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Sample records for blade trailing edge

  1. Development of smart blade technology - trailing edge flaps

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge

    2014-01-01

    With blade lengths presently up to 80+ m there is a need for a supplement to the standard pitch system for control of power and loads. Distributed load control along the blade span with trailing edge flaps is a promising concept where numerical simulations have shown considerable load alleviation...

  2. 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...

  3. Trailing edge noise theory for rotating blades in uniform flow

    CERN Document Server

    Sinayoko, Samuel; Agarwal, Anurag

    2013-01-01

    This paper presents a new formulation for trailing edge noise radiation from rotating blades based on an analytical solution of the convective wave equation. It accounts for distributed loading and the effect of mean flow and spanwise wavenumber. A commonly used theory due to Schlinker and Amiet (1981) predicts trailing edge noise radiation from rotating blades. However, different versions of the theory exist; it is not known which version is the correct one and what the range of validity of the theory is. This paper addresses both questions by deriving Schlinker and Amiet's theory in a simple way and by comparing it to the new formulation, using model blade elements representative of a wind turbine, a cooling fan and an aircraft propeller. The correct form of Schlinker and Amiet's theory (1981) is identified. It is valid at high enough frequency, i.e. for a Helmholtz number relative to chord greater than one and a rotational frequency much smaller than the angular frequency of the noise sources.

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

    DEFF Research Database (Denmark)

    Castaignet, Damien Bruno

    with three trailing edge flaps on one blade, located on DTU’s Risø Campus in Roskilde, Denmark. This thesis is divided into three parts: the controller design, results from simulations, and results from the experiments. The trailing edge flaps controller designed for this project is based on a frequency......, in Roskilde, Denmark. One blade of the turbine was equipped with three independent trailing edge flaps. In spite of the failure of several sensors and actuators, the test of the trailing edge flaps controller described in this thesis showed a consistent flapwise blade root fatigue load reduction. An average...

  5. 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.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  7. Failures in Trailing Edge Bondlines of Wind Turbine Blades

    DEFF Research Database (Denmark)

    Jensen, F. M.; Sørensen, John Dalsgaard; Nielsen, P. H.;

    2011-01-01

    constitute a significant part of the cost per kWh produced. However, the wind turbine industy is reluctant to share statistical values for damages, and this makes it more difficult to assess the reliability. Instead of analyzing the joint and reinforce the connection, research at Risø DTU has shown, that it...... possible to reduce the deformation of the trailing edge panels and thereby reduce the peeling stresses in the trailing edge joint. A basic solution patented by Risø DTU is presented. The research is based on a combination of numerical analysis and full-scale testing. The research has shown the need for...

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

    DEFF Research Database (Denmark)

    Haselbach, Philipp Ulrich; Branner, Kim

    2016-01-01

    non-linear buckling effect of the trailing edge under combined loading, and how it affects the ultimate strength of a blade in a trailing-edge failure dominated load direction were investigated. The study details the interaction between trailing edge buckling on damage onset and sandwich panel failure......The reliability and accuracy of a numerical shell model simulation and its predictive capabilities with existing failure criteria are compared to experiments of a 34 m long blade tested to ultimate failure. Strengths and weaknesses of in-plane failure criteria are highlighted and the geometrical...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    Wind turbine rotor blades are commonly manufactured from composite materials by a moulding process. Typically, the wind turbine blade is produced in two halves, which are eventually adhesively joined along their edges. Investigations of operating wind turbine blades show that debonding of the...... virtual crack closure technique (VCCT) is proposed, which can be used to identify critical areas in the adhesive joint of a trailing edge. The paper gives an overview of methods applicable for fracture cases comprising non-parallel crack faces in the realm of linear fracture mechanics. Furthermore, the...... VCCT is discussed in detail and validated against numerical analyses in 2D and 3D. Finally, the SERR of a typical blade section subjected to various loading conditions is investigated and assessed in order to identify potential design drivers for trailing edge details. Analysis of the blade section...

  10. 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 ...

  11. 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...

  12. 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...

  13. Optimization of the blade trailing edge geometric parameters for a small scale ORC turbine

    International Nuclear Information System (INIS)

    In general, the method proposed by Whitfield and Baines is adopted for the turbine preliminary design. In this design procedure for the turbine blade trailing edge geometry, two assumptions (ideal gas and zero discharge swirl) and two experience values (WR and γ) are used to get the three blade trailing edge geometric parameters: relative exit flow angle β6, the exit tip radius R6t and hub radius R6h for the purpose of maximizing the rotor total-to-static isentropic efficiency. The method above is established based on the experience and results of testing using air as working fluid, so it does not provide a mathematical optimal solution to instruct the optimization of geometry parameters and consider the real gas effects of the organic, working fluid which must be taken into consideration for the ORC turbine design procedure. In this paper, a new preliminary design and optimization method is established for the purpose of reducing the exit kinetic energy loss to improve the turbine efficiency ηts, and the blade trailing edge geometric parameters for a small scale ORC turbine with working fluid R123 are optimized based on this method. The mathematical optimal solution to minimize the exit kinetic energy is deduced, which can be used to design and optimize the exit shroud/hub radius and exit blade angle. And then, the influence of blade trailing edge geometric parameters on turbine efficiency ηts are analysed and the optimal working ranges of these parameters for the equations are recommended in consideration of working fluid R123. This method is used to modify an existing ORC turbine exit kinetic energy loss from 11.7% to 7%, which indicates the effectiveness of the method. However, the internal passage loss increases from 7.9% to 9.4%, so the only way to consider the influence of geometric parameters on internal passage loss is to give the empirical ranges of these parameters, such as the recommended ranges that the value of γ is at 0.3 to 0.4, and the value

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

    DEFF Research Database (Denmark)

    This work investigates how adaptive trailing edge flaps and classical blade pitch can work in concert using a model-based state space control formulation. The trade-off between load reduction and actuator activity is decided by setting different weights in the objective function used by the model......-based controller. The combined control approach allow to achieve higher load alleviations, furthermore, in the presence of e.g. deterioration of an actuator, it enables an online re-tuning of the workload distribution of blade pitch and trailing edge flaps, thus potentially increasing the smart rotor reliability....

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    This work investigates how adaptive trailing edge flaps and classical blade pitch can work in concert using a model-based state space control formulation. The trade-off between load reduction and actuator activity is decided by setting different weights in the objective function used by the model......-based controller. The combined control approach allow to achieve higher load alleviations, furthermore, in the presence of e.g. deterioration of an actuator, it enables an online re-tuning of the workload distribution of blade pitch and trailing edge flaps, thus potentially increasing the smart rotor reliability....

  16. Development of a piezoelectric actuator for trailing-edge flap control of rotor blades

    Science.gov (United States)

    Straub, Friedrich K.; Ngo, Hieu T.; Anand, V.; Domzalski, David B.

    1999-06-01

    Piezoelectric actuator technology has now reached a level where macro-positioning applications in the context of smart structures can be considered. One application with high payoffs is vibration reduction, noise reduction, and performance improvements in helicopters. Integration of piezoelectric actuators in the rotor blade is attractive, since it attacks the problem at the source. The present paper covers the development of a piezoelectric actuator for trailing edge flap control on a 34-foot diameter helicopter main rotor. The design of an actuator using bi-axial stack columns, and its bench, shake, and spin testing are described. A series of enhancements lead to an improved version that, together with use of latest stack technology, meets the requirements. Next steps in this DARPA sponsored program are development of the actuator and full scale rotor system for wind tunnel testing in the NASA Ames 40 X 80 foot wind tunnel and flight testing on the MD Explorer.

  17. Aeroelastic Optimization of a 10 MW Wind Turbine Blade with Active Trailing Edge Flaps

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Tibaldi, Carlo; Zahle, Frederik;

    2016-01-01

    This article presents the aeroelastic optimization of a 10MW wind turbine ‘smart blade’ equipped with active trailing edge flaps. The multi-disciplinary wind turbine analysis and optimization tool HawtOpt2 is utilized, which is based on the open-source framework Open-MDAO. The tool interfaces to...... several state-of-the art simulation codes, allowing for a wide variety of problem formulations and combinations of models. A simultaneous aerodynamic and structural optimization of a 10 MW wind turbine rotor is carried out with respect to material layups and outer shape. Active trailing edge flaps are...

  18. 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.

  19. Heat Transfer in a Complex Trailing Edge Passage for a High Pressure Turbine Blade. Part 2:; Simulation Results

    Science.gov (United States)

    Rigby, David L.; Bunker, Ronald S.

    2002-01-01

    A combined experimental and numerical study to investigate the heat transfer distribution in a complex blade trailing edge passage was conducted. The geometry consists of a two pass serpentine passage with taper toward the trailing edge, as well as from hub to tip. The upflow channel has an average aspect ratio of roughly 14:1, while the exit passage aspect ratio is about 5:1. The upflow channel is split in an interrupted way and is smooth on the trailing edge side of the split and turbulated on the other side. A turning vane is placed near the tip of the upflow channel. Reynolds numbers in the range of 31,000 to 61,000, based on inlet conditions, were simulated numerically. The simulation was performed using the Glenn-HT code, a full three-dimensional Navier-Stokes solver using the Wilcox k-omega turbulence model. A structured multi-block grid is used with approximately 4.5 million cells and average y+ values on the order of unity. Pressure and heat transfer distributions are presented with comparison to the experimental data. While there are some regions with discrepancies, in general the agreement is very good for both pressure and heat transfer.

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

    Science.gov (United States)

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

    1994-01-01

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

  1. Experimental assessment of the aero-thermal performance of rib roughened trailing edge cooling channels for gas turbine blades

    International Nuclear Information System (INIS)

    Based on the combined analysis of detailed flow field and heat transfer experimental data, the aero-thermal behaviour of different trailing edge cooling channels is reported. The reference geometry (G0) is characterized by a trapezoidal cross section of high aspect-ratio, inlet radial flow, and coolant discharge at both model tip and trailing edge, where seven elongated pedestals are also installed. Two variations of the reference geometry have squared ribs installed inside the channel radial central portion (G1) or inside the trailing edge exit region (G2). The forced convection heat transfer coefficient has been measured by means of a steady state Liquid Crystal Thermography (LCT) technique, while reliable and detailed flow measurements have been performed by means of Particle Image Velocimetry (PIV) or Stereo-PIV techniques. The experimental Reynolds number has been fixed at 20,000. The heat transfer data for the three configurations have been analyzed and compared considering both local and channel-averaged features of the heat transfer fields. In particular, the flow mechanisms responsible for the existence of high or low heat transfer regions have been identified and explained. The effects of the different turbulence promoters on both the flow and heat transfer fields have been put in evidence as well. With the aim to determine the most effective configuration, area averaged heat transfer data have been compared, together with information about the channels pressure losses. Configuration G1 turned out to be the most promising, giving rise to a significant heat transfer enhancement associated to a moderate increase in pressure losses. -- Highlights: • Combined aero-thermal analysis of cooling ducts for gas turbine blade trailing edge. • Stereo-PIV and LCT experimental investigation. • Performance comparison of different configurations (smooth and ribbed channels). • Coupling of peculiar flow features with heat transfer augmentation. • Assessment of

  2. Atmospheric Full Scale Testing of a Morphing Trailing Edge Flap System for Wind Turbine Blades

    OpenAIRE

    Barlas, Athanasios; Aagaard Madsen, Helge

    2015-01-01

    A novel Active Flap System (AFS) has been developed at DTU Wind Energy, as a result of a 3-year R&D project following almost 10 years of innovative research in this field. The full scale AFS comprises an active deformable trailing edge has been tested at the unique rotating test facility at the Risø Campus of DTU Wind Energy in Denmark. The design and instrumentation of the wing section and the AFS are described. The general description and objectives of the rotating test rig at the Risø ...

  3. Design of a bidirectional piezoelectric actuator for blade trailing-edge flap

    Science.gov (United States)

    Lee, Taeoh; Chopra, Inderjit

    2001-08-01

    The present research investigates the feasibility of a compact piezoelectric actuator mechanism to oscillate the rotorblade trailing-edge flap for active vibration suppression. The main components of the actuator are two piezostack segments and a dual-stage stroke amplifier. Each piezostack segment is fabricated by bonding five identical piezostacks. A bidirectional double-lever amplification concept is developed, that involves an extended dual-stage lever-fulcrum stroke amplifier and two parallel rows of piezostacks. Both design and fabrication of the trailing-edge flap actuator are addressed. The designed actuator is of size 8-inch length (spanwise), 1.25-inch width (chordwise), 0.75-inch height, and the weight of the prototype is 1.05 lbs. The bench-top test showed 94% of ideal displacement output. To validate the feasibility of the designed actuator, the spin test in the vacuum chamber is planned to evaluate the performance in rotating environment up to 700g of centrifugal loading.

  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. 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...

  6. Active control system for a rotor blade trailing-edge flap

    Science.gov (United States)

    Duvernier, Marc; Reithler, Livier; Guerrero, Jean Y.; Rossi, Rinaldo A.

    2000-06-01

    Reducing the external noise is becoming a major issue for helicopter manufacturers. The idea beyond this goal is to reduce or even avoid the blade vortex interaction (BVI), especially during descent and flights over inhabited areas. This can be achieved by changing locally the lift of the blade. Several strategies to reach this goal are under investigation at EUROCOPTER such as the control of the local incidence of the blade by a direct lift flap. AEROSPATIALE MATRA Corporate Research Centre and AEROSPATIALE MATRA MISSILES proposed an actuator system able to answer EUROCOPTER's needs for moving a direct lift flap. The present paper describes the definition, manufacturing and testing of this new actuator system. This actuator is based on an electromagnetic patented actuation system developed by AEROSPATIALE MATRA MISSILES for missile and aeronautic applications. The particularity of this actuator is its ability to produce the desired force on its whole range of stroke. The flap is designed to be fitted on a DAUPHIN type blade produced by EUROCOPTER and the actuator system was designed to fit the room available within the blade and to produce the right amount of stroke and force within the required frequency range. Other constraints such as centrifugal loading were also taken into account. This paper describes briefly the specifications and the major characteristics of the actuating system and presents some results of its behavior on a representative composite test-bed manufactured by EUROCOPTER when subjected to realistic mechanical loads.

  7. Simulation of Moving Trailing Edge Flaps on a Wind Turbine Blade using a Navier-Stokes based Immersed Boundary Method

    DEFF Research Database (Denmark)

    Behrens, Tim

    trailing edge flap geometries in two and three dimensions. Validation cases were presented for the circular cylinder in a Cartesian mesh topology as well as in a topology similar to a standard body fitted mesh. To simulate trailing edge flaps, a hybrid approach was developed that modeled only the moving...... conforming meshes. A more flexible method would open up an opportunity to investigate the flow features of complex moving flap geometries in great detail. The immersed boundary method offers this flexibility, as the geometry is represented through the introduction of additional forcing terms in the governing...... equations. This approach allows for simulation of arbitrary geometries in fixed meshes that do not need to conform to the body geometry. The flow solver EllipSys has previously been extended with a base implementation of an immersed boundary method. The present work developed the necessary tools to handle...

  8. Trailing edge modifications for flatback airfoils.

    Energy Technology Data Exchange (ETDEWEB)

    Kahn, Daniel L. (University of California, Davis, CA); van Dam, C.P. (University of California, Davis, CA); Berg, Dale E.

    2008-03-01

    The adoption of blunt trailing edge airfoils (also called flatback airfoils) for the inboard region of large wind turbine blades has been proposed. Blunt trailing edge airfoils would not only provide a number of structural benefits, such as increased structural volume and ease of fabrication and handling, but they have also been found to improve the lift characteristics of thick airfoils. Therefore, the incorporation of blunt trailing edge airfoils would allow blade designers to more freely address the structural demands without having to sacrifice aerodynamic performance. These airfoils do have the disadvantage of generating high levels of drag as a result of the low-pressure steady or periodic flow in the near-wake of the blunt trailing edge. Although for rotors, the drag penalty appears secondary to the lift enhancement produced by the blunt trailing edge, high drag levels are of concern in terms of the negative effect on the torque and power generated by the rotor. Hence, devices are sought that mitigate the drag of these airfoils. This report summarizes the literature on bluff body vortex shedding and bluff body drag reduction devices and proposes four devices for further study in the wind tunnel.

  9. Reduction of airfoil trailing edge noise by trailing edge blowing

    International Nuclear Information System (INIS)

    The paper deals with airfoil trailing edge noise and its reduction by trailing edge blowing. A Somers S834 airfoil section which originally was designed for small wind turbines is investigated. To mimic realistic Reynolds numbers the boundary layer is tripped on pressure and suction side. The chordwise position of the blowing slot is varied. The acoustic sources, i.e. the unsteady flow quantities in the turbulent boundary layer in the vicinity of the trailing edge, are quantified for the airfoil without and with trailing edge blowing by means of a large eddy simulation and complementary measurements. Eventually the far field airfoil noise is measured by a two-microphone filtering and correlation and a 40 microphone array technique. Both, LES-prediction and measurements showed that a suitable blowing jet on the airfoil suction side is able to reduce significantly the turbulence intensity and the induced surface pressure fluctuations in the trailing edge region. As a consequence, trailing edge noise associated with a spectral hump around 500 Hz could be reduced by 3 dB. For that a jet velocity of 50% of the free field velocity was sufficient. The most favourable slot position was at 90% chord length

  10. Development of a smart trailing-edge flap actuator with multistage stroke amplifier for a rotor blade

    Science.gov (United States)

    Lee, Taeoh; Chopra, Inderjit

    2000-06-01

    The present research experimentally investigates the feasibility of a trailing-edge flap mechanism actuated in a helicopter rotor by piezoelectric stacks in conjunction with a dual-stage mechanical stroke amplifier to actively control vibration. A new mechanical leverage amplification concept was developed to extend the capability of a simple lever-fulcrum stroke amplifier. A refined prototype actuator and flap mechanism were designed and fabricated using five piezostacks. The bench-top test of the actuator showed 73.7 mils of free stroke and uniform displacement output up to a frequency of 150 Hz. Spin testing was performed in the vacuum chamber to evaluate the performance in rotating environment, and the refined prototype actuator showed approximately 13% loss in actuation stroke at 710 g of full-scale centrifugal loading. In the Open-Jet wind tunnel testing to simulate the aerodynamic loading environment, the peak-to-peak flap deflections above 8 degrees for freestream velocity of 120 ft/sec were obtained at different excitation frequencies. It demonstrated the capability of the refined prototype actuator in rotating environment to potentially reduce helicopter vibration.

  11. Cooled gas turbine blade edge flow analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Marcio Teixeira de [Instituto Tecnologico de Aeronautica, Divisao de Engenharia Mecanica Aeronautica ITA/IEM, Sao Jose dos Campos, SP (Brazil)], e-mail: marcio@ita.br

    2010-07-01

    The flow on the rotating blades of a turbine is unsteady due to the wake of the stator blade row upstream. This unsteadiness is a source of losses and complex flow structures on the rotor blade due to the variation on the turbulence levels and location of the boundary layer laminar to turbulent transition. Convective cooled blades often time have cooling air ejected at the trailing edge right at the blade wake. The present investigation presents an analysis of a canonical flow consistent with the flow topology found at the trailing edge of a gas turbine blade with coolant ejection. A hydrodynamic stability analysis is performed for the combined wake and jet velocity profiles given by a gaussian distribution representing the turbulent rms wake and a laminar jet superposed. The growth rate of any instability found on the flow is an indication of faster mixing, resulting in a reduction on the wake velocity defect and consequently on the complexity associated with it. The results show that increasing the Mach number or the three-dimensionality of the disturbances result in a reduction of the amplification rate. When the flow at the trailing edge is modified by a jet, the amplification rates are lower, but the range of unstable stream wise wavenumbers is larger. (author)

  12. Experimental and numerical investigations of internal heat transfer in an innovative trailing edge blade cooling system: stationary and rotation effects, part 1—experimental results

    Science.gov (United States)

    Beniaiche, Ahmed; Ghenaiet, Adel; Facchini, Bruno

    2016-05-01

    The aero-thermal behavior of the flow field inside 30:1 scaled model reproducing an innovative smooth trailing edge of shaped wedge discharge duct with one row of enlarged pedestals have been investigated in order to determine the effect of rotation, inlet velocity and blowing conditions effects, for Re = 20,000 and 40,000 and Ro = 0-0.23. Two configurations are presented: with and without open tip configurations. Thermo-chromic liquid crystals technique is used to ensure a local measurement of the heat transfer coefficient on the blade suction side under stationary and rotation conditions. Results are reported in terms of detailed 2D HTC maps on the suction side surface as well as the averaged Nusselt number inside the pedestal ducts. Two correlations are proposed, for both closed and open tip configurations, based on the Re, Pr, Ro and a new non-dimensional parameter based on the position along the radial distance, to assess a reliable estimation of the averaged Nusselt number at the inter-pedestal region. A good agreement is found between prediction and experimental data with about ±10 to ±12 % of uncertainty, for the simple form correlation, and about ±16 % using a complex form. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.

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

    Directory of Open Access Journals (Sweden)

    Uğbreve;ur Dalli

    2011-01-01

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

  14. Experimental and numerical investigations of internal heat transfer in an innovative trailing edge blade cooling system: stationary and rotation effects, part 2: numerical results

    Science.gov (United States)

    Beniaiche, Ahmed; Ghenaiet, Adel; Carcasci, Carlo; Facchini, Bruno

    2016-05-01

    This paper presents a numerical validation of the aero-thermal study of a 30:1 scaled model reproducing an innovative trailing edge with one row of enlarged pedestals under stationary and rotating conditions. A CFD analysis was performed by means of commercial ANSYS-Fluent modeling the isothermal air flow and using k-ω SST turbulence model and an isothermal air flow for both static and rotating conditions (Ro up to 0.23). The used numerical model is validated first by comparing the numerical velocity profiles distribution results to those obtained experimentally by means of PIV technique for Re = 20,000 and Ro = 0-0.23. The second validation is based on the comparison of the numerical results of the 2D HTC maps over the heated plate to those of TLC experimental data, for a smooth surface for a Reynolds number = 20,000 and 40,000 and Ro = 0-0.23. Two-tip conditions were considered: open tip and closed tip conditions. Results of the average Nusselt number inside the pedestal ducts region are presented too. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.

  15. Primary control of a Mach scale swashplateless rotor using brushless DC motor actuated trailing edge flaps

    Science.gov (United States)

    Saxena, Anand

    The focus of this research was to demonstrate a four blade rotor trim in forward flight using integrated trailing edge flaps instead of using a swashplate controls. A compact brushless DC motor was evaluated as an on-blade actuator, with the possibility of achieving large trailing edge flap amplitudes. A control strategy to actuate the trailing edge flap at desired frequency and amplitude was developed and large trailing edge flap amplitudes from the motor (instead of rotational motion) were obtained. Once the actuator was tested on the bench-top, a lightweight mechanism was designed to incorporate the motor in the blade and actuate the trailing edge flaps. A six feet diameter, four bladed composite rotor with motor-flap system integrated into the NACA 0012 airfoil section was fabricated. Systematic testing was carried out for a range of load conditions, first in the vacuum chamber followed by hover tests. Large trailing edge flap deflections were observed during the hover testing, and a peak to peak trailing edge flap amplitude of 18 degree was achieved at 2000 rotor RPM with hover tip Mach number of 0.628. A closed loop controller was designed to demonstrate trailing edge flap mean position and the peak to peak amplitude control. Further, a soft pitch link was designed and fabricated, to replace the stiff pitch link and thereby reduce the torsional stiffness of the blade to 2/rev. This soft pitch link allowed for blade root pitch motion in response to the trailing edge flap inputs. Blade pitch response due to both steady as well as sinusoidal flap deflections were demonstrated. Finally, tests were performed in Glenn L. Martin wind tunnel using a model rotor rig to assess the performance of motor-flap system in forward flight. A swashplateless trim using brushless DC motor actuated trailing edge flaps was achieved for a rotor operating at 1200 RPM and an advance ratio of 0.28. Also, preliminary exploration was carried out to test the scalability of the motor

  16. 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

  17. Study of airfoil trailing edge bluntness noise

    DEFF Research Database (Denmark)

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

    This paper deals with airfoil trailing edge noise with special focus on airfoils with blunt trailing edges. Two methods are employed to calculate airfoil noise: The flow/acoustic splitting method and the semi-empirical method. The flow/acoustic splitting method is derived from compressible Navier......-Stokes equations. It provides us possibilities to study details about noise generation mechanism. The formulation of the semi-empirical model is based on acoustic analogy and then curve-fitted with experimental data. Due to its high efficiency, such empirical relation is used for purpose of low noise airfoil...... design or optimization. Calculations from both methods are compared with exist experiments. The airfoil blunt noise is found as a function of trailing edge bluntness, Reynolds number, angle of attack, etc....

  18. 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.

  19. A Noise Reduction Study on Flow-Permeable Trailing-Edges

    OpenAIRE

    Herr, Michaela

    2007-01-01

    This paper summarizes the results of an experimental study on flow-permeable comb-type trailing-edges which have the potential to effectively reduce turbulent boundary-layer trailing-edge noise. Basic design rules are presented with respect to a future use of such devices as suitable add-on solutions for a wide range of technical applications. These are e.g. the high-lift devices of current passenger aircraft, the blades of cooling fans or wind turbines which represent strong trailing-edge no...

  20. Effect of Hydrofoil Trailing Edge Geometry on the Wake Dynamics

    OpenAIRE

    Zobeiri, Amirreza

    2012-01-01

    In the present study, the effect of a hydrofoil trailing edge shape on the wake dynamic and its interaction with the mechanical structure is investigated. This would help better describe the physical reasons for vibration reduction when using oblique and Donaldson trailing edges in comparison to a truncated trailing edge and subsequently allow its further optimization. Thus, hydrofoils with oblique and Donaldson trailing edges are tested in a high-spe...

  1. Numerical Investigation of Flow Control Feasibility with a Trailing Edge Flap

    International Nuclear Information System (INIS)

    This paper concerns a numerical study of employing an adaptive trailing edge flap to control the lift of an airfoil subject to unsteady inflow conditions. The periodically varying inflow is generated by two oscillating airfoils, which are located upstream of the controlled airfoil. To establish the control system, a standard PID controller is implemented in a finite volume based incompressible flow solver. An immersed boundary method is applied to treat the problem of simulating a deformable airfoil trailing edge. The flow field is solved using a 2D Reynolds averaged Navier-Stokes finite volume solver. In order to more accurately simulate wall bounded flows around the immersed boundary, a modified boundary condition is introduced in the k- ω turbulence model. As an example, turbulent flow over a NACA 64418 airfoil with a deformable trailing edge is investigated. Results from numerical simulations are convincing and may give some highlights for practical implementations of trailing edge flap to a wind turbine rotor blade

  2. The Effect of Nozzle Trailing Edge Thickness on Jet Noise

    Science.gov (United States)

    Henderson, Brenda; Kinzie, Kevin; Haskin, Henry

    2004-01-01

    The effect of nozzle trailing edge thickness on broadband acoustic radiation and the production of tones is investigated for coannular nozzles. Experiments were performed for a core nozzle trailing edge thickness between 0.38 mm and 3.17 mm. The on-set of discrete tones was found to be predominantly affected by the velocity ratio, the ratio of the fan velocity to the core velocity, although some dependency on trailing edge thickness was also noted. For a core nozzle trailing edge thickness greater than or equal to 0.89 mm, tones were produced for velocity ratios between 0.91 and 1.61. For a constant nozzle trailing edge thickness, the frequency varied almost linearly with the core velocity. The Strouhal number based on the core velocity changed with nozzle trailing edge thickness and varied between 0.16 and 0.2 for the core nozzles used in the experiments. Increases in broadband noise with increasing trailing edge thickness were observed for tone producing and non-tone producing conditions. A variable thickness trailing edge (crenellated) nozzle resulted in no tonal production and a reduction of the broadband trailing edge noise relative to that of the corresponding constant thickness trailing edge.

  3. Deformable trailing edge flaps for modern megawatt wind turbine controllers using strain gauge sensors

    DEFF Research Database (Denmark)

    Andersen, Peter Bjørn; Henriksen, Lars Christian; Gaunaa, Mac;

    2010-01-01

    enabling the trailing edge to move independently and quickly along the spanwise position of the blade, local small flutuations in the aerodynamic forces can be alleviated by deformation of the airfoil flap. Strain gauges are used as input for the flap controller, and the effect of placing strain gauges at...

  4. Designing Trailing Edge Flaps of Wind Turbines using an Integrated Design Approach

    DEFF Research Database (Denmark)

    Mirzaei, Mahmood; Poulsen, Niels Kjølstad; Niemann, Hans Henrik

    In this paper designing a controller for trailing edge flaps (TEF) as well as optimizing its position on the wind turbine blade will be considered. An integrated design approach will be used to optimize both TEF placement and controller simultaneously. Youla parameterization will be used to...

  5. Aerodynamic Analysis of Trailing Edge Enlarged Wind Turbine Airfoils

    DEFF Research Database (Denmark)

    Xu, Haoran; Shen, Wen Zhong; Zhu, Wei Jun; Yang, Hua; Liu, Chao

    2014-01-01

    The aerodynamic performance of blunt trailing edge airfoils generated from the DU- 91-W2-250, DU-97-W-300 and DU-96-W-350 airfoils by enlarging the thickness of trailing edge symmetrically from the location of maximum thickness to chord to the trailing edge were analyzed by using CFD and RFOIL...... methods at a chord Reynolds number of 3 × 106. The goal of this study is to analyze the aerodynamic performance of blunt trailing edge airfoils with different thicknesses of trailing edge and maximum thicknesses to chord. The steady results calculated by the fully turbulent k-ω SST, transitional k-ω SST...... model and RFOIL all show that with the increase of thickness of trailing edge, the linear region of lift is extended and the maximum lift also increases, the increase rate and amount of lift become limited gradually at low angles of attack, while the drag increases dramatically. For thicker airfoils...

  6. Modeling of Airfoil Trailing Edge Flap with Immersed Boundary Method

    DEFF Research Database (Denmark)

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

    2011-01-01

    The present work considers incompressible flow over a 2D airfoil with a deformable trailing edge. The aerodynamic characteristics of an airfoil with a trailing edge flap is numerically investigated using computational fluid dynamics. A novel hybrid immersed boundary (IB) technique is applied to...... simulate the moving part of the trailing edge. Over the main fixed part of the airfoil the Navier-Stokes (NS) equations are solved using a standard body-fitted finite volume technique whereas the moving trailing edge flap is simulated with the immersed boundary method on a curvilinear mesh. The obtained...

  7. Performance of Swashplateless Ultralight Helicopter Rotor with Trailing-edge Flaps for Primary Flight Control

    Science.gov (United States)

    Shen, Jin-Wei; Chopra, Inderjit

    2003-01-01

    The objective of present study is to evaluate the rotor performance, trailing-edge deflections and actuation requirement of a helicopter rotor with trailing-edge flap system for primary flight control. The swashplateless design is implemented by modifying a two-bladed teetering rotor of an production ultralight helicopter through the use of plain flaps on the blades, and by replacing the pitch link to fixed system control system assembly with a root spring. A comprehensive rotorcraft analysis based on UMARC is carried out to obtain the results for both the swashplateless and a conventional baseline rotor configuration. The predictions show swashplateless configuration achieve superior performance than the conventional rotor attributed from reduction of parasite drag by eliminating swashplate mechanic system. It is indicated that optimal selection of blade pitch index angle, flap location, length, and chord ratio reduces flap deflections and actuation requirements, however, has virtually no effect on rotor performance.

  8. Aeroelastic Stability of a 2D Airfoil Section equipped with a Trailing Edge Flap

    DEFF Research Database (Denmark)

    Bergami, Leonardo

    Recent studies conclude that important reduction of the fatigue loads encountered by a wind turbine blade can be achieved using a deformable trailing edge control system. The focus of the current work is to determine the effect of this flap-like system on the aeroelastic stability of a 2D airfoil...... section. A simulation tool is implemented to predict the flow speed at which a flap equipped section may become unstable, either due to flutter or divergence. First, the stability limits of the airfoil without flap are determined, and, in the second part of the work, a deformable trailing edge flap is...

  9. ANALYSIS OF AN ELECTROSTRICTIVE STACK ACTUATORFOR ACTIVE TRAILING EDGE FLAPS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Helicopter is a complex dynamic system with many rotating components. The rotor blades operate in a highly complex aerodynamic environment. The vibratory hub load, which is caused by cyclic variation of centrifugal and aerodynamic load of the rotating blades in flight, is transmitted to the fuselage, resulting in serious vibration and noise of the structure. It is one of the most important exciting sources in helicopters.  There has long been a desire to reduce helicopter vibration and to improve its performance. Control schemes adopted so far can be classified as either passive or active control technologies. The passive technologies include optimization of rotor hub, blade and the fuselage, hub or blade mounted passive vibration absorbers and anti-resonant vibration isolators. One of the major disadvantages with passive technologies is that they are designed to provide maximum vibration reduction at a specific frequency; therefore, their performance is degraded significantly with changes in the operating conditions of the rotor system.  With the development of computer science and active control technology, increasing efforts have been devoted to active control technologies to benefit helicopter vibration suppression in recent years. Earlier studies include Higher Harmonic Control (HHC)[1] and Individual Blade Control (IBC)[2], which is aimed to reduce the vibratory blade load by oscillating the blade in pitch motion using hydraulic actuators. It is successful in suppressing the vibration of the fuselage; however, its application is limited by serious energy consumption.  To overcome these difficulties, a new concept in helicopter vibration control is the smart rotor system. In this scheme, actuators are embedded in composite blades. They are used to activate the trailing edge flaps in higher harmonic pitch motion to adjust the lift force actively. Under the regulation of a control system, the vibratory hub load can be counteracted actively at

  10. Wind turbine trailing edge aerodynamic brakes

    Energy Technology Data Exchange (ETDEWEB)

    Migliore, P G [National Renewable Energy Lab., Golden, CO (United States); Miller, L S [Wichita State Univ., KS (United States). Dept. of Aerospace Engineering; Quandt, G A

    1995-04-01

    Five trailing-edge devices were investigated to determine their potential as wind-turbine aerodynamic brakes, and for power modulation and load alleviation. Several promising configurations were identified. A new device, called the spoiler-flap, appears to be the best alternative. It is a simple device that is effective at all angles of attack. It is not structurally intrusive, and it has the potential for small actuating loads. It is shown that simultaneous achievement of a low lift/drag ratio and high drag is the determinant of device effectiveness, and that these attributes must persist up to an angle of attack of 45{degree}. It is also argued that aerodynamic brakes must be designed for a wind speed of at least 45 m/s (100 mph).

  11. NUMERICAL AND EXPERIMENTAL INVESTIGATION OF BEVELED TRAILING EDGE FLOW FIELDS

    Institute of Scientific and Technical Information of China (English)

    MOSALLEM M. M.

    2008-01-01

    The characteristics of flow past beveled trailing edges attached to flat plates have been investigated numerically and experimentally. The test models used in the present study were two 2D blunt-faced flat plates having asymmetric beveled trailing edges of angles 27° and 60°. The numerical simulation results display an asymmetric wake behind the 27° beveled trailing edge and von karmen street vortices behind the 60° beveled trailing edge. The flow visualization using cavitation technique showed the same observations of the numerical simulation. Therefore, it is obvious that the trailing edge geometry has a pronounced effect on the wake development and vortex shedding. Also, it is concluded that the cavitation phenomenon can be used as a visualization technique at high flow velocities.

