This kind of blades has relatively low efficiency,This is due to that the blades are too short and then the loss contours of both tip and hub surfaces are merged with each other.How to increase the efficiency becomes one of the important subjects,which is faced to the turbomachinery community,Effects of straight-leaned blades in a turbine nozzle blade row with low span-diameter ratio have been assessed using three-dimensional steady Reynolds-averaged Navier-Stokes computations.

  8. Structural optimisation of vertical-axis wind turbine composite blades based on finite element analysis and genetic algorithm

    OpenAIRE

    Wang, Lin; Kolios, Athanasios; Nishino, Takafumi; DELAFIN, Pierre-Luc; Bird, Theodore

    2016-01-01

    A wind turbine blade generally has complex structures including several layers of composite materials with shear webs, making its structure design very challenging. In this paper, a structural optimisation model for wind turbine composite blades has been developed based on a parametric FEA (finite element analysis) model and a GA (genetic algorithm) model. The optimisation model minimises the mass of composite blades with multi-criteria constraints. The number of unidirectional plies, the loc...

  9. Aerodynamic and Structural Integrated Optimization Design of Horizontal-Axis Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    2016-01-01

    Full Text Available A procedure based on MATLAB combined with ANSYS is presented and utilized for the aerodynamic and structural integrated optimization design of Horizontal-Axis Wind Turbine (HAWT blades. Three modules are used for this purpose: an aerodynamic analysis module using the Blade Element Momentum (BEM theory, a structural analysis module employing the Finite Element Method (FEM and a multi-objective optimization module utilizing the non-dominated sorting genetic algorithm. The former two provide a sufficiently accurate solution of the aerodynamic and structural performances of the blade; the latter handles the design variables of the optimization problem, namely, the main geometrical shape and structural parameters of the blade, and promotes function optimization. The scope of the procedure is to achieve the best trade-off performances between the maximum Annual Energy Production (AEP and the minimum blade mass under various design requirements. To prove the efficiency and reliability of the procedure, a commercial 1.5 megawatt (MW HAWT blade is used as a case study. Compared with the original scheme, the optimization results show great improvements for the overall performance of the blade.

  10. Aerodynamic analysis of different wind-turbine-blade profiles using finite-volume method

    International Nuclear Information System (INIS)

    Highlights: ► The aerodynamic analysis of the S-series blade profiles is performed by CFD. ► The S825, S826, S830 and S831 profiles are the most efficient S-series profiles. ► These profiles are suitable for wind turbines working at low and high wind speeds. ► The optimum operating angle of attack should lie between −4° and 3°. - Abstract: In order to economically gain the maximum energy from the wind turbine, the performance of the blade profile must be obtained. In this paper, the results of aerodynamic simulations of the steady low-speed flow past two-dimensional S-series wind-turbine-blade profiles, developed by the National Renewable Energy Laboratory (NREL), are presented. The aerodynamic simulations were performed using a Computational Fluid Dynamics (CFD) method based on the finite-volume approach. The governing equations used in the simulations are the Reynolds-Averaged-Navier–Stokes (RANS) equations. The wind conditions during the simulations were developed from the wind speeds over different sites in Egypt. The lift and drag forces are the most important parameters in studying the wind-turbine performance. Therefore, an attempt to study the lift and drag forces on the wind turbine blades at various sections is presented. The maximum sliding ratio (lift/drag ratio) is desired in order to gain the maximum power from the wind turbine. The performance of different blade profiles at different wind speeds was investigated and the optimum blade profile for each wind speed is determined based on the maximum sliding ratio. Moreover, the optimum Angle Of Attack (AOA) for each blade profile is determined at the different wind speeds. The numerical results are benchmarked against wind tunnel measurements. The comparisons show that the CFD code used in this study can accurately predict the wind-turbine blades aerodynamic loads.

  11. Experimental and Numerical Study of the Aerodynamic Characteristics of an Archimedes Spiral Wind Turbine Blade

    OpenAIRE

    Kyung Chun Kim; Ho Seong Ji; Yoon Kee Kim; Qian Lu; Joon Ho Baek; Rinus Mieremet

    2014-01-01

    A new type of horizontal axis wind turbine adopting the Archimedes spiral blade is introduced for urban-use. Based on the angular momentum conservation law, the design formula for the blade was derived using a variety of shape factors. The aerodynamic characteristics and performance of the designed Archimedes wind turbine were examined using computational fluid dynamics (CFD) simulations. The CFD simulations showed that the new type of wind turbine produced a power coefficient (C p ) of appro...

  12. Shape optimization of turbine blades with the integration of aerodynamics and heat transfer

    Directory of Open Access Journals (Sweden)

    Rajadas J. N.

    1998-01-01

    Full Text Available A multidisciplinary optimization procedure, with the integration of aerodynamic and heat transfer criteria, has been developed for the design of gas turbine blades. Two different optimization formulations have been used. In the first formulation, the maximum temperature in the blade section is chosen as the objective function to be minimized. An upper bound constraint is imposed on the blade average temperature and a lower bound constraint is imposed on the blade tangential force coefficient. In the second formulation, the blade average and maximum temperatures are chosen as objective functions. In both formulations, bounds are imposed on the velocity gradients at several points along the surface of the airfoil to eliminate leading edge velocity spikes which deteriorate aerodynamic performance. Shape optimization is performed using the blade external and coolant path geometric parameters as design variables. Aerodynamic analysis is performed using a panel code. Heat transfer analysis is performed using the finite element method. A gradient based procedure in conjunction with an approximate analysis technique is used for optimization. The results obtained using both optimization techniques are compared with a reference geometry. Both techniques yield significant improvements with the multiobjective formulation resulting in slightly superior design.

  13. Relevance of aerodynamic modelling for load reduction control strategies of two-bladed wind turbines

    International Nuclear Information System (INIS)

    A new load reduction concept is being developed for the two-bladed prototype of the Skywind 3.5MW wind turbine. Due to transport and installation advantages both offshore and in complex terrain two-bladed turbine designs are potentially more cost-effective than comparable three-bladed configurations. A disadvantage of two-bladed wind turbines is the increased fatigue loading, which is a result of asymmetrically distributed rotor forces. The innovative load reduction concept of the Skywind prototype consists of a combination of cyclic pitch control and tumbling rotor kinematics to mitigate periodic structural loading. Aerodynamic design tools must be able to model correctly the advanced dynamics of the rotor. In this paper the impact of the aerodynamic modelling approach is investigated for critical operational modes of a two-bladed wind turbine. Using a lifting line free wake vortex code (FVM) the physical limitations of the classical blade element momentum theory (BEM) can be evaluated. During regular operation vertical shear and yawed inflow are the main contributors to periodic blade load asymmetry. It is shown that the near wake interaction of the blades under such conditions is not fully captured by the correction models of BEM approach. The differing prediction of local induction causes a high fatigue load uncertainty especially for two-bladed turbines. The implementation of both cyclic pitch control and a tumbling rotor can mitigate the fatigue loading by increasing the aerodynamic and structural damping. The influence of the time and space variant vorticity distribution in the near wake is evaluated in detail for different cyclic pitch control functions and tumble dynamics respectively. It is demonstrated that dynamic inflow as well as wake blade interaction have a significant impact on the calculated blade forces and need to be accounted for by the aerodynamic modelling approach. Aeroelastic simulations are carried out using the high fidelity multi body

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

    OpenAIRE

    Jie Zhu; Rongrong Gu; Pan Pan; Xin Cai

    2013-01-01

    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 ...

  15. AERODYNAMIC OPTIMIZATION FOR TURBINE BLADE BASED ON HIERARCHICAL FAIR COMPETITION GENETIC ALGORITHMS WITH DYNAMIC NICHE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A global optimization approach to turbine blade design based on hierarchical fair competition genetic algorithms with dynamic niche (HFCDN-GAs) coupled with Reynolds-averaged Navier-Stokes (RANS) equation is presented. In order to meet the search theory of GAs and the aerodynamic performances of turbine, Bezier curve is adopted to parameterize the turbine blade profile, and a fitness function pertaining to optimization is designed. The design variables are the control points' ordinates of characteristic polygon of Bezier curve representing the turbine blade profile. The object function is the maximum lift-drag ratio of the turbine blade. The constraint conditions take into account the leading and trailing edge metal angle, and the strength and aerodynamic performances of turbine blade. And the treatment method of the constraint conditions is the flexible penalty function. The convergence history of test function indicates that HFCDN-GAs can locate the global optimum within a few search steps and have high robustness. The lift-drag ratio of the optimized blade is 8.3% higher than that of the original one. The results show that the proposed global optimization approach is effective for turbine blade.

  16. Aerodynamic unsteady loads and vibrations of steam turbine L.P. blades

    International Nuclear Information System (INIS)

    In steam turbines, the aerodynamic sources of the blades vibrations for low pressure stages can induce a high stress level for some operating points. Therefore theoretical and experimental investigations are performed at E.D.F. They specially focus on the turbine rotor-stator interaction and the aerolastic rotor stability. A numerical method has been developed for predicting the aerodynamic damping of one cascade of profiles. The insteady flow calculation is based on the boundary element method, and is performed for the blade-to-blade surfaces. The results obtained on the first flexural mode for the L.P. blades of a 900 MW steam turbine, for several displacements and for several interblade phase angles, exhibits no instability of the rotor except low phase angles, but it is difficult to investigate these cases. The numerical results also support the relevance of the quasi-steady assumption. The same method has been used to calculate the rotor-stator interaction in the case of a potential flow. The main parameters are the gap between the two rows and the stator blade number/rotor blade number ratio (NR/NS). The results show that the dynamic loads strongly decrease with respect to the gap increase. Otherwise NR/NS = 2 (periodical pattern), which is a good approximation of the industrial value, provides slight unsteady loads on the rotor blades comparatively to other values

  17. Optimization of rotor blades for combined structural, dynamic, and aerodynamic properties

    Science.gov (United States)

    He, Cheng-Jian; Peters, David A.

    1990-01-01

    Optimal helicopter blade design with computer-based mathematical programming has received more and more attention in recent years. Most of the research has focused on optimum dynamic characteristics of rotor blades to reduce vehicle vibration. There is also work on optimization of aerodynamic performance and on composite structural design. This research has greatly increased our understanding of helicopter optimum design in each of these aspects. Helicopter design is an inherently multidisciplinary process involving strong interactions among various disciplines which can appropriately include aerodynamics; dynamics, both flight dynamics and structural dynamics; aeroelasticity: vibrations and stability; and even acoustics. Therefore, the helicopter design process must satisfy manifold requirements related to the aforementioned diverse disciplines. In our present work, we attempt to combine several of these important effects in a unified manner. First, we design a blade with optimum aerodynamic performance by proper layout of blade planform and spanwise twist. Second, the blade is designed to have natural frequencies that are placed away from integer multiples of the rotor speed for a good dynamic characteristics. Third, the structure is made as light as possible with sufficient rotational inertia to allow for autorotational landing, with safe stress margins and flight fatigue life at each cross-section, and with aeroelastical stability and low vibrations. Finally, a unified optimization refines the solution.

  18. Stochastic model for aerodynamic force dynamics on wind turbine blades in unsteady wind inflow

    CERN Document Server

    Luhur, Muhammad Ramzan; Kühn, Martin; Wächter, Matthias

    2015-01-01

    The paper presents a stochastic approach to estimate the aerodynamic forces with local dynamics on wind turbine blades in unsteady wind inflow. This is done by integrating a stochastic model of lift and drag dynamics for an airfoil into the aerodynamic simulation software AeroDyn. The model is added as an alternative to the static table lookup approach in blade element momentum (BEM) wake model used by AeroDyn. The stochastic forces are obtained for a rotor blade element using full field turbulence simulated wind data input and compared with the classical BEM and dynamic stall models for identical conditions. The comparison shows that the stochastic model generates additional extended dynamic response in terms of local force fluctuations. Further, the comparison of statistics between the classical BEM, dynamic stall and stochastic models' results in terms of their increment probability density functions gives consistent results.

  19. Integrated aerodynamic/dynamic/structural optimization of helicopter rotor blades using multilevel decomposition

    Science.gov (United States)

    Walsh, Joanne L.; Young, Katherine C.; Pritchard, Jocelyn I.; Adelman, Howard M.; Mantay, Wayne R.

    1995-01-01

    This paper describes an integrated aerodynamic/dynamic/structural (IADS) optimization procedure for helicopter rotor blades. The procedure combines performance, dynamics, and structural analyses with a general-purpose optimizer using multilevel decomposition techniques. At the upper level, the structure is defined in terms of global quantities (stiffness, mass, and average strains). At the lower level, the structure is defined in terms of local quantities (detailed dimensions of the blade structure and stresses). The IADS procedure provides an optimization technique that is compatible with industrial design practices in which the aerodynamic and dynamic designs are performed at a global level and the structural design is carried out at a detailed level with considerable dialog and compromise among the aerodynamic, dynamic, and structural groups. The IADS procedure is demonstrated for several examples.

  20. Multilevel decomposition approach to integrated aerodynamic/dynamic/structural optimization of helicopter rotor blades

    Science.gov (United States)

    Walsh, Joanne L.; Young, Katherine C.; Pritchard, Jocelyn I.; Adelman, Howard M.; Mantay, Wayne R.

    1994-01-01

    This paper describes an integrated aerodynamic, dynamic, and structural (IADS) optimization procedure for helicopter rotor blades. The procedure combines performance, dynamics, and structural analyses with a general purpose optimizer using multilevel decomposition techniques. At the upper level, the structure is defined in terms of local quantities (stiffnesses, mass, and average strains). At the lower level, the structure is defined in terms of local quantities (detailed dimensions of the blade structure and stresses). The IADS procedure provides an optimization technique that is compatible with industrial design practices in which the aerodynamic and dynamic design is performed at a global level and the structural design is carried out at a detailed level with considerable dialogue and compromise among the aerodynamic, dynamic, and structural groups. The IADS procedure is demonstrated for several cases.

  1. Aerodynamic pressure and flow-visualization measurement from a rotating wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Butterfield, C P

    1988-11-01

    Aerodynamic, load, flow-visualization, and inflow measurements have been made on a 10-m, three-bladed, downwind, horizontal-axis wind turbine (HAWT). A video camera mounted on the rotor was used to record nighttime and daytime video images of tufts attached to the low-pressure side of a constant-chord, zero-twist blade. Load measurements were made using strain gages mounted at every 10% of the blade's span. Pressure measurements were made at 80% of the blade's span. Pressure taps were located at 32 chordwise positions, revealing pressure distributions comparable with wind tunnel data. Inflow was measured using a vertical-plane array of eight propvane and five triaxial (U-V-W) prop-type anemometers located 10 m upwind in the predominant wind direction. One objective of this comprehensive research program was to study the effects of blade rotation on aerodynamic behavior below, near, and beyond stall. To this end, flow patterns are presented here that reveal the dynamic and steady behavior of flow conditions on the blade. Pressure distributions are compared to flow patterns and two-dimensional wind tunnel data. Separation boundary locations are shown that change as a function of spanwise location, pitch angle, and wind speed. 6 refs., 23 figs., 1 tab.

  2. Analysis of aerodynamic load on straight-bladed vertical axis wind turbine

    Science.gov (United States)

    Li, Qing'an; Maeda, Takao; Kamada, Yasunari; Murata, Junsuke; Kawabata, Toshiaki; Furukawa, Kazuma

    2014-08-01

    This paper presents a wind tunnel experiment for the evaluation of energy performance and aerodynamic forces acting on a small straight-bladed vertical axis wind turbine (VAWT) depending on several values of tip speed ratio. In the present study, the wind turbine is a four-bladed VAWT. The test airfoil of blade is symmetry airfoil (NACA0021) with 32 pressure ports used for the pressure measurements on blade surface. Based on the pressure distributions which are acted on the surface of rotor blade measured during rotation by multiport pressure-scanner mounted on a hub, the power, tangential force, lift and drag coefficients which are obtained by pressure distribution are discussed as a function of azimuthally position. And then, the loads which are applied to the entire wind turbine are compared with the experiment data of pressure distribution. As a result, it is clarified that aerodynamic forces take maximum value when the blade is moving to upstream side, and become small and smooth at downstream side. The power and torque coefficients which are based on the pressure distribution are larger than that by torque meter.

  3. 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.

  4. Aerodynamic investigation of the tip section for titanium blade 54"

    Czech Academy of Sciences Publication Activity Database

    Luxa, Martin; Šimurda, David; Fořt, J.; Fürst, J.; Šafařík, P.; Synáč, J.; Rudas, B.

    Madrid: European Conference on Turbomachinery (ETC), 2015, s. 1-13. ISSN 2410-4833. [European Conference on Turbomachinery Fluid Dynamics and Thermodynamics /11./. Madrid (ES), 23.03.2015-27.03.2015] R&D Projects: GA TA ČR(CZ) TA03020277 Institutional support: RVO:61388998 Keywords : supersonic flow * tip section * long turbine blade * steam turbine Subject RIV: BK - Fluid Dynamics

  5. The role of free stream turbulence and blade surface conditions on the aerodynamic performance of wind turbine blades

    Science.gov (United States)

    Maldonado, Victor Hugo

    Wind turbines operate within the atmospheric boundary layer (ABL) which gives rise to turbulence among other flow phenomena. There are several factors that contribute to turbulent flow: The operation of wind turbines in two layers of the atmosphere, the surface layer and the mixed layer. These layers often have unstable wind conditions due to the daily heating and cooling of the atmosphere which creates turbulent thermals. In addition, wind turbines often operate in the wake of upstream turbines such as in wind farms; where turbulence generated by the rotor can be compounded if the turbines are not sited properly. Although turbulent flow conditions are known to affect performance, i.e. power output and lifespan of the turbine, the flow mechanisms by which atmospheric turbulence and other external conditions (such as blade debris contamination) adversely impact wind turbines are not known in enough detail to address these issues. The main objectives of the current investigation are thus two-fold: (i) to understand the interaction of the turbulent integral length scales and surface roughness on the blade and its effect on aerodynamic performance, and (ii) to develop and apply flow control (both passive and active) techniques to alleviate some of the adverse fluid dynamics phenomena caused by the atmosphere (i.e. blade contamination) and restore some of the aerodynamic performance loss. In order to satisfy the objectives of the investigation, a 2-D blade model based on the S809 airfoil for horizontal axis wind turbine (HAWT) applications was manufactured and tested at the Johns Hopkins University Corrsin Stanley Wind Tunnel facility. Additional levels of free stream turbulence with an intensity of 6.14% and integral length scale of about 0.321 m was introduced into the flow via an active grid. The free stream velocity was 10 m/s resulting in a Reynolds number based on blade chord of Rec ≃ 2.08x105. Debris contamination on the blade was modeled as surface roughness

  6. 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.

  7. Aerodynamic design optimization of helicopter rotor blades including airfoil shape for hover performance

    Institute of Scientific and Technical Information of China (English)

    Ngoc Anh Vu; Jae Woo Lee; Jung Il Shu

    2013-01-01

    This study proposes a process to obtain an optimal helicopter rotor blade shape for aerodynamic performance in hover flight.A new geometry representation algorithm which uses the class function/shape function transformation (CST) is employed to generate airfoil coordinates.With this approach,airfoil shape is considered in terms of design variables.The optimization process is constructed by integrating several programs developed by author.The design variables include twist,taper ratio,point of taper initiation,blade root chord,and coefficients of the airfoil distribution function.Aerodynamic constraints consist of limits on power available in hover and forward flight.The trim condition must be attainable.This paper considers rotor blade configuration for the hover flight condition only,so that the required power in hover is chosen as the objective function of the optimization problem.Sensitivity analysis of each design variable shows that airfoil shape has an important role in rotor performance.The optimum rotor blade reduces the required hover power by 7.4% and increases the figure of merit by 6.5%,which is a good improvement for rotor blade design.

  8. Prediction of dynamic and aerodynamic characteristics of the centrifugal fan with forward curved blades

    Science.gov (United States)

    Polanský, Jiří; Kalmár, László; Gášpár, Roman

    2013-12-01

    The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic "A" variant contains 12 blades. The geometry of second "B" variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant "C" contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.

  9. 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.

  10. Analysis and Improvement of Aerodynamic Performance of Straight Bladed Vertical Axis Wind Turbines

    Science.gov (United States)

    Ahmadi-Baloutaki, Mojtaba

    Vertical axis wind turbines (VAWTs) with straight blades are attractive for their relatively simple structure and aerodynamic performance. Their commercialization, however, still encounters many challenges. A series of studies were conducted in the current research to improve the VAWTs design and enhance their aerodynamic performance. First, an efficient design methodology built on an existing analytical approach is presented to formulate the design parameters influencing a straight bladed-VAWT (SB-VAWT) aerodynamic performance and determine the optimal range of these parameters for prototype construction. This work was followed by a series of studies to collectively investigate the role of external turbulence on the SB-VAWTs operation. The external free-stream turbulence is known as one of the most important factors influencing VAWTs since this type of turbines is mainly considered for urban applications where the wind turbulence is of great significance. Initially, two sets of wind tunnel testing were conducted to study the variation of aerodynamic performance of a SB-VAWT's blade under turbulent flows, in two major stationary configurations, namely two- and three-dimensional flows. Turbulent flows generated in the wind tunnel were quasi-isotropic having uniform mean flow profiles, free of any wind shear effects. Aerodynamic force measurements demonstrated that the free-stream turbulence improves the blade aerodynamic performance in stall and post-stall regions by delaying the stall and increasing the lift-to-drag ratio. After these studies, a SB-VAWT model was tested in the wind tunnel under the same type of turbulent flows. The turbine power output was substantially increased in the presence of the grid turbulence at the same wind speeds, while the increase in turbine power coefficient due to the effect of grid turbulence was small at the same tip speed ratios. The final section presents an experimental study on the aerodynamic interaction of VAWTs in arrays

  11. Effect of Geometric Uncertainties on the Aerodynamic Characteristic of Offshore Wind Turbine Blades

    International Nuclear Information System (INIS)

    Offshore wind turbines operate in a complex unsteady flow environment which causes unsteady aerodynamic loads. The unsteady flow environment is characterized by a high degree of uncertainty. In addition, geometry variations and material imperfections also cause uncertainties in the design process. Probabilistic design methods consider these uncertainties in order to reach acceptable reliability and safety levels for offshore wind turbines. Variations of the rotor blade geometry influence the aerodynamic loads which also affect the reliability of other wind turbine components. Therefore, the present paper is dealing with geometric uncertainties of the rotor blades. These can arise from manufacturing tolerances and operational wear of the blades. First, the effect of geometry variations of wind turbine airfoils on the lift and drag coefficients are investigated using a Latin hypercube sampling. Then, the resulting effects on the performance and the blade loads of an offshore wind turbine are analyzed. The variations of the airfoil geometry lead to a significant scatter of the lift and drag coefficients which also affects the damage-equivalent flapwise bending moments. In contrast to that, the effects on the power and the annual energy production are almost negligible with regard to the assumptions made

  12. Aerodynamics tests of a transonic turbine blade cascade model consisting of low number of blades

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Šafařík, Pavel; Synáč, J.

    Plzeň: Západočeská univerzita Plzeň, 2012, s. 1-10. [Turbostroje 2012. Plzeň (CZ), 26.09.2012-27.09.2012] R&D Projects: GA ČR(CZ) GAP101/10/1329 Institutional support: RVO:61388998 Keywords : transonic flow * flow field periodicity * turbine blade cascade Subject RIV: BK - Fluid Dynamics

  13. Experimental and Numerical Study of the Aerodynamic Characteristics of an Archimedes Spiral Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Kyung Chun Kim

    2014-11-01

    Full Text Available A new type of horizontal axis wind turbine adopting the Archimedes spiral blade is introduced for urban-use. Based on the angular momentum conservation law, the design formula for the blade was derived using a variety of shape factors. The aerodynamic characteristics and performance of the designed Archimedes wind turbine were examined using computational fluid dynamics (CFD simulations. The CFD simulations showed that the new type of wind turbine produced a power coefficient (Cp of approximately 0.25, which is relatively high compared to other types of urban-usage wind turbines. To validate the CFD results, experimental studies were carried out using a scaled-down model. The instantaneous velocity fields were measured using the two-dimensional particle image velocimetry (PIV method in the near field of the blade. The PIV measurements revealed the presence of dominant vortical structures downstream the hub and near the blade tip. The interaction between the wake flow at the rotor downstream and the induced velocity due to the tip vortices were strongly affected by the wind speed and resulting rotational speed of the blade. The mean velocity profiles were compared with those predicted by the steady state and unsteady state CFD simulations. The unsteady CFD simulation agreed better with those of the PIV experiments than the steady state CFD simulations.

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

    Science.gov (United States)

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

    2015-11-01

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

  15. Aerodynamic Data for Two Variants of Root Turbine Blade Sections for A 54" Turbine Rotor Blade

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Šafařík, P.; Synáč, J.; Rudas, B.

    Düsseldorf: ASME, 2014, V02CT38A007-V02CT38A019. (2C). ISBN 978-0-7918-4562-2. [ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. Düsseldorf (DE), 16.06.2014-20.06.2014] R&D Projects: GA TA ČR(CZ) TA03020277; GA ČR(CZ) GAP101/10/1329 Institutional support: RVO:61388998 Keywords : steam turbine * rotor * blade cascade * root section Subject RIV: BK - Fluid Dynamics

  16. Aerodynamic Performance Enhancement of a Finite Span Wind Turbine Blade using Synthetic Jets

    Science.gov (United States)

    Taylor, Keith; Leong, Chia Min; Amitay, Michael

    2011-11-01

    Modern wind turbines undergo significant changes in pitch angle and structural loading through a revolution. Recent developments in flow control techniques, coupled with increased interest in green energy technologies, have led to interest in applying these techniques to wind turbines, in an effort to increase power output and reduce structural stress associated with widely varying loading. This reduction in structural stress could lead to reduced operational costs associated with the maintenance cycle. The effect of active flow control on the aerodynamic and structural aspects of finite span blade was investigated experimentally. When synthetic jets were employed the effect on aerodynamic performance and structural vibrations, during static and dynamic pitch conditions, was significant. In order to investigate if the jets can be actuated for less time (reduce their power consumption), they were actuated during only a portion of the pitch cycle or using pulse modulation. The results showed that these techniques result in significant reduction in the hysteresis loop and the structural vibrations.

  17. Aerodynamic models for Darrieus-type straight-bladed vertical axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Mazharul; Ting, David S.-K.; Fartaj, Amir [Department of Mechanical, Automotive and Materials Engineering, University of Windsor, Windsor, Ont. (Canada)

    2008-05-15

    Since ancient past humans have attempted to harness the wind energy through diversified means and vertical axis wind turbines (VAWTs) were one of the major equipment to achieve that. In this modern time, there is resurgence of interests regarding VAWTs as numerous universities and research institutions have carried out extensive research activities and developed numerous designs based on several aerodynamic computational models. These models are crucial for deducing optimum design parameters and also for predicting the performance before fabricating the VAWT. In this review, the authors have attempted to compile the main aerodynamic models that have been used for performance prediction and design of straight-bladed Darrieus-type VAWT. It has been found out that at present the most widely used models are the double-multiple streamtube model, Vortex model and the Cascade model. Each of these three models has its strengths and weaknesses which are discussed in this paper. (author)

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

    Science.gov (United States)

    Ge, Mingwei; Fang, Le; Tian, De

    2015-01-01

    At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project. PMID:26528815

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

    Science.gov (United States)

    Ge, Mingwei; Fang, Le; Tian, De

    2015-01-01

    At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-objective optimization are involved: one is based on the maximum power coefficient (CPopt) and the ultimate load, and the other is based on the ultimate load and the annual energy production (AEP). It is found that under the same configuration, the optimal design has a larger CPopt or AEP (CPopt//AEP) for the same ultimate load, or a smaller load for the same CPopt//AEP at higher Reynolds number. At a certain tip-speed ratio or ultimate load, the blade operating at higher Reynolds number should have a larger chord length and twist angle for the maximum Cpopt//AEP. If a wind turbine blade is designed by using an airfoil database with a mismatched Reynolds number from the actual one, both the load and Cpopt//AEP will be incorrectly estimated to some extent. In some cases, the assessment error attributed to Reynolds number is quite significant, which may bring unexpected risks to the earnings and safety of a wind power project. PMID:26528815

  20. Calibrated Blade-Element/Momentum Theory Aerodynamic Model of the MARIN Stock Wind Turbine: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Goupee, A.; Kimball, R.; de Ridder, E. J.; Helder, J.; Robertson, A.; Jonkman, J.

    2015-04-02

    In this paper, a calibrated blade-element/momentum theory aerodynamic model of the MARIN stock wind turbine is developed and documented. The model is created using open-source software and calibrated to closely emulate experimental data obtained by the DeepCwind Consortium using a genetic algorithm optimization routine. The provided model will be useful for those interested in validating interested in validating floating wind turbine numerical simulators that rely on experiments utilizing the MARIN stock wind turbine—for example, the International Energy Agency Wind Task 30’s Offshore Code Comparison Collaboration Continued, with Correlation project.

  1. Combined experimental and numerical investigations on the roughness effects on the aerodynamic performances of LPT blades

    Science.gov (United States)

    Berrino, Marco; Bigoni, Fabio; Simoni, Daniele; Giovannini, Matteo; Marconcini, Michele; Pacciani, Roberto; Bertini, Francesco

    2016-02-01

    The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels (Ra) for steady and unsteady inflows. Results from CFD simulations and experiments are presented for two different Reynolds numbers (300000 and 70000 representative of take-off and cruise conditions, respectively) in order to evaluate the roughness effects for two typical operating conditions. Computational fluid dynamics has been used to support and interpret experimental results, analyzing in detail the flow field on the blade surface and evaluating the non-dimensional local roughness parameters, further contributing to understand how and where roughness have some influence on the aerodynamic performance of the blade. The total pressure distributions in the wake region have been measured by means of a five-hole miniaturized pressure probe for the different flow conditions, allowing the evaluation of profile losses and of their dependence on the surface finish, as well as a direct comparison with the simulations. Results reported in the paper clearly highlight that only at the highest Reynolds number tested (Re=300000) surface roughness have some influence on the blade performance, both for steady and unsteady incoming flows. In this flow condition profile losses grow as the surface roughness increases, while no appreciable variations have been found at the lowest Reynolds number. The boundary layer evolution and the wake structure have shown that this trend is due to a thickening of the suction side boundary layer associated to an anticipation of transition process. On the other side, no effects have been observed on the pressure side boundary layer.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-15

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

  3. An experimental examination of the effect of trailing edge injection on the aerodynamic performance of gas turbine blades

    OpenAIRE

    Singer, Richard Tompkins, Jr.

    1988-01-01

    This thesis documents an experimental investigation into the effect of trailing edge Injection on the aerodynamic performance of turbine blades conducted at Virginia Polytechnic Institute and State University (VPl&SU). A brief description of the arrangement, instrumentation and data acquisition system of the VPl&SU Transonic Cascade Wind Tunnel is given. Testing was conducted under a number of test conditions. Baseline data was obtained for the blades with no trailing edge inje...

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

    Science.gov (United States)

    Wang, Xin

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

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

    Science.gov (United States)

    Lind, Andrew H.; Jones, Anya R.

    2016-07-01

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

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

    Directory of Open Access Journals (Sweden)

    Moutaz Elgammi

    2016-06-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  8. Experimental Investigation on the Ice Accretion Effects of Airplane Compressor Cascade of Stator Blades on the Aerodynamic Coefficients

    Directory of Open Access Journals (Sweden)

    M Ramezanizadeh

    2013-01-01

    Full Text Available In this paper the effects of ice accretion on the pressure distribution and the aerodynamic coefficients in a cascade of stator blades were experimentally investigated. Experiments were conducted on stage 67A type stator Controlled-Diffusion blades, which represent the mid-span of the first stage of the stator for a high-bypass turbofan engine. The measurements were carried out over a range of cascade angle of attack from 20° to 45° at Reynolds number of 500000. Experimental blade surface pressure coefficient distribution, lift and drag force coefficients, and momentum coefficients for clean blades were compared with those of the iced blades and the effects of ice accretion on these parameters were discussed. It is observed that the ice accretion on the blades causes the formation of flow bubble on the pressure side, downstream of the leading edge. By increasing the angle of attack from 20° to 35° , the bubble length decreases and the pressure coefficient increases inside the bubble region, constantly. In addition, for the iced blades the diffusion points at the suction side come closer to the trailing edge. In addition, it is found that by increasing the angle of attack up to 35° , the ice accretion has no significant effect on the lift coefficient but the drag coefficient increases comparing with the clean blades. More over at 40° and 45° , by increasing the flow interference effects between the blades, the iced blades experience higher lift and lower drag in comparison with the clean ones.

  9. Aerodynamics at off Design Performance of Root Section of Rotor Blade Last Stage of Large Output Steam Turbine

    Czech Academy of Sciences Publication Activity Database

    Luxa, Martin; Synáč, J.; Šafařík, P.; Šimurda, D.

    Plzeň: klub ASI-TURBOSTROJE Plzeň, 2007, s. 1-8. [Parní turbíny a jiné turbostroje 2007. Plzeň (CZ), 06.09.2007-07.09.2007] R&D Projects: GA ČR(CZ) GA101/05/2536 Institutional research plan: CEZ:AV0Z20760514 Keywords : steam turbine * aerodynamics * rotor blade Subject RIV: BK - Fluid Dynamics

  10. Vibration Suppression of a Helicopter Fuselage by Pendulum Absorbers : Rigid-Body Blades with Aerodynamic Excitation Force

    Science.gov (United States)

    Nagasaka, Imao; Ishida, Yukio; Koyama, Takayuki; Fujimatsu, Naoki

    Currently, some kinds of helicopters use pendulum absorbers in order to reduce vibrations. Present pendulum absorbers are designed based on the antiresonance concept used in the linear theory. However, since the vibration amplitudes of the pendulum are not small, it is considered that the nonlinearity has influence on the vibration characteristics. Therefore, the best suppression cannot be attained by using the linear theory. In a helicopter, periodic forces act on the blades due to the influences of the air thrust. These periodic forces act on the blades with the frequency which is the integer multiple of the rotational speed of the rotor. Our previous study proposed a 2-degree-of-freedom (2DOF) model composed of a rotor blade and a pendulum absorber. The blade was considered as a rigid body and it was excited by giving a sinusoidal deflection at its end. The present paper proposes a 3DOF model that is more similar to the real helicopter, since the freedom of the fuselage is added and the periodic forces are applied to the blade by aerodynamic force. The vibration is analyzed considering the nonlinear characteristics. The resonance curves of rotor blades with pendulum absorbers are obtained analytically and experimentally. It is clarified that the most efficient condition is obtained when the natural frequency of the pendulum is a little bit different from the frequency of the external force. Various unique nonlinear characteristics, such as bifurcations, are also shown.

  11. Parametric study on off-design aerodynamic performance of a horizontal axis wind turbine blade and proposed pitch control

    International Nuclear Information System (INIS)

    Highlights: • A pitch controlled 200 kW HAWT blade is designed with BEM for off-design conditions. • Parametric study conducted on power coefficient, axial and angular induction factors. • The optimal pitch angles were determined at off-design operating conditions. - Abstract: In this paper, a 200 kW horizontal axis wind turbine (HAWT) blade is designed using an efficient iterative algorithm based on the blade element momentum theory (BEM) on aerodynamic of wind turbines. The effects of off-design variations of wind speed are investigated on the blade performance parameters according to constant rotational speed of the rotor. The performance parameters considered are power coefficient, axial and angular induction factors, lift and drag coefficients on the blade, angle of attack and angle of relative wind. At higher or lower wind speeds than the designed rated speed, the power coefficient is reduced due to considerable changes in the angle of attacks. Therefore, proper pitch control angles were calculated to extract maximum possible power at various off-design speeds. The results showed a considerable improvement in power coefficient for the pitch controlled blade as compared with the baseline design in whole operating range. The present approach can be equally employed for determining pitch angles to design pitch control system of medium and large-scale wind turbines

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

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

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

  13. The optimisation and analysis of a centrifugal slurry pump impeller with 2 blades

    OpenAIRE

    Mehmet Salih Cellek; Tahsin Engin

    2013-01-01

    With FLUENT, which is Computational Fluid Dynamics (CFD) software, it becomes possible to define the performance of complicated flow in turbo machines like pumps and blowers. It is not only reduced costs but also saves time. This study is aimed to optimize a commercial slurry pump impeller. Therefore, four different types of impellers were designed with using various blade angles, blade length and splitter blade on the impeller, which is the most crucial component of the pump. As a result of ...

  14. EXPERIMENTAL RESEARCH ON AERODYNAMIC PERFORMANCE AND EXIT FLOW FIELD OF LOW PRESSURE AXIAL FLOW FAN WITH CIRCUMFERENTIAL SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The aerodynamic performance of the rotors was measured. At the design condition at outlet of the rotors, detailed flow measurements were performed with a five-hole probe and a Hot-Wire Anemometer (HWA). The results show that compared to the radial rotor, the forward-skewed rotor demonstrates a wider Stable Operating Range (SOR), is able to reduce the total pressure loss in the hub region and make main loading of blade accumulating in the mid-span region. There is a wider wake in the upper mid-span region of the forward-skewed rotor. Compared to the radial rotor, in the backward-skewed rotor there is higher total pressure loss near the hub and shroud regions and lower loss in the mid-span region. In addition, the velocity deficit in the wake is lower at mid-span of the backward-skewed rotor than the forward-skewed rotor.

  15. SIROCCO. Silent rotors by acoustic optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Schepers, J.G.; Curvers, A. [ECN Wind Energy, Petten (Netherlands); Oerlemans, S. [National Aerospace Laboratory NLR, Amsterdam (Netherlands); Braun, K.; Lutz, T.; Herrig, A.; Wuerz, W. [University of Stuttgart, Stuttgart (Germany); Matesanz, A.; Garcillan, L. [Gamesa Eolica, Madrid (Spain); Fisher, M.; Koegler, K.; Maeder, T. [GE Wind Energy/GE Global Research (United States)

    2007-07-15

    In this paper the results from the European 5th Framework project 'SIROCCO' are described. The project started in January 2003 and will end in August 2007. The main aim of the SIROCCO project is to reduce wind-turbine aerodynamic noise significantly while maintaining the aerodynamic performance. This is achieved by designing new acoustically and aerodynamically optimised airfoils for the outer part of the blade. The project focussed primarily on reducing trailing edge noise, which was broadly believed to be the dominant noise mechanism of modern wind turbines.

  16. The optimisation and analysis of a centrifugal slurry pump impeller with 2 blades

    Directory of Open Access Journals (Sweden)

    Mehmet Salih Cellek

    2013-08-01

    Full Text Available With FLUENT, which is Computational Fluid Dynamics (CFD software, it becomes possible to define the performance of complicated flow in turbo machines like pumps and blowers. It is not only reduced costs but also saves time. This study is aimed to optimize a commercial slurry pump impeller. Therefore, four different types of impellers were designed with using various blade angles, blade length and splitter blade on the impeller, which is the most crucial component of the pump. As a result of analysis it was seen that every impeller affected on the pump performance at different flow rate.

  17. Evaluation of Rotor Structural and Aerodynamic Loads using Measured Blade Properties

    Science.gov (United States)

    Jung, Sung N.; You, Young-Hyun; Lau, Benton H.; Johnson, Wayne; Lim, Joon W.

    2012-01-01

    The structural properties of Higher harmonic Aeroacoustic Rotor Test (HART I) blades have been measured using the original set of blades tested in the wind tunnel in 1994. A comprehensive rotor dynamics analysis is performed to address the effect of the measured blade properties on airloads, blade motions, and structural loads of the rotor. The measurements include bending and torsion stiffness, geometric offsets, and mass and inertia properties of the blade. The measured properties are correlated against the estimated values obtained initially by the manufacturer of the blades. The previously estimated blade properties showed consistently higher stiffnesses, up to 30% for the flap bending in the blade inboard root section. The measured offset between the center of gravity and the elastic axis is larger by about 5% chord length, as compared with the estimated value. The comprehensive rotor dynamics analysis was carried out using the measured blade property set for HART I rotor with and without HHC (Higher Harmonic Control) pitch inputs. A significant improvement on blade motions and structural loads is obtained with the measured blade properties.

  18. 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.

  19. Optimization methods applied to the aerodynamic design of helicopter rotor blades

    Science.gov (United States)

    Walsh, Joanne L.; Bingham, Gene J.; Riley, Michael F.

    1987-01-01

    Described is a formal optimization procedure for helicopter rotor blade design which minimizes hover horsepower while assuring satisfactory forward flight performance. The approach is to couple hover and forward flight analysis programs with a general-purpose optimization procedure. The resulting optimization system provides a systematic evaluation of the rotor blade design variables and their interaction, thus reducing the time and cost of designing advanced rotor blades. The paper discusses the basis for and details of the overall procedure, describes the generation of advanced blade designs for representative Army helicopters, and compares design and design effort with those from the conventional approach which is based on parametric studies and extensive cross-plots.

  20. Characteristics of Aerodynamic and Noise for Tubular Centrifugal Fan (2nd report) : Effects of Belt Case, Inclination of Blade, Size of Casing and Preventive Plate against Reverse Flow

    OpenAIRE

    Kodama, Yoshio; Futigami, Shinichirou; Hayashi, Hidechito; Mimura, Yujirou

    1999-01-01

    The effects of the belt case, the inclination of blade, the size of casing and the preventive plate of a tubular centrifugal fan on both fan noise and the aerodynamic characteristics are experimentally investigated by using three impellers. The results are summarized as follows : A considerable amount of a rise of pressure and fan efficiency can be expected by using the inclined blade and taking off belt case. Therefore, the specific noise level of the tubular centrifugal fan decrease conside...

  1. Stochastic Modeling of Lift and Drag Dynamics to Obtain Aerodynamic Forces with Local Dynamics on Rotor Blade under Unsteady Wind Inflow

    OpenAIRE

    Muhammad Ramzan Luhur; Joachim Peinke; Matthias Waechter

    2014-01-01

    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 comparis...

  2. 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...

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

    Science.gov (United States)

    Flegel, Ashlie B.

    2014-01-01

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

  4. Measurements of the Aerodynamic Normal Forces on a 12-kW Straight-Bladed Vertical Axis Wind Turbine

    Directory of Open Access Journals (Sweden)

    Eduard Dyachuk

    2015-08-01

    Full Text Available The knowledge of unsteady forces is necessary when designing vertical axis wind turbines (VAWTs. Measurement data for turbines operating at an open site are still very limited. The data obtained from wind tunnels or towing tanks can be used, but have limited applicability when designing large-scale VAWTs. This study presents experimental data on the normal forces of a 12-kW straight-bladed VAWT operated at an open site north of Uppsala, Sweden. The normal forces are measured with four single-axis load cells. The data are obtained for a wide range of tip speed ratios: from 1.7 to 4.6. The behavior of the normal forces is analyzed. The presented data can be used in validations of aerodynamic models and the mechanical design for VAWTs.

  5. Aerodynamic Data for Tip Section of Rotor with 52 Titanium Blades 1375 mm Long

    Czech Academy of Sciences Publication Activity Database

    Luxa, Martin; Synáč, J.; Šimurda, David; Šafařík, Pavel

    Plzeň: ZČU Plzeň, 2014. ISBN 978-80-260-6447-3. [Turbostroje 2014. Plzeň (CZ), 24.09.2014-25.09.2014] R&D Projects: GA TA ČR(CZ) TA03020277 Institutional support: RVO:61388998 Keywords : supersonic flow * long turbine rotor blade * tip section Subject RIV: BK - Fluid Dynamics

  6. Aerodynamic stiffness of an unbound eccentric whirling centrifugal impeller with an infinite number of blades

    Science.gov (United States)

    Allaire, P. E.; Branagan, L. A.; Kocur, J. A.

    1982-01-01

    An unbounded eccentric centrifugal impeller with an infinite number of log spiral blades undergoing synchronous whirling in an incompressible fluid is considered. The forces acting on it due to coriolis forces, centripetal forces, changes in linear momentum, changes in pressure due to rotating and changes in pressure due to changes in linear momentum are evaluated.

  7. Aerodynamic analysis of potential use of flow control devices on helicopter rotor blades

    Science.gov (United States)

    Tejero, F.; Doerffer, P.; Szulc, O.