  12. Development of a Wind Turbine Test Rig and Rotor for Trailing Edge Flap Investigation: Static Flap Angles Case

    International Nuclear Information System (INIS)

    One of the strategies used to improve performance and increase the life-span of wind turbines is active flow control. It involves the modification of the aerodynamic characteristics of a wind turbine blade by means of moveable aerodynamic control surfaces. Trailing edge flaps are relatively small moveable control surfaces placed at the trailing edge of a blade's airfoil that modify the lift of a blade or airfoil section. An instrumented wind turbine test rig and rotor were specifically developed to enable a wide-range of experiments to investigate the potential of trailing edge flaps as an active control technique. A modular blade based on the S833 airfoil was designed to allow accurate instrumentation and customizable settings. The blade is 1.7 meters long, had a constant 178mm chord and a 6° pitch. The modular aerodynamic parts were 3D printed using plastic PC-ABS material. The blade design point was within the range of wind velocities in the available large test facility. The wind facility is a large open jet wind tunnel with a maximum velocity of 11m/s in the test area. The capability of the developed system was demonstrated through an initial study of the effect of stationary trailing edge flaps on blade load and performance. The investigation focused on measuring the changes in flapwise bending moment and power production for different trailing edge flap spanwise locations and deflection angles. The relationship between the load reduction and deflection angle was linear as expected from theory and the highest reduction was caused by the flap furthest from the rotor center. Overall, the experimental setup proved to be effective in measuring small changes in flapwise bending moment within the wind turbine blade and will provide insight when (active) flap control is targeted

  13. A Computational Modeling Mystery Involving Airfoil Trailing Edge Treatments

    Science.gov (United States)

    Choo, Yeunun; Epps, Brenden

    2015-11-01

    In a curious result, Fairman (2002) observed that steady RANS calculations predicted larger lift than the experimentally-measured data for six different airfoils with non-traditional trailing edge treatments, whereas the time average of unsteady RANS calculations matched the experiments almost exactly. Are these results reproducible? If so, is the difference between steady and unsteady RANS calculations a numerical artifact, or is there a physical explanation? The goals of this project are to solve this thirteen year old mystery and further to model viscous/load coupling for airfoils with non-traditional trailing edges. These include cupped, beveled, and blunt trailing edges, which are common anti-singing treatments for marine propeller sections. In this talk, we present steady and unsteady RANS calculations (ANSYS Fluent) with careful attention paid to the possible effects of asymmetric unsteady vortex shedding and the modeling of turbulence anisotropy. The effects of non-traditional trailing edge treatments are visualized and explained.

  14. Development of Variable Camber Continuous Trailing Edge Flap System

    Science.gov (United States)

    Urnes, Jim, Sr.; Nguyen, Nhan T.; Dykman, John

    2012-01-01

    This presentation describes the current status of the joint NASA/Boeing collaboration on the development of a variable camber continuous trailing edge flap system for use in wing shaping control for cruise drag reduction.

  15. Improvement of airfoil trailing edge bluntness noise model

    OpenAIRE

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

    2016-01-01

    In this article, airfoil trailing edge bluntness noise is investigated using both computational aero-acoustic and semi-empirical approach. For engineering purposes, one of the most commonly used prediction tools for trailing edge noise are based on semi-empirical approaches, for example, the Brooks, Pope, and Marcolini airfoil noise prediction model developed by Brooks, Pope, and Marcolini (NASA Reference Publication 1218, 1989). It was found in previous study that the Brooks, Pope, and Marco...

  16. Elastically Deformable Side-Edge Link for Trailing-Edge Flap Aeroacoustic Noise Reduction

    Science.gov (United States)

    Khorrami, Mehdi R. (Inventor); Lockard, David P. (Inventor); Moore, James B. (Inventor); Su, Ji (Inventor); Turner, Travis L. (Inventor); Lin, John C. (Inventor); Taminger, Karen M. (Inventor); Kahng, Seun K. (Inventor); Verden, Scott A. (Inventor)

    2014-01-01

    A system is provided for reducing aeroacoustic noise generated by an aircraft having wings equipped with trailing-edge flaps. The system includes a plurality of elastically deformable structures. Each structure is coupled to and along one of the side edges of one of the trailing-edge flaps, and is coupled to a portion of one of the wings that is adjacent to the one of the side edges. The structures elastically deform when the trailing-edge flaps are deployed away from the wings.

  17. Drag reduction of a blunt trailing-edge airfoil

    Science.gov (United States)

    Baker, Jonathon Paul

    Wind-tunnel experimentation and Reynolds-averaged Navier--Stokes simulations were used to analyze simple, static trailing-edge devices applied to an FB-3500-1750 airfoil, a 35% thick airfoil with a 17.5% chord blunt trailing edge, in order to mitigate base drag. The drag reduction devices investigated include Gurney-type tabs, splitter plates, base cavities, and offset cavities. The Gurney-type tabs consisted of small tabs, attached at the trailing edge and distributed along the span, extending above the upper and lower surfaces of the airfoil. The Gurney-type devices were determined to have little drag reduction capabilities for the FB-3500-1750 airfoil. Splitter plates, mounted to the center of the trailing edge, with lengths between 50% and 150% of the trailing-edge thickness and various plate angles (0° and +/-10° from perpendicular) were investigated and shown to influence the lift and drag characteristics of the baseline airfoil. Drag reductions of up to 50% were achieved with the addition of a splitter plate. The base cavity was created by adding two plates perpendicular to the trailing edge, extending from the upper and lower surfaces of the airfoil. The base cavity demonstrated possible drag reductions of 25%, but caused significant changes to lift, primarily due to the method of device implementation. The offset cavity, created by adding two splitter plates offset from the upper and lower surfaces by 25% of the trailing-edge thickness, was shown to improve on the drag reductions of the splitter plate, while also eliminating unsteady vortex shedding prior to airfoil stall.

  18. Effect of Trailing Edge Flow Injection on Fan Noise and Aerodynamic Performance

    Science.gov (United States)

    Fite, E. Brian; Woodward, Richard P.; Podboy, Gary G.

    2006-01-01

    An experimental investigation using trailing edge blowing for reducing fan rotor/guide vane wake interaction noise was completed in the NASA Glenn 9- by 15-foot Low Speed Wind Tunnel. Data were acquired to measure noise, aerodynamic performance, and flow features for a 22" tip diameter fan representative of modern turbofan technology. The fan was designed to use trailing edge blowing to reduce the fan blade wake momentum deficit. The test objective was to quantify noise reductions, measure impacts on fan aerodynamic performance, and document the flow field using hot-film anemometry. Measurements concentrated on approach, cutback, and takeoff rotational speeds as those are the primary conditions of acoustic interest. Data are presented for a 2% (relative to overall fan flow) trailing edge injection rate and show a 2 dB reduction in Overall Sound Power Level (OAPWL) at all fan test speeds. The reduction in broadband noise is nearly constant and is approximately 1.5 dB up to 20 kHz at all fan speeds. Measurements of tone noise show significant variation, as evidenced by reductions of up to 6 dB in the 2 BPF tone at 6700 rpm.: and increases of nearly 2 dB for the 4 BPF tone at approach speed. Aerodynamic performance measurements show the fan with 2 % injection has an overall efficiency that is comparable to the baseline fan and operates, as intended, with nearly the same pressure ratio and mass flow parameters. Hot-film measurements obtained at the approach operating condition indicate that mean blade wake filling in the tip region was not as significant as expected. This suggests that additional acoustic benefits could be realized if the trailing edge blowing could be modified to provide better filling of the wake momentum deficit. Nevertheless, the hot-film measurements indicate that the trailing edge blowing provided significant reductions in blade wake turbulence. Overall, these results indicate that further work may be required to fully understand the proper

  19. Prediction of noise from serrated trailing-edges

    CERN Document Server

    Lyu, B; Sinayoko, S

    2015-01-01

    A new analytical model is developed for the prediction of noise from serrated trailing-edges. The model generalizes Amiet's trailing-edge noise theory to sawtooth trailing-edges, resulting in an inhomogeneous partial differential equation. The equation is then solved by means of a Fourier expansion technique combined with an iterative procedure. The solution is validated through comparison with finite element method for a variety of serrations at different Mach numbers. Results obtained using the new model predict noise reduction of up to 10 dB at 90 degree above the trailing-edge, which is more realistic than predictions based on Howe's model and also more consistent with experimental observations. A thorough analytical and numerical analysis of the physical mechanism is carried out and suggests that the noise reduction due to serration originates primarily from interference effects near the trailing-edge. A closer inspection of the proposed mathematical model has led to the development of two criteria for t...

  20. On the wake flow of asymmetrically beveled trailing edges

    Science.gov (United States)

    Guan, Yaoyi; Pröbsting, Stefan; Stephens, David; Gupta, Abhineet; Morris, Scott C.

    2016-05-01

    Trailing edge and wake flows are of interest for a wide range of applications. Small changes in the design of asymmetrically beveled or semi-rounded trailing edges can result in significant difference in flow features which are relevant for the aerodynamic performance, flow-induced structural vibration and aerodynamically generated sound. The present study describes in detail the flow field characteristics around a family of asymmetrically beveled trailing edges with an enclosed trailing-edge angle of 25° and variable radius of curvature R. The flow fields over the beveled trailing edges are described using data obtained by particle image velocimetry (PIV) experiments. The flow topology for different trailing edges was found to be strongly dependent on the radius of curvature R, with flow separation occurring further downstream as R increases. This variation in the location of flow separation influences the aerodynamic force coefficients, which were evaluated from the PIV data using a control volume approach. Two-point correlations of the in-plane velocity components are considered to assess the structure in the flow field. The analysis shows large-scale coherent motions in the far wake, which are associated with vortex shedding. The wake thickness parameter yf is confirmed as an appropriate length scale to characterize this large-scale roll-up motion in the wake. The development in the very near wake was found to be critically dependent on R. In addition, high-speed PIV measurements provide insight into the spectral characteristics of the turbulent fluctuations. Based on the time-resolved flow field data, the frequency range associated with the shedding of coherent vortex pairs in the wake is identified. By means of time-correlation of the velocity components, turbulent structures are found to convect from the attached or separated shear layers without distinct separation point into the wake.

  1. Design and performance prediction of swashplateless helicopter rotors with trailing edge flaps and tabs

    Science.gov (United States)

    Falls, Jaye

    This work studies the design of trailing edge controls for swashplateless helicopter primary control, and examines the impact of those controls on the performance of the rotor. The objective is to develop a comprehensive aeroelastic analysis for swashplateless rotors in steady level flight. The two key issues to be solved for this swashplateless control concept are actuation of the trailing edge controls and evaluating the performance of the swashplateless rotor compared to conventionally controlled helicopters. Solving the first requires simultaneous minimization of trailing flap control angles and hinge moments to reduce actuation power. The second issue requires not only the accurate assessment of swashplateless rotor power, but also similar or improved performance compared to conventional rotors. The analysis consists of two major parts, the structural model and the aerodynamic model. The inertial contributions of the trailing edge flap and tab are derived and added to the system equations in the structural model. Two different aerodynamic models are used in the analysis, a quasi-steady thin airfoil theory that includes arbitrary hinge positions for the flap and the tab, and an unsteady lifting line model with airfoil table lookup based on wind tunnel test data and computational fluid dynamics simulation. The design aspect of the problem is investigated through parametric studies of the trailing edge flap and tab for a Kaman-type conceptual rotor and a UH-60A swashplateless variant. The UH-60A model is not changed except for the addition of a trailing edge flap to the rotor blade, and the reduction of pitch link stiffness to imitate a soft root spring. Study of the uncoupled blade response identifies torsional stiffness and flap hinge stiffness as important design features of the swashplateless rotor. Important trailing edge flap and tab design features including index angle, aerodynamic overhang, chord and length are identified through examination of coupled

  2. Trailing edge noise model applied to wind turbine airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Bertagnolio, F.

    2008-01-15

    The aim of this work is firstly to provide a quick introduction to the theory of noise generation that are relevant to wind turbine technology with focus on trailing edge noise. Secondly, the socalled TNO trailing edge noise model developed by Parchen [1] is described in more details. The model is tested and validated by comparing with other results from the literature. Finally, this model is used in the optimization process of two reference airfoils in order to reduce their noise signature: the RISOE-B1-18 and the S809 airfoils. (au)

  3. Trailing edge noise model applied to wind turbine airfoils

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    The aim of this work is firstly to provide a quick introduction to the theory of noise generation that are relevant to wind turbine technology with focus on trailing edge noise. Secondly, the socalled TNO trailing edge noise model developed by Parchen [1] is described in more details. The model i...... tested and validated by comparing with other results from the literature. Finally, this model is used in the optimization process of two reference airfoils in order to reduce their noise signature: the RISØ-B1-18 and the S809 airfoils....

  4. A dynamic stall model for airfoils with deformable trailing edges

    DEFF Research Database (Denmark)

    Andersen, Peter Bjørn; Gaunaa, Mac; Bak, Christian; Hansen, Morten Hartvig

    2009-01-01

    The present work contains an extension of the Beddoes-Leishman-type dynamic stall model. In this work, a deformable trailing-edge flap has been added to the dynamic stall model. The model predicts the unsteady aerodynamic forces and moments on an airfoil section undergoing arbitrary motion in heave......, lead-lag, pitch, trailing-edge flapping. In the linear region, the model reduces to the inviscid model, which includes the aerodynamic effect of a thin airfoil with a deformable camberline in inviscid flow. Therefore, the proposed model can be considered a crossover between the work of Gaunaa for the...

  5. Improvement of airfoil trailing edge bluntness noise model

    DEFF Research Database (Denmark)

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

    2016-01-01

    In this article, airfoil trailing edge bluntness noise is investigated using both computational aero-acoustic and semi-empirical approach. For engineering purposes, one of the most commonly used prediction tools for trailing edge noise are based on semi-empirical approaches, for example, the Brooks......, Pope, and Marcolini airfoil noise prediction model developed by Brooks, Pope, and Marcolini (NASA Reference Publication 1218, 1989). It was found in previous study that the Brooks, Pope, and Marcolini model tends to over-predict noise at high frequencies. Furthermore, it was observed that this was...

  6. A dynamic stall model for airfoils with deformable trailing edges

    DEFF Research Database (Denmark)

    Andersen, Peter Bjørn; Gaunaa, Mac; Bak, Dan Christian; Hansen, Morten Hartvig

    2007-01-01

    airfoil section undergoing arbitrary motion in heave, lead-lag, pitch, Trailing Edge (TE) flapping. In the linear region, the model reduces to the inviscid model of Gaunaa [4], which includes the aerodynamic effect of a thin airfoil with a deformable camberline in inviscid flow. Therefore, the proposed......The present work contains an extension of the Beddoes-Leishman (B-L) type dynamic stall model, as described by Hansen et al. [7]. In this work a Deformable Trailing Edge Geometry (DTEG) has been added to the dynamic stall model. The model predicts the unsteady aerodynamic forces and moments on an...

  7. Design, manufacturing and testing of Controllable Rubber Trailing Edge Flaps

    DEFF Research Database (Denmark)

    Løgstrup Andersen, Tom; Aagaard Madsen, Helge; Barlas, Thanasis K;

    The overall goal for the INDUFLAP project was realization of a test facility for development and test of Controllable Rubber Trailing Edge Flaps (CRTEF) for wind turbines. This report covers experimental work at DTU Wind Energy including design, manufacture and test of different configurations of...

  8. Aeroelastic Stability of a 2D Airfoil Section equipped with a Trailing Edge Flap

    OpenAIRE

    Bergami, Leonardo

    2008-01-01

    Recent studies conclude that important reduction of the fatigue loads encountered by a wind turbine blade can be achieved using a deformable trailing edge control system. The focus of the current work is to determine the effect of this flap-like system on the aeroelastic stability of a 2D airfoil section. A simulation tool is implemented to predict the flow speed at which a flap equipped section may become unstable, either due to flutter or divergence. First, the stability limits of the airfo...

  9. Continuous Trailing-Edge Flaps for Primary Flight Control of a Helicopter Main Rotor

    Science.gov (United States)

    Thornburgh, Robert P.; Kreshock, Andrew R.; Wilbur, Matthew L.; Sekula, Martin K.; Shen, Jinwei

    2014-01-01

    The use of continuous trailing-edge flaps (CTEFs) for primary flight control of a helicopter main rotor is studied. A practical, optimized bimorph design with Macro-Fiber Composite actuators is developed for CTEF control, and a coupled structures and computational fluid dynamics methodology is used to study the fundamental behavior of an airfoil with CTEFs. These results are used within a comprehensive rotorcraft analysis model to study the control authority requirements of the CTEFs when utilized for primary flight control of a utility class helicopter. A study of the effect of blade root pitch index (RPI) on CTEF control authority is conducted, and the impact of structural and aerodynamic model complexity on the comprehensive analysis results is presented. The results show that primary flight control using CTEFs is promising; however, a more viable option may include the control of blade RPI, as well.

  10. 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...

  11. Measurement and Scaling of Trailing-Edge Noise

    OpenAIRE

    Herr, Michaela

    2009-01-01

    The presentation provides an overview on DLR’s research activity in trailing-edge (TE) noise source description. Current efforts aim at establish-ing the necessary data quality required for CAA validation. The specific challenges with regard to farfield TE noise measurements in open-jet wind-tunnels are pinpointed for the example of elliptic mirror measurements in the Acoustic Wind Tunnel Braunschweig (AWB) the results of which are compared to corresponding free-field microphone data. Th...

  12. Optimal placement of trailing-edge flaps for helicopter vibration reduction using response surface methods

    Science.gov (United States)

    Viswamurthy, S. R.; Ganguli, Ranjan

    2007-03-01

    This study aims to determine optimal locations of dual trailing-edge flaps to achieve minimum hub vibration levels in a helicopter, while incurring low penalty in terms of required trailing-edge flap control power. An aeroelastic analysis based on finite elements in space and time is used in conjunction with an optimal control algorithm to determine the flap time history for vibration minimization. The reduced hub vibration levels and required flap control power (due to flap motion) are the two objectives considered in this study and the flap locations along the blade are the design variables. It is found that second order polynomial response surfaces based on the central composite design of the theory of design of experiments describe both objectives adequately. Numerical studies for a four-bladed hingeless rotor show that both objectives are more sensitive to outboard flap location compared to the inboard flap location by an order of magnitude. Optimization results show a disjoint Pareto surface between the two objectives. Two interesting design points are obtained. The first design gives 77 percent vibration reduction from baseline conditions (no flap motion) with a 7 percent increase in flap power compared to the initial design. The second design yields 70 percent reduction in hub vibration with a 27 percent reduction in flap power from the initial design.

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

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Poulsen, Niels Kjølstad

    2015-01-01

    The paper proposes a smart rotor configuration where adaptive trailing edge flaps (ATEFs) are employed for active alleviation of the aerodynamic loads on the blades of the NREL 5 MW reference turbine. The flaps extend for 20% of the blade length and are controlled by a linear quadratic (LQ...... effects of active flap control are assessed with aeroelastic simulations of the turbine in normal operation conditions, as prescribed by the International Electrotechnical Commission standard. The turbine lifetime fatigue damage equivalent loads provide a convenient summary of the results achieved with...

  14. Aeroservoelastic stability of a 2D airfoil section equipped with a trailing edge flap

    Energy Technology Data Exchange (ETDEWEB)

    Bergami, Leonardo

    2008-11-15

    Recent studies conclude that important reduction of the fatigue loads encountered by a wind turbine blade can be achieved using a deformable trailing edge control system. The focus of the current work is to determine the effect of this flap-like system on the aeroelastic stability of a 2D airfoil section. A simulation tool is implemented to predict the flow speed at which a flap equipped section may become unstable, either due to flutter or divergence. First, the stability limits of the airfoil without flap are determined, and, in the second part of the work, a deformable trailing edge flap is applied. Stability is investigated for the uncontrolled flap, and for three different control algorithms. The three controls are tuned for fatigue load alleviation and they are based on, respectively, measurement of the heave displacement and velocity, measurement of the local angle of attack, measurement of the pressure difference between the two sides of the airfoil. The stability of the aeroservoelastic system in a defined equilibrium state, and for a given flow speed, is then determined by solving an eigenvalue problem. Results show that the trailing edge control system modifies significantly the stability limits of the section. In the investigated case, increased flutter limits are reported when the elastic flap is left without control, whereas, by applying any of the control algorithms, the flutter velocity is reduced. Nevertheless, only in the heave control case the flutter limit becomes critically close to normal operation flow speeds. Furthermore, a marked dependence of the stability limits on the control gain is also observed and, by tuning the gain parameters, flutter and divergence can be suppressed for flow speed even above the flutter velocity encountered with uncontrolled flap. (author)

  15. Numerical analysis of linear buckling of wind turbine blade with different trailing bonding models

    Science.gov (United States)

    Zhang, J. D.; Xu, Y.

    2013-12-01

    The work focus on the linear buckling analysis of wind turbine blade with different trailing bonding models. Based on finite element model, it has been demonstrated that there are some differences for buckling load factor between different models. Several different models are valid for buckling analysis.

  16. Static Extended Trailing Edge for Lift Enhancement: Experimental and Computational Studies

    Science.gov (United States)

    Liu, Tianshu; Montefort; Liou, William W.; Pantula, Srinivasa R.; Shams, Qamar A.

    2007-01-01

    A static extended trailing edge attached to a NACA0012 airfoil section is studied for achieving lift enhancement at a small drag penalty. It is indicated that the thin extended trailing edge can enhance the lift while the zero-lift drag is not significantly increased. Experiments and calculations are conducted to compare the aerodynamic characteristics of the extended trailing edge with those of Gurney flap and conventional flap. The extended trailing edge, as a simple mechanical device added on a wing without altering the basic configuration, has a good potential to improve the cruise flight efficiency.

  17. Design of piezostack-driven trailing-edge flap actuator for helicopter rotors

    Science.gov (United States)

    Lee, Taeoh; Chopra, Inderjit

    2001-02-01

    A piezoelectric actuator is investigated to activate a trailing-edge flap mechanism for helicopter vibration suppression. This paper presents the development of a piezostack-based actuator with a new stroke amplification mechanism. A double-lever amplification concept is introduced, which is a dual-stage lever-fulcrum stroke amplifier that extends the capability of the conventional lever-fulcrum mechanism. Both the design and fabrication of the on-blade trailing-edge flap actuator are addressed. The first prototype actuator was designed and fabricated using two piezostack segments. An amplification factor of 19.4 and constant response covering up to 8/rev (52.3 Hz) were measured under non-rotating conditions, and a consistent actuator displacement of up to 600g of centrifugal loading was experimentally obtained for the vacuum spin testing. A major design refinement resulted in the second prototype actuator that uses five piezostack segments. The bench-top testing of the second prototype actuator showed 1.87 mm (73.7 mil) of free stroke, and uniform performance of up to 150 Hz. In vacuum spin testing, the second prototype actuator showed approximately 13% loss in actuation stroke at 700g of centrifugal loading, and no further degradation at 115% overloading condition. The double-lever amplification mechanism with piezostack actuation showed the potential for operation in a rotating environment.

  18. Testing of a new morphing trailing edge flap system on a novel outdoor rotating test rig

    DEFF Research Database (Denmark)

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

    2015-01-01

    The morphing trailing edge system or flap system, CRTEF, has been developed over the last 10 years at DTU Wind Energy. After a promising wind tunnel test of the system in 2009 the INDUFLAP project has been carried out from 2011-2014 to transfer the technology from laboratory to industrial...... manufacturing and application. To narrow the gap between wind tunnel testing and full scale prototype testing we developed the rotating test rig. The overall objectives with the rotating test rig are: 1) to test the flap system in a realistic rotating environment with a realistic g-loading; 2) to measure the...... flap performance in real turbulent inflow and 3) to test the flap system in a realistic size and Reynolds number when comparing with full scale applications.. The rotating test rig consists of a 2.2m blade section attached to a 10m boom and mounted on a 100kW turbine platform. It was installed in June...

  19. Swashplateless Helicopter Experimental Investigation: Primary Control with Trailing Edge Flaps Actuated with Piezobenders

    Science.gov (United States)

    Copp, Peter

    Helicopter rotor primary control is conventionally carried out using a swashplate with pitch links. Eliminating the swashplate promises to reduce the helicopter's parasitic power in high speed forward flight, as well as may lead to a hydraulic-less vehicle. A Mach-scale swashplateless rotor is designed with integrated piezobender-actuated trailing edge flaps and systematically tested on the benchtop, in the vacuum chamber and on the hoverstand. The blade is nominally based on the UH-60 rotor with a hover tip Mach number of 0.64. The blade diameter is 66 inches requiring 2400 RPM for Mach scale simulation. The rotor hub is modified to reduce the blade fundamental torsional frequency to less than 2.0/rev by replacing the rigid pitch links with linear springs, which results in an increase of the blade pitching response to the trailing edge flaps. Piezoelectric multilayer benders provide the necessary bandwidth, stroke and stiffness to drive the flaps for primary control while fitting inside the blade profile and withstanding the high centrifugal forces. This work focuses on several key issues. A piezobender designed from a soft piezoelectric material, PZT-5K4, is constructed. The new material is used to construct multi-layer benders with increased stroke for the same stiffness relative to hard materials such as PZT-5H2. Each layer has a thickness of 10 mils. The soft material with gold electrodes requires a different bonding method than hard material with nickel electrodes. With this new bonding method, the measured stiffness matches precisely the predicted stiffness for a 12 layer bender with 1.26 inch length and 1.0 inch width with a stiffness of 1.04 lb/mil. The final in-blade bender has a length of 1.38 inches and 1.0 inch width with a stiffness of 0.325 lb/mil and stroke of 20.2 mils for an energy output of 66.3 lb-mil. The behavior of piezobenders under very high electric fields is investigated. High field means +18.9 kV/cm (limited by arcing in air) and -3.54k

  20. Adjoint-based optimization of flapping plates hinged with a trailing-edge flap

    Directory of Open Access Journals (Sweden)

    Min Xu

    2015-01-01

    Full Text Available It is important to understand the impact of wing-morphing on aerodynamic performance in the study of flapping-wing flight of birds and insects. We use a flapping plate hinged with a trailing-edge flap as a simplified model for flexible/morphing wings in hovering. The trailing-edge flapping motion is optimized by an adjoint-based approach. The optimized configuration suggests that the trailing-edge flap can substantially enhance the overall lift. Further analysis indicates that the lift enhancement by the trailing-edge flapping is from the change of circulation in two ways: the local circulation change by the rotational motion of the flap, and the modification of vortex shedding process by the relative location between the trailing-edge flap and leading-edge main plate.

  1. Experimental and simulated control of lift using trailing edge devices

    International Nuclear Information System (INIS)

    Two active aerodynamic load control (AALC) devices coupled with a control algorithm are shown to decrease the change in lift force experienced by an airfoil during a change in freestream velocity. Microtabs are small (1% chord) surfaces deployed perpendicular to an airfoil, while microjets are pneumatic jets with flow perpendicular to the surface of the airfoil near the trailing edge. Both devices are capable of producing a rapid change in an airfoil's lift coefficient. A control algorithm for microtabs has been tested in a wind tunnel using a modified S819 airfoil, and a microjet control algorithm has been simulated for a NACA 0012 airfoil using OVERFLOW. In both cases, the AALC devices have shown the ability to mitigate the changes in lift during a gust

  2. Trailing Edge Noise Model Validation and Application to Airfoil Optimization

    DEFF Research Database (Denmark)

    Bertagnolio, Franck; Aagaard Madsen, Helge; Bak, Christian

    2010-01-01

    The aim of this article is twofold. First, an existing trailing edge noise model is validated by comparing with airfoil surface pressure fluctuations and far field sound pressure levels measured in three different experiments. The agreement is satisfactory in one case but poor in two other cases....... Nevertheless, the model reproduces the main tendencies observed in the measurements with respect to varying flow conditions. Second, the model is implemented into an airfoil design code that is originally used for aerodynamic optimization. An existing wind turbine airfoil is optimized in order to reduce its...... noise emission, trying at the same time to preserve some of its aerodynamic and geometric characteristics. The new designs are characterized by less cambered airfoils and flatter suction sides. The resulting noise reductions seem to be mainly achieved by a reduction in the turbulent kinetic energy...

  3. Numerical simulation of airfoil trailing edge serration noise

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong

    In the present work, numerical simulations are carried out for a low noise airfoil with and without serrated Trailing Edge. The Ffowcs Williams-Hawkings acoustic analogy is implemented into the in-house incompressible flow solver EllipSys3D. The instantaneous hydrodynamic pressure and velocity...... field are obtained using Large Eddy Simulation. To obtain the time history data of sound pressure, the flow quantities are integrated around the airfoil surface through the FW-H approach. The extended length of the serration is about 16.7% of the airfoil chord and the geometric angle of the serration is...... 28 degrees. The chord based Reynolds number is around 1.5x106. Simulations are compared with existing wind tunnel experiments at various angles of attack. Even though the airfoil under investigation is already optimized for low noise emission, numerical simulations and wind tunnel experiments show...

  4. Atmospheric testing of wind turbine trailing edge aerodynamic brakes

    Energy Technology Data Exchange (ETDEWEB)

    Miller, L.S. [Wichita State Univ., KS (United States); Migliore, P.G. [National Renewable Energy Lab., Golden, CO (United States); Quandt, G.A.

    1997-12-31

    An experimental investigation was conducted using an instrumented horizontal-axis wind turbine that incorporated variable span trailing-edge aerodynamic brakes. A primary goal was to directly compare study results with (infinite-span) wind tunnel data and to provide information on how to account for device span effects during turbine design or analysis. Comprehensive measurements were utilized to define effective changes in the aerodynamic coefficients, as a function of angle of attack and control deflection, for three device spans and configurations. Differences in the lift and drag behavior are most pronounced near stall and for device spans of less than 15%. Drag performance is affected only minimally (<70%) for 15% or larger span devices. Interestingly, aerodynamic controls with characteristic vents or openings appear most affected by span reductions and three-dimensional flow.

  5. 2D numerical comparison of trailing edge flaps - UpWind WP1B3

    DEFF Research Database (Denmark)

    Buhl, Thomas; Andersen, Peter Bjørn; Barlas, T.K.

    This report covers the investigations and comparisons of trailing edge flaps carried out by Delft and Risø. The work is a part of the W1B3 work package of the UpWind EU-project. This report covers only 2D test cases with simple control of the trailing edge flap with the objective of keeping CL...

  6. Heat Transfer and Friction Studies in a Tilted and Rib-Roughened Trailing-Edge Cooling Cavity with and without the Trailing-Edge Cooling Holes

    Directory of Open Access Journals (Sweden)

    M. E. Taslim

    2014-01-01

    Full Text Available Local and average heat transfer coefficients and friction factors were measured in a test section simulating the trailing-edge cooling cavity of a turbine airfoil. The test rig with a trapezoidal cross-sectional area was rib-roughened on two opposite sides of the trapezoid (airfoil pressure and suction sides with tapered ribs to conform to the cooling cavity shape and had a 22-degree tilt in the flow direction upstream of the ribs that affected the heat transfer coefficients on the two rib-roughened surfaces. The radial cooling flow traveled from the airfoil root to the tip while exiting through 22 cooling holes along the airfoil trailing-edge. Two rib geometries, with and without the presence of the trailing-edge cooling holes, were examined. The numerical model contained the entire trailing-edge channel, ribs, and trailing-edge cooling holes to simulate exactly the tested geometry. A pressure-correction based, multiblock, multigrid, unstructured/adaptive commercial software was used in this investigation. Realizable k-ε turbulence model in conjunction with enhanced wall treatment approach for the near wall regions was used for turbulence closure. The applied thermal boundary conditions to the CFD models matched the test boundary conditions. Comparisons are made between the experimental and numerical results.

  7. Coherent structures in trailing-edge cooling and the challenge for turbulent heat transfer modelling

    International Nuclear Information System (INIS)

    Highlights: • Standard RANS model for predicting heat transfer is tested for turbine trailing-edge cooling. • High-fidelity LES as reference data and validation against experiments for different conditions. • LES replicated experimentally observed counter-intuitive decrease of cooling effectiveness. • RANS failed in predicting this behaviour and yielded too high cooling effectiveness. • Standard RANS model cannot predict turbulent heat fluxes caused by large coherent structures. - Abstract: The present paper tests the capability of a standard Reynolds-Averaged Navier–Stokes (RANS) turbulence model for predicting the turbulent heat transfer in a generic trailing-edge situation with a cutback on the pressure side of the blade. The model investigated uses a gradient-diffusion assumption with a scalar turbulent-diffusivity and constant turbulent Prandtl number. High-fidelity Large-Eddy Simulations (LES) were performed for three blowing ratios to provide reliable target data and the mean velocity and eddy viscosity as input for the heat transfer model testing. Reasonably good agreement between the LES and recent experiments was achieved for mean flow and turbulence statistics. The LES yielded coherent structures which were analysed, in particular with respect to their effect on the turbulent heat transfer. For increasing blowing ratio, the LES replicated an also experimentally observed counter-intuitive decrease of the cooling effectiveness caused by the coherent structures becoming stronger. In contrast, the RANS turbulent heat transfer model failed in predicting this behaviour and yielded significantly too high cooling effectiveness. It is shown that the model cannot predict the strong upstream and wall-directed turbulent heat fluxes caused by large coherent structures, which were found to be responsible for the counter-intuitive decrease of the cooling effectiveness

  8. Trailing edge devices to improve performance and increase lifetime of wind-electric water pumping systems

    Energy Technology Data Exchange (ETDEWEB)

    Vick, B.D.; Clark, R.N. [USDA-Agricultural Research Service, Bushland, TX (United States)

    1996-12-31

    Trailing edge flaps were applied to the blades of a 10 kW wind turbine used for water pumping to try to improve the performance and decrease the structural fatigue on the wind turbine. Most small wind turbines (10 kW and below) use furling (rotor turns out of wind similar to a mechanical windmill) to protect the wind turbine from overspeed during high winds. Some small wind turbines, however, do not furl soon enough to keep the wind turbine from being off line part of the time in moderately high wind speeds (10 - 16 m/s). As a result, the load is disconnected and no water is pumped at moderately high wind speeds. When the turbine is offline, the frequency increases rapidly often causing excessive vibration of the wind turbine and tower components. The furling wind speed could possibly be decreased by increasing the offset between the tower centerline and the rotor centerline, but would be a major and potentially expensive retrofit. Trailing edge flaps (TEF) were used as a quick inexpensive method to try to reduce the furling wind speed and increase the on time by reducing the rotor RPM. One TEF configuration improved the water pumping performance at moderately high wind speeds, but degraded the pumping performance at low wind speeds which resulted in little change in daily water volume. The other TEF configuration differed very little from the no flap configuration. Both TEF configurations however, reduced the rotor RPM in high wind conditions. The TEF, did not reduce the rotor RPM by lowering the furling wind speed as hoped, but apparently did so by increasing the drag which also reduced the volume of water pumped at the lower wind speeds. 6 refs., 9 figs.

  9. Atmospheric tests of trailing-edge aerodynamic devices

    Energy Technology Data Exchange (ETDEWEB)

    Miller, L S; Huang, S [Wichita State Univ., KS (United States); Quandt, G A

    1998-01-01

    An experiment was conducted at the National Renewable Energy Laboratory`s (NREL`s) National Wind Technology Center (NWTC) using an instrumented horizontal-axis wind turbine that incorporated variable-span, trailing-edge aerodynamic brakes. The goal of the investigation was to directly compare results with (infinite-span) wind tunnel data and to provide information on how to account for device span effects during turbine design or analysis. Comprehensive measurements were used to define effective changes in the aerodynamic and hinge-moment coefficients, as a function of angle of attack and control deflection, for three device spans (7.5%, 15%, and 22.5%) and configurations (Spoiler-Flap, vented sileron, and unvented aileron). Differences in the lift and drag behavior are most pronounced near stall and for device spans of less than 15%. Drag performance is affected only minimally (about a 30% reduction from infinite-span) for 15% or larger span devices. Interestingly, aerodynamic controls with vents or openings appear most affected by span reductions and three-dimensional flow.

  10. Aerodynamic Characteristic of the Active Compliant Trailing Edge Concept

    Science.gov (United States)

    Nie, Rui; Qiu, Jinhao; Ji, Hongli; Li, Dawei

    2016-06-01

    This paper introduces a novel Morphing Wing structure known as the Active Compliant Trailing Edge (ACTE). ACTE structures are designed using the concept of “distributed compliance” and wing skins of ACTE are fabricated from high-strength fiberglass composites laminates. Through the relative sliding between upper and lower wing skins which are connected by a linear guide pairs, the wing is able to achieve a large continuous deformation. In order to present an investigation about aerodynamics and noise characteristics of ACTE, a series of 2D airfoil analyses are established. The aerodynamic characteristics between ACTE and conventional deflection airfoil are analyzed and compared, and the impacts of different ACTE structure design parameters on aerodynamic characteristics are discussed. The airfoils mentioned above include two types (NACA0012 and NACA64A005.92). The computing results demonstrate that: compared with the conventional plane flap airfoil, the morphing wing using ACTE structures has the capability to improve aerodynamic characteristic and flow separation characteristic. In order to study the noise level of ACTE, flow field analysis using LES model is done to provide noise source data, and then the FW-H method is used to get the far field noise levels. The simulation results show that: compared with the conventional flap/aileron airfoil, the ACTE configuration is better to suppress the flow separation and lower the overall sound pressure level.

  11. Adaptive trailing edge flaps for active load alleviation in a smart rotor configuration

    Energy Technology Data Exchange (ETDEWEB)

    Bergami, L.

    2013-08-15

    The work investigates the development of an active smart rotor concept from an aero-servo-elastic perspective. An active smart rotor is a wind turbine rotor that, through a combination of sensors, control units and actuators, is able to alleviate the fluctuating part of the aerodynamic loads it has to withstand. The investigation focuses on a specific actuator type: the Adaptive Trailing Edge Flap (ATEF), which introduces a continuous deformation of the aft part of the airfoil camber-line. An aerodynamic model that accounts for the steady and unsteady effects of the flap deflection on a 2D airfoil section is developed, and, considering both attached and separated flow conditions, is validated by comparison against Computational Fluid Dynamic solutions and a panel code method. The aerodynamic model is integrated in the BEM-based aeroelastic simulation code HAWC2, thus providing a tool able to simulate the response of a wind turbine equipped with ATEF. A load analysis of the NREL 5 MW reference turbine in its baseline configuration reveals that the highest contribution to the blade flapwise fatigue damage originates from normal operation above rated wind speed, and from loads characterized by frequencies below 1 Hz. The analysis also reports that periodic load variations on the turbine blade account for nearly 11 % of the blade flapwise lifetime fatigue damage, while the rest is ascribed to load variations from disturbances of stochastic nature. The study proposes a smart rotor configuration with flaps laid out on the outer 20 % of the blade span, from 77 % to 97% of the blade length. The configuration is first tested with a simplified cyclic control approach, which gives a preliminary indication of the load alleviation potential, and also reveals the possibility to enhance the rotor energy capture below rated conditions by using the flaps. Two model based control algorithms are developed to actively alleviate the fatigue loads on the smart rotor with ATEF. The first

  12. The Prediction of Noise Due to Jet Turbulence Convecting Past Flight Vehicle Trailing Edges

    Science.gov (United States)

    Miller, Steven A. E.

    2014-01-01

    High intensity acoustic radiation occurs when turbulence convects past airframe trailing edges. A mathematical model is developed to predict this acoustic radiation. The model is dependent on the local flow and turbulent statistics above the trailing edge of the flight vehicle airframe. These quantities are dependent on the jet and flight vehicle Mach numbers and jet temperature. A term in the model approximates the turbulent statistics of single-stream heated jet flows and is developed based upon measurement. The developed model is valid for a wide range of jet Mach numbers, jet temperature ratios, and flight vehicle Mach numbers. The model predicts traditional trailing edge noise if the jet is not interacting with the airframe. Predictions of mean-flow quantities and the cross-spectrum of static pressure near the airframe trailing edge are compared with measurement. Finally, predictions of acoustic intensity are compared with measurement and the model is shown to accurately capture the phenomenon.

  13. Trailing edges projected to move faster than leading edges for large pelagic fish habitats under climate change

    Science.gov (United States)

    Robinson, L. M.; Hobday, A. J.; Possingham, H. P.; Richardson, A. J.

    2015-03-01

    There is mounting evidence to suggest that many species are shifting their ranges in concordance with the climate velocity of their preferred environmental conditions/habitat. While accelerated rates in species' range shifts have been noted in areas of intense warming, due to climate change, few studies have considered the influence that both spatial temperature gradients and rates of warming (i.e., the two components of climate velocity) could have on rates of movement in species habitats. We compared projected shifts in the core habitat of nine large pelagic fish species (five tuna, two billfish and two shark species) off the east coast of Australia at different spatial points (centre, leading and trailing edges of the core habitat), during different seasons (summer and winter), in the near-(2030) and long-term (2070), using independent species distribution models and habitat suitability models. Model projections incorporated depth integrated temperature data from 11 climate models with a focus on the IPCC SRES A2 general emission scenario. Projections showed a number of consistent patterns: southern (poleward) shifts in all species' core habitats; trailing edges shifted faster than leading edges; shifts were faster by 2070 than 2030; and there was little difference in shifts among species and between seasons. Averaging across all species and climate models, rates of habitat shifts for 2030 were 45-60 km decade-1 at the trailing edge, 40-45 km decade-1 at the centre, and 20-30 km decade-1 at the leading edge. Habitat shifts for 2070 were 60-70 km decade-1 at the trailing edge, 50-55 km decade-1 at the centre, and 30-40 km decade-1 at the leading edge. It is often assumed that the leading edge of a species range will shift faster than the trailing edge, but there are few projections or observations in large pelagic fish to validate this assumption. We found that projected shifts at the trailing edge were greater than at the centre and leading of core habitats in

  14. 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

  15. Structural and aerodynamic considerations of an active piezoelectric trailing-edge tab on a helicopter rotor

    Science.gov (United States)

    Murray, Gabriel Jon

    This dissertation is concerned with an active tab for use on a rotorcraft for noise and vibration reduction. The tab is located at the trailing edge of the airfoil. The tab consists of a shim sandwiched by layers of the piezoelectric actuators, macro fiber composites, of varying length. This configuration is similar to a bimorph. The modus operandi is similar to that of a trailing edge flap. The actuators deform the tab, bending it to achieve a tip displacement. This provides a change in the lift, moment, and drag coefficients of the airfoil. By actuating the system at 3/rev to 5/rev, reductions in noise and vibration can be realized. The system was examined and designed around using the UH-60 Blackhawk as the model rotorcraft. The tab is envisioned to operate between 65% to 85% of the main rotor span. The tab's chordwise dimensions considered were 20% and 15% of the blade chord. In order to assess the potential of the tab to change the lift and moment coefficients of the airfoil-tab system, a steady computational fluid dynamics study was conducted. The results were generated via the University of Maryland's Transonic Unsteady Navier-Stokes code. Various tab deflection angles, Mach numbers, and angle-of-attack values were computed. These results were compared to a trailing edge flap of similar size. The comparison shows that the tab produces lift and moment increments similar to that of the trailing edge flap. The design of the tab---composed of both active piezoelectric actuators and passive materials---was conducted using finite element analysis. The objectives were to maximize the tip deflection due to the actuators, while minimizing the deformation due to inertial and aerodynamic forces and loads. The inertial loads (acceleration terms) come from both blade motion, such as flapping and pitch, as well as the rotation of the rotor (centrifugal force). All of these previously mentioned terms cause the tab to undergo undesirable deflections. The original concept

  16. Numerical Investigation of Flow Control Feasibility with a Trailing Edge Flap

    DEFF Research Database (Denmark)

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

    2014-01-01

    This paper concerns a numerical study of employing an adaptive trailing edge flap to control the lift of an airfoil subject to unsteady inflow conditions. The periodically varying inflow is generated by two oscillating airfoils, which are located upstream of the controlled airfoil. To establish the...... solver. In order to more accurately simulate wall bounded flows around the immersed boundary, a modified boundary condition is introduced in the k- ω turbulence model. As an example, turbulent flow over a NACA 64418 airfoil with a deformable trailing edge is investigated. Results from numerical...... control system, a standard PID controller is implemented in a finite volume based incompressible flow solver. An immersed boundary method is applied to treat the problem of simulating a deformable airfoil trailing edge. The flow field is solved using a 2D Reynolds averaged Navier-Stokes finite volume...

  17. Drag reduction, noise and vibration control on Gurney flaps and diverging trailing edges.

    Science.gov (United States)

    Hage, W.; Bechert, D. W.; Meyer, R.

    1999-11-01

    Gurney flaps and divergent trailing edges change the Kutta condition on airfoils, thus producing higher lift. At lower Reynolds numbers (lift to drag ratio of an airfoil can be enhanced. Unfortunatley, however, the drag is also increased due to the form drag of that particular type of trailing edge. In addition, an absolute instability of the wake ensues (i.e., a Karman vortex street) imbedded in the turbulent wake flow. This causes enhanced vibration and noise levels. By an appropriate three-dimensional design of the trailing edge, the absolute instability of the wake can be eliminated. This reduces the drag of the device and removes the single frequency constituent of the fluctuations in the wake. Wind tunnel force measurements on a laminar glider wing and a transonic wing are presented as well as hot-wire measurements in the wake.

  18. Hybrid immersed boundary method for airfoils with a trailing-edge flap

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Behrens, Tim; Shen, Wen Zhong;

    2013-01-01

    In this paper, a hybrid immersed boundary technique has been developed for simulating turbulent flows past airfoils with moving trailing-edge flaps. Over the main fixed part of the airfoil, the equations are solved using a standard body-fitted finite volume technique, whereas the moving trailing......-edge flap is simulated using the immersed boundary method on a curvilinear mesh. An existing in-house-developed flow solver is employed to solve the incompressible Reynolds-Averaged Navier-Stokes equations together with the k-ω turbulence model. To achieve consistent wall boundary conditions at the immersed...... boundaries the k-ωturbulence model is modified and adapted to the local conditions associated with the immersed boundary method. The obtained results show that the hybrid approach is an efficient and accurate method for solving turbulent flows past airfoils with a trailing-edge flap and that flow control...

  19. Potential load reductions on megawatt turbines exposed to wakes using individual-pitch wake compensator and trailing-edge flaps

    DEFF Research Database (Denmark)

    Markou, Helen; Andersen, Peter Bjørn; Larsen, Gunner Chr.

    2011-01-01

    methods that typically focus on either load or power prediction. As a consequence, the wake affected inflow field generated by the DWM formulation opens for control strategies for the individual turbine. Two different control approaches for load reduction on the individual turbines are implemented in the...... multi-body aero-servo-elastic tool HAWC2, developed at Risø-DTU in Denmark, and their potential load reduction capabilities compared: (1) full-blade ‘individual-pitch controllers’ acting as wake compensators and (2) controllers using trailing-edge flaps. Information on the wake inflow conditions...... for the loading conditions of the individual turbines in the farm. The dynamic wake meandering model (DWM) is believed to capture the essential physics of the wake problem, and thus, both load and production aspects can be predicted, which is contrary to the traditional engineering wake prediction...

  20. Preliminary Design and Evaluation of an Airfoil with Continuous Trailing-Edge Flap

    Science.gov (United States)

    Shen, Jinwei; Thornburgh, Robert P.; Kreshock, Andrew R.; Wilbur, Matthew L.; Liu, Yi

    2012-01-01

    This paper presents the preliminary design and evaluation of an airfoil with active continuous trailing-edge flap (CTEF) as a potential rotorcraft active control device. The development of structural cross-section models of a continuous trailing-edge flap airfoil is described. The CTEF deformations with MFC actuation are predicted by NASTRAN and UM/VABS analyses. Good agreement is shown between the predictions from the two analyses. Approximately two degrees of CTEF deflection, defined as the rotation angle of the trailing edge, is achieved with the baseline MFC-PZT bender. The 2D aerodynamic characteristics of the continuous trailing-edge flap are evaluated using a CFD analysis. The aerodynamic efficiency of a continuous trailing-edge flap is compared to that of a conventional discrete trailing-edge flap (DTEF). It is found that the aerodynamic characteristics of a CTEF are equivalent to those of a conventional DTEF with the same deflection angle but with a smaller flap chord. A fluid structure interaction procedure is implemented to predict the deflection of the continuous trailingedge flap under aerodynamic pressure. The reductions in CTEF deflection are overall small when aerodynamic pressure is applied: 2.7% reduction is shown with a CTEF deflection angle of two degrees and at angle of attack of six degrees. In addition, newly developed MFC-PMN actuator is found to be a good supplement to MFC-PZT when applied as the bender outside layers. A mixed MFC-PZT and MFC-PMN bender generates 3% more CTEF deformation than an MFC-PZT only bender and 5% more than an MFC-PMN only bender under aerodynamic loads.

  1. Turbine blades and systems with forward blowing slots

    Science.gov (United States)

    Zuteck, Michael D.; Zalusky, Leigh; Lees, Paul

    2015-09-15

    A blade for use in a wind turbine comprises a pressure side and suction side meeting at a trailing edge and leading edge. The pressure side and suction side provide lift to the turbine blade upon the flow of air from the leading edge to the trailing edge and over the pressure side and suction side. The blade includes one or more openings at the suction side, in some cases between the leading edge and the trailing edge. The one or more openings are configured to provide a pressurized fluid towards the leading edge of the blade, in some cases at an angle between about 0.degree. and 70.degree. with respect to an axis oriented from a centerline of the blade toward the leading edge.

  2. Wind tunnel test on airfoil Riso-B1-18 with an Active Trailing Edge Flap

    DEFF Research Database (Denmark)

    Bak, Christian; Gaunaa, Mac; Andersen, Peter Bjørn;

    2010-01-01

    A wind tunnel test of the wind turbine airfoil Risø-B1-18 equipped with an Active Trailing Edge Flap (ATEF) was carried out. The ATEF was 9% of the total chord, made of piezo electric actuators attached to the trailing edge of a non-deformable airfoil and actuated using an (electric) amplifier. The...

  3. Numerical study of turbulent trailing-edge flows with base cavity effects using URANS

    Science.gov (United States)

    Do, Thau; Chen, Li; Tu, Jiyuan

    2010-10-01

    Turbulent flows over lifting surfaces exhibiting trailing-edge vortex shedding often cause adverse and complex phenomena, such as self-induced vibration and noise. In this paper, a numerical study on flow past a blunt-edged two-dimensional NACA 0015 section and the same section with various base cavity shapes and sizes at high Reynolds numbers has been performed using the unsteady Reynolds-averaged Navier-Stokes (URANS) approach with the realisable κ-ɛ turbulence model. The equations are solved using the control volume method of second-order accuracy in both spatial and time domains. The assessment of the application of URANS for periodic trailing-edge flow has shown that reasonable agreement is achieved for both the time-averaged and fluctuating parameters of interest, although some differences exist in the prediction of the near-wake streamwise velocity fluctuation magnitudes. The predicted Strouhal numbers of flows past the squared-off blunt configuration with varying degrees of bluntness agree well with published experimental measurements. It is found that the intensity of the vortex strengths at the trailing-edge is amplified when the degree of bluntness is increased, leading to an increase in the mean square pressure fluctuations. The numerical prediction shows that the presence of the base cavity at the trailing-edge does not change the inherent Strouhal number of the 2D section examined. However, it does have an apparent effect on the wake structure, local pressure fluctuations and the lift force fluctuations. It is observed that the size of the cavity has more influence on the periodic trailing-edge flow than its shape does.

  4. A modification of Amiet's classical trailing edge noise theory for strictly two dimensional flows

    OpenAIRE

    Sandberg, Richard D.; Sandham, Neil D.

    2007-01-01

    The aim of this report is to derive theoretical expressions for the far-field pressure generated by disturbances convecting over a trailing edge. First, a general calculation of the far-field pressure is discussed. Then the classical theory of Amiet (1976b) is reviewed, listing the most relevant assumptions. Amiet's theory is then revised for two-dimensional flows.

  5. Load alleviation potential of the Controllable Rubber Trailing Edge Flap (CRTEF) in the INDUFLAP project

    DEFF Research Database (Denmark)

    Barlas, Thanasis K.; Bergami, Leonardo; Hansen, Morten Hartvig; Pedersen, Mads Mølgaard; Thomsen, Kenneth; Aagaard Madsen, Helge

    The load alleviation potential of the Controllable Rubber Trailing Edge Flap (CRTEF) is verified on a full Design Load Base (DLB) setup using the aeroelastic code HAWC2, and by investigating a flap configuration for the NREL 5MW Reference Wind Turbine (RWT) model. The performance of the CRTEF...

  6. On the use of Particle Image Velocimetry to predict trailing edge noise

    NARCIS (Netherlands)

    Tuinstra, M.; Probsting, S.; Scarano, F.

    2013-01-01

    The feasibility of aeroacoustic noise predictions based on Particle Image Velocimetry (PIV) measurements is studied. For this purpose, experiments are conducted on a sharp trailing edge (TE) flow developed along a flat plate at free stream velocity of 15m/s. The acoustic emissions were characterized

  7. Development of an improved aeroelastic model for the investigation of vibration reduction in helicopter rotors using trailing edge flaps

    Science.gov (United States)

    Myrtle, Timothy Fitzgerald

    1998-12-01

    This dissertation describes the development of an aeroelastic model of a helicopter rotor incorporating partial span trailing edge flaps on the blade and its application to the investigation of vibration reduction using active control. A new two-dimensional unsteady aerodynamic model for an airfoil/flap combination is described that includes compressibility and unsteady freestream effects. This new aerodynamic model is based on a rational function approximation (RFA) approach. In this approach, oscillatory response data obtained for a selected set of generalized airfoil and flap motions is used to generate an approximate aerodynamic transfer function which can be transformed to the time domain to form a state space aerodynamic model. In this dissertation, a method is described for adapting the conventional RFA approach to include unsteady freestream effects. Excellent agreement is demonstrated between the response of the new aerodynamic model and an exact incompressible solution to the unsteady freestream case. This model provides a complete description of the unsteady flap hinge moments due to airfoil and flap motion, allowing a complete and accurate characterization of control actuation requirements. The structural model utilizes an elastic blade model which includes fully coupled flap-lag-torsional dynamics and includes the effects of moderate deflections. The aeroelastic model is formulated in the time domain, with the coupled trim/response solution obtained using direct numerical integration in combination with autopilot type controller. A conventional higher harmonic control approach is used to investigate vibration reduction. Vibration control studies are performed which compare results using the new aerodynamic model and incompressible quasisteady Theodorsen aerodynamics. Significant differences were observed in the required deflections and control moments, indicating that compressibility and unsteady effects are necessary to properly characterize the

  8. 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...

  9. Secondary wake instabilities of a blunt trailing edge profiled body as a basis for flow control

    Energy Technology Data Exchange (ETDEWEB)

    Naghib-Lahouti, Arash; Doddipatla, Lakshmana Sampat; Hangan, Horia [The University of Western Ontario, The Boundary Layer Wind Tunnel Laboratory, London, ON (Canada)

    2012-06-15

    Flow in the wake of a blunt trailing edge profiled body, comprised of an elliptical leading edge and a rectangular trailing edge, has been investigated experimentally, to identify and characterize the secondary instabilities accompanying the von Karman vortices. The experiments, which involve laser-induced fluorescence for visualization and particle image velocimetry for quantitative measurement of the wake instabilities, cover Reynolds numbers ranging from 250 to 2,150 based on thickness of the body, to include the wake transition regime. The dominant secondary instability appears as spanwise undulations in von Karman vortices, which evolve into pairs of counter-rotating vortices, with features resembling the instability mechanism predicted by Ryan et al. (J Fluid Mech 538:1-29, 2005). Feasibility of a flow control approach based on interaction with the secondary instability using a series of discrete trailing edge injectors has also been investigated. The control approach mitigates the adverse effects of vortex shedding in certain conditions, where it is able to amplify the secondary instability effectively. (orig.)

  10. Effects of leading and trailing edge flaps on the aerodynamics of airfoil/vortex interactions

    Science.gov (United States)

    Hassan, Ahmed A.; Sankar, L. N.; Tadghighi, H.

    1994-01-01

    A numerical procedure has been developed for predicting the two-dimensional parallel interaction between a free convecting vortex and a NACA 0012 airfoil having leading and trailing edge integral-type flaps. Special emphasis is placed on the unsteady flap motion effects which result in alleviating the interaction at subcritical and supercritical onset flows. The numerical procedure described here is based on the implicit finite-difference solutions to the unsteady two-dimensional full potential equation. Vortex-induced effects are computed using the Biot-Savart Law with allowance for a finite core radius. The vortex-induced velocities at the surface of the airfoil are incorporated into the potential flow model via the use of the velocity transpiration approach. Flap motion effects are also modeled using the transpiration approach. For subcritical interactions, our results indicate that trailing edge flaps can be used to alleviate the impulsive loads experienced by the airfoil. For supercritical interactions, our results demonstrate the necessity of using a leading edge flap, rather than a trailing edge flap, to alleviate the interaction. Results for various time-dependent flap motions and their effect on the predicted temporal sectional loads, differential pressures, and the free vortex trajectories are presented

  11. Validations and improvements of airfoil trailing-edge noise prediction models using detailed experimental data

    DEFF Research Database (Denmark)

    Kamruzzaman, M.; Lutz, Th.; Würz, W.;

    2012-01-01

    and far-field radiated noise models capture well the measured peak amplitude level as well as the peak position if the turbulence noise source parameters are estimated properly including turbulence anisotropy effects. Large eddy simulation based computational aeroacoustic computations show good agreements......This paper describes an extensive assessment and a step by step validation of different turbulent boundary-layer trailing-edge noise prediction schemes developed within the European Union funded wind energy project UpWind. To validate prediction models, measurements of turbulent boundary......-layer properties such as two-point turbulent velocity correlations, the spectra of the associated wall pressure fluctuations and the emitted trailing-edge far-field noise were performed in the laminar wind tunnel of the Institute of Aerodynamics and Gas Dynamics, University of Stuttgart. The measurements were...

  12. Influence of blade angle distribution along leading edge on cavitation performance of a centrifugal pump

    Science.gov (United States)

    Xu, Y.; Tan, L.; Cao, S. L.; Wang, Y. C.; Meng, G.; Qu, W. S.

    2015-01-01

    The influence of blade angle distribution along leading edge on cavitation performance of centrifugal pumps is analysed in the present paper. Three sets of blade angle distribution along leading edge for three blade inlet angles are chosen to design nine centrifugal pump impellers. The RNG k-epsilon turbulence model and the Zwart-Gerber-Belamri cavitation model are employed to simulate the cavitation flows in centrifugal pumps with different impellers and the same volute. The numerical results are compared with the experimental data, and the comparison proves that the numerical simulation can accurately predict the cavitation performance of centrifugal pumps. On the basis of the numerical simulations, the pump head variations with pump inlet pressure, and the flow details in centrifugal pump are revealed to demonstrate the influence of blade angle distribution along leading edge on cavitation performances of centrifugal pumps.

  13. Novel swing arm mechanism design for trailing edge flaps on commercial airliner

    OpenAIRE

    Yu, Jie

    2008-01-01

    This thesis will describe the works had been done by the author in the Flying Crane aircraft group design project and the new design of a novel swing arm mechanism which can be applied in the trailing edge high lift devices for this aircraft concept. Flying Crane aircraft is a new generation commercial airliner concept as the result of group design project conducted by China Aviation Industry Corporation I (AVIC I) and Cranfield University. At the end of the group design projec...

  14. Decamber Morphing Concepts by Using a Hybrid Trailing Edge Control Surface

    OpenAIRE

    Yavuz Yaman; İlhan Ozan Tunçöz; Yosheph Yang; Pınar Arslan; Uğur Kalkan; Harun Tıraş; Ercan Gürses; Melin Şahin; Serkan Özgen

    2015-01-01

    The idea of morphing is drawing extensive attention in aerospace technologies. Several different approaches like span, camber, twist, and sweep are finding applications. In this work, the concept of a trailing edge control surface which is capable of performing decamber morphing is explained. The upper and lower parts of the control surface undergo different chordwise elongations and the difference between these displacements gives rise to either camber or decamber morphing. The necessary fo...

  15. Effect of flow obstacles with various leading and trailing edges on critical heat flux

    International Nuclear Information System (INIS)

    A joint investigation has been performed by the University of Ottawa and Chalk River Laboratories that examined the effect of the shape of the leading and trailing edges of the turbulence enhancing devices ('flow obstacles') on critical heat flux (CHF). The objective of this study was to gain a better overall understanding of the limit of CHF improvement for various obstacle designs and the impact of flow conditions on the improvements. (author)

  16. Flat Plate Wake Velocity Statistics Obtained With Circular And Elliptic Trailing Edges

    Science.gov (United States)

    Rai, Man Mohan

    2016-01-01

    The near wake of a flat plate with circular and elliptic trailing edges is investigated with data from direct numerical simulations. The plate length and thickness are the same in both cases. The separating boundary layers are turbulent and statistically identical. Therefore the wake is symmetric in the two cases. The emphasis in this study is on a comparison of the wake-distributions of velocity components, normal intensity and fluctuating shear stress obtained in the two cases.

  17. On the use of Particle Image Velocimetry to predict trailing edge noise

    OpenAIRE

    Tuinstra, M.; Probsting, S.; Scarano, F.

    2013-01-01

    The feasibility of aeroacoustic noise predictions based on Particle Image Velocimetry (PIV) measurements is studied. For this purpose, experiments are conducted on a sharp trailing edge (TE) flow developed along a flat plate at free stream velocity of 15m/s. The acoustic emissions were characterized in the NLR Small Anechoic Wind Tunnel (KAT) by means of microphone measurements. The result is used for benchmarking the PIV based noise predictions. PIV measurements were carried in a low-speed w...

  18. Pneumatic artificial muscles for trailing edge flap actuation: a feasibility study

    International Nuclear Information System (INIS)

    In this study a novel aircraft trailing edge flap actuation system was developed and tested. Pneumatic artificial muscles (PAMs) were used as the driving elements of this system to demonstrate their feasibility and utility as an alternative aerospace actuation technology. A prototype flap/actuator system was integrated into a model wing section and tested on the bench-top under simulated airloads for flight at 100 m s−1 (M = 0.3) and in an open-jet wind tunnel at free stream velocities ranging up to 45 m s−1 (M = 0.13). Testing was performed for actuator pressures ranging from 0.069 to 0.62 MPa (10–90 psi) and actuation frequencies from 0.1 to 31 Hz. Results show that the PAM-driven trailing edge flap system can generate substantial and sustainable dynamic deflections, thereby proving the feasibility of using pneumatic artificial muscle actuators in a trailing edge flap system. Key issues limiting system performance are identified, that should be resolved in future research

  19. Active flow control for reduction of fluctuating aerodynamic forces of a blunt trailing edge profiled body

    Energy Technology Data Exchange (ETDEWEB)

    Naghib-Lahouti, Arash, E-mail: anaghibl@uwo.c [Boundary Layer Wind Tunnel Laboratory, University of Western Ontario, London, Ontario, N6A 5B9 (Canada); Hangan, Horia [Boundary Layer Wind Tunnel Laboratory, University of Western Ontario, London, Ontario, N6A 5B9 (Canada)

    2010-12-15

    Vortex shedding in the wake of two-dimensional bluff bodies is usually accompanied by three dimensional instabilities. These instabilities result in streamwise and vertical vorticity components which occur at a certain spanwise wavelength. The spanwise wavelength of the instabilities ({lambda}{sub Z}) depends on several parameters, including profile geometry and Reynolds number. The objective of the present work is to study the three dimensional wake instabilities for a blunt trailing edge profiled body, comprised of an elliptical leading edge and a rectangular trailing edge, and to manipulate these instabilities to control the aerodynamic forces. Results of numerical simulations of flow around the body at Re(d) = 400, 600, and 1000, as well as planar Laser Induced Fluorescence (LIF) flow visualizations at Re(d) = 600 and 1000 are analyzed to determine the wake vorticity structure and {lambda}{sub Z}. Based on the findings of these analyses, an active flow control mechanism for attenuation of the fluctuating aerodynamic forces on the body is proposed. The flow control mechanism is comprised of a series of trailing edge injection ports distributed across the span, with a spacing equal to {lambda}{sub Z}. Injection of a secondary flow leads to amplification of the three dimensional instabilities and disorganization of the von Karman vortex street. Numerical simulations indicate that the flow control mechanism can attenuate the fluctuating aerodynamic forces at lower Reynolds numbers (Re(d) = 400 and 600) where {lambda}{sub Z} is constant in time. However, the control mechanism loses its effectiveness at Re(d) = 1000, due to the temporal variations of {lambda}{sub Z}.

  20. Experimental investigation of the surface pressure field for prediction of trailing edge noise of wind turbine aerofoils

    DEFF Research Database (Denmark)

    Fischer, Andreas; Aagaard Madsen, Helge; Bertagnolio, Franck

    , was measured with pinhole microphones distributed in streamwise and spanwise direction on the surface of the aerofoil. Two acoustic formulations relating the fluctuating surface pressure field to far field trailing edge noise were investigated. The measurements of the fluctuating surface pressure...... 1.9 million and angles of attack ranging from −10° to 14°. The emitted trailing noise from the aerofoils was measured with a microphone array at a distance of 1.6 m away from the aerofoil. The two-dimensional surface pressure field, which is considered the source of the emitted trailing edge noise...... field were used as input to the model. There was a factor of 2 as difference between the two models. The prediction of the far field trailing edge noise with one model was in excellent agreement with the microphone array measurements in a frequency range of 500-2000 Hz. This opens up the possibility of...

  1. Investigation of the load reduction potential of two trailing edge flap controls using CFD

    DEFF Research Database (Denmark)

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

    2011-01-01

    In this work, a 2D aero‐servo‐elastic model of an airfoil section with 3 degrees of freedom (DOF) based on the 2D CFD solver EllipSys2D to calculate the aerodynamic forces is utilized to calculate the load reduction potential of an airfoil equipped with an adaptive trailing edge flap (ATEF) and...... subjected to a turbulent inflow signal. The employed airfoil model corresponds to a successfully tested prototype airfoil where piezoelectric actuators were used for the flapping. In the present investigation two possible control methods for the flap are compared in their ability to reduce the fluctuating...

  2. Adaptive Trailing Edge Flaps for Active Load Alleviation in a Smart Rotor Configuration

    OpenAIRE

    Bergami, Leonardo; Gaunaa, Mac; Poulsen, Niels Kjølstad; Buhl, Thomas

    2013-01-01

    Denne afhandling omhandler udviklingen af et aktivt smart rotor koncept fra et aeroservoelastisk perspektiv. En aktiv smart rotor er en vindmøllerotor som igennem en kombination af sensorer, reguleringsenhed og aktuatorer, aktivt kan reducere den fluktuerende del af de aerodynamiske kræfter møllen skal modstå. Undersøgelsen omhandler en specifik aktuator type: Adaptive Trailing Edge Flap (ATEF), der består af en kontinuert deformation af den bagerste del af vingeprofilernes tværsnitsform.Der ...

  3. 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.

  4. Development of a resonant trailing-edge flap actuation system for helicopter rotor vibration control

    Science.gov (United States)

    Kim, J.-S.; Wang, K. W.; Smith, E. C.

    2007-12-01

    A resonant trailing-edge flap actuation system for helicopter rotors is developed and evaluated experimentally. The concept involves deflecting each individual trailing-edge flap using a compact resonant piezoelectric actuation system. Each resonant actuation system yields high authority, while operating at a single frequency. By tailoring the natural frequencies of the actuation system (including the piezoelectric actuator and the related mechanical and electrical elements) to the required operating frequencies, one can increase the output authority. The robustness of the device can be enhanced by increasing the high authority bandwidth through electric circuitry design. Such a resonant actuation system (RAS) is analyzed for a full-scale piezoelectric induced-shear tube actuator, and bench-top testing is conducted to validate the concept. An adaptive feed-forward controller is developed to realize the electric network dynamics and adapt to phase variation. The control strategy is then implemented via a digital signal processor (DSP) system. Analysis is also performed to examine the rotor system dynamics in forward flight with piezoelectric resonant actuators, using a perturbation method to evaluate the system's time-varying characteristics. Numerical simulations reveal that the resonant actuator concept can be applied to forward flights as well as to hover conditions.

  5. ATEFlap aerodynamic model, a dynamic stall model including the effects of trailing edge flap deflection

    Energy Technology Data Exchange (ETDEWEB)

    Bergami, L.; Gaunaa, M.

    2012-02-15

    The report presents the ATEFlap aerodynamic model, which computes the unsteady lift, drag and moment on a 2D airfoil section equipped with Adaptive Trailing Edge Flap. The model captures the unsteady response related to the effects of the vorticity shed into the wake, and the dynamics of flow separation a thin-airfoil potential flow model is merged with a dynamic stall model of the Beddoes-Leishmann type. The inputs required by the model are steady data for lift, drag, and moment coefficients as function of angle of attack and flap deflection. Further steady data used by the Beddoes- Leishmann dynamic stall model are computed in an external preprocessor application, which gives the user the possibility to verify, and eventually correct, the steady data passed to the aerodynamic model. The ATEFlap aerodynamic model is integrated in the aeroelastic simulation tool HAWC2, thus al- lowing to simulate the response of a wind turbine with trailing edge flaps on the rotor. The algorithms used by the preprocessor, and by aerodynamic model are presented, and modifications to previous implementations of the aerodynamic model are briefly discussed. The performance and the validity of the model are verified by comparing the dynamic response computed by the ATEFlap with solutions from CFD simulations. (Author)

  6. Identification of secondary instabilities in the near wake of a blunt trailing edge profiled body

    Science.gov (United States)

    Cruikshank, Ross; Zhao, Wenyi; Lavoie, Philippe

    2015-11-01

    Aerodynamic research into blunt trailing edge (BTE) airfoils is driven by their structural and aerodynamic advantages over sharp trailing edge airfoils. However, the wake of BTE airfoils is dominated by a vortex street, which causes increased drag. One method to reduce the spanwise coherence of the vortex street is to generate streamwise vorticity in the wake. Recent evidence suggests that the efficiency of this control method can be improved by forcing at the same wavelength as a secondary instability (SI) of the vortex street, present at Reynolds numbers (based on airfoil thickness, d) above 470. The objective of the present study was to investigate the variation of the SI wavelength at 2000 model was measured using particle image velocimetry, and proper orthogonal decomposition was applied as a filter for measurement noise. It was found that, for a laminar boundary layer, the SI wavelength decreased as Red increased. Following boundary layer transition to turbulence, the SI wavelength was insensitive to Red . This study will also examine the effect of forcing at different wavelengths on the dominant spanwise wavelength of the wake velocity field. The authors gratefully acknowledge the support of the Natural Sciences and Engineering Research Council of Canada.