    2014-08-01

    The interest in the application of flow control devices has been rising in the last years. Recently, several passive streamwise vortex generators have been analysed in a configuration of a curved wall nozzle within the framework of the UFAST project (Unsteady Effects of Shock Wave Induced Separation, 2005 - 2009). Experimental and numerical results proved that the technology is effective in delaying flow separation. The numerical investigation has been extended to helicopter rotor blades in hover and forward flight applying the FLOWer solver (RANS approach) implementing the chimera overlapping grids technique and high performance computing. CFD results for hover conditions confirm that the proposed passive control method reduces the flow separation increasing the thrust over power consumption. The paper presents the numerical validation for both states of flight and the possible implementation of RVGs on helicopter rotor blades.

  8. Aerodynamic analysis of potential use of flow control devices on helicopter rotor blades

    International Nuclear Information System (INIS)

    The interest in the application of flow control devices has been rising in the last years. Recently, several passive streamwise vortex generators have been analysed in a configuration of a curved wall nozzle within the framework of the UFAST project (Unsteady Effects of Shock Wave Induced Separation, 2005 – 2009). Experimental and numerical results proved that the technology is effective in delaying flow separation. The numerical investigation has been extended to helicopter rotor blades in hover and forward flight applying the FLOWer solver (RANS approach) implementing the chimera overlapping grids technique and high performance computing. CFD results for hover conditions confirm that the proposed passive control method reduces the flow separation increasing the thrust over power consumption. The paper presents the numerical validation for both states of flight and the possible implementation of RVGs on helicopter rotor blades.

  9. Aerodynamic Research on the Tip Sections of a Long Turbine Blade

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Synáč, J.; Šafařík, Pavel

    Berlín: ASME, 2008, s. 1-8. ISBN 0-7918-3824-2. [ASME Turbo Expo 2008. Berlin (DE), 09.06.2008-13.06.2008] R&D Projects: GA ČR GA101/07/1508; GA MŠk(CZ) ME08025 Institutional research plan: CEZ:AV0Z20760514 Keywords : transsonic flow * tip blade section * turbomachinery Subject RIV: BK - Fluid Dynamics http://www.asmeconferences.org/TE08/

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

    Science.gov (United States)

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

    1981-01-01

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

  11. A practical study of the aerodynamic impact of wind turbine blade leading edge erosion

    International Nuclear Information System (INIS)

    During operation wind turbine blades are exposed to a wide variety of atmospheric and environmental conditions; inspection reports for blades that have been operating for several years show varying degrees of leading edge erosion. It is important to be able to estimate the impact of different stages of erosion on wind turbine performance, but this is very difficult even with advanced CFD models. In this study, wind tunnel testing was used to evaluate a range of complex erosion stages. Erosion patterns were transferred to thin films that were applied to 18% thick commercial wind turbine aerofoils and full lift and drag polars were measured in a wind tunnel. Tests were conducted up to a Reynolds number of 2.20 × 106 scaling based on the local roughness Reynolds number was used in combination with different film thicknesses to simulate a variety of erosion depths. The results will be very useful for conducting cost/benefit analyses of different methods of blade protection and repair, as well as for defining the appropriate timescales for these processes

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

    Science.gov (United States)

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

    1979-01-01

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

  13. Stochastic modeling of lift and drag dynamics to obtain aerodynamic forces with local dynamics on rotor blade under unsteady wind inflow

    International Nuclear Information System (INIS)

    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. (author)

  14. 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

  15. Aerodynamic and Structural Design of MultiMW Wind Turbine Blades beyond 5MW

    Science.gov (United States)

    Hillmer, B.; Borstelmann, T.; Schaffarczyk, P. A.; Dannenberg, L.

    2007-07-01

    A unified approach was taken to the design of wind-turbine blades for multiMW machines up to 10 MW. Using input from standard existing machines, three baseline versions were designed. Then - after up-scaling - using the aero-elastic code FLEX5 a typical extreme load case was selected. As a result, weights seem to increase more than might be expected by an empirical law deduced from statistical data. However, some further investigations are needed, e. g. buckling and fatigue analyses. The authors regard the method developed here as a useful approach for pre-design investigation. One important aspect seems to be the need for high-quality GRPs, with admissible strength of more than 120 MPa.

  16. Aerodynamic and Structural Design of MultiMW Wind Turbine Blades beyond 5MW

    International Nuclear Information System (INIS)

    A unified approach was taken to the design of wind-turbine blades for multiMW machines up to 10 MW. Using input from standard existing machines, three baseline versions were designed. Then - after up-scaling - using the aero-elastic code FLEX5 a typical extreme load case was selected. As a result, weights seem to increase more than might be expected by an empirical law deduced from statistical data. However, some further investigations are needed, e. g. buckling and fatigue analyses. The authors regard the method developed here as a useful approach for pre-design investigation. One important aspect seems to be the need for high-quality GRPs, with admissible strength of more than 120 MPa

  17. CFD aerodynamic analysis of non-conventional airfoil sections for very large rotor blades

    International Nuclear Information System (INIS)

    The aerodynamic performance of flat-back and elliptically shaped airfoils is analyzed on the basis of CFD simulations. Incompressible and low-Mach preconditioned compressible unsteady simulations have been carried out using the k-w SST and the Spalart Allmaras turbulence models. Time averaged lift and drag coefficients are compared to wind tunnel data for the FB 3500-1750 flat back airfoil while amplitudes and frequencies are also recorded. Prior to separation averaged lift is well predicted while drag is overestimated keeping however the trend in the tests. The CFD models considered, predict separation with a 5° delay which is reflected on the load results. Similar results are provided for a modified NACA0035 with a rounded (elliptically shaped) trailing edge. Finally as regards the dynamic characteristics in the load signals, there is fair agreement in terms of Str number but significant differences in terms of lift and drag amplitudes

  18. Method for estimating the aerodynamic coefficients of wind turbine blades at high angles of attack

    Science.gov (United States)

    Beans, E. W.; Jakubowski, G. S.

    1983-12-01

    The method is based on the hypothesis that at high angles of attack the force on an airfoil is produced by the deflection of the fluid across the lower surface. It is also hypothesized that all airfoils behave the same regardless of shape and that the effects of circulation and skin friction are small. It is pointed out that the expression for the force N normal to the airfoil due to momentum exchange can be written in terms of the component parallel to the flow (drag) and the component perpendicular to the flow (lift). A comparison of estimated values with measured values and generally accepted data indicates that the method given here estimates coefficients which are low. It is thought that the difference may derive from the persistence of circulation at high angles of attack. Low estimates are not seen as a serious limitation to the designer of wind turbines. Owing to the fifth power diameter relation, the effect of a low estimate of performance on the inner portion of the blade is minimized.

  19. Optimisation of a stator blade using response surface method in a single-stage transonic axial compressor

    Energy Technology Data Exchange (ETDEWEB)

    Jang, C-M. [Korea Institute of Construction Technology, Daehwa-dong, Goyang-Si (Korea). Fire and Engineering Services Research Department; Kim, K-Y. [Inha University, Incheon (Korea). Department of Mechanical Engineering

    2005-12-15

    This article describes the shape optimization of a stator blade in a single-stage transonic axial compressor. The blade optimization has been performed using response surface method and three-dimensional Navier-Stokes analysis. Thin-layer approximation is introduced to the Navier-Stokes equations, and an explicit Runge-Kutta scheme is used to solve the governing equations. Two geometric design variables of the stator blade, which are used to define a stacking line, are introduced to increase an adiabatic efficiency. D-optimal design is employed to reduce the number of evaluation points for response surface. With the optimization of the stator blade, the adiabatic efficiency is successfully improved when compared with that of the reference shape of the stator with straight stacking line. Positive stacking line, which bends on blade pressure side, effectively suppresses the flow separation on the blade suction surface of the stator. (author)

  20. Shark skin inspired riblet structures as aerodynamically optimized high temperature coatings for blades of aeroengines

    International Nuclear Information System (INIS)

    This paper deals with different structuring methods for high temperature resistant nickel alloys. The ideal structured surface for a possible application on the blades of aeroengines combines high oxidation resistance with low drag in a hot gas flow. The effect of drag reduction due to riblet structured surfaces was originally inspired by shark scales, which have a drag reducing riblet structure. The necessary riblet sizes for effective drag reduction depend on the temperature, pressure and velocity of the flowing medium (gas or liquid). These riblet sizes were calculated for the different sections in an aeroengine. The riblets were successfully produced on a NiCoCrAlY coating by picosecond laser treatment. This method is suitable for larger structures within the range of some tens of micrometers. Furthermore, experiments were performed by depositing different materials through polymer and metal masks via electrodeposition and physical vapor deposition. All fabricated structures were oxidized at 900–1000 °C for up to 100 h to simulate the temperature conditions in an aeroengine. The resulting shape of the riblets was characterized using scanning electron microscopy. The most accurate structures were obtained by using photolithography with a subsequent electrodeposition of nickel. This method is suited for single digit micrometer structures. The reduction of the wall shear stress was measured in an oil channel. The riblet structures prior to oxidation showed a reduction of the wall shear stress of up to 4.9% compared to a normal smooth surface. This proves that the fabricated riblet design can be used as a drag reducing surface

  1. Wind Turbine Blade Design

    Directory of Open Access Journals (Sweden)

    Richard J. Crossley

    2012-09-01

    Full Text Available A detailed review of the current state-of-art for wind turbine blade design is presented, including theoretical maximum efficiency, propulsion, practical efficiency, HAWT blade design, and blade loads. The review provides a complete picture of wind turbine blade design and shows the dominance of modern turbines almost exclusive use of horizontal axis rotors. The aerodynamic design principles for a modern wind turbine blade are detailed, including blade plan shape/quantity, aerofoil selection and optimal attack angles. A detailed review of design loads on wind turbine blades is offered, describing aerodynamic, gravitational, centrifugal, gyroscopic and operational conditions.

  2. Wind Turbine Blade Design

    OpenAIRE

    Richard J. Crossley; Peter J. Schubel

    2012-01-01

    A detailed review of the current state-of-art for wind turbine blade design is presented, including theoretical maximum efficiency, propulsion, practical efficiency, HAWT blade design, and blade loads. The review provides a complete picture of wind turbine blade design and shows the dominance of modern turbines almost exclusive use of horizontal axis rotors. The aerodynamic design principles for a modern wind turbine blade are detailed, including blade plan shape/quantity, aerofoil selection ...

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

    Science.gov (United States)

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

    2013-01-01

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

  4. Ultimate Strength of Wind Turbine Blades under Multiaxial Loading

    OpenAIRE

    Haselbach, Philipp Ulrich; Branner, Kim; Berggreen, Christian; Bitsche, Robert

    2015-01-01

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

  5. Aerodynamic design and performance testing of an advanced 30 deg swept, eight bladed propeller at Mach numbers from 0. 2 to 0. 85. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Black, D.M.; Menthe, R.W.; Wainauski, H.S.

    1978-09-01

    The increased emphasis on fuel conservation in the world has stimulated a series of studies of both conventional and unconventional propulsion systems for commercial aircraft. Preliminary results from these studies indicate that a fuel saving of from 15 to 28 percent may be realized by the use of an advanced high speed turboprop. The turboprop must be capable of high efficiency at Mach 0.8 above 10.68 km (35,000 ft) altitude if it is to compete with turbofan powered commercial aircraft. An advanced turboprop concept was wind tunnel tested. The model included such concepts as an aerodynamically integrated propeller/nacelle, blade sweep and power (disk) loadings approximately three times higher than conventional propeller designs. The aerodynamic design for the model is discussed. Test results are presented which indicate propeller net efficiencies near 80 percent were obtained at high disk loadings at Mach 0.8.

  6. Aerodynamic design and performance testing of an advanced 30 deg swept, eight bladed propeller at Mach numbers from 0.2 to 0.85

    Science.gov (United States)

    Black, D. M.; Menthe, R. W.; Wainauski, H. S.

    1978-01-01

    The increased emphasis on fuel conservation in the world has stimulated a series of studies of both conventional and unconventional propulsion systems for commercial aircraft. Preliminary results from these studies indicate that a fuel saving of from 15 to 28 percent may be realized by the use of an advanced high speed turboprop. The turboprop must be capable of high efficiency at Mach 0.8 above 10.68 km (35,000 ft) altitude if it is to compete with turbofan powered commercial aircraft. An advanced turboprop concept was wind tunnel tested. The model included such concepts as an aerodynamically integrated propeller/nacelle, blade sweep and power (disk) loadings approximately three times higher than conventional propeller designs. The aerodynamic design for the model is discussed. Test results are presented which indicate propeller net efficiencies near 80 percent were obtained at high disk loadings at Mach 0.8.

  7. Methods for root effects, tip effects and extending the angle of attack range to {+-} 180 deg., with application to aerodynamics for blades on wind turbines and propellers

    Energy Technology Data Exchange (ETDEWEB)

    Montgomerie, Bjoern

    2004-06-01

    For wind turbine and propeller performance calculations aerodynamic data, valid for several radial stations along the blade, are used. For wind turbines the data must be valid for the 360 degree angle of attack range. The reason is that all kinds of abnormal conditions must be analysed especially during the design of the turbine. Frequently aerodynamic data are available from wind tunnel tests where the angle of attack range is from say -5 to +20 degrees. This report describes a method to extend such data to be valid for {+-} 180 degrees. Previously the extension of data has been very approximate following the whim of the moment with the analyst. Furthermore, the Himmelskamp effect at the root and tip effects are treated in the complete method.

  8. 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.

  9. Experimental Investigation of the Influence of Local Flow Features on the Aerodynamic Damping of an Oscillating Blade Row

    OpenAIRE

    Sanz Luengo, Antonio

    2014-01-01

    The general trend of efficiency increase, weight and noise reduction has derived in the design of more slender, loaded, and 3D shaped blades. This has a significant impact on the stability of fan, and low pressure turbine blades, which are more prone to aeroelastic phenomena such as flutter. The flutter phenomenon is a self-excited, self-sustained unstable vibration produced by the interaction of flow and structure. These working conditions will induce either blade overload, or High Cycle Fat...

  10. Investigation of the impact of rain and particle erosion on rotor blade aerodynamics with an erosion test facility to enhancing the rotor blade performance and durability

    International Nuclear Information System (INIS)

    During their operational life span of around 20 years, the individual components of a wind turbine, especially the rotor blades, are exposed to extreme environmental influences. This is the result of the continuous exposure of wind turbines to the elements and of particularly high rotor blade tip speeds, which exceed a velocity of 90 m/s. These effects result in leading edge erosion. Rotor blades are therefore protected by special coating systems, e.g. varnishes and foils. The durability of those surface coatings varies depending on the location of the wind turbine and often proves to be insufficient. Additionally, there is no standardised test procedure for the evaluation of the durability and protective effect of the coating materials under the highly erosive conditions at the location of the wind turbines. In the course of this project, we will develop a testing procedure to evaluate the erosion of coating materials on actual leading edges of rotor blades, which will be applied in a test facility. The test rig will be capable of simulating a realistic application of rain and sand to gauge the effects of erosion. During the application, two test objects can be tested simultaneously. The geometry of the test objects will be adapted to represent that of real rotor blade tips. In order to generate comparable and transferable results, several challenges have to be met during the implementation, especially the realistic reproduction of environmental influences and the corrosion damage mechanism. In this regard, the duration of the test procedure is very important because a time lapse factor of 100-260 is intended. An operation of 20 years can thereby be simulated within 4 to 10 weeks

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

    Energy Technology Data Exchange (ETDEWEB)

    Naughton, Jonathan W. [University of Wyoming

    2014-08-05

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

  12. Numerical simulation and validation of helicopter blade-vortex interaction using coupled CFD/CSD and three levels of aerodynamic modeling

    Science.gov (United States)

    Amiraux, Mathieu

    Rotorcraft Blade-Vortex Interaction (BVI) remains one of the most challenging flow phenomenon to simulate numerically. Over the past decade, the HART-II rotor test and its extensive experimental dataset has been a major database for validation of CFD codes. Its strong BVI signature, with high levels of intrusive noise and vibrations, makes it a difficult test for computational methods. The main challenge is to accurately capture and preserve the vortices which interact with the rotor, while predicting correct blade deformations and loading. This doctoral dissertation presents the application of a coupled CFD/CSD methodology to the problem of helicopter BVI and compares three levels of fidelity for aerodynamic modeling: a hybrid lifting-line/free-wake (wake coupling) method, with modified compressible unsteady model; a hybrid URANS/free-wake method; and a URANS-based wake capturing method, using multiple overset meshes to capture the entire flow field. To further increase numerical correlation, three helicopter fuselage models are implemented in the framework. The first is a high resolution 3D GPU panel code; the second is an immersed boundary based method, with 3D elliptic grid adaption; the last one uses a body-fitted, curvilinear fuselage mesh. The main contribution of this work is the implementation and systematic comparison of multiple numerical methods to perform BVI modeling. The trade-offs between solution accuracy and computational cost are highlighted for the different approaches. Various improvements have been made to each code to enhance physical fidelity, while advanced technologies, such as GPU computing, have been employed to increase efficiency. The resulting numerical setup covers all aspects of the simulation creating a truly multi-fidelity and multi-physics framework. Overall, the wake capturing approach showed the best BVI phasing correlation and good blade deflection predictions, with slightly under-predicted aerodynamic loading magnitudes

  13. Aerodynamic Investigations of Root Sections of Long Rotor Blades Applied at the Last Stages of Steam Turbines

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Šafařík, P.; Synáč, J.; Šťastný, M.

    Copenhagen: ASME, 2012, s. 955-964. [ASME Turbo Expo 2012. Copenhagen (DK), 11.06.2012-15.06.2012] R&D Projects: GA AV ČR(CZ) IAA200760801; GA ČR(CZ) GAP101/10/1329 Institutional support: RVO:61388998 Keywords : transonic flow * root section * turbine blade cascade Subject RIV: BK - Fluid Dynamics

  14. 具有较强气动性能的风力发电机叶片研究%Research on wind turbine blades with better aerodynamic performance

    Institute of Scientific and Technical Information of China (English)

    徐浩; 朱益红; 韩建景; 李永泉

    2012-01-01

    Using fluid analysis software Fluent, the flow field simulation of two common airfoil shape N ACA4415 and SD7043 was processed. The differences between the aerodynamic performances from the shape characteristics were analyzed. Using of the airfoil shape analysis software Profili, a new airfoil shape with good characteristics, which combine NACA4415 and SD7043, was designed,then new and original wing airfoil lift-to-drag characteristics in the difference were analyzed. The results show that the new airfoil has achieved better aerodynamic performance. Finally, a set of small wind turbine blades were designed by using the new shape.%利用流体分析软件Fluent对NACA4415与SD7043两种常见翼型进行流场模拟,从外形特征分析两者的气动性能差异,进一步利用翼型分析软件profili的翼型设计功能,结合两种翼型的长处,设计出新的翼型,并对新翼型与原有翼型在升阻特性上的差异进行分析,对比发现新翼型气动性能更优.最后利用新翼型基于Solidworks设计出一款小型风力发电机叶片.

  15. Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems. Task 4: Advanced fan section aerodynamic analysis

    Science.gov (United States)

    Crook, Andrew J.; Delaney, Robert A.

    1992-01-01

    The purpose of this study is the development of a three-dimensional Euler/Navier-Stokes flow analysis for fan section/engine geometries containing multiple blade rows and multiple spanwise flow splitters. An existing procedure developed by Dr. J. J. Adamczyk and associates and the NASA Lewis Research Center was modified to accept multiple spanwise splitter geometries and simulate engine core conditions. The procedure was also modified to allow coarse parallelization of the solution algorithm. This document is a final report outlining the development and techniques used in the procedure. The numerical solution is based upon a finite volume technique with a four stage Runge-Kutta time marching procedure. Numerical dissipation is used to gain solution stability but is reduced in viscous dominated flow regions. Local time stepping and implicit residual smoothing are used to increase the rate of convergence. Multiple blade row solutions are based upon the average-passage system of equations. The numerical solutions are performed on an H-type grid system, with meshes being generated by the system (TIGG3D) developed earlier under this contract. The grid generation scheme meets the average-passage requirement of maintaining a common axisymmetric mesh for each blade row grid. The analysis was run on several geometry configurations ranging from one to five blade rows and from one to four radial flow splitters. Pure internal flow solutions were obtained as well as solutions with flow about the cowl/nacelle and various engine core flow conditions. The efficiency of the solution procedure was shown to be the same as the original analysis.

  16. 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.

  17. Measurements of the Aerodynamic Normal Forces on a 12-kW Straight-Bladed Vertical Axis Wind Turbine

    OpenAIRE

    Eduard Dyachuk; Morgan Rossander; Anders Goude; Hans Bernhoff

    2015-01-01

    The knowledge of unsteady forces is necessary when designing vertical axis wind turbines (VAWTs). Measurement data for turbines operating at an open site are still very limited. The data obtained from wind tunnels or towing tanks can be used, but have limited applicability when designing large-scale VAWTs. This study presents experimental data on the normal forces of a 12-kW straight-bladed VAWT operated at an open site north of Uppsala, Sweden. The normal forces are measured with four single...

  18. Aerodynamics and Heat Transfer Studies of Parameters Specific to the IGCC-Requirements: Endwall Contouring, Leading Edge and Blade Tip Ejection under Rotating Turbine Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schobeiri, Meinhard; Han, Je-Chin

    2014-09-30

    This report deals with the specific aerodynamics and heat transfer problematic inherent to high pressure (HP) turbine sections of IGCC-gas turbines. Issues of primary relevance to a turbine stage operating in an IGCC-environment are: (1) decreasing the strength of the secondary flow vortices at the hub and tip regions to reduce (a), the secondary flow losses and (b), the potential for end wall deposition, erosion and corrosion due to secondary flow driven migration of gas flow particles to the hub and tip regions, (2) providing a robust film cooling technology at the hub and that sustains high cooling effectiveness less sensitive to deposition, (3) investigating the impact of blade tip geometry on film cooling effectiveness. The document includes numerical and experimental investigations of above issues. The experimental investigations were performed in the three-stage multi-purpose turbine research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University. For the numerical investigations a commercial Navier-Stokes solver was utilized.

  19. EFFECT OF UPSTREAM ROTOR ON AERODYNAMIC FORCE OF DOWNSTREAM STATOR BLADES%上游转子对下游静子叶片气动力的影响

    Institute of Scientific and Technical Information of China (English)

    王志强; 胡骏; 王英锋; 赵勇

    2006-01-01

    为研究轴流压气机下游静子叶片非定常气动力的大小和频率的变化规律,采用在静子叶片表面埋设微型动态压力传感器的方法,在低速单级轴流压气机实验器上进行了静子叶片表面压力的测量.测量了不同轴向间距、不同转速下从近堵塞到近失速的宽广流量范围,并对所测得的静子叶片非定常气动力进行了离散傅立叶变换,以分析其频谱特性.实验结果表明:在转子尾迹的影响下,静子叶片表面的波动频率是转子的尾迹频率及其倍频.转子尾迹频率的高频分量对静子叶片吸力面前缘的影响比对其他位置的影响大.叶片表面的非定常压力和气动力随压气机流量、转速和轴向间距的变化而变化.%To study the amplitude and the frequency of the aerodynamic force on stator blades, micro-sensors are embedded on the surface of stator blades of a low-speed single-stage axial compressor rig. The unsteady pressure distribution on stator blades is measured under the conditions of different axial spacing between the rotor and the stator, different rotating speeds and an extensive range of the mass flow. Amplitudes and frequencies of aerodynamic forces are analyzed by the Fourier transform. Experimental results show that under the effect of the rotor wake, the dominant frequencies of pressure fluctuations on stator blades are the rotor blade passing frequency (BPF) and its harmonics. The higher harmonics of the rotor BPF in the fore part of the suction side are more prominent than that in the other parts of the stator blade. Otherwise, fluctuations of the pressure and the aerodynamic force on stator blades vary with the mass flow, the rotating speed and the axial spacing between the rotor and the stator.

  20. Numerical simulation on the aerofoil aerodynamic performance of wind turbine blade%风力机叶片翼型气动性能数值模拟

    Institute of Scientific and Technical Information of China (English)

    胡丹梅; 李佳; 张志超

    2011-01-01

    采用数值模拟方法对NACA23012,NACA4412,S809,S810等4种常用风力机叶片翼型进行了研究,分析了翼型静止与振荡时的气动性能.随着攻角的增加,静止翼型的升力系数先增大后减小,其阻力系数一直增大,显示出NACA4412翼型具有较好的低风速启动性能;振荡翼型的升力系数随着攻角的变化呈现一个闭合迟滞环曲线,显示出振荡翼型S809的动态失速迟滞效应最为明显.文章参照模拟结果和对比试验数据,验证了数值模拟的可靠性.%Four kinds of aerofoil of wind turbine blade which are NACA23012, NACA4412, S809 and S810 were studied by numerical simulation method, and the aerodynamic performance of the static and oscillate aerofoil was analyzed. With the angle of attack becoming larger, the lift coefficient of the static aerofoil first increased and then decreased, however, the drag coefficient continuously increased.lt showed NACA4412 aerofoil had a better low-speed start-up performance. The lift coefficient curve of the oscillate aerofoil was presented a closed hysteresis loop cycle with the angle of attack increased. The hysteresis effect of the S809 aerofoil was most obvious. Based on the simulated data and the experiment data, the reliability of numerical simulation was verified.

  1. Introduction to wind turbine aerodynamics

    CERN Document Server

    Schaffarczyk, Alois Peter

    2014-01-01

    Wind-Turbine Aerodynamics is a self-contained textbook which shows how to come from the basics of fluid mechanics to modern wind turbine blade design. It presents a fundamentals of fluid dynamics and inflow conditions, and gives a extensive introduction into theories describing the aerodynamics of wind turbines. After introducing experiments the book applies the knowledge to explore the impact on blade design.The book is an introduction for professionals and students of very varying levels.

  2. Aerodynamics of wind turbines emerging topics

    CERN Document Server

    Amano, R S

    2014-01-01

    Focusing on Aerodynamics of Wind Turbines with topics ranging from Fundamental to Application of horizontal axis wind turbines, this book presents advanced topics including: Basic Theory for Wind turbine Blade Aerodynamics, Computational Methods, and Special Structural Reinforcement Technique for Wind Turbine Blades.

  3. Reinforced aerodynamic profile

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to the prevention of deformations in an aerodynamic profile caused by lack of resistance to the bending moment forces that are created when such a profile is loaded in operation. More specifically, the invention relates to a reinforcing element inside an aerodynamic ...... profile and a method for the construction thereof. The profile is intended for, but not limited to, useas a wind turbine blade, an aerofoil device or as a wing profile used in the aeronautical industry....

  4. aerodynamics and heat transfer

    Directory of Open Access Journals (Sweden)

    J. N. Rajadas

    1998-01-01

    Full Text Available A multidisciplinary optimization procedure, with the integration of aerodynamic and heat transfer criteria, has been developed for the design of gas turbine blades. Two different optimization formulations have been used. In the first formulation, the maximum temperature in the blade section is chosen as the objective function to be minimized. An upper bound constraint is imposed on the blade average temperature and a lower bound constraint is imposed on the blade tangential force coefficient. In the second formulation, the blade average and maximum temperatures are chosen as objective functions. In both formulations, bounds are imposed on the velocity gradients at several points along the surface of the airfoil to eliminate leading edge velocity spikes which deteriorate aerodynamic performance. Shape optimization is performed using the blade external and coolant path geometric parameters as design variables. Aerodynamic analysis is performed using a panel code. Heat transfer analysis is performed using the finite element method. A gradient based procedure in conjunction with an approximate analysis technique is used for optimization. The results obtained using both optimization techniques are compared with a reference geometry. Both techniques yield significant improvements with the multiobjective formulation resulting in slightly superior design.

  5. Helicopter rotor blade design for minimum vibration

    Science.gov (United States)

    Taylor, R. B.

    1984-01-01

    The importance of blade design parameters in rotor vibratory response and the design of a minimum vibration blade based upon this understanding are examined. Various design approaches are examined for a 4 bladed articulated rotor operating at a high speed flight condition. Blade modal shaping, frequency placement, structural and aerodynamic coupling, and intermodal cancellation are investigated to systematically identify and evaluate blade design parameters that influence blade airloads, blade modal response, hub loads, and fuselage vibration. The relative contributions of the various components of blade force excitation and response to the vibratory hub loads transmitted to the fuselage are determined in order to isolate primary candidates for vibration alleviation. A blade design is achieved which reduces the predicted fuselage vibration from the baseline blade by approximately one half. Blade designs are developed that offer significant reductions in vibration (and fatigue stresses) without resorting to special vibration alleviation devices, radical blade geometries, or weight penalties.

  6. WIND TURBINE MASS AND AERODYNAMIC IMBALANCES DETERMINATION

    OpenAIRE

    Nduwayezu Eric; Mehmet Bayrak

    2015-01-01

    This paper evaluates the use of simulations to investigate wind turbine mass and aerodynamic imbalances. Faults caused by mass and aerodynamic imbalances constitute a significant portion of all faults in wind turbine. The aerodynamic imbalances effects such as deviations between the three blades pitch angle are often underrated and misunderstood. In practice, for many wind energy converters the blade adjustment is found to be sub-optimal. The dynamics of a model wind turbine was s...

  7. Blade dynamic stress analysis of rotating bladed disks

    Directory of Open Access Journals (Sweden)

    Kellner J.

    2007-10-01

    Full Text Available The paper deals with mathematical modelling of steady forced bladed disk vibrations and with dynamic stress calculation of the blades. The blades are considered as 1D kontinuum elastic coupled with three-dimensional elastic disk centrally clamped into rotor rotating with constant angular speed. The steady forced vibrations are generated by the aerodynamic forces acting along the blade length. By using modal synthesis method the mathematical model of the rotating bladed disk is condensed to calculate steady vibrations. Dynamic stress analysis of the blades is based on calculation of the time dependent reduced stress in blade cross-sections by using Hubert-Misses-Hencky stress hypothesis. The presented method is applied to real turbomachinery rotor with blades connected on the top with shroud.

  8. Wind turbine blade vibration at standstill conditions — the effect of imposing lag on the aerodynamic response of an elastically mounted airfoil

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac

    2015-01-01

    The present study investigated physical phenomena related to stall-induced vibrations potentially existing on wind turbine blades at standstill conditions. The study considered two-dimensional airfoil sections while it omitted three-dimensional effects. In the study, a new engineering...

  9. Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems. Task 4: Advanced fan section aerodynamic analysis computer program user's manual

    Science.gov (United States)

    Crook, Andrew J.; Delaney, Robert A.

    1992-01-01

    The computer program user's manual for the ADPACAPES (Advanced Ducted Propfan Analysis Code-Average Passage Engine Simulation) program is included. The objective of the computer program is development of a three-dimensional Euler/Navier-Stokes flow analysis for fan section/engine geometries containing multiple blade rows and multiple spanwise flow splitters. An existing procedure developed by Dr. J. J. Adamczyk and associates at the NASA Lewis Research Center was modified to accept multiple spanwise splitter geometries and simulate engine core conditions. The numerical solution is based upon a finite volume technique with a four stage Runge-Kutta time marching procedure. Multiple blade row solutions are based upon the average-passage system of equations. The numerical solutions are performed on an H-type grid system, with meshes meeting the requirement of maintaining a common axisymmetric mesh for each blade row grid. The analysis was run on several geometry configurations ranging from one to five blade rows and from one to four radial flow splitters. The efficiency of the solution procedure was shown to be the same as the original analysis.

  10. Flutter control of incompressible flow turbomachine blade rows by splitter blades

    International Nuclear Information System (INIS)

    Splitter blades as a passive flutter control technique are investigated by developing a mathematical model to predict the stability of an aerodynamically loaded splittered-rotor operating in an incompressible flow field. The splitter blades, positioned circumferentially in the flow passage between two principal blades, introduce aerodynamic and/or combined aerodynamic-structural detuning into the rotor. The two-dimensional oscillating cascade unsteady aerodynamics, including steady loading effects, are determined by developing a complete first-order unsteady aerodynamic analysis together with an unsteady aerodynamic influence coefficient technique. The torsion mode flutter of both uniformly spaced tuned rotors and detuned rotors are predicted by incorporating the unsteady aerodynamic influence coefficients into a single-degree-of-freedom aeroelastic model. This model is then utilized to demonstrate that incorporating splitters into unstable rotor configurations results in stable splittered-rotor configurations. (orig.)

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

    OpenAIRE

    Li Yang; Ouyang Hua; Du Zhao-Hui

    2007-01-01

    This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP) neural network and genetic algorithm (GA), the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pres...

  12. Transonic blade flutter: A survey of new developments

    OpenAIRE

    Platzer, M.F.

    1982-01-01

    This paper presents a review of current work in transonic blade flutter research. Aerodynamic analyses for the prediction of attached flow flutter, choke flutter, and stall flutter are described. Also reviewed are unsteady aerodynamic measurement and flutter test programs that have recently been completed or are in progress to investigate transonic blade flutter phenomena.

  13. The Influence of Blade Angle on Aerodynamic Performance of Small Savonius Wind Turbine%叶片转角对小型Savonius风机气动性能的影响

    Institute of Scientific and Technical Information of China (English)

    位晓清; 王东兴; 蔡国忠

    2012-01-01

    Savonius rotor is a typical style of vertical-axis wind turbine (VAWT). The study on the aerodynamic performance of small Savonius wind turbine influenced by blade angle was presented in the paper. Fluid-solid coupling analysis on the Savonius rotor was carried out based on ANSYS CFX. And the standard k-ε turbulence model was used in the simulation analysis of savonius rotor. The power characteristics were calculated after getting the data about torque and velocity distribution by numerical simulation. And then the relation between torque coefficient and blade angle was obtained by using the analysis results. According to analysis results, got the point and the range that generating the maximum torque and the negative torque. And it can offer a useful reference for the further study on Savonius wind turbine in the future by the analysis of blade angle's influence on the turbine characters.%Savonius风机是一种典型的垂直轴风力发电机,通过对其进行流固耦合分析,研究叶片转角对风机气动性能的影响。利用ANSYS的CFX流体模块,流体湍流模型选择基于RANS的标准k-ε湍流模型,对风轮进行流固耦合分析,从而获得叶片产生的力矩情况,并计算了风机的功率特性。利用求解结果,得到了力矩系数与叶片转角之间的关系。分析了风机叶片在旋转一周中所产生的最大扭矩以及负扭矩所处的位置和范围。通过分析转角对风机性能的影响,可为今后的Savonius风机叶片形状优化和效率提升提供参考。

  14. Aerodynamic Aspects of Wind Energy Conversion

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær

    2011-01-01

    -blade geometry. The basics of the blade-element momentum theory are presented along with guidelines for the construction of airfoil data. Various theories for aerodynamically optimum rotors are discussed, and recent results on classical models are presented. State-of-the-art advanced numerical simulation tools...

  15. 多翼离心风机性能的数值计算和实验测量%Numerical Simulation and Experi-mental Measurement of Aerodynamic Performance for a Multi-Blade Centrifugal Fan

    Institute of Scientific and Technical Information of China (English)

    刘小民; 赵嘉; 李典

    2015-01-01

    采用基于Smagorinsky 模型的大涡模拟(LES)方法及FW-H方程,对不同流量工况下多翼离心风机的压力、效率、噪声等性能参数进行了数值模拟,并通过实验测量,对数值方法和计算模型的有效性及结果的准确性进行了验证。研究结果表明:在多翼离心风机内,流动涡核区域主要集中在叶轮叶片靠近蜗壳出口区域;在叶片前缘由于气流的冲击存在着较大压力区,在叶片尾缘吸力面由于流动涡脱落存在着负压分离区;随着流量增大,风机的总压和静压逐渐降低,动压逐渐增大,效率也出现先升高再下降的波动。在大流量工况下,计算获得的风机噪声为68.3dB,实验测量噪声值为69.4dB。%The large eddy simulation (LES) coupled with the Smagorinsky model and the Ffowcs Williams and Hawkings (FW-H) equation were used to numerically predict the pressure, efficiency and aerodynamic noise of a multi-blade centrifugal fan under different mass flow conditions respectively. Based on experimental measurement,the effectiv-eness of numerical simulation method and calculation model and the accuracy of results are verified.The numerical results show that the vortex core region of the multi-blade centrifugal fan appears mainly in the impeller close to the outlet of the volute. There is a region with higher pressure at the leading edge of the blade while there is a negative pressure region at the trailing edge of the blade. With the flow rate increasing, both the total pressure and the static pressure decrease at the outlet of the multi-blade centrifugal fan, the dynamic pressure increased and the efficiency increase first and then decrease. Even in the maximum flow rate condition, the noise obtained by the numerical calculation is good agreement with the experimental measurement. They are 68.3dB and 69.4dB respectively.

  16. Quiet Clean Short-haul Experimental Engine (QCSEE). The aerodynamic and mechanical design of the QCSEE over-the-wing fan

    Science.gov (United States)

    1976-01-01

    The aerodynamic and mechanical design of a fixed-pitch 1.36 pressure ratio fan for the over-the-wing (OTW) engine is presented. The fan has 28 blades. Aerodynamically, the fan blades were designed for a composite blade, but titanium blades were used in the experimental fan as a cost savings measure.

  17. Low-Noise Rotorcraft Blades

    Science.gov (United States)

    Brooks, Thomas F.

    1994-01-01

    Blades of helicopter rotors, tilt rotors, and like reshaped to reduce noise, according to proposal. Planform features combination of rearward and forward sweep. Forward sweep over large outer portion of blade constitutes primary noise-reduction feature. Relieves some of compressive effect in tip region, with consequent reduction of noise from compressive sources. Performance at high advance ratio improved. Cabin vibration and loading noise reduced by load-averaging effect of double-sweep planform. Aft-swept section provides balancing of aerodynamic and other dynamic forces on blade along 1/4-chord line of straight inboard section and along projection of line to outermost blade radius. Possible for hub-hinge forces and moments to remain within practical bounds. Provides stabilizing blade forces and moments to counteract any instability caused by forward sweep.

  18. Shape Optimization of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Wang, Xudong; Shen, Wen Zhong; Zhu, Wei Jun; Sørensen, Jens Nørkær; Chen, Jin

    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, 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...

  19. Simulation of Flexible Mechanisms in a Rotating Blade for Smart-Blade Applications

    OpenAIRE

    Paternoster, A.R.A.; Loendersloot, R.; Boer; Akkerman, R.

    2012-01-01

    The active Gurney flap technology is investigated to improve the performance of rotorblades by allowing helicopter blades to further control the lift unbalance that rises at high speed and by damping vibration loads on the rotor hub. This technology needs validation by wind tunnel testing of a scaled model blade under rotational loading. An optimised geometry of a flexible actuation system has been designed to provide motion for the deployment of the Gurney flap for a Mach-scale model blade [...

  20. 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...

  1. Smart actuation mechanisms for helicopter blades: design case for a mach-scaled model blade

    NARCIS (Netherlands)

    Paternoster, A.R.A.

    2013-01-01

    This work is part of the European project “Clean Sky”, which aims at improving the efficiency and the global transport quality of aircraft. The research, in this project, is currently focussing on active flap systems for helicopters to adapt the blade aerodynamic properties to local aerodynamic cond

  2. A CFD-informed quasi-steady model of flapping wing aerodynamics

    Science.gov (United States)

    Nakata, Toshiyuki; Liu, Hao; Bomphrey, Richard J.

    2016-01-01

    Aerodynamic performance and agility during flapping flight are determined by the combination of wing shape and kinematics. The degree of morphological and kinematic optimisation is unknown and depends upon a large parameter space. Aimed at providing an accurate and computationally inexpensive modelling tool for flapping-wing aerodynamics, we propose a novel CFD (computational fluid dynamics)-informed quasi-steady model (CIQSM), which assumes that the aerodynamic forces on a flapping wing can be decomposed into the quasi-steady forces and parameterised based on CFD results. Using least-squares fitting, we determine a set of proportional coefficients for the quasi-steady model relating wing kinematics to instantaneous aerodynamic force and torque; we calculate power with the product of quasi-steady torques and angular velocity. With the quasi-steady model fully and independently parameterised on the basis of high-fidelity CFD modelling, it is capable of predicting flapping-wing aerodynamic forces and power more accurately than the conventional blade element model (BEM) does. The improvement can be attributed to, for instance, taking into account the effects of the induced downwash and the wing tip vortex on the force generation and power consumption. Our model is validated by comparing the aerodynamics of a CFD model and the present quasi-steady model using the example case of a hovering hawkmoth. It demonstrates that the CIQSM outperforms the conventional BEM while remaining computationally cheap, and hence can be an effective tool for revealing the mechanisms of optimization and control of kinematics and morphology in flapping-wing flight for both bio-flyers and unmanned air systems.

  3. Aerodynamics of Wind Turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural...... response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element...... Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. The new material includes a description of the effects of the dynamics and how this can be modeled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Further, the...

  4. Impeller blade design method for centrifugal compressors

    Science.gov (United States)

    Jansen, W.; Kirschner, A. M.

    1974-01-01

    The design of a centrifugal impeller with blades that are aerodynamically efficient, easy to manufacture, and mechanically sound is discussed. The blade design method described here satisfies the first two criteria and with a judicious choice of certain variables will also satisfy stress considerations. The blade shape is generated by specifying surface velocity distributions and consists of straight-line elements that connect points at hub and shroud. The method may be used to design radially elemented and backward-swept blades. The background, a brief account of the theory, and a sample design are described.

  5. Advances in wind turbine blade design and materials

    DEFF Research Database (Denmark)

    well as the requirements and challenges for composite materials used in both current and future designs of wind turbine blades. Part one outlines the challenges and developments in wind turbine blade design, including aerodynamic and aeroelastic design features, fatigue loads on wind turbine blades...... fatigue resistance 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...... materials scientists and engineers, wind turbine blade manufacturers and maintenance technicians, scientists, researchers and academics....

  6. Dynamic response of active twist rotor blades

    Science.gov (United States)

    Cesnik, Carlos E. S.; Shin, Sang Joon; Wilbur, Matthew L.

    2001-02-01

    Dynamic characteristics of active twist rotor (ATR) blades are investigated analytically and experimentally in this paper. The ATR system is intended for vibration and potentially for noise reductions in helicopters through individual blade control. An aeroelastic model is developed to identify frequency response characteristics of the ATR blade with integral, generally anisotropic, strain actuators embedded in its composite construction. An ATR prototype blade was designed and manufactured to experimentally study the vibration reduction capabilities of such systems. Several bench and hover tests were conducted and those results are presented and discussed here. Selected results on sensitivity of the ATR system to collective setting (i.e. blade loading), blade rpm (i.e. centrifugal force and blade station velocity), and media density (i.e. altitude) are presented. They indicated that the twist actuation authority of the ATR blade is independent of the collective setting up to approximately 10P, and dependent on rotational speed and altitude near the torsional resonance frequency due to its dependency on the aerodynamic damping. The proposed model captures very well the physics and sensitivities to selected test parameters of the ATR system. The numerical result of the blade torsional loads show an average error of 20% in magnitude and virtually no difference in phase for the blade frequency response. Overall, the active blade model is in very good agreement with the experiments and can be used to analyze and design future active helicopter blade systems.

  7. Prediction of aerodynamic performance for MEXICO rotor

    DEFF Research Database (Denmark)

    Hong, Zedong; Yang, Hua; Xu, Haoran;

    2013-01-01

    The aerodynamic performance of the MEXICO (Model EXperiments In Controlled cOnditions) rotor at five tunnel wind speeds is predicted by making use of BEM and CFD methods, respectively, using commercial MATLAB and CFD software. Due to the pressure differences on both sides of the blade, the tip...... the reliability of the MEXICO data. Second, the SST turbulence model can better capture the flow separation on the blade and has high aerodynamic performance prediction accuracy for a horizontal axis wind turbine in axial inflow conditions. Finally, the comparisons of the axial and tangential forces as well...

  8. Unsteady aerodynamics of high work turbines

    OpenAIRE

    Richardson, David

    2009-01-01

    One method aircraft engine manufactures use to minimize engine cost and weight is to reduce the number of parts. A significant reduction includes reducing the turbine blade count or combining two moderately loaded turbines into one high-work turbine. The risk of High Cycle Fatigue in these configurations is increased by the additional aerodynamic forcing generated by the high blade loading and the nozzle trailing edge shocks. A lot of research has been done into the efficiency implications of...