  7. Coupled flap and edge wise blade motion due to a quadratic wind force definition

    NARCIS (Netherlands)

    Van der Male, P.; Van Dalen, K.N.

    2014-01-01

    The wind force on turbine blades, consisting of a drag and lift component, depends nonlinearly on the relative wind velocity. This relative velocity comprises mean wind speed, wind speed fluctuations and the structural response velocity. The nonlinear wind excitation couples the flap wise and edge w

  8. Effect of airfoil (trailing-edge) thickness on the numerical solution of panel methods based on the Dirichlet boundary condition

    Science.gov (United States)

    Yon, Steven; Katz, Joseph; Plotkin, Allen

    1992-01-01

    The practical limit of airfoil thickness ratio for which acceptable engineering results are obtainable with the Dirichlet boundary-condition-based numerical methods is investigated. This is done by studying the effect of thickness on the calculated pressure distribution near the trailing edge and by comparing the aerodynamic coefficients with available exact solutions. The first objective of this study, owing to the wide use of such computational methods, is to demonstrate the numerical symptoms that occur when the body or wing thickness approaches zero and to increase the awareness of potential users of these methods. Additionally, an effort is made to obtain the practical limits of the trailing-edge thickness where such problems will appear in the flow solution, and to propose some possible cures for very thin airfoils or those with cusped trailing edges.

  9. Computational study of the Risø-B1-18 airfoil with a hinged flap providing variable trailing edge geometry

    DEFF Research Database (Denmark)

    Troldborg, Niels

    2005-01-01

    the baseline airfoil showed excellent agreement with measurements on the same airfoil with the same specified conditions. Furthermore, a more widespread comparison with an advanced potential theory code is presented. The influence of various key parameters, such as flap shape, flap size and......A comprehensive computational study, in both steady and unsteady flow conditions, has been carried out to investigate the aerodynamic characteristics of the Risø-B1.18 airfoil equipped with variable trailing edge geometry as produced by a hinged flap. The function of such flaps should be to...... oscillating frequencies, was investigated so that an optimum design can be suggested for application with wind turbine blades. It is concluded that a moderately curved flap with flap chord to airfoil curve ratio between 0.05 and 0.10 would be an optimum choice....

  10. Coupled flap and edge wise blade motion due to a quadratic wind force definition

    International Nuclear Information System (INIS)

    The wind force on turbine blades, consisting of a drag and lift component, depends nonlinearly on the relative wind velocity. This relative velocity comprises mean wind speed, wind speed fluctuations and the structural response velocity. The nonlinear wind excitation couples the flap wise and edge wise response of a turbine blade. To analyze this motion coupling, an isolated blade is modelled as a continuous cantilever beam and corresponding nonlinear expressions for the drag and lift force are defined. After reduction of the model on the basis of its principal modes, the nonlinear response up to the second order is derived with the help of a Volterra series expansion and the harmonic probing technique. This technique allows for response analysis in the frequency domain, via which the combined flap and edge wise responses can easily be visualized. As a specific case, the characteristics of the NREL5 turbine blades are adopted. For both non-operating and operating conditions, blade responses in a turbulent wave field, based on a Kaimal spectrum, are determined. The second-order responses are shown to cause additional motion coupling, and moreover, are proven not to be negligible straightforwardly

  11. Leading edge film cooling effects on turbine blade heat transfer

    Science.gov (United States)

    Garg, Vijay K.; Gaugler, Raymond E.

    1995-01-01

    An existing three dimensional Navier-Stokes code, modified to include film cooling considerations, has been used to study the effect of spanwise pitch of shower-head holes and coolant to mainstream mass flow ratio on the adiabatic effectiveness and heat transfer coefficient on a film-cooled turbine vane. The mainstream is akin to that under real engine conditions with stagnation temperature = 1900 K and stagnation pressure = 3 MPa. It is found that with the coolant to mainstream mass flow ratio fixed, reducing P, the spanwise pitch for shower-head holes, from 7.5 d to 3.0 d, where d is the hole diameter, increases the average effectiveness considerably over the blade surface. However, when P/d= 7.5, increasing the coolant mass flow increases the effectiveness on the pressure surface but reduces it on the suction surface due to coolant jet lift-off. For P/d = 4.5 or 3.0, such an anomaly does not occur within the range of coolant to mainstream mass flow ratios analyzed. In all cases, adiabatic effectiveness and heat transfer coefficient are highly three-dimensional.

  12. On wake response to asymmetric blowing in spurts from a blunt trailing edge

    Indian Academy of Sciences (India)

    S D Sharma; R R Pant

    2007-02-01

    In the present investigation, a technique has experimentally been evolved with the aim to control the unsteady wake dominated by periodic vortexshedding. The technique uses pulsating surface blowing that is applied asymmetrically just before separation from the blunt trailing edge of a thick aerofoil model. Thus, momentum is injected in spurts in only one of the two separated shear layers. The control parameters are the mass flow rate and the forcing frequency of the pulsating blowing. The technique is particularly effective in suppressing the vortex-shedding when the blowing is moderate and the forcing frequency is twice the natural vortex-shedding frequency. As a consequence of injecting momentum in spurts, there is a significant saving in mass flow required to achieve a condition of the momentumless wake. In spite of the initial conditions being strongly asymmetric, the flow pattern in the wake was observed to quickly assume a remarkable symmetry.

  13. Adaptive Trailing Edge Flaps for Active Load Alleviation in a Smart Rotor Configuration

    DEFF Research Database (Denmark)

    Bergami, Leonardo

    The work investigates the development of an active smart rotor concept from an aero-servo-elastic perspective. An active smart rotor is a wind turbine rotor that, through a combination of sensors, control units and actuators, is able to alleviate the fluctuating part of the aerodynamic loads it has...... to withstand. The investigation focuses on a specific actuator type: the Adaptive Trailing Edge Flap (ATEF), which introduces a continuous deformation of the aft part of the airfoil camber-line. An aerodynamic model that accounts for the steady and unsteady effects of the flap deflection on a 2D...... energy capture below rated conditions by using the flaps. Two model based control algorithms are developed to actively alleviate the fatigue loads on the smart rotor with ATEF. The first algorithm features a linear quadratic regulator with periodic disturbance rejection, and controls the deflection of...

  14. Effects of Angle of Attack and Velocity on Trailing Edge Noise

    Science.gov (United States)

    Hutcheson, Florence V.; Brooks, Thomas F.

    2006-01-01

    Trailing edge (TE) noise measurements for a NACA 63-215 airfoil model are presented, providing benchmark experimental data for a cambered airfoil. The effects of flow Mach number and angle of attack of the airfoil model with different TE bluntnesses are shown. Far-field noise spectra and directivity are obtained using a directional microphone array. Standard and diagonal removal beamforming techniques are evaluated employing tailored weighting functions for quantitatively accounting for the distributed line character of TE noise. Diagonal removal processing is used for the primary database as it successfully removes noise contaminates. Some TE noise predictions are reported to help interpret the data, with respect to flow speed, angle of attack, and TE bluntness on spectral shape and peak levels. Important findings include the validation of a TE noise directivity function for different airfoil angles of attack and the demonstration of the importance of the directivity function s convective amplification terms.

  15. Fracture analysis of adhesive joints in wind turbine blades

    DEFF Research Database (Denmark)

    Eder, Martin Alexander; Bitsche, Robert

    2015-01-01

    Modern wind turbine rotor blades are usually made from fibre-reinforced composite subcomponents. In the final assembly stage, these subcomponents are bonded together by several adhesive joints. One important adhesive joint is situated at the trailing edge, which refers to the downstream edge where...... the air-flow rejoins and leaves the blade. Maintenance inspections of wind turbine rotor blades show that among other forms of damage, local debonding of the shells along the trailing edge is a frequent failure type. The cause of trailing edge failure in wind turbine blades is complex, and detailed...... examination, the paper elucidates the influence of geometrical non-linearity in form of local buckling on both the increase of the energy release rate and the change of mode mixity. First, experimental results on adhesively bonded small-scale subcomponents are presented. Thereafter, a practical approach is...

  16. Investigation of film cooling on the leading edge of turbine blade based on detached eddy simulation

    Institute of Scientific and Technical Information of China (English)

    LIANG JunYu; KANG Shun

    2012-01-01

    In order to assess the influences of curved hole passage on cooling effectiveness and flow structure of turbine blade leading edge,the detached eddy simulation is applied to numerically investigate the AGTB turbine cascade under the condition of global blowing ratio M=0.7.The straight or curved cooling holes are located at either the pressure or suction side near the leading edge.The analysis and discussion focus on the local turbulence structure; influence of pressure gradient on the structure,and distribution of cooling effectiveness on the blade surface.The numerical results show that cooling hole with curved passage could bring positive impact on the increase of the local cooling effectiveness.On the suction side,the increased cooling effectiveness could be about 82% and about 77% on the pressure side,compared to the conventional straight hole.

  17. Effect of leading- and trailing-edge flaps on clipped delta wings with and without wing camber at supersonic speeds

    Science.gov (United States)

    Hernandez, Gloria; Wood, Richard M.; Covell, Peter F.

    1994-01-01

    An experimental investigation of the aerodynamic characteristics of thin, moderately swept fighter wings has been conducted to evaluate the effect of camber and twist on the effectiveness of leading- and trailing-edge flaps at supersonic speeds in the Langley Unitary Plan Wind Tunnel. The study geometry consisted of a generic fuselage with camber typical of advanced fighter designs without inlets, canopy, or vertical tail. The model was tested with two wing configurations an uncambered (flat) wing and a cambered and twisted wing. Each wing had an identical clipped delta planform with an inboard leading edge swept back 65 deg and an outboard leading edge swept back 50 deg. The trailing edge was swept forward 25 deg. The leading-edge flaps were deflected 4 deg to 15 deg, and the trailing-edge flaps were deflected from -30 deg to 10 deg. Longitudinal force and moment data were obtained at Mach numbers of 1.60, 1.80, 2.00, and 2.16 for an angle-of-attack range 4 deg to 20 deg at a Reynolds number of 2.16 x 10(exp 6) per foot and for an angle-of-attack range 4 deg to 20 deg at a Reynolds number of 2.0 x 10(exp 6) per foot. Vapor screen, tuft, and oil flow visualization data are also included.

  18. Gas–liquid flow in stirred reactors: Trailing vortices and gas accumulation behind impeller blades

    NARCIS (Netherlands)

    Ranade, Vivek V.; Deshpande, Vaibhav R.

    1999-01-01

    In a gas–liquid stirred reactor, gas tends to accumulate in low-pressure regions behind the impeller blades. Such gas accumulation significantly alters impeller performance characteristics. We have computationally investigated gas–liquid flow generated by a Rushton (disc) turbine. Rotating Rushton t

  19. 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.

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

    Science.gov (United States)

    Montgomery, Stuart K.

    1999-01-01

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

  1. Effect of leading-edge porosity on blade-vortex interaction noise

    Science.gov (United States)

    Lee, Soogab

    1993-01-01

    The effect of the porous leading-edge of an airfoil on the blade-vortex interaction noise, which dominates far-field acoustic spectrum of the helicopter, is investigated. The thin-layer Navier-Stokes equations are solved with a high-order upwind-biased scheme and a multizonal grid system. The Baldwin-Lomax turbulence model is modified for considering transpiration on the surface. The amplitudes of the propagating acoustic wave in the near-field are calculated directly from the computation. The porosity effect on the surface is modeled. Results show leading-edge transpiration can suppress pressure fluctuations at the leading-edge during BVI, and consequently reduce the amplitude of propagating noise by 30 percent at maximum in the near-field. The effect of porosity factor on the noise level is also investigated.

  2. Dynamics of a pneumatic artificial muscle actuation system driving a trailing edge flap

    Science.gov (United States)

    Woods, Benjamin K. S.; Kothera, Curt S.; Wang, Gang; Wereley, Norman M.

    2014-09-01

    This study presents a time domain dynamic model of an antagonistic pneumatic artificial muscle (PAM) driven trailing edge flap (TEF) system for next generation active helicopter rotors. Active rotor concepts are currently being widely researched in the rotorcraft community as a means to provide a significant leap forward in performance through primary aircraft control, vibration mitigation and noise reduction. Recent work has shown PAMs to be a promising candidate for active rotor actuation due to their combination of high force, large stroke, light weight, and suitable bandwidth. When arranged into biologically inspired agonist/antagonist muscle pairs they can produce bidirectional torques for effectively driving a TEF. However, there are no analytical dynamic models in the literature that can accurately capture the behavior of such systems across the broad range of frequencies required for this demanding application. This work combines mechanical, pneumatic, and aerodynamic component models into a global flap system model developed for the Bell 407 rotor system. This model can accurately predict pressure, force, and flap angle response to pneumatic control valve inputs over a range of operating frequencies from 7 to 35 Hz (1/rev to 5/rev for the Bell 407) and operating pressures from 30 to 90 psi.

  3. Decamber Morphing Concepts by Using a Hybrid Trailing Edge Control Surface

    Directory of Open Access Journals (Sweden)

    Yavuz Yaman

    2015-07-01

    Full Text Available The idea of morphing is drawing extensive attention in aerospace technologies. Several different approaches like span, camber, twist, and sweep are finding applications. In this work, the concept of a trailing edge control surface which is capable of performing decamber morphing is explained. The upper and lower parts of the control surface undergo different chordwise elongations and the difference between these displacements gives rise to either camber or decamber morphing. The necessary force is achieved by the help of servo actuators. During the design, the structural analyses were done to determine the best viable options for the number of servo actuators, the location of the servo actuators, and the material properties used in the control surface. The control surface was designed of aluminum, composite and compliant materials hence was called a hybrid one. The structural analyses were conducted by using ANSYS® Workbench v14.0 package program. After finding the best viable design, which was made for in vacuo condition, the proposed design was also verified under the simulated aerodynamic loading. The aerodynamic loads were obtained from CFD analyses which were done with SU2 V3.2.3 open-source flow solver.

  4. Dynamics of a pneumatic artificial muscle actuation system driving a trailing edge flap

    International Nuclear Information System (INIS)

    This study presents a time domain dynamic model of an antagonistic pneumatic artificial muscle (PAM) driven trailing edge flap (TEF) system for next generation active helicopter rotors. Active rotor concepts are currently being widely researched in the rotorcraft community as a means to provide a significant leap forward in performance through primary aircraft control, vibration mitigation and noise reduction. Recent work has shown PAMs to be a promising candidate for active rotor actuation due to their combination of high force, large stroke, light weight, and suitable bandwidth. When arranged into biologically inspired agonist/antagonist muscle pairs they can produce bidirectional torques for effectively driving a TEF. However, there are no analytical dynamic models in the literature that can accurately capture the behavior of such systems across the broad range of frequencies required for this demanding application. This work combines mechanical, pneumatic, and aerodynamic component models into a global flap system model developed for the Bell 407 rotor system. This model can accurately predict pressure, force, and flap angle response to pneumatic control valve inputs over a range of operating frequencies from 7 to 35 Hz (1/rev to 5/rev for the Bell 407) and operating pressures from 30 to 90 psi. (paper)

  5. Characterization of base pressure fluctuations in a blunt trailing edge wake with three-dimensional forcing

    Science.gov (United States)

    Clark, Heather; Lavoie, Philippe

    2015-11-01

    The wakes of many nominally two-dimensional bluff bodies exhibit multiple intrinsic three-dimensional instabilities whose spatiotemporal structure and growth rate depend on geometry and Reynolds number. Here, these features are investigated experimentally for a blunt trailing edge profiled body using simultaneous measurements of velocity and fluctuating surface pressure on the model rear face near separation. Passive three-dimensional forcing of the wake is implemented with an array of vortex generators that are distributed according to the characteristic spanwise wavelength of the dominant secondary instability. For a Reynolds number of 8000 based on model thickness, the control strategy is found to increase the base pressure coefficient by 26% while globally reducing the amplitude of base pressure fluctuations, relative to the unforced flow. Additionally, amplitude modulation of the pressure signals that is observed in the natural wake decreases in strength with distributed forcing as a result of the modified three-dimensional flow structure. The spanwise distribution of pressure will be further examined for the baseline and controlled flows via temporal spectral analysis and spatial modal decomposition.

  6. Experimental Investigation of Innovative Internal Trailing Edge Cooling Configurations with Pentagonal Arrangement and Elliptic Pin Fin

    Directory of Open Access Journals (Sweden)

    L. Tarchi

    2008-01-01

    Full Text Available This paper describes a heat transfer experimental study of four different internal trailing edge cooling configurations based on pin fin schemes. The aim of the study is the comparison between innovative configurations and standard ones. So, a circular pin fin configuration with an innovative pentagonal scheme is compared to a standard staggered scheme, while two elliptic pin fin configurations are compared to each other turning the ellipse from the streamwise to the spanwise direction. For each configuration, heat transfer and pressure loss measurements were made keeping the Mach number fixed at 0.3 and varying the Reynolds number from 9000 to 27000. In order to investigate the overall behavior of both endwall and pedestals, heat transfer measurements are performed using a combined transient technique. Over the endwall surface, the classic transient technique with thermochromic liquid crystals allows the measurement of a detailed heat transfer coefficient (HTC map. Pin fins are made of high thermal conductivity material, and an inverse data reduction method based on a finite element code allows to evaluate the mean HTC of each pin fin. Results show that the pentagonal arrangement generates a nonuniform HTC distribution over the endwall surface, while, in terms of average values, it is equivalent to the staggered configuration. On the contrary, the HTC map of the two elliptic configurations is similar, but the spanwise arrangement generates higher heat transfer coefficients and pressure losses.

  7. Evaluation of Load Analysis Methods for NASAs GIII Adaptive Compliant Trailing Edge Project

    Science.gov (United States)

    Cruz, Josue; Miller, Eric J.

    2016-01-01

    The Air Force Research Laboratory (AFRL), NASA Armstrong Flight Research Center (AFRC), and FlexSys Inc. (Ann Arbor, Michigan) have collaborated to flight test the Adaptive Compliant Trailing Edge (ACTE) flaps. These flaps were installed on a Gulfstream Aerospace Corporation (GAC) GIII aircraft and tested at AFRC at various deflection angles over a range of flight conditions. External aerodynamic and inertial load analyses were conducted with the intention to ensure that the change in wing loads due to the deployed ACTE flap did not overload the existing baseline GIII wing box structure. The objective of this paper was to substantiate the analysis tools used for predicting wing loads at AFRC. Computational fluid dynamics (CFD) models and distributed mass inertial models were developed for predicting the loads on the wing. The analysis tools included TRANAIR (full potential) and CMARC (panel) models. Aerodynamic pressure data from the analysis codes were validated against static pressure port data collected in-flight. Combined results from the CFD predictions and the inertial load analysis were used to predict the normal force, bending moment, and torque loads on the wing. Wing loads obtained from calibrated strain gages installed on the wing were used for substantiation of the load prediction tools. The load predictions exhibited good agreement compared to the flight load results obtained from calibrated strain gage measurements.

  8. Locating the Trailing Edge of the Circumbinary Ring in the KH 15D System

    CERN Document Server

    Capelo, Holly L; Leggett, S K; Hamilton, Catrina M; Johnson, John A

    2012-01-01

    Following two years of complete occultation of both stars by its opaque circumbinary ring, the binary T Tauri star KH 15D has abruptly brightened again during apastron phases, reaching I = 15 mag. Here, we show that the brightening is accompanied by a change in spectral class from K6/K7 (the spectral class of star A) to ~K1, and a bluing of the system in V-I by about 0.3 mag. A radial velocity measurement confirms that, at apastron, we are now seeing direct light from star B, which is more luminous and of earlier spectral class than star A. Evidently, the trailing edge of the occulting screen has just become tangent to one anse of star B's projected orbit. This confirms a prediction of the precession models, supports the view that the tilted ring is self-gravitating, and ushers in a new era of the system's evolution that should be accompanied by the same kind of dramatic phenomena observed from 1995-2009. It also promotes KH 15D from a single-lined to a double-lined eclipsing binary, greatly enhancing its val...

  9. Airfoil trailing edge flow measurements and comparison with theory, incorporating open wind tunnel corrections

    Science.gov (United States)

    Brooks, T. F.; Marcolini, M. A.; Pope, D. S.

    1984-01-01

    Trailing edge data for boundary layer-near wake thickness parameters are given for airfoils and flat plates. Reynolds number effects are examined as a function of model size, velocity and boundary layer tripping. These data expand that presented previously by the authors particularly for airfoil non-zero angles of attack. Comparisons are made here with boundary layer calculations using potential flow modeling and a well documented two-dimensional finite-difference method for laminar and turbulent boundary layers. Open wind tunnel corrections to angle of attack and camber are developed and are incorporated in the potential flow modeling to assure correct comparisons for non-zero angles of attack. It was found that although the open tunnel flow turbulence affected boundary layer transition for the higher velocities the theory successfully 'brackets' the data. Comparisons demonstrate the degree of accuracy one might expect for the prediction of boundary layer thickness parameters when given only geometry and nominal flow conditions as input to boundary layer codes.

  10. Analysis of the separated boundary layer flow on the surface and in the wake of blunt trailing edge airfoils

    Science.gov (United States)

    Goradia, S. H.; Mehta, J. M.; Shrewsbury, G. S.

    1977-01-01

    The viscous flow phenomena associated with sharp and blunt trailing edge airfoils were investigated. Experimental measurements were obtained for a 17 percent thick, high performance GAW-1 airfoil. Experimental measurements consist of velocity and static pressure profiles which were obtained by the use of forward and reverse total pressure probes and disc type static pressure probes over the surface and in the wake of sharp and blunt trailing edge airfoils. Measurements of the upper surface boundary layer were obtained in both the attached and separated flow regions. In addition, static pressure data were acquired, and skin friction on the airfoil upper surface was measured with a specially constructed device. Comparison of the viscous flow data with data previously obtained elsewhere indicates reasonable agreement in the attached flow region. In the separated flow region, considerable differences exist between these two sets of measurements.

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

    DEFF Research Database (Denmark)

    Bergami, Leonardo

    This book presents the formulation of an aero-servo-elastic model for a wind turbine rotor equipped with Adaptive Trailing Edge Flaps (ATEF), a smart rotor configuration. As the name suggests, an aero-servo-elastic model consists of three main components: an aerodynamic model, a structural model...... control the trailing edge flap deflection to actively reduce the fatigue loads on the structure. The performance of the smart rotor configuration and its control algorithms are finally quantified by aero-servo-elastic simulations of the smart rotor turbine operating in a standard turbulent wind field....... code HAWC2. The investigated smart rotor configuration mainly aims at alleviating the fatigue loads the turbine rotor has to withstand during normal operation. First, the characteristics of the prevailing loads are identified; then, two model-based control algorithms are outlined: the algorithms...

  12. LES of High-Reynolds-Number Coanda Flow Separating from a Rounded Trailing Edge of a Circulation Control Airfoil

    Science.gov (United States)

    Nichino, Takafumi; Hahn, Seonghyeon; Shariff, Karim

    2010-01-01

    This slide presentation reviews the Large Eddy Simulation of a high reynolds number Coanda flow that is separated from a round trailing edge of a ciruclation control airfoil. The objectives of the study are: (1) To investigate detailed physics (flow structures and statistics) of the fully turbulent Coanda jet applied to a CC airfoil, by using LES (2) To compare LES and RANS results to figure out how to improve the performance of existing RANS models for this type of flow.

  13. 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.

  14. 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

  15. Optimal design of wind turbine blades equipped with flaps

    OpenAIRE

    Wiratama, I. Kade; Maheri, Alireza

    2014-01-01

    As a result of the significant growth of wind turbines in size, blade load control has become the main challenge for large wind turbines. Many advanced techniques have been investigated aiming at developing control devices to ease blade loading. Amongst them, trailing edge flaps have been proven as effective devices for load alleviation. The present study aims at investigating the potential benefits of flaps in enhancing the energy capture capabilities rather than blade load alleviation. A so...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    A conventional rotor control system restricted at 1/rev frequency component is unable to vary the hub vibratory loads and the aeroacoustic noise, which exist in high frequency components. Various active rotor control methodologies have been examined in the literature to alleviate the problem of e...

  17. Atmospheric Full Scale Testing of a Morphing Trailing Edge Flap System for Wind Turbine Blades

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Aagaard Madsen, Helge

    2015-01-01

    Risø Campus of DTU Wind Energy in Denmark. The design and instrumentation of the wing section and the AFS are described. The general description and objectives of the rotating test rig at the Risø campus of DTU are presented, along with an overview of sensors on the setup and the test cases. The post...

  18. Theoretical analysis for passage and exit flow of two dimensional centrifugal impeller with leading edge cavitation. Effects of blade number and blade angle

    Energy Technology Data Exchange (ETDEWEB)

    Nishiyama, Hideya

    1988-07-25

    Any analytic study of a centrifugal impeller with a leading edge cavitation is concentrated only on blade or cavity characteristics. Therefore, internal flow condition, especially exit flow, has many indistinctness. Considering that, analysis of flow inside the centrifugal impeller casing and at its exit was performed by the singularity method. In the inside flow of the centrifugal impeller casing, cavitation rear end distortion, cavitation area, relative velocity distribution, pressure inside the cavity, iso-hydrostatic line distribution were examined. In the exit flow, hydrostatic distribution, flow angle distribution, slip velocity distribution, slip constant, blade efficiency, and comparison between obtained and existing slip constant values were examined. As a result, the flow inside the centrifugal impeller in front cavity is found to vary with the number or angle of blades because of the large cavitation area and different from that of no cavitation. The exit flow in the front cavity is different from that at the center of the cavity. The rate of change of slip constant and blade efficiency is large in the front cavity; it is larger when the impeller has fewer blades a lager blade angle. (13 figs, 10 refs)

  19. Experimental investigation of the leading edge vortex on vertical axis wind turbine blades

    Science.gov (United States)

    Dunne, Reeve; McKeon, Beverley

    2012-11-01

    A NACA 0018 airfoil is pitched about the leading edge over a large angle of attack range (+/- ~40°) at a chord Reynolds number of 110,000 to simulate the flow over a single blade in a vertical axis wind turbine (VAWT). Particle image velocimetry (PIV) measurements are made to investigate the effects of pitching on leading edge vortex (LEV) development and separation. Time resolved experiments are performed to track vortex formation and convection over the airfoil for sinusoidal pitching motions corresponding to a VAWT trajectory as well as impulsive pitch up and pitch down motions. These results are compared to the wake of steady, post stall, high angle of attack airfoils (α =20° -30°). The characteristics of the leading edge vortex development and subsequent separation from the airfoil are discussed, with a view to characterizing its effect on power generation with VAWTs and future flow control strategies for turbine performance improvement. Funding from the Gordon and Betty Moore Foundation is gratefully acknowledged.

  20. Numerical modeling of the vortex breakdown phenomenon on a delta wing with trailing-edge jet-flap

    Energy Technology Data Exchange (ETDEWEB)

    Kyriakou, Marilena; Missirlis, Dimitrios [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, Egnatia street, 54124 Thessaloniki (Greece); Yakinthos, Kyros, E-mail: kyak@auth.g [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, Egnatia street, 54124 Thessaloniki (Greece)

    2010-12-15

    The flow development over delta wings is highly complicated since the interaction of the angle of attack with the delta-wing geometry leads to the appearance of a pair of well-organized counter-rotating leading-edge vortical structures. For relatively moderate angles of attack, these vortices remain robust and contribute to the enhancement of the overall lift performance. However, at higher angles of attack the vortices develop instabilities leading to the well-known vortex breakdown phenomenon, resulting in a deterioration of the aerodynamic properties. Thus, delaying vortex breakdown at higher angles of attack, is important and for this reason various techniques have been developed to control the breakdown mechanism. Such a technique is the use of trailing-edge jet-flaps. In the present work, an attempt to model the vortex breakdown together with its control, above a delta wing at high angles of attack, for cases with and without a trailing-edge jet-flap, is presented. To model the turbulent stresses, the low-Reynolds-number stress-omega model was used. The computational results were in good agreement with the available experimental data regarding the prediction of the onset of vortex breakdown and showed that the use of jet-flaps can lead to a significant delay of the breakdown process.

  1. Numerical modeling of the vortex breakdown phenomenon on a delta wing with trailing-edge jet-flap

    International Nuclear Information System (INIS)

    The flow development over delta wings is highly complicated since the interaction of the angle of attack with the delta-wing geometry leads to the appearance of a pair of well-organized counter-rotating leading-edge vortical structures. For relatively moderate angles of attack, these vortices remain robust and contribute to the enhancement of the overall lift performance. However, at higher angles of attack the vortices develop instabilities leading to the well-known vortex breakdown phenomenon, resulting in a deterioration of the aerodynamic properties. Thus, delaying vortex breakdown at higher angles of attack, is important and for this reason various techniques have been developed to control the breakdown mechanism. Such a technique is the use of trailing-edge jet-flaps. In the present work, an attempt to model the vortex breakdown together with its control, above a delta wing at high angles of attack, for cases with and without a trailing-edge jet-flap, is presented. To model the turbulent stresses, the low-Reynolds-number stress-omega model was used. The computational results were in good agreement with the available experimental data regarding the prediction of the onset of vortex breakdown and showed that the use of jet-flaps can lead to a significant delay of the breakdown process.

  2. Smart rotor modeling aero-servo-elastic modeling of a smart rotor with adaptive trailing edge flaps

    CERN Document Server

    Bergami, Leonardo

    2014-01-01

    A smart rotor is a wind turbine rotor that, through a combination of sensors, control units and actuators actively reduces the variation of the aerodynamic loads it has to withstand. Smart rotors feature?promising load alleviation potential and might provide the technological breakthrough required by the next generation of large wind turbine rotors.The book presents the aero-servo-elastic model of a smart rotor with Adaptive Trailing Edge Flaps for active load alleviation and provides an insight on the rotor aerodynamic, structural and control modeling. A novel model for the unsteady aerodynam

  3. Breakdown and tracking properties of rubber materials for wind turbine blades

    DEFF Research Database (Denmark)

    Garolera, Anna Candela; Holboell, Joachim; Henriksen, Mogens

    2012-01-01

    The use of rubber materials in wind turbine blades, for example in controllable trailing edge flaps, requires research on their behavior under heavy exposure to electric fields and electrical discharges. Since the complex construction of blades usually involves several and often inhomogeneous mat...

  4. Breakdown and tracking properties of rubber materials for wind turbine blades

    DEFF Research Database (Denmark)

    Garolera, Anna Candela; Holboell, Joachim; Henriksen, Mogens

    The use of rubber materials in wind turbine blades, for example in controllable trailing edge flaps, requires research on their behavior under heavy exposure to electric fields and electrical discharges. Since the complex construction of blades usually involves several and often inhomogeneous mat...

  5. Damage Detection in an Operating Vestas V27 Wind Turbine Blade by use of Outlier Analysis

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Tcherniak, Dmitri; Damkilde, Lars

    2015-01-01

    The present paper explores the application of a well-established vibration-based damage detection method to an operating Vestas V27 wind turbine blade. The blade is analyzed in a total of four states, namely, a healthy one plus three damaged ones in which trailing edge openings of increasing sizes...

  6. 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.

  7. AMELIA CESTOL Test: Acoustic Characteristics of Circulation Control Wing with Leading- and Trailing-Edge Slot Blowing

    Science.gov (United States)

    Horne, William C.; Burnside, Nathan J.

    2013-01-01

    The AMELIA Cruise-Efficient Short Take-off and Landing (CESTOL) configuration concept was developed to meet future requirements of reduced field length, noise, and fuel burn by researchers at Cal Poly, San Luis Obispo and Georgia Tech Research Institute under sponsorship by the NASA Fundamental Aeronautics Program (FAP), Subsonic Fixed Wing Project. The novel configuration includes leading- and trailing-edge circulation control wing (CCW), over-wing podded turbine propulsion simulation (TPS). Extensive aerodynamic measurements of forces, surfaces pressures, and wing surface skin friction measurements were recently measured over a wide range of test conditions in the Arnold Engineering Development Center(AEDC) National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Ft Wind Tunnel. Acoustic measurements of the model were also acquired for each configuration with 7 fixed microphones on a line under the left wing, and with a 48-element, 40-inch diameter phased microphone array under the right wing. This presentation will discuss acoustic characteristics of the CCW system for a variety of tunnel speeds (0 to 120 kts), model configurations (leading edge(LE) and/or trailing-edge(TE) slot blowing, and orientations (incidence and yaw) based on acoustic measurements acquired concurrently with the aerodynamic measurements. The flow coefficient, Cmu= mVSLOT/qSW varied from 0 to 0.88 at 40 kts, and from 0 to 0.15 at 120 kts. Here m is the slot mass flow rate, VSLOT is the slot exit velocity, q is dynamic pressure, and SW is wing surface area. Directivities at selected 1/3 octave bands will be compared with comparable measurements of a 2-D wing at GTRI, as will as microphone array near-field measurements of the right wing at maximum flow rate. The presentation will include discussion of acoustic sensor calibrations as well as characterization of the wind tunnel background noise environment.

  8. The interbranchial lymphoid tissue of Atlantic Salmon (Salmo salar L) extends as a diffuse mucosal lymphoid tissue throughout the trailing edge of the gill filament

    DEFF Research Database (Denmark)

    Dalum, Alf S; Austbø, Lars; Bjørgen, Håvard;

    2015-01-01

    The teleost gill forms an extensive, semipermeable barrier that must tolerate intimate contact with the surrounding environment and be able to protect the body from external pathogens. The recent discovery of the interbranchial lymphoid tissue (ILT) has initiated an anatomical and functional...... described ILT and the filament trailing edge lymphoid tissue suggest a close functional and anatomical relationship. We propose that the anatomical definition of the ILT must be broadened to include both the previously described ILT (to be renamed proximal ILT) and the trailing edge lymphoid tissue (to be...

  9. 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.

  10. Towards an Industrial Manufactured Morphing Trailing Edge Flap System for Wind Turbines

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Løgstrup Andersen, Tom; Bergami, Leonardo;

    Several numerical studies in the past 10 years have shown big potentials for load reduction on MW turbines using distributed control for alleviation of the fluctuating loads along the blade span. However, the requirements by the wind turbine industry of robust actuator solutions where the stronge......, is transferred into an industrial manufacturing process and tested on a novel rotating test rig. The industrial partners are Rehau, Hydratech Industries and Dansk Gummi Industri....