  9. Design of low noise wind turbine blades using Betz and Joukowski concepts

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Hrgovan, Iva; Okulov, Valery;

    2014-01-01

    This paper presents the aerodynamic design of low noise wind turbine blades using Betz and Joukowski concepts. The aerodynamic model is based on Blade Element Momentum theory whereas the aeroacoustic prediction model is based on the BPM model. The investigation is started with a 3MW baseline...

  10. New airfoil sections for straight bladed turbine

    International Nuclear Information System (INIS)

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

  11. State of the art in wind turbine aerodynamics and aeroelasticity

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver; Sørensen, Jens Nørkær; Voutsinas, S; Sørensen, Niels N.; Aagaard Madsen, Helge

    2006-01-01

    A comprehensive review of wind turbine aeroelasticity is given. The aerodynamic part starts with the simple aerodynamic Blade Element Momentum Method and ends with giving a review of the work done applying CFD on wind turbine rotors. In between is explained some methods of intermediate complexity...

  12. Survey of Unsteady Computational Aerodynamics for Horizontal Axis Wind Turbines

    Science.gov (United States)

    Frunzulicǎ, F.; Dumitrescu, H.; Cardoş, V.

    2010-09-01

    We present a short review of aerodynamic computational models for horizontal axis wind turbines (HAWT). Models presented have a various level of complexity to calculate aerodynamic loads on rotor of HAWT, starting with the simplest blade element momentum (BEM) and ending with the complex model of Navier-Stokes equations. Also, we present some computational aspects of these models.

  13. Optimised conveying

    Energy Technology Data Exchange (ETDEWEB)

    Keller, M. [ContiTech Conveyor Belt Group (Germany)

    2004-01-01

    The paper illustrates how conveyor belts with optimised energy consumption can cut costs. It describes the project undertaken by ContiTech Conveyor Belt Group to increase the rated capacity of the conveying system at PT Kaltim Prima Coal's Eastern Kalimantan mine from 2400 tph to 3300 tph. The steel-cored conveyor belt, 27 km long, was supplied in 27 individual units and spliced onsite. The number of splices was minimised by using oval reels which reduced installation time. 2 figs.

  14. A novel folding blade of wind turbine rotor for effective power control

    International Nuclear Information System (INIS)

    Highlights: • A novel folding blade for wind turbine power control is proposed. • Wind tunnel experiments were conducted to analyze folding blade validity. • Folding blade is valid to control wind turbine power output. • Compared to pitch control, thrust was reduced by fold control in power regulation. • Optimum fold angles were found for wind turbine start up and aerodynamic brake. - Abstract: A concept of novel folding blade of horizontal axis wind turbine is proposed in current study. The folding blade comprises a stall regulated root blade section and a folding tip blade section with the fold axis inclined relative to blade span. By folding blade, lift force generated on the tip blade section changes and the moment arm also shortens, which leads to variations of power output. The blade folding actuation mechanism with servo motor and worm-gear reducer was designed. Wind turbine rotor control scheme and servo system with double feedback loops for blade fold angle control were proposed. In this study, a small folding blade model was tested in a wind tunnel to analyze its performance. The blade model performance was estimated in terms of rotation torque coefficient and thrust coefficient. Wind tunnel experiments were also conducted for pitch control using the same blade model in order to make a direct comparison. The power control, start up and aerodynamic brake performance of the folding blade were analyzed. According to the wind tunnel experiment results, fold angle magnitude significantly affected blade aerodynamic performance and the thrust characteristic together with the rotation torque characteristic of folding blade were revealed. The experiment results demonstrated that the folding blade was valid to control power output and had advantages in reducing thrust with maximum reduction of 51.1% compared to pitch control. Optimum fold angles of 55° and 90° were also found for start up and aerodynamic brake, respectively

  15. Wavy-Planform Helicopter Blades Make Less Noise

    Science.gov (United States)

    Brooks, Thomas F.

    2004-01-01

    Wavy-planform rotor blades for helicopters have been investigated for the first time in an effort to reduce noise. Two of the main sources of helicopter noise are blade/vortex interaction (BVI) and volume displacement. (The noise contributed by volume displacement is termed thickness noise.) The reduction in noise generated by a wavyplanform blade, relative to that generated by an otherwise equivalent straight-planform blade, affects both main sources: (1) the BVI noise is reduced through smoothing and defocusing of the aerodynamic loading on the blade and (2) the thickness noise is reduced by reducing gradients of thickness with respect to listeners on the ground.

  16. New Design of Blade Untwisting Device of Cyclone Unit

    Directory of Open Access Journals (Sweden)

    D. I. Misiulia

    2010-01-01

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

  17. Experimental Investigation of the Wind Turbine Blade Root Flow

    NARCIS (Netherlands)

    Akay, B.; Ferreira, C.S.; Van Bussel, G.J.W.

    2010-01-01

    Several methods from experimental to analytical are used to investigate the aerodynamics of a horizontal axis wind turbine. To understand 3D and rotational effects at the root region of a wind turbine blade, correct modeling of the flow field is essential. Aerodynamic models need to be validated by

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

    Directory of Open Access Journals (Sweden)

    Li Yang

    2007-01-01

    Full Text Available This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP neural network and genetic algorithm (GA, the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pressure ratio, stable operating range, and aerodynamic noise. Detailed flow measurement was performed in outlet flow field for investigating the responsible flow mechanisms. The optimized blade can cause a spanwise redistribution of flow toward the blade midspan and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at midspan. In addition, the measured spectrums show that the broadband noise of the impeller is dominant.

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

    OpenAIRE

    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 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 a...

  20. Flow Characteristics Study of Wind Turbine Blade with Vortex Generators

    OpenAIRE

    Hao Hu; Xin-kai Li; Bo Gu

    2016-01-01

    The blade root flow control is of particular importance to the aerodynamic characteristic of large wind turbines. The paper studies the feasibility of improving blade pneumatic power by applying vortex generators (VGs) to large variable propeller shaft horizontal axis wind turbines, with 2 MW variable propeller shaft horizontal axis wind turbine blades as research object. In the paper, three cases of VGs installation are designed; they are scattered in different chordwise position at the blad...

  1. Small Radial Compressors: Aerodynamic Design and Analysis

    OpenAIRE

    K. A. R. Ismail; Rosolen, C. V. A. G.; Benevenuto, F. J.; Lucato, D.

    1998-01-01

    This paper presents a computational procedure for the analysis of steady one-dimensional centrifugal compressor. The numerical model is based on the conservation principles of mass, momentum and energy, and has been utilized to predict the operational and aerodynamic characteristics of a small centrifugal compressor as well as determining the performance and geometry of compressor blades, both straight and curved.

  2. Small Radial Compressors: Aerodynamic Design and Analysis

    Directory of Open Access Journals (Sweden)

    K. A. R. Ismail

    1998-01-01

    Full Text Available This paper presents a computational procedure for the analysis of steady one-dimensional centrifugal compressor. The numerical model is based on the conservation principles of mass, momentum and energy, and has been utilized to predict the operational and aerodynamic characteristics of a small centrifugal compressor as well as determining the performance and geometry of compressor blades, both straight and curved.

  3. Leading edge erosion of coated wind turbine blades: Review of coating life models

    NARCIS (Netherlands)

    Slot, H.M.; Gelinck, E.R.M.; Rentrop, C.; Heider, E. van der

    2015-01-01

    Erosion of the leading edge of wind turbine blades by droplet impingement wear, reduces blade aerodynamic efficiency and power output. Eventually, it compromises the integrity of blade surfaces. Elastomeric coatings are currently used for erosion resistance, yet the life of such coatings cannot be p

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

    DEFF Research Database (Denmark)

    Castaignet, Damien; Poulsen, Niels Kjølstad; Buhl, Thomas; Wedel-Heinen, Jens Jakob

    blade root. The design model is based on a modal model of the blade structure and a steady state aerodynamic model of the blade airfoils. Depending on the output filter, loads within different frequency range are decreased. A fine tuning of the Kalman filter and of the cost function allows to decrease...

  5. Preliminary blade design using integrated computer codes

    Science.gov (United States)

    Ryan, Arve

    1988-12-01

    Loads on the root of a horizontal axis wind turbine (HAWT) rotor blade were analyzed. A design solution for the root area is presented. The loads on the blades are given by different load cases that are specified. To get a clear picture of the influence of different parameters, the whole blade is designed from scratch. This is only a preliminary design study and the blade should not be looked upon as a construction reference. The use of computer programs for the design and optimization is extensive. After the external geometry is set and the aerodynamic loads calculated, parameters like design stresses and laminate thicknesses are run through the available programs, and a blade design optimized on basis of facts and estimates used is shown.

  6. Composite Fan Blade Design for Advanced Engine Concepts

    Science.gov (United States)

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

    2004-01-01

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

  7. Aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...... Wind Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum...... method is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate the...

  8. Analytical Aerodynamic Simulation Tools for Vertical Axis Wind Turbines

    International Nuclear Information System (INIS)

    Wind power is a renewable energy source that is today the fastest growing solution to reduce CO2 emissions in the electric energy mix. Upwind horizontal axis wind turbine with three blades has been the preferred technical choice for more than two decades. This horizontal axis concept is today widely leading the market. The current PhD thesis will cover an alternative type of wind turbine with straight blades and rotating along the vertical axis. A brief overview of the main differences between the horizontal and vertical axis concept has been made. However the main focus of this thesis is the aerodynamics of the wind turbine blades. Making aerodynamically efficient turbines starts with efficient blades. Making efficient blades requires a good understanding of the physical phenomena and effective simulations tools to model them. The specific aerodynamics for straight bladed vertical axis turbine flow are reviewed together with the standard aerodynamic simulations tools that have been used in the past by blade and rotor designer. A reasonably fast (regarding computer power) and accurate (regarding comparison with experimental results) simulation method was still lacking in the field prior to the current work. This thesis aims at designing such a method. Analytical methods can be used to model complex flow if the geometry is simple. Therefore, a conformal mapping method is derived to transform any set of section into a set of standard circles. Then analytical procedures are generalized to simulate moving multibody sections in the complex vertical flows and forces experienced by the blades. Finally the fast semi analytical aerodynamic algorithm boosted by fast multipole methods to handle high number of vortices is coupled with a simple structural model of the rotor to investigate potential aeroelastic instabilities. Together with these advanced simulation tools, a standard double multiple streamtube model has been developed and used to design several straight bladed

  9. Piezoelectric Vibration Damping Study for Rotating Composite Fan Blades

    Science.gov (United States)

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

    2012-01-01

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

  10. Blade-tip heat transfer in a transonic turbine

    Energy Technology Data Exchange (ETDEWEB)

    Thorpe, S.; Yoshino, S.; Thomas, G.; Ainsworth, R. [Oxford Univ. (United Kingdom). Dept. of Engineering Science; Harvey, N. [Rolls-Royce plc., Derby (United Kingdom)

    2005-09-15

    The blade-tips of high-pressure turbine blades in a gas turbine engine are subjected to strong convective heat transfer and continued to present a significant design challenge to manufacturers. This paper is concerned with developing an understanding of the unsteady flow physics that influences the blade-tip heat transfer. Experimental investigations of bladetip heat transfer and aerodynamics have been conducted in a transonic turbine stage test facility. The data reveal the effect of vane-rotor interactions on the unsteady heat transfer along the blade-tip mean camber line. In particular, the vane shock and potential field interaction establish characteristic unsteady heat transfer signatures at different axial positions along the blade-tip. The fluctuations in heat transfer are discussed in terms of vane-periodic changes in both relative total temperature and aerodynamic conditions. (author)

  11. Massachusetts Large Blade Test Facility Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Rahul Yarala; Rob Priore

    2011-09-02

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

  12. 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. PMID:25583871

  13. Control of helicopter rotorblade aerodynamics

    Science.gov (United States)

    Fabunmi, James A.

    1991-01-01

    The results of a feasibility study of a method for controlling the aerodynamics of helicopter rotorblades using stacks of piezoelectric ceramic plates are presented. A resonant mechanism is proposed for the amplification of the displacements produced by the stack. This motion is then converted into linear displacement for the actuation of the servoflap of the blades. A design which emulates the actuation of the servoflap on the Kaman SH-2F is used to demonstrate the fact that such a system can be designed to produce the necessary forces and velocities needed to control the aerodynamics of the rotorblades of such a helicopter. Estimates of the electrical power requirements are also presented. A Small Business Innovation Research (SBIR) Phase 2 Program is suggested, whereby a bench-top prototype of the device can be built and tested. A collaborative effort between AEDAR Corporation and Kaman Aerospace Corporation is anticipated for future effort on this project.

  14. Wind wheel with a single bladed or two blade rotor arranged on a tower

    Energy Technology Data Exchange (ETDEWEB)

    Laussermair, F.; Kaiba, K.

    1980-02-14

    The invention concerns a wind wheel (impeller) with a single bladed or two blade rotor arranged on a tower. The wind speed, with which the air flows over wind wheels, is normally different over the rotor circle area. This leads to the creation of cyclic torques, which will try to turn the rotor head cyclically around the tower axis and cause torsional oscillations. It is therefore the purpose of the invention to create a wind wheel, in which the tendency of the rotor head to turn around the tower axis is reduced, without incurring losses of output. The problem of the invention is solved, by having one or more auxiliary blades in addition to the main blade or blades, which lie in the rotor plane and are cyclically adjustable around their longitudinal axis, so that their aerodynamic up thrust produces a torque around the tower axis, which practically compensates for the torque resulting from the different flow over the main blade or blades. One example of the invention achieves the adjustment of the auxiliary blades around their longitudinal axis by means of one or more levers, each of which is connected at its end to one auxiliary blade, and has a roller on its other end, which can roll around a fixed curved disc, where the roller is pressed by a spring against the curved disc.

  15. Helicopter Rotor Blade With Free Tip

    Science.gov (United States)

    Stroub, Robert H.; Young, Larry; Cawthorne, Matthew; Keys, Charles

    1992-01-01

    Free-tip rotor blades improve fuel efficiency and performance characteristics of helicopters. Outermost portion of blade pivots independently with respect to inboard portion about pitch axis parallel to blade axis, located forward of aerodynamic center. Centrifugal force acts on tension/torsion strap and biases tip nose-up. Airstream turns tip nose-down, other torques cause tip to "weathervane" to intermediate angular position resulting in net lift. Reduces fluctuations in lift, with two effects: flapwise vibratory loads on blade and vibratory loads on pitch-control mechanism reduced; negative lift produced by advancing fixed tip eliminated, reducing power required to achieve same overall lift. Applies to tilt rotors and tail rotors as well.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-09-01

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

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

    DEFF Research Database (Denmark)

    Petersen, H.

    1980-01-01

    root face and 1 m from the root face and have been verified experimentally. Aerodynamic calculations have also been performed of the power coefficient as a function of tip speed ratio for various tip chord angles for blades used in a 3-bladed and a 2-bladed rotor configuration with a diameter of 26 m....

  18. Structural integrity design for an active helicopter rotor blade with piezoelectric flap actuators

    Science.gov (United States)

    Lee, Jaehwan; Shin, SangJoon

    2011-04-01

    Helicopter uses a rotor system to generate lift, thrust and forces, and its aerodynamic environment is generally complex. Unsteady aerodynamic environment arises such as blade vortex interaction. This unsteady aerodynamic environment induces vibratory aerodynamic loads and high aeroacoustic noise. The aerodynamic load and aeroacoustic noise is at N times the rotor blade revolutions (N/rev). But conventional rotor control system composed of pitch links and swash plate is not capable of adjusting such vibratory loads because its control is restricted to 1/rev. Many active control methodologies have been examined to alleviate the problem. The blade using active control device manipulates the blade pitch angle with N/rev. In this paper, Active Trailing-edge Flap blade, which is one of the active control methods, is designed to reduce the unsteady aerodynamic loads. Active Trailing-edge Flap blade uses a trailing edge flap manipulated by an actuator to change camber line of the airfoil. Piezoelectric actuators are installed inside the blade to manipulate the trailing edge flap.

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

    Energy Technology Data Exchange (ETDEWEB)

    2004-05-01

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

  20. PREFACE: Aerodynamic sound Aerodynamic sound

    Science.gov (United States)

    Akishita, Sadao

    2010-02-01

    The modern theory of aerodynamic sound originates from Lighthill's two papers in 1952 and 1954, as is well known. I have heard that Lighthill was motivated in writing the papers by the jet-noise emitted by the newly commercialized jet-engined airplanes at that time. The technology of aerodynamic sound is destined for environmental problems. Therefore the theory should always be applied to newly emerged public nuisances. This issue of Fluid Dynamics Research (FDR) reflects problems of environmental sound in present Japanese technology. The Japanese community studying aerodynamic sound has held an annual symposium since 29 years ago when the late Professor S Kotake and Professor S Kaji of Teikyo University organized the symposium. Most of the Japanese authors in this issue are members of the annual symposium. I should note the contribution of the two professors cited above in establishing the Japanese community of aerodynamic sound research. It is my pleasure to present the publication in this issue of ten papers discussed at the annual symposium. I would like to express many thanks to the Editorial Board of FDR for giving us the chance to contribute these papers. We have a review paper by T Suzuki on the study of jet noise, which continues to be important nowadays, and is expected to reform the theoretical model of generating mechanisms. Professor M S Howe and R S McGowan contribute an analytical paper, a valuable study in today's fluid dynamics research. They apply hydrodynamics to solve the compressible flow generated in the vocal cords of the human body. Experimental study continues to be the main methodology in aerodynamic sound, and it is expected to explore new horizons. H Fujita's study on the Aeolian tone provides a new viewpoint on major, longstanding sound problems. The paper by M Nishimura and T Goto on textile fabrics describes new technology for the effective reduction of bluff-body noise. The paper by T Sueki et al also reports new technology for the

  1. INTERNAL FLOW MECHANISM AND EXPERIMENTAL RESEARCH OF LOW PRESSURE AXIAL FAN WITH FORWARD-SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    LI Yang; LIU Jie; OUYANG Hua; DU Zhao-Hui

    2008-01-01

    This article presents the flow mechanism analysis and experimental study of a forward-skewed impeller and a radial impeller in low pressure axial fan. The forward-skewed blade was obtained by the optimization design of the radial blade and CFD technique. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the forward-skewed blade has demonstrated the improvements in efficiency, total pressure ratio, Stable Operating Range (SOR) and less aerodynamic noise. Detailed flow measurement and computation were performed for outlet flow field for investigating the responsible flow mechanisms. The results show the forward-skewed blade can cause a spanwise redistribution of flow toward the blade mid-span and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at mid-span.

  2. Natural aerodynamics

    CERN Document Server

    Scorer, R S

    1958-01-01

    Natural Aerodynamics focuses on the mathematics of any problem in air motion.This book discusses the general form of the law of fluid motion, relationship between pressure and wind, production of vortex filaments, and conduction of vorticity by viscosity. The flow at moderate Reynolds numbers, turbulence in a stably stratified fluid, natural exploitation of atmospheric thermals, and plumes in turbulent crosswinds are also elaborated. This text likewise considers the waves produced by thermals, transformation of thin layer clouds, method of small perturbations, and dangers of extra-polation.Thi

  3. 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.

  4. 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.

  5. Flow Characteristics Study of Wind Turbine Blade with Vortex Generators

    Directory of Open Access Journals (Sweden)

    Hao Hu

    2016-01-01

    Full Text Available The blade root flow control is of particular importance to the aerodynamic characteristic of large wind turbines. The paper studies the feasibility of improving blade pneumatic power by applying vortex generators (VGs to large variable propeller shaft horizontal axis wind turbines, with 2 MW variable propeller shaft horizontal axis wind turbine blades as research object. In the paper, three cases of VGs installation are designed; they are scattered in different chordwise position at the blade root, and then they are calculated, respectively, with CFD method. The results show that VGs installed in the separation line upstream, with the separation line of the blade root as a benchmark, show a better effect. Pneumatic power of blades increases by 0.6% by installing VGs. Although the effect on large wind turbines is not obvious, there is a space for optimization.

  6. Computational Aerodynamics and Aeroacoustics for Wind Turbines

    DEFF Research Database (Denmark)

    Shen, Wen Zhong

    obtain more detailed information of the flow structures and to determine more accurately loads and power yield of wind turbines or cluster of wind turbines, it is required to resort to more sophisticated techniques, such as Computational Fluid Dynamics (CFD). As computer resources keep on improving year...... Computational Aero-Acoustics (CAA). With the spread of wind turbines near urban areas, there is an increasing need for accurate predictions of aerodynamically generated noise. Indeed, noise has become one of the most important issues for further development of wind power, and the ability of controlling and......To analyse the aerodynamic performance of wind turbine rotors, the main tool in use today is the 1D-Blade Element Momentum (BEM) technique combined with 2D airfoil data. Because of its simplicity, the BEM technique is employed by industry when designing new wind turbine blades. However, in order to...

  7. Optimisation of the energy potential of low-CO2 gas turbines by using large monocrystal turbine blades. Final report; Optimierung des Energiepotentials fuer CO{sub 2}-arme Gasturbinen durch grosse Einkristall-Turbinenschaufeln. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Grossmann, J.

    2002-07-01

    Apart from the experimental identification and assessment of process characteristics during industrial-scale application of the so-called liquid metal cooling (LPC) process, the project focused on the characterisation of monocrystalline, directionally solidified materials and components. This involved the construction and commissioning of appropriate production and test aggregates, i.e. the LMC casting system and a Laue orientation testing unit, as well as the modification of a vacuum heat treatment furnace to meet the specific requirement of glow annealing of monocrystalline, directionally solidified turbine blades. [German] Das Ziel des Forschungsvorhabens (Laufzeit: 01. Juli 1997 bis 31. Dezember 2001) 'Optimierung des Energiepotentials fuer CO{sub 2}-arme Gasturbinen durch grosse Einkristall-Turbinenschaufeln' lag neben der experimentellen Bestimmung und Bewertung von Verfahrens- und Prozesskennwerten bei der industriellen Umsetzung des sogenannten Liquid-Metal-Cooling-Verfahrens (LMC) in der Eigenschaftscharakterisierung von einkristallin-gerichtet erstarrten Proben und Bauteilen, die mittels dieser neuartigen Giesstechnologie dargestellt wurden. Grundvoraussetzung fuer die umfassende Bearbeitung der o.g. Arbeitsinhalte war die Konstruktion und Inbetriebnahme der notwendigen Fertigungs- und Pruefaggregate, d.h. der LMC-Giessanlage und einer Laue-Orientierungspruefeinrichtung bzw. der Abstimmung eines Vakuum-Waermebehandlungsofens auf die spezifischen Anforderungen der Loesungsgluehung einkristallin-gerichtet erstarrter Turbinenlaufschaufeln. (orig.)

  8. Hybrid Vortex Method for the Aerodynamic Analysis of Wind Turbine

    Directory of Open Access Journals (Sweden)

    Hao Hu

    2015-01-01

    Full Text Available The hybrid vortex method, in which vortex panel method is combined with the viscous-vortex particle method (HPVP, was established to model the wind turbine aerodynamic and relevant numerical procedure program was developed to solve flow equations. The panel method was used to calculate the blade surface vortex sheets and the vortex particle method was employed to simulate the blade wake vortices. As a result of numerical calculations on the flow over a wind turbine, the HPVP method shows significant advantages in accuracy and less computation resource consuming. The validation of the aerodynamic parameters against Phase VI wind turbine experimental data is performed, which shows reasonable agreement.

  9. Plasma Aerodynamic Control Effectors for Improved Wind Turbine Performance

    Energy Technology Data Exchange (ETDEWEB)

    Mehul P. Patel; Srikanth Vasudevan; Robert C. Nelson; Thomas C. Corke

    2008-08-01

    Orbital Research Inc is developing an innovative Plasma Aerodynamic Control Effectors (PACE) technology for improved performance of wind turbines. The PACE system is aimed towards the design of "smart" rotor blades to enhance energy capture and reduce aerodynamic loading and noise using flow-control. The PACE system will provide ability to change aerodynamic loads and pitch distribution across the wind turbine blade without any moving surfaces. Additional benefits of the PACE system include reduced blade structure weight and complexity that should translate into a substantially reduced initial cost. During the Phase I program, the ORI-UND Team demonstrated (proof-of-concept) performance improvements on select rotor blade designs using PACE concepts. Control of both 2-D and 3-D flows were demonstrated. An analytical study was conducted to estimate control requirements for the PACE system to maintain control during wind gusts. Finally, independent laboratory experiments were conducted to identify promising dielectric materials for the plasma actuator, and to examine environmental effects (water and dust) on the plasma actuator operation. The proposed PACE system will be capable of capturing additional energy, and reducing aerodynamic loading and noise on wind turbines. Supplementary benefits from the PACE system include reduced blade structure weight and complexity that translates into reduced initial capital costs.

  10. Aerodynamic Analysis Models for Vertical-Axis Wind Turbines

    OpenAIRE

    Brahimi, M. T.; A. Allet; I. Paraschivoiu

    1995-01-01

    This work details the progress made in the development of aerodynamic models for studying Vertical-Axis Wind Turbines (VAWT's) with particular emphasis on the prediction of aerodynamic loads and rotor performance as well as dynamic stall simulations. The paper describes current effort and some important findings using streamtube models, 3-D viscous model, stochastic wind model and numerical simulation of the flow around the turbine blades. Comparison of the analytical results with available e...

  11. Wind Tunnel Test and Numerical Computation on Ice Accretion on Blade Airfoil for Straight-bladed VAWT

    Institute of Scientific and Technical Information of China (English)

    LI Shengmao; LI Yan; FENG Fang; WANG Lijun; CHI Yuan

    2010-01-01

    To invest the condition of ice accretion on the blade used for straight-bladed vertical axis wind turbine(SB-VAWT),wind tunnel tests were carded out on a blade with NACA0015 airfoil by using a small simple icing wind tunnel.Tests were carried out at some typical attack angles under different wind speeds and flow discharges of a water spray with wind.The icing shape and area on blade surface were recorded and measured.Then the numerical computation was carried out to calculate the lift and drag coefficients of the blade before and after ice accretion according to the experiment result,the effect of icing on the aerodynamic characteristics of blade were discussed.

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

    OpenAIRE

    Chi-Jeng Bai; Wei-Cheng Wang; Po-Wei Chen; Wen-Tong Chong

    2014-01-01

    In designing a horizontal-axis wind turbine (HAWT) blade, system integration between the blade design and the performance test of the generator is important. This study shows the aerodynamic design of a HAWT blade operating with an axial-flux permanent magnet (AFPM) generator. An experimental platform was built to measure the performance curves of the AFPM generator for the purpose of designing the turbine blade. An in-house simulation code was developed based on the blade element momentum (B...

  13. An investigation of the dynamics of the horizontal wind turbine blades

    OpenAIRE

    Urieta Nieto, Itziar

    2015-01-01

    The aim of this project is to design, investigate and model the aerodynamic behavior and dynamics of a wind turbine blades taking into account the elasticity of the rotor blades and the steadiness of the flow. The main idea of the project is by performing the steady-state FSI (Fluid-Structure Interaction) analysis based on the obtained numerical results from two solvers: aerodynamic model for fluid and structural solver to evaluate the influence of the profile of wind turbin...

  14. Flowfield Analysis of Savonius-type Wind Turbine blade

    International Nuclear Information System (INIS)

    In this paper, we researched flow of 8000 ∼ 24000 Reynolds number around a blade model of Savonius-type wind turbine with experimental and numerical method. For the blade shape of arc, we analyzed flowfield with streak-image flow visualization, measured wake, computed drag coefficients, and compared them for given angle of attacks. The result of research can be used to design aerodynamic performance of Savonius-type turbine rotor directly

  15. Flowfield Analysis of Savonius-type Wind Turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Tae Hyun; Chang, Se Myong [Kunsan National Univ., Kunsan (Korea, Republic of); Seo, Hyun Soo [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2007-07-01

    In this paper, we researched flow of 8000 {approx} 24000 Reynolds number around a blade model of Savonius-type wind turbine with experimental and numerical method. For the blade shape of arc, we analyzed flowfield with streak-image flow visualization, measured wake, computed drag coefficients, and compared them for given angle of attacks. The result of research can be used to design aerodynamic performance of Savonius-type turbine rotor directly.

  16. An experimental examination of the influence of trailing-edge coolant ejection on blade losses in transonic turbine cascades

    OpenAIRE

    Bertsch, Remi

    1990-01-01

    This thesis summarizes the results of an experimental study on transonic turbine blades in the presence of ejection of coolant in the direction of the flow from slots near the trailing edge. I t presents the effect of the trailing edge coolant ejection on the turbine blade aerodynamic efficiency.l The objective of this work is to contribute to the design of new turbine blades by giving loss data for cooled blades. Data were taken in the Virginia Polytechnic Institute & State University ...

  17. Numerical simulation of turbulent flows past the RoBin helicopter with a four-bladed rotor

    International Nuclear Information System (INIS)

    The current paper presents a turbulent flow simulation study past a generic helicopter RoBin with a four-bladed rotor using the Chimera moving grid approach. The aerodynamic performance of the rotor blades and their interactions with the RoBin fuselage are investigated using the k - ω SST turbulence model contained in the WIND code. The rotor is configured as a Chimera moving grid in a quasisteady flow field. The rotor blades are rectangular, untapered, linearly twisted and are made from NACA 0012 airfoil profile. The blade motion (rotation and cyclic pitching) schedule is specified in the NASA wind tunnel testing of a generic helicopter RoBin. The aerodynamic radial load distributions in the rotor plane are generated by integrating the pressure on each blade surfaces along the blade chordwise direction. The rotor flow interacts strongly with the flow coming off from the fuselage and thus has a significant impact on helicopter aerodynamic performance. (author)

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  19. Optimisation-based clearance

    OpenAIRE

    Varga, Andras

    2002-01-01

    The basic feature of the optimisation-based clearance approach is to reformulate the clearance problems as equivalent minimum distance problems for which ”anti”-optimisation is performed to determine the worst-case parameter combination/ flight condition leading to worst performance. The basic requirements for the applicability of the optimisation-based approach are the availability of suitable parametric models describing the overall nonlinear dynamics of the augmented aircraft and of accomp...

  20. Heteroscedastic Treed Bayesian Optimisation

    OpenAIRE

    Assael, John-Alexander M.; Wang, Ziyu; Shahriari, Bobak; De Freitas, Nando

    2014-01-01

    Optimising black-box functions is important in many disciplines, such as tuning machine learning models, robotics, finance and mining exploration. Bayesian optimisation is a state-of-the-art technique for the global optimisation of black-box functions which are expensive to evaluate. At the core of this approach is a Gaussian process prior that captures our belief about the distribution over functions. However, in many cases a single Gaussian process is not flexible enough to capture non-stat...

  1. Design of broad-blade axial fans. Zur Auslegung von Breitschaufel-Axialventilatoren

    Energy Technology Data Exchange (ETDEWEB)

    Stangl, M.; Weinhold, K. (VEB Kombinat ILKA Luft- und Kaeltetechnik, Dresden (German Democratic Republic))

    1989-01-01

    An easy-to-handle calculation method is described for the aerodynamic design of broad-blade axial fans as they are often used in connection with heat exchangers. This method is tailored to impeller blades which are advantageously engineered as circular profile blades with a constant profile depth over the blade height and a constant profile angle. The results of a test design confirm both the usefulness of the calculation method and the suitability of the type of blading in various case designs. Referring to measuring results, the acoustic quality of the test fan is also confirmed. (orig.).

  2. KNOW-BLADE task-3.2 report: Tip shape study

    DEFF Research Database (Denmark)

    Sørensen, Niels N.; Johansen, Jeppe; Conway, S.; Voutsinas, S.; Hansen, M.O.L.; Stuermer, A.

    2005-01-01

    For modern rotor blades with their very large aspect ratio, the blade tip is a very limited part of the overall rotor, and as such of limited importance for the overall aerodynamics of the rotor. Even though they may not be very important for the overallpower production, the tip noise can be very...

  3. Nonlinear aeroelastic modelling for wind turbine blades based on blade element momentum theory and geometrically exact beam theory

    International Nuclear Information System (INIS)

    Due to the increasing size and flexibility of large wind turbine blades, accurate and reliable aeroelastic modelling is playing an important role for the design of large wind turbines. Most existing aeroelastic models are linear models based on assumption of small blade deflections. This assumption is not valid anymore for very flexible blade design because such blades often experience large deflections. In this paper, a novel nonlinear aeroelastic model for large wind turbine blades has been developed by combining BEM (blade element momentum) theory and mixed-form formulation of GEBT (geometrically exact beam theory). The nonlinear aeroelastic model takes account of large blade deflections and thus greatly improves the accuracy of aeroelastic analysis of wind turbine blades. The nonlinear aeroelastic model is implemented in COMSOL Multiphysics and validated with a series of benchmark calculation tests. The results show that good agreement is achieved when compared with experimental data, and its capability of handling large deflections is demonstrated. Finally the nonlinear aeroelastic model is applied to aeroelastic modelling of the parked WindPACT 1.5 MW baseline wind turbine, and reduced flapwise deflection from the nonlinear aeroelastic model is observed compared to the linear aeroelastic code FAST (Fatigue, Aerodynamics, Structures, and Turbulence). - Highlights: • A novel nonlinear aeroelastic model for wind turbine blades is developed. • The model takes account of large blade deflections and geometric nonlinearities. • The model is reliable and efficient for aeroelastic modelling of wind turbine blades. • The accuracy of the model is verified by a series of benchmark calculation tests. • The model provides more realistic aeroelastic modelling than FAST (Fatigue, Aerodynamics, Structures, and Turbulence)

  4. Turbine blade cooling: the blade temperature distribution

    Energy Technology Data Exchange (ETDEWEB)

    Horlock, J. [Cambridge University (United Kingdom). Whittle Laboratory; Torbidoni, L. [Ansaldo Energia, Genoa (Italy)

    2006-07-01

    Air cooling of high-temperature gas turbines is a standard practice; the air first cools the blading by internal convection and then by external film cooling, after ejection through holes and slots in the blade surface. In some 'conventional' analyses of turbine blade cooling, a 'standard blade' is invoked, which has a uniform blade temperature equal to the average temperature of the real blade, and estimates are made of the cooling flow required to hold the standard blade temperature to a limit set by material considerations. However, early analytical work by Ainley (for convective cooling of thin-walled blades) showed that both the coolant and blade temperatures should increase along the blade span. The current paper develops Ainley's original analysis to allow for finite blade wall thickness and thermal barrier coatings, film cooling, and variation in the mainstream gas temperature along the span. This new analysis should enable more accurate estimates to be made of cooling air flow requirements. (author)

  5. Aerodynamic noise analysis of the NW35 wind turbine number 10 in Slootdorp, Netherlands (NL)

    International Nuclear Information System (INIS)

    Experimental research has been done to reduce the aerodynamic noise production of the NW35 wind turbines of NedWind. The research focussed on the influence of the trailing edge of the rotor blades. Three different trailing edge shapes have been compared to each other,The test turbine was turbine 10 of the wind farm in Slootdorp, the Netherlands. This turbine has a two bladed rotor and a nominal power of 500 kW. Three measurement campaigns have been performed: (1) with two original blades, (2) with one original blade and one blade with a wedge shaped trailing edge, and (3) with one original blade and one blade with a sharp trailing edge. During the campaigns the flow was visualized using tufts on one blade and a rotating video camera. The acoustic noise of the two blades of the rotor has been measured simultaneously but separately using an acoustic parabola. The result of the first measurement campaign was that one of the two original blades produced much more noise than the other one. After inspection it was found that the blade tip did not close properly. The results of the other two measurement campaigns were that the noise production of blades with a wedge shaped or with a sharp trailing edge showed no significant differences with the original blade. As a consequence the manufacturer of the blades has no reason to apply specially shaped (and thus vulnerable) trailing edges. 18 figs., 2 refs

  6. Investigation of the Hydrodynamics of Sweep Blade in Hi-Speed Axial Fuel Pump Impeller

    OpenAIRE

    Ran Tao; Ruofu Xiao; Wei Yang; Fujun Wang; Yulin Wu

    2013-01-01

    Fuel pump is a crucial component in aircraft engine ignition system. For the hi-speed axial fuel pumps, rotating stall triggers vortex and affects the operation stability and security. Sweep blade is widely used to solve the stability problems in aerodynamics field. Investigation on the hydrodynamics was conducted in this study. Based on the typical straight blade pump, positive and negative sweep blade pumps were modeled. With the large eddy simulation method, CFD simulations were conducted ...

  7. Numerical investigation of blade flutter at or near stall in axial turbomachines

    OpenAIRE

    Höhn, Wolfgang

    2000-01-01

    During the design of the compressor and turbine stages oftoday's aeroengines aerodynamically induced vibrations becomeincreasingly important since higher blade load and betterefficiency are desired. Aerodynamically induced vibrations inturbomachines can be classified into two general categories,i.e. selfexcited vibrations, usually denoted as flutter, andforced response. In the first case the aerodynamic forcesacting on the structure are dependent on the motion of thestructure. In the latter c...

  8. Development of a High-fidelity Experimental Substructure Test Rig for Grid-scored Sandwich Panels in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Laustsen, Steffen; Lund, Erik; Kühlmeier, L.;

    2014-01-01

    This paper outlines high-fidelity experimental substructure testing of sandwich panels which constitute the aerodynamic outer shell of modern wind turbine blades. A full-scale structural experimental and numerical characterisation of a composite wind turbine blade has been conducted. The developm......This paper outlines high-fidelity experimental substructure testing of sandwich panels which constitute the aerodynamic outer shell of modern wind turbine blades. A full-scale structural experimental and numerical characterisation of a composite wind turbine blade has been conducted. The...

  9. Computer Based Optimisation Rutines

    DEFF Research Database (Denmark)

    Dragsted, Birgitte; Olsen, Flemmming Ove

    1996-01-01

    In this paper the need for optimisation methods for the laser cutting process has been identified as three different situations. Demands on the optimisation methods for these situations are presented, and one method for each situation is suggested. The adaptation and implementation of the methods...

  10. Actuator Control of Edgewise Vibrations in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Staino, A.; Basu, B.; Nielsen, Søren R.K.

    2012-01-01

    prescribed control law. A mathematical model of the wind turbine equipped with active controllers has been formulated using an Euler–Lagrangian approach. The model describes the dynamics of edgewise vibrations considering the aerodynamic properties of the blade, variable mass and stiffness per unit length...

  11. Wind turbine aerodynamic response under atmospheric icing conditions

    DEFF Research Database (Denmark)

    Etemaddar, M.; Hansen, Martin Otto Laver; Moan, T.

    2014-01-01

    This article deals with the atmospheric ice accumulation on wind turbine blades and its effect on the aerodynamic performance and structural response. The role of eight atmospheric and system parameters on the ice accretion profiles was estimated using the 2D ice accumulation software lewice Twenty...... Wind Power using a NACA64618 airfoil. The effects of changes in geometry and surface roughness are considered in the simulation. A blade element momentum code WT-Perf is then used to quantify the degradation in performance curves. The dynamic responses of the wind turbine under normal and iced......-four hours of icing, with time varying wind speed and atmospheric icing conditions, was simulated on a rotor. Computational fluid dynamics code, FLUENT, was used to estimate the aerodynamic coefficients of the blade after icing. The results were also validated against wind tunnel measurements performed at LM...

  12. 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.

  13. Materials, Manufacturing, and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance

    Science.gov (United States)

    Miller, Sandi G.; Handschuh, Katherine; Sinnott, Matthew J.; Kohlman, Lee W.; Roberts, Gary D.; Martin, Richard E.; Ruggeri, Charles R.; Pereira, J. Michael

    2015-01-01

    Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

  14. Aeroelastic behavior of twist-coupled HAWT blades

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

    As the technology for horizontal axis wind turbines (HAWT) development matures, more novel techniques are required for the capture of additional amounts of energy, alleviation of loads and control of the rotor. One such technique employs the use of an adaptive blade that could sense the wind velocity or rotational speed in some fashion and accordingly modify its aerodynamic configuration to meet a desired objective. This could be achieved in either an active or passive manner, although the passive approach is much more attractive due to its simplicity and economy. As an example, a blade design might employ coupling between bending and/or extension, and twisting so that, as it bends and extends due to the action of the aerodynamic and inertial loads, it also twists modifying the aerodynamic performance in some way. These performance modifications also have associated aeroelastic effects, including effects on aeroelastic instability. To address the scope and magnitude of these effects a tool has been developed for investigating classical flutter and divergence of HAWT blades. As a starting point, an adaptive version of the uniform Combined Experiment Blade will be investigated. Flutter and divergence airspeeds will be reported as a function of the strength of the coupling and also be compared to those of generic blade counterparts.

  15. Advanced Topics in Aerodynamics

    DEFF Research Database (Denmark)

    Filippone, Antonino

    1999-01-01

    "Advanced Topics in Aerodynamics" is a comprehensive electronic guide to aerodynamics,computational fluid dynamics, aeronautics, aerospace propulsion systems, design and relatedtechnology. We report data, tables, graphics, sketches,examples, results, photos, technical andscientific literature, for...

  16. BLADED IMPELLER FOR TURBOBLOWERS

    Science.gov (United States)

    Baumann, K.

    1949-10-01

    A means is given of holding open-sided impeller blades in a turbo-rotor. Two half blades, with dovetail roots of sufficient weight to contain the center of gravity, are fitted into slots cut in the rotor so as to form the desired angle between the blade faces. The adjoining edges of the half blades are welded to form one solid blade that is securely locked an the rotor. This design permits the manufacture of a V shaped impeller blade without the need of machining the entire V shaped contour from a single blank, and furthermore provides excellent locking characteristics for attachment to the rotor.

  17. Study on aerodynamic performance of axial flow fan with bowed blade based on Bezier function%Bezier函数型弯叶片的轴流风扇气动性能研究

    Institute of Scientific and Technical Information of China (English)

    周水清; 王军; 王兴双

    2013-01-01

    In order to study the impact of axial flow blade leading edge section under convexity-preserving, an optimization design of axial flow fan in meridional plane was carried out. Large eddy simulation solution method was used in 3D unsteady flows field based on Lighthill's acoustic analogy for and the prototype impeller the improved impeller. The results of internal flow analysis show that the vor-ticity distribution of the improved impeller is less than the prototype impeller under the same flow-rate and the improved impeller has the better flow field performance. At last, the experimental measuring results indicate that the improved impeller has better properties and efficiency through the flow rate-speed graph and the sound level-speed graph. Numerical simulation results agree with the measured data quite well. The noise of the improved impeller is reduced by 1. 1 dB.%为了研究轴流叶片前缘段保凸性对风扇性能的影响,采用Bezier曲线对某空调开式轴流风扇叶片子午面进行参数设计,结合大涡模拟中声类比积分求解方法,对轴流风扇原型叶轮及改进新型叶轮进行三维非定常流场计算.两种叶轮结构的内流分析表明:在相同流量下,新型叶轮涡度分布小于原型叶轮,流场性能较好.最后通过实验测试,得到了不同转速下的流量及总声级曲线图,发现改进后叶轮具有较好的外部特性,并能有效降噪1.1 dB.