  11. Effects of torsion frequencies on rotor performance and structural loads with trailing edge flap

    International Nuclear Information System (INIS)

    The effects of variation of blade torsion frequency on rotor performance and structural loads are investigated for a 1/rev active flap rotor and baseline rotor (no active control). The UH-60A four-bladed articulated main rotor is studied at a high-speed forward flight condition. The torsion frequencies are varied by modifying the spanwise torsional stiffness of the blade and/or the pitch link stiffness. First, a parametric/optimization study on the flap deployment schedule is carried out using lifting-line comprehensive analysis for the soft, baseline, and stiff rotor configurations, and then a higher fidelity coupled computational fluid dynamics–computational structural dynamics analysis is carried out for the optimal flap deployment. It is shown that with the soft rotor there is degradation in performance—of about 6% with respect to the baseline rotor in the case where the flaps are not activated, and of about 1% if flap deflections are applied. On the other hand, for the stiff rotor there is a slight improvement in performance of about 2.3% when the flaps are not activated, and no appreciable change in the case where active flap deflections are applied. It appears that the peak performance achievable with using active flaps on a baseline stiffness rotor cannot be further improved significantly by varying the torsional frequencies. Variation of torsion frequency does not appear to have a significant influence on blade torsion moments and pitch link loads, although the 1/rev flap activation examined has an important role. (paper)

  12. A mechanism for mitigation of blade-vortex interaction using leading edge blowing flow control

    Science.gov (United States)

    Weiland, Chris; Vlachos, Pavlos P.

    2009-09-01

    The interaction of a vortical unsteady flow with structures is often encountered in engineering applications. Such flow structure interactions (FSI) can be responsible for generating significant loads and can have many detrimental structural and acoustic side effects, such as structural fatigue, radiated noise and even catastrophic results. Amongst the different types of FSI, the parallel blade-vortex interaction (BVI) is the most common, often encountered in helicopters and propulsors. In this work, we report on the implementation of leading edge blowing (LEB) active flow control for successfully minimizing the parallel BVI. Our results show reduction of the airfoil vibrations up to 38% based on the root-mean-square of the vibration velocity amplitude. This technique is based on displacing an incident vortex using a jet issued from the leading edge of a sharp airfoil effectively increasing the stand-off distance of the vortex from the body. The effectiveness of the method was experimentally analyzed using time-resolved digital particle image velocimetry (TRDPIV) recorded at an 800 Hz rate, which is sufficient to resolve the spatio-temporal dynamics of the flow field and it was combined with simultaneous accelerometer measurements of the airfoil, which was free to oscillate in a direction perpendicular to the freestream. Analysis of the flow field spectra and a Proper Orthogonal Decomposition (POD) of the TRDPIV data of the temporally resolved planar flow fields indicate that the LEB effectively modified the flow field surrounding the airfoil and increased the convecting vortices stand-off distance for over half of the airfoil chord length. It is shown that LEB also causes a redistribution of the flow field spectral energy over a larger range of frequencies.

  13. A mechanism for mitigation of blade-vortex interaction using leading edge blowing flow control

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, Chris; Vlachos, Pavlos P. [Virginia Tech, Department of Mechanical Engineering, Blacksburg, VA (United States)

    2009-09-15

    The interaction of a vortical unsteady flow with structures is often encountered in engineering applications. Such flow structure interactions (FSI) can be responsible for generating significant loads and can have many detrimental structural and acoustic side effects, such as structural fatigue, radiated noise and even catastrophic results. Amongst the different types of FSI, the parallel blade-vortex interaction (BVI) is the most common, often encountered in helicopters and propulsors. In this work, we report on the implementation of leading edge blowing (LEB) active flow control for successfully minimizing the parallel BVI. Our results show reduction of the airfoil vibrations up to 38% based on the root-mean-square of the vibration velocity amplitude. This technique is based on displacing an incident vortex using a jet issued from the leading edge of a sharp airfoil effectively increasing the stand-off distance of the vortex from the body. The effectiveness of the method was experimentally analyzed using time-resolved digital particle image velocimetry (TRDPIV) recorded at an 800 Hz rate, which is sufficient to resolve the spatio-temporal dynamics of the flow field and it was combined with simultaneous accelerometer measurements of the airfoil, which was free to oscillate in a direction perpendicular to the freestream. Analysis of the flow field spectra and a Proper Orthogonal Decomposition (POD) of the TRDPIV data of the temporally resolved planar flow fields indicate that the LEB effectively modified the flow field surrounding the airfoil and increased the convecting vortices stand-off distance for over half of the airfoil chord length. It is shown that LEB also causes a redistribution of the flow field spectral energy over a larger range of frequencies. (orig.)

  14. Computer programs for calculating partially cavitating blunt trailing edged cascade flows in nonlinear theory

    Science.gov (United States)

    Maekawa, S.; Furuya, O.

    1980-01-01

    In addition to the previously developed partially cavitating cascade theory, two new flow models were constructed in search of a better flow model for determining accurate force coefficients. Effort has been made for obtaining (1) physically acceptable flows, particularly the location of cavity boundary and (2) smooth matching of the flow characteristics between the partially cavitating and super-cavitating flow regimes. Based on the numerical results made with these flow models for practical blade profiles taken after a supercavitating propeller, it was found that no single flow model developed could handle the complete set of cascade geometries and incidence angles. One theory was supplemental to the other and no definite guideline was discovered for selection of an appropriate flow model for a specified flow condition to be solved except for a few weak evidences. This report is a users' manual for the computer programs developed above, describing the structure of program, input data set-up, typical output data and listing.

  15. Bondlines – Online blade measurements (October 2012 and January 2013)

    DEFF Research Database (Denmark)

    McGugan, Malcolm; Chiesura, Gabriele

    Some local deformations in an operating Wind Turbine blade (V80) have been measured during October 2012. Displacement and load values generated between the trailing edge panels at blade radius R9.2m, R10,2m, and R11,2m were obtained. A fluctuating loading of between 100 - 200N existed when the tw...... for the on-site measurements. The data output is then summarised. The full data files will be used to improve models and sub-component testing of these structures, as well as the continuing development of the reinforcement approaches designed to prolong structural life....... edge displacement was re-measured (during January 2013) following a reinforcement of the blade to prevent trailing edge distortion. This trial showed that the new displacement values were below 1mm during similar operating conditions. This report describes the planning for and procurement of hardware...

  16. 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

  17. Artificial Selection Reveals High Genetic Variation in Phenology at the Trailing Edge of a Species Range.

    Science.gov (United States)

    Sheth, Seema Nayan; Angert, Amy Lauren

    2016-02-01

    Species responses to climate change depend on the interplay of migration and adaptation, yet we know relatively little about the potential for adaptation. Genetic adaptations to climate change often involve shifts in the timing of phenological events, such as flowering. If populations at the edge of a species range have lower genetic variation in phenological traits than central populations, then their persistence under climate change could be threatened. To test this hypothesis, we performed artificial selection experiments using the scarlet monkeyflower (Mimulus cardinalis) and compared genetic variation in flowering time among populations at the latitudinal center, northern edge, and southern edge of the species range. We also assessed whether selection on flowering time yielded correlated responses in functional traits, potentially representing a cost associated with early or late flowering. Contrary to prediction, southern populations exhibited greater responses to selection on flowering time than central or northern populations. Further, selection for early flowering resulted in correlated increases in specific leaf area and leaf nitrogen, whereas selection for late flowering led to decreases in these traits. These results provide critical insights about how spatial variation in the potential for adaptation may affect population persistence under changing climates. PMID:26807746

  18. Aeroelastic Analysis of a Flexible Wing Wind Tunnel Model with Variable Camber Continuous Trailing Edge Flap Design

    Science.gov (United States)

    Nguyen, Nhan; Ting, Eric; Lebofsky, Sonia

    2015-01-01

    This paper presents data analysis of a flexible wing wind tunnel model with a variable camber continuous trailing edge flap (VCCTEF) design for drag minimization tested at the University of Washington Aeronautical Laboratory (UWAL). The wind tunnel test was designed to explore the relative merit of the VCCTEF concept for improved cruise efficiency through the use of low-cost aeroelastic model test techniques. The flexible wing model is a 10%-scale model of a typical transport wing and is constructed of woven fabric composites and foam core. The wing structural stiffness in bending is tailored to be half of the stiffness of a Boeing 757-era transport wing while the torsional stiffness is about the same. This stiffness reduction results in a wing tip deflection of about 10% of the wing semi-span. The VCCTEF is a multi-segment flap design having three chordwise camber segments and five spanwise flap sections for a total of 15 individual flap elements. The three chordwise camber segments can be positioned appropriately to create a desired trailing edge camber. Elastomeric material is used to cover the gaps in between the spanwise flap sections, thereby creating a continuous trailing edge. Wind tunnel data analysis conducted previously shows that the VCCTEF can achieve a drag reduction of up to 6.31% and an improvement in the lift-to-drag ratio (L=D) of up to 4.85%. A method for estimating the bending and torsional stiffnesses of the flexible wingUWAL wind tunnel model from static load test data is presented. The resulting estimation indicates that the stiffness of the flexible wing is significantly stiffer in torsion than in bending by as much as 9 to 1. The lift prediction for the flexible wing is computed by a coupled aerodynamic-structural model. The coupled model is developed by coupling a conceptual aerodynamic tool Vorlax with a finite-element model of the flexible wing via an automated geometry deformation tool. Based on the comparison of the lift curve slope

  19. Space environmental effects on LDEF composites: Leading graphite/epoxy panel, selected trailing edge specimens

    Science.gov (United States)

    Dursch, Harry; George, Pete; Hill, Sylvester

    1992-01-01

    The composite electronics-module cover for the leading edge (row D9) experiment M0003-8 was fabricated from T300 graphite/934 epoxy unidirectional prepreg tape in a multi-oriented layup. This panel contained thermal control coatings in three of the four quadrants with the fourth quadrant left uncoated as a control. The composite experienced different thermal cycling extremes in each quadrant due to the differing optical properties of the coatings. Results will be presented on microcracking and other Low Earth Orbital (LEO) effects on the coated panel substrate.

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

    Directory of Open Access Journals (Sweden)

    Kengo Kikuta

    2010-01-01

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

  1. ANALYSIS OF AN ELECTROSTRICTIVE STACK ACTUATOR FOR ACTIVE TRAILING EDGE FLAPS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Stack actuator is a solid-state driving component of Active Tailing Edge Flap in smart rotor systems. It is a multi-layer serial structure of basic units composed of electrostrictive and adhesive layers. In this paper, a dynamic model of the actuator is derived based on the constitutive equation of electrostrictive material and the equation of motion. Theoretical analysis is made on the factors involved in the design of the actuator, which reveals that the electrostrictive layer and the adhesive layer should be optimized to compromise between displacement and frequency requirements. In the final part of the paper, the experiment of an ATEF system is introduced. The results show that the model is reasonable. It also suggests that the bending stiffness of elastic mechanism is an important factor in design, which should be carefully studied to provide satisfactory dynamic response of the ATEF system.

  2. Wicket gate trailing-edge blowing: A method for improving off-design hydroturbine performance by adjusting the runner inlet swirl angle

    International Nuclear Information System (INIS)

    At their best efficiency point (BEP), hydroturbines operate at very high efficiency. However, with the ever-increasing penetration of alternative electricity generation, it has become common to operate hydroturbines at off-design conditions in order to maintain stability in the electric power grid. This paper demonstrates a method for improving hydroturbine performance during off-design operation by injecting water through slots at the trailing edges of the wicket gates. The injected water causes a change in bulk flow direction at the inlet of the runner. This change in flow angle from the wicket gate trailing-edge jets provides the capability of independently varying the flow rate and swirl angle through the runner, which in current designs are both determined by the wicket gate opening angle. When properly tuned, altering the flow angle results in a significant improvement in turbine efficiency during off-design operation

  3. 叶片形状对涡轮桨搅拌槽内尾涡特性的影响%Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines*

    Institute of Scientific and Technical Information of China (English)

    赵静; 高正明; 包雨云

    2011-01-01

    Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their relationship with turbulence properties in a stirred tank of 0.48 m diameter, agitated by four different disc turbines, including Rushton turbine, concaved blade disk turbine, half elliptical blade disk turbine, and parabolic blade disk turbine. Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail. The location, size and strength of vortices were determined by the simplified λ2-criterion and the results showed that the blade shape had great effect on the mailing vortex characteristics. The larger curvature resulted in longer residence time of the vortex at the impeller tip, bigger distance between the upper and lower vortices and longer vortex life, also leads to smaller and stronger vorfces. In addition, the turbulent kinetic energy and turbulent energy dissipation in the discharge flow were determined and discussed. High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them. Although restricted to single phase flow, the presented results are essential for reliable design and scale-up of stirred tank with disc turbines.

  4. Strain Gage Load Calibration of the Wing Interface Fittings for the Adaptive Compliant Trailing Edge Flap Flight Test

    Science.gov (United States)

    Miller, Eric J.; Holguin, Andrew C.; Cruz, Josue; Lokos, William A.

    2014-01-01

    The safety-of-flight parameters for the Adaptive Compliant Trailing Edge (ACTE) flap experiment require that flap-to-wing interface loads be sensed and monitored in real time to ensure that the structural load limits of the wing are not exceeded. This paper discusses the strain gage load calibration testing and load equation derivation methodology for the ACTE interface fittings. Both the left and right wing flap interfaces were monitored; each contained four uniquely designed and instrumented flap interface fittings. The interface hardware design and instrumentation layout are discussed. Twenty-one applied test load cases were developed using the predicted in-flight loads. Pre-test predictions of strain gage responses were produced using finite element method models of the interface fittings. Predicted and measured test strains are presented. A load testing rig and three hydraulic jacks were used to apply combinations of shear, bending, and axial loads to the interface fittings. Hardware deflections under load were measured using photogrammetry and transducers. Due to deflections in the interface fitting hardware and test rig, finite element model techniques were used to calculate the reaction loads throughout the applied load range, taking into account the elastically-deformed geometry. The primary load equations were selected based on multiple calibration metrics. An independent set of validation cases was used to validate each derived equation. The 2-sigma residual errors for the shear loads were less than eight percent of the full-scale calibration load; the 2-sigma residual errors for the bending moment loads were less than three percent of the full-scale calibration load. The derived load equations for shear, bending, and axial loads are presented, with the calculated errors for both the calibration cases and the independent validation load cases.

  5. Metallurgical failure analysis for a blade failed in a gas-turbine engine of a power plant

    International Nuclear Information System (INIS)

    The failed gas-turbine blades (first stage blades) (type Siemens V94.2 KWU) were acquired from TNB Research Sdn. Bhd: a subsidiary of Malaysian power-generation industry (TNB, Malaysia). The blades were sectioned for metallographic investigations. The microstructural characterization involved use of both optical as well as electron microscopes including application of EPMA technique. The Microstructures were compared for three spots selection i.e. leading edge of the blade (transverse and longitudinal), trailing edge of the blade (transverse and longitudinal), and centre (near the platform of the blade) (transverse and longitudinal). The material properties and behavior at high temperature were interpreted on the basis of the observed microstructures and the phases present in the alloy. The interpretations were related to the operating conditions of the turbine blade; and main cause of failure was found to be creep damage. Recommendations have been made for improved material performance.

  6. AERO2S - SUBSONIC AERODYNAMIC ANALYSIS OF WINGS WITH LEADING- AND TRAILING-EDGE FLAPS IN COMBINATION WITH CANARD OR HORIZONTAL TAIL SURFACES (IBM PC VERSION)

    Science.gov (United States)

    Carlson, H. W.

    1994-01-01

    This code was developed to aid design engineers in the selection and evaluation of aerodynamically efficient wing-canard and wing-horizontal-tail configurations that may employ simple hinged-flap systems. Rapid estimates of the longitudinal aerodynamic characteristics of conceptual airplane lifting surface arrangements are provided. The method is particularly well suited to configurations which, because of high speed flight requirements, must employ thin wings with highly swept leading edges. The code is applicable to wings with either sharp or rounded leading edges. The code provides theoretical pressure distributions over the wing, the canard or horizontal tail, and the deflected flap surfaces as well as estimates of the wing lift, drag, and pitching moments which account for attainable leading edge thrust and leading edge separation vortex forces. The wing planform information is specified by a series of leading edge and trailing edge breakpoints for a right hand wing panel. Up to 21 pairs of coordinates may be used to describe both the leading edge and the trailing edge. The code has been written to accommodate 2000 right hand panel elements, but can easily be modified to accommodate a larger or smaller number of elements depending on the capacity of the target computer platform. The code provides solutions for wing surfaces composed of all possible combinations of leading edge and trailing edge flap settings provided by the original deflection multipliers and by the flap deflection multipliers. Up to 25 pairs of leading edge and trailing edge flap deflection schedules may thus be treated simultaneously. The code also provides for an improved accounting of hinge-line singularities in determination of wing forces and moments. To determine lifting surface perturbation velocity distributions, the code provides for a maximum of 70 iterations. The program is constructed so that successive runs may be made with a given code entry. To make additional runs, it is

  7. An experiment study of the serrated trailing edge noise%锯齿型翼型尾缘噪声控制实验研究

    Institute of Scientific and Technical Information of China (English)

    许影博; 李晓东

    2012-01-01

    Trailing edge noise, which is generated by the interaction of turbulence boundary layer and trailing edge, is the dominant component of airfoil self-noise. In last decade, many contributions have been made to the development of the theory, numerical simulation and experiment of the trailing edge noise. However, much effort is still required to advance understanding of the noise generation mechanism and for the suppression strategies. In this paper, some experimental research has been done on suppressing the airfoil noise by serrated trailing edge. The experiments are all carried out in the low-speed open jet wind tunnel, which is in the anechoic chamber. The study is focused on the influence of the angle of attack of the airfoil on the far field noise and the airfoil surface pressure. The far-field measurement shows that the serrated trailing edge is an alternative way to reduce the airfoil noise, especially for the low frequency component. Moreover, it is revealed that the noise reduction is related to the number and the shape of sawtooth. Meanwhile, the surface measurement shows a little change of the surface pressure in the cases with the different serrated trailing edge in present.%翼型湍流边界层与尾缘相互作用产生的尾缘噪声是翼型自噪声的最主要分量,多年来研究者们已经在理论、数值和实验方面开展了多方面研究,但有关翼型尾缘噪声的产生机理和抑制方法仍有待深化与发展.本文利用具有全消声环境的低速开口风洞研究了采用锯齿型翼型尾缘来控制翼型噪声的方法,重点研究了不同攻角情况下不同锯齿形对翼型远声场气动噪声的影响以及翼型表面压力的影响.实验结果表明,翼型尾缘附加锯齿是一种可行的降噪方案,尤其对中低频段的远场气动噪声有比较明显的降低效果;而且,降噪效果与锯齿的齿数和齿间倒角有关.附加锯齿对翼型壁面动态载荷的影响较小,基本不影响翼型的气动性能.

  8. A study of the effects of Reynolds number and Mach number on constant pressure coefficient jump for shock-induced trailing-edge separation

    Science.gov (United States)

    Cunningham, Atlee M., Jr.; Spragle, Gregory S.

    1987-01-01

    The influence of Mach and Reynolds numbers as well as airfoil and planform geometry on the phenomenon of constant shock jump pressure coefficient for conditions of shock induced trailing edge separation (SITES) was studied. It was demonstrated that the phenomenon does exist for a wide variety of two and three dimensional flow cases and that the influence of free stream Mach number was not significant. The influence of Reynolds number was found to be important but was not strong. Airfoil and planform geometric characteristics were found to be very important where the pressure coefficient jump was shown to vary with the sum of: (1) airfoil curvature at the upper surface crest, and (2) camber surface slope at the trailing edge. It was also determined that the onset of SITES could be defined as a function of airfoil geometric parameters and Mach number normal to the leading edge. This onset prediction was shown to predict the angle of onset to within + or - 1 deg accuracy or better for about 90% of the cases studied.

  9. Tomographic and elastic strain characterisation of an additively manufactured turbine blade using bragg-edge neutron spectroscopy

    International Nuclear Information System (INIS)

    Characterisation of the residual strain state within engineering components and materials provides useful information about there deformation and in-service behavior. Non-destructively mapping this strain state however, presents significant challenges. The development of high resolution energy-resolved microchannel plate neutron detectors is enabling new ways to extract material characteristics. A technique known as Bragg-edge neutron transmission has recently been developed as a means to non -destructively evaluate the residual elastic strain state throughout the bulk. The transmission spectrum of thermal neutrons through a polycrystalline material displays a series of well-defined jumps in intensity as a function of incident neutron wavelength, known as Bragg-edges. The positions of these Bragg-edges, provide a two-dimensional map of the average elastic strain in the incident beam direction when compared to the edge position in a ‘strain-free’ reference. By measuring the transmission spectrum for multiple sample orientations, two-dimensional information is built up about the three dimensional strain distribution. However, to recover the three-dimensional strain tensor from these lower order measurements presents significant challenges. Here, we present recent experimental results from the characterisation of a nickel turbine blade fabricated using additive manufacturing. The thermally driven additive processes during manufacture can generate significant strains throughout such components, knowledge of these strains is crucial to the development of the free-form additive building process. We discuss the development of neutron strain tomography as a non-destructive method of efficiently mapping the elastic strain state of whole engineered components at spatial resolutions approaching tens of microns.

  10. Effect of guide wall on jet impingement cooling in blade leading edge channel

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qing-Yang; Chung, Heeyoon; Choi, Seok Min; Cho, Hyung Hee [Yonsei University, Seoul (Korea, Republic of)

    2016-02-15

    The characteristics of fluid flow and heat transfer, which are affected by the guide wall in a jet impinged leading edge channel, have been investigated numerically using three-dimensional Reynolds-averaged Navier-Stokes analysis via the shear stress transport turbulence model and gamma theta transitional turbulence model. A constant wall heat flux condition has been applied to the leading edge surface. The jet-to-surface distance is constant, which is three times that of the jet diameter. The arrangement of the guide wall near the jet hole is set as a variable. Results presented in this study include the Nusselt number contour, velocity vector, streamline with velocity, and local Nusselt number distribution along the central line on the leading edge surface. The average Nusselt number and average pressure loss between jet nozzle and channel exit are calculated to assess the thermal performance. The application of the guide wall is aimed at improving heat transfer uniformity on the leading edge surface. Results indicated that the streamwise guide wall ensures the vertical jet impingement flow intensity and prevents the flow after impingement to reflux into jet flow. Thus, a combined rectangular guide wall benefits the average heat transfer, thermal performance and heat transfer distribution uniformity.

  11. The Snowmastodon Project: cutting-edge science on the blade of a bulldozer

    Science.gov (United States)

    Pigati, Jeffery S.; Miller, Ian M.; Johnson, Kirk R.

    2015-01-01

    Cutting-edge science happens at a variety of scales, from the individual and intimate to the large-scale and collaborative. The publication of a special issue of Quaternary Research in Nov. 2014 dedicated to the scientific findings of the “Snowmastodon Project” highlights what can be done when natural history museums, governmental agencies, and academic institutions work toward a common goal.

  12. A comparative analysis of 3D flow fields between straight and bowed blades in a steam turbine

    Institute of Scientific and Technical Information of China (English)

    M.HASSANVAND; WANG Zhong-qi 王仲奇; WANG Song-tao 王松涛

    2004-01-01

    A commercial Navier-Stokes flow solver has been employed tor simulating steady subsonic flow characteristics and analyzing the comparative features of flow fields between straight and bowed blades applied to the stator of a high pressure steam turbine. For comparison, we have studied the effects of bowed blades on the wakes of stator trailing edge and horse shoe vortex in the rotor. It was found that the position of wakes for bowed blades is shifted toward the blade suction side. Also, we have discussed and compared the entropy generation and energy loss caused by dissipation mechanism within the boundary layers on the hub and shroud; and temperature gradient in meridional plane.

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

    Science.gov (United States)

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

    1982-01-01

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

  14. A low speed wind tunnel investigation of Reynolds number effects on a 60-deg swept wing configuration with leading and trailing edge flaps

    Science.gov (United States)

    Rao, Dhanvada M.; Hoffler, Keith D.

    1988-01-01

    A low-speed wind tunnel test was performed to investigate Reynolds number effects on the aerodynamic characteristics of a supersonic cruise wing concept model with a 60-deg swept wing incorporating leading-edge and trailing-edge flap deflections. The Reynolds number ranged from 0.3 to 1.6 x 10 to the 6th, and corresponding Mach numbers from .05 to 0.3. The objective was to define a threshold Reynolds number above which the flap aerodynamics basically remained unchanged, and also to generate a data base useful for validating theoretical predictions for the Reynolds number effects on flap performance. This report documents the test procedures used and the basic data acquired in the investigation.

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

    Directory of Open Access Journals (Sweden)

    Navneet Kumar

    2016-06-01

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

  16. 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...

  17. EWSHM 2014: Operational Modal Analysis and Wavelet Transformation for Damage Identification in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Tcherniak, Dmitri; Kirkegaard, Poul Henning;

    2016-01-01

    The presented study demonstrates an application of a previously proposed modal and wavelet analysis-based damage identification method to a wind turbine blade. A trailing edge debonding was introduced to a SSP 34 m blade mounted on a test rig. Operational modal analysis (OMA) was conducted to...... obtain mode shapes for undamaged and damaged states of the blade. Subsequently, the mode shapes were analyzed with one-dimensional continuous wavelet transformations (CWTs) for damage identification. The basic idea of the method is that structural damage will introduce local mode shape irregularities...

  18. Operational modal analysis and wavelet transformation for damage identification in wind turbine blades

    DEFF Research Database (Denmark)

    Ulriksen, Martin Dalgaard; Tcherniak, Dmitri; Kirkegaard, Poul Henning;

    2014-01-01

    The presented study demonstrates an application of a previously proposed modal and wavelet analysis-based damage identification method to a wind turbine blade. A trailing edge debonding was introduced to a SSP 34m blade mounted on a test rig. Operational modal analysis (OMA) was conducted to obtain...... mode shapes for undamaged and damaged states of the blade. Subsequently, the mode shapes were analyzed with one-dimensional continuous wavelet transformations (CWTs) for damage identification. The basic idea of the method is that structural damage will introduce local mode shape irregularities which...

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

    Directory of Open Access Journals (Sweden)

    Velissarios Kourkoulis

    2013-07-01

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

  20. Micro-abrasion package capture cell experiment on the trailing edge of LDEF: Impactor chemistry and whipple bumper shield efficiencies

    Science.gov (United States)

    Fitzgerald, Howard J.; Yano, Hajime

    1995-01-01

    Four of the eight available double layer microparticle capture cells, flown as the experiment A0023 on the trailing (West) face of LDEF, have been extensively studied. An investigation of the chemistry of impactors has been made using SEM/EDX techniques and the effectiveness of the capture cells as bumper shields has also been examined. Studies of these capture cells gave positive EDX results, with 53 percent of impact sites indicating the presence of some chemical residues, the predominant residue identified as being silicon in varying quantities.

  1. Studies on estimating the performance of impellers with cut-down of the blade edge of the centrifugal pump by the surface singularity method

    Science.gov (United States)

    Furukawa, Akinori; Cheng, Ci-Chang; Takamatsu, Yasuo

    1990-08-01

    Pump performance depends on the outlet flow of the impeller. A method of surface singularities for core flow in the centrifugal impeller, combined with an integral method for a boundary layer, would explain the mechanism of the performance change caused by cutting the outlet edge of the impeller blades down. This method is applied to flows in the impellers with various cut-downs of the blade edge, and then the calculated results are compared with the experimental ones. Both results are shown to be quantitatively in good agreement. On the influence of cutting the blade edge on the outlet flow, it is indicated that the cut of the pressure surface results in the decrease of relative flow angle with the decrease of radial velocity in the core flow, while that of the suction surface results only in a decrease in radial velocity. The change in the flow separation region due to the cut on the suction surface, however, contributes to the deterioration of pump performance.

  2. Lightning protection of flap system for wind turbine blades

    DEFF Research Database (Denmark)

    Candela Garolera, Anna; Madsen, Søren Find

    The aim of this PhD project was to investigate the behaviour of a Controllable Rubber Trailing Edge Flap (CRTEF) in a wind turbine blade when it is exposed to lightning discharges, and find the best technical solution to protect the CRTEF and the controlling system against lightning, based on the...... results of simulation models and high voltage tests. Wind turbines are a common target of lightning due to their height and location, and blades are the components most exposed to direct discharges. Protecting the blades against lightning is specially challenging, mainly because of the combination of...... insulating, semi-conductive and conductive materials in their structure. For this reason, the installation of a CRTEF in a blade requires a careful assessment of risks related to lightning strikes. The study of the lightning effects in the CRTEF system comprised the analysis of the discharge attachment, the...

  3. Design optimization for active twist rotor blades

    Science.gov (United States)

    Mok, Ji Won

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

  4. Effect of RANS-Type Turbulence Models on Adiabatic Film Cooling Effectiveness over a Scaled Up Gas Turbine Blade Leading Edge Surface

    Science.gov (United States)

    Yepuri, Giridhara Babu; Talanki Puttarangasetty, Ashok Babu; Kolke, Deepak Kumar; Jesuraj, Felix

    2016-06-01

    Increasing the gas turbine inlet temperature is one of the key technologies in raising gas turbine engine power output. Film cooling is one of the efficient cooling techniques to cool the hot section components of a gas turbine engines in turn the turbine inlet temperature can be increased. This study aims at investigating the effect of RANS-type turbulence models on adiabatic film cooling effectiveness over a scaled up gas turbine blade leading edge surfaces. For the evaluation, five different two equation RANS-type turbulent models have been taken in consideration, which are available in the ANSYS-Fluent. For this analysis, the gas turbine blade leading edge configuration is generated using Solid Works. The meshing is done using ANSYS-Workbench Mesh and ANSYS-Fluent is used as a solver to solve the flow field. The considered gas turbine blade leading edge model is having five rows of film cooling circular holes, one at stagnation line and the two each on either side of stagnation line at 30° and 60° respectively. Each row has the five holes with the hole diameter of 4 mm, pitch of 21 mm arranged in staggered manner and has the hole injection angle of 30° in span wise direction. The experiments are carried in a subsonic cascade tunnel facility at heat transfer lab of CSIR-National Aerospace Laboratory with a Reynolds number of 1,00,000 based on leading edge diameter. From the Computational Fluid Dynamics (CFD) evaluation it is found that K-ɛ Realizable model gives more acceptable results with the experimental values, compared to the other considered turbulence models for this type of geometries. Further the CFD evaluated results, using K-ɛ Realizable model at different blowing ratios are compared with the experimental results.

  5. Simulation of unsteady flows through stator and rotor blades of a gas turbine using the Chimera method

    Science.gov (United States)

    Nakamura, S.; Scott, J. N.

    1993-01-01

    A two-dimensional model to solve compressible Navier-Stokes equations for the flow through stator and rotor blades of a turbine is developed. The flow domains for the stator and rotor blades are coupled by the Chimera method that makes grid generation easy and enhances accuracy because the area of the grid that have high turning of grid lines or high skewness can be eliminated from the computational domain after the grids are generated. The results of flow computations show various important features of unsteady flows including the acoustic waves interacting with boundary layers, Karman vortex shedding from the trailing edge of the stator blades, pulsating incoming flow to a rotor blade from passing stator blades, and flow separation from both suction and pressure sides of the rotor blades.

  6. 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

  7. Effect of a Damage to Modal Parameters of a Wind Turbine Blade

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.; Berring, Peter; Tcherniak, Dmitri;

    2014-01-01

    This study reports structural dynamic characteristics obtained experimentally from an extensive testing campaign on a 34m long wind turbine blade mounted on a test-rig under laboratory conditions. Further, these experimental results have been compared with analog numerical results obtained from a...... mode shapes - especially if decomposed into the flapwise, edgewise and torsional components - contain information which might be helpful for detecting and localizing wind turbine blade damages....... very detailed FE model of the same blade using 3D solid elements. Both an undamaged and a damaged blade are investigated, and it is observed that the natural frequencies of the first few modes of the blade change very little due to a significant artificial damage imposed in trailing edge, whereas the...

  8. 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.

  9. 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.

  10. The heat transfer analysis of the first stage blade

    International Nuclear Information System (INIS)

    To get higher efficiency of gas turbine, the designer should have more higher Turbine Inlet Temperature(TIT). Today, modern gas turbine having sophisticated cooling scheme has TIT above 1,700 .deg. C. In the Korea, many gas turbine having TIT above 1,300 .deg. C was imported and being operated, but the gas with high TIT above 1,300 .deg. C in the turbine will give damage to liner of combustor, and blade of turbine and etc. So frequently maintenance for parts enduring high temperature was performed. In this study, the heat transfer analysis of cooling air in the internal cooling channel (network analysis) and temperature analysis of the blade (Finite Element Analysis) in the first stage rotor was conducted for development of the optimal cooling passage design procedure. The results of network analysis and FEM analysis of blade show that the high temperature spot are occurred at the leading edge, trailing edge near tip, and platform. So to get more reliable performance of gas turbine, the more efficient cooling method should be applied at the leading edge and tip section and the thermal barrier coating on the blade surface has important role in cooling blade

  11. Wide bandsaw blade under cutting conditions. Part I: Vibration of a plate moving in its plane while subjected to tangential edge loading

    Science.gov (United States)

    Lengoc, L.; McCallion, H.

    1995-09-01

    The cutting span of a bandsaw blade is modelled as a moving plate and a simple, yet powerful, method is presented for analyzing its vibration when subjected to various in-plane stresses, including stresses due to tangential cutting forces. Time-independent tangential edge-loading couples modes of vibration and can lead to divergent buckling. The effects of transport velocity, "back-crowning" and "prestressing" on the vibration of a moving plate under tangential cutting forces are also investigated. Graphical representations of the modes of vibration are presented.

  12. Automated eddy current inspection of Space Shuttle APU turbine wheel blades

    Science.gov (United States)

    Fisher, Jay L.; Rowland, Stephen N.; Stolte, Jeffrey S.; Salkowski, Charles

    1991-01-01

    An automated inspection system based on eddy current testing (ET) techniques has been developed to inspect turbine wheel blades on the APU used in NASA's Space Transportation system. The APU is a hydrazine-powered gas turbine with a 15-cm diameter Rene 41 turbine wheel, which has 123 first-stage blades and 123 second-stage blades. The flaw detection capability of the ET system is verified through comparison with fluorescent penetrant test results. Results of the comparison indicate that ET is capable of inspecting surfaces with very restrictive geometries. The ET capability requires development of probes with extremely small coils to allow inspection within 0.4 mm of the blade root and the leading and trailing edges of the blade and within a height restriction of less than 1 mm. The color 2D presentation of the ET data provided crack-growth pattern and length information similar to those found with visual techniques. It also provided visual clues to minimize geometry effects such as generated from blade edges, a neighoring blade, and changes in the blade thickness.

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

    Science.gov (United States)

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

    1983-01-01

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

  14. 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.

  15. 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. .

  16. 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.