  18. Further dual purpose evolutionary optimization of small wind turbine blades

    International Nuclear Information System (INIS)

    Much work has been done to maximise the power extraction of wind turbine blades. However, small wind turbines are also required to be self starting and whilst blades designed for maximum power extraction can be optimised analytically, these blades often have poor starting performance. The numeric method of Differential Evolution is used here to maximise for both power and starting performance. Standard blade element theory is used to calculate the power coefficient, and a modified blade element method for starting time. The chord and twist of each blade element make up the genes for evolution. Starting times can be improved by a factor of 20 with only a small reduction in power coefficient. With the introduction of the tip speed ratio as an additional gene, up to 10% improvement in power coefficient was achieved. A second study was done in another case where analytical optimisation is not possible; the inclusion of tip losses. The inclusion resulted in only a small increase in the optimum chord in the tip region which becomes less noticeable at lower tip speed ratios

  19. Aeroelastic stability predictions for a MW-sized blade

    Energy Technology Data Exchange (ETDEWEB)

    Lobitz, Don W. [Sandia National Labs., Albuquerque, NM (United States)

    2004-07-01

    Classical aeroelastic flutter instability historically has not been a driving issue in wind turbine design. In fact, rarely has this issue even been addressed in the past. Commensurately, among the wind turbines that have been built, rarely has classical flutter ever been observed. However, with the advent of larger turbines fitted with relatively softer blades, classical flutter may become a more important design consideration. In addition, innovative blade designs involving the use of aeroelastic tailoring, wherein the blade twists as it bends under the action of aerodynamic loads to shed load resulting from wind turbulence, may increase the blade's proclivity for flutter. With these considerations in mind it is prudent to revisit aeroelastic stability issues for a MW-sized blade with and without aeroelastic tailoring. Focusing on aeroelastic stability associated with the shed wake from an individual blade turning in still air, the frequency domain technique developed by Theodorsen for predicting classical flutter in fixed wing aircraft has been adapted for use with a rotor blade. Results indicate that the predicted flutter speed of a MW-sized blade is slightly greater than twice the operational speed of the rotor. When a moderate amount of aeroelastic tailoring is added to the blade, a modest decrease (12%) in the flutter speed is predicted. By comparison, for a smaller rotor with relatively stiff blades the predicted flutter speed is approximately six times the operating speed. When frequently used approximations to Theodorsen's method are implemented, drastic underpredictions result, which, while conservative, may adversely impact blade design. These underpredictions are also evident when this MW-sized blade is analysed using time domain methods. (Author)

  20. Bistable devices for morphing rotor blades

    Science.gov (United States)

    Johnson, Terrence

    This dissertation presents two bistable concepts for morphing rotor blades. These concepts are simple and are composed of bistable devices that act as coupling structures between an actuator and the rotor blade. Bistable or "snap-through" mechanisms have two stable equilibrium states and are a novel way to achieve large actuation output stroke at relatively modest effort for gross rotor morphing applications. This is because in addition to the large actuation stroke associated with the snap-through (relative to conventional actuator/ amplification systems) coming at relatively low actuation effort, no locking is required in either equilibrium state (since they are both stable). The first concept that is presented in this dissertation is a that is composed of a bistable twisting device that twists the tip of helicopter rotor blades. This work examines the performance of the presented bistable twisting device for rotor morphing, specifically, blade tip twist under an aerodynamic lift load. The device is analyzed using finite element analysis to predict its load carrying capability and bistable behavior. The second concept that is presented is a concept that is composed of a bistable arch for rotor blade chord extension. The bistable arch is coupled to a thin flat plate that is supported by rollers. Increasing the chord of the rotor blade is expected to generate more lift-load and improve helicopter performance. In this work, a methodology is presented to design the bistable arches for chord morphing using the finite element analysis and pseudo-rigid body model method. This work also examines the effect of different arches, arch hinge size and shape, inertial loads and rigidity on arch performance. Finally, this work shows results from an experiment that was conducted to validate the developed numerical model and demonstrates how the arch can be actuated using a Nitinol Shape Memory Alloy (SMA) wire to extend the chord of a helicopter rotor blade.

  1. Vortex-induced vibration effect on fatigue life estimate of turbine blades

    Science.gov (United States)

    Lau, Y. L.; Leung, R. C. K.; So, R. M. C.

    2007-11-01

    An analysis of a turbine blade fatigue life that includes the physics of fluid-structure interaction on the high cycle fatigue (HCF) life estimate of turbine blades is carried out. The rotor wake excitation is modeled by rows of Karman vortices superimposed on an inviscid uniform flow. The vortex-induced vibration problem is modeled by a linear cascade composed of five turbine blades and the coupled Euler and structural dynamics equations are numerically solved using a time-marching boundary element technique. The analysis can be applied to any blade geometries; it is not limited to the blade geometry considered here. Two major design parameters have been identified; the ratio of blade spacing to blade chord length s/ c of the stator, and the normalized frequency parameter c/ d which is related to the wake passing frequency of the rotor. For a rigid cascade, it is found that aerodynamic resonance prevails at the resonant c/ d values corresponding to an isolated blade while s/ c is responsible for the level of the aerodynamic response. If the central blades were elastic, the parameter s/ c plays a different role in the fluid-structure interaction problem. With a c/ d that could lead to structural resonance for an isolated blade, changing s/ c would stabilize the aerodynamic and structural response of the elastic blade in a cascade. On the contrary, an improper choice of s/ c might turn the elastic blade response into structural resonance even though the oncoming c/ d is non-resonant. The results of the nonlinear effects of c/ d and s/ c could be used together with the Campbell diagram to obtain an improved HCF design of rotor-stator pair.

  2. Turbomachine blade reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Crespo, Andres Jose

    2016-09-06

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

  3. 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...

  4. Wireless Inductive Power Device Suppresses Blade Vibrations

    Science.gov (United States)

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

    2011-01-01

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

  5. A Hybrid Metaheuristic-Based Approach for the Aerodynamic Optimization of Small Hybrid Wind Turbine Rotors

    Directory of Open Access Journals (Sweden)

    José F. Herbert-Acero

    2014-01-01

    Full Text Available This work presents a novel framework for the aerodynamic design and optimization of blades for small horizontal axis wind turbines (WT. The framework is based on a state-of-the-art blade element momentum model, which is complemented with the XFOIL 6.96 software in order to provide an estimate of the sectional blade aerodynamics. The framework considers an innovative nested-hybrid solution procedure based on two metaheuristics, the virtual gene genetic algorithm and the simulated annealing algorithm, to provide a near-optimal solution to the problem. The objective of the study is to maximize the aerodynamic efficiency of small WT (SWT rotors for a wide range of operational conditions. The design variables are (1 the airfoil shape at the different blade span positions and the radial variation of the geometrical variables of (2 chord length, (3 twist angle, and (4 thickness along the blade span. A wind tunnel validation study of optimized rotors based on the NACA 4-digit airfoil series is presented. Based on the experimental data, improvements in terms of the aerodynamic efficiency, the cut-in wind speed, and the amount of material used during the manufacturing process were achieved. Recommendations for the aerodynamic design of SWT rotors are provided based on field experience.

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

    Directory of Open Access Journals (Sweden)

    Ranjeet Agarwala

    2015-01-01

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

  7. ANALYTICAL METHODS FOR CALCULATING FAN AERODYNAMICS

    Directory of Open Access Journals (Sweden)

    Jan Dostal

    2015-12-01

    Full Text Available This paper presents results obtained between 2010 and 2014 in the field of fan aerodynamics at the Department of Composite Technology at the VZLÚ aerospace research and experimental institute in Prague – Letnany. The need for rapid and accurate methods for the preliminary design of blade machinery led to the creation of a mathematical model based on the basic laws of turbomachine aerodynamics. The mathematical model, the derivation of which is briefly described below, has been encoded in a computer programme, which enables the theoretical characteristics of a fan of the designed geometry to be determined rapidly. The validity of the mathematical model is assessed continuously by measuring model fans in the measuring unit, which was developed and manufactured specifically for this purpose. The paper also presents a comparison between measured characteristics and characteristics determined by the mathematical model as the basis for a discussion on possible causes of measured deviations and calculation deviations.

  8. Optical Measurements of Axial and Tangential Steady-State Blade Deflections Obtained Simultaneously

    Science.gov (United States)

    Kurkov, Anatole P.; Dhadwal, Harbans S.

    2000-01-01

    Case-mounted fiber-optic sensors have been used by aircraft engine manufacturers mainly to monitor blade vibration in fans and compressors. The simplest probe arrangement is a spot probe where, typically, a center fiber transmits laser light, and the outer fibers collect the reflected light from the blade tips and transmit it to a photodetector. Because the spot of incident light is fixed in space, whereas the blade deflects dynamically, the reflected light will originate from slightly different portions of the blade tip under different operating conditions. Unless corrections are developed to compensate for this effect, some error in vibratory tangential amplitude will occur. For monitoring vibrations, this error is usually not critical. However, when steady-state blade deflections are being measured, it is very important to fix the spot on the blade tip at a particular location because the operating speed blade deflections are evaluated against a low-speed reference run. The change in speed usually implies a significant change in the blade orientation and possibly its shape brought about by the aerodynamic and centrifugal loading. It is most convenient to select the blade s leading and trailing edges as the fixed points for which deflections will be evaluated. To capture the blade edges at various speeds, the light probe must be movable. This was achieved by mounting the probe in an eccentric hole in a bushing that fit the fan case in the region that overlapped the path of the blade edge. The probe was actuated to search for a blade edge while all the blades were viewed on an oscilloscope. The blade edge was considered to be captured when a pulse associated with a particular blade was significantly reduced in magnitude but was clearly distinguishable from the background noise level. By tracing the axial position of either blade edge, one could extend the deflection measurement to two dimensions: axial and tangential. These blade deflection measurements were

  9. Basic rotor aerodynamics applied to wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, M.O.L.

    1998-01-01

    It is the hope of the author that the notes will impart a basic understanding of the mechanisms behind the production of forces on a wind turbine. Even though aero-elastic codes, including a standard Blade Element Momentum method, can be bought, it is considered important that the theory behind this method and its limitations is understood. The aerodynamics of a wind turbine is important, but building a wind turbine is a multi disciplinary task since it requires knowledge of meteorology, atmospheric turbulence, fluid mechanics, structural dynamics, generators, electrical grid connections, gear boxes, hydraulics, foundations, economics and so on. (au) 14 refs.

  10. 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.

  11. Optimization design of blade shapes for wind turbines

    DEFF Research Database (Denmark)

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

    2010-01-01

    For the optimization design of wind turbines, the new normal and tangential induced factors of wind turbines are given considering the tip loss of the normal and tangential forces based on the blade element momentum theory and traditional aerodynamic model. The cost model of the wind turbines and...... the optimization design model are developed. In the optimization model, the objective is the minimum cost of energy and the design variables are the chord length, twist angle and the relative thickness. Finally, the optimization is carried out for a 2 MW blade by using this optimization design model....... The performance of blades is validated through the comparison and analysis of the results. The reduced cost shows that the optimization model is good enough for the design of wind turbines. The results give a proof for the design and research on the blades of large scale wind turbines and also...

  12. 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.

  13. Prediction of rotor blade-vortex interaction using Volterra integrals

    International Nuclear Information System (INIS)

    The theory of Volterra integral equations for nonlinear system is applied to the prediction of the nonlinear aerodynamic response of an NACA 0012 airfoil experiencing blade-vortex interaction. The phenomenon is first modeled in two-dimensions using an Euler/Navier-Stoke code, and the resulting unsteady aerodynamic flow field sequences are appropriately combined to form a training dataset. The Volterra kernels are identified in the time-domain characteristics of the selected data, which is in turn used to predict the nonlinear aerodynamic response of the airfoil. The Volterra kernel based data is then compared against a standard airfoil response. The predicted lift time histories of the airfoil are shown to be in good agreement with the aerodynamic data. (author)

  14. The SNL100-03 Blade: Design Studies with Flatback Airfoils for the Sandia 100-meter Blade.

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, Daniel; Richards, Phillip William

    2014-09-01

    A series of design studies were performed to inv estigate the effects of flatback airfoils on blade performance and weight for large blades using the Sandi a 100-meter blade designs as a starting point. As part of the study, the effects of varying the blade slenderness on blade structural performance was investigated. The advantages and disadvantages of blad e slenderness with respect to tip deflection, flap- wise & edge-wise fatigue resistance, panel buckling capacity, flutter speed, manufacturing labor content, blade total weight, and aerodynamic design load magn itude are quantified. Following these design studies, a final blade design (SNL100-03) was prod uced, which was based on a highly slender design using flatback airfoils. The SNL100-03 design with flatback airfoils has weight of 49 tons, which is about 16% decrease from its SNL100-02 predecessor that used conventional sharp trailing edge airfoils. Although not systematically optimized, the SNL100 -03 design study provides an assessment of and insight into the benefits of flatback airfoils for la rge blades as well as insights into the limits or negative consequences of high blade slenderness resulting from a highly slender SNL100-03 planform as was chosen in the final design definition. This docum ent also provides a description of the final SNL100-03 design definition and is intended to be a companion document to the distribution of the NuMAD blade model files for SNL100-03, which are made publicly available. A summary of the major findings of the Sandia 100-meter blade development program, from the initial SNL100-00 baseline blade through the fourth SNL100-03 blade study, is provided. This summary includes the major findings and outcomes of blade d esign studies, pathways to mitigate the identified large blade design drivers, and tool development that were produced over the course of this five-year research program. A summary of large blade tec hnology needs and research opportunities is also presented.

  15. 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.

  16. Blade by Blade Tip Clearance Measurement

    OpenAIRE

    A. G. Sheard

    2011-01-01

    This paper describes a capacitance-based tip clearance measurement system which engineers have used in the most demanding turbine test applications. The capacitance probe has survived extended use in a major European gas turbine manufacturer's high-temperature demonstrator unit, where it functioned reliably at a turbine entry temperature in excess of 1800 degrees Kelvin. This paper explores blade by blade tip clearance measurement techniques and examines probe performance under laboratory con...

  17. Resonances and Aerodynamic Damping of a Vertical Axis Wind Turbine

    OpenAIRE

    Ottermo, Fredric; Bernhoff, Hans

    2012-01-01

    The dynamics of a straight-bladed vertical axis wind turbine is investigated with respect to oscillations due to the elasticity of struts and shaft connecting to the hub. In particular, for the three-bladed turbine, a concept is proposed for dimensioning the turbine to maximize the size of the resonance free rpm range for operation. The effect of aerodynamic damping on the struts is also considered. The damping of these types of oscillations for a typical turbine is found to be good.

  18. ANALYTICAL APPROACH TO AERODYNAMIC CHARACTERISTICS OF THE HELICOPTER ROTOR WITH ANHEDRAL TIP SHAPE

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A new analytical approach, based on a lifting surface model and a full-span free wake analysis using the curved vortex element on the circular arc, is established for evaluating the aerodynamic characteristics of the helicopter rotor with an anhedral blade-tip and is emphasized to be applicable to various blade-tip configurations, such as the tapered, swept, anhedral and combined shapes. Sample calculations on the rotor aerodynamic characteristics for different anhedral tips in both hover and forward flight are performed. The results on the induced velocity, blade section lift distribution, tip vortex path and rotor performance are presented so that the effect of the anhedral tip on the rotor aerodynamic characteristics is fully analyzed.

  19. Numerical study of improving aerodynamic performance of low solidity LPT cascade through increasing trailing edge thickness

    Science.gov (United States)

    Li, Chao; Yan, Peigang; Wang, Xiangfeng; Han, Wanjin; Wang, Qingchao

    2016-08-01

    This paper presents a new idea to reduce the solidity of low-pressure turbine (LPT) blade cascades, while remain the structural integrity of LPT blade. Aerodynamic performance of a low solidity LPT cascade was improved by increasing blade trailing edge thickness (TET). The solidity of the LPT cascade blade can be reduced by about 12.5% through increasing the TET of the blade without a significant drop in energy efficiency. For the low solidity LPT cascade, increasing the TET can decrease energy loss by 23.30% and increase the flow turning angle by 1.86% for Reynolds number (Re) of 25,000 and freestream turbulence intensities (FSTI) of 2.35%. The flow control mechanism governing behavior around the trailing edge of an LPT cascade is also presented. The results show that appropriate TET is important for the optimal design of high-lift load LPT blade cascades.

  20. Optimization design of spar cap layup for wind turbine blade

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Based on the aerodynamic shape and structural form of the blade are fixed,a mathematical model of optimization design for wind turbine blade is established.The model is pursued with respect to minimum the blade mass to reduce the cost of wind turbine production.The material layup numbers of the spar cap are chosen as the design variables;while the demands of strength,stiffness and stability of the blade are employed as the constraint conditions.The optimization design for a 1.5 MW wind turbine blade is carried out by combing above objective and constraint conditions at the action of ultimate flapwise loads with the finite element software ANSYS.Compared with the original design,the optimization design result achieves a reduction of 7.2% of the blade mass,the stress and strain distribution of the blade is more reasonable,and there is no occurrence of resonance,therefore its effectiveness is verified.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    no mechanical or metal parts are used. The prototypes tested in the laboratory and on a blade section in a wind tunnel in the period from 2007-2010 demonstrated the functionality and the aerodynamic performance of the flap concept. In a recent research and development project INDUFLAP from 2011......-2014 the flap system has been further developed in corporation with the industrial partners Hydratech Industries (DK) and Rehau (DE). A new trailing edge flap design with spanwise voids (channels) and with a chord of 15cm suitable for a 1m chord blade section was developed. It was then manufactured by...

  2. Integrated airfoil and blade design method for large wind turbines

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong; Sørensen, Jens Nørkær

    2014-01-01

    of 3 million. A novel shape perturbation function is introduced to optimize the geometry based on the existing airfoils which simplifies the design procedure. The viscous/inviscid interactive code XFOIL is used as the aerodynamic tool for airfoil optimization at a Reynolds number of 16 million and a...... free-stream Mach number of 0.25 near the tip. Results show that the new airfoils achieve a high power coefficient in a wide range of angles of attack (AOA) and are extremely insensitive to surface roughness. Finally, a full blade analysis using computational fluid dynamics (CFD) and blade element...

  3. Multidisciplinary Design Optimization for Glass-Fiber Epoxy-Matrix Composite 5 MW Horizontal-Axis Wind-Turbine Blades

    Science.gov (United States)

    Grujicic, M.; Arakere, G.; Pandurangan, B.; Sellappan, V.; Vallejo, A.; Ozen, M.

    2010-11-01

    A multi-disciplinary design-optimization procedure has been introduced and used for the development of cost-effective glass-fiber reinforced epoxy-matrix composite 5 MW horizontal-axis wind-turbine (HAWT) blades. The turbine-blade cost-effectiveness has been defined using the cost of energy (CoE), i.e., a ratio of the three-blade HAWT rotor development/fabrication cost and the associated annual energy production. To assess the annual energy production as a function of the blade design and operating conditions, an aerodynamics-based computational analysis had to be employed. As far as the turbine blade cost is concerned, it is assessed for a given aerodynamic design by separately computing the blade mass and the associated blade-mass/size-dependent production cost. For each aerodynamic design analyzed, a structural finite element-based and a post-processing life-cycle assessment analyses were employed in order to determine a minimal blade mass which ensures that the functional requirements pertaining to the quasi-static strength of the blade, fatigue-controlled blade durability and blade stiffness are satisfied. To determine the turbine-blade production cost (for the currently prevailing fabrication process, the wet lay-up) available data regarding the industry manufacturing experience were combined with the attendant blade mass, surface area, and the duration of the assumed production run. The work clearly revealed the challenges associated with simultaneously satisfying the strength, durability and stiffness requirements while maintaining a high level of wind-energy capture efficiency and a lower production cost.

  4. Rotor blade dynamic design

    Science.gov (United States)

    Pritchard, Jocelyn I.; Adelman, Howard M.; Mantay, Wayne R.

    1989-01-01

    The rotor dynamic design considerations are essentially limitations on the vibratory response of the blades which in turn limit the dynamic excitation of the fuselage by forces and moments transmitted to the hub. Quantities which are associated with the blade response and which are subject to design constraints are discussed. These include blade frequencies, vertical and inplane hub shear, rolling and pitching moments, and aeroelastic stability margin.

  5. Investigation of the Aerodynamic Character in Turbine Cascades with Aft-loaded Profile

    Institute of Scientific and Technical Information of China (English)

    周逊; 韩万金

    2004-01-01

    For evaluate the aerodynamic character of the turbine cascades which have the aft-loaded profile, the experimental investigation was carried out on the low speed annular wind tunnel. And the detailed measurements of the aerodynamic parameters were made from upstream to downstream of the two type turbine cascades, the one is the conventional straight blades cascade, the other is the curved blades cascades. The static pressure distributions on the endwall and the blade surface were also carried out. The influence of the aft-loaded profile and the curved blade on the development of loss and the pressure distribution was discussed, and analyses the different flow phenomena and mechanism in two type turbine cascades.

  6. Aerodynamic Optimization of Vertical Axis Wind Turbine with Trailing Edge Flaps

    DEFF Research Database (Denmark)

    Ertem, Sercan; Ferreira, Carlos; Gaunaa, Mac;

    2016-01-01

    Vertical Axis Wind Turbines (VAWT) are competitive concepts for very large scale (1020 MW) floating offshore applications. Rotor circulation control (loading control) opens a wide design space to enhance the aerodynamic and operational features of VAWT. The modified linear derivation of the...... Actuator Cylinder Model (Mod-Lin ACM) is used as the aerodynamic model to assess VAWT performance throughout the work. As the first step, optimum aerodynamic loadings of a VAWT with infinite number of blades are studied. Next, for the case of finite number of blades, direct and inverse optimization...... approaches are used. The direct method is coupled with a hybrid numerical optimizer to serve as a global method for designing flap sequences. The effectiveness of trailing edge flap on VAWT is investigated for three aerodynamic objectives which lead to improved power efficiency, rated power control and peak...

  7. Aerodynamic Optimization of Vertical Axis Wind Turbine with Trailing Edge Flap

    DEFF Research Database (Denmark)

    Ertem, Sercan; Ferreira, Carlos Simao; Gaunaa, Mac;

    2016-01-01

    Vertical Axis Wind Turbines (VAWT) are competitive concepts for very large scale (10-20 MW)floating ofshore applications. Rotor circulation control (loading control) opens a wide design space to enhance the aerodynamic and operational features of VAWT. The modied linear derivation of the Actuator....... The direct method is coupled with a hybrid numerical optimizer to serve as a global method for designingap sequences. The efectiveness of trailing edgeap on VAWT is investigated for three aerodynamic objectives which lead to improved power effciency, rated power control and peak load control. The...... Cylinder Model (Mod-Lin ACM) is used as the aerodynamic model to assess VAWT performance throughout the work. As the rst step, optimum aerodynamic loadings of a VAWT with innite number of blades are studied. Next, for the case of nite number of blades, direct and inverse optimization approaches are used...

  8. Reduction of helicopter blade-vortex interaction noise by active rotor control technology

    Science.gov (United States)

    Yu, Yung H.; Gmelin, Bernd; Splettstoesser, Wolf; Philippe, Jean J.; Prieur, Jean; Brooks, Thomas F.

    Helicopter blade-vortex interaction noise is one of the most severe noise sources and is very important both in community annoyance and military detection. Research over the decades has substantially improved basic physical understanding of the mechanisms generating rotor blade-vortex interaction noise and also of controlling techniques, particularly using active rotor control technology. This paper reviews active rotor control techniques currently available for rotor blade-vortex interaction noise reduction, including higher harmonic pitch control, individual blade control, and on-blade control technologies. Basic physical mechanisms of each active control technique are reviewed in terms of noise reduction mechanism and controlling aerodynamic or structural parameters of a blade. Active rotor control techniques using smart structures/materials are discussed, including distributed smart actuators to induce local torsional or flapping deformations.

  9. Reduction of Helicopter Blade-Vortex Interaction Noise by Active Rotor Control Technology

    Science.gov (United States)

    Yu, Yung H.; Gmelin, Bernd; Splettstoesser, Wolf; Brooks, Thomas F.; Philippe, Jean J.; Prieur, Jean

    1997-01-01

    Helicopter blade-vortex interaction noise is one of the most severe noise sources and is very important both in community annoyance and military detection. Research over the decades has substantially improved basic physical understanding of the mechanisms generating rotor blade-vortex interaction noise and also of controlling techniques, particularly using active rotor control technology. This paper reviews active rotor control techniques currently available for rotor blade vortex interaction noise reduction, including higher harmonic pitch control, individual blade control, and on-blade control technologies. Basic physical mechanisms of each active control technique are reviewed in terms of noise reduction mechanism and controlling aerodynamic or structural parameters of a blade. Active rotor control techniques using smart structures/materials are discussed, including distributed smart actuators to induce local torsional or flapping deformations, Published by Elsevier Science Ltd.

  10. The Effect of Composite Flexures on Aeroelastic Stability of a Hingeless Rotor Blade

    Institute of Scientific and Technical Information of China (English)

    Shi; Qinghua

    2007-01-01

    The effects of ply orientation angle of composite flexures on stability of hingeless rotor blade system are studied.The composite hingeless rotor blade system is simplified as a hub,a flap flexure and a lag flexure.pitch bearing and main blade.The kinematics formulations are inferred by employing the moderate deflection beam theory.The shear deformation and warping related to torsion are considered.The quasi-steady strip theory with dynamic inflow effects is applied to obtain the aerodynamic loads acting on the blade.Based on these.the set of finite element formulations of a hingeless rotor blade system is worked out.The numerical results show that the ply angle of the composite flexures has great effects on the aeroelastic stability of rotor blade.

  11. Unsteady transonic aerodynamics

    International Nuclear Information System (INIS)

    Various papers on unsteady transonic aerodynamics are presented. The topics addressed include: physical phenomena associated with unsteady transonic flows, basic equations for unsteady transonic flow, practical problems concerning aircraft, basic numerical methods, computational methods for unsteady transonic flows, application of transonic flow analysis to helicopter rotor problems, unsteady aerodynamics for turbomachinery aeroelastic applications, alternative methods for modeling unsteady transonic flows

  12. Computation of dragonfly aerodynamics

    Science.gov (United States)

    Gustafson, Karl; Leben, Robert

    1991-04-01

    Dragonflies are seen to hover and dart, seemingly at will and in remarkably nimble fashion, with great bursts of speed and effectively discontinuous changes of direction. In their short lives, their gossamer flight provides us with glimpses of an aerodynamics of almost extraterrestrial quality. Here we present the first computer simulations of such aerodynamics.

  13. A Hybrid Metaheuristic-Based Approach for the Aerodynamic Optimization of Small Hybrid Wind Turbine Rotors

    DEFF Research Database (Denmark)

    Herbert-Acero, José F.; Martínez-Lauranchet, Jaime; Probst, Oliver;

    2014-01-01

    the aerodynamic efficiency of small WT (SWT) rotors for a wide range of operational conditions. The design variables are (1) the airfoil shape at the different blade span positions and the radial variation of the geometrical variables of (2) chord length, (3) twist angle, and (4) thickness along the...... blade span. A wind tunnel validation study of optimized rotors based on the NACA 4-digit airfoil series is presented. Based on the experimental data, improvements in terms of the aerodynamic efficiency, the cut-in wind speed, and the amount of material used during themanufacturing process were achieved...

  14. Wind energy conversion. Volume II. Aerodynamics of horizontal axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Miller, R.H.; Dugundji, J.; Martinez-Sanchez, M.; Gohard, J.; Chung, S.; Humes, T.

    1978-09-01

    The basic aerodynamic theory of the wind turbine is presented, starting with the simple momentum theory based on uniform inflow and an infinite number of blades. The basic vortex theory is then developed. Following these basics, the more complete momentum theory, including swirl, non-uniform inflow, the effect of a finite number of blades, and empirical correction for the vortex ring condition is presented. The more complete vortex theory is presented which includes unsteady aerodynamic effects but based on a semi-rigid wake. Methods of applying this theory for performance estimation are discussed as well as for the purpose of computing time varying airloads due to windshear and tower interference.

  15. OPTIMAT Blades. Reliable Optimal Use of Materials for Wind Turbine Rotor Blades. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, L.G.J. [ECN Wind Energy, Petten (Netherlands); Van Wingerde, A.M.; Nijssen, R.P.L. [Knowledge Centre Wind Trubine Materials and Constructions, Delft (Netherlands); Philippidis, T.P. [University of Patras, Patras (Greece); Broendsted, P. [Risoe National Laboratory, Roskilde (Denmark); Dutton, A.G. [Council for the Central Laboratory of Research Councils CCLRC, Chilton, Didcot (United Kingdom); Kensche, C.W. [Deutsches Zentrum fuer Luft- und Raumfahrt, Berlin (Germany)

    2006-06-15

    As the required financial investments to achieve the expansion of the installed capacity of wind turbine grow, the economical pressure on reliable and structurally optimised blades, that are fit for their designed life, will increase. Very large blades may even become practically impossible without further knowledge of the material behaviour since the dominating loads on the material are caused by the blade mass. Therefore, a sound and accurate understanding of the structural behaviour of the material under all for wind turbine applications possible loading conditions is necessary. The project aims to provide accurate design recommendations for the optimised use of materials within wind turbine rotor blades and to achieve improved reliability. The major deliverable of the project will be improved design recommendations for the next generation of rotor blades. With the accurate and reliable design recommendations resulting from this project, reliable blades with optimised use of materials can be designed. The increased reliability and weight reduction of the blades will stimulate further the offshore exploitation with large capacity wind turbines. This supports the increase in wind energy and by that helps to reach the White Paper target of 40GW of installed power by 2010. The possible reduction of the material use will lower the impact on earth's resources and environment. The reduction can result from direct weight saving and from the increased reliability which prevents the need for replacements and waste of material. To execute the research activities a consortium was formed consisting of 10 research institutes from 7 EU countries; 5 wind turbine and/or blade manufactures from 3 EU countries; and the two leading certification bodies that carry out wind turbine certification throughout the world today. Over 3000 individual tests have been carried out on epoxy GFRP coupons, with numerous technical reports being issued to analyse and understand this data. The

  16. Prediction of the aerodynamic performance of the Mexico rotor by using airfoil data extracted from CFD

    OpenAIRE

    Hua YANG; Shen, Wen Zhong; Xu, Haoran; Hong, Zedong; Liu, Chao

    2013-01-01

    Blade Element Momentum (BEM) theory is a widely used technique for prediction of wind turbine aerodynamics performance, but the reliability of airfoil data is an important factor to improve the prediction accuracy of aerodynamic loads and power using a BEM code. The airfoil characteristics used in BEM codes are mostly based on 2D wind tunnel measurements of airfoils with constant span. However, a BEM code using airfoil data obtained directly from 2D wind tunnel measurements will not yield the...

  17. Aerodynamics of Vertical Axis Wind Turbines : Development of Simulation Tools and Experiments

    OpenAIRE

    Dyachuk, Eduard

    2015-01-01

    This thesis combines measurements with the development of simulation tools for vertical axis wind turbines (VAWT). Numerical models of aerodynamic blade forces are developed and validated against experiments. The studies were made on VAWTs which were operated at open sites. Significant progress within the modeling of aerodynamics of VAWTs has been achieved by the development of new simulation tools and by conducting experimental studies.         An existing dynamic stall model was investigate...

  18. Fluid-structure interaction of a wind turbine blade employing a refined finite element model coupled with a blade-element momentum method

    OpenAIRE

    Peeters, Mathijs; Van Paepegem, Wim

    2015-01-01

    Typically the aero-elastic simulation tools that are used in industry employ simple beam models to represent the blades of a wind turbine. The aerodynamic loads are usually calculated using a fast blade-element momentum (BEM) method. These models allow relatively fast calculation of the aero-elastic behavior of the blade which is required in order to allow the simulation of a large number of load cases as required by the IEC 61400 [1] and GL [2] standards in a feasible amount of time. Such b...

  19. Notes to Aerodynamic Testing of Supersonic Blade Cascades

    Czech Academy of Sciences Publication Activity Database

    Šimurda, David; Luxa, Martin; Šafařík, Pavel

    Praha: Ústav termomechaniky AV ČR, v. v. i., 2014 - (Jonáš, P.; Uruba, V.), s. 27-28 ISBN 978-80-87012-53-6. [Colloquium FLUID DYNAMICS 2014. Praha (CZ), 22.10.2014-24.10.2014] R&D Projects: GA TA ČR(CZ) TA03020277 Institutional support: RVO:61388998 Keywords : upesonic turbine cascade * supersonic flow * experiment * test section Subject RIV: BK - Fluid Dynamics

  20. Actuator control of edgewise vibrations in wind turbine blades

    Science.gov (United States)

    Staino, A.; Basu, B.; Nielsen, S. R. K.

    2012-03-01

    Edgewise vibrations with low aerodynamic damping are of particular concern in modern multi-megawatt wind turbines, as large amplitude cyclic oscillations may significantly shorten the life-time of wind turbine components, and even lead to structural damages or failures. In this paper, a new blade design with active controllers is proposed for controlling edgewise vibrations. The control is based on a pair of actuators/active tendons mounted inside each blade, allowing a variable control force to be applied in the edgewise direction. The control forces are appropriately manipulated according to a prescribed control law. A mathematical model of the wind turbine equipped with active controllers has been formulated using an Euler-Lagrangian approach. The model describes the dynamics of edgewise vibrations considering the aerodynamic properties of the blade, variable mass and stiffness per unit length and taking into account the effect of centrifugal stiffening, gravity and the interaction between the blades and the tower. Aerodynamic loads corresponding to a combination of steady wind including the wind shear and the effect of turbulence are computed by applying the modified Blade Element Momentum (BEM) theory. Multi-Blade Coordinate (MBC) transformation is applied to an edgewise reduced order model, leading to a linear time-invariant (LTI) representation of the dynamic model. The LTI description obtained is used for the design of the active control algorithm. Linear Quadratic (LQ) regulator designed for the MBC transformed system is compared with the control synthesis performed directly on an assumed nominal representation of the time-varying system. The LQ regulator is also compared against vibration control performance using Direct Velocity Feedback (DVF). Numerical simulations have been carried out using data from a 5-MW three-bladed Horizontal-Axis Wind Turbine (HAWT) model in order to study the effectiveness of the proposed active controlled blade design in

  1. Design optimization and analysis of vertical axis wind turbine blade

    International Nuclear Information System (INIS)

    Wind energy is clean and renwable source of energy and is also the world's fastest growing energy resource. Keeping in view power shortages and growing cost of energy, the low cost wind energy has become a primary solution. It is imperative that economies and individuals begin to conserve energy and focus on the production of energy from renewable sources. Present study describes a wind turbine blade designed with enhanced aerodynamic properties. Vertical axis turbine is chosen because of its easy installment, less noisy and having environmental friendly characteristics. Vertical axis wind turbines are thought to be ideal for installations where wind conditions are not consistent. The presented turbine blade is best suitable for roadsides where the rated speed due to vehicles is most /sup -1/ often 8 ms .To get an optimal shape design symmetrical profile NACA0025 has been considered which is then analyzed for stability and aerodynamic characteristics at optimal conditions using analysis tools ANSYS and CFD tools. (author)

  2. KNOW-BLADE task-4 report: Navier-Stokes aeroelasticity

    DEFF Research Database (Denmark)

    Politis, E.S.; Nikolaou, I.G.; Chaviaropoulos, P.K.;

    2004-01-01

    wind turbine blade have been combined with 2D and 3D unsteady Navier-Stokes solvers. The relative disadvantage of the quasi-3D approach (where the elastic solver is coupled with a 2D Navier-Stokes solver) isits inability to model induced flow. The lack of a validation test case did not allow for......The problem of the aeroelastic stability of wind turbine blades is addressed in this report by advancing the aerodynamic modelling in the beam element type codes from the engineering-type empirical models to unsteady, 2D or 3D, Navier-Stokes solvers. Inthis project, structural models for the full...... in damping with the increase of wind speeds and in a minimum value for the damping for wind speedaround 15~m/s. The eigenvalue analyses resulted in steeper distributions for this mode. The agreement in aerodynamic damping decrease with the increase of wind speed is also observed in the distributions...

  3. Structural response of fiber composite fan blades

    Science.gov (United States)

    Chamis, C. C.; Minich, M. D.

    1975-01-01

    A fiber composite airfoil, typical for high-tip speed compressor applications, is subjected to load conditions anticipated to be encountered in such applications, and its structural response is theoretically investigated. The analysis method used consists of composite mechanics embedded in pre- and post-processors and coupled with NASTRAN. The load conditions examined include thermal due to aerodynamic heating, pressure due to aerodynamic forces, centrifugal, and combinations of these. The various responses investigated include root reactions due to various load conditions, average composite and ply stresses, ply delaminations, and the fundamental modes and the corresponding reactions. The results show that the thermal and pressure stresses are negligible compared to those caused by the centrifugal forces. Also, the core-shell concept for composite blades is an inefficient design (core plies not highly stressed) and appears to be sensitive to interply delaminations. The results are presented in graphical and tabular forms to illustrate the types and amount of data required for such an analysis, and to provide quantitative data of the various responses which can be helpful in designing such composite blades.

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

    OpenAIRE

    Rio Melvin Aro. T; EZHILMARAN G

    2015-01-01

    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 t...

  5. Numerical simulation of the tip aerodynamics and acoustics test

    Science.gov (United States)

    Tejero E, F.; Doerffer, P.; Szulc, O.; Cross, J. L.

    2016-04-01

    The application of an efficient flow control system on helicopter rotor blades may lead to improved aerodynamic performance. Recently, our invention of Rod Vortex Generators (RVGs) has been analyzed for helicopter rotor blades in hover with success. As a step forward, the study has been extended to forward flight conditions. For this reason, a validation of the numerical modelling for a reference helicopter rotor (without flow control) is needed. The article presents a study of the flow-field of the AH-1G helicopter rotor in low-, medium- and high-speed forward flight. The CFD code FLOWer from DLR has proven to be a suitable tool for the aerodynamic analysis of the two-bladed rotor without any artificial wake modelling. It solves the URANS equations with LEA (Linear Explicit Algebraic stress) k-ω model using the chimera overlapping grids technique. Validation of the numerical model uses comparison with the detailed flight test data gathered by Cross J. L. and Watts M. E. during the Tip Aerodynamics and Acoustics Test (TAAT) conducted at NASA in 1981. Satisfactory agreements for all speed regimes and a presence of significant flow separation in high-speed forward flight suggest a possible benefit from the future implementation of RVGs. The numerical results based on the URANS approach are presented not only for a popular, low-speed case commonly used in rotorcraft community for CFD codes validation but preferably for medium- and high-speed test conditions that have not been published to date.

  6. Optimisation of radiation protection

    International Nuclear Information System (INIS)

    Optimisation of radiation protection is one of the key elements in the current radiation protection philosophy. The present system of dose limitation was issued in 1977 by the International Commission on Radiological Protection (ICRP) and includes, in addition to the requirements of justification of practices and limitation of individual doses, the requirement that all exposures be kept as low as is reasonably achievable, taking social and economic factors into account. This last principle is usually referred to as optimisation of radiation protection, or the ALARA principle. The NEA Committee on Radiation Protection and Public Health (CRPPH) organised an ad hoc meeting, in liaison with the NEA committees on the safety of nuclear installations and radioactive waste management. Separate abstracts were prepared for individual papers presented at the meeting

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

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, J.; Soerensen, N.N.; Reck, M. (and others)

    2005-01-01

    The present report describes the work done in work package WP3.3: Aerodynamic Accessories in 3D in the EC project KNOW-BLADE. Vortex generators (VGs) are modelled in 3D Navier-Stokes solvers and applied on the flow around an airfoil and a wind turbine blade. Three test cases have been investigated. 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 been measured in the VELUX wind tunnel with and without VGs placed at different chord wise positions. Three of the partners have modelled the airfoil section as a thin airfoil section with symmetry boundary conditions in the span wise direction to simulate an array of VGs. The wind turbine blade is the LM19.1 blade equipped with one pair of VGs placed at radius = 8.5 m. In general all partners have successfully modelled 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 effort spend 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 turbulence modelling has to be carried out in future projects before parametric variations can be investigated. (au)

  8. Design Oriented Aerodynamic Modelling of Wind Turbine Performance

    International Nuclear Information System (INIS)

    The development of a wind turbine aerodynamics model using a Boundary Integral Equation model (BIEM) is presented. The methodology is valid to study inviscid unsteady flows around three dimensional bodies of arbitrary shape and arbitrarily moving with respect to the incoming flow. The extension of this methodology to study viscosity effects in turbine blade flow at high angle of attack is addressed and an approach to determine aerodynamic loads over a wide range of turbine operating conditions is proposed. Numerical applications considering a selected test cases from the NREL experimental dataset are presented. Finally, the application of the proposed turbine aerodynamics model into a multi-disciplinary study including aeroelasticity of pylon-turbine assembly and aeroacoustics modelling of induced noise is briefly described

  9. Repair welding of cracked steam turbine blades

    International Nuclear Information System (INIS)

    The procedure for repair welding of cracked steam turbine blades made of martensitic stainless steels has been developed using the gas tungsten arc welding process. Weld repair procedures were developed using both ER316L austenitic stainless steel filler wire and ER410 martensitic stainless steel filler wire. The repair welding procedure with austenitic filler wire was developed to avoid preheating of the blade as also hydrogen induced cold cracking, and involved evaluation of three different austenitic filler wires, viz. ER309L, ER316L and ERNiCr-3. The overall development of the repair welding procedure included selection of welding consumables (for austenitic filler metal), optimisation of post weld heat treatment parameters, selection of suitable method for local pre-heating and post-weld heat treatment (PWHT) of the blades, determination of mechanical properties of weldments in as-welded and PWHT conditions, and microstructural examination. After various trials using different procedures, the procedure of local PWHT using electrical resistance heating on the top surface of the weldment and monitoring the temperature by placing a thermocouple at the bottom of the weld, was found to give the most satisfactory results. A similar procedure was used for preheating while using ER410 filler metal. Mechanical testing of weldments before and after PWHT involved tensile tests at room temperature, face and root bend tests, and microhardness measurements across the fusion line and heat affected zone. During procedure qualification, mock-ups and actual repair welding, dye penetrant testing was used at different stages and where ever possible radiography was carried out. These procedures were developed for repair welding of cracked blades in the low-pressure (LP) steam turbines of Indian nuclear power plants. The procedure with ER316 L filler wire has so far been applied for repair welding of 2 cracked blades (made of AISI 410 SS) of LP steam turbines, while the procedure

  10. Repair welding of cracked steam turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Bhaduri, A.K.; Gill, T.P.S.; Albert, S.K.; Shanmugam, K.; Iyer, D.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)]|[Nuclear Power Corp., Mumbai (India)

    1999-07-01

    The procedure for repair welding of cracked steam turbine blades made of martensitic stainless steels has been developed using the gas tungsten arc welding process. Weld repair procedures were developed using both ER316L austenitic stainless steel filler wire and ER410 martensitic stainless steel filler wire. The repair welding procedure with austenitic filler wire was developed to avoid preheating of the blade as also hydrogen induced cold cracking, and involved evaluation of three different austenitic filler wires, viz. ER309L, ER316L and ERNiCr-3. The overall development of the repair welding procedure included selection of welding consumables (for austenitic filler metal), optimisation of post weld heat treatment parameters, selection of suitable method for local pre-heating and post-weld heat treatment (PWHT) of the blades, determination of mechanical properties of weldments in as-welded and PWHT conditions, and microstructural examination. After various trials using different procedures, the procedure of local PWHT using electrical resistance heating on the top surface of the weldment and monitoring the temperature by placing a thermocouple at the bottom of the weld, was found to give the most satisfactory results. A similar procedure was used for preheating while using ER410 filler metal. Mechanical testing of weldments before and after PWHT involved tensile tests at room temperature, face and root bend tests, and microhardness measurements across the fusion line and heat affected zone. During procedure qualification, mock-ups and actual repair welding, dye penetrant testing was used at different stages and where ever possible radiography was carried out. These procedures were developed for repair welding of cracked blades in the low-pressure (LP) steam turbines of Indian nuclear power plants. The procedure with ER316 L filler wire has so far been applied for repair welding of 2 cracked blades (made of AISI 410 SS) of LP steam turbines, while the procedure

  11. Optimisation in radiotherapy II: Programmed and inversion optimisation algorithms

    International Nuclear Information System (INIS)

    This is the second article in a three part examination of optimisation in radiotherapy. The previous article established the bases of optimisation in radiotherapy, and the formulation of the optimisation problem. This paper outlines several algorithms that have been used in radiotherapy, for searching for the best irradiation strategy within the full set of possible strategies. Two principle classes of algorithm are considered - those associated with mathematical programming which employ specific search techniques, linear programming type searches or artificial intelligence - and those which seek to perform a numerical inversion of the optimisation problem, finishing with deterministic iterative inversion. (author)

  12. Optimisation in radiotherapy. II: Programmed and inversion optimisation algorithms.

    Science.gov (United States)

    Ebert, M

    1997-12-01

    This is the second article in a three part examination of optimisation in radiotherapy. The previous article established the bases of optimisation in radiotherapy, and the formulation of the optimisation problem. This paper outlines several algorithms that have been used in radiotherapy, for searching for the best irradiation strategy within the full set of possible strategies. Two principle classes of algorithm are considered--those associated with mathematical programming which employ specific search techniques, linear programming-type searches or artificial intelligence--and those which seek to perform a numerical inversion of the optimisation problem, finishing with deterministic iterative inversion. PMID:9503694

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

    International Nuclear Information System (INIS)

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

  14. Ultimate strength of a large wind turbine blade

    DEFF Research Database (Denmark)

    Jensen, Find Mølholt

    2009-01-01

    behaviour of wind turbine blades. Four failure mechanisms observed during the fullscale tests and the corresponding FE-analysis are presented. Elastic mechanisms associated with failure, such as buckling, localized bending and the Brazier effect, are studied. In the thesis six different types of structural......The present PhD project contains a study of the structural static strength of wind turbine blades loaded in flap-wise direction. A combination of experimental and numerical work has been used to address the most critical failure mechanisms and to get an understanding of the complex structural...... reinforcements helping to prevent undesired structural elastic mechanisms are presented. The functionality of two of the suggested structural reinforcements was demonstrated in full-scale tests and the rest trough FE-studies. The blade design under investigation consisted of an aerodynamic airfoil and a load...

  15. Three-dimensional inverse method for aerodynamic optimization in compressor

    International Nuclear Information System (INIS)

    Design experience plays an important role in compressor design. Accumulated design experience is used to reduce the number of simulations and to make time for the whole optimization process to be compatible with industrial standards. However, the major drawbacks of this design strategy are that the design result depends on talented designers with rich design experience and this method does not easily produce better configurations than existing designs. These drawbacks are related to the parametric description of the blade, which is conventionally performed using only geometric parameters. A good solution to this problem is to use a blade parametrization based on an inverse design method. Inverse design methods have been widely used for the design of various kinds of turbomachines, proving that it is a valuable alternative to the iterative use of direct methods. One main design parameter in the inverse design approach is the blade loading on both the hub and the shroud along the meridional direction. The blade loading distributions have a more direct relationship to the aerodynamic performance because they influence the flow field in a more straight-forward way. Fewer design parameters are then required to describe the blade shape than a purely geometric expression of the blade. Therefore, an optimization design method using the inverse method to parameterize the blade geometry can reduce the overall optimization time. The optimization design process then gives the optimal blade loading distributions, instead of the optimal combination of the geometric parameters. This is a more general result which can be applied to similar design problems without repeating the optimization process

  16. Aerodynamic design of a 300 kW horizontal axis wind turbine for province of Semnan

    International Nuclear Information System (INIS)

    Highlights: ► We model a 300 kW HAWT for Haddadeh in Semnan. ► BEM method employed RISØ-A1-18 aerofoil. ► Rotor design is based on a cubic wind speed. ► Cubic wind speed is calculated from Weibull distribution. ► Weibull distribution uses 1 year wind data in Haddadeh. - Abstract: In this research, Blade Element Momentum theory (BEM) is used to design a HAWT blade for a 300 kW horizontal axis wind turbine. The airfoil is RISØ-A1-18, produced by RISØ National Laboratory, Denmark. Desirable properties of this airfoil are related to enhancement of aerodynamic and structure interactions. Design parameters considered here are wind tip speed ratio, nominal wind speed and diameter of rotor. The nominal wind speed was obtained from statistical analysis of wind speed data from province of Semnan in Iran. BEM is used for obtaining maximum lift to drag ratio for each elemental constitution of the blade. Obtaining chord and twist distribution at assumed tip speed ratio of blade, the aerodynamic shape of the blade in every part is specified which correspond to maximum accessible power coefficient. The design parameters are trust coefficients, power coefficient, angle of attack, angle of relative wind, drag and lift coefficients, axial and angular induction factors. The blade design distributions are presented versus rotor radius for BEM results. The blade shape then can be modified for ease of manufacturing, structural concerns, and to reduce costs.

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

    DEFF Research Database (Denmark)

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

    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...... 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...

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    The flow field past the rotating blade of a horizontal axis wind turbine has been modeled with a full 3-D steady-RANS approach. Flow computations have been performed using the commercial finite-volume solver Fluent. A number of blade sections from the 3-D rotating geometry were chosen and the...... output are proposed for the analyzed flow situations. The main features of the boundary layer flow are described, for both the rotating blade and the corresponding 2-D profiles. Computed pressure distributions and aerodynamic coefficients evidence less lift losses after separation in the 3-D rotating...

  19. Noise reduction for centrifugal fan with non-isometric forward-swept blade impeller

    Institute of Scientific and Technical Information of China (English)

    Jianfeng MA; Datong QI; Yijun MAO

    2008-01-01

    To reduce the noise of the T9-19No.4A centri-fugal fan, whose impeller has equidistant forward-swept blades, two new impellers with different blade spacing were designed and an experimental study was conducted. Both the fan's aerodynamic performance and noise were measured when the two redesigned impellers were com-pared with the original ones. The test results are discussed in detail and the effect of the noise reduction method for a centrifugal fan using impellers with non-isometric for-ward-swept blades was analyzed, which can serve as a reference for researches on reduction of fan noise.

  20. 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

  1. Optimisation and common sense

    International Nuclear Information System (INIS)

    This note builds on recent articles about the development of new ICRP recommendations by supporting the use of common sense in optimisation; use of an additional criterion relating to technology-based principles is suggested to support utility- and equity-based criteria. This is taken forward by use of authoritative good practice safety precautions and a need to consider safety in an integrated manner. It is noted that use of common sense in ALARP or ALARA decisions is liable to rely on access to information and training. (author)

  2. Optimisation of Microstrip Antenna

    Directory of Open Access Journals (Sweden)

    H. El Hamchary

    1996-04-01

    Full Text Available When choosing the most appropriate microstrip antenna configuration for particular applications, the kind of excitation of the radiating element is an essential factor that requires careful considerations. For controlling the distribution of energy of the linear or planar array of elements and for coupling energy to the individual elements, a wide variety of feed mechanisms are available. In this paper, the coaxial antenna feeding is assumed and the best (optimised feeding is found. Then, antenna characteristics such as radiation pattern, return loss, input impedance, and VSWR are obtained.

  3. Aeroelasticity and structural optimization of composite helicopter rotor blades with swept tips

    Science.gov (United States)

    Yuan, K. A.; Friedmann, P. P.

    1995-01-01

    This report describes the development of an aeroelastic analysis capability for composite helicopter rotor blades with straight and swept tips, and its application to the simulation of helicopter vibration reduction through structural optimization. A new aeroelastic model is developed in this study which is suitable for composite rotor blades with swept tips in hover and in forward flight. The hingeless blade is modeled by beam type finite elements. A single finite element is used to model the swept tip. Arbitrary cross-sectional shape, generally anisotropic material behavior, transverse shears and out-of-plane warping are included in the blade model. The nonlinear equations of motion, derived using Hamilton's principle, are based on a moderate deflection theory. Composite blade cross-sectbnal properties are calculated by a separate linear, two-dimensional cross section analysis. The aerodynamic loads are obtained from quasi-steady, incompressible aerodynamics, based on an implicit formulation. The trim and steady state blade aeroelastic response are solved in a fully coupled manner. In forward flight, where the blade equations of motion are periodic, the coupled trim-aeroelastic response solution is obtained from the harmonic balance method. Subsequently, the periodic system is linearized about the steady state response, and its stability is determined from Floquet theory.

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

    Science.gov (United States)

    Coroneos, Rula M.

    2012-01-01

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

  5. 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.

  6. Blade attachment assembly

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Optimisation of tree path pipe network with nonlinear optimisation method

    OpenAIRE

    Doberšek, Danijela; Goričanec, Darko

    2009-01-01

    Optimisation of tree path pipe network with nonlinear optimisation method correspondance: Corresponding author. Tel.: +00386 2 22 07 761; fax: +00386 2 22 94 476. (Dobersek, D.) (Dobersek, D.) Faculty of Chemistry and Chemical Engineering--> , University of Maribor--> , Smetanova ul. 17--> , 2000 Maribor--> - SLOVENIA (Dobersek, D.) Faculty of Chemistry and Chemical Engineerin...

  8. Shape optimisation and performance analysis of flapping wings

    KAUST Repository

    Ghommem, Mehdi

    2012-09-04

    In this paper, shape optimisation of flapping wings in forward flight is considered. This analysis is performed by combining a local gradient-based optimizer with the unsteady vortex lattice method (UVLM). Although the UVLM applies only to incompressible, inviscid flows where the separation lines are known a priori, Persson et al. [1] showed through a detailed comparison between UVLM and higher-fidelity computational fluid dynamics methods for flapping flight that the UVLM schemes produce accurate results for attached flow cases and even remain trend-relevant in the presence of flow separation. As such, they recommended the use of an aerodynamic model based on UVLM to perform preliminary design studies of flapping wing vehicles Unlike standard computational fluid dynamics schemes, this method requires meshing of the wing surface only and not of the whole flow domain [2]. From the design or optimisation perspective taken in our work, it is fairly common (and sometimes entirely necessary, as a result of the excessive computational cost of the highest fidelity tools such as Navier-Stokes solvers) to rely upon such a moderate level of modelling fidelity to traverse the design space in an economical manner. The objective of the work, described in this paper, is to identify a set of optimised shapes that maximise the propulsive efficiency, defined as the ratio of the propulsive power over the aerodynamic power, under lift, thrust, and area constraints. The shape of the wings is modelled using B-splines, a technology used in the computer-aided design (CAD) field for decades. This basis can be used to smoothly discretize wing shapes with few degrees of freedom, referred to as control points. The locations of the control points constitute the design variables. The results suggest that changing the shape yields significant improvement in the performance of the flapping wings. The optimisation pushes the design to "bird-like" shapes with substantial increase in the time

  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. 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.

  11. Individual-blade-control research in the MIT VTOL Technology Laboratory 1977-1985

    Science.gov (United States)

    Ham, N. D.

    1986-01-01

    A new, advanced system for active control of helicopters and its application to the solution of rotor aerodynamic and aeroelastic problems is described. Each blade is individually controlled in the rotating frame over a wide range of frequencies. Application of the system to gust alleviation, attitude stabilization, vibration alleviation, blade lag damping augmentation, stall flutter suppression, blade flapping stabilization, stall alleviation, and performance enhancement is outlined. The effectiveness of the system in achieving most of these applications is demonstrated by experimental results from wind tunnel tests of a model helicopter rotor with individual blade control. The feasibility of achieving many or all of the applications of individual blade control using the conventional helicopter swash plate is demonstrated, and the necessary control laws are presented.

  12. Blade Testing Trends (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Desmond, M.

    2014-08-01

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

  13. A Global Optimisation Toolbox for Massively Parallel Engineering Optimisation

    CERN Document Server

    Biscani, Francesco; Yam, Chit Hong

    2010-01-01

    A software platform for global optimisation, called PaGMO, has been developed within the Advanced Concepts Team (ACT) at the European Space Agency, and was recently released as an open-source project. PaGMO is built to tackle high-dimensional global optimisation problems, and it has been successfully used to find solutions to real-life engineering problems among which the preliminary design of interplanetary spacecraft trajectories - both chemical (including multiple flybys and deep-space maneuvers) and low-thrust (limited, at the moment, to single phase trajectories), the inverse design of nano-structured radiators and the design of non-reactive controllers for planetary rovers. Featuring an arsenal of global and local optimisation algorithms (including genetic algorithms, differential evolution, simulated annealing, particle swarm optimisation, compass search, improved harmony search, and various interfaces to libraries for local optimisation such as SNOPT, IPOPT, GSL and NLopt), PaGMO is at its core a C++ ...

  14. Nonlinear Equations of Motion for Cantilever Rotor Blades in Hover with Pitch Link Flexibility, Twist, Precone, Droop, Sweep, Torque Offset, and Blade Root Offset

    Science.gov (United States)

    Hodges, D. H.

    1976-01-01

    Nonlinear equations of motion for a cantilever rotor blade are derived for the hovering flight condition. The blade is assumed to have twist, precone, droop, sweep, torque offset and blade root offset, and the elastic axis and the axes of center of mass, tension, and aerodynamic center coincident at the quarter chord. The blade is cantilevered in bending, but has a torsional root spring to simulate pitch link flexibility. Aerodynamic forces acting on the blade are derived from strip theory based on quasi-steady two-dimensional airfoil theory. The equations are hybrid, consisting of one integro-differential equation for root torsion and three integro-partial differential equations for flatwise and chordwise bending and elastic torsion. The equations are specialized for a uniform blade and reduced to nonlinear ordinary differential equations by Galerkin's method. They are linearized for small perturbation motions about the equilibrium operating condition. Modal analysis leads to formulation of a standard eigenvalue problem where the elements of the stability matrix depend on the solution of the equilibrium equations. Two different forms of the root torsion equation are derived that yield virtually identical numerical results. This provides a reasonable check for the accuracy of the equations.

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

    International Nuclear Information System (INIS)

    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

  16. Design of a Tapered and Twisted Blade for the NREL Combined Experiment Rotor; TOPICAL

    International Nuclear Information System (INIS)

    A tapered/twisted blade was designed to operate on the Combined Experiment Rotor (CER) of the National Renewable Energy Lab., which is a stall-regulated downwind wind turbine having a rated power of 20 kilowatt. The geometry of the new blade set was optimized based on annual energy production subject to the constraints imposed on the design. These constraints were mainly related to scientific needs for fundamental research in rotor aerodynamics. A trade-off study was conducted to determine the effect of the different design constraints. Based on the results of this study, which considered nonlinear twist and taper distributions as well as the NREL S809, S814, S822 and S823 airfoils, a blade having a linear taper and a nonlinear twist distribution that uses the S809 airfoil from root to tip was selected. This blade configuration is the logical continuation of the previous constant-chord twisted and untwisted blade sets and will facilitate comparison with those earlier blades. Despite th e design constraints based on scientific needs, the new blade is more representative of commercial blades than the previous blade sets

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

    NARCIS (Netherlands)

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

    2014-01-01

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

  18. Characterization of blade throw from a 2.3MW horizontal axis wind turbine upon failure

    DEFF Research Database (Denmark)

    Sarlak, Hamid; Sørensen, Jens Nørkær

    2015-01-01

    The present work concerns aerodynamics of thrown objects from a 2.3 MW Horizontal Axis Wind Turbine (HAWT), as a consequence of blade failure. The governing set of ordinary differential equations for the flying objects are derived and numerically solved using a 4th order Runge-Kutta time advancing...

  19. Simulation of flutter and forced response in turbomachinery blade rows; Simulation von Flattern und aerodynamischer Zwangserregung in Turbomaschinenbeschaufelungen

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, S.

    2003-07-01

    An aerodynamic prediction method for turbomachinery flows is extended to an aeroelastic simulation system. The aerodynamic method is first adapted to allow the prediction of flow unsteadiness caused by vibrating blade rows. A fluid-structure coupling module, including a modal model for the structural dynamics, is then incorporated to enable the direct computation of the blade response caused by the unsteady aerodynamic forces. After model verification using simple test cases, a turbine cascade suffering from flutter, as well as a compressor stage featuring forced response from blade row interaction, are investigated. The results for both configurations agree well with unsteady experimental data. The fully coupled simulations are in very good agreement with a decoupled system analysis. The principle of superposition, as it is applied in industrial forced response analysis, is fully verified even at the level of unsteady flow details. (orig.)

  20. Correlation of airloads on a two-bladed helicopter rotor

    Science.gov (United States)

    Fernandez, Francisco J.; Johnson, Wayne

    1993-01-01

    Airloads measured on a two-bladed helicopter rotor in flight during the Ames' Tip Aerodynamic and Acoustic Test are compared with calculations from a comprehensive helicopter analysis (CAMRAD/JA), and the pressures compared with calculations from a full-potential rotor code (FPR). The flight-test results cover an advance ratio range of 0.19 to 0.38. The lowest-speed case is characterized by the presence of significant blade-vortex interactions. Good correlation of peak-to-peak vortex-induced loads and the corresponding pressures is obtained. Results of the correlation for this two-bladed rotor are substantially similar to those for three- and four-bladed rotors, including the tip-vortex core size for best correlation, calculation of the peak-to-peak loads on the retreating side, and calculation of vortex iduced loads on inboard radial stations. The higher-speed cases are characterized by the presence of transonic flow on the outboard sections of the blade. Comparison of calculated and measured airloads on the advancing side is not considered appropriate because the presence of shocks makes chordwise integration of the measured data difficult. However, good correlation of the corresponding pressures is obtained.

  1. Integration of Airfoil Design during the design of new blades

    Energy Technology Data Exchange (ETDEWEB)

    Sartori, L.; Bottasso, L.; Croce, A. [Politecnico di Milano, Milan (Italy); Grasso, F. [ECN Wind Power, Petten (Netherlands)

    2013-09-15

    Despite the fact that the design of a new blade is a multidisciplinary task, often the different disciplines are combined together at later stage. Looking at the aerodynamic design, it is common practice design/select the airfoils first and then design the blade in terms of chord and twist based on the initial selection of the airfoils. Although this approach is quite diffused, it limits the potentialities of obtaining optimal performance. The present work is focused on investigating the benefits of designing the external shape of the blade including the airfoil shapes together with chord and twist. To accomplish this, a design approach has been developed, where an advanced gradient based optimization algorithm is able to control the shape of the blade. The airfoils described in the work are the NACA 4 digits, while the chord distribution and the twist distribution are described through Bezier curves. In this way, the complexity of the problem is limited while a versatile geometrical description is kept. After the details of the optimization scheme are illustrated, several numerical examples are shown, demonstrating the advantages in terms of performance and development time of integrating the design of the airfoils during the optimization of the blade.

  2. Optimiser les ressources humaines

    OpenAIRE

    Henriet, Bruno; Krohmer, Cathy

    2013-01-01

    Dans les trois organisations que nous avons étudiées, la démarche cherche d’abord à optimiser la gestion des ressources humaines pour s’assurer de l’adaptation des compétences des salariés aux besoins stratégiques de l’entreprise. La démarche est alors un moyen d’atteindre les compétences, en termes de niveau et de contenu, requises par les modèles productifs. Ce type de démarche a été observé dans trois entreprises de la région Pays de la Loire. La première, Fenêtre, est une menuiserie indus...

  3. A low-order model for analysing effects of blade fatigue load control

    Energy Technology Data Exchange (ETDEWEB)

    Kallesoee, B.S. [Technical Univ. of Denmark, Dept. of Mechanical Engineering, Lyngby (Denmark)

    2006-07-01

    A new low-order mathematical model is introduced to analyse blade dynamics and blade load-reducing control strategies for wind turbines. The model consists of a typical wing section model combined with a rotor speed model, leading to four structural degrees of freedom (flapwise, edgewise and torsional blade oscillations and rotor speed). The aerodynamics is described by an unsteady aerodynamic model. The equations of motion are derived in non-linear and linear form. The linear equations of motion are used for stability analysis and control design. The non-linear 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 the performance of one proportional-integral-derivative controller and two full-state feedback controllers. (Author)

  4. Prediction of optimum section pitch angle distribution along wind turbine blades

    International Nuclear Information System (INIS)

    Highlights: ► Prediction of optimum pitch angle along wind turbine blades. ► Maximum electrical power extraction at the installation site. ► Solving BEM equations with the probability distribution function of wind speed at a installation site. - Abstract: In this paper, the boost in electrical energy production of horizontal-axis wind turbines with fixed rotor speed is studied. To achieve this, a new innovative algorithm is proposed and justified to predict a distribution of section pitch angle along wind turbine blades that corresponds to the maximum power extraction in the installation site. A code is developed based on the blade element momentum theory which incorporates different corrections such as the tip loss correction. This aerodynamic code is capable of accurately predicting the aerodynamics of horizontal-axis wind turbines

  5. 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...... 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...... trailing edge failure is very complex and can arise from manufacturing flaws, damages during transportation and erection as well as under general and extreme operational conditions. The focus in this study is put on the geometrical nonlinear buckling effect of the trailing edge under combined loading and...

  6. Survey of techniques for reduction of wind turbine blade trailing edge noise.

    Energy Technology Data Exchange (ETDEWEB)

    Barone, Matthew Franklin

    2011-08-01

    Aerodynamic noise from wind turbine rotors leads to constraints in both rotor design and turbine siting. The primary source of aerodynamic noise on wind turbine rotors is the interaction of turbulent boundary layers on the blades with the blade trailing edges. This report surveys concepts that have been proposed for trailing edge noise reduction, with emphasis on concepts that have been tested at either sub-scale or full-scale. These concepts include trailing edge serrations, low-noise airfoil designs, trailing edge brushes, and porous trailing edges. The demonstrated noise reductions of these concepts are cited, along with their impacts on aerodynamic performance. An assessment is made of future research opportunities in trailing edge noise reduction for wind turbine rotors.

  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. Integrated optimization analyses of aerodynamic/stealth characteristics of helicopter rotor based on surrogate model

    Directory of Open Access Journals (Sweden)

    Jiang Xiangwen

    2015-06-01

    Full Text Available Based on computational fluid dynamics (CFD method, electromagnetic high-frequency method and surrogate model optimization techniques, an integration design method about aerodynamic/stealth has been established for helicopter rotor. The developed integration design method is composed of three modules: integrated grids generation (the moving-embedded grids for CFD solver and the blade grids for radar cross section (RCS solver are generated by solving Poisson equations and folding approach, aerodynamic/stealth solver (the aerodynamic characteristics are simulated by CFD method based upon Navier–Stokes equations and Spalart–Allmaras (S–A turbulence model, and the stealth characteristics are calculated by using a panel edge method combining the method of physical optics (PO, equivalent currents (MEC and quasi-stationary (MQS, and integrated optimization analysis (based upon the surrogate model optimization technique with full factorial design (FFD and radial basis function (RBF, an integrated optimization analyses on aerodynamic/stealth characteristics of rotor are conducted. Firstly, the scattering characteristics of the rotor with different blade-tip swept and twist angles have been carried out, then time–frequency domain grayscale with strong scattering regions of rotor have been given. Meanwhile, the effects of swept-tip and twist angles on the aerodynamic characteristic of rotor have been performed. Furthermore, by choosing suitable object function and constraint condition, the compromised design about swept and twist combinations of rotor with high aerodynamic performances and low scattering characteristics has been given at last.

  9. Aerodynamically shaped vortex generators

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver; Velte, Clara Marika; Øye, Stig;

    2016-01-01

    An aerodynamically shaped vortex generator has been proposed, manufactured and tested in a wind tunnel. The effect on the overall performance when applied on a thick airfoil is an increased lift to drag ratio compared with standard vortex generators. Copyright © 2015 John Wiley & Sons, Ltd....

  10. Evaluation of techniques for computer modeling and real time control of a horizontal axis wind turbine blade

    Science.gov (United States)

    Wesenberg, Alan

    1995-05-01

    Wind power generating turbines operate under constant as well as rapidly changing conditions. With fixed pitch blades, many wind turbines are allowed to operate regardless of wind conditions as long as they are able to produce more electricity than it takes to get them started. However, the lifecycle of the turbine blades is often much shorter than expected because of the unsteady aerodynamic environment under which they rotate. Therefore, the National Renewable Energy Laboratory (NREL) has implemented a testing program to determine the aerodynamic conditions, and the frequency with which they occur, which cause the largest amount of fatigue on their variable pitch, three bladed downwind horizontal axis wind turbine (HAWT). Different techniques will be examined for analytically modeling the flow conditions with separation over a rotating turbine blade. Then, some different techniques for implementing a feedback control loop will be investigated to optimize the movement of the variable pitch blades on the NREL HAWT. The different methods analyzed will fall in the two-dimensional, incompressible area with most also being for steady state conditions. The final objective is to provide the reader with a background in dealing with the aerodynamic conditions surrounding a rotating wind turbine in an unsteady aerodynamic environment.

  11. Aerodynamic Simulation of the MEXICO Rotor

    International Nuclear Information System (INIS)

    CFD (Computational Fluid Dynamics) simulations are a very promising method for predicting the aerodynamic behavior of wind turbines in an inexpensive and accurate way. One of the major drawbacks of this method is the lack of validated models. As a consequence, the reliability of numerical results is often difficult to assess. The MEXICO project aimed at solving this problem by providing the project partners with high quality measurements of a 4.5 meters rotor diameter wind turbine operating under controlled conditions. The large measurement data-set allows the validation of all kind of aerodynamic models. This work summarizes our efforts for validating a CFD model based on the open source software OpenFoam. Both steady- state and time-accurate simulations have been performed with the Spalart-Allmaras turbulence model for several operating conditions. In this paper we will concentrate on axisymmetric inflow for 3 different wind speeds. The numerical results are compared with pressure distributions from several blade sections and PIV-flow data from the near wake region. In general, a reasonable agreement between measurements the and our simulations exists. Some discrepancies, which require further research, are also discussed

  12. Engineering Optimisation by Cuckoo Search

    CERN Document Server

    Yang, Xin-She

    2010-01-01

    A new metaheuristic optimisation algorithm, called Cuckoo Search (CS), was developed recently by Yang and Deb (2009). This paper presents a more extensive comparison study using some standard test functions and newly designed stochastic test functions. We then apply the CS algorithm to solve engineering design optimisation problems, including the design of springs and welded beam structures. The optimal solutions obtained by CS are far better than the best solutions obtained by an efficient particle swarm optimiser. We will discuss the unique search features used in CS and the implications for further research.

  13. Aerodynamic Investigation of Incidence Angle Effects in a Large Scale Transonic Turbine Cascade

    Science.gov (United States)

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

    2013-01-01

    Aerodynamic measurements showing the effects of large incidence angle variations on an HPT turbine blade set are presented. Measurements were made in NASA's Transonic Turbine Blade Cascade Facility which has been used in previous studies to acquire detailed aerodynamic and heat transfer measurements for CFD code validation. The current study supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50 percent speed range from takeoff to altitude cruise. This results in 50deg or more variations in VSPT blade incidence angles. The cascade facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Using existing blade geometry with previously acquired aerodynamic data, the tunnel was re-baselined and the new incidence angle range was exercised. Midspan exit total pressure and flow angle measurements were obtained at seven inlet flow angles. For each inlet angle, data were obtained at five flow conditions with inlet Reynolds numbers varying from 6.83×10(exp 5) to 0.85×10(exp 5) and two isentropic exit Mach numbers of 0.74 and 0.34. The midspan flowfield measurements were acquired using a three-hole pneumatic probe located in a survey plane 8.6 percent axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.

  14. Feasibility Study of a 3D CFD Solution for FSI Investigations on NREL 5MW Wind Turbine Blade

    OpenAIRE

    Bernardi, Giacomo

    2015-01-01

    With the increase in length of wind turbine blades flutter is becoming a potential design constrain, hence the interest in computational tools for fluid-structure interaction studies. The general approach to this problem makes use of simplified aerodynamic computational tools. Scope of this work is to investigate the outcomes of a 3D CFD simulation of a complete wind turbine blade, both in terms of numerical results and computational cost. The model studied is a 5MW theoretical wind turbine f...

  15. Torsional Stiffness Effects on the Dynamic Stability of a Horizontal Axis Wind Turbine Blade

    Directory of Open Access Journals (Sweden)

    Min-Soo Jeong

    2013-04-01

    Full Text Available Aeroelastic instability problems have become an increasingly important issue due to the increased use of larger horizontal axis wind turbines. To maintain these large structures in a stable manner, the blade design process should include studies on the dynamic stability of the wind turbine blade. Therefore, fluid-structure interaction analyses of the large-scaled wind turbine blade were performed with a focus on dynamic stability in this study. A finite element method based on the large deflection beam theory is used for structural analysis considering the geometric nonlinearities. For the stability analysis, a proposed aerodynamic approach based on Greenberg’s extension of Theodorsen’s strip theory and blade element momentum method were employed in conjunction with a structural model. The present methods proved to be valid for estimations of the aerodynamic responses and blade behavior compared with numerical results obtained in the previous studies. Additionally, torsional stiffness effects on the dynamic stability of the wind turbine blade were investigated. It is demonstrated that the damping is considerably influenced by variations of the torsional stiffness. Also, in normal operating conditions, the destabilizing phenomena were observed to occur with low torsional stiffness.

  16. 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

  17. Cooled snubber structure for turbine blades

    Science.gov (United States)

    Mayer, Clinton A; Campbell, Christian X; Whalley, Andrew; Marra, John J

    2014-04-01

    A turbine blade assembly in a turbine engine. The turbine blade assembly includes a turbine blade and a first snubber structure. The turbine blade includes an internal cooling passage containing cooling air. The first snubber structure extends outwardly from a sidewall of the turbine blade and includes a hollow interior portion that receives cooling air from the internal cooling passage of the turbine blade.

  18. A review of helicopter rotor blade tip shapes

    Science.gov (United States)

    Brocklehurst, A.; Barakos, G. N.

    2013-01-01

    A review of helicopter rotor blade tip design technology has been carried out with a view to undertaking subsequent computations to evaluate the performance of new tip designs. The review starts by briefly looking at (fixed) wing tip design concepts and the underlying fluid mechanics on which they are based in order to see if there is any carry-over of ideas on which improved tip design concepts might be based. Then, rotor blade tip shapes that have been used, or suggested for use, on past and present rotorcraft are examined to obtain a better understanding of the helicopter tip design problem. In parallel, the review traces the development of analysis tools to evaluate the performance of the rotor and blade tip design. It is clear that in the past, the designer relied heavily on classical aerodynamic knowledge, supplemented by experience and intuition, supported by wind tunnel and model rotor testing, and relatively low-order aerodynamic calculations. New rotor designs were, and still are the subject of intensive flight test verification. However, recent development of Computational Fluid Dynamics (CFD) now offers an opportunity to accurately predict the viscous, compressible flow-field in the tip region, and thus predict the performance of new rotor and tip designs, provided that the solver has adequate resolution, is able to handle all aspects of the helicopter problem, and sufficient computational resources are available to complete the design in a practical time-scale.

  19. Structural response of a fiber composite compressor fan blade airfoil

    Science.gov (United States)

    Chamis, C. C.; Minich, M. D.

    1975-01-01

    A theoretical investigation was performed to determine the structural response of a fiber composite airfoil typical of those encountered in high-tip speed compressor fan blades when subjected to load conditions anticipated in such applications. The analysis method consisted of composite mechanics embedded in pre- and post-processors coupled with NASTRAN. The load conditions examined include thermal due to aerodynamic heating, pressure due to aerodynamic forces, and centrifugal. Root reactions due to various load conditions, average composite and ply stresses, ply delaminations, and the fundamental modes and the corresponding reactions were investigated. The results show that the thermal and pressure stresses are negligible compared to those caused by the centrifugal forces. The core-shell concept for composite blades is an inefficient design and is sensitive to interply delaminations. The results are presented in graphical and tabular forms to illustrate the types and amount of data required for the analysis, and to provide quantitative data associated with the various responses which can be helpful in designing composite blades.

  20. Blade lock for a rotor disk and rotor blade assembly

    Science.gov (United States)

    Moore, Jerry H. (Inventor)

    1992-01-01

    A rotor disk 18 and rotor blade 26 assembly is disclosed having a blade lock 66 which retains the rotor blade against axial movement in an axially extending blade retention slot 58. Various construction details are developed which shield the dead rim region D.sub.d and shift at least a portion of the loads associated with the locking device from the dead rim. In one detailed embodiment, a projection 68 from the live rim D.sub.1 of the disk 18 is adapted by slots 86 to receive blade locks 66.

  1. 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.

  2. Engineering Optimisation by Cuckoo Search

    OpenAIRE

    Yang, Xin-She; Deb, Suash

    2010-01-01

    A new metaheuristic optimisation algorithm, called Cuckoo Search (CS), was developed recently by Yang and Deb (2009). This paper presents a more extensive comparison study using some standard test functions and newly designed stochastic test functions. We then apply the CS algorithm to solve engineering design optimisation problems, including the design of springs and welded beam structures. The optimal solutions obtained by CS are far better than the best solutions obtained by an efficient p...

  3. Numerical optimisation of an axial turbine; Numerische Optimierung einer Axialturbine

    Energy Technology Data Exchange (ETDEWEB)

    Welzel, B.

    1998-12-31

    The author presents a method for automatic shape optimisation of components with internal or external flow. The method combines a program for numerical calculation of frictional turbulent flow with an optimisation algorithm. Algorithms are a simplex search strategy and an evolution strategy. The shape of the component to be optimized is variable due to shape parameters modified by the algorithm. For each shape, a flow calculation is carried out on whose basis a functional value like performance, loss, lift or resistivity is calculated. For validation, the optimisation method is used in simple examples with known solutions. It is applied. It is applied to the components of a slow-running axial turbine. Components with accelerated and delayed rotationally symmetric flow and 2D blade profiles are optimized. [Deutsch] Es wird eine Methode zur automatischen Formoptimierung durchstroemter oder umstroemter Bauteile vorgestellt. Diese koppelt ein Programm zur numerischen Berechnung reibungsbehafteter turbulenter Stroemungen mit einem Optimierungsalgorithmus. Dabei kommen als Algorithmen eine Simplex-Suchstrategie und eine Evolutionsstrategie zum Einsatz. Die Form des zu optimierenden Koerpers ist durch Formparameter, die vom Algorithmus veraendert werden, variabel. Fuer jede Form wird eine Stroemungsberechnung durchgefuehrt und mit dieser ein Funktionswert wie Wirkungsgrad, Verlust, Auftrieb oder Widerstandskraft berechnet. Die Optimierungsmethode wird zur Validierung in einfachen Beispielen mit bekannter Loesung eingesetzt. Zur Anwendung kommt sie in den einzelnen Komponenten einer langsamlaeufigen Axialturbine. Es werden Bauteile mit beschleunigter und verzoegerter rotationssymmetrischer Stroemung und 2D-Schaufelprofile optimiert. (orig.)

  4. Wind turbine blade life-time assessment model for preventive planning of operation and maintenance

    DEFF Research Database (Denmark)

    Florian, Mihai; Sørensen, John Dalsgaard

    2014-01-01

    Out of the total wind turbine failure events, blade damage accounts for a substantial part, with some studies estimating it at around 23%. Current operation and maintenance (O&M) practices typically make use of corrective type maintenance as the basic approach, implying high costs for repair and......&M decisions for avoiding major failure events. The present paper presents a fracture mechanics based model for estimating the remaining life of a wind turbine blade, focusing on the crack propagation in the blades adhesive joints. A generic crack propagation model is built in Matlab based on a Paris law...... approach. The model is used within a risk-based maintenance decision framework to optimise maintenance planning for the blades lifetime....

  5. Vibrations of blades bunches

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    Brno: Brno University of Technology, 2014 - (Fuis, V.), s. 520-523 ISBN 978-80-214-4871-1. ISSN 1805-8248. [Engineering Mechanics 2014 /20./. Svratka (CZ), 12.05.2014-15.05.2014] Institutional support: RVO:61388998 Keywords : damping * dry friction * five-blades-bunch * harmonic excitation * response curve Subject RIV: BI - Acoustics

  6. 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....

  7. Numerical investigation of wind turbine and wind farm aerodynamics

    Science.gov (United States)

    Selvaraj, Suganthi

    A numerical method based on the solution of Reynolds Averaged Navier Stokes equations and actuator disk representation of turbine rotor is developed and implemented in the OpenFOAM software suite for aerodynamic analysis of horizontal axis wind turbines (HAWT). The method and the implementation are validated against the 1-D momentum theory, the blade element momentum theory and against experimental data. The model is used for analyzing aerodynamics of a novel dual rotor wind turbine concept and wind farms. Horizontal axis wind turbines suffer from aerodynamic inefficiencies in the blade root region (near the hub) due to several non-aerodynamic constraints (e.g., manufacturing, transportation, cost, etc.). A new dual-rotor wind turbine (DRWT) concept is proposed that aims at mitigating these losses. A DRWT is designed using an existing turbine rotor for the main rotor (Risoe turbine and NREL 5 MW turbine), while the secondary rotor is designed using a high lift to drag ratio airfoil (the DU 96 airfoil from TU Delft). The numerical aerodynamic analysis method developed as a part of this thesis is used to optimize the design. The new DRWT design gives an improvement of about 7% in aerodynamic efficiency over the single rotor turbine. Wind turbines are typically deployed in clusters called wind farms. HAWTs also suffer from aerodynamic losses in a wind farm due to interactions with wind turbine wakes. An interesting mesoscale meteorological phenomenon called "surface flow convergence" believed to be caused by wind turbine arrays is investigated using the numerical method developed here. This phenomenon is believed to be caused by the pressure gradient set up by wind turbines operating in close proximity in a farm. A conceptual/hypothetical wind farm simulation validates the hypothesis that a pressure gradient is setup in wind farms due to turbines and that it can cause flow veering of the order of 10 degrees. Simulations of a real wind farm (Story County) are also

  8. Optimisation of load control

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, P. [VTT Energy, Espoo (Finland)

    1998-08-01

    Electricity cannot be stored in large quantities. That is why the electricity supply and consumption are always almost equal in large power supply systems. If this balance were disturbed beyond stability, the system or a part of it would collapse until a new stable equilibrium is reached. The balance between supply and consumption is mainly maintained by controlling the power production, but also the electricity consumption or, in other words, the load is controlled. Controlling the load of the power supply system is important, if easily controllable power production capacity is limited. Temporary shortage of capacity causes high peaks in the energy price in the electricity market. Load control either reduces the electricity consumption during peak consumption and peak price or moves electricity consumption to some other time. The project Optimisation of Load Control is a part of the EDISON research program for distribution automation. The following areas were studied: Optimization of space heating and ventilation, when electricity price is time variable, load control model in power purchase optimization, optimization of direct load control sequences, interaction between load control optimization and power purchase optimization, literature on load control, optimization methods and field tests and response models of direct load control and the effects of the electricity market deregulation on load control. An overview of the main results is given in this chapter

  9. Optimisation of load control

    International Nuclear Information System (INIS)

    Electricity cannot be stored in large quantities. That is why the electricity supply and consumption are always almost equal in large power supply systems. If this balance were disturbed beyond stability, the system or a part of it would collapse until a new stable equilibrium is reached. The balance between supply and consumption is mainly maintained by controlling the power production, but also the electricity consumption or, in other words, the load is controlled. Controlling the load of the power supply system is important, if easily controllable power production capacity is limited. Temporary shortage of capacity causes high peaks in the energy price in the electricity market. Load control either reduces the electricity consumption during peak consumption and peak price or moves electricity consumption to some other time. The project Optimisation of Load Control is a part of the EDISON research program for distribution automation. The following areas were studied: Optimization of space heating and ventilation, when electricity price is time variable, load control model in power purchase optimization, optimization of direct load control sequences, interaction between load control optimization and power purchase optimization, literature on load control, optimization methods and field tests and response models of direct load control and the effects of the electricity market deregulation on load control. An overview of the main results is given in this chapter

  10. Computational electromagnetic-aerodynamics

    CERN Document Server

    Shang, Joseph J S

    2016-01-01

    Presents numerical algorithms, procedures, and techniques required to solve engineering problems relating to the interactions between electromagnetic fields, fluid flow, and interdisciplinary technology for aerodynamics, electromagnetics, chemical-physics kinetics, and plasmadynamics This book addresses modeling and simulation science and technology for studying ionized gas phenomena in engineering applications. Computational Electromagnetic-Aerodynamics is organized into ten chapters. Chapter one to three introduce the fundamental concepts of plasmadynamics, chemical-physics of ionization, classical magnetohydrodynamics, and their extensions to plasma-based flow control actuators, high-speed flows of interplanetary re-entry, and ion thrusters in space exploration. Chapter four to six explain numerical algorithms and procedures for solving Maxwell’s equation in the time domain for computational electromagnetics, plasma wave propagation, and the time-dependent c mpressible Navier-Stokes equation for aerodyn...

  11. BLADE sequences in transverse T2-weighted MR imaging of the cervical spine. Cut-off for artefacts?

    Energy Technology Data Exchange (ETDEWEB)

    Finkenzeller, T. [Hospital Nuremberg Sued (Germany). Inst. of Radiology and Neuroradiology; Wendl, C.M.; Stroszczynski, C.; Fellner, C. [University Hospital Regensburg (Germany). Inst. of Radiology; Lenhart, S. [Klinikum Weiden (Germany). Radiology and Neuroradiology; Schuierer, G. [Center of Neuroradiology, Regensburg (Germany). Inst. of Neuroradiology

    2015-02-15

    The BLADE (PROPELLER) technique reduces artefacts in imaging of the cervical spine in sagittal orientation, but till now failed to do so in axial orientation, because here it increased through plane CSF-flow artefacts, which spoiled the benefit of BLADE artefact reduction 'in plane'. The aim of this study was to compare a BLADE sequence with optimised measurement parameters in axial orientation to T2-TSE. Both sequences were compared in 58 patients with 31 discal, 16 bony and 11 spinal cord lesions. Image sharpness, reliability of spinal cord depiction, CSF flow artefacts and lesion detection were evaluated by 3 independent observers. Additionally the observers were asked which sequence they would prefer for diagnostic workup. Statistical evaluations were performed using sign and {sub X}2 test. BLADE was significantly superior concerning image sharpness, spinal cord depiction and overall lesion detection. BLADE was rated better for most pathologies, for bony lesions the differences compared with TSE were statistically significant. Regarding CSF-flow artefacts both sequences showed no difference. All readers preferred BLADE in side by side reading. An optimised axial T2 BLADE sequence decreases the problems of increased through plane CSF-flow artefacts in this orientation. By reducing various other artefacts it yields better image quality and has the potential to reduce the number of non-diagnostic examinations especially in uncooperative patients.

  12. BLADE sequences in transverse T2-weighted MR imaging of the cervical spine. Cut-off for artefacts?

    International Nuclear Information System (INIS)

    The BLADE (PROPELLER) technique reduces artefacts in imaging of the cervical spine in sagittal orientation, but till now failed to do so in axial orientation, because here it increased through plane CSF-flow artefacts, which spoiled the benefit of BLADE artefact reduction 'in plane'. The aim of this study was to compare a BLADE sequence with optimised measurement parameters in axial orientation to T2-TSE. Both sequences were compared in 58 patients with 31 discal, 16 bony and 11 spinal cord lesions. Image sharpness, reliability of spinal cord depiction, CSF flow artefacts and lesion detection were evaluated by 3 independent observers. Additionally the observers were asked which sequence they would prefer for diagnostic workup. Statistical evaluations were performed using sign and X2 test. BLADE was significantly superior concerning image sharpness, spinal cord depiction and overall lesion detection. BLADE was rated better for most pathologies, for bony lesions the differences compared with TSE were statistically significant. Regarding CSF-flow artefacts both sequences showed no difference. All readers preferred BLADE in side by side reading. An optimised axial T2 BLADE sequence decreases the problems of increased through plane CSF-flow artefacts in this orientation. By reducing various other artefacts it yields better image quality and has the potential to reduce the number of non-diagnostic examinations especially in uncooperative patients.

  13. Small, high pressure ratio compressor: Aerodynamic and mechanical design

    Science.gov (United States)

    Bryce, C. A.; Erwin, J. R.; Perrone, G. L.; Nelson, E. L.; Tu, R. K.; Bosco, A.

    1973-01-01

    The Small, High-Pressure-Ratio Compressor Program was directed toward the analysis, design, and fabrication of a centrifugal compressor providing a 6:1 pressure ratio and an airflow rate of 2.0 pounds per second. The program consists of preliminary design, detailed areodynamic design, mechanical design, and mechanical acceptance tests. The preliminary design evaluate radial- and backward-curved blades, tandem bladed impellers, impeller-and diffuser-passage boundary-layer control, and vane, pipe, and multiple-stage diffusers. Based on this evaluation, a configuration was selected for detailed aerodynamic and mechanical design. Mechanical acceptance test was performed to demonstrate that mechanical design objectives of the research package were met.

  14. Aerodynamic performance of wind turbine under different yaw angles

    DEFF Research Database (Denmark)

    Shi, Yali; Zuo, Hongmei; Yang, Hua;

    2015-01-01

    is set as 5×10-6 m to ensure the first dimensionless size near the wall Y+<0.5 on the wall, the 2 numbers of grids are determined by the error of axial load on the airfoil in the 60% section of blades, which respectively are 6 572 451 and 2 961 385. The aerodynamic performance of models under rated...... are drawn. The distributions of pressure coefficients along the airfoil chord in different blade sections calculated by CFD method are in good agreement with the experimental measurements, and the error on the suction surface of airfoil is mainly caused by stall separation occurring on the pressure...... surface of airfoil. With the increasing of yaw angle, the pressure coefficients of the suction side are increasing and the location of minimum pressure coefficient moves to airfoil trailing edge slightly. For the pressure side, the pressure coefficients increase at first and then decrease, and the...