  17. Initial Assessment of a Variable-Camber Continuous Trailing-Edge Flap System on a Rigid Wing for Drag Reduction in Subsonic Cruise

    Science.gov (United States)

    Ippolito, Corey; Nguyen, Nhan; Totah, Joe; Trinh, Khanh; Ting, Eric

    2013-01-01

    In this paper, we describe an initial optimization study of a Variable-Camber Continuous Trailing-Edge Flap (VCCTEF) system. The VCCTEF provides a light-weight control system for aircraft with long flexible wings, providing efficient high-lift capability for takeoff and landing, and greater efficiency with reduced drag at cruising flight by considering the effects of aeroelastic wing deformations in the control law. The VCCTEF system is comprised of a large number of distributed and individually-actuatable control surfaces that are constrained in movement relative to neighboring surfaces, and are non-trivially coupled through structural aeroelastic dynamics. Minimzation of drag results in a constrained, coupled, non-linear optimization over a high-dimension search space. In this paper, we describe the modeling, analysis, and optimization of the VCCTEF system control inputs for minimum drag in cruise. The purpose of this initial study is to quantify the expected benefits of the system concept. The scope of this analysis is limited to consideration of a rigid wing without structural flexibility in a steady-state cruise condition at various fuel weights. For analysis, we developed an optimization engine that couples geometric synthesis with vortex-lattice analysis to automate the optimization procedure. In this paper, we present and describe the VCCTEF system concept, optimization approach and tools, run-time performance, and results of the optimization at 20%, 50%, and 80% fuel load. This initial limited-scope study finds the VCCTEF system can potentially gain nearly 10% reduction in cruise drag, provides greater drag savings at lower operating weight, and efficiency is negatively impacted by the severity of relative constraints between control surfaces.

  18. Development of high-rate large-deflection hingeless trailing-edge control surface for the Smart Wing wind tunnel model

    Science.gov (United States)

    Wang, Donny P.; Bartley-Cho, Jonathan D.; Martin, Christopher A.; Hallam, Brian J.

    2001-06-01

    A key objective of the Smart Wing Phase 2, Test 2 is to demonstrate high-rate actuation of hingeless control surfaces using smart material-based actuators. Actuation rates resulting in a minimum of 20 degree(s) flap deflection in 0.33 sec, producing a sweep rate of at least 60 degree(s)/sec, are desired. This sweep rate is similar to those specified for many of the existing military platforms with hinged control surfaces. The ability to deploy control surfaces without discrete hingeline would, however, enhance platform mission by reducing radar cross section and improving aerodynamic performance. Studies on numerous actuation concepts and flexible structures were executed during the early and mid phase of the program in an effort to satisfy these goals. In the first study, several actuation concepts with different transducers were modeled and analyzed. These concepts included distributed piezoelectric stack actuators with and without hydraulic amplifiers and pumps, antagonistic tendon actuation, and eccentuation. The transducers selected for the trade studies included piezoelectric ultrasonic motors, actively cooled SMA, ferromagnetic SMA, and stacks made from piezoelectric ceramic wafer, piezoelectric single crystal wafer, irradiated PVDF-TrFE film, and dielectric elastomer film. Although many of the technologies are not fully mature, they provide a glimpse of what improvements could be possible with their successful development. The studies showed that distributed polymer stacks provided the most elegant solution, but eccentuation was deemed the most realistic and lowest risk approach to attaining the program goals. A common issue to all the concepts was the structural stiffness that the actuators worked against. This was resolved in the second study by developing a flexcore- elastomeric skin trailing edge structure with eccentuation using high power ultrasonic motors. This paper describes the two studies and the final concept in detail.

  19. Improved Trailing Edge Noise Model

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    The modeling of the surface pressure spectrum under a turbulent boundary layer is investigated in the presence of an adverse pressure gradient along the flow direction. It is shown that discrepancies between measurements and results from a well-known model increase as the pressure gradient increa...

  20. Application of holography to flow visualization within rotating compressor blade row. [to determine three dimensional shock patterns

    Science.gov (United States)

    Wuerker, R. F.; Kobayashi, R. J.; Heflinger, L. O.; Ware, T. C.

    1974-01-01

    Two holographic interblade row flow visualization systems were designed to determine the three-dimensional shock patterns and velocity distributions within the rotating blade row of a transonic fan rotor, utilizing the techniques of pulsed laser transmission holography. Both single- and double-exposure bright field holograms and dark field scattered-light holograms were successfully recorded. Two plastic windows were installed in the rotor tip casing and outer casing forward of the rotor to view the rotor blade passage. The viewing angle allowed detailed investigation of the leading edge shocks and shocks in the midspan damper area; limited details of the trailing edge shocks also were visible. A technique was devised for interpreting the reconstructed holograms by constructing three dimensional models that allowed identification of the major shock systems. The models compared favorably with theoretical predictions and results of the overall and blade element data. Most of the holograms were made using the rapid double-pulse technique.

  1. 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.

  2. Heat Transfer and Flow on the Squealer Tip of a Gas Turbine Blade

    Science.gov (United States)

    Azad, Gm S.; Han, Je-Chin; Boyle, Robert J.

    2000-01-01

    Experimental investigations are performed to measure the detailed heat transfer coefficient and static pressure distributions on the squealer tip of a gas turbine blade in a five-bladed stationary linear cascade. The blade is a 2-dimensional model of a modem first stage gas turbine rotor blade with a blade tip profile of a GE-E(sup 3) aircraft gas turbine engine rotor blade. A squealer (recessed) tip with a 3.77% recess is considered here. The data on the squealer tip are also compared with a flat tip case. All measurements are made at three different tip gap clearances of about 1%, 1.5%, and 2.5% of the blade span. Two different turbulence intensities of 6.1% and 9.7% at the cascade inlet are also considered for heat transfer measurements. Static pressure measurements are made in the mid-span and near-tip regions, as well as on the shroud surface opposite to the blade tip surface. The flow condition in the test cascade corresponds to an overall pressure ratio of 1.32 and an exit Reynolds number based on the axial chord of 1.1 x 10(exp 6). A transient liquid crystal technique is used to measure the heat transfer coefficients. Results show that the heat transfer coefficient on the cavity surface and rim increases with an increase in tip clearance. 'Me heat transfer coefficient on the rim is higher than the cavity surface. The cavity surface has a higher heat transfer coefficient near the leading edge region than the trailing edge region. The heat transfer coefficient on the pressure side rim and trailing edge region is higher at a higher turbulence intensity level of 9.7% over 6.1 % case. However, no significant difference in local heat transfer coefficient is observed inside the cavity and the suction side rim for the two turbulence intensities. The squealer tip blade provides a lower overall heat transfer coefficient when compared to the flat tip blade.

  3. Compressor leading edges

    OpenAIRE

    Goodhand, Martin

    2011-01-01

    Compressor blades often have a small 'spike' in the surface pressure distribution at the leading edge. This may result from blade erosion, manufacture defects or compromises made in the original design process. In this thesis it is shown that these spikes will increase the loss generated by a blade only when they become large enough to initiate boundary layer transition at the leading edge through a separation bubble; this process increases profile loss by about 30%. A criterion is presen...

  4. 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.

  5. Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

    Science.gov (United States)

    Ji, Yongbin; Ma, Chao; Ge, Bing; Zang, Shusheng

    2016-08-01

    A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

  6. Influence of turbine blade geometry on thickness of TBCs deposited by VPA and PS-PVD methods

    Directory of Open Access Journals (Sweden)

    M. Góral

    2012-03-01

    Full Text Available Purpose: The authors presented in the article the influence of the jet engine turbine blade profile on the thickness and microstructure of thermal barrier coatings.Design/methodology/approach: The assessment of model blade made of ZS6K alloy used in the first stage of the turbine engine was performed. The diffusion aluminide coating as well as the thermal barrier coating were deposited on the blade surface with a use of the out of pack method. The zirconia stabilized by yttrium oxide coating was deposited by PS-PVD method The research was performed with a use of light- and scanning microscopy.Findings: It has been proven, that the thickest coating was found on the leading edge and trailing edge of the blade. In those places the coating thickness was approx. 20-30% larger than in the other areas on turbine blade.Research limitations/implications: The research was performed with a use of light- and scanning microscopy.Practical implications: The obtained results indicate that it is possible to create the thermal barrier coating by PS-PVD process on the first stage turbine blades of the aircraft engine. It indicates the possibility of application of this process in the industrial practice.Originality/value: The new method for TBC coating production were used.

  7. 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.

  8. Design and testing of a deformable wind turbine blade control surface

    International Nuclear Information System (INIS)

    Wind tunnel tests were conducted on a 1.3 m chord NACA 63–418 blade section fitted with an adaptive trailing edge flap. The 20% chord flap had an aramid honeycomb core covered with a silicone skin and was actuated using servo motors. The honeycomb core had a high stiffness in the thickness direction but was compliant in chordwise bending. These anisotropic properties offer a potential solution for the conflicting design requirements found in morphing trailing edge structures. Static and dynamic tests were performed up to a Reynolds number of 5.4 × 106. The tests showed that deflecting the flap from − 10° to + 10° changes the blade section lift coefficient by 1.0 in non-stalled conditions. Dynamic tests showed the flap to be capable of operating up to 9° s−1 using a 15 V power supply. A two-dimensional static aeroelastic model of the morphing flap was developed to analyse strains, predict actuator requirements and study fluid–structure interaction effects. The model was used to conduct parametric studies to further improve the flap design. Potential applications include wind turbine blade load alleviation and increased wind energy capture. (paper)

  9. Superior Hiking Trail

    Data.gov (United States)

    Minnesota Department of Natural Resources — Superior Hiking Trail main trail, spurs, and camp spurs for completed trail throughout Cook, Lake, St. Louis and Carlton counties. These data were collected with...

  10. Superior Hiking Trail Facilities

    Data.gov (United States)

    Minnesota Department of Natural Resources — Superior Hiking Trail main trail, spurs, and camp spurs for completed trail throughout Cook, Lake, St. Louis and Carlton counties. These data were collected with...

  11. Experiments on sound radiation from propeller blades

    Science.gov (United States)

    Verhulst, K.; Debruijn, A.

    1981-08-01

    The effect of blade damping and air bubbles on cavitation noise radiation, and the damping effect of an antisinging edge were studied. Completely flat cunial and aluminum blades were used. One cunial blade had a viscoelastic sandwich layer. Cavitation was simulated by steam injection. The antisinging edge and viscoelastic layer have little effect. Aluminum reduces total sound power. When the distance of the bubble screen to the steam injection source is less than half a wavelength, radiated sound power is greatly reduced.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-04-01

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

  13. 基于鸟翼后缘的仿生翼型的阻力数值模拟%Aerodynamic Performance of Bionic Foils based on Trailing Edge of Pigeon

    Institute of Scientific and Technical Information of China (English)

    陈衡; 林晓华; 成卓; 王庆五

    2011-01-01

    基于对流体介质中典型动物信鸽减阻功能的研究,揭示了其低阻力翼羽独有的序贯排列方式;量化了信鸽翅膀翼羽后缘形态特征几何信息,并建立仿生模型,其展向后缘形态可以用波长与振幅(波峰、波谷)来限定。对仿生翼型模型的气动特性进行了数值模拟。结果表明,仿生翼型结构能够改善翼型的气动性能,阻力减幅高达9.1%。%The features of drag reduction of the representative pigeon in fluid medium were studied. It was found that the flight capability of the pigeon mainly depends upon the distinct sequential array of its high lift wing feathers. Quantify the geometric information about the leading edge shape of the pigeon wing, bionic models were built in which the trailing edge shape was defined by wavelength and wavecrest to wavetrough amplitude. The finite volume method and the pressure corrected SIMPLEC algorithm were used to simulate numerically the aerodynamic performance of the bionic airfoil model. The results show that at the condition of deep stall, the bionic airfoil model can improve significantly the aeroperformance, reduce aerodynamic drag by 9.1%.

  14. Hot isostatic pressing process to rejuvenate serviced cast nickel base superalloy IN738 turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Wangyao, P. [Chulalongkorn Univ., Bangkok (TH). Metallurgy and Materials Science Research Institute (MMRI); Zrnik, J. [Technical Univ. of Kosice (Czech Republic). Dept. of Materials Science; Polsilapa, S. [Kasetsart Univ., Bangkok (Thailand). Dept. of Materials Engineering, Engineering Faculty; Nisaratanaporn, E. [Chulalongkorn Univ., Bangkok (Thailand). Dept. of Metallurgy Engineering, Engineering Faculty; Homkrajai, W. [Electricity Generating Authority of Thailand (EGAT), Nonthaburi (Thailand)

    2006-07-01

    Many of land base gas turbines for power plants are already long-time operating and lots of efforts were brought to evaluate the remnant life of turbine components. The aims is to assess the actual conditions of the material used for critical components are sustainable with respect to remaining life judgement. The present work provides information on land-base gas turbine first-stage turbine blade structure degradation due to long-term thermomechanical and environmental exposure. The virgin blade was of cast and heat treated nickel base superalloy IN 738 and prior examination it was exposed more than 70 000 hours at turbine inlet temperature, operating by Electricity Generating Authority of Thailand (EGAT) company. The pieces, differently localized along the blade, were cut off for microstructural analyses, which were performed using light and scanning electron microscopy. After long-term service the gamma prime coarsening, re-precipitation of finer gamma prime precipitates and grain boundary carbide precipitates dissolving were observed. The most degraded microstructure was found at top part of trailing edge and at the middle leading edge of blade where small cracks, pores and nests of voids were observed. In order to find proper condition to recover the microstructure the attempt of rejuvenation involving hot isostatic pressing (HIP) followed by standard heat treatment of IN 738 alloy was employed to pieces of the blade. The series of HIP treatments at two different temperatures and at different holds have been conducted. This process appeared to be successful in healing of micro voids and pores in interior of blade, but no restoration of surface defects was observed. Increasing the HIP temperature and extending the HIP time higher efficiency for micro voids and porosity closing were observed. (orig.)

  15. Numerical study of a bio-centrifugal blood pump with straight impeller blade profiles.

    Science.gov (United States)

    Song, Guoliang; Chua, Leok Poh; Lim, Tau Meng

    2010-02-01

    Computational fluid dynamic simulations of the flow in the Kyoto-NTN (Kyoto University, Kyoto, Japan) magnetically suspended centrifugal blood pump with a 16-straight-bladed impeller were performed in the present study. The flow in the pump was assumed as unsteady and turbulent, and blood was treated as a Newtonian fluid. At the impeller rotating speed of 2000 rpm and flow rate of 5 L/min, the pump produces a pressure head of 113.5 mm Hg according to the simulation. It was found that the double volute of the pump has caused symmetrical pressure distribution in the volute passages and subsequently caused symmetrical flow patterns in the blade channels. Due to the tangentially increasing pressure in the volute passages, the flow through the blade channels initially increases at the low-pressure region and then decreases due to the increased pressure. The reverse flow and vortices have been identified in the impeller blade channels. The high shear stress of the flow in the pump mainly occurred at the inlet and outlet of the blade channels, the beginning of the volute passages and the regions around the tips of the cutwater and splitter plate. Higher shear stress is obtained when the tips of the cutwater and splitter plate are located at the impeller blade trailing edges than when they are located at the middle of the impeller blade channel. It was found that the blood damage index assessed based on the blood corpuscle path tracing of the present pump was about 0.94%, which has the same order of magnitude as those of the clinical centrifugal pumps reported in the literature. PMID:19817732

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

    Science.gov (United States)

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

    2013-05-01

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

  17. 基于正交设计的风力机翼型尾缘襟翼参数分析%Parameter Analysis on Wind Turbine Airfoil With Trailing Edge Flap Based on Orthogonal Design Method

    Institute of Scientific and Technical Information of China (English)

    李传峰; 徐宇; 宋娟娟; 赵晓路; 徐建中

    2012-01-01

    引入试验中正交设计的思想,通过数值模拟研究了风力机翼型尾缘襟翼不同参数的影响。采用带有转捩模型的SSTk—u湍流模型模拟了基于S809的尾缘襟翼的尺寸、偏斜角度和形状的影响。结果表明:尾缘襟翼尺寸、偏斜角度对于翼型相关气动参数影响较大,在考查参数范围内折中采用10%弦长、偏斜10°的尾缘襟翼综合性能较好;尾缘襟翼形状函数影响相对较小,采用变化较平缓的尾缘襟翼有利于保持流动稳定性。%Introducing the orthogonal experimental design method, influences of different parameters such as the size, angle and shape, on the wind turbine airfoil S809 with a trailing edge flap are studied using SST k - w turbulence model with a transition model. The results indicate that the flap size and angle have big influences on aerodynamic properties of wind turbine airfoil. Among the studied parameters, the flap with 10% chord length and 10° flap angle obtains better performances. The shape of the flap has relatively smaller influences, but it makes for a stable flowfield using a mildly changing flap shape.

  18. Surface integrity of GH4169 affected by cantilever finish grinding and the application in aero-engine blades

    Directory of Open Access Journals (Sweden)

    Li Xun

    2015-10-01

    Full Text Available GH4169 is the main material for aero-engine blades and integrated blisks. Because GH4169 has a poor milling performance, the profile precision and surface integrity of blades and integrated blisks are difficult to be met by utilizing the conventional milling process, which directly influence the global performance and reliability of aero-engines. Through grinding experiments on parameters and surface integrity optimization, the helical cantilever grinding process utilizing a 300# CBN RB wheel is presented and applied in finish machining of GH4169 blades. The profile errors of the blade surface are within ±0.01 mm, the roughness is less than 0.4 μm, the residual compressive stresses and the hardening rate are appropriate, there are no phenomena of burr and smearing with the grinding chips, and the leading/trailing edge can be smoothly connected with the suction/pressure surface. All the experimental results indicate that this grinding process is greatly suitable for the profile finish machining of GH4169 blades.

  19. Surface integrity of GH4169 affected by cantilever finish grinding and the application in aero-engine blades

    Institute of Scientific and Technical Information of China (English)

    Li Xun; Ma Shuang; Meng Fanjun

    2015-01-01

    GH4169 is the main material for aero-engine blades and integrated blisks. Because GH4169 has a poor milling performance, the profile precision and surface integrity of blades and integrated blisks are difficult to be met by utilizing the conventional milling process, which directly influence the global performance and reliability of aero-engines. Through grinding experiments on parameters and surface integrity optimization, the helical cantilever grinding process utilizing a 300# CBN RB wheel is presented and applied in finish machining of GH4169 blades. The profile errors of the blade surface are within ±0.01 mm, the roughness is less than 0.4 lm, the residual compressive stresses and the hardening rate are appropriate, there are no phenomena of burr and smearing with the grinding chips, and the leading/trailing edge can be smoothly connected with the suction/pressure surface. All the experimental results indicate that this grinding process is greatly suitable for the profile finish machining of GH4169 blades.

  20. 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.

  1. Analysis of wind turbine blade behavior under static dual axis loads

    Energy Technology Data Exchange (ETDEWEB)

    Son, Byung Jik [Korea Univ., Seoul (Korea, Republic of); Huh, Yong Hak; Kim, Dong Jin; Kim, Jong Il [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2012-03-15

    For the assessment of the performance of a wind turbine blade, a simulated loading test may be required. In this study, the blade behavior was investigated through numerical analysis using a dual axis loading test, closely simulating the real operation conditions. The blade structure for the 100 kw class wind turbine system was modeled using the finite element (FE) program ANSYS. The failure criteria and buckling analysis under dual axis loading were examined. The failure analysis, including fiber failure and inter fiber failure, was performed with Puck's failure criterion. As the dual axis load ratio increases, the relatively increased stress occurs at the trailing edge and skin surface 3300-3600mm away from the root. Furthermore, it is revealed that increasing the dual axis load ratio makes the location that is weakest against buckling move toward the root part. Thus, it is seen that the dual axis load test may be an essential requirement for the verification of blade performance.

  2. Individual blade pitch and camber control for vertical axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bhatta, P.; Paluszek, M.A.; Mueller, J.B. [Princeton Satellite Systems, Inc., Princeton, NJ (United States)

    2008-07-01

    This paper presented advanced technology concepts that can enhance the efficiency of a vertical axis wind turbine (VAWT) designed for the domestic market, including regions without favourable wind conditions. Improvements in efficiency can be achieved in many ways, including individual blade actuation; power electronics control for maximum power point tracking; model-based control algorithms; state and parameters estimation; and high efficiency power converters. This paper focused on power extraction improvements by using simple pitch control. It also presented a dynamical systems model and control algorithms for a small, vertical axis wind turbine (VAWT). Good performance at low wind speeds is an important requirement for developing an economically viable, suburban VAWT. The performance of a VAWT can be improved significantly by incorporating estimation and control capabilities. Individual blade pitch and camber controls were considered in the author's VAWT design. Pitch control was achieved by rotating each individual blade about its vertical axis, while camber control was realized using a trailing edge flap on each blade. Using camber and pitch controls helped create a greater force differential across the turbine than using pitch control alone. 8 refs., 9 figs.

  3. Minnesota State Trails

    Data.gov (United States)

    Minnesota Department of Natural Resources — State trails maintained by Minnesota DNR Division of Parks and Trails. These have multiple use status with specific activities supported in designated sections....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-15

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

  5. Effects of diffuser blade geometry at leading edge on a highly-loaded centrifugal compressor%高负荷离心压气机扩压器叶片前缘结构分析

    Institute of Scientific and Technical Information of China (English)

    王毅; 卢新根; 赵胜丰; 朱俊强

    2011-01-01

    为拓宽离心压气机稳定工作范围,以某高负荷离心压气机为研究对象,对径向扩压器叶片前缘进行盘侧开槽处理,借助数值模拟手段,探讨了开槽处理对离心压气机性能和稳定工作范围的影响,并对开槽结构进行了参数化研究,确定了主要开槽参数对离心压气机的影响.数值计算表明,径向扩压器前缘盘侧开槽能够在一定程度上提高离心压气机的稳定工作裕度,但同时伴随着压气机性能的降低.详细对比分析了开槽结构引人前后离心压气机内部流场结构,揭示了径向扩压器叶片前缘开槽提高离心压气机稳定工作裕度机理.%To extend the stable operating range of centrifugal compressor, a series of numerical simulations were performed for a highly - loaded centrifugal compressor with slotted radial diffuser blade at the bottom of leading edge, and the effects of slotted radial diffuser blade on performance and stable operating range of the centrifugal compressor were investigated in detail. In addition, parametric studies on slot depth and slot width were conducted in order to explore the key role parameters for optimum performance. The simulation results indicate that slotted radial diffuser blade at leading edge could extend the stable operating range, but slightly decrease the pressure ratio and efficiency. Detailed analysis of the flow visualization has exposed the different tip flow topologies between the cases with original radial diffuser and slotted radial diffuser, therefore led to some preliminary conclusions as to the flow physics involved in the stall margin improvements afforded by the use of slotted radial diffuser.

  6. 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.

  7. Cyclic Structural Analyses of SSME Turbine Blades

    Science.gov (United States)

    Kaufman, A.; Manderscheid, J. M.

    1985-01-01

    The problems of calculating the structural response of high-temperature space propulsion components such as turbine blades for the fuel turbopump are addressed. The first high-pressure-stage fuel turbine blade (HPFTB) in the liquid-hydrogen turbopump of the space shuttle main engine (SSME) was selected for this study. In the past these blades have cracked in the blade shank region and at the airfoil leading edge adjacent to the platform. To achieve the necessary durability, these blades are currently being cast by using directional solidification. Single-crystal alloys are also being investigated for future SSME applications. The study evaluated the utility of advanced structural analysis methods in assessing the low-cycle fatigue lives of these anisotropic components. The turbine blade airfoil of the high-pressure stage of the SSME fuel turbopump was analyzed because it has a history of rapid crack initiation.

  8. Minnesota State Trails - Cartographic Version

    Data.gov (United States)

    Minnesota Department of Natural Resources — State trails maintained by Minnesota DNR Division of Parks and Trails, with geometry modified to support cartographic rendering and labeling. These trails have...

  9. A Trail of Roses

    DEFF Research Database (Denmark)

    Ørum, Tania

    2015-01-01

    a trail of roses through Danish 1960s art. The trail leads from Nielsen’s reading of Stein’s rose to the Danish composer Henning Christiansen, who put the sentence to music in his orchestral work A Rose for Miss Stein (1965). The chain of roses was continued by the painter and performance artist...

  10. Intermetallic blades for fabric cutting. CRADA final report

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-08-01

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

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

    Science.gov (United States)

    Ulker, Fatma Demet; Nitzsche, Fred

    2012-04-01

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

  12. The influence of trailed vorticity on flutter speed estimations

    DEFF Research Database (Denmark)

    Pirrung, Georg; Aagaard Madsen, Helge; Kim, Taeseong

    2014-01-01

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM...... influence of the near wake model on the aeroelastic stability of the blades of the NREL 5 MW turbine in overspeed conditions is investigated in the second part of the paper. The analysis is based on a runaway case in which the turbine is free to speed up without generator torque and vibrations start...... building up at a critical rotor speed. Blades with modified torsional and flapwise stiffness are also investigated. A flutter analysis is often part of the stability investigations for new blades but is normally carried out with engineering models that do not include the influence of unsteady trailed...

  13. DRBE comet trails

    Energy Technology Data Exchange (ETDEWEB)

    Arendt, Richard G., E-mail: Richard.G.Arendt@nasa.gov [CREST/UMBC, Code 665, NASA/GSFC, Greenbelt, MD 20771 (United States)

    2014-12-01

    Re-examination of the Cosmic Background Explorer Diffuse Infrared Background Experiment (DIRBE) data reveals the thermal emission of several comet dust trails. The dust trails of 1P/Halley, 169P/NEAT, and 3200 Phaethon have not been previously reported. The known trails of 2P/Encke and 73P/Schwassmann–Wachmann 3 are also seen. The dust trails have 12 and 25 μm surface brightnesses of <0.1 and <0.15 MJy sr{sup −1}, respectively, which is <1% of the zodiacal light intensity. The trails are very difficult to see in any single daily image of the sky, but are evident as rapidly moving linear features in movies of the DIRBE data. Some trails are clearest when crossing through the orbital plane of the parent comet, but others are best seen at high ecliptic latitudes as the Earth passes over or under the dust trail. All these comets have known associations with meteor showers. This re-examination also reveals 1 additional comet and 13 additional asteroids that had not previously been recognized in the DIRBE data.

  14. DIRBE Comet Trails

    CERN Document Server

    Arendt, Richard G

    2014-01-01

    Re-examination of the COBE DIRBE data reveals the thermal emission of several comet dust trails. The dust trails of 1P/Halley, 169P/NEAT, and 3200 Phaethon have not been previously reported. The known trails of 2P/Encke, and 73P/Schwassmann-Wachmann 3 are also seen. The dust trails have 12 and 25 micron surface brightnesses of <0.1 and <0.15 MJy/sr, respectively, which is <1% of the zodiacal light intensity. The trails are very difficult to see in any single daily image of the sky, but are evident as rapidly moving linear features in movies of the DIRBE data. Some trails are clearest when crossing through the orbital plane of the parent comet, but others are best seen at high ecliptic latitudes as the Earth passes over or under the dust trail. All these comets have known associations with meteor showers. This re-examination also reveals one additional comet and 13 additional asteroids that had not previously been recognized in the DIRBE data.

  15. DIRBE Comet Trails

    Science.gov (United States)

    Arendt, Richard G.

    2014-12-01

    Re-examination of the Cosmic Background Explorer Diffuse Infrared Background Experiment (DIRBE) data reveals the thermal emission of several comet dust trails. The dust trails of 1P/Halley, 169P/NEAT, and 3200 Phaethon have not been previously reported. The known trails of 2P/Encke and 73P/Schwassmann-Wachmann 3 are also seen. The dust trails have 12 and 25 μm surface brightnesses of \\lt 0.1 and \\lt 0.15 MJy sr-1, respectively, which is \\lt 1% of the zodiacal light intensity. The trails are very difficult to see in any single daily image of the sky, but are evident as rapidly moving linear features in movies of the DIRBE data. Some trails are clearest when crossing through the orbital plane of the parent comet, but others are best seen at high ecliptic latitudes as the Earth passes over or under the dust trail. All these comets have known associations with meteor showers. This re-examination also reveals 1 additional comet and 13 additional asteroids that had not previously been recognized in the DIRBE data.

  16. Ultrasonic evaluation of the effects of compressive residual stresses on aircraft engine turbine blades subjected to high cycle fatigue

    Science.gov (United States)

    Bray, Don E.; Suh, Ui; Hough, C. L. ``Mickey''

    2002-05-01

    Experiments conducted on titanium (Ti-64) turbine blades with the LCR ultrasonic wave at 20 MHz showed significant differences in untreated blades and blades treated to increase the subsurface compressive residual stress. Group 1 showed significant differences in the treated and untreated areas, the top and bottom of the blades, high cycle fatigue and cracked and uncracked conditions. Group 2 blades showed significant difference between untreated and treated travel-times at probes located at the blade leading edge.

  17. Ultrasonic evaluation of the effects of compressive residual stresses on aircraft engine turbine blades subjected to high cycle fatigue

    International Nuclear Information System (INIS)

    Experiments conducted on titanium (Ti-64) turbine blades with the LCR ultrasonic wave at 20 MHz showed significant differences in untreated blades and blades treated to increase the subsurface compressive residual stress. Group 1 showed significant differences in the treated and untreated areas, the top and bottom of the blades, high cycle fatigue and cracked and uncracked conditions. Group 2 blades showed significant difference between untreated and treated travel-times at probes located at the blade leading edge

  18. 大型风电叶片后缘最大弦长区域稳定性研究%BUCKLING STABILITY RESEARCH ON THE MAXIMUM CHORD REGION OF WIND TURBINE BLADE TRAILING EDGE

    Institute of Scientific and Technical Information of China (English)

    苏成功; 李成良; 鲁晓锋

    2015-01-01

    复合材料风电叶片最大弦长区域后缘通常为板壳结构,在风载作用下发生较大变形,是叶片较频繁出现损坏的区域.采用有限元的特征值屈曲分析方法,分析了蒙皮设计、加筋和安装第三个腹板这几种不同的结构设计形式对屈曲因子及叶片重量(成本)的影响.比较了不同设计下叶片重量与屈曲因子之间的关系,从而找到稳定性最好且成本最优的设计方案.研究结果表明,叶片要达到相同的屈曲因子时,安装第三个腹板是叶片增重最小、成本最优的设计方案.

  19. The influence of trailed vorticity on flutter speed estimations

    International Nuclear Information System (INIS)

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM) theory, which is coupled with Beddoes' near wake model for trailed vorticity. The first part of this work outlines the implementation in HAWC2, with a focus on the interaction of the induction from the blade based near wake model with the induction from the polar grid based BEM model in HAWC2. The influence of the near wake model on the aeroelastic stability of the blades of the NREL 5 MW turbine in overspeed conditions is investigated in the second part of the paper. The analysis is based on a runaway case in which the turbine is free to speed up without generator torque and vibrations start building up at a critical rotor speed. Blades with modified torsional and flapwise stiffness are also investigated. A flutter analysis is often part of the stability investigations for new blades but is normally carried out with engineering models that do not include the influence of unsteady trailed vorticity. Including this influence results in a slightly increased safety margin against classical flutter in all simulated cases

  20. Computational method for the design of wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-15

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

  1. TourismTrails_GMNFTRAILS

    Data.gov (United States)

    Vermont Center for Geographic Information — GMNFTRAILS contains minor Forest Service roads and all trails within the proclamation boundary of the Green Mountain National Forest and many of the public roads...

  2. Continental Divide Trail

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This shapefile was created to show the proximity of the Continental Divide to the Continental Divide National Scenic Trail in New Mexico. This work was done as part...

  3. Minnesota Water Trails

    Data.gov (United States)

    Minnesota Department of Natural Resources — This shapefile describes water trails in the State of Minnesota as designated through legislation and recognized by the Department of Natural Resources. The...

  4. State Park Trails

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data set is a collection of ArcView shapefiles (by park) of trails within statutory boundaries of individual MN State Parks, State Recreation Areas and State...

  5. 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.

  6. Ice-impact analysis of blades

    Science.gov (United States)

    Chamis, C. C.; Murthy, P. L. N.; Singhal, S. N.; Reddy, E. S.

    1994-01-01

    A computational capability is described for evaluating the ice-impact on engine blades made from composites. The ice block is modeled as an equivalent spherical object and has the velocity opposite to that of the aircraft with direction parallel to the engine axis. A finer finite element mesh is used for a portion of the blade near the impact region compared to the course mesh for the rest of the blade. The effects of ice size and velocity on the average leading edge strain are evaluated for a simulated unswept composite propfan blade. Parametric studies are performed to assess the blade structural responses due to the ice-impact at various locations along the span. It is found that: (1) for a given engine speed, a critical ice speed exists that corresponds to the maximum strain; and (2) the tip bending type frequencies increase after impact while the torsion frequencies decrease.

  7. 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 ...

  8. Flow separation on wind turbines blades

    Science.gov (United States)

    Corten, G. P.

    2001-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  11. Micromachined cutting blade formed from {211}-oriented silicon

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, James G.; Sniegowski, Jeffry J.; Montague, Stephen

    2003-09-09

    A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

  12. Micromachined cutting blade formed from {211}-oriented silicon

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, James G. (Albuquerque, NM); Fleming, legal representative, Carol (Burbank, CA); Sniegowski, Jeffry J. (Tijeras, NM); Montague, Stephen (Albuquerque, NM)

    2011-08-09

    A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

  13. Study of Wear of Pitched Blade Impellers

    Directory of Open Access Journals (Sweden)

    I. Fořt

    2000-01-01

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

  14. Neural control of helicopter blade-vortex interaction noise

    Science.gov (United States)

    Glaessel, Holger; Kloeppel, Valentin; Rudolph, Stephan

    2001-06-01

    Significant reduction of helicopter blade-vortex interaction (BVI) noise is currently one of the most advanced research topics in the helicopter industry. This is due to the complex flow, the close aerodynamic and structural coupling, and the interaction of the blades with the trailing edge vortices. Analytical and numerical modeling techniques are therefore currently still far from a sufficient degree of accuracy to obtain satisfactory results using classical model based control concepts. Neural networks with a proven potential to learn nonlinear relationships implicitly encoded in a training data set are therefore an appropriate and complementary technique for the alternative design of a nonlinear controller for BVI noise reduction. For nonlinear and adaptive control different neural control strategies have been proposed. Two possible approaches, a direct and an indirect neural controller are described. In indirect neural control, the plant has to be identified first by training a network with measured data. The plant network is then used to train the controller network. On the other hand the direct control approach does not rely on an explicit plant model, instead a specific training algorithm (like reinforcement learning) uses the information gathered from interactions with the environment. In the investigation of the BVI noise phenomena, helicopter developers have undertaken substantial efforts in full scale flight tests and wind tunnel experiments. Data obtained in these experiments have been adequately preprocessed using wavelet analysis and filtering techniques and are then used in the design of a neural controller. Neural open-loop control and neural closed-loop control concepts for the BVI noise reduction problem are conceived, simulated and compared against each other in this work in the above mentioned framework.

  15. 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)

  16. 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.