  15. Aerodynamic performance prediction of Darrieus-type wind turbines

    Directory of Open Access Journals (Sweden)

    Ion NILĂ

    2010-06-01

    Full Text Available The prediction of Darrieus wind turbine aerodynamic performances provides the necessarydesign and operational data base related to the wind potential. In this sense it provides the type ofturbine suitable to the area where it is to be installed. Two calculation methods are analyzed for arotor with straight blades. The first one is a global method that allows an assessment of the turbinenominal power by a brief calculation. This method leads to an overestimation of performances. Thesecond is the calculation method of the gust factor and momentum which deals with the pale as beingcomposed of different elements that don’t influence each other. This method, developed based on thetheory of the turbine blades, leads to values close to the statistical data obtained experimentally. Thevalues obtained by the calculation method of gust factor - momentum led to the concept of a Darrieusturbine, which will be tested for different wind values in the INCAS subsonic wind tunnel.

  16. Aerodynamic Limits on Large Civil Tiltrotor Sizing and Efficiency

    Science.gov (United States)

    Acree, C W., Jr.

    2014-01-01

    The NASA Large Civil Tiltrotor (2nd generation, or LCTR2) has been the reference design for avariety of NASA studies of design optimization, engine and gearbox technology, handling qualities, andother areas, with contributions from NASA Ames, Glenn and Langley Centers, plus academic and industrystudies. Ongoing work includes airfoil design, 3D blade optimization, engine technology studies, andwingrotor aerodynamic interference. The proposed paper will bring the design up to date with the latestresults of such studies, then explore the limits of what aerodynamic improvements might hope toaccomplish. The purpose is two-fold: 1) determine where future technology studies might have the greatestpayoff, and 2) establish a stronger basis of comparison for studies of other vehicle configurations andmissions.

  17. BWR control blade replacement strategies

    International Nuclear Information System (INIS)

    The reactivity control elements in a BWR, the control blades, perform three significant functions: provide shutdown margin during normal and accident operating conditions; provide overall core reactivity control; and provide axial power shaping control. As such, the blades are exposed to the core's neutron flux, resulting in irradiation of blade structural and absorber materials. Since the absorber depletes with time (if B4C is used, it also swells) and the structural components undergo various degradation mechanisms (e.g., embrittlement, corrosion), the blades have limits on their operational lifetimes. Consequently, BWR utilities have implemented strategies that aim to maximize blade lifetimes while balancing operational costs, such as extending a refuelling outage to shuffle high exposure blades. This paper examines the blade replacement strategies used by BWR utilities operating in US, Europe and Asia by assembling information related to: the utility's specific blade replacement strategy; the impact the newer blade designs and changes in core operating mode were having on those strategies; the mechanical and nuclear limits that determined those strategies; the methods employed to ensure that lifetime limits were not exceeded during operation; and blade designs used (current and replacement blades). (author)

  18. Aerodynamic structures and processes in rotationally augmented flow fields

    DEFF Research Database (Denmark)

    Schreck, S.J.; Sørensen, Niels N.; Robinson, M.C.

    2007-01-01

    reliably identify and track pertinent features in the rotating blade boundary layer topology as they evolved in response to varying wind speed. Subsequently, boundary layer state was linked to above-surface flow field structure and used to deduce mechanisms; underlying augmented aerodynamic force....... Experimental measurements consisted of surface pressure data statistics used to infer sectional boundary layer state and to quantify normal force levels. Computed predictions included high-resolution boundary layer topologies and detailed above-surface flow field structures. This synergy was exploited to...

  19. An aerodynamic noise propagation model for wind turbines

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Sørensen, Jens Nørkær; Shen, Wen Zhong

    2005-01-01

    temperature and airflow. At a given receiver point, the sound pressure is corrected by taking into account these propagation effects. As an overall assumption, the noise field generated by the wind turbine is simplified as a point source placed at the hub height of the wind turbine. This assumtion......A model based on 2-D sound ray theory for aerodynamic noise propagation from wind turbine rotating blades is introduced. The model includes attenuation factors from geometric spreading, sound directivity of source, air absorption, ground deflection and reflection, as well as effects from...

  20. Numerical analysis of aerodynamic noise radiated from cross flow fan

    Institute of Scientific and Technical Information of China (English)

    Anbang CHEN; Song LI; Dongtao HUANG

    2008-01-01

    The flow field in a cross flow fan was simulated by solving the 2-D unsteady Reynolds-averaged Navier-Stokes equations. The calculated pressure fluctuations of the blades, the vortex wall, and the rear wall were then used as noise sources to calculate the sound field. The Ffowcs Williams-Hawkings (FW-H) equation was employed to predict the noise field caused by these sources. The predictions show that the rear wall and the vortex wall sources contribute significantly to the total noise and that both the predicted aerodynamic perform-ance and noise agree well with the experimental results.

  1. 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).

  2. Numerical simulation and Hopf bifurcation of flutter-type oscillation of two-dimensional blade

    International Nuclear Information System (INIS)

    A numerical method is proposed to simulate the Flutter-type oscillation of the two-dimensional blades in a flow with low speed. The finite element method is used to solve numerically the Laplace equation, and then the aerodynamic forces can be obtained using the unsteady Bernoulli equation. A two-degree-of-freedom dynamic model is introduced to describe the blade oscillation, and Runge-Kutta method is applied to solve the equation of motion. The coupled fields can be solved alternately, and the oscillation orbit of the two-dimensional blade can be obtained. Furthermore, the results are presented in phase plane and studied based on Hopf bifurcation. The influence of the flow velocity on the blade flutter is studied, and it can be concluded that the appearance of flutter-type oscillation is the result of the occurrence of Hopf bifurcation, as the flow velocity increases

  3. Comparison of the pressure distribution of a wind turbine blade based on field experiment and CFD

    International Nuclear Information System (INIS)

    Field experiment and numerical simulation are performed on a 33 kW horizontal axis wind turbine. The distribution of pressure is gathered by disposed 191 taped pressure sensors span-ward on seven particular sections of a blade. And the parameters of experimental condition of inflow and operation condition of the wind turbine are obtained at the same time. And then, the three-dimensional Reynolds averaged incompressible Navier-Stokes equations and the RNG κ-ε turbulence model are used to study the aerodynamic characteristics of the wind turbine. The numerical method is proved to be more effective by contrasting the numerical results to the field experimental data. For the calculation results of the blade pressure, the closer to the root of the blade the more consistent to the values of the experiment. A greater differential is shown at the leading edge than the trailing edge. The pressure distribution contours of the blade surface are obtained too

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

    OpenAIRE

    Eduard Dyachuk; Anders Goude

    2015-01-01

    Cyclic blade motion during operation of vertical axis wind turbines (VAWTs) imposes challenges on the simulations models of the aerodynamics of VAWTs. A two-dimensional vortex model is validated against the new experimental data on a 12-kW straight-bladed VAWT, which is operated at an open site. The results on the normal force on one blade are analyzed. The model is assessed against the measured data in the wide range of tip speed ratios: from 1.8 to 4.6. The predicted results within one revo...

  5. Rotor blade vortex interaction noise

    Science.gov (United States)

    Yu, Yung H.

    2000-02-01

    Blade-vortex interaction noise-generated by helicopter main rotor blades is one of the most severe noise problems and is very important both in military applications and community acceptance of rotorcraft. Research over the decades has substantially improved physical understanding of noise-generating mechanisms, and various design concepts have been investigated to control noise radiation using advanced blade planform shapes and active blade control techniques. The important parameters to control rotor blade-vortex interaction noise and vibration have been identified: blade tip vortex structures and its trajectory, blade aeroelastic deformation, and airloads. Several blade tip design concepts have been investigated for diffusing tip vortices and also for reducing noise. However, these tip shapes have not been able to substantially reduce blade-vortex interaction noise without degradation of rotor performance. Meanwhile, blade root control techniques, such as higher-harmonic pitch control (HHC) and individual blade control (IBC) concepts, have been extensively investigated for noise and vibration reduction. The HHC technique has proved the substantial blade-vortex interaction noise reduction, up to 6 dB, while vibration and low-frequency noise have been increased. Tests with IBC techniques have shown the simultaneous reduction of rotor noise and vibratory loads with 2/rev pitch control inputs. Recently, active blade control concepts with smart structures have been investigated with the emphasis on active blade twist and trailing edge flap. Smart structures technologies are very promising, but further advancements are needed to meet all the requirements of rotorcraft applications in frequency, force, and displacement.

  6. Optimisation multidisciplinaire de pales d'hélice d'avion

    OpenAIRE

    Marinus, Benoît

    2011-01-01

    Open rotors are known to have significant advantages in terms of propulsive efficiency. These advantages translate directly in reduced fuel burn so that they nowadays benefit from a surge of interest. At the same time, recent advances in numerical simulations make the application of multidisciplinary optimization for the demanding design of transonic propeller blades, an affordable option. Therefore, an optimization method in which the performance objectives of aerodynamics, aeroacoustics and...

  7. Development and application of a dynamic stall model for rotating wind turbine blades

    International Nuclear Information System (INIS)

    In unsteady conditions of wind turbines, both the dynamic stall phenomenon and the three-dimensional (3D) rotational effect affect the rotor aerodynamics. The dynamic stall mechanism for rotating wind turbine blades is first investigated. Through the comparison of the aerodynamic data between the rotating blade and the two-dimensional (2D) airfoil, the normal force slope in the attached flow and the separation point expression in the separated flow are modified in the Beddoes-Leishman (B-L) dynamic stall model for rotating NREL wind turbine blades. The modified model is validated by the comparison between the calculation results and the experimental results of the lift and drag coefficients at different radial positions. Both the hysteresis loop shapes and the calculation values are closer to the experiment than the 2D dynamic stall model. The present dynamic stall model is then coupled to a free vortex wake model. The coupled model is used to calculate the unsteady blade aerodynamic loads and the low speed shaft torque of the NREL wind turbine in a yawed condition. The accuracy is greatly improved by the corrections presented in the paper

  8. Conjectural bifurcation analysis of the contact-induced vibratory response of an aircraft engine blade

    Science.gov (United States)

    Batailly, Alain; Legrand, Mathias; Millecamps, Antoine; Garcin, François

    2015-07-01

    This paper deals with the numerical investigation of the unilateral contact-induced dynamics of a turbomachine blade rotating within a perfectly rigid yet distorted casing. This investigation is motivated by unelucidated vibratory behaviours observed experimentally. The simulations are based on an in-house time-marching strategy incorporating Lagrange multipliers for the unilateral contact treatment, as well as centrifugal stiffening and abradable coating removal. Significant extensions are proposed through the implementation of (1) aerodynamic loading on the blade and (2) post-processing techniques involving the empirical mode decomposition which provides fruitful insights on important transient phenomena. A thorough bifurcation analysis with and without aerodynamic loading highlights the existence of flip bifurcations with period-doubling and period-halving sequences over a broad angular speed range. Numerical simulations with external aerodynamic loading yield quasi-periodic and likely to be chaotic motions that could not be observed under vacuum. The proposed numerical investigations underline the key role of the aerodynamic loading in the blade dynamics and suggest that unexplained experimental vibratory behaviours are related to the vacuum conditions of the experiment.

  9. Optimization of helicopter rotor blade design for minimum vibration

    Science.gov (United States)

    Davis, M. W.

    1984-01-01

    The optimization approach discussed is part of an ongoing effort to develop a general automated procedure for rotor blade design. This procedure can be used to determine the necessary geometric, structural, and material properties of a rotor system to achieve desired objectives relating to vibration, stress, and aerodynamic performance. The approach used for helicopter vibration is emphasized. Based on analytical studies performed at the United Technologies Research Center (UTRC), a simplified vibration analysis was developed to be used in conjunction with a forced response analysis in the optimization process. This simplified analysis improves the efficiency of the design process significantly. Results of applying this approach to the design of an existing rotor blade model are presented.

  10. Design Optimization of a Centrifugal Fan with Splitter Blades

    Science.gov (United States)

    Heo, Man-Woong; Kim, Jin-Hyuk; Kim, Kwang-Yong

    2015-05-01

    Multi-objective optimization of a centrifugal fan with additionally installed splitter blades was performed to simultaneously maximize the efficiency and pressure rise using three-dimensional Reynolds-averaged Navier-Stokes equations and hybrid multi-objective evolutionary algorithm. Two design variables defining the location of splitter, and the height ratio between inlet and outlet of impeller were selected for the optimization. In addition, the aerodynamic characteristics of the centrifugal fan were investigated with the variation of design variables in the design space. Latin hypercube sampling was used to select the training points, and response surface approximation models were constructed as surrogate models of the objective functions. With the optimization, both the efficiency and pressure rise of the centrifugal fan with splitter blades were improved considerably compared to the reference model.

  11. Aerodynamic data of space vehicles

    CERN Document Server

    Weiland, Claus

    2014-01-01

    The capacity and quality of the atmospheric flight performance of space flight vehicles is characterized by their aerodynamic data bases. A complete aerodynamic data base would encompass the coefficients of the static longitudinal and lateral motions and the related dynamic coefficients. In this book the aerodynamics of 27 vehicles are considered. Only a few of them did really fly. Therefore the aerodynamic data bases are often not complete, in particular when the projects or programs were more or less abruptly stopped, often due to political decisions. Configurational design studies or the development of demonstrators usually happen with reduced or incomplete aerodynamic data sets. Therefore some data sets base just on the application of one of the following tools: semi-empirical design methods, wind tunnel tests, numerical simulations. In so far a high percentage of the data presented is incomplete and would have to be verified. Flight mechanics needs the aerodynamic coefficients as function of a lot of var...

  12. Numerical investigation of turbulent flow past a four-bladed helicopter rotor using k - ω SST model

    International Nuclear Information System (INIS)

    In a previous study of the laminar flow over a four-bladed helicopter rotor, abnormal Cp distributions were observed on the upper surfaces of the blades. To address this problem, the aerodynamic performance of the same rotor is investigated using the k - ω SST turbulence model, as contained in the WIND code. The rotor is configured as a Chimera moving grid in a quasi-steady flow field. The rotor rotation schedule and the blade twisting are implemented as specified in the wind tunnel testing of a RoBin generic helicopter. More realistic Cp distributions on the blade surfaces are thus obtained. The aerodynamic load distributions in the radial direction of the rotor plane are generated by integrating the pressure on each blade surfaces along the blade chordwise direction. The analyses of these load distributions in the azmuthal direction provide a critical insight into the rotor model, which is based on the actuator-disc assumption. Also, some preliminary results for the flow past a full helicopter configuration, including the rotor and the RoBin fuselage, are presented. The current paper demonstrates the Chimera grid topologies and the Chimera grid generation technique for both blade and fuselage configuration. This would provide a powerful tool to simulate flow past an entire helicopter and to study the rotor-fuselage flow interaction. (author)

  13. Investigation and Optimization of Blade Tip Winglets Using an Implicit Free Wake Vortex Method

    International Nuclear Information System (INIS)

    Novel outer-blade geometries such as tip winglets can increase the aerodynamic power that can be extracted from the wind by tailoring the relative position and strengths of trailed vorticity. This design space is explored using both parameter studies and gradient-based optimization, with the aerodynamic analysis carried out using LibAero, a free wake vortex-based code introduced in previous work. The starting design is the NREL 5MW reference turbine, which allows comparison of the aerodynamic simulation for the unmodified blade with other codes. The code uses a Prandtl-Weissinger lifting line model to represent the blade, and vortex filaments as the flow elements. A fast multipole method is implemented to accelerate the influence calculations and reduce the computational cost. This results in higher fidelity aerodynamic simulations that can capture the effects of novel geometries while maintaining sufficiently fast run-times (on the order of an hour) to allow the use of optimization. Gradients of the objective function with respect to design variables are calculated using the complex step method which is accurate and efficient. Since the vortex structure behind the rotor is being resolved in detail, insight is also gained into the mechanisms by which these new blade designs affect performance. It is found that adding winglets can increase the power extracted from the wind by around 2%, with a similar increase in thrust. It is also possible to create a winglet that slightly lowers the thrust while maintaining very similar power compared to the standard straight blade

  14. Numerical Simulation of Wind Turbine Blade-Tower Interaction

    Institute of Scientific and Technical Information of China (English)

    Qiang Wang; Hu Zhou; Decheng Wan

    2012-01-01

    Numerical simulations of wind turbine blade-tower interaction by using the open source OpenFOAM tools coupled with arbitrary mesh interface (AMI) method were presented.The governing equations were the unsteady Reynolds-averaged Navier-Stokes (PANS) which were solved by the pimpleDyMFoam solver,and the AMI method was employed to handle mesh movements.The National Renewable Energy Laboratory (NREL) phase Ⅵ wind turbine in upwind configuration was selected for numerical tests with different incoming wind speeds (5,10,15,and 25 m/s) at a fixed blade pitch and constant rotational speed.Detailed numerical results of vortex structure,time histories of thrust,and pressure distribution on the blade and tower were presented.The findings show that the wind turbine tower has little effect on the whole aerodynamic performance of an upwind wind turbine,while the rotating rotor will induce an obvious cyclic drop in the front pressure of the tower.Also,strong interaction of blade tip vortices with separation from the tower was observed.

  15. 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.

  16. LP compressor blade vibration characteristics at starting conditions of a 100 MW heavy-duty gas turbine

    International Nuclear Information System (INIS)

    In this paper are presented the blade vibration characteristics at the starting conditions of the low pressure multistage axial compressor of heavy-duty 100 MW gas turbine. Vibration data have been collected through strain gauges during aerodynamic tests of the model compressor. The influences of operating modes at the starting conditions are investigated upon the compressor blade vibrations. The exciting mechanisms and features of blade vibrations are investigated at the surge, rotating stall, and buffeting flutter. The influences of operating modes upon blade dynamic stresses are investigated for the first and second stages. It is shown that a high dynamic stress peak of 120 MPa can occur in the first stage blades due to resonances with stall cell excitations or with inlet strut wake excitations at the stalled conditions

  17. LP compressor blade vibration characteristics at starting conditions of a 100 MW heavy-duty gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    Lee, An Sung [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of); Vedichtchev, Alexandre F. [Leningradsky Metallichesky Zavod, Petersburg (Russian Federation)

    2004-06-01

    In this paper are presented the blade vibration characteristics at the starting conditions of the low pressure multistage axial compressor of heavy-duty 100 MW gas turbine. Vibration data have been collected through strain gauges during aerodynamic tests of the model compressor. The influences of operating modes at the starting conditions are investigated upon the compressor blade vibrations. The exciting mechanisms and features of blade vibrations are investigated at the surge, rotating stall, and buffeting flutter. The influences of operating modes upon blade dynamic stresses are investigated for the first and second stages. It is shown that a high dynamic stress peak of 120 MPa can occur in the first stage blades due to resonances with stall cell excitations or with inlet strut wake excitations at the stalled conditions.

  18. AM1, a high-performance superalloy for single crystal turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Bachelet, E.; Lamanthe, G. (Societe Nationale d' Etude et de Construction de Moteurs d' Aviation (SNECMA), 75 - Paris (France))

    1992-05-01

    SNECMA has developed a nickel-based superalloy for the manufacture of high-performance turbine blades. The authors recall the basic principles governing the behaviour of superalloys and the steady progress made in producing turbine blades. They go on to explain the approaches used for analysis, production and heat treatment leading to the specification of AM and the optimisation of the alloy's microstructure. They describe its mechanical properties including tensile behaviour and toughness, its resistance to creep, to thermal and low cycle fatigue, and to environmental constraints. (author). 11 figs., 3 tabs.

  19. Experimental Blade Research

    DEFF Research Database (Denmark)

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

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

  20. Damage detection method for wind turbine blades based on dynamics analysis and mode shape difference curvature information

    Science.gov (United States)

    Wang, Yanfeng; Liang, Ming; Xiang, Jiawei

    2014-10-01

    Blades are among the key components of wind turbines. Blade damage is one of the most common types of structural defects and can cause catastrophic structural failure. Therefore, it is highly desirable to detect and diagnose blade damage as early as possible. In this paper, we propose a method for blade damage detection and diagnosis. This method incorporates finite element method (FEM) for dynamics analysis (modal analysis and response analysis) and the mode shape difference curvature (MSDC) information for damage detection/diagnosis. Finite element models of wind turbine blades have been built and modified via frequency comparison with experimental data and the formula for the model updating technique. Our numerical simulation results have demonstrated that the proposed technique can detect the spatial locations of damages for wind turbine blades. Changes in natural frequencies and modes for smaller size blades with damage are found to occur at lower frequencies and lower modes than in the larger sized blade case. The relationship between modal parameters and damage information (location, size) is very complicated especially for larger size blades. Moreover, structure and dynamic characters for larger size blades are different from those for smaller sized blades. Therefore, dynamic response analysis for a larger sized wind turbine blade with a multi-layer composite material based on aerodynamic loads’ (including lift forces and drag forces) calculation has been carried out and improved the efficiency and precision to damage detection by combining (MSDC) information. This method provides a low cost and efficient non-destructive tool for wind turbine blade condition monitoring.

  1. Blade Vibration Measurement System

    Science.gov (United States)

    Platt, Michael J.

    2014-01-01

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

  2. TEM turbulence optimisation in stellarators

    CERN Document Server

    Proll, J H E; Xanthopoulos, P; Lazerson, S A; Faber, B J

    2015-01-01

    With the advent of neoclassically optimised stellarators, optimising stellarators for turbulent transport is an important next step. The reduction of ion-temperature-gradient-driven turbulence has been achieved via shaping of the magnetic field, and the reduction of trapped-electron mode (TEM) turbulence is adressed in the present paper. Recent analytical and numerical findings suggest TEMs are stabilised when a large fraction of trapped particles experiences favourable bounce-averaged curvature. This is the case for example in Wendelstein 7-X [C.D. Beidler $\\textit{et al}$ Fusion Technology $\\bf{17}$, 148 (1990)] and other Helias-type stellarators. Using this knowledge, a proxy function was designed to estimate the TEM dynamics, allowing optimal configurations for TEM stability to be determined with the STELLOPT [D.A. Spong $\\textit{et al}$ Nucl. Fusion $\\bf{41}$, 711 (2001)] code without extensive turbulence simulations. A first proof-of-principle optimised equilibrium stemming from the TEM-dominated stella...

  3. Calculation and characteristics analysis of blade pitch loads for large scale wind turbines

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Based on the electric pitch system of large scale horizontal-axis wind turbines,the blade pitch loads coming mainly from centrifugal force,aerodynamic force and gravity are analyzed,and the calculation models for them are established in this paper.For illustration,a 1.2 MW wind turbine is introduced as a practical sample,and its blade pitch loads from centrifugal force,aerodynamic force and gravity are calculated and analyzed separately and synthetically.The research results showed that in the process of rotor rotating 360o,the fluctuation of blade pitch loads is similar to cosine curve when the rotor rotational speed,in-flow wind speed and pitch angle are constant.Furthermore,the amplitude of blade pitch load presents quite a difference at a different pitch angle.The ways of calculation for blade pitch loads are of the universality,and are helpful for further research of the individual pitch control system.

  4. An aeroelastic analysis of helicopter rotor blades incorporating piezoelectric fiber composite twist actuation

    Science.gov (United States)

    Wilkie, W. Keats; Park, K. C.

    1996-01-01

    A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consist of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for numerical integration. The twist actuation responses for three conceptual full-scale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.

  5. Aeroelastic Analysis of Helicopter Rotor Blades Incorporating Anisotropic Piezoelectric Twist Actuation

    Science.gov (United States)

    Wilkie, W. Keats; Belvin, W. Keith; Park, K. C.

    1996-01-01

    A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consists of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for dynamics simulation using numerical integration. The twist actuation responses for three conceptual fullscale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.

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

    International Nuclear Information System (INIS)

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

  7. Aerodynamics of wind turbines

    CERN Document Server

    Hansen, Martin O L

    2015-01-01

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design a classical pitch and torque regulator to control rotational speed and power, while the section on structural dynamics has been extended with a simplified mechanical system explaining the phenomena of forward and backward whirling modes. Readers will also benefit from a new chapter on Vertical Axis W

  8. Development of an active twist rotor blade with distributed actuation and orthotropic material

    Science.gov (United States)

    Wierach, Peter; Riemenschneider, Johannes; Keye, Stefan

    2005-05-01

    Individual blade control (IBC) as well as higher harmonic control (HHC) for helicopter rotors promises to be a method to increase flight performance and to reduce vibration and noise. For those controls, an additional twist actuation of the rotor blade is needed. The developed concept comprises the implementation of distributed piezoelectric actuation into the rotor blade skin. In order to maximize the twist within given constraints, as torsional rigidity and given actuator design, the concept takes advantage of an orthotropic rotor blade skin. That way, a combination of shear actuation with orthotropic coupling generates more twist than each one of these effects alone. Previous approaches with distributed actuation used actuators operating in +/-45° direction with quasi-isotropic composites. A FE-Model of the blade was developed and validated using a simplified demonstrator. The objective of this study was to identify the effects of various geometric and material parameters to optimize the active twist performance of the blades. The whole development was embedded in an iterative process followed by an objective assessment. For this purpose a detailed structural model on the basis of the BO105 model rotor blade was developed, to predict the performance with respect to rotor dynamics, stability, aerodynamics and acoustics. Rotor dynamic simulations provided an initial overview of the active twist rotor performance. In comparison to the BO105 baseline rotor a noise reduction of 3 dB was predicted for an active twist of 0.8° at the blade tip. Additionally, a power reduction of 2.3% at 87m/s based on a 2.5 to BO105 was computed. A demonstrator blade with a rotor radius of 2m has been designed and manufactured. This blade will be tested to prove, that the calculated maximum twist can also be achieved under centrifugal loads.

  9. Snubber assembly for turbine blades

    Science.gov (United States)

    Marra, John J

    2013-09-03

    A snubber associated with a rotatable turbine blade in a turbine engine, the turbine blade including a pressure sidewall and a suction sidewall opposed from the pressure wall. The snubber assembly includes a first snubber structure associated with the pressure sidewall of the turbine blade, a second snubber structure associated with the suction sidewall of the turbine blade, and a support structure. The support structure extends through the blade and is rigidly coupled at a first end portion thereof to the first snubber structure and at a second end portion thereof to the second snubber structure. Centrifugal loads exerted by the first and second snubber structures caused by rotation thereof during operation of the engine are at least partially transferred to the support structure, such that centrifugal loads exerted on the pressure and suctions sidewalls of the turbine blade by the first and second snubber structures are reduced.

  10. Some practical issues in the computational design of airfoils for the helicopter main rotor blades

    Directory of Open Access Journals (Sweden)

    Kostić Ivan

    2004-01-01

    Full Text Available Very important requirement for the helicopter rotor airfoils is zero, or nearly zero moment coefficient about the aerodynamic center. Unlike the old technologies used for metal blades, modern production involving application of plastic composites has imposed the necessity of adding a flat tab extension to the blade trailing edge, thus changing the original airfoil shape. Using computer program TRANPRO, the author has developed and verified an algorithm for numerical analysis in this design stage, applied it on asymmetrical reflex camber airfoils, determined the influence of angular tab positioning on the moment coefficient value and redesigned some existing airfoils to include properly positioned tabs that satisfy very low moment coefficient requirement. .

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

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Sørensen, Niels N.; Schreck, Scott;

    2016-01-01

    reduced order dynamic stall model that uses rotationally augmented steady-state polars obtained from steady Phase VI experimental sequences, instead of the traditional two-dimensional, non-rotating data. The aim of this work is twofold. First, the blade loads estimated by the DDES simulations are compared...... qualitative agreement between the model and the experimental data in many cases, which suggests that the current two-dimensional dynamic stall model as used in blade element momentum-based aeroelastic codes may provide a reasonably accurate representation of three-dimensional rotor aerodynamics when used in...

  12. 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.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    frequency and the rotational forcing, the tower mode frequency is lowered with a modified tower stiffness distributions. The loads caused by the aerodynamic unbalance are instead addressed by introducing a teetering hub configuration. The load alleviation potential of the teetering hub, and the required...... study on an alternative downwind two-bladed rotor configuration. The study is based on a model representative of next generation multi-MW wind turbines: the DTU 10-MW Reference Wind Turbine (RWT). As a first design iteration, the aerodynamic characteristics of the original rotor are maintained, and the...

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

    DEFF Research Database (Denmark)

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

    frequency and the rotational forcing, the tower mode frequency is lowered with a modified tower stiffness distributions. The loads caused by the aerodynamic unbalance are instead addressed by introducing a teetering hub configuration. The load alleviation potential of the teetering hub, and the required...... study on an alternative downwind two-bladed rotor configuration. The study is based on a model representative of next generation multi-MW wind turbines: the DTU 10-MW Reference Wind Turbine (RWT). As a first design iteration, the aerodynamic characteristics of the original rotor are maintained, and the...

  15. Constructal blade shape in nanofluids

    OpenAIRE

    Bai Chao; Wang Liqiu

    2011-01-01

    Abstract Blade configuration of nanofluids has been proven to perform much better than dispersed configuration for some heat conduction systems. The analytical analysis and numerical calculation are made for the cylinder--shaped and regular-rectangular-prism--shaped building blocks of the blade-configured heat conduction systems (using nanofluids as the heat conduction media) to find the optimal cross-sectional shape for the nanoparticle blade under the same composing materials, composition r...

  16. Aerodynamics of sports balls

    Science.gov (United States)

    Mehta, R. D.

    Research data on the aerodynamic behavior of baseballs and cricket and golf balls are summarized. Cricket balls and baseballs are roughly the same size and mass but have different stitch patterns. Both are thrown to follow paths that avoid a batter's swing, paths that can curve if aerodynamic forces on the balls' surfaces are asymmetric. Smoke tracer wind tunnel tests and pressure taps have revealed that the unbalanced side forces are induced by tripping the boundary layer on the seam side and producing turbulence. More particularly, the greater pressures are perpendicular to the seam plane and only appear when the balls travel at velocities high enough so that the roughness length matches the seam heigh. The side forces, once tripped, will increase with spin velocity up to a cut-off point. The enhanced lift coefficient is produced by the Magnus effect. The more complex stitching on a baseball permits greater variations in the flight path curve and, in the case of a knuckleball, the unsteady flow effects. For golf balls, the dimples trip the boundary layer and the high spin rate produces a lift coefficient maximum of 0.5, compared to a baseball's maximum of 0.3. Thus, a golf ball travels far enough for gravitational forces to become important.

  17. Implementation of a Helicopter Flight Simulator with Individual Blade Control

    Science.gov (United States)

    Zinchiak, Andrew G.

    2011-12-01

    Nearly all modern helicopters are designed with a swashplate-based system for control of the main rotor blades. However, the swashplate-based approach does not provide the level of redundancy necessary to cope with abnormal actuator conditions. For example, if an actuator fails (becomes locked) on the main rotor, the cyclic inputs are consequently fixed and the helicopter may become stuck in a flight maneuver. This can obviously be seen as a catastrophic failure, and would likely lead to a crash. These types of failures can be overcome with the application of individual blade control (IBC). IBC is achieved using the blade pitch control method, which provides complete authority of the aerodynamic characteristics of each rotor blade at any given time by replacing the normally rigid pitch links between the swashplate and the pitch horn of the blade with hydraulic or electronic actuators. Thus, IBC can provide the redundancy necessary for subsystem failure accommodation. In this research effort, a simulation environment is developed to investigate the potential of the IBC main rotor configuration for fault-tolerant control. To examine the applications of IBC to failure scenarios and fault-tolerant controls, a conventional, swashplate-based linear model is first developed for hover and forward flight scenarios based on the UH-60 Black Hawk helicopter. The linear modeling techniques for the swashplate-based helicopter are then adapted and expanded to include IBC. Using these modified techniques, an IBC based mathematical model of the UH-60 helicopter is developed for the purposes of simulation and analysis. The methodology can be used to model and implement a different aircraft if geometric, gravimetric, and general aerodynamic data are available. Without the kinetic restrictions of the swashplate, the IBC model effectively decouples the cyclic control inputs between different blades. Simulations of the IBC model prove that the primary control functions can be manually

  18. Operations based optimisation using simulation and CFD

    OpenAIRE

    Doherty, JJ; Clifton, DP; Gillan, MA; Ciampoli, F

    2007-01-01

    An initial investigation of an optimisation based approach for design across a continuous range of operating conditions is presented. The objective for this 'operations based optimisation' approach is to avoid the need to choose critical design point conditions and associated weighting factors by tackling the overall operational performance instead. The approach integrates numerical optimisation, response surface modelling, CFD and operational simulation. An optimisation test bed involving th...

  19. Helium compressor aerodynamic design considerations for MHTGR circulators

    International Nuclear Information System (INIS)

    Compressor aerodynamic design considerations for both the main and shutdown cooling circulators in the Modular High-Temperature Gas-Cooled Reactor (MHTGR) plant are addressed in this paper. A major selection topic relates to the impeller type (i.e., axial or radial flow), and the aerothermal studies leading to the selection of optimum parameters are discussed. For the conceptual designs of the main and shutdown cooling circulators, compressor blading geometries were established and helium gas flow paths defined. Both circulators are conservative by industrial standards in terms of aerodynamic and structural loading, and the blade tip speeds are particularly modest. Performance characteristics are presented, and the designs embody margin to ensure that pressure-rise growth potential can be accomodated should the circuit resistance possibly increase as the plant design advances. The axial flow impeller for the main circulator is very similar to the Fort St. Vrain (FSV) helium compressor which performs well. A significant technology base exists for the MHTGR plant circulators, and this is highlighted in the paper. (author). 15 refs, 16 figs, 12 tabs

  20. An unsteady aerodynamic formulation for efficient rotor tonal noise prediction

    Science.gov (United States)

    Gennaretti, M.; Testa, C.; Bernardini, G.

    2013-12-01

    An aerodynamic/aeroacoustic solution methodology for predction of tonal noise emitted by helicopter rotors and propellers is presented. It is particularly suited for configurations dominated by localized, high-frequency inflow velocity fields as those generated by blade-vortex interactions. The unsteady pressure distributions are determined by the sectional, frequency-domain Küssner-Schwarz formulation, with downwash including the wake inflow velocity predicted by a three-dimensional, unsteady, panel-method formulation suited for the analysis of rotors operating in complex aerodynamic environments. The radiated noise is predicted through solution of the Ffowcs Williams-Hawkings equation. The proposed approach yields a computationally efficient solution procedure that may be particularly useful in preliminary design/multidisciplinary optimization applications. It is validated through comparisons with solutions that apply the airloads directly evaluated by the time-marching, panel-method formulation. The results are provided in terms of blade loads, noise signatures and sound pressure level contours. An estimation of the computational efficiency of the proposed solution process is also presented.

  1. Aerodynamic Optimization of Micro Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Siew Ping Yeong

    2016-01-01

    Full Text Available Computational fluid dynamics (CFD study was done on the propeller design of a micro aerial vehicle (quadrotor-typed to optimize its aerodynamic performance via Shear Stress Transport K-Omega (SST k-ω turbulence model. The quadrotor model used was WL-V303 Seeker. The design process started with airfoils selection and followed by the evaluation of drone model in hovering and cruising conditions. To sustain a 400g payload, by Momentum Theory an ideal thrust of 5.4 N should be generated by each rotor of the quadrotor and this resulted in an induced velocity of 7.4 m/s on the propeller during hovering phase, equivalent to Reynolds number of 10403 at 75% of the propeller blade radius. There were 6 propellers investigated at this Reynolds number. Sokolov airfoil which produced the largest lift-to-drag ratio was selected for full drone installation to be compared with the original model (benchmark. The CFD results showed that the Sokolov propeller generated 0.76 N of thrust more than the benchmark propeller at 7750 rpm. Despite generating higher thrust, higher drag was also experienced by the drone installed with Sokolov propellers. This resulted in lower lift-to-drag ratio than the benchmark propellers. It was also discovered that the aerodynamic performance of the drone could be further improved by changing the rotating direction of each rotor. Without making changes on the structural design, the drone performance increased by 39.58% in terms of lift-to-drag ratio by using this method.

  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. Shape Optimization of Impeller Blades for 15,000 HP Centrifugal Compressor Using Fluid Structural Interaction Analysis

    International Nuclear Information System (INIS)

    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

  4. Effects of flow curvature on the aerodynamics of Darrieus wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Migliore, P. G.; Wolfe, W. P.

    1980-07-01

    A theoretical and experimental investigation was conducted which clearly showed the effects of flow curvature to be significant determinants of Darrieus turbine blade aerodynamics; qualitatively, these results apply equally to straight or curved bladed machines. Unusually large boundary layer radial pressure gradients and virtually altered camber and incidence are the phenomena of primary importance. Conformal mapping techniques were developed which transform the geometric turbine airfoils in curved flow to their virtual equivalents in rectilinear flow, thereby permitting the more accurate selection of airfoil aerodynamic coefficients from published sectional data. It is demonstrated that once the flow idiosyncracies are fully understood, they may be used to advantage to improve the wind energy extraction efficiency of these machines.

  5. 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

  6. Optimised transdermal delivery of pravastatin.

    Science.gov (United States)

    Burger, Cornel; Gerber, Minja; du Preez, Jan L; du Plessis, Jeanetta

    2015-12-30

    Wiechers' programme "Formulating for Efficacy" initiated a new strategy to optimise the oil phase of topical formulations in order to achieve optimal transdermal drug delivery. This new approach uses the "Delivery Gap Theory" on any active pharmaceutical ingredients (APIs) to test if it could enhance transdermal drug delivery. The aim of the study was to formulate six different semi-solid formulations (three creams and three emulgels) with 2% pravastatin as the API in order to investigate the "Delivery Gap Principle", by determining which formulation would deliver pravastatin best to the target-site (system circulation). The three cream- and three emulgel formulations had different polarities, i.e. a formulation with polarity equal to that of the stratum corneum (optimised), a non-polar (lipophilic)- and a polar (hydrophilic)-formulation. Franz cell diffusion studies were executed over 12h and the optimised emulgel (2.578μg/cm(2)) had the highest median amount per area obtained. Tape stripping followed the diffusion studies and in the stratum corneum-epidermis, the hydrophilic emulgel (1.448μg/ml) contained the highest median pravastatin concentration and the epidermis-dermis the optimised emulgel (0.849μg/ml) depicted the highest pravastatin concentration. During this study, it was observed that when both emulgel and cream formulations were compared; the emulgels enhanced the delivery of pravastatin more than the creams. PMID:26505148

  7. Study on Design of High Efficiency and Light Weight Composite Propeller Blade for a Regional Turboprop Aircraft

    Science.gov (United States)

    Kong, Changduk; Lee, Kyungsun

    2013-03-01

    In this study, aerodynamic and structural design of the composite propeller blade for a regional turboprop aircraft is performed. The thin and wide chord propeller blade of high speed turboprop aircraft should have proper strength and stiffness to carry various kinds of loads such as high aerodynamic bending and twisting moments and centrifugal forces. Therefore the skin-spar-foam sandwich structure using high strength and stiffness carbon/epoxy composite materials is used to improve the lightness. A specific design procedure is proposed in this work as follows; firstly the aerodynamic configuration design, which is acceptable for the design requirements, is carried out using the in-house code developed by authors, secondly the structure design loads are determined through the aerodynamic load case analysis, thirdly the spar flange and the skin are preliminarily sized by consideration of major bending moments and shear forces using both the netting rule and the rule of mixture, and finally, the stress analysis is performed to confirm the structural safety and stability using finite element analysis commercial code, MSC. NASTRAN/PATRAN. Furthermore the additional analysis is performed to confirm the structural safety due to bird strike impact on the blade during flight operation using a commercial code, ANSYS. To realize the proposed propeller design, the prototype blades are manufactured by the following procedure; the carbon/epoxy composite fabric prepregs are laid up for skin and spar on a mold using the hand lay-up method and consolidated with a proper temperature and vacuum in the oven. To finalize the structural design, the full-scale static structural test is performed under the simulated aerodynamic loads using 3 point loading method. From the experimental results, it is found that the designed blade has a good structural integrity, and the measured results agree well with the analytical results as well.

  8. Data-driven identification of local structural dynamics in wind turbines under various aerodynamic & marine loads

    OpenAIRE

    Anayurt, Basak

    2015-01-01

    The power generation from wind turbines constitutes an example of highly complex engineering system especially in offshore applications where flow around the tower and nacelle coupled with inflow turbu- lence and rotation of the turbine blades create unpredicted aerodynamic forces which are transmitted into structures like critical joints causing resonance that drastically reduces the design lifetime. Standard approaches that are used in the design to determine stress in structural components...

  9. A Numberical Vortex Approach to Aerodynamic Modeling of SUAV/VTOL Aircraft

    OpenAIRE

    Hunsaker, Douglas; Snyder, Deryl

    2006-01-01

    A numerical lifting line method, coupled with a numerical blade element method, is presented as a low computational cost approach to modeling slipstream effects on a finite wing. This method uses a 3D vortex lifting law along with known 2D airfoil data to predict the lift distribution across a wing in the presence of a propeller slipstream. The results are of significant importance in the development of an aerodynamic modeling package for initial stages of vertical takeoff and landing (VTOL) ...

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

    Directory of Open Access Journals (Sweden)

    Chi-Jeng Bai

    2014-11-01

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

  11. Design of low noise wind turbine blades using Betz and Joukowski concepts

    International Nuclear Information System (INIS)

    This paper presents the aerodynamic design of low noise wind turbine blades using Betz and Joukowski concepts. The aerodynamic model is based on Blade Element Momentum theory whereas the aeroacoustic prediction model is based on the BPM model. The investigation is started with a 3MW baseline/reference turbine rotor with a diameter of 80 m. To reduce the noise emission from the baseline rotor, the rotor is reconstructed with the low noise CQU-DTU-LN1 series of airfoils which has been tested in the acoustic wind tunnel located at Virginia Tech. Finally, 3MW low noise turbine rotors are designed using the concepts of Betz and Joukowski, and the CQU-DTU-LN1 series of airfoils. Performance analysis shows that the newly designed turbine rotors can achieve an overall noise reduction of 6 dB and 1.5 dB(A) with a similar power output as compared to the reference rotor

  12. Introduction to transonic aerodynamics

    CERN Document Server

    Vos, Roelof

    2015-01-01

    Written to teach students the nature of transonic flow and its mathematical foundation, this book offers a much-needed introduction to transonic aerodynamics. The authors present a quantitative and qualitative assessment of subsonic, supersonic, and transonic flow around bodies in two and three dimensions. The book reviews the governing equations and explores their applications and limitations as employed in modeling and computational fluid dynamics.  Some concepts, such as shock and expansion theory, are examined from a numerical perspective. Others, including shock-boundary-layer interaction, are discussed from a qualitative point of view. The book includes 60 examples and more than 200 practice problems. The authors also offer analytical methods such as Method of Characteristics (MOC) that allow readers to practice with the subject matter.  The result is a wealth of insight into transonic flow phenomena and their impact on aircraft design, including compressibility effects, shock and expansion waves, sho...

  13. Wind Turbines Wake Aerodynamics

    DEFF Research Database (Denmark)

    Vermeer, L.; Sørensen, Jens Nørkær; Crespo, A.

    2003-01-01

    The aerodynamics of horizontal axis wind turbine wakes is studied. The contents is directed towards the physics of power extraction by wind turbines and reviews both the near and the far wake region. For the near wake, the survey is restricted to uniform, steady and parallel flow conditions......, thereby excluding wind shear, wind speed and rotor setting changes and yawed conditions. The emphasis is put on measurements in controlled conditions.For the far wake, the survey focusses on both single turbines and wind farm effects, and the experimental and numerical work are reviewed; the main interest...... is to study how the far wake decays downstream, in order to estimate the effect produced in downstream turbines.The article is further restricted to horizontal axis wind turbines and excludes all other types of turbines....