  17. 9th TRAIL Congress 2006, TRAIL in MOTION

    OpenAIRE

    TRAIL RESEARCH SCHOOL

    2006-01-01

    TRAIL is a Research School on Transport, Infrastructure and Logistics. TRAIL trains Ph.D. candidates and performs scientific and applied scientific research in the fields of mobility, transport, logistics, traffic, infrastructure and transport systems. TRAIL is a collaborative initiative of five Dutch universities, and is accredited as research school since 1997

  18. Optimization of Wind Turbine Airfoils/Blades and Wind Farm Layouts

    Science.gov (United States)

    Chen, Xiaomin

    Shape optimization is widely used in the design of wind turbine blades. In this dissertation, a numerical optimization method called Genetic Algorithm (GA) is applied to address the shape optimization of wind turbine airfoils and blades. In recent years, the airfoil sections with blunt trailing edge (called flatback airfoils) have been proposed for the inboard regions of large wind-turbine blades because they provide several structural and aerodynamic performance advantages. The FX, DU and NACA 64 series airfoils are thick airfoils widely used for wind turbine blade application. They have several advantages in meeting the intrinsic requirements for wind turbines in terms of design point, off-design capabilities and structural properties. This research employ both single- and multi-objective genetic algorithms (SOGA and MOGA) for shape optimization of Flatback, FX, DU and NACA 64 series airfoils to achieve maximum lift and/or maximum lift to drag ratio. The commercially available software FLUENT is employed for calculation of the flow field using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a two-equation Shear Stress Transport (SST) turbulence model and a three equation k-kl-o turbulence model. The optimization methodology is validated by an optimization study of subsonic and transonic airfoils (NACA0012 and RAE 2822 airfoils). In this dissertation, we employ DU 91-W2-250, FX 66-S196-V1, NACA 64421, and Flat-back series of airfoils (FB-3500-0050, FB-3500-0875, and FB-3500-1750) and compare their performance with S809 airfoil used in NREL Phase II and III wind turbines; the lift and drag coefficient data for these airfoils sections are available. The output power of the turbine is calculated using these airfoil section blades for a given B and lambda and is compared with the original NREL Phase II and Phase III turbines using S809 airfoil section. It is shown that by a suitable choice of airfoil section of HAWT blade, the power generated

  19. In-phase thermal-mechanical fatigue investigation on hollow single crystal turbine blades

    Institute of Scientific and Technical Information of China (English)

    Wang Rongqiao; Jing Fulei; Hu Dianyin

    2013-01-01

    Thermal-mechanical fatigue (TMF) is the primary cause of failure of nickel-based single crystal turbine blades. TMF experiments have been performed on the critical section which is sub-jected to the most serious damage and determined by numerical calculation combined with service failure experience. An experimental system including the loading, heating, air cooling, water cool-ing, and control subsystems, is constructed to satisfy the TMF experimental requirements. This experimental system can simulate the stress field, temperature field, air cooling process, and TMF spectrum on the critical section under service conditions in a laboratory environment. A metal loading device and a new induction coil are developed to achieve the required stress and tempera-ture distributions on the critical section, respectively. TMF experimental results have indicated that cracks initiated at the trailing edge of the suction surface on the critical section. Based on these experiments, life prediction and failure analysis of hollow single crystal turbine blades can be inves-tigated.

  20. The dynamics of foraging trails in the tropical arboreal ant Cephalotes goniodontus.

    Science.gov (United States)

    Gordon, Deborah M

    2012-01-01

    The foraging behavior of the arboreal turtle ant, Cephalotes goniodontus, was studied in the tropical dry forest of western Mexico. The ants collected mostly plant-derived food, including nectar and fluids collected from the edges of wounds on leaves, as well as caterpillar frass and lichen. Foraging trails are on small pieces of ephemeral vegetation, and persist in exactly the same place for 4-8 days, indicating that food sources may be used until they are depleted. The species is polydomous, occupying many nests which are abandoned cavities or ends of broken branches in dead wood. Foraging trails extend from trees with nests to trees with food sources. Observations of marked individuals show that each trail is travelled by a distinct group of foragers. This makes the entire foraging circuit more resilient if a path becomes impassable, since foraging in one trail can continue while a different group of ants forms a new trail. The colony's trails move around the forest from month to month; from one year to the next, only one colony out of five was found in the same location. There is continual searching in the vicinity of trails: ants recruited to bait within 3 bifurcations of a main foraging trail within 4 hours. When bait was offered on one trail, to which ants recruited, foraging activity increased on a different trail, with no bait, connected to the same nest. This suggests that the allocation of foragers to different trails is regulated by interactions at the nest. PMID:23209749

  1. Measurement of Trailing Vortices around a Hydrofoil Impeller with PIV and Large Eddy Simulation%翼型桨叶片尾涡结构的PIV实测与LES模拟研究

    Institute of Scientific and Technical Information of China (English)

    蔡清白; 戴干策

    2011-01-01

    The trailing vortices around a hydrofoil impeller were investigated in a 0.383 m I.d. Stirred tank with a 0.188 m I.d. Hydrofoil impeller using PIV and LES. The comparison between angle-averaged axial velocities by LES and PIV data was in very good agreement, verifying the validity and effectiveness of LES simulation. The presence of trailing vortices formed around the hydrofoil impeller blades were indicated by the mean velocity vectors near the edge of blades, the contours of turbulence levels and kinetic energy of turbulence. It was found that single trailing vortex formed around each blade. The vortex axis was identified to fall on the cylinder swept by the blade tip. The effect of trailing vortices on the turbulence structure was also discussed. The maximum normalized kinetic turbulence energy k/Vtip2 was about 0.04-0.06, which was located at 0.5

  2. Wake evolution and trailing vortex instabilities

    Science.gov (United States)

    Odemark, Ylva; Fransson, Jens H. M.

    2011-11-01

    The production losses and inhomogeneous loads of wind power turbines placed in the wake of another turbine is a well-known problem when building new wind power farms, and a subject of intensive research. The present work aims at developing an increased understanding of the behaviour of turbine wakes, with special regard to wake evolution and the stability of the trailing vortices. Single point velocity measurements with hot-wire anemometry were performed in the wake of a small-scale model turbine. The model was placed in the middle of the wind tunnel test section, outside the boundary layers from the wind tunnel walls. In order to study the stability of the wake and the trailing vortices, a disturbance was introduced at the end of the nacelle. This was accomplished through two orifices perpendicular to the main flow, which were connected to a high-pressure tank and two fast-switching valves. Both varicose and sinusoidal modes of different frequencies could be triggered. By also triggering the measurements on the blade passage, the meandering of the wake and the disturbance frequency, phase averaged results could be computed. The results for different frequencies as well as studies of wake evolution will be presented.

  3. An experimental study of static and oscillating rotor blade sections in reverse flow

    Science.gov (United States)

    Lind, Andrew Hume

    The rotorcraft community has a growing interest in the development of high-speed helicopters to replace outdated fleets. One barrier to the design of such helicopters is the lack of understanding of the aerodynamic behavior of retreating rotor blades in the reverse flow region. This work considers two fundamental models of this complex unsteady flow regime: static and oscillating (i.e., pitching) airfoils in reverse flow. Wind tunnel tests have been performed at the University of Maryland (UMD) and the United States Naval Academy (USNA). Four rotor blade sections are considered: two featuring a sharp geometric trailing edge (NACA 0012 and NACA 0024) and two featuring a blunt geometric trailing edge (ellipse and cambered ellipse). Static airfoil experiments were performed at angles of attack through 180 deg and Reynolds numbers up to one million, representative of the conditions found in the reverse flow region of a full-scale high-speed helicopter. Time-resolved velocity field measurements were used to identify three unsteady flow regimes: slender body vortex shedding, turbulent wake, and deep stall vortex shedding. Unsteady airloads were measured in these three regimes using unsteady pressure transducers. The magnitude of the unsteady airloads is high in the turbulent wake regime when the separated shear layer is close to the airfoil surface and in deep stall due to periodic vortex-induced flow. Oscillating airfoil experiments were performed on a NACA 0012 and cambered ellipse to investigate reverse flow dynamic stall characteristics by modeling cyclic pitching kinematics. The parameter space spanned three Reynolds numbers (165,000; 330,000; and 500,000), five reduced frequencies between 0.100 and 0.511, three mean pitch angles (5,10, and 15 deg), and two pitch amplitudes (5 deg and 10 deg). The sharp aerodynamic leading edge of the NACA 0012 airfoil forces flow separation resulting in deep dynamic stall. The number of associated vortex structures depends strongly

  4. 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.

  5. 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.

  6. Wind Turbine Blade

    DEFF Research Database (Denmark)

    2010-01-01

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

  7. Turbine blade and non-integral platform with pin attachment

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Christian Xavier; Eng, Darryl; Marra, John J.

    2016-08-02

    Platforms (36, 38) span between turbine blades (23, 24, 25) on a disk (32). Each platform may be individually mounted to the disk by a pin attachment (42). Each platform (36) may have a rotationally rearward edge portion (50) that underlies a forward portion (45) of the adjacent platform (38). This limits centrifugal bending of the rearward portion of the platform, and provides coolant sealing. The rotationally forward edge (44A, 44B) of the platform overlies a seal element (51) on the pressure side (28) of the forwardly adjacent blade, and does not underlie a shelf on that blade. The pin attachment allows radial mounting of each platform onto the disk via tilting (60) of the platform during mounting to provide mounting clearance for the rotationally rearward edge portion (50). This facilitates quick platform replacement without blade removal.

  8. Differences in the impacts of formal and informal recreational trails on urban forest loss and tree structure.

    Science.gov (United States)

    Ballantyne, Mark; Pickering, Catherine Marina

    2015-08-15

    Recreational trails are one of the most common types of infrastructure used for nature-based activities such as hiking and mountain biking worldwide. Depending on their design, location, construction, maintenance and use, these trails differ in their environmental impacts. There are few studies, however, comparing the impacts of different trail types including between formal management-created trails and informal visitor-created trails. Although both types of trails can be found in remote natural areas, dense networks of them often occur in forests close to cities where they experience intense visitor use. To assess the relative impacts of different recreational trails in urban forests, we compared the condition of the trail surface, loss of forest strata and changes in tree structure caused by seven types of trails (total network 46.1 km) traversing 17 remnants of an endangered urban forest in Australia. After mapping and classifying all trails, we assessed their impact on the forest condition at 125 sites (15 sites per trail type, plus 15 control sites within undisturbed forest). On the trail sites, the condition of the trail surface, distance from the trail edge to four forest strata (litter, understory, midstorey and tree cover) and structure of the tree-line were assessed. Informal trails generally had poorer surface conditions and were poorly-designed and located. Per site, formal and informal trails resulted in similar loss of forest strata, with wider trails resulting in greater loss of forest. Because there were more informal trails, however, they accounted for the greatest cumulative forest loss. Structural impacts varied, with the widest informal trails and all formal hardened trails resulting in similar reductions in canopy cover and tree density but an increase in saplings. These structural impacts are likely a function of the unregulated and intense use of large informal trails, and disturbance from the construction and maintenance of formal trails

  9. BCDC Bay Trail Alignment 2009

    Data.gov (United States)

    California Department of Resources — The Bay Trail provides easily accessible recreational opportunities for outdoor enthusiasts, including hikers, joggers, bicyclists and skaters. It also offers a...

  10. Eddy current inspection of stationary blade rings

    International Nuclear Information System (INIS)

    Stationary turbine blade rings in a US power plant have experienced chloride-induced cracking. Failure analysis determined two types of cracking mechanisms: corrosion fatigue cracking confined to the leading edge of the outer shroud; and stress corrosion cracking present all over the blade surface. Fluorescent dye penetrant is typically used to detect and size cracks. However, it requires cleaning the blade rings by sandblasting to obtain reliable inspection results. Sand blasting in turn requires sealing the lower half of the turbine housing to prevent sand from contaminating the rest of the power plant components. Furthermore, both the penetrant examination and the removal of the sand are time consuming and costly. An alternative NDE technique is desirable which requires no pre-cleaning of the blade and a quick go/no-go inspection with the capability of estimating the crack length. This paper presents an innovative eddy current technique which meets the desired objectives by incorporating the use of specially designed contoured scanners equipped with an array of pancake coils. A set of eddy current pancake coils housed in three different scanners is used to manually scan and inspect the convex side of the stationary blade rings. The pancake coils are operated in a transmit/receive mode using two separate eddy current instruments. This paper presents the inspection concept, including scanner and probe designs, and test results from the various stages of multiple blade rings

  11. 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

  12. The statistics of collapsing square lattice trails with a fixed number of vertices of degree 4

    International Nuclear Information System (INIS)

    A trail on the square lattice with a fixed number, k, of vertices of degree 4 is called a k-trail. We model polymer collapse using k-trails by incorporating an interaction energy which is proportional to the number of nearest-neighbour contact edges of the trail. It is known that the number of square lattice n-edge closed (open) k-trails can be bounded above and below (to O(nk)) by the number of n-step self-avoiding circuits (walks). This along with pattern theorems for self-interacting self-avoiding circuits and walks are used herein to establish upper and lower bounds (to O(nk)) for the collapsing free energy of k-trails in terms of self-avoiding circuits or walks, as appropriate. We also use pattern theorems to obtain bounds on the limiting nearest-neighbour contact density for collapsing k-trails. Finally, we investigate k-trails with a fixed density of nearest-neighbour contacts and show that their limiting entropy per monomer is independent of k

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-03-01

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

  14. 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...

  15. The influence of trailed vorticity on flutter speed estimations

    OpenAIRE

    Pirrung, Georg; Aagaard Madsen , Helge; Kim, Taeseong

    2014-01-01

    This paper briefly describes the implementation of a coupled near and far wake model for wind turbine rotor induction in the aeroelastic code HAWC2 and its application for flutter analysis of the NREL 5 MW wind turbine. The model consists of a far wake part based on Blade Element Momentum (BEM) theory, which is coupled with Beddoes' near wake model for trailed vorticity. The first part of this work outlines the implementation in HAWC2, with a focus on the interaction of the induction from the...

  16. Thermal-barrier-coated turbine blade study

    Science.gov (United States)

    Siemers, P. A.; Hillig, W. B.

    1981-01-01

    The effects of coating TBC on a CF6-50 stage 2 high-pressure turbine blade were analyzed with respect to changes in the mean bulk temperature, cooling air requirements, and high-cycle fatigue. Localized spallation was found to have a possible deleterious effect on low-cycle fatigue life. New blade design concepts were developed to take optimum advantage of TBCs. Process and material development work and rig evaluations were undertaken which identified the most promising combination as ZrO2 containing 8 w/o Y2O3 applied by air plasma spray onto a Ni22Cr-10Al-1Y bond layer. The bond layer was applied by a low-pressure, high-velocity plasma spray process onto the base alloy. During the initial startup cycles the blades experienced localized leading edge spallation caused by foreign objects.

  17. 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.

  18. Heat Transfer on a Film-Cooled Rotating Blade

    Science.gov (United States)

    Garg, Vijay K.

    1999-01-01

    A multi-block, three-dimensional Navier-Stokes code has been used to compute heat transfer coefficient on the blade, hub and shroud for a rotating high-pressure turbine blade with 172 film-cooling holes in eight rows. Film cooling effectiveness is also computed on the adiabatic blade. Wilcox's k-omega model is used for modeling the turbulence. Of the eight rows of holes, three are staggered on the shower-head with compound-angled holes. With so many holes on the blade it was somewhat of a challenge to get a good quality grid on and around the blade and in the tip clearance region. The final multi-block grid consists of 4784 elementary blocks which were merged into 276 super blocks. The viscous grid has over 2.2 million cells. Each hole exit, in its true oval shape, has 80 cells within it so that coolant velocity, temperature, k and omega distributions can be specified at these hole exits. It is found that for the given parameters, heat transfer coefficient on the cooled, isothermal blade is highest in the leading edge region and in the tip region. Also, the effectiveness over the cooled, adiabatic blade is the lowest in these regions. Results for an uncooled blade are also shown, providing a direct comparison with those for the cooled blade. Also, the heat transfer coefficient is much higher on the shroud as compared to that on the hub for both the cooled and the uncooled cases.

  19. 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.

  20. Turbine Airfoil With CMC Leading-Edge Concept Tested Under Simulated Gas Turbine Conditions

    Science.gov (United States)

    Robinson, R. Craig; Hatton, Kenneth S.

    2000-01-01

    metal vane was tested for a total of 150 cycles. Both the leading edge and trailing edge of the blade exhibited fatigue cracking and burn-through similar to the failures experienced in service by the F402 engine. Next, an airfoil, fitted with the ceramic leading edge insert, was exposed for 200 cycles. The temperature response of those HPBR cycles indicated a reduced internal metal temperature, by as much as 600 F at the midspan location for the same surface temperature (2100 F). After testing, the composite insert appeared intact, with no signs of failure on either the vane s leading or trailing edge. Only a slight oxide scale, as would be expected, was noted on the insert. Overall, the CMC insert performed similarly to a thick thermal barrier coating. With a small air gap between the metal and the SiC/SiC leading edge, heat transfer from the CMC to the metal alloy was low, effectively lowering the temperatures. The insert's performance has proven that an uncooled CMC can be engineered and designed to withstand the thermal up-shock experienced during the severe lift conditions in the Pegasus engine. The design of the leading-edge insert, which minimized thermal stresses in the SiC/SiC CMC, showed that the CMC/metal assembly can be engineered to be a functioning component.

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

    Science.gov (United States)

    Lark, R. F.

    1983-01-01

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

  2. Unsteady flow over disc turbine blades

    Science.gov (United States)

    Popiolek, Z.; Whitelaw, J. H.; Yianneskis, M.

    Measurements are presented of the mean and turbulence structure of the trailing vortices produced over disc turbine blades in stirred vessels. The results were obtained by ensemble-averaging the velocities measured by laser-Doppler anemometry over intervals of one degree of revolution and are compared with results obtained by ensemble-averaging over the whole 360 deg cycle. A vortical pattern was permanently present up to 20 degrees behind each blade, and was subjected to an erratic motion due to the formation of a whirlpool type of vortex in the free surface of the water. The velocities in the vortices were of the order of 0.25 of the blade tip velocity, V(tip). The measured kinetic energy of turbulence reached maxima of 0.19 V(tip)squared and the fluctuating quantities measured indicated that strong anisotropy prevails in the impeller stream. Comparison of turbulence results with those obtained by sampling over the whole 360 degrees of revolution shows that the former can be overestimated by as much as four times.

  3. How kelp produce blade shapes suited to different flow regimes: A new wrinkle.

    Science.gov (United States)

    Koehl, M A R; Silk, W K; Liang, H; Mahadevan, L

    2008-12-01

    Many species of macroalgae have flat, strap-like blades in habitats exposed to rapidly flowing water, but have wide, ruffled "undulate" blades at protected sites. We used the giant bull kelp, Nereocystis luetkeana, to investigate how these ecomorphological differences are produced. The undulate blades of N. luetkeana from sites with low flow remain spread out and flutter erratically in moving water, thereby not only enhancing interception of light, but also increasing drag. In contrast, strap-like blades of kelp from habitats with rapid flow collapse into streamlined bundles and flutter at low amplitude in flowing water, thus reducing both drag and interception of light. Transplant experiments in the field revealed that shape of the blade in N. luetkeana is a plastic trait. Laboratory experiments in which growing blades from different sites were subjected to tensile forces that mimicked the hydrodynamic drag experienced by blades in different flow regimes showed that change in shape is induced by mechanical stress. During growth experiments in the field and laboratory, we mapped the spatial distribution of growth in both undulate and strap-like blades to determine how these different morphologies were produced. The highest growth rates occur near the proximal ends of N. luetkeana blades of both morphologies, but the rates of transverse growth of narrow, strap-like blades are lower than those of wide, undulate blades. If rates of longitudinal growth at the edges of a blade exceed the rate of longitudinal growth along the midline of the blade, ruffles along the edges of the blade are produced by elastic buckling. In contrast, flat blades are produced when rates of longitudinal growth are similar across the width of a blade. Because ruffles are the result of elastic buckling, a compliant undulate N. luetkeana blade can easily be pushed into different configurations (e.g., the wavelengths of the ruffles along the edges of the blade can change, and the whole blade can

  4. Modal Analysis for Crack Detection in Small Wind Turbine Blades

    DEFF Research Database (Denmark)

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

    2013-01-01

    The aim of the present paper is to evaluate structural health monitoring (SHM) techniques based on modal analysis for crack detection in small wind turbine blades. A finite element (FE) model calibrated to measured modal parameters will be introduced to cracks with different sizes along one edge of...... the blade. Changes in modal parameters from the FE model are compared with data obtained from experimental tests. These comparisons will be used to validate the FE model and subsequently discuss the usability of SHM techniques based on modal parameters for condition monitoring of wind turbine blades....

  5. Vibrational analyses of cracked pre-twisted blades

    Science.gov (United States)

    Chen, L. W.; Jeng, C. H.

    1993-01-01

    A finite element model is utilized to analyze the vibrational behavior of a pre-twisted rotating blade with a single edge crack. This model can satisfy both geometric boundary conditions and natural boundary conditions of the blade. The effects of the transverse shear deformation, rotary inertia and the pre-twisted angle are taken into account. The influences of the crack location and the crack size on natural frequencies, buckling loads and dynamic instability regions are studied. It is found that a crack has great influences on these dynamic characteristics of the rotating blade.

  6. Analyzing Trails in Complex Networks

    CERN Document Server

    Costa, L F

    2006-01-01

    Even more interesting than the intricate organization of complex networks are the dynamics of systems underlined by such structures. Among the many types of dynamics, one particularly interesting category involves the evolution of trails left by random walks and dilating processes as moving agents progress through a complex network. Once such a trail occurs, important implied problem includes the reconstruction of the trail and the identification of its source. The present work addresses these issues while taking into account permanent and transient self-avoiding trails, the latter being further subdivided into Poissonian and evanescent types. Erd\\H{o}s-R\\'enyi and Barab\\'asi-Albert models are considered. Several interesting results are obtained.

  7. TRAIL - a tokamak rail gun limiter

    International Nuclear Information System (INIS)

    An attractive new limiter concept is investigated. The TRAIL (Tokamak Rail Gun Limiter) system impacts a stream of moderate velocity pellets (100 to 200 m/sec) through the plasma edge region to absorb energy and define the plasma boundary. The pellets are recycled after cooling, to the injector of an E-M mass accelerator. Heat fluxes of approx. 30,000 W/cm2 can be readily accommodated by the pellets, with very low recirculating power requirements (approx. 0.1%) for the accelerator. The mass accelerator velocity requirements are well within the present state of the art (several Km/sec). Accelerators injecting pellets at approx. 1 Km/sec can be used to control local plasma temperature and current profiles and to act as energy absorbers to shut down the plasma without damage to the first wall if a plasma disruption occurs. (author)

  8. Trail-A Tokamak RAIL Gun Limiter

    International Nuclear Information System (INIS)

    An attractive new limiter concept is investigated. The Tokamak RAIl Gun Limiter (TRAIL) system directs a stream of moderate velocity pellets (100 to 200 m/s) through the plasma edge region to absorb energy and define the plasma boundary. The pellets are recycled, after cooling, to the injector in an electromagnetic mass accelerator. Heat fluxes of about30000 W/cm2 can be readily accommodated by the pellets, with very low recirculating power requirements ( about0.1%) for the accelerator. The mass accelerator velocity requirements are well within the present state of the art (several kilometres per second). Accelerators injecting pellets at about1 km/s can be used to control local plasma temperature and current profiles and to act as energy absorbers to shut down the plasma without damage to the first wall if a plasma disruption occurs

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

    DEFF Research Database (Denmark)

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

    Blade Root flap and Edge moments are measured on the blades of a 3.6MW offshore wind turbine in normal operation. Ten minute maxima of the measurements are sampled to determine the extreme blade root flap moment, edge moment and resultant moment over six month duration. A random subset of the...... measurements over a week is taken as input to stochastic load extrapolation whereby the one year extrapolated design extreme is obtained, which are then compared with the maximum extremes obtained from direct measurements over a six month period to validate the magnification in the load levels for the blade...... root flap moment, edge moment obtained by extrapolation. The validation yields valuable information on prescribing the slope of the local extrapolation curve at each mean wind speed. As an alternative to determining the contemporaneous loads for each primary extrapolated load, the blade root resultant...

  10. Trail pheromone disruption of Argentine ant trail formation and foraging.

    Science.gov (United States)

    Suckling, David Maxwell; Peck, Robert W; Stringer, Lloyd D; Snook, Kirsten; Banko, Paul C

    2010-01-01

    Trail pheromone disruption of invasive ants is a novel tactic that builds on the development of pheromone-based pest management in other insects. Argentine ant trail pheromone, (Z)-9-hexadecenal, was formulated as a micro-encapsulated sprayable particle and applied against Argentine ant populations in 400 m2 field plots in Hawai'i Volcanoes National Park. A widely dispersed point source strategy for trail pheromone disruption was used. Traffic rates of ants in bioassays of treated filter paper, protected from rainfall and sunlight, indicated the presence of behaviorally significant quantities of pheromone being released from the formulation for up to 59 days. The proportion of plots, under trade wind conditions (2–3 m s−1), with visible trails was reduced for up to 14 days following treatment, and the number of foraging ants at randomly placed tuna-bait cards was similarly reduced. The success of these trail pheromone disruption trials in a natural ecosystem highlights the potential of this method for control of invasive ant species in this and other environments. PMID:20077128

  11. Improved technique for computing vibrations of turbomachine blading

    International Nuclear Information System (INIS)

    Turbomachine blading vibration is one of the most important problems of modern industry since they result in endurance decrease. That is why, nowadays, developing vibration analysis techniques is the key point of turbooutfis designing. There are a lot of blading vibration methods that take into account various features of the concrete system. Methods developed for systems with revolving symmetry effectively use the fact that the natural vibration of such systems consists of several related modes groups. Recently, the method of modal models is getting more and more popular. Blades shape is rather complicated are integrated into systems such as packets, bladings, rotor wheels, etc. Accordingly, it is convenient to use the hierarchical mathematical models. 3D model fulfilled using FEM is very popular modeling technique as well. Usually, blade shape can be easily described using 20-modes isoparametric curvilinear finite elements with increased degree of approximation polynomials. Multivariate numerical analyses of vibration requires system dimension reduce. All elements in such systems are similar. The reduction can be performed using this feature. This allows one to operate with block matrixes of both the whole system and single blade. Usually, the dimension of the first block is approximately 10 times as big as the dimension of the rest. To obtain the matrix of the next blade it is necessary to modify the block corresponding to one of the edges and add the block corresponding to the other edge. This process should be continued recursively until all the blades are included into the matrix. This technique, on the contrary to superelement and condensation methods, corresponds to the complete finite element formulation of the problem. Computations for real systems are carried out using the technique described. The results are represented visually as stress and displacement fields. The peculiarities of packets and bladings vibrations are detected. Refs. 3 (author)

  12. Design, development, and hover testing of a helicopter rotor blade chord extension morphing system

    Science.gov (United States)

    Gandhi, Farhan; Hayden, Eric

    2015-03-01

    A rotor blade chord extension system was designed, fabricated and hover tested, using electromechanical and pneumatic actuation. A 1.5 in actuator stroke output in the spanwise direction was converted into chordwise motion of a trailing-edge plate (TEP), via a rigid link. On the hover stand, with a 20 V dc input, the electromechanical actuator was shown to fully extend and retract the plate at rotational speeds up to 385 RPM (which put the system at a centrifugal loading of 209.5 g, or 47.2% of that on a Black Hawk helicopter at 73% span). The configuration was changed to reduce the actuator force requirement for the pneumatic actuator. The rotor test facility allowed a maximum of 105 psi pressure input through the rotary union (significantly lower than the rating of the actuator). At these moderate pressure inputs, full TEP deployment was observed at 315 RPM (140.2 g, or 31.6% of that on a Black Hawk helicopter at 73% span). The model prediction of TEP displacement versus pressure showed good correlation with test results.

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-15

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

  15. 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.

  16. Effect of blade tip configuration on tip clearance loss of a centrifugal impeller

    Science.gov (United States)

    Ishida, Masahiro; Ueki, Hironobu; Senoo, Yasutoshi

    1989-06-01

    The effect of blade tip configuration on the tip clearance loss was examined experimentally using an unshrouded centrifugal impeller with backward-leaning blades. Tips with rounded edges, sharp square edges, and edges with end plates were tested. The observed tip clearance effects could be theoretically predicted by assuming reasonable values of the contraction coefficent alpha = 0.91 for the round edge, 0.73 for the sharp square edge, and 0.53 for the end-plate edge. The impeller efficiency was improved by about 1.5 point by reducing the contraction coefficient from 0.91 to 0.53. The effect of contraction coefficient on impeller efficiency depends on the ratio of leakage loss to the tip clearance loss. Improved efficiency for impellers with highly loaded blades is expected from reducing the contraction coefficient.

  17. 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.

  18. Numerical Simulation and Shrinkage Defects Prediction of a Turbine Blade Investment Casting

    Institute of Scientific and Technical Information of China (English)

    Jing TIAN; Xiang XUE; Yuebing ZHANG; Yalong GAO; Luzhi LIU; Qin SUN; Shiyou YUAN

    2003-01-01

    By adopting the solid modeling software SoldEdge and the enmeshment software SRIFCast as the pre-processingplatform, a Ni based alloy turbine blade was three-dimensionally modeled and automatically enmeshed. A softwarecode for numerical simulation of flui

  19. Rotational effects on turbine blade cooling

    Energy Technology Data Exchange (ETDEWEB)

    Govatzidakis, G.J.; Guenette, G.R.; Kerrebrock, J.L. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1995-10-01

    An experimental investigation of the influence of rotation on the heat transfer in a smooth, rectangular passage rotating in the orthogonal mode is presented. The passage simulates one of the cooling channels found in gas turbine blades. A constant heat flux is imposed on the model with either inward or outward flow. The effects of rotation and buoyancy on the Nusselt number were quantified by systematically varying the Rotation number, Density Ratio, Reynolds number, and Buoyancy parameter. The experiment utilizes a high resolution infrared temperature measurement technique in order to measure the wall temperature distribution. The experimental results show that the rotational effects on the Nusselt number are significant and proper turbine blade design must take into account the effects of rotation, buoyancy, and flow direction. The behavior of the Nusselt number distribution depends strongly on the particular side, axial position, flow direction, and the specific range of the scaling parameters. The results show a strong coupling between buoyancy and Corollas effects throughout the passage. For outward flow, the trailing side Nusselt numbers increase with Rotation number relative to stationary values. On the leading side, the Nusselt numbers tended to decrease with rotation near the inlet and subsequently increased farther downstream in the passage. The Nusselt numbers on the side walls generally increased with rotation. For inward flow, the Nusselt numbers generally improved relative to stationary results, but increases in the Nusselt number were relatively smaller than in the case of outward flow. For outward and inward flows, increasing the density ratio generally tended to decrease Nusselt numbers on the leading and trailing sides, but the exact behavior and magnitude depended on the local axial position and specific range of Buoyancy parameters.

  20. Effect of blade shape on the performance of six-bladed disk turbine impellers

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, J.M.T.; Orvalho, S.C.P.; Rodrigues, A.M.A.F.; Alves, S.S.

    2000-01-01

    Different modifications of the Rushton turbine were studied in a dual-impeller agitated tank (T = 0.4 m), to find the effect of blade form on power draw, turbulent dispersion, gas handling capacity, mixing, gas holdup, and mass-transfer rate performance under turbulent agitation in an air-water system. Blade streamlining was found to lead to a lower ungassed power number, a higher gas flow number before flooding, and increased insensitivity of impeller power dissipation to the gassing rate. This is consistent with the formation of smaller trailing vortices and ventilated cavities behind the blade. At the same power input and superficial gas velocity, however, the different impellers provided the same mixing time t{sub 0.05}, gas holdup {epsilon}{sub G}, and specific mass-transfer coefficient K{sub L}{alpha}. Each of these variables correlates with the specific power input P{sub G}/V{sub L}, clearly suggesting that a better performance may be expected after retrofitting of Rushton turbines with streamlined impellers.

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

    Science.gov (United States)

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

    2013-01-01

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

  2. Interdependence of centrifugal compressor blade geometry and relative flow field

    Science.gov (United States)

    Krain, H.

    1985-03-01

    The influence of the impeller blade geometry on the calculated relative flow field has been studied by means of an impeller design program available at DFVLR (Krain, 1984). Several geometrical parameters were varied, however, the meridional channel geometry was always kept constant. By this approach the blade wrap angle has been found to react significantly on the relative flow which is illustrated by comparing two designs with different wrap angles. Primarily in the hub/leading edge area a better boundary layer flow connected with a reduction of blade loading was obtained by increasing the wrap angle. But also in the shroud/pressure side area the increased blade looping attributed to an additional flow stabilization.

  3. Alaska gold rush trails study: Preliminary draft

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Preliminary study draft, with maps, of seven gold rush trails in Alaska, to determine suitability for inclusion in the National Scenic Trails system and their...

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

    Science.gov (United States)

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

    2016-01-01

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

  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. Trail formation based on directed pheromone deposition

    OpenAIRE

    Boissard, Emmanuel; Degond, Pierre; Motsch, Sébastien

    2011-01-01

    We propose an Individual-Based Model of ant-trail formation. The ants are modeled as self-propelled particles which deposit directed pheromones and interact with them through alignment interaction. The directed pheromones intend to model pieces of trails, while the alignment interaction translates the tendency for an ant to follow a trail when it meets it. Thanks to adequate quantitative descriptors of the trail patterns, the existence of a phase transition as the ant-pheromone interaction fr...

  7. Recreational Demand for Equestrian Trail-Riding

    OpenAIRE

    Blackwell, Melanie; Pagoulatos, Angelos; Hu, Wuyang; Auchter, Katharine

    2009-01-01

    Using data collected from a combination of on-site and on-line surveys, this study examines recreational demand for equestrian trail-riding in Kentucky. A truncated, negative binomial regression is applied to analyze individuals’ visitation behavior consistent with a travel cost model. Results suggest that distance is the most significant determinant of average annual visits to a particular site. Various trail site characteristics, such as trail length, scenic overlooks, and trail markers, ...

  8. 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.