  14. Wind turbine wake aerodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Vermeer, L.J. [Delft University of Technology (Netherlands). Section Wind Energy; Sorensen, J.N. [Technical University of Denmark, Lyngby (Denmark). Dept. of Mechanical Engineering; Crespo, A. [Universidad Politecnica de Madrid (Spain). Dpto. de Ingenieria Energetica y Fluidomecanica

    2003-10-01

    The aerodynamics of horizontal axis wind turbine wakes is studied. The contents is directed towards the physics of power extraction by wind turbines and reviews both the near and the far wake region. For the near wake, the survey is restricted to uniform, steady and parallel flow conditions, thereby excluding wind shear, wind speed and rotor setting changes and yawed conditions. The emphasis is put on measurements in controlled conditions. For the far wake, the survey focuses on both single turbines and wind farm effects, and the experimental and numerical work are reviewed; the main interest is to study how the far wake decays downstream, in order to estimate the effect produced in downstream turbines. The article is further restricted to horizontal axis wind turbines and excludes all other types of turbines. (author)

  15. Cable Aerodynamic Control

    DEFF Research Database (Denmark)

    Kleissl, Kenneth

    categorization of the different control technics together with an identification of two key mechanisms for reduction of the design drag force. During this project extensive experimental work examining the aerodynamics of the currently used cable surface modifications together with new innovative proposals have...... drag force due to the high intensity of streamwise vorticity, whereas the helical fillets resulted in a more gradual flow transition because of the spanwise variation. During yawed flow conditions, the asymmetrical appearance of the helical solution was found to induce a significant lift force with a...... were tested. While a proper discrete helical arrangement of Cylindrical Vortex Generators resulted in a superior drag performance, only systems applying "mini-strakes" were capable of complete rivulet suppression. When the strakes was positioned in a staggered helical arrangement, the innovative system...

  16. Unsteady aerodynamic analysis for offshore floating wind turbines under different wind conditions

    Science.gov (United States)

    Xu, B. F.; Wang, T. G.; Yuan, Y.; Cao, J. F.

    2015-01-01

    A free-vortex wake (FVW) model is developed in this paper to analyse the unsteady aerodynamic performance of offshore floating wind turbines. A time-marching algorithm of third-order accuracy is applied in the FVW model. Owing to the complex floating platform motions, the blade inflow conditions and the positions of initial points of vortex filaments, which are different from the fixed wind turbine, are modified in the implemented model. A three-dimensional rotational effect model and a dynamic stall model are coupled into the FVW model to improve the aerodynamic performance prediction in the unsteady conditions. The effects of floating platform motions in the simulation model are validated by comparison between calculation and experiment for a small-scale rigid test wind turbine coupled with a floating tension leg platform (TLP). The dynamic inflow effect carried by the FVW method itself is confirmed and the results agree well with the experimental data of a pitching transient on another test turbine. Also, the flapping moment at the blade root in yaw on the same test turbine is calculated and compares well with the experimental data. Then, the aerodynamic performance is simulated in a yawed condition of steady wind and in an unyawed condition of turbulent wind, respectively, for a large-scale wind turbine coupled with the floating TLP motions, demonstrating obvious differences in rotor performance and blade loading from the fixed wind turbine. The non-dimensional magnitudes of loading changes due to the floating platform motions decrease from the blade root to the blade tip. PMID:25583859

  17. Structural effects of unsteady aerodynamic forces on horizontal-axis wind turbines

    Science.gov (United States)

    Miller, M. S.; Shipley, D. E.

    1994-08-01

    Due to its renewable nature and abundant resources, wind energy has the potential to fulfill a large portion of this nation's energy needs. The simplest means of utilizing wind energy is through the use of downwind, horizontal-axis wind turbines (HAWT) with fixed-pitch rotors. This configuration regulates the peak power by allowing the rotor blade to aerodynamically stall. The stall point, the point of maximum coefficient of lift, is currently predicted using data obtained from wind tunnel tests. Unfortunately, these tests do not accurately simulate conditions encountered in the field. Flow around the tower and nacelle coupled with inflow turbulence and rotation of the turbine blades create unpredicted aerodynamic forces. Dynamic stall is hypothesized to occur. Such aerodynamic loads are transmitted into the rotor and tower causing structural resonance that drastically reduces the design lifetime of the wind turbine. The current method of alleviating this problem is to structurally reinforce the tower and blades. However, this adds unneeded mass and, therefore, cost to the turbines. A better understanding of the aerodynamic forces and the manner in which they affect the structure would allow for the design of more cost effective and durable wind turbines. Data compiled by the National Renewable Energy Laboratory (NREL) for a downwind HAWT with constant chord, untwisted, fixed-pitch rotors is analyzed. From these data, the actual aerodynamic characteristics of the rotor are being portrayed and the potential effects upon the structure can for the first time be fully analyzed. Based upon their understanding, solutions to the problem of structural resonance are emerging.

  18. Validation of DYSTOOL for unsteady aerodynamic modeling of 2D airfoils

    International Nuclear Information System (INIS)

    From the point of view of wind turbine modeling, an important group of tools is based on blade element momentum (BEM) theory using 2D aerodynamic calculations on the blade elements. Due to the importance of this sectional computation of the blades, the National Renewable Wind Energy Center of Spain (CENER) developed DYSTOOL, an aerodynamic code for 2D airfoil modeling based on the Beddoes-Leishman model. The main focus here is related to the model parameters, whose values depend on the airfoil or the operating conditions. In this work, the values of the parameters are adjusted using available experimental or CFD data. The present document is mainly related to the validation of the results of DYSTOOL for 2D airfoils. The results of the computations have been compared with unsteady experimental data of the S809 and NACA0015 profiles. Some of the cases have also been modeled using the CFD code WMB (Wind Multi Block), within the framework of a collaboration with ACCIONA Windpower. The validation has been performed using pitch oscillations with different reduced frequencies, Reynolds numbers, amplitudes and mean angles of attack. The results have shown a good agreement using the methodology of adjustment for the value of the parameters. DYSTOOL have demonstrated to be a promising tool for 2D airfoil unsteady aerodynamic modeling

  19. Validation of DYSTOOL for unsteady aerodynamic modeling of 2D airfoils

    Science.gov (United States)

    González, A.; Gomez-Iradi, S.; Munduate, X.

    2014-06-01

    From the point of view of wind turbine modeling, an important group of tools is based on blade element momentum (BEM) theory using 2D aerodynamic calculations on the blade elements. Due to the importance of this sectional computation of the blades, the National Renewable Wind Energy Center of Spain (CENER) developed DYSTOOL, an aerodynamic code for 2D airfoil modeling based on the Beddoes-Leishman model. The main focus here is related to the model parameters, whose values depend on the airfoil or the operating conditions. In this work, the values of the parameters are adjusted using available experimental or CFD data. The present document is mainly related to the validation of the results of DYSTOOL for 2D airfoils. The results of the computations have been compared with unsteady experimental data of the S809 and NACA0015 profiles. Some of the cases have also been modeled using the CFD code WMB (Wind Multi Block), within the framework of a collaboration with ACCIONA Windpower. The validation has been performed using pitch oscillations with different reduced frequencies, Reynolds numbers, amplitudes and mean angles of attack. The results have shown a good agreement using the methodology of adjustment for the value of the parameters. DYSTOOL have demonstrated to be a promising tool for 2D airfoil unsteady aerodynamic modeling.

  20. SERI advanced wind turbine blades

    Science.gov (United States)

    Tangler, J.; Smith, B.; Jager, D.

    1992-02-01

    The primary goal of the Solar Energy Research Institute's (SERI) advanced wind turbine blades is to convert the kinetic energy in the wind into mechanical energy in an inexpensive and efficient manner. To accomplish this goal, advanced wind turbine blades have been developed by SERI that utilize unique airfoil technology. Performance characteristics of the advanced blades were verified through atmospheric testing on fixed-pitch, stall-regulated horizontal-axis wind turbines (HAWTs). Of the various wind turbine configurations, the stall-regulated HAWT dominates the market because of its simplicity and low cost. Results of the atmospheric tests show that the SERI advanced blades produce 10 percent to 30 percent more energy than conventional blades.

  1. Design of centrifugal impeller blades

    Science.gov (United States)

    Betz, A; Flugge-Lotz, I

    1939-01-01

    This paper restricts itself to radial impellers with cylindrical blades since, as Prasil has shown, the flow about an arbitrarily curved surface of revolution may be reduced to this normal form we have chosen by a relatively simple conformal transformation. This method starts from the simple hypotheses of the older centrifugal impeller theory by first assuming an impeller with an infinite number of blades. How the flow is then modified is then investigated. For the computation of flow for a finite number of blades, the approximation method as developed by Munk, Prandtl and Birnbaum, or Glauert is found suitable. The essential idea of this method is to replace the wing by a vortex sheet and compute the flow as the field of these vortices. The shape of the blades is then obtained from the condition that the flow must be along the surface of the blade.

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

    Science.gov (United States)

    Skrzypiński, Witold; Gaunaa, Mac; Bak, Christian

    2014-06-01

    The aim of the current work is to analyze possible advantages of mounting Vortex Generators (VG's) on a wind turbine blade. Specifically, the project aims at investigating at which radial sections of the DTU 10 MW Reference Wind Turbine blade it is most beneficial to mount the VG's in order to increase the Annual Energy Production (AEP) under realistic conditions. The present analysis was carried out in several steps: (1) The clean two dimensional airfoil characteristics were first modified to emulate the effect of all possible combinations of VG's (1% high at suction side x/c=0.2-0.25) and two Leading Edge Roughness (LER) values along the whole blade span. (2) The combinations from Step 1, including the clean case were subsequently modified to take into account three dimensional effects. (3) BEM computations were carried out to determine the aerodynamic rotor performance using each of the datasets from Step 2 along the whole blade span for all wind speeds in the turbine control scheme. (4) Employing the assumption of radial independence between sections of the blades, and using the results of the BEM computations described in Step 3, it is possible to determine for each radial position independently whether it is beneficial to install VG's in the smooth and LER cases, respectively. The results indicated that surface roughness that corresponds to degradation of the power curve may to some extent be mitigated by installation of VG's. The present results also indicated that the optimal VG configuration in terms of maximizing AEP depends on the degree of severity of the LER. This is because, depending on the condition of blade surface, installation of VG's on an incorrect blade span or installation of VG's too far out on the blade may cause loss in AEP. The results also indicated that the worse condition of the blade surface, the more gain may be obtained from the installation of VG's.

  3. Application of Out-of-Plane Warping to Control Rotor Blade Twist

    Science.gov (United States)

    VanWeddingen, Yannick; Bauchau, Olivier; Kottapalli, Sesi; Ozbay, Serkan; Mehrotra, Yogesh

    2012-01-01

    The goal of this ongoing study is to develop and demonstrate the feasibility of a blade actuation system to dynamically change the twist, and/or the camber, of an airfoil section and, consequently, alter the in-flight aerodynamic loading on the blade for efficient flight control. The required analytical and finite element tools are under development to enable an accurate and comprehensive aeroelastic assessment of the current Full-Blade Warping and 3D Warping Actuated Trailing Edge Flap concepts. The feasibility of the current concepts for swashplateless rotors and higher harmonic blade control is also being investigated. In particular, the aim is to complete the following objectives, some of which have been completed (as noted below) and others that are currently ongoing: i) Develop a Vlasov finite element model and validate against the ABAQUS shell models (completed). ii) Implement the 3D warping actuation concept within the comprehensive analysis code DYMORE. iii) Perform preliminary aeroelastic simulations of blades using DYMORE with 3D warping actuation: a) Investigate the blade behavior under 1 per/rev actuation. Determine whether sufficient twist can be generated and sustained to achieve primary blade control. b) Investigate the behavior of a trailing edge flap configuration under higher harmonic excitations. Determine how much twist can be obtained at the harmonics 2-5 per/rev. iv) Determine actuator specifications such as the power required, load and displacements, and identify the stress and strain distributions in the actuated blades. In general, the completion of Item ii) above will give an additional research capability in rotorcraft dynamics analyses, i.e., the capability to calculate the rotor blade twist due to warping, something that is not currently available in any of the existing comprehensive rotorcraft analyses.

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

    International Nuclear Information System (INIS)

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

  5. On Measurement and Evaluation of Flow Conditions at Limit Loadof Turbine Blade Cascades

    Czech Academy of Sciences Publication Activity Database

    Šafařík, P.; Luxa, Martin; Picmausová, Helena; Šimurda, David

    Valencia : Universitat Politechnica de Valencia, 2013 - (Desantes, J.; Paniagua, G.; Serrano, J.), s. 109-114 ISBN 978-84-8363-966-5. [Biannual Symposium on Measuring Techniques in Turbomachinery /11./. Valencia (ES), 22.03.2012-23.03.2012] R&D Projects: GA AV ČR(CZ) IAA200760801 Institutional research plan: CEZ:AV0Z20760514 Keywords : limit load * turbine blade cascades * experimental aerodynamics Subject RIV: BK - Fluid Dynamics

  6. Effects of inlet circumferential fluctuation on the sweep aerodynamic performance of axial fans/compressors

    Science.gov (United States)

    Gui, Xingmin; Zhu, Fang; Wan, Ke; Jin, Donghai

    2013-10-01

    Swept blades have been widely used in the transonic fan/compressor of aircraft engines with the aids of 3D CFD simulation since the design concept of controlling the shock structure was firstly proposed and successfully tested by Dr. Wennerstrom in the 1980s. However, some disadvantage phenomenon has also been induced by excessively 3D blade geometries on the structure stress insufficiency, vibration and reliability. Much confusion in the procedure of design practice leading us to recognize a new view on the flow mechanism of sweep aerodynamical induction: the new radial equilibrium established by the influence of inlet circumferential fluctuation (CF) changes the inlet flows of blading and induces the performance modification of axial fans/compressors blade. The view is verified by simplified models through numerical simulation and circumferentially averaged analysis in the present paper. The results show that the CF source items which originate from design parameters, such as the spanwise distributions of the loading and blading geometries, contribute to the changing of averaged incidence spanwise distribution, and further more affect the performance of axial fans/compressors with swept blades.

  7. Unsteady Aerodynamics Experiment Phase V: Test Configuration and Available Data Campaigns; TOPICAL

    International Nuclear Information System (INIS)

    The main objective of the Unsteady Aerodynamics Experiment is to provide information needed to quantify the full-scale, three-dimensional, unsteady aerodynamic behavior of horizontal-axis wind turbines (HAWTs). To accomplish this, an experimental wind turbine configured to meet specific research objectives was assembled and operated at the National Renewable Energy Laboratory (NREL). The turbine was instrumented to characterize rotating-blade aerodynamic performance, machine structural responses, and atmospheric inflow conditions. Comprehensive tests were conducted with the turbine operating in an outdoor field environment under diverse conditions. Resulting data are used to validate aerodynamic and structural dynamics models, which are an important part of wind turbine design and engineering codes. Improvements in these models are needed to better characterize aerodynamic response in both the steady-state post-stall and dynamic-stall regimes. Much of the effort in the first phase of the Unsteady Aerodynamics Experiment focused on developing required data acquisition systems. Complex instrumentation and equipment was needed to meet stringent data requirements while operating under the harsh environmental conditions of a wind turbine rotor. Once the data systems were developed, subsequent phases of experiments were then conducted to collect data for use in answering specific research questions. A description of the experiment configuration used during Phase V of the experiment is contained in this report

  8. IEA joint action. Aerodynamics of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Maribo Pedersen, B. [ed.

    1997-08-01

    The advances to be made in aerodynamic prediction requires a deeper understanding of the physical processes occurring at the blades, and in the wake, of a wind turbine. This can only come from a continuing process of experimental observation and theoretical analysis. The present symposium presents the opportunity to do this by exchange of data from experiments and simulations, and by discussion of new or modified wake theories. The symposium will consists of a number of presentations by invited speakers and conclude with a summary of the talks and a round-the-table technical discussion. The talks offer the change to present behaviour from full-scale and laboratory experiments that are not explained by existing prediction codes. In addition, presentations are welcome on new modelling techniques or formulations that could make existing codes more accurate, less computationally intensive and easier to use. This symposium is intended to provide a starting point for the formulation of advanced rotor performance methods, which will improve the accuracy of load and performance prediction codes useful to the wind turbine industry. (au)

  9. NWTC Aerodynamics Studies Improve Energy Capture and Lower Costs of Wind-Generated Electricity

    Energy Technology Data Exchange (ETDEWEB)

    2015-08-01

    Researchers at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) have expanded wind turbine aerodynamic research from blade and rotor aerodynamics to wind plant and atmospheric inflow effects. The energy capture from wind plants is dependent on all of these aerodynamic interactions. Research at the NWTC is crucial to understanding how wind turbines function in large, multiple-row wind plants. These conditions impact the cumulative fatigue damage of turbine structural components that ultimately effect the useful lifetime of wind turbines. This work also is essential for understanding and maximizing turbine and wind plant energy production. Both turbine lifetime and wind plant energy production are key determinants of the cost of wind-generated electricity.

  10. Numerical Investigation of Aerodynamic Performance and Loads of a Novel Dual Rotor Wind Turbine

    Directory of Open Access Journals (Sweden)

    Behnam Moghadassian

    2016-07-01

    Full Text Available The objective of this paper is to numerically investigate the effects of the atmospheric boundary layer on the aerodynamic performance and loads of a novel dual-rotor wind turbine (DRWT. Large eddy simulations are carried out with the turbines operating in the atmospheric boundary layer (ABL and in a uniform inflow. Two stability conditions corresponding to neutral and slightly stable atmospheres are investigated. The turbines are modeled using the actuator line method where the rotor blades are modeled as body forces. Comparisons are drawn between the DRWT and a comparable conventional single-rotor wind turbine (SRWT to assess changes in aerodynamic efficiency and loads, as well as wake mixing and momentum and kinetic energy entrainment into the turbine wake layer. The results show that the DRWT improves isolated turbine aerodynamic performance by about 5%–6%. The DRWT also enhances turbulent axial momentum entrainment by about 3.3 %. The highest entrainment is observed in the neutral stability case when the turbulence in the ABL is moderately high. Aerodynamic loads for the DRWT, measured as out-of-plane blade root bending moment, are marginally reduced. Spectral analyses of ABL cases show peaks in unsteady loads at the rotor passing frequency and its harmonics for both rotors of the DRWT.

  11. Evaluation of Aeroelastically Tailored Small Wind Turbine Blades Final Project Report

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Dayton A.

    2005-09-29

    Evaluation of Aeroelastically Tailored Small Wind Turbine Blades Final Report Global Energy Concepts, LLC (GEC) has performed a conceptual design study concerning aeroelastic tailoring of small wind turbine blades. The primary objectives were to evaluate ways that blade/rotor geometry could be used to enable cost-of-energy reductions by enhancing energy capture while constraining or mitigating blade costs, system loads, and related component costs. This work builds on insights developed in ongoing adaptive-blade programs but with a focus on application to small turbine systems with isotropic blade material properties and with combined blade sweep and pre-bending/pre-curving to achieve the desired twist coupling. Specific goals of this project are to: (A) Evaluate and quantify the extent to which rotor geometry can be used to realize load-mitigating small wind turbine rotors. Primary aspects of the load mitigation are: (1) Improved overspeed safety affected by blades twisting toward stall in response to speed increases. (2) Reduced fatigue loading affected by blade twisting toward feather in response to turbulent gusts. (B) Illustrate trade-offs and design sensitivities for this concept. (C) Provide the technical basis for small wind turbine manufacturers to evaluate this concept and commercialize if the technology appears favorable. The SolidWorks code was used to rapidly develop solid models of blade with varying shapes and material properties. Finite element analyses (FEA) were performed using the COSMOS code modeling with tip-loads and centripetal accelerations. This tool set was used to investigate the potential for aeroelastic tailoring with combined planform sweep and pre-curve. An extensive matrix of design variables was investigated, including aerodynamic design, magnitude and shape of planform sweep, magnitude and shape of blade pre-curve, material stiffness, and rotor diameter. The FEA simulations resulted in substantial insights into the structural

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

    Directory of Open Access Journals (Sweden)

    RAMZI MDOUKI

    2013-10-01

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

  13. Isogeometric Analysis and Shape Optimisation

    DEFF Research Database (Denmark)

    Gravesen, Jens; Evgrafov, Anton; Gersborg, Allan Roulund;

    One of the attractive features of isogeometric analysis is the exact representation of the geometry. The geometry is furthermore given by a relative low number of control points and this makes isogeometric analysis an ideal basis for shape optimisation. I will describe some of the results we have...... obtained and also some of the problems we have encountered. One of these problems is that the geometry of the shape is given by the boundary alone. And, it is the parametrisation of the boundary which is changed by the optimisation procedure. But isogeometric analysis requires a parametrisation of the...... will explain how the validity of a parametrisation can be checked and we will describe various ways to parametrise a domain. We will in particular study the Winslow functional which turns out to have some desirable properties. Other problems we touch upon is clustering of boundary control points...

  14. Constrained optimisation of spatial sampling

    OpenAIRE

    Groenigen, van, M.

    1999-01-01

    AimsThis thesis aims at the development of optimal sampling strategies for geostatistical studies. Special emphasis is on the optimal use of ancillary data, such as co-related imagery, preliminary observations and historic knowledge. Although the object of all studies is the soil, the developed methodology can be used in any scientific field dealing with geostatistics.In summary, the objectives of this study were:Formulation of a range of optimisation criteria that honour a wide variety of ai...

  15. Optimising Comprehensibility in Interlingual Translation

    DEFF Research Database (Denmark)

    Nisbeth Jensen, Matilde

    2015-01-01

    . It is argued that Plain Language writing is a type of intralingual translation as it involves rewriting or translating a complex monolingual text into comprehensible language. Based on Plain Language literature, a comprehensibility framework is elaborated, which is subsequently exemplified through...... the functional text type of Patient Information Leaflet. Finally, the usefulness of applying the principles of Plain Language and intralingual translation for optimising comprehensibility in interlingual translation is discussed....

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

    Institute of Scientific and Technical Information of China (English)

    Zhang Shaowen; David G. MacManus; Luo Jianqiao

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Zhang Shaowen

    2016-02-01

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

  18. Naval Aerodynamics Test Facility (NATF)

    Data.gov (United States)

    Federal Laboratory Consortium — The NATF specializes in Aerodynamics testing of scaled and fullsized Naval models, research into flow physics found on US Navy planes and ships, aerosol testing and...

  19. Computational aerodynamics and artificial intelligence

    Science.gov (United States)

    Mehta, U. B.; Kutler, P.

    1984-01-01

    The general principles of artificial intelligence are reviewed and speculations are made concerning how knowledge based systems can accelerate the process of acquiring new knowledge in aerodynamics, how computational fluid dynamics may use expert systems, and how expert systems may speed the design and development process. In addition, the anatomy of an idealized expert system called AERODYNAMICIST is discussed. Resource requirements for using artificial intelligence in computational fluid dynamics and aerodynamics are examined. Three main conclusions are presented. First, there are two related aspects of computational aerodynamics: reasoning and calculating. Second, a substantial portion of reasoning can be achieved with artificial intelligence. It offers the opportunity of using computers as reasoning machines to set the stage for efficient calculating. Third, expert systems are likely to be new assets of institutions involved in aeronautics for various tasks of computational aerodynamics.

  20. Classical Flutter and Active Control of Wind Turbine Blade Based on Piezoelectric Actuation

    Directory of Open Access Journals (Sweden)

    Tingrui Liu

    2015-01-01

    Full Text Available The aim of this article is to analyze classical flutter and active control of single-cell thin-walled composite wind turbine blade beam based on piezoelectric actuation. Effects of piezoelectric actuation for classical flutter suppression on wind turbine blade beam subjected to combined transverse shear deformation, warping restraint effect, and secondary warping are investigated. The extended Hamilton’s principle is used to set up the equations of motion, and the Galerkin method is applied to reduce the aeroelastic coupled equations into a state-space form. Active control is developed to enhance the vibrational behavior and dynamic response to classical aerodynamic excitation and stabilize structures that might be damaged in the absence of control. Active optimal control scheme based on linear quadratic Gaussian (LQG controller is implemented. The research provides a way for rare study of classical flutter suppression and active control of wind turbine blade based on piezoelectric actuation.

  1. Shaft flexibility effects on the forced response of a bladed-disk assembly

    Science.gov (United States)

    Khader, N.; Loewy, R. G.

    1990-01-01

    A model analysis approach is used to study the forced response of an actual flexible bladed-disk-shaft system. Both in-plane and out-of-plane flexible deformations of the bladed-disk assembly are considered, in addition to its rigid-body translations and rotations, resulting from the bending of the supporting flexible shaft in two orthogonal planes. The effects of Coriolis forces and structural coupling between flexible and rigid disk motions on the system's response are investigated. Aerodynamic loads acting on the rotating and vibrating bladed-disk assembly are accounted for through a simple quasi-steady representation, to evaluate their influence, combined with shaft flexibility and Coriolis effects.

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

    Science.gov (United States)

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

    1985-01-01

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

  3. Failure analysis of turbine blades

    International Nuclear Information System (INIS)

    Two 20 MW gas turbines suffered damage in blades belonging to the 2nd. stage of the turbine after 24,000 hours of duty. From research it arises that the fuel used is not quite adequate to guarantee the blade's operating life due to the excess of SO3, C and Na existing in combustion gases which cause pitting to the former. Later, the corrosion phenomenon is presented under tension produced by working stress enhanced by pitting where Pb is its main agent. A change of fuel is recommended thus considering the blades will reach the operational life they were designed for. (Author)

  4. Aerodynamics of badminton shuttlecocks

    Science.gov (United States)

    Verma, Aekaansh; Desai, Ajinkya; Mittal, Sanjay

    2013-08-01

    A computational study is carried out to understand the aerodynamics of shuttlecocks used in the sport of badminton. The speed of the shuttlecock considered is in the range of 25-50 m/s. The relative contribution of various parts of the shuttlecock to the overall drag is studied. It is found that the feathers, and the net in the case of a synthetic shuttlecock, contribute the maximum. The gaps, in the lower section of the skirt, play a major role in entraining the surrounding fluid and causing a difference between the pressure inside and outside the skirt. This pressure difference leads to drag. This is confirmed via computations for a shuttlecock with no gaps. The synthetic shuttle experiences more drag than the feather model. Unlike the synthetic model, the feather shuttlecock is associated with a swirling flow towards the end of the skirt. The effect of the twist angle of the feathers on the drag as well as the flow has also been studied.

  5. Aerodynamics of bird flight

    Directory of Open Access Journals (Sweden)

    Dvořák Rudolf

    2016-01-01

    Full Text Available Unlike airplanes birds must have either flapping or oscillating wings (the hummingbird. Only such wings can produce both lift and thrust – two sine qua non attributes of flying.The bird wings have several possibilities how to obtain the same functions as airplane wings. All are realized by the system of flight feathers. Birds have also the capabilities of adjusting the shape of the wing according to what the immediate flight situation demands, as well as of responding almost immediately to conditions the flow environment dictates, such as wind gusts, object avoidance, target tracking, etc. In bird aerodynamics also the tail plays an important role. To fly, wings impart downward momentum to the surrounding air and obtain lift by reaction. How this is achieved under various flight situations (cruise flight, hovering, landing, etc., and what the role is of the wing-generated vortices in producing lift and thrust is discussed.The issue of studying bird flight experimentally from in vivo or in vitro experiments is also briefly discussed.

  6. Aerodynamics of bird flight

    Science.gov (United States)

    Dvořák, Rudolf

    2016-03-01

    Unlike airplanes birds must have either flapping or oscillating wings (the hummingbird). Only such wings can produce both lift and thrust - two sine qua non attributes of flying.The bird wings have several possibilities how to obtain the same functions as airplane wings. All are realized by the system of flight feathers. Birds have also the capabilities of adjusting the shape of the wing according to what the immediate flight situation demands, as well as of responding almost immediately to conditions the flow environment dictates, such as wind gusts, object avoidance, target tracking, etc. In bird aerodynamics also the tail plays an important role. To fly, wings impart downward momentum to the surrounding air and obtain lift by reaction. How this is achieved under various flight situations (cruise flight, hovering, landing, etc.), and what the role is of the wing-generated vortices in producing lift and thrust is discussed.The issue of studying bird flight experimentally from in vivo or in vitro experiments is also briefly discussed.

  7. Rotating vibration behavior of the turbine blades with different groups of blades

    Science.gov (United States)

    Tsai, Gwo-Chung

    2004-04-01

    The rotating vibration behaviors of full cycle of 60 blades are studied in this report. The dynamic analysis of two different structures in one of which there are 10 groups of 6 blades and in the other 5 groups of 12 blades, is performed to investigate behavior deviation. In this research, the following jobs are considered: (1) collect the geometric dimensions and material properties of a single blade, (2) create the finite element model of a single blade, a group of 6 blades and 12 blades, and full cycle of 60 blades, (3) perform the vibration analyses of a single blade, a group of blades and a full circle of 60 blades, (4) perform the steady state stress analysis of the blade with different rotating speed; (5) get the Campbell diagram for the full circle of blades, and (6) make comparisons between a group of 6 blades and a group of 12 blades. The conclusions from the analyses are the following: (1) the contact elements are applied to groups of 6 and 12 blades systems and the highest stresses are observed at the location of the first neck of the blade root. These results completely agree very well with in-site observations. (2) The big differences were present in the Campbell diagram: resonant frequencies are observed in the first vibration group for the full system comprising the group of 6 blades and resonant frequencies are not found in the first vibration group of the full blade system made of the group of 12 blades. (3) The dynamic behavior of the full blade system comprised of a group of 6 blades was found much different from that of the full blade system made is of a group of 12 blades. (4) Excellent agreements for the vibration frequencies and mode shapes of a single blade and a full circle of blades are obtained between the FEA results and experimental data.

  8. Flow separation on wind turbines blades

    Science.gov (United States)

    Corten, G. P.

    2001-01-01

    the angle of attack. The art of designing stall rotors is to make the separated area on the blades extend in such a way, that the extracted power remains precisely constant, independent of the wind speed, while the power in the wind at cut-out exceeds the maximum power of the turbine by a factor of 8. Since the stall behaviour is influenced by many parameters, this demand cannot be easily met. However, if it can be met, the advantage of stall control is its passive operation, which is reliable and cheap. Problem Definition In practical application, stall control is not very accurate and many stall-controlled turbines do not meet their specifications. Deviations of the design-power in the order of tens of percent are regular. In the nineties, the aerodynamic research on these deviations focussed on: profile aerodynamics, computational fluid dynamics, rotational effects on separation and pressure measurements on test turbines. However, this did not adequately solve the actual problems with stall turbines. In this thesis, we therefore formulated the following as the essential question: "Does the separated blade area really extend with the wind speed, as we predict?" To find the answer a measurement technique was required, which 1) was applicable on large commercial wind turbines, 2) could follow the dynamic changes of the stall pattern, 3) was not influenced by the centrifugal force and 4) did not disturb the flow. Such a technique was not available, therefore we decided to develop it. Stall Flag Method For this method, a few hundred indicators are fixed to the rotor blades in a special pattern. These indicators, called "stall flags" are patented by the Netherlands Energy Research Foundation (ECN). They have a retro-reflective area which, depending on the flow direction, is or is not covered. A powerful light source in the field up to 500m behind the turbine illuminates the swept rotor area. The uncovered reflectors reflect the light to the source, where a digital video

  9. Aerodynamic flow simulation of wind turbine: Downwind versus upwind configuration

    Energy Technology Data Exchange (ETDEWEB)

    Janajreh, Isam; Qudaih, Rana; Talab, Ilham [Masdar Institute of Science and Technology (MIST), Mechanical Engineering, P.O. Box 54224, Abu Dhabi (United Arab Emirates); Ghenai, Chaouki [Florida Atlantic University, Mechanical Engineering Department, 777 Glades Road, 36-223, Boca Raton, FL 44341 (United States)

    2010-08-15

    Large scale wind turbines and wind farms continue to grow mounting 94.1 GW of the electrical grid capacity in 2007 and expected to reach 160.0 GW in 2010. Wind energy plays a vital role in the quest for renewable and sustainable energy as well as in reducing carbon emission. Early generation wind turbines (windmills) were used mainly for water pumping and seed grinding, whereas today they generate 1/5 of the current Denmark's electricity and will double its grid capacity reaching 12.5% in 2010. Wind energy is plentiful (72 TW estimated to be commercially viable) and clean while its intensive capital cost still impede widespread deployment. However, there are technological challenges, i.e. high fatigue load, noise emission, and meeting stringent reliability and safety standards. Newer inventions, e.g., downstream wind turbines and flapping rotor blades, are sought to enhance their performance, i.e. lower turning moments and cut-in speed and to absorb portion of the cost due to the absent of yaw mechanisms. In this work, numerical analysis of the downstream wind turbine blade is conducted. In particular, the interaction between the tower and the rotor passage is investigated. Circular cross sectional tower and aerofoil shapes are considered in a staggered configuration and under cross-stream motion. The resulting blade static pressure and aerodynamic forces are computed at different incident wind angles and wind speeds. The computed forces are compared to the conventional upstream wind turbine. Steady state and transient, incompressible, viscous Navier-Stokes and turbulent flow analysis are employed. The k-epsilon model is utilized as the turbulence closure. The passage of the rotor blade is governed by ALE and is represented numerically as a sliding mesh against the upstream fixed tower domain. (author)

  10. Robust optimisation of railway crossing geometry

    Science.gov (United States)

    Wan, Chang; Markine, Valeri; Dollevoet, Rolf

    2016-05-01

    This paper presents a methodology for improving the crossing (frog) geometry through the robust optimisation approach, wherein the variability of the design parameters within a prescribed tolerance is included in the optimisation problem. Here, the crossing geometry is defined by parameterising the B-spline represented cross-sectional shape and the longitudinal height profile of the nose rail. The dynamic performance of the crossing is evaluated considering the variation of wheel profiles and track alignment. A multipoint approximation method (MAM) is applied in solving the optimisation problem of minimising the contact pressure during the wheel-rail contact and constraining the location of wheel transition at the crossing. To clarify the difference between the robust optimisation and the normal deterministic optimisation approaches, the optimisation problems are solved in both approaches. The results show that the deterministic optimum fails under slight change of the design variables; the robust optimum, however, has improved and robust performance.

  11. Spline for blade grids design

    Science.gov (United States)

    Korshunov, Andrei; Shershnev, Vladimir; Korshunova, Ksenia

    2015-08-01

    Methods of designing blades grids of power machines, such as equal thickness shape built on middle-line arc, or methods based on target stress spreading were invented long time ago, well described and still in use. Science and technology has moved far from that time and laboriousness of experimental research, which were involving unique equipment, requires development of new robust and flexible methods of design, which will determine the optimal geometry of flow passage.This investigation provides simple and universal method of designing blades, which, in comparison to the currently used methods, requires significantly less input data but still provides accurate results. The described method is purely analytical for both concave and convex sides of the blade, and therefore lets to describe the curve behavior down the flow path at any point. Compared with the blade grid designs currently used in industry, geometric parameters of the designs constructed with this method show the maximum deviation below 0.4%.

  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. Recent Filesystem Optimisations in FreeBSD

    OpenAIRE

    Dowse, Ian; Malone, David

    2002-01-01

    In this paper we summarise four recent optimisations to the FFS implementation in FreeBSD: soft updates, dirpref, vmiodir and dirhash. We then give a detailed exposition of dirhash’s implementation. Finally we study these optimisations under a variety of benchmarks and look at their interactions. Under micro-benchmarks, combinations of these optimisations can offer improvements of over two orders of magnitude. Even real-world workloads see improvements by a factor of 2–10.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-22

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

  15. Blade tip timing (BTT) uncertainties

    Science.gov (United States)

    Russhard, Pete

    2016-06-01

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

  16. Discrete vortex method simulations of aerodynamic admittance in bridge aerodynamics

    DEFF Research Database (Denmark)

    Rasmussen, Johannes Tophøj; Hejlesen, Mads Mølholm; Larsen, Allan; Walther, Jens Honore

    The meshless and remeshed Discrete Vortex Method (DVM) has been widely used in academia and by the industry to model two-dimensional flow around bluff bodies. The implementation “DVMFLOW” [1] is used by the bridge design company COWI to determine and visualise the flow field around bridge sections......, and to determine aerodynamic forces and the corresponding flutter limit. A simulation of the three-dimensional bridge responseto turbulent wind is carried out by quasi steady theory by modelling the bridge girder as a line like structure [2], applying the aerodynamic load coefficients found from the...... current version of DVMFLOW in a strip wise fashion. Neglecting the aerodynamic admittance, i.e. the correlation of the instantaneous lift force to the turbulent fluctuations in the vertical velocities, leads to higher response to high frequency atmospheric turbulence than would be obtained from wind tunnel...

  17. Design of low noise airfoil with high aerodynamic performance for use on small wind turbines

    Institute of Scientific and Technical Information of China (English)

    Taehyung; KIM; Seungmin; LEE; Hogeon; KIM; Soogab; LEE

    2010-01-01

    Wind power is one of the most reliable renewable energy sources and internationally installed capacity is increasing radically every year.Although wind power has been favored by the public in general,the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased.Low noise wind turbine design is becoming more and more important as noise is spreading more adverse effect of wind turbine to public.This paper demonstrates the design of 10 kW class wind turbines,each of three blades,a rotor diameter 6.4 m,a rated rotating speed 200 r/min and a rated wind speed 10 m/s.The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade is trailing edge noise from the outer 25% of the blade.Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at 1.02×106 with a lift performance,which is resistant to surface contamination and turbulence intensity.The objectives in the design process are to reduce noise emission,while sustaining high aerodynamic efficiency.Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al.and Lowson associated with typical wind turbine operation conditions.During the airfoil redesign process,the aerodynamic performance is analyzed to reduce the wind turbine power loss.The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis.Therefore,the new optimized airfoil showing 2.9 dB reductions of total sound pressure level(SPL) and higher aerodynamic performance are achieved.

  18. Research on Flow Characteristics of Supercritical CO2 Axial Compressor Blades by CFD Analysis

    Science.gov (United States)

    Takagi, Kazuhisa; Muto, Yasushi; Ishizuka, Takao; Kikura, Hiroshige; Aritomi, Masanori

    A supercritical CO2 gas turbine of 20MPa is suitable to couple with the Na-cooled fast reactor since Na - CO2 reaction is mild at the outlet temperature of 800K, the cycle thermal efficiency is relatively high and the size of CO2 gas turbine is very compact. In this gas turbine cycle, a compressor operates near the critical point. The property of CO2 and then the behavior of compressible flow near the critical point changes very sharply. So far, such a behavior is not examined sufficiently. Then, it is important to clarify compressible flow near the critical point. In this paper, an aerodynamic design of the axial supercritical CO2 compressor for this system has been carried out based on the existing aerodynamic design method of Cohen1). The cycle design point was selected to achieve the maximum cycle thermal efficiency of 43.8%. For this point, the compressor design conditions were determined. They are a mass flow rate of 2035kg/s, an inlet temperature of 308K, an inlet static pressure of 8.26MPa, an outlet static pressure of 20.6MPa and a rotational speed of 3600rpm. The mean radius was constant through axial direction. The design point was determined so as to keep the diffusion factor and blade stress within the allowable limits. Number of stages and an expected adiabatic efficiency was 14 and 87%, respectively. CFD analyses by FLUENT have been done for this compressor blade. The blade model consists of one set of a guide vane, a rotor blade and a stator blade. The analyses were conducted under the assumption both of the real gas properties and also of the modified ideal gas properties. Using the real gas properties, analysis was conducted for the 14th blade, whose condition is remote from the critical point and the possibility of divergence is very small. Then, the analyses were conducted for the blade whose conditions are nearer to the critical point. Gradually, divergence of calculation was encountered. Convergence was relatively easy for the modified ideal

  19. Free-stream Turbulence Effects on the Boundary Layer of a High-lift Low-Pressure-Turbine Blade

    Institute of Scientific and Technical Information of China (English)

    Simoni D.; Ubaldi M.; Zunino P.; Ampellio E.

    2016-01-01

    The suction side boundary layer evolution of a high-lift low-pressure turbine cascade has been experimentally investigated at low and high free-stream turbulence intensity conditions.Measurements have been carried out in order to analyze the boundary layer transition and separation processes at a low Reynolds number,under both steady and unsteady inflows.Static pressure distributions along the blade surfaces as well as total pressure distributions in a downstream tangential plane have been measured to evaluate the overall aerodynamic efficiency of the blade for the different conditions.Particle Image Velocimetry has been adopted to analyze the time-mean and time-varying velocity fields.The flow field has been surveyed in two orthogonal planes (a blade-to-blade plane and a wall-parallel one).These measurements allow the identification of the Kelvin-Helmholtz large scale coherent structures shed as a consequence of the boundary layer laminar separation under steady inflow,as well as the investigation of the three-dimensional effects induced by the intermittent passage of low and high speed streaks.A close inspection of the time-mean velocity profiles as well as of the boundary layer integral parameters helps to characterize the suction side boundary layer state,thus justifying the influence of free-stream turbulence intensity on the blade aerodynamic losses measured under steady and unsteady inflows.

  20. Free-stream turbulence effects on the boundary layer of a high-lift low-pressure-turbine blade

    Science.gov (United States)

    Simoni, D.; Ubaldi, M.; Zunino, P.; Ampellio, E.

    2016-06-01

    The suction side boundary layer evolution of a high-lift low-pressure turbine cascade has been experimentally investigated at low and high free-stream turbulence intensity conditions. Measurements have been carried out in order to analyze the boundary layer transition and separation processes at a low Reynolds number, under both steady and unsteady inflows. Static pressure distributions along the blade surfaces as well as total pressure distributions in a downstream tangential plane have been measured to evaluate the overall aerodynamic efficiency of the blade for the different conditions. Particle Image Velocimetry has been adopted to analyze the time-mean and time-varying velocity fields. The flow field has been surveyed in two orthogonal planes (a blade-to-blade plane and a wall-parallel one). These measurements allow the identification of the Kelvin-Helmholtz large scale coherent structures shed as a consequence of the boundary layer laminar separation under steady inflow, as well as the investigation of the three-dimensional effects induced by the intermittent passage of low and high speed streaks. A close inspection of the time-mean velocity profiles as well as of the boundary layer integral parameters helps to characterize the suction side boundary layer state, thus justifying the influence of free-stream turbulence intensity on the blade aerodynamic losses measured under steady and unsteady inflows.

  1. Cooling of gas turbines IX : cooling effects from use of ceramic coatings on water-cooled turbine blades

    Science.gov (United States)

    Brown, W Byron; Livingood, John N B

    1948-01-01

    The hottest part of a turbine blade is likely to be the trailing portion. When the blades are cooled and when water is used as the coolant, the cooling passages are placed as close as possible to the trailing edge in order to cool this portion. In some cases, however, the trailing portion of the blade is so narrow, for aerodynamic reasons, that water passages cannot be located very near the trailing edge. Because ceramic coatings offer the possibility of protection for the trailing part of such narrow blades, a theoretical study has been made of the cooling effect of a ceramic coating on: (1) the blade-metal temperature when the gas temperature is unchanged, and (2) the gas temperature when the metal temperature is unchanged. Comparison is also made between the changes in the blade or gas temperatures produced by ceramic coatings and the changes produced by moving the cooling passages nearer the trailing edge. This comparison was made to provide a standard for evaluating the gains obtainable with ceramic coatings as compared to those obtainable by constructing the turbine blade in such a manner that water passages could be located very near the trailing edge.

  2. Ultimate strength of a large wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Moelholt Jensen, Find

    2008-05-15

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

  3. Quantifying the benefits of a slender, high tip speed blade for large offshore wind turbiness

    Science.gov (United States)

    Blonk, Lindert; Rainey, Patrick; Langston, David A. J.; Vanni, Francesco

    2014-06-01

    An in-depth study has been completed to study the effects of slender, flexible blades in combination with high rotor speed operation on load mitigation, targeted at cost reductions of the structural components of large wind turbines, consequently lowering the levelized cost of energy. An overview of existing theory of sensitivity of turbine fatigue loading to the blade chord and rotor speed was created, and this was supplemented by a proposed theory for aboverated operation including the pitch controller. A baseline jacket-supported offshore turbine (7 MW) was defined, of which the blade was then redesigned to be more slender and flexible, at the same time increasing rotor speed. The blade redesign and optimisation process was guided by cost of energy assessments using a reduced loadset. Thereafter, a full loadset conform IEC61400-3 was calculated for both turbines. The expected support structure load reductions were affirmed, and it was shown that reductions of up to 18.5% are possible for critical load components. Cost modelling indicated that turbine and support structure CapEx could be reduced by 6%. Despite an energy production reduction of 0.44% related to the thicker airfoils used, the blade redesign led to a reduction in Cost of Energy.