  9. Perceptual Geography through Urban Trails.

    Science.gov (United States)

    Dove, Jane

    1997-01-01

    Describes a project whereby geography students were charged with designing an urban trail (city walk with informational markers) that would accommodate specific groups. Chosen groups included people with physical disabilities, 10-year olds, and those interested in local street art. Discusses the cognitive, psychomotor, and affective objectives of…

  10. Carving a New Assessment Trail

    Science.gov (United States)

    Morriston, Terry

    2007-01-01

    TRAILS (Tool for Real-Time Assessment of Information Literacy Skills), is a free online test of student information-handling skills. It was formulated by the Institute for Library and Information Literacy Education and Kent State University Libraries. Based on the Ohio Academic Content Standards and the philosophy of Information Power, it assesses…

  11. Electronic Escape Trails for Firefighters

    Science.gov (United States)

    Jorgensen, Charles; Schipper, John; Betts, Bradley

    2008-01-01

    A proposed wireless-communication and data-processing system would exploit recent advances in radio-frequency identification devices (RFIDs) and software to establish information lifelines between firefighters in a burning building and a fire chief at a control station near but outside the building. The system would enable identification of trails that firefighters and others could follow to escape from the building, including identification of new trails should previously established trails become blocked. The system would include a transceiver unit and a computer at the control station, portable transceiver units carried by the firefighters in the building, and RFID tags that the firefighters would place at multiple locations as they move into and through the building (see figure). Each RFID tag, having a size of the order of a few centimeters, would include at least standard RFID circuitry and possibly sensors for measuring such other relevant environmental parameters as temperature, levels of light and sound, concentration of oxygen, concentrations of hazardous chemicals in smoke, and/or levels of nuclear radiation. The RFID tags would be activated and interrogated by the firefighters and control-station transceivers. Preferably, RFID tags would be configured to communicate with each other and with the firefighters units and the control station in an ordered sequence, with built-in redundancy. In a typical scenario, as firefighters moved through a building, they would scatter many RFID tags into smoke-obscured areas by use of a compressed-air gun. Alternatively or in addition, they would mark escape trails by dropping RFID tags at such points of interest as mantraps, hot spots, and trail waypoints. The RFID tags could be of different types, operating at different frequencies to identify their functions, and possibly responding by emitting audible beeps when activated by signals transmitted by transceiver units carried by nearby firefighters.

  12. Modeling of Unsteady Sheet Cavitation on Marine Propeller Blades

    Directory of Open Access Journals (Sweden)

    Spyros A. Kinnas

    2003-01-01

    Full Text Available Unsteady sheet cavitation is very common on marine propulsor blades. The authors summarize a lifting-surface and a surface-panel model to solve for the unsteady cavitating flow around a propeller that is subject to nonaxisymmetric inflow. The time-dependent extent and thickness of the cavity were determined by using an iterative method. The cavity detachment was determined by applying the smooth detachment criterion in an iterative manner. A nonzeroradius developed vortex cavity model was utilized at the tip of the blade, and the trailing wake geometry was determined using a fully unsteady wake-alignment process. Comparisons of predictions by the two models and measurements from several experiments are given.

  13. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-01

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

  15. 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.

  16. Design and Analysis of Bionic Cutting Blades Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Mo Li

    2015-01-01

    Full Text Available Praying mantis is one of the most efficient predators in insect world, which has a pair of powerful tools, two sharp and strong forelegs. Its femur and tibia are both armed with a double row of strong spines along their posterior edges which can firmly grasp the prey, when the femur and tibia fold on each other in capturing. These spines are so sharp that they can easily and quickly cut into the prey. The geometrical characteristic of the praying mantis’s foreleg, especially its tibia, has important reference value for the design of agricultural soil-cutting tools. Learning from the profile and arrangement of these spines, cutting blades with tooth profile were designed in this work. Two different sizes of tooth structure and arrangement were utilized in the design on the cutting edge. A conventional smooth-edge blade was used to compare with the bionic serrate-edge blades. To compare the working efficiency of conventional blade and bionic blades, 3D finite element simulation analysis and experimental measurement were operated in present work. Both the simulation and experimental results indicated that the bionic serrate-edge blades showed better performance in cutting efficiency.

  17. Steady flow and stability analyses of cavitation in finite blade count impeller; Yugen'yokusu no haneguruma ni shojiru cavitation no teijo nagare kaiseki to antei kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Horiguchi, H.; Tsujimoto, Y. [Osaka University, Osaka (Japan); Wahl, F. [SEP. division de SNECMA, (France); Watanabe, S. [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1999-08-25

    The seady flow and stability analyses of cavitation in flat plate cascades corresponding to 2, 3, 4 and 5 bladed impeller were carried out to find out all of the steady cavity patterns and destabilizing modes. For this purpose each blade is treated independently. In steady flow analysis the alternate blade cavitation was found only for impellers with even number of blades. It was shown that the alternate blade cavitation occurs since the local flow near the cavity closure reduces the angle of attack to the opposing blade when the cavity closure point approaches the leading edge of the opposing blade. For 2 or 4 bladed impeller, it was confirmed that there exists no additional destabilizing mode to those found in an analysis assuming inter-blade phase difference. It was shown that the modes with total cavity volume fluctuation depend on the inlet duct length while the modes without total cavity volume fluctuation are independent on the system. (author)

  18. Recreational trails as a source of negative impacts on the persistence of keystone species and facilitation.

    Science.gov (United States)

    Ballantyne, Mark; Pickering, Catherine Marina

    2015-08-15

    Hiking trails, which are among the most common forms of infrastructure created for nature-based tourism, can alter key ecological processes. Trails can damage plants that facilitate the establishment and growth of other species leading to changes in community and functional composition. This can be a particular concern in harsh alpine ecosystems where plant communities are often dominated by one or two keystone species that provide shelter to a suite of beneficiary species. We analysed how a hiking trail affects interspecific facilitation by a dominant trampling-sensitive nurse shrub in the highest National Park in Australia. First we assessed the effects of the trail on the abundance, size and density of the nurse shrub at different distances from the trail. We then compared species richness and composition between areas in, and out, of the nurse shrub's canopy at different distances from the trail. To better understand why some species may benefit from facilitation and any effects of the trail on the quality of facilitation we compared functional composition between quadrats using community trait weighted means calculated by combining plant composition with species functional traits (canopy height, leaf area, % dry weight of leaves and specific leaf area). The abundance, size and density of nurse shrubs was lower on the trail edges than further away, particularly on the leeward edge, where there was more bare ground and less shrub cover. There were differences in species richness, cover, composition and functional composition in and outside the nurse shrub canopy. The shrubs appeared to facilitate species with more competitive, but less stress tolerant traits (e.g. taller plants with leaves that were larger, had high specific leaf area and low dry matter content). However, despite reductions in nurse shrubs near the trail, where they do exist, they appear to provide the same 'quality' of facilitation as nurse shrubs further away. However, longer-term effects may

  19. 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

  20. 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....

  1. 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.

  2. 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)

  3. The impacts of trail infrastructure on vegetation and soils: Current literature and future directions.

    Science.gov (United States)

    Ballantyne, Mark; Pickering, Catherine Marina

    2015-12-01

    Reflecting the popularity of nature-based activities such as hiking and mountain biking, there are thousands of kilometres of recreational trails worldwide traversing a range of natural areas. These trails have environmental impacts on soils and vegetation, but where has there been research, what impacts have been found and how were they measured? Using a systematic quantitative literature review methodology, we assessed the impacts of trails on vegetation and soils, highlighting what is known, but also key knowledge gaps. Of the 59 original research papers identified on this topic that have been published in English language peer-reviewed academic journals, most were for research conducted in protected areas (71%), with few from developing countries (17%) or threatened ecosystems (14%). The research is concentrated in a few habitats and biodiversity hotspots, mainly temperate woodland, alpine grassland and Mediterranean habitats, often in the USA (32%) or Australia (20%). Most examined formal trails, with just 15% examining informal trails and 11% assessing both types. Nearly all papers report the results of observational surveys (90%), collecting quantitative data (66%) with 24% using geographic information systems. There was an emphasis on assessing trail impacts at a local scale, either on the trail itself and/or over short gradients away from the trail edge. Many assessed changes in composition and to some degree, structure, of vegetation and soils with the most common impacts documented including reduced vegetation cover, changes in plant species composition, trail widening, soil loss and soil compaction. There were 14 papers assessing how these local impacts can accumulate at the landscape scale. Few papers assessed differences in impacts among trails (7 papers), changes in impacts over time (4), species-specific responses (3) and only one assessed effects on plant community functioning. This review provides evidence that there are key research gaps

  4. Turbine blade with spar and shell

    Science.gov (United States)

    Davies, Daniel O.; Peterson, Ross H.

    2012-04-24

    A turbine blade with a spar and shell construction in which the spar and the shell are both secured within two platform halves. The spar and the shell each include outward extending ledges on the bottom ends that fit within grooves formed on the inner sides of the platform halves to secure the spar and the shell against radial movement when the two platform halves are joined. The shell is also secured to the spar by hooks extending from the shell that slide into grooves formed on the outer surface of the spar. The hooks form a serpentine flow cooling passage between the shell and the spar. The spar includes cooling holes on the lower end in the leading edge region to discharge cooling air supplied through the platform root and into the leading edge cooling channel.

  5. Wind Tunnel Evaluation of a Model Helicopter Main-Rotor Blade With Slotted Airfoils at the Tip

    Science.gov (United States)

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

    2001-01-01

    Data for rotors using unconventional airfoils are of interest to permit an evaluation of this technology's capability to meet the U.S. Army's need for increased helicopter mission effectiveness and improved safety and survivability. Thus, an experimental investigation was conducted in the Langley Transonic Dynamics Tunnel (TDT) to evaluate the effect of using slotted airfoils in the rotor blade tip region (85 to 100 percent radius) on rotor aerodynamic performance and loads. Four rotor configurations were tested in forward flight at advance ratios from 0.15 to 0.45 and in hover in-ground effect. The hover tip Mach number was 0.627, which is representative of a design point of 4000-ft geometric altitude and a temperature of 95 F. The baseline rotor configuration had a conventional single-element airfoil in the tip region. A second rotor configuration had a forward-slotted airfoil with a -6 deg slat, a third configuration had a forward-slotted airfoil with a -10 slat, and a fourth configuration had an aft-slotted airfoil with a 3 deg flap (trailing edge down). The results of this investigation indicate that the -6 deg slat configuration offers some performance and loads benefits over the other three configurations.

  6. Critical exponents for square lattice trails with a fixed number of vertices of degree 4

    International Nuclear Information System (INIS)

    We prove several previously conjectured results about the number of n-edge trails and n-edge embeddings of Eulerian graphs, each with a fixed number, k, of degree 4 vertices, in the lattice Z2. In particular, under the assumption that the relevant critical exponents exist, we prove that the difference between the critical exponent for closed trails (Eulerian graph embeddings) and that for self-avoiding circuits (polygons) is exactly k, the number of degree 4 vertices. Similarly, we prove that the difference between the critical exponent for either open trails or open Eulerian graph embeddings and that for self-avoiding walks is also k. These results are proved by establishing upper and lower bounds for the number of n-edge embeddings of closed (open) Eulerian graphs with k vertices of degree 4 in terms of the number of n-edge self-avoiding polygons (walks). The lower bounds are proved using a Kesten pattern theorem argument and the upper bounds are established by developing (based on a detailed case analysis) a method for removing vertices of degree 4 from an embedding by altering at most a constant (independent of n) number of vertices and edges of the embedding. The work presented here extends and improves the arguments first given in the work of Zhao and Lookman (1993 J. Phys. A: Math. Gen. 26 1067-76)

  7. Trails, Other, Trails, Published in 2007, 1:24000 (1in=2000ft) scale, Juab County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Trails, Other dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Other information as of 2007. It is described as 'Trails'....

  8. The Rim Trail at Pipe Spring National Monument, Arizona (pisp_trail)

    Data.gov (United States)

    National Park Service, Department of the Interior — This is an Arc/Info coverage consisting of 4 arcs representing The Rim Trail at Pipe Spring National Monument, Arizona. The Rim Trail was collected by a Trimble...

  9. 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...

  10. Road Expansion and Its Influence on Trail Sustainability in Bhutan

    Directory of Open Access Journals (Sweden)

    Taiichi Ito

    2011-12-01

    Full Text Available Bhutan was an inhabited wilderness until 1961, when road construction started after the closure of the Tibetan border. Since then, the road network has expanded from the Indian boarder, often tracing traditional trails. This has accelerated commerce as well as movement of people from India, benefitting both the Bhutanese and foreign tourists. At the same time, dependence on imported automobiles and fossil fuel has risen, and roadless areas have begun to shrink. This brought an inevitable loss of traditional environmental knowledge, such as the care of mules for packing, and reduction in physical and mental health among the Bhutanese. People who lost jobs as horsemen moved into towns to find jobs. Road extension is also a double-edged sword for visitors. It has resulted in shrinking trekking areas and loss of traditional culture, both of which have been sacrificed for easy access. Protected areas often function as fortifications against mechanical civilization. However, protected-area status or its zoning does not guarantee that an area will remain roadless where there is considerable resident population. An analysis in Jigme Dorji National Park showed the gradual retreat of trailheads and increasing dependence on automobiles among residents and trekkers. B. MacKaye, a regional planner in the Eastern United States, proposed using trails as a tool to control such mechanical civilization. His philosophy of regional planning suggests two measures; one is consolidated trailheads as dams, and the other is confinement of roads by levees, consisting of new trails and wilderness belts. According to case studies, the author proposed six options for coexistence of trails with roads.

  11. Trails at LANL - Public Meeting and Forum - July 26, 2016

    Energy Technology Data Exchange (ETDEWEB)

    Pava, Daniel Seth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-07-26

    These are the slides of a meeting about trails at Los Alamos National Laboratory. The meeting goals are the folllowing: to inform and educate citizens about LANL trails management issues that include resource protection, safety, security and trails etiquette; to explain how and why LANL trails can be closed and reopened; and to understand your concerns and ideas about LANL trails use.

  12. 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.

  13. Edge Matters

    DEFF Research Database (Denmark)

    Earon, Ofri

    2013-01-01

    building. The research explores and develops the architectural characteristics of correlations between the resident, the singular unit, the building and the given location at the edge zone. It approaches the edge zone of the urban house as a platform for dynamic interactions between these behaviours. The...... following text includes the first draft of the first two chapters: introduction and theory. The chapters are not written completely, and some parts are written only as headlines. These headlines and other comments are marked in red. The text is on working progress and far from being finished, but it will be...

  14. Beam Trail Tracking at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Nicklaus, Dennis J. [Fermilab; Carmichael, Linden Ralph [Fermilab; Neswold, Richard [Fermilab; Yuan, Zongwei [Fermilab

    2015-01-01

    We present a system for acquiring and sorting data from select devices depending on the destination of each particular beam pulse in the Fermilab accelerator chain. The 15 Hz beam that begins in the Fermilab ion source can be directed to a variety of additional accelerators, beam lines, beam dumps, and experiments. We have implemented a data acquisition system that senses the destination of each pulse and reads the appropriate beam intensity devices so that profiles of the beam can be stored and analysed for each type of beam trail. We envision utilizing this data long term to identify trends in the performance of the accelerators

  15. 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.

  16. Living edge

    DEFF Research Database (Denmark)

    Earon, Ofri

    2014-01-01

    “What is an edge? We can think about an edge as having been of two sorts. In one, it is a border. In the other, it is a boundary. A border is a zone of interaction where things meet and intersect. A boundary is a place where something ends” Architects and planners normally approach domestic borders...... the involved actors at the border. By doing so, the study underlines a forgotten, yet important, role of this edge zone – being a zone of commonality between the house and city, between indoors and outdoors, between the man at home and the man at the street. The city of Copenhagen promotes porous...... borders on the ground level, but there is a lack of recognition in the significance of communicative characters as well at the higher part of the edge. The city’s planning approach is “Consider urban life before urban space. Consider urban space before buildings” This urban strategy neglects the possible...

  17. 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...

  18. Edge Effects on Community and Social Structure of Northern Temperate Deciduous Forest Ants

    OpenAIRE

    Valerie S. Banschbach; Rebecca Yeamans; Ann Brunelle; Annie Gulka; Margaret Holmes

    2012-01-01

    Determining how ant communities are impacted by challenges from habitat fragmentation, such as edge effects, will help us understand how ants may be used as a bioindicator taxon. To assess the impacts of edge effects upon the ant community in a northern temperate deciduous forest, we studied edge and interior sites in Jericho, VT, USA. The edges we focused upon were created by recreational trails. We censused the ants at these sites for two consecutive growing seasons using pitfall traps and...

  19. Riding a Trail of Debris

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Figure 1 This image taken by NASA's Spitzer Space Telescope shows the comet Encke riding along its pebbly trail of debris (long diagonal line) between the orbits of Mars and Jupiter. This material actually encircles the solar system, following the path of Encke's orbit. Twin jets of material can also be seen shooting away from the comet in the short, fan-shaped emission, spreading horizontally from the comet. Encke, which orbits the Sun every 3.3 years, is well traveled. Having exhausted its supply of fine particles, it now leaves a long trail of larger more gravel-like debris, about one millimeter in size or greater. Every October, Earth passes through Encke's wake, resulting in the well-known Taurid meteor shower. This image was captured by Spitzer's multiband imaging photometer when Encke was 2.6 times farther away than Earth is from the Sun. It is the best yet mid-infrared view of the comet at this great distance. The data are helping astronomers understand how rotating comets eject particles as they circle the Sun.

  20. Energy saving through trail following in a marine snail

    OpenAIRE

    Davies, Mark S; Blackwell, Janine

    2007-01-01

    Most snails and slugs locomote over a layer of mucus and although the resultant mucus trail is expensive to produce, we show that this expense can be reduced by trail following. When tracking over fresh conspecific trails, the marine intertidal snail Littorina littorea (L.) produced only approximately 27% of the mucus laid by marker snails. When tracking over weathered trails, snails adjusted their mucus production to recreate a convex trail profile of similar shape and thickness to the trail...

  1. In-Trail Procedure (ITP) Algorithm Design

    Science.gov (United States)

    Munoz, Cesar A.; Siminiceanu, Radu I.

    2007-01-01

    The primary objective of this document is to provide a detailed description of the In-Trail Procedure (ITP) algorithm, which is part of the Airborne Traffic Situational Awareness In-Trail Procedure (ATSA-ITP) application. To this end, the document presents a high level description of the ITP Algorithm and a prototype implementation of this algorithm in the programming language C.

  2. Bradford routes to peace heritage trail

    OpenAIRE

    Chalcraft, Ben; Hadwen, Diane

    2013-01-01

    Mini-guide book to support a trail around BD1, exploring the City’s peace and social reform heritage through the built environment; content to be researched and delivered by young people and then ‘passed on’ by them to others in the community who follow the trail.

  3. 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.

  4. Critical exponents for square lattice trails with a fixed number of vertices of degree 4

    CERN Document Server

    James, E W

    2002-01-01

    We prove several previously conjectured results about the number of n-edge trails and n-edge embeddings of Eulerian graphs, each with a fixed number, k, of degree 4 vertices, in the lattice Z sup 2. In particular, under the assumption that the relevant critical exponents exist, we prove that the difference between the critical exponent for closed trails (Eulerian graph embeddings) and that for self-avoiding circuits (polygons) is exactly k, the number of degree 4 vertices. Similarly, we prove that the difference between the critical exponent for either open trails or open Eulerian graph embeddings and that for self-avoiding walks is also k. These results are proved by establishing upper and lower bounds for the number of n-edge embeddings of closed (open) Eulerian graphs with k vertices of degree 4 in terms of the number of n-edge self-avoiding polygons (walks). The lower bounds are proved using a Kesten pattern theorem argument and the upper bounds are established by developing (based on a detailed case anal...

  5. Ways of TPP and NPP powerful steam turbine blade erosion decreasing in low flow rate regimes

    International Nuclear Information System (INIS)

    A systematized approach to the problem of efficient cooling of flow passage and exhaust parts of TPP and NPP steam turbines and prevention of erosion wear of inlet and outlet edges of operating blades is presented. Methods for LP casing cooling and sources of erosion-hazard moisture as well as the main technological and design measures to decrease the erosion of blades are determined

  6. Improvement of propeller blades used for handling liquids containing fibrous solids

    Science.gov (United States)

    Bernauer, Jan; Wittekindt, Widu; Stark, Mathias

    1987-03-01

    The entrapment of long fibrous solids on the leading edge of axial centrifugal pump impeller blades was studied. These materials may increase the power drawn from the pump to the extent that, for example, a flood control pumping station may have to be shut down. Experiments studied the parameters fostering the entrapment of fibrous solids. A propeller blade eliminating entrapment was designed. The effectiveness of the design is demonstrated by experiments and field application.

  7. Numerical investigation of blade dynamic characteristics in an axial flow pump

    OpenAIRE

    Zhang Desheng; Pan Dazhi; Xu Yan; Shao Peipei; Wang Guotao

    2013-01-01

    The unsteady numerical simulation of fluid field and structural transient dynamic analysis of axial flow pump were carried out at three operating conditions based on fluid-structure interaction method. Numerical results show that the maximum equivalent stress of impeller occurs at the joint region of the impeller blade root and the hub, and the maximum deformation of impeller occurs at the tips of blade leading edges. The frequency-domain of the maximum equ...

  8. Energy efficient engine shroudless, hollow fan blade technology report

    Science.gov (United States)

    Michael, C. J.

    1981-01-01

    The Shroudless, Hollow Fan Blade Technology program was structured to support the design, fabrication, and subsequent evaluation of advanced hollow and shroudless blades for the Energy Efficient Engine fan component. Rockwell International was initially selected to produce hollow airfoil specimens employing the superplastic forming/diffusion bonding (SPF/DB) fabrication technique. Rockwell demonstrated that a titanium hollow structure could be fabricated utilizing SPF/DB manufacturing methods. However, some problems such as sharp internal cavity radii and unsatisfactory secondary bonding of the edge and root details prevented production of the required quantity of fatigue test specimens. Subsequently, TRW was selected to (1) produce hollow airfoil test specimens utilizing a laminate-core/hot isostatic press/diffusion bond approach, and (2) manufacture full-size hollow prototype fan blades utilizing the technology that evolved from the specimen fabrication effort. TRW established elements of blade design and defined laminate-core/hot isostatic press/diffusion bonding fabrication techniques to produce test specimens. This fabrication technology was utilized to produce full size hollow fan blades in which the HIP'ed parts were cambered/twisted/isothermally forged, finish machined, and delivered to Pratt & Whitney Aircraft and NASA for further evaluation.

  9. Design optimization of rotary tiller blades: a critical review

    Directory of Open Access Journals (Sweden)

    Subrata Kr Mandal

    2013-07-01

    Full Text Available Tillage is an operation performed to obtain a desirable soil structure for a seedbed or root bed. A granular structure is desirable to allow rapid infiltration and good retention of rainfall and to minimize resistance to root penetration. Rotavator (also called rotary tiller is a tractor operated cultivating implement that breaks or works the soil with the help of rotating blades. The use of rotavator is increasing due to its versatility in doing a good quality tillage job with minimum number of passes. The rotavator do simultaneous ploughing and harrowing in dry and optimum soil moisture in single operation. The blades are the main critical parts of a rotary tiller which are engaged with soil.  So, wearing takes places at the cutting edges of these blades due to high stresses are coming. In this context a lot of research on rotavator blade has been carried out in different parts of the world. This paper briefly reviews the work done so far on the rotary tillers’ blade design optimization and development.

  10. Numerical Analysis of Blade Geometry Generation Techniques for Centrifugal Compressors

    OpenAIRE

    Florin Iancu; John Trevino; Steven Sommer

    2007-01-01

    It is a known fact that machined impellers result in improved compressor performance compared to cast impellers of the same design. The performance improvements can be attributed to better surface finish, more accurate geometric definition (tighter dimensional tolerances), well-defined edges, and the lack of blade tip fillet on shrouded impellers. In addition, it has been observed through experimental investigations that the construction method of the impellers has an impact on performance. T...

  11. 'EMAGTRONIC', a portable tool to locate LP turbine blades endangered by stress corrosion cracking

    International Nuclear Information System (INIS)

    L.P. turbine last stage blades (material X 20 Cr 13) operating well within the moisture region require protection against water droplet erosion. To increase the resistance of the leading edge to droplet erosion, a flame hardening process at about 10000C is employed. In order to preclude stress corrosion cracking in this area, residual tensile surface stresses must be avoided. The new electromagnetic equipment gives quantifiable information regarding the residual stress state of the blades vane surface and can be used to check the blade manufacturing quality control and also for in-service inspection in power plants. (orig.)

  12. Numerical investigation of blade dynamic characteristics in an axial flow pump

    Directory of Open Access Journals (Sweden)

    Zhang Desheng

    2013-01-01

    Full Text Available The unsteady numerical simulation of fluid field and structural transient dynamic analysis of axial flow pump were carried out at three operating conditions based on fluid-structure interaction method. Numerical results show that the maximum equivalent stress of impeller occurs at the joint region of the impeller blade root and the hub, and the maximum deformation of impeller occurs at the tips of blade leading edges. The frequency-domain of the maximum equivalent stress and outlet pressure fluctuation of impeller are mainly affected by the impeller blade passing frequency.

  13. Effect of blade configuration, knife action, and intraocular pressure on keratotomy incision depth and shape.

    Science.gov (United States)

    Melles, G R; Wijdh, R H; Cost, B; Beekhuis, W H; Binder, P S; van Rij, G; Groot, K

    1993-07-01

    For the same diamond blade extension, uphill (centripetal) radial keratotomy incision direction achieves greater depth and consequently greater refractive effect than downhill (centrifugal) incisions. To determine which factors may account for this difference, two uphill and two downhill incisions were made with a double-edged diamond blade set to 90% central pachometry in 26 human donor eyes at 15 or 60 mm Hg. Uphill incisions made with the perpendicular blade had greater mean incision depth than downhill incisions made with the oblique blade at 15 mm Hg (83.6 +/- 3.9% and 68.2 +/- 5.2%) (p 0.1). The perpendicular blade edge created a straight, and the oblique edge an S- or J-shaped, histological incision configuration. Corneal profile pictures taken during each incision showed the knife to tilt opposite of the incision direction and to move at a constant angle to the limbal plane, producing a smaller optical clear zone (OCZ) in the posterior stroma than intended with uphill incisions. Greater refractive effect with uphill incisions may be explained by the perpendicular blade being more effective in incising corneal lamellae, and the creation of a smaller posterior OCZ. Intraocular pressure variations during surgery may affect achieved incision depth of downhill, but not of uphill, incisions. PMID:8339558

  14. Trail impacts and trail impact management related to ecotourism visitation at Torres del Paine National Park, Chile

    Science.gov (United States)

    Farrell, T.A.; Marion, J.L.

    2002-01-01

    Ecotourism and protected area visitation in Central and South America are largely dependent upon a relatively undisturbed quality of natural resources. However, visitation may impact vegetation, soil, water and wildlife resources, and degrade visitor facilities such as recreation sites and trails. Findings are reported from trail impact research conducted at Torres del Paine National Park in Patagonia, Chile. The frequency and magnitude of selected trail impacts and the relative effect of the amount of use, vegetation type, trail position and trail grade are investigated. Findings differed from previous studies in that amount of use was significantly related to both trail width increases and trail erosion. Management actions to minimize trail impacts are offered.

  15. 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.

  16. 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.

  17. 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.

  18. Snails and their trails: the multiple functions of trail-following in gastropods.

    Science.gov (United States)

    Ng, Terence P T; Saltin, Sara H; Davies, Mark S; Johannesson, Kerstin; Stafford, Richard; Williams, Gray A

    2013-08-01

    Snails are highly unusual among multicellular animals in that they move on a layer of costly mucus, leaving behind a trail that can be followed and utilized for various purposes by themselves or by other animals. Here we review more than 40 years of experimental and theoretical research to try to understand the ecological and evolutionary rationales for trail-following in gastropods. Data from over 30 genera are currently available, representing a broad taxonomic range living in both aquatic and terrestrial environments. The emerging picture is that the production of mucus trails, which initially was an adaptation to facilitate locomotion and/or habitat extension, has evolved to facilitate a multitude of additional functions. Trail-following supports homing behaviours, and provides simple mechanisms for self-organisation in groups of snails, promoting aggregation and thus relieving desiccation and predation pressures. In gastropods that copulate, trail-following is an important component in mate-searching, either as an alternative, or in addition to the release of water- or air-borne pheromones. In some species, this includes a capacity of males not only to identify trails of conspecifics but also to discriminate between trails laid by females and males. Notably, trail discrimination seems important as a pre-zygotic barrier to mating in some snail species. As production of a mucus trail is the most costly component of snail locomotion, it is also tempting to speculate that evolution has given rise to various ways to compensate for energy losses. Some snails, for example, increase energy intake by eating particles attached to the mucus of trails that they follow, whereas others save energy through reducing the production of their own mucus by moving over previously laid mucus trails. Trail-following to locate a prey item or a mate is also a way to save energy. While the rationale for trail-following in many cases appears clear, the basic mechanisms of trail

  19. Pheromone disruption of Argentine ant trail integrity.

    Science.gov (United States)

    Suckling, D M; Peck, R W; Manning, L M; Stringer, L D; Cappadonna, J; El-Sayed, A M

    2008-12-01

    Disruption of Argentine ant trail following and reduced ability to forage (measured by bait location success) was achieved after presentation of an oversupply of trail pheromone, (Z)-9-hexadecenal. Experiments tested single pheromone point sources and dispersion of a formulation in small field plots. Ant walking behavior was recorded and digitized by using video tracking, before and after presentation of trail pheromone. Ants showed changes in three parameters within seconds of treatment: (1) Ants on trails normally showed a unimodal frequency distribution of walking track angles, but this pattern disappeared after presentation of the trail pheromone; (2) ants showed initial high trail integrity on a range of untreated substrates from painted walls to wooden or concrete floors, but this was significantly reduced following presentation of a point source of pheromone; (3) the number of ants in the pheromone-treated area increased over time, as recruitment apparently exceeded departures. To test trail disruption in small outdoor plots, the trail pheromone was formulated with carnuba wax-coated quartz laboratory sand (1 g quartz sand/0.2 g wax/1 mg pheromone). The pheromone formulation, with a half-life of 30 h, was applied by rotary spreader at four rates (0, 2.5, 7.5, and 25 mg pheromone/m(2)) to 1- and 4-m(2) plots in Volcanoes National Park, Hawaii. Ant counts at bait cards in treated plots were significantly reduced compared to controls on the day of treatment, and there was a significant reduction in ant foraging for 2 days. These results show that trail pheromone disruption of Argentine ants is possible, but a much more durable formulation is needed before nest-level impacts can be expected. PMID:19034574

  20. TRIPPy: Python-based Trailed Source Photometry

    Science.gov (United States)

    Fraser, Wesley C.; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michael E.; Pike, Rosemary E.; Kavelaars, JJ; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-05-01

    TRIPPy (TRailed Image Photometry in Python) uses a pill-shaped aperture, a rectangle described by three parameters (trail length, angle, and radius) to improve photometry of moving sources over that done with circular apertures. It can generate accurate model and trailed point-spread functions from stationary background sources in sidereally tracked images. Appropriate aperture correction provides accurate, unbiased flux measurement. TRIPPy requires numpy, scipy, matplotlib, Astropy (ascl:1304.002), and stsci.numdisplay; emcee (ascl:1303.002) and SExtractor (ascl:1010.064) are optional.

  1. Audit trails in an online accountability system

    International Nuclear Information System (INIS)

    The Safeguards Accountability Network (SAN) is an online computer system that was developed by Rockwell International to track the accounting and processing of nuclear materials from the time it arrives at Rocky Flats Plant through its life cycle. A major contributor to the success of SAN is the use of audit trails. They have proven to be invaluable for the management and safeguarding of these sensitive materials at Rocky Flats. Producing effective audit trails requires the recording of all pertinent transactions and the capability to access and report the information in a timely fashion. This paper discusses the implementation and application of these audit trails on the Rocky Flats SAN system

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

    Science.gov (United States)

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

    2015-04-01

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

  3. Surface TRAIL decoy receptor-4 expression is correlated with TRAIL resistance in MCF7 breast cancer cells

    International Nuclear Information System (INIS)

    Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) selectively induces apoptosis in cancer cells but not in normal cells. Despite this promising feature, TRAIL resistance observed in cancer cells seriously challenged the use of TRAIL as a death ligand in gene therapy. The current dispute concerns whether or not TRAIL receptor expression pattern is the primary determinant of TRAIL sensitivity in cancer cells. This study investigates TRAIL receptor expression pattern and its connection to TRAIL resistance in breast cancer cells. In addition, a DcR2 siRNA approach and a complementary gene therapy modality involving IKK inhibition (AdIKKβKA) were also tested to verify if these approaches could sensitize MCF7 breast cancer cells to adenovirus delivery of TRAIL (Ad5hTRAIL). TRAIL sensitivity assays were conducted using Molecular Probe's Live/Dead Cellular Viability/Cytotoxicity Kit following the infection of breast cancer cells with Ad5hTRAIL. The molecular mechanism of TRAIL induced cell death under the setting of IKK inhibition was revealed by Annexin V binding. Novel quantitative Real Time RT-PCR and flow cytometry analysis were performed to disclose TRAIL receptor composition in breast cancer cells. MCF7 but not MDA-MB-231 breast cancer cells displayed strong resistance to adenovirus delivery of TRAIL. Only the combinatorial use of Ad5hTRAIL and AdIKKβKA infection sensitized MCF7 breast cancer cells to TRAIL induced cell death. Moreover, novel quantitative Real Time RT-PCR assays suggested that while the level of TRAIL Decoy Receptor-4 (TRAIL-R4) expression was the highest in MCF7 cells, it was the lowest TRAIL receptor expressed in MDA-MB-231 cells. In addition, conventional flow cytometry analysis demonstrated that TRAIL resistant MCF7 cells exhibited substantial levels of TRAIL-R4 expression but not TRAIL decoy receptor-3 (TRAIL-R3) on surface. On the contrary, TRAIL sensitive MDA-MB-231 cells displayed very low levels of surface TRAIL-R4

  4. Surface TRAIL decoy receptor-4 expression is correlated with TRAIL resistance in MCF7 breast cancer cells

    Directory of Open Access Journals (Sweden)

    Aydin Cigdem

    2005-05-01

    Full Text Available Abstract Background Tumor Necrosis Factor (TNF-Related Apoptosis-Inducing Ligand (TRAIL selectively induces apoptosis in cancer cells but not in normal cells. Despite this promising feature, TRAIL resistance observed in cancer cells seriously challenged the use of TRAIL as a death ligand in gene therapy. The current dispute concerns whether or not TRAIL receptor expression pattern is the primary determinant of TRAIL sensitivity in cancer cells. This study investigates TRAIL receptor expression pattern and its connection to TRAIL resistance in breast cancer cells. In addition, a DcR2 siRNA approach and a complementary gene therapy modality involving IKK inhibition (AdIKKβKA were also tested to verify if these approaches could sensitize MCF7 breast cancer cells to adenovirus delivery of TRAIL (Ad5hTRAIL. Methods TRAIL sensitivity assays were conducted using Molecular Probe's Live/Dead Cellular Viability/Cytotoxicity Kit following the infection of breast cancer cells with Ad5hTRAIL. The molecular mechanism of TRAIL induced cell death under the setting of IKK inhibition was revealed by Annexin V binding. Novel quantitative Real Time RT-PCR and flow cytometry analysis were performed to disclose TRAIL receptor composition in breast cancer cells. Results MCF7 but not MDA-MB-231 breast cancer cells displayed strong resistance to adenovirus delivery of TRAIL. Only the combinatorial use of Ad5hTRAIL and AdIKKβKA infection sensitized MCF7 breast cancer cells to TRAIL induced cell death. Moreover, novel quantitative Real Time RT-PCR assays suggested that while the level of TRAIL Decoy Receptor-4 (TRAIL-R4 expression was the highest in MCF7 cells, it was the lowest TRAIL receptor expressed in MDA-MB-231 cells. In addition, conventional flow cytometry analysis demonstrated that TRAIL resistant MCF7 cells