  4. Quantifying the benefits of a slender, high tip speed blade for large offshore wind turbiness

    International Nuclear Information System (INIS)

    An in-depth study has been completed to study the effects of slender, flexible blades in combination with high rotor speed operation on load mitigation, targeted at cost reductions of the structural components of large wind turbines, consequently lowering the levelized cost of energy. An overview of existing theory of sensitivity of turbine fatigue loading to the blade chord and rotor speed was created, and this was supplemented by a proposed theory for aboverated operation including the pitch controller. A baseline jacket-supported offshore turbine (7 MW) was defined, of which the blade was then redesigned to be more slender and flexible, at the same time increasing rotor speed. The blade redesign and optimisation process was guided by cost of energy assessments using a reduced loadset. Thereafter, a full loadset conform IEC61400-3 was calculated for both turbines. The expected support structure load reductions were affirmed, and it was shown that reductions of up to 18.5% are possible for critical load components. Cost modelling indicated that turbine and support structure CapEx could be reduced by 6%. Despite an energy production reduction of 0.44% related to the thicker airfoils used, the blade redesign led to a reduction in Cost of Energy

  5. The roles of aerodynamic and inertial forces on maneuverability in flapping flight

    Science.gov (United States)

    Vejdani, Hamid; Boerma, David; Swartz, Sharon; Breuer, Kenneth

    2015-11-01

    We investigate the relative contributions of aerodynamic and the whole-body dynamics in generating extreme maneuvers. We developed a 3D dynamical model of a body (trunk) and two rectangular wings using a Lagrangian formulation. The trunk has 6 degrees of freedom and each wing has 4 degrees of actuation (flapping, sweeping, wing pronation/supination and wing extension/flexion) and can be massless (like insect wings) or relatively massive (like bats). To estimate aerodynamic forces, we use a blade element method; drag and lift are calculated using a quasi-steady model. We validated our model using several benchmark tests, including gliding and hovering motion. To understand the roles of aerodynamic and inertial forces, we start the investigation by constraining the wing motion to flapping and wing length extension/flexion motion. This decouples the trunk degrees of freedom and affects only roll motion. For bats' dynamics (massive wings), the model is much more maneuverable than the insect dynamics case, and the effect of inertial forces dominates the behavior of the system. The role of the aerodynamic forces increases when the wings have sweeping and flapping motion, which affects the pitching motion of the body. We also analyzed the effect of all wing motions together on the behavior of the model in the presence and in the absence of aerodynamic forces.

  6. Analysis of experimental time-dependent blade surface pressures from an oscillating turbine cascade using the influence-coefficient technique

    OpenAIRE

    Fransson, T.

    1992-01-01

    A two-dimensional section of the last stage of a steam turbine blade has been investigated experimentally in an annular non-rotating cascade facility as regards to its steady-state and time-dependent aerodynamic characteristics at design and off-design conditions. The unsteady experimental data obtained with the blades vibrating in the “travelling wave” mode indicate that one of the main reasons for the flutter susceptibility of the cascade lies in the high expansion and following shock wave ...

  7. Fundamentals of modern unsteady aerodynamics

    CERN Document Server

    Gülçat, Ülgen

    2016-01-01

    In this book, the author introduces the concept of unsteady aerodynamics and its underlying principles. He provides the readers with a comprehensive review of the fundamental physics of free and forced unsteadiness, the terminology and basic equations of aerodynamics ranging from incompressible flow to hypersonics. The book also covers modern topics related to the developments made in recent years, especially in relation to wing flapping for propulsion. The book is written for graduate and senior year undergraduate students in aerodynamics and also serves as a reference for experienced researchers. Each chapter includes ample examples, questions, problems and relevant references.   The treatment of these modern topics has been completely revised end expanded for the new edition. It now includes new numerical examples, a section on the ground effect, and state-space representation.

  8. Airfoil family design for large offshore wind turbine blades

    International Nuclear Information System (INIS)

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

  9. The aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming; Troldborg, Niels;

    2013-01-01

    In the paper we present state-of-the-art of research in wind turbine aerodynamics. We start be giving a brief historical review and a survey over aerodynamic research in wind energy. Next, we focus on some recent research results obtained by our wind energy group at Department of Mechanical...... Engineering at DTU. In particular, we show some new results on the classical problem of the ideal rotor and present a series of new results from an on-going research project dealing with the modelling and simulation of turbulent flow structures in the wake behind wind turbines....

  10. Aerodynamic behavior of an airfoil with morphing trailing edge for wind turbine applications

    International Nuclear Information System (INIS)

    The length of wind turbine rotor blades has been increased during the last decades. Higher stresses arise especially at the blade root because of the longer lever arm. One way to reduce unsteady blade-root stresses caused by turbulence, gusts, or wind shear is to actively control the lift in the blade tip region. One promising method involves airfoils with morphing trailing edges to control the lift and consequently the loads acting on the blade. In the present study, the steady and unsteady behavior of an airfoil with a morphing trailing edge is investigated. Two-dimensional Reynolds-Averaged Navier-Stokes (RANS) simulations are performed for a typical thin wind turbine airfoil with a morphing trailing edge. Steady-state simulations are used to design optimal geometry, size, and deflection angles of the morphing trailing edge. The resulting steady aerodynamic coefficients are then analyzed at different angles of attack in order to determine the effectiveness of the morphing trailing edge. In order to investigate the unsteady aerodynamic behavior of the optimal morphing trailing edge, time- resolved RANS-simulations are performed using a deformable grid. In order to analyze the phase shift between the variable trailing edge deflection and the dynamic lift coefficient, the trailing edge is deflected at four different reduced frequencies for each different angle of attack. As expected, a phase shift between the deflection and the lift occurs. While deflecting the trailing edge at angles of attack near stall, additionally an overshoot above and beyond the steady lift coefficient is observed and evaluated

  11. Large, low cost composite wind turbine blades

    Science.gov (United States)

    Gewehr, H. W.

    1979-01-01

    A woven roving E-glass tape, having all of its structural fibers oriented across the tape width was used in the manufacture of the spar for a wind turbine blade. Tests of a 150 ft composite blade show that the transverse filament tape is capable of meeting structural design requirements for wind turbine blades. Composite blades can be designed for interchangeability with steel blades in the MOD-1 wind generator system. The design, analysis, fabrication, and testing of the 150 ft blade are discussed.

  12. Dose optimisation in single plane interstitial brachytherapy

    DEFF Research Database (Denmark)

    Tanderup, Kari; Hellebust, Taran Paulsen; Honoré, Henriette H;

    2006-01-01

    BACKGROUND AND PURPOSE: Brachytherapy dose distributions can be optimised       by modulation of source dwell times. In this study dose optimisation in       single planar interstitial implants was evaluated in order to quantify the       potential benefit in patients. MATERIAL AND METHODS: In 14...

  13. An Optimisation Approach for Room Acoustics Design

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Kirkegaard, Poul Henning; Andersen, Lars

    2005-01-01

    This paper discuss on a conceptual level the value of optimisation techniques in architectural acoustics room design from a practical point of view. It is chosen to optimise one objective room acoustics design criterium estimated from the sound field inside the room. The sound field is modeled...

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    G. Bernardini

    2016-01-01

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

  16. A Study of the Effects of Blade Shape on Rotor Noise

    Science.gov (United States)

    Jones, Henry E.; Burley, Casey L.

    1997-01-01

    A new rotor noise prediction system called the Tiltrotor Aeroacoustic Code (TRAC) has been developed under the Short Haul (Civil Tiltrotor) program between NASA, the Army, and the U.S. helicopter industry. This system couples the comprehensive rotorcraft code CAMRAD.Mod1 with either the high resolution sectional loads code HIRES or the full potential CFD code FPRBVI to predict unsteady blade loads, which are then input to the noise prediction program WOPWOP. In this paper, HIRES will be used to predict the blade-vortex interaction (BVI) noise trends associated with blade shape. The baseline shape selected was a 17% scale model of a contemporary design 4 bladed rotor. Measurements for this rotor were acquired in the Duits-Nederslandse Windtunnel (DNW). The code is used to predict noise for the base configuration and the results are compared to the measured data. This provides a firm foundation for investigating the BVI noise trends associated with blade shape. The shapes selected for study are based on variation of sweep and taper which reflect plausible "passive" design concepts. Comparisons of power required, integrated noise, and aerodynamics are made and important trends are noted.

  17. Engineering models in wind energy aerodynamics: Development, implementation and analysis using dedicated aerodynamic measurements

    NARCIS (Netherlands)

    Schepers, J.G.

    2012-01-01

    The subject of aerodynamics is of major importance for the successful deployment of wind energy. As a matter of fact there are two aerodynamic areas in the wind energy technology: Rotor aerodynamics and wind farm aerodynamics. The first subject considers the flow around the rotor and the second subj

  18. Aerodynamic design and initial performance measurements for the SANDIA 34-metre diameter vertical-axis wind turbine

    Science.gov (United States)

    Berg, Dale E.; Klimas, Paul C.; Stephenson, William A.

    The DOE/Sandia 34-m diameter Vertical-Axis Wind turbine (VAWT) utilizes a step-tapered, multiple-airfoil section blade. One of the airfoil sections is a natural laminar flow profile, the SAND 0018/50, designed specifically for use on VAWTs. The turbine has now been fully operational for more than a year, and extensive turbine aerodynamic performance data have been obtained. This paper reviews the design and fabrication of the rotor blade, with emphasis on the SAND 0018/50 airfoil, and compares the performance measurements to date with the performance predictions. Possible sources of the discrepancies between measured and predicted performance are identified, and plans for additional aerodynamic testing on the turbine are briefly discussed.

  19. CFD calculations on the unsteady aerodynamic characteristics of a tilt-rotor in a conversion mode

    Institute of Scientific and Technical Information of China (English)

    Li Peng; Zhao Qijun; Zhu Qiuxian

    2015-01-01

    In order to calculate the unsteady aerodynamic characteristics of a tilt-rotor in a conver-sion mode, a virtual blade model (VBM) and an real blade model (RBM) are established respec-tively. A new multi-layer moving-embedded grid technique is proposed to reduce the numerical dissipation of the tilt-rotor wake in a conversion mode. In this method, a grid system generated abound the rotor accounts for rigid blade motions, and a new searching scheme named adaptive inverse map (AIM) is established to search corresponding donor elements in the present moving-embedded grid system to translate information among the different computational zones. A dual-time method is employed to fulfill unsteady calculations on the flowfield of the tilt-rotor, and a second-order centered difference scheme considering artificial viscosity is used to calculate the flux. In order to improve the computing efficiency, the single program multiple data (SPMD) model parallel acceleration technology is adopted, according to the characteristic of the current grid system. The lift and drag coefficients of an NACA0012 airfoil, the dynamic pressure distributions below a typical rotor plane, and the sectional pressure distributions on a three-bladed Branum–Tung tilt-rotor in hover flight are calculated respectively, and the present VBM and RBM are val-idated by comparing the calculated results with available experimental data. Then, unsteady aero-dynamic forces and flowfields of an XV-15 tilt-rotor in different modes, such as a fixed conversion mode at different tilt angles (15?, 30?, 60?) and a whole conversion mode which converses from 0? to 90?, are numerically simulated by the VBM and RBM respectively. By analyses and comparisons on the simulated results of unsteady aerodynamic forces of the tilt-rotor in different modes, some meaningful conclusions about distorted blade-tip vortex distribution and unsteady aerodynamic force variation in a conversion mode are obtained, and these investigation

  20. Unsteady aerodynamics modeling for flight dynamics application

    Science.gov (United States)

    Wang, Qing; He, Kai-Feng; Qian, Wei-Qi; Zhang, Tian-Jiao; Cheng, Yan-Qing; Wu, Kai-Yuan

    2012-02-01

    In view of engineering application, it is practicable to decompose the aerodynamics into three components: the static aerodynamics, the aerodynamic increment due to steady rotations, and the aerodynamic increment due to unsteady separated and vortical flow. The first and the second components can be presented in conventional forms, while the third is described using a one-order differential equation and a radial-basis-function (RBF) network. For an aircraft configuration, the mathematical models of 6-component aerodynamic coefficients are set up from the wind tunnel test data of pitch, yaw, roll, and coupled yawroll large-amplitude oscillations. The flight dynamics of an aircraft is studied by the bifurcation analysis technique in the case of quasi-steady aerodynamics and unsteady aerodynamics, respectively. The results show that: (1) unsteady aerodynamics has no effect upon the existence of trim points, but affects their stability; (2) unsteady aerodynamics has great effects upon the existence, stability, and amplitudes of periodic solutions; and (3) unsteady aerodynamics changes the stable regions of trim points obviously. Furthermore, the dynamic responses of the aircraft to elevator deflections are inspected. It is shown that the unsteady aerodynamics is beneficial to dynamic stability for the present aircraft. Finally, the effects of unsteady aerodynamics on the post-stall maneuverability are analyzed by numerical simulation.

  1. Unsteady aerodynamics modeling for flight dynamics application

    Institute of Scientific and Technical Information of China (English)

    Qing Wang; Kai-Feng He; Wei-Qi Qian; Tian-Jiao Zhang; Yan-Qing Cheng; Kai-Yuan Wu

    2012-01-01

    In view of engineering application,it is practicable to decompose the aerodynamics into three components:the static aerodynamics,the aerodynamic increment due to steady rotations,and the aerodynamic increment due to unsteady separated and vortical flow.The first and the second components can be presented in conventional forms,while the third is described using a one-order differential equation and a radial-basis-function (RBF) network. For an aircraft configuration,the mathematical models of 6-component aerodynamic coefficients are set up from the wind tunnel test data of pitch,yaw,roll,and coupled yawroll large-amplitude oscillations.The flight dynamics of an aircraft is studied by the bifurcation analysis technique in the case of quasi-steady aerodynamics and unsteady aerodynamics,respectively.The results show that:(1) unsteady aerodynamics has no effect upon the existence of trim points,but affects their stability; (2) unsteady aerodynamics has great effects upon the existence,stability,and amplitudes of periodic solutions; and (3) unsteady aerodynamics changes the stable regions of trim points obviously.Furthermore,the dynamic responses of the aircraft to elevator deflections are inspected.It is shown that the unsteady aerodynamics is beneficial to dynamic stability for the present aircraft.Finally,the effects of unsteady aerodynamics on the post-stall maneuverability are analyzed by numerical simulation.

  2. Influence of Helicopter Rotor Wake Modeling on Blade Airload Predictions

    Directory of Open Access Journals (Sweden)

    Christos K. Zioutis

    2010-01-01

    Full Text Available In the present paper a computational investigation is made about the efficiency ofrecently developed mathematical models for specific aerodynamic phenomena ofthe complicated helicopter rotor flowfield. A developed computational procedureis used, based on a Lagrangian type, Vortex Element Method. The free vorticalwake geometry and rotor airloads are computed. The efficiency of special modelsconcerning vortex core structure, vorticity diffusion and vortex straining regardingrotor airloads prediction is tested. Investigations have also been performed inorder to assess a realistic value for empirical factors included in vorticity diffusionmodels. The benefit of using multiple vortex line to simulate trailing wake vorticitybehind blade span instead of isolated lines or vortex sheets, despite theircomputational cost, is demonstrated with the developed wake relaxation method.The computational results are compared with experimental data from wind tunneltests, performed during joined European research programs.

  3. Multi-Body Unsteady Aerodynamics in 2D Applied to aVertical-Axis Wind Turbine Using a Vortex Method

    OpenAIRE

    Österberg, David

    2010-01-01

    Vertical axis wind turbines (VAWT) have many advantages over traditional Horizontalaxis wind turbines (HAWT).One of the more severe problem of VAWTs are the complicated aerodynamicbehavior inherent in the concept. Incontrast to HAWTs the blades experience varying angle of attack during its orbitalmotion. The unsteady flowleads to unsteady loads, and hence, to increased risk for problems with fatigue.A tool for aerodynamic analysis of vertical axis wind turbines has been developed.The model, a...

  4. Nostril Aerodynamics of Scenting Animals

    Science.gov (United States)

    Settles, G. S.

    1997-11-01

    Dogs and other scenting animals detect airborne odors with extraordinary sensitivity. Aerodynamic sampling plays a key role, but the literature on olfaction contains little on the external aerodynamics thereof. To shed some light on this, the airflows generated by a scenting dog were visualized using the schlieren technique. It was seen that the dog stops panting in order to scent, since panting produces a turbulent jet which disturbs scent-bearing air currents. Inspiratory airflow enters the nostrils from straight ahead, while expiration is directed to the sides of the nose and downward, as was found elsewhere in the case of rats and rabbits. The musculature and geometry of the dog's nose thus modulates the airflow during scenting. The aerodynamics of a nostril which must act reversibly as both inlet and outlet is briefly discussed. The eventual practical goal of this preliminary work is to achieve a level of understanding of the aerodynamics of canine olfaction sufficient for the design of a mimicking device. (Research supported by the DARPA Unexploded Ordnance Detection and Neutralization Program.)

  5. Aerodynamic design via control theory

    Science.gov (United States)

    Jameson, Antony

    1988-01-01

    The question of how to modify aerodynamic design in order to improve performance is addressed. Representative examples are given to demonstrate the computational feasibility of using control theory for such a purpose. An introduction and historical survey of the subject is included.

  6. Optimising costs in WLCG operations

    CERN Document Server

    Pradillo, Mar; Flix, Josep; Forti, Alessandra; Sciabà, Andrea

    2015-01-01

    The Worldwide LHC Computing Grid project (WLCG) provides the computing and storage resources required by the LHC collaborations to store, process and analyse the 50 Petabytes of data annually generated by the LHC. The WLCG operations are coordinated by a distributed team of managers and experts and performed by people at all participating sites and from all the experiments. Several improvements in the WLCG infrastructure have been implemented during the first long LHC shutdown to prepare for the increasing needs of the experiments during Run2 and beyond. However, constraints in funding will affect not only the computing resources but also the available effort for operations. This paper presents the results of a detailed investigation on the allocation of the effort in the different areas of WLCG operations, identifies the most important sources of inefficiency and proposes viable strategies for optimising the operational cost, taking into account the current trends in the evolution of the computing infrastruc...

  7. optimised observables in the MSSM

    Science.gov (United States)

    Mahmoudi, Farvah; Neshatpour, Siavash; Virto, Javier

    2014-06-01

    We provide a detailed analysis of the impact of the newly measured optimised observables in the decay by the LHCb experiment. The analysis is performed in the MSSM, both in the context of the usual constrained scenarios and in the context of a more general set-up where the SUSY partner masses are independent. We show that the global agreement of the MSSM solutions with the data is still very good. Nevertheless, especially in the constrained scenarios, the limits from are now very strong and are at the same level as the well-known constraints. We describe the implications of the measurements both on the Wilson coefficients and on the SUSY parameters.

  8. Fluid Mechanics Optimising Organic Synthesis

    Science.gov (United States)

    Leivadarou, Evgenia; Dalziel, Stuart

    2015-11-01

    The Vortex Fluidic Device (VFD) is a new ``green'' approach in the synthesis of organic chemicals with many industrial applications in biodiesel generation, cosmetics, protein folding and pharmaceutical production. The VFD is a rapidly rotating tube that can operate with a jet feeding drops of liquid reactants to the base of the tube. The aim of this project is to explain the fluid mechanics of the VFD that influence the rate of reactions. The reaction rate is intimately related to the intense shearing that promotes collision between reactant molecules. In the VFD, the highest shears are found at the bottom of the tube in the Rayleigh and the Ekman layer and at the walls in the Stewardson layers. As a step towards optimising the performance of the VFD we present experiments conducted in order to establish the minimum drop volume and maximum rotation rate for maximum axisymmetric spreading without fingering instability. PhD candidate, Department of Applied Mathematics and Theoretical Physics.

  9. Use of blade lean in turbomachinery redesign

    Science.gov (United States)

    Moore, John; Moore, Joan G.; Lupi, Alex

    1993-07-01

    Blade lean is used to improve the uniformity of exit flow distributions from turbomachinery blading. In turbines, it has been used to control secondary flows by tailoring blade turning to reduce flow overturning and underturning and to create more uniform loss distributions from hub to shroud. In the present study, the Pump Consortium centrifugal impeller has been redesigned using blade lean. The flow at the exit of the baseline impeller had large blade-to-blade variations, creating a highly unsteady flow for the downstream diffuser. Blade lean is used to redesign the flow to move the high loss fluid from the suction side to the hub, significantly reducing blade-toblade variations at the exit.

  10. Optimising code generation with haggies

    Science.gov (United States)

    Reiter, T.

    2010-07-01

    This article describes haggies, a program for the generation of optimised programs for the efficient numerical evaluation of mathematical expressions. It uses a multivariate Horner-scheme and Common Subexpression Elimination to reduce the overall number of operations. The package can serve as a back-end for virtually any general purpose computer algebra program. Built-in type inference that allows to deal with non-standard data types in strongly typed languages and a very flexible, pattern-based output specification ensure that haggies can produce code for a large variety of programming languages. We currently use haggies as part of an automated package for the calculation of one-loop scattering amplitudes in quantum field theories. The examples in this articles, however, demonstrate that its use is not restricted to the field of high energy physics. Program summaryProgram title: haggies Catalogue identifier: AEGF_v1_0 Program summary: URL: http://cpc.cs.qub.ac.uk/summaries/AEGF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL v3 No. of lines in distributed program, including test data, etc.: 56 220 No. of bytes in distributed program, including test data, etc.: 579 010 Distribution format: tar.gz Programming language: Java, JavaCC Computer: Any system that runs the Java Virtual Machine Operating system: Any system that runs the Java Virtual Machine RAM: Determined by the size of the problem Classification: 4.14, 5, 6.2, 6.5, 11.1 Nature of problem: Generation of optimised programs for the evaluation of possibly large algebraic expressions Solution method: Java implementation Running time: Determined by the size of the problem

  11. 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.

  12. Design of PVC Bladed Horizontal Axis Wind Turbine for Low Wind Speed Region

    Directory of Open Access Journals (Sweden)

    Vicky K Rathod

    2014-07-01

    Full Text Available The Project is aimed at designing a wind turbine that can be able to build by Laypersons, using readily available material which is feasible & affordable to provide much needed electricity. Since most of the high wind power density regions in the zone of high wind speed are already being tapped by large scale wind turbine and so it required creating a large scope for the development of low wind speed turbines. Our study focuses primarily on designing the blade for tapping power in the regions of low wind power density. The aerodynamic profiles of wind turbine blades have major influence on aerodynamic efficiency of wind turbine. This can be achieved by comparing the effectiveness of a crude blade fashioned from a different Size, Material & standard of PVC drainage pipe which are easily available in market. It can be evaluated by performing experimental analysis, data collection & its evaluation on different type & size of PVC Pipe & preparing an analytical tool for best Design.

  13. Forward sweep, low noise rotor blade

    Science.gov (United States)

    Brooks, Thomas F. (Inventor)

    1996-01-01

    A forward-swept, low-noise rotor blade includes an inboard section, an aft-swept section and a forward-swept outboard section. The rotor blade reduces the noise of rotorcraft, including both standard helicopters and advanced systems such as tiltrotors. The primary noise reduction feature is the forward sweep of the planform over a large portion of the outer blade radius. The rotor blade also includes an aft-swept section. The purpose of the aft-swept region is to provide a partial balance to pitching moments produced by the outboard forward-swept portion of the blade. The rotor blade has a constant chord width; or has a chord width which decreases linearly along the entire blade span; or combines constant and decreasing chord widths, wherein the blade is of constant chord width from the blade root to a certain location on the rotor blade, then decreases linearly to the blade tip thereafter. The noise source showing maximum noise reduction is blade-vortex interaction (BVI) noise. Also reduced are thickness, noise, high speed impulsive noise, cabin vibration and loading noise.

  14. Computer Program Aids Design Of Impeller Blades

    Science.gov (United States)

    Chen, Wei-Chung; Galazin, John V.

    1992-01-01

    Impeller blades for centrifugal turbopumps designed quickly with help of computer program. Generates blade contours and continually subjects them to evaluation. Checks physical parameters to ensure they are compatible with required performance and recycles design if criteria not met. Program written for centrifugal turbomachinery, also adapted to such axial pump components as inducer blades and stator vanes.

  15. Experimental characterization of high speed centrifugal compressor aerodynamic forcing functions

    Science.gov (United States)

    Gallier, Kirk

    The most common and costly unexpected post-development gas turbine engine reliability issue is blade failure due to High Cycle Fatigue (HCF). HCF in centrifugal compressors is a coupled nonlinear fluid-structure problem for which understanding of the phenomenological root causes is incomplete. The complex physics of this problem provides significant challenges for Computational Fluid Dynamics (CFD) techniques. Furthermore, the available literature fails to address the flow field associated with the diffuser potential field, a primary cause of forced impeller vibration. Because of the serious nature of HCF, the inadequacy of current design approaches to predict HCF, and the fundamental lack of benchmark experiments to advance the design practices, there exists a need to build a database of information specific to the nature of the diffuser generated forcing function as a foundation for understanding flow induced blade vibratory failure. The specific aim of this research is to address the fundamental nature of the unsteady aerodynamic interaction phenomena inherent in high-speed centrifugal compressors wherein the impeller exit flow field is dynamically modulated by the vaned diffuser potential field or shock structure. The understanding of this unsteady aerodynamic interaction is fundamental to characterizing the impeller forcing function. Unsteady static pressure measurement at several radial and circumferential locations in the vaneless space offer a depiction of pressure field radial decay, circumferential variation and temporal fluctuation. These pressure measurements are coupled with high density, full field measurement of the velocity field within the diffuser vaneless space at multiple spanwise positions. The velocity field and unsteady pressure field are shown to be intimately linked. A strong momentum gradient exiting the impeller is shown to extend well across the vaneless space and interact with the diffuser vane leading edge. The deterministic unsteady

  16. Morping blade design for vertical axis wind turbines

    Science.gov (United States)

    Macphee, David; Beyene, Asfaw

    2015-11-01

    Wind turbines operate at peak efficiency at a certain set of operational conditions. Away from these conditions, conversion efficiency drops significantly, requiring pitch and yaw control schemes to mitigate these losses. These efforts are an example of geometric variability, allowing for increased power production but with an unfortunate increase in investment cost to the energy conversion system. In Vertical-Axis Wind Turbines (VAWTs), the concept of pitch control is especially complicated due to a dependence of attack angle on armature azimuth. As a result, VAWT pitch control schemes, both active and passive, are as of yet unfeasible. This study investigates a low-cost, passive pitch control system, in which VAWT blades are constructed of a flexible material, allowing for continuous shape-morphing in response to local aerodynamic loading. This design is analyzed computationally using a finite-volume fluid-structure interaction routine and compared to a geometrically identical rigid rotor. The results indicate that the flexible blade increases conversion efficiency by reducing the severity of vortex shedding, allowing for greater average torque over a complete revolution.

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

    Science.gov (United States)

    Malpica, Carlos; Greenwood, Eric; Sim, Ben

    2016-01-01

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

  18. Aerodynamic wind-turbine rotor design using surrogate modeling and three-dimensional viscous-inviscid interaction technique

    DEFF Research Database (Denmark)

    Sessarego, Matias; Ramos García, Néstor; Yang, Hua; Shen, Wen Zhong

    2016-01-01

    In this paper a surrogate optimization methodology using a three-dimensional viscous-inviscid interaction code for the aerodynamic design of wind-turbine rotors is presented. The framework presents aunique approach because it does not require the commonly-used blade element momentum (BEM...... identical aerodynamic performance can be achieved using the new design method and that themethodology is effective for the aerodynamic design of wind-turbine rotors....... instead of an inexpensive BEM code represents a challenge, which is resolved by using theproposed surrogate-based approach. As a verification case, the methodology is applied to design a modelwind-turbine rotor and is compared in detail with the one designed with BEM. Results demonstrate thatnearly...

  19. COBSTRAN - COMPOSITE BLADE STRUCTURAL ANALYZER

    Science.gov (United States)

    Aiello, R. A.

    1994-01-01

    The COBSTRAN (COmposite Blade STRuctural ANalyzer) program is a pre- and post-processor that facilitates the design and analysis of composite turbofan and turboprop blades, as well as composite wind turbine blades. COBSTRAN combines composite mechanics and laminate theory with a data base of fiber and matrix properties. As a preprocessor for NASTRAN or another Finite Element Method (FEM) program, COBSTRAN generates an FEM model with anisotropic homogeneous material properties. Stress output from the FEM program is provided as input to the COBSTRAN postprocessor. The postprocessor then uses the composite mechanics and laminate theory routines to calculate individual ply stresses, strains, interply stresses, thru-the-thickness stresses and failure margins. COBSTRAN is designed to carry out the many linear analyses required to efficiently model and analyze blade-like structural components made of multilayered angle-plied fiber composites. Components made from isotropic or anisotropic homogeneous materials can also be modeled as a special case of COBSTRAN. NASTRAN MAT1 or MAT2 material cards are generated according to user supplied properties. COBSTRAN is written in FORTRAN 77 and was implemented on a CRAY X-MP with a UNICOS 5.0.12 operating system. The program requires either COSMIC NASTRAN or MSC NASTRAN as a structural analysis package. COBSTRAN was developed in 1989, and has a memory requirement of 262,066 64 bit words.

  20. Running excitation of blades bunches

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    Praha: Institute of Thermomechanics AS CR, 2014 - (Zolotarev, I.; Pešek, L.), s. 45-52 ISBN 978-80-87012-54-3. [DYMAMESI 2014. Praha (CZ), 25.11.2014-26.11.2014] Institutional support: RVO:61388998 Keywords : damping * dry friction * five-blades-bunch * delayed harmonic excitation Subject RIV: BI - Acoustics

  1. Heat Transfer and Flow on the First Stage Blade Tip of a Power Generation Gas Turbine. Part 1; Experimental Results

    Science.gov (United States)

    Bunker, Ronald S.; Bailey, Jeremy C.; Ameri, Ali A.

    1999-01-01

    A combined computational and experimental study has been performed to investigate the detailed distribution of convective heat transfer coefficients on the first stage blade tip surface for a geometry typical of large power generation turbines(>100MW). This paper is concerned with the design and execution of the experimental portion of the study. A stationary blade cascade experiment has been run consisting of three airfoils, the center airfoil having a variable tip gap clearance. The airfoil models the aerodynamic tip section of a high pressure turbine blade with inlet Mach number of 0.30, exit Mach number of 0.75, pressure ratio of 1.45, exit Reynolds number based on axial chord of 2.57 x 10(exp 6), and total turning of about 110 degrees. A hue detection based liquid crystal method is used to obtain the detailed heat transfer coefficient distribution on the blade tip surface for flat, smooth tip surfaces with both sharp and rounded edges. The cascade inlet turbulence intensity level took on values of either 5% or 9%. The cascade also models the casing recess in the shroud surface ahead of the blade. Experimental results are shown for the pressure distribution measurements on the airfoil near the tip gap, on the blade tip surface, and on the opposite shroud surface. Tip surface heat transfer coefficient distributions are shown for sharp-edge and rounded-edge tip geometries at each of the inlet turbulence intensity levels.

  2. Combining simulation and multi-objective optimisation for equipment quantity optimisation in container terminals

    OpenAIRE

    Lin, Zhougeng

    2013-01-01

    This thesis proposes a combination framework to integrate simulation and multi-objective optimisation (MOO) for container terminal equipment optimisation. It addresses how the strengths of simulation and multi-objective optimisation can be integrated to find high quality solutions for multiple objectives with low computational cost. Three structures for the combination framework are proposed respectively: pre-MOO structure, integrated MOO structure and post-MOO structure. The applications of ...

  3. Turbine blade tip gap reduction system

    Science.gov (United States)

    Diakunchak, Ihor S.

    2012-09-11

    A turbine blade sealing system for reducing a gap between a tip of a turbine blade and a stationary shroud of a turbine engine. The sealing system includes a plurality of flexible seal strips extending from a pressure side of a turbine blade generally orthogonal to the turbine blade. During operation of the turbine engine, the flexible seal strips flex radially outward extending towards the stationary shroud of the turbine engine, thereby reducing the leakage of air past the turbine blades and increasing the efficiency of the turbine engine.

  4. Topology Optimisation for Coupled Convection Problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe

    This thesis deals with topology optimisation for coupled convection problems. The aim is to extend and apply topology optimisation to steady-state conjugate heat transfer problems, where the heat conduction equation governs the heat transfer in a solid and is coupled to thermal transport...... in a surrounding uid, governed by a convection-diffusion equation, where the convective velocity field is found from solving the isothermal incompressible steady-state Navier-Stokes equations. Topology optimisation is also applied to steady-state natural convection problems. The modelling is done using stabilised...... finite elements, the formulation and implementation of which was done partly during a special course as prepatory work for this thesis. The formulation is extended with a Brinkman friction term in order to facilitate the topology optimisation of fluid flow and convective cooling problems. The derived...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    constraints. In addition, a buckling analysis is performed at the fine description level, which in turn affects the nonstructural blade mass. The updated constraint bounds and mass make their effects felt at the next coarse-level constrained design optimization, thereby closing the loop between the coarse and......The present work describes a method for the structural optimization of wind turbine rotor blades for given prescribed aerodynamic shape. The proposed approach operates at various description levels producing cost-minimizing solutions that satisfy desired design constraints at the finest modeling...... fine description levels. The multilevel optimization procedure is implemented in a computer program and it is demonstrated on the design of a multi-MW horizontal axis wind turbine rotor blade. © 2013 Springer Science+Business Media Dordrecht....

  6. Structural Optimization of Wind Turbine Rotor Blades by Multi-Level Sectional/Multibody/3DFEM Analysis

    DEFF Research Database (Denmark)

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

    constraints. In addition, a buckling analysis is performed at the fine description level, which in turn affects the non-structural blade mass. The updated constraint bounds and mass make their effects felt at the next coarse-level constrained design optimization, thereby closing the loop between the coarse......The present work describes a method for the structural optimization of wind turbine rotor blades for given prescribed aerodynamic shape. The proposed approach operates at various description levels producing cost-minimizing solutions that satisfy desired design constraints at the finest modeling...... and fine description levels. The multi-level optimization procedure is implemented in a computer program and it is demonstrated on the design of a multi-MW horizontal axis wind turbine rotor blade....

  7. Development and Validation of a New Blade Element Momentum Skewed-Wake Model within AeroDyn: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Ning, S. A.; Hayman, G.; Damiani, R.; Jonkman, J.

    2014-12-01

    Blade element momentum methods, though conceptually simple, are highly useful for analyzing wind turbines aerodynamics and are widely used in many design and analysis applications. A new version of AeroDyn is being developed to take advantage of new robust solution methodologies, conform to a new modularization framework for National Renewable Energy Laboratory's FAST, utilize advanced skewed-wake analysis methods, fix limitations with previous implementations, and to enable modeling of highly flexible and nonstraight blades. This paper reviews blade element momentum theory and several of the options available for analyzing skewed inflow. AeroDyn implementation details are described for the benefit of users and developers. These new options are compared to solutions from the previous version of AeroDyn and to experimental data. Finally, recommendations are given on how one might select from the various available solution approaches.

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

    Directory of Open Access Journals (Sweden)

    Eduard Dyachuk

    2015-10-01

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

  9. 3D Navier-Stokes Simulations of a rotor designed for Maximum Aerodynamic Efficiency

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Madsen, Helge. Aa.; Gaunaa, Mac; Bak, Christian; Sørensen, Niels

    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...... constant load was assumed. The rotor design was obtained using an Actuator Disc model and was subsequently verified using both a free wake Lifting Line method and a full 3D Navier-Stokes solver. Excellent agreement was obtained using the three models. Global mechanical power coefficient, CP, reached a...... value of slightly above 0.51, while global thrust coefficient, CT, was 0.87. The local power coefficient, Cp, increased to slightly above the Betz limit on the inner part of the rotor as well as the local thrust coefficient, Ct, increased to a value above 1.1. This agrees well with the theory of de...

  10. An Aerodynamic Method for the Preliminary Design of Horizontal Axis Wind Turbines

    Directory of Open Access Journals (Sweden)

    X. Munduate

    2000-01-01

    Full Text Available The present paper describes a method developed to assist in the preliminary aerodynamic design of wind turbines by identifying regions of the rotor disk which are dominated by unsteady and/or three-dimensional effects. The technique is based on a blade element/momentum predictor that has been extended to consider yawed flow and tower shadow effects. In addition, the method tracks temporal changes in blade incidence to identify regions of the rotor disk which are susceptible to dynamic stall. It also monitors and assesses the severity of three-dimensional stall delay and the extent to which this interacts with the regions of unsteadiness. In the paper the capability of the method will be demonstrated by application to the specific test case of the U. S. National Renewable Energy Laboratories (NREL Combined Experiment turbine.

  11. EXPERIMENTAL INVESTIGATION OF AERODYNAMIC INTERACTION EFFECT OF ROTOR WAKE ON FUSELAGE OF HELICOPTER

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The interaction effect of rotor wake on fuselage of helicopter was investigated with experimental method. The results from experiment have proved that for the drag of fuselage the effect of rotor airflow is closely in connection with both the flight speed and the collective pitch of blades, while for the thrust and pitch moment of fuselage the collective pitch angle of blades plays more important role. A simple and effective computing method about aerodynamic interaction can be derived from the measured data. In order to implement the experiment, a fuselage model, a special sensor, the measurement and data acquisition and processing system were designed and manufactured according to the special requirements of this research project, thereby a good base was built up for carrying out experiments successfully with high quality.

  12. 3D pressure imaging of an aircraft propeller blade-tip flow by phase-locked stereoscopic PIV

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-02-15

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

  13. Development and Evaluation of an Aerodynamic Model for a Novel Vertical Axis Wind Turbine Concept

    Directory of Open Access Journals (Sweden)

    Andrew Shires

    2013-05-01

    Full Text Available There has been a resurgence of interest in the development of vertical axis wind turbines which have several inherent attributes that offer some advantages for offshore operations, particularly their scalability and low over-turning moments with better accessibility to drivetrain components. This paper describes an aerodynamic performance model for vertical axis wind turbines specifically developed for the design of a novel offshore V-shaped rotor with multiple aerodynamic surfaces. The model is based on the Double-Multiple Streamtube method and includes a number of developments for alternative complex rotor shapes. The paper compares predicted results with measured field data for five different turbines with both curved and straight blades and rated powers in the range 100–500 kW. Based on these comparisons, the paper proposes modifications to the Gormont dynamic stall model that gives improved predictions of rotor power for the turbines considered.

  14. Analysis of wind turbine aerodynamics and aeroelasticity using vortex-based methods

    DEFF Research Database (Denmark)

    Branlard, Emmanuel Simon Pierre

    have regained interest in wind energy applications over the last two decades. The current work derives and illustrates some of the potential benefits of vortex-based analyses. The two key wake geometries used in this study to derive simple vortex models are the cylindrical and helical wake models. Both......Momentum analysis through Blade Element Momentum (BEM) and Computational Fluid Dynamics (CFD) are the two major paths commonly followed for wind turbine aerodynamic and aeroelastic research. Instead, the current PhD thesis focuses on the application of vortex-based methods. Vortex-based methods are...... be used in BEM implementations. The current thesis also presents the implementation of a vortex code to further investigate wind turbine aerodynamics. The code consists of both low-order and high-order formulations. The implementation features are described and illustrated through different...

  15. Assessment of 3D aerodynamic effects on the behaviour of floating wind turbines

    Science.gov (United States)

    Manolas, D.; Riziotis, V.; Voutsinas, S.

    2014-12-01

    Current state-of-art models for floating wind turbines are built by merging separate modules addressing the four basic aspects leading to a compound hydro-servo-aero-elastic time domain solver. While current state-of-the-art models differ in many aspects, they all use the blade element momentum (BEM) aerodynamic modelling. Due to its low cost, BEM is the standard choice for design purposes. However the use of BEM entails several semi-empirical corrections and add-ons that need reconsideration and recalibration when new features appear. For floating wind turbines, the effect of the floater motions is such a new feature. In the present paper, this aspect is investigated by comparing BEM based results against 3D free-wake simulations. Deterministic as well as stochastic simulations are presented in pure aerodynamic and full aeroelastic context. It is confirmed that asymmetric inflow originating from yaw misalignment and shear give significant differences reflected on mean values and amplitudes.

  16. Assessment of 3D aerodynamic effects on the behaviour of floating wind turbines

    International Nuclear Information System (INIS)

    Current state-of-art models for floating wind turbines are built by merging separate modules addressing the four basic aspects leading to a compound hydro-servo-aero-elastic time domain solver. While current state-of-the-art models differ in many aspects, they all use the blade element momentum (BEM) aerodynamic modelling. Due to its low cost, BEM is the standard choice for design purposes. However the use of BEM entails several semi-empirical corrections and add-ons that need reconsideration and recalibration when new features appear. For floating wind turbines, the effect of the floater motions is such a new feature. In the present paper, this aspect is investigated by comparing BEM based results against 3D free-wake simulations. Deterministic as well as stochastic simulations are presented in pure aerodynamic and full aeroelastic context. It is confirmed that asymmetric inflow originating from yaw misalignment and shear give significant differences reflected on mean values and amplitudes

  17. An Innovative Design of a Microtab Deployment Mechanism for Active Aerodynamic Load Control

    Directory of Open Access Journals (Sweden)

    Kuo-Chang Tsai

    2015-06-01

    Full Text Available This study presents an innovative design of a microtab system for aerodynamic load control on horizontal-axis wind-turbine rotors. Microtabs are small devices located near the trailing edge of the rotor blades and enable a rapid increase or decrease of the lift force through deployment of the tabs on the pressure or suction side of the airfoil, respectively. The new system has been designed to replace an earlier linearly-actuated microtab mechanism whose performance was limited by space restrictions and stiction. The newly-designed microtab system is based on a four-bar linkage that overcomes the two drawbacks. Its improved kinematics allows for the tab height to increase from 1.0% to 1.7% of the airfoil chord when fully deployed, thereby making it more effective in terms of aerodynamic load control. Furthermore, the modified four-bar link mechanism provides a more robust and reliable mechanical structure.

  18. Experimental characterization of airfoil boundary layers for improvement of aeroacoustic and aerodynamic modeling

    DEFF Research Database (Denmark)

    Fischer, Andreas

    2011-01-01

    and to improve it, because the predictions gave in general too low far field noise levels. Our main finding is that the acoustic formulations to relate the fluctuating surface pressure field close to the trailing edge of airfoil to the radiated far field sound give excellent results when compared to far field......The present work aims at the characterization of aerodynamic noise from wind turbines. There is a consensus among scientists that the dominant aerodynamic noise mechanism is turbulent boundary trailing edge noise. In almost all operational conditions the boundary layer flow over the wind turbine...... blades makes a transition from laminar to turbulent. In the turbulent boundary layer eddies are created which are a potential noise sources. They are ineffective as noise source on the airfoil surface or in free flow, but when convecting past the trailing edge of the airfoil their efficiency is much...

  19. Methodological principles for optimising functional MRI experiments

    International Nuclear Information System (INIS)

    Functional magnetic resonance imaging (fMRI) is one of the most common methods for localising neuronal activity in the brain. Even though the sensitivity of fMRI is comparatively low, the optimisation of certain experimental parameters allows obtaining reliable results. In this article, approaches for optimising the experimental design, imaging parameters and analytic strategies will be discussed. Clinical neuroscientists and interested physicians will receive practical rules of thumb for improving the efficiency of brain imaging experiments. (orig.)

  20. User perspectives in public transport timetable optimisation

    DEFF Research Database (Denmark)

    Jensen, Jens Parbo; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2014-01-01

    The present paper deals with timetable optimisation from the perspective of minimising the waiting time experienced by passengers when transferring either to or from a bus. Due to its inherent complexity, this bi-level minimisation problem is extremely difficult to solve mathematically, since tim...... applied on the large-scale public transport network in Denmark. The timetable optimisation approach yielded a yearly reduction in weighted waiting time equivalent to approximately 45 million Danish kroner (9 million USD)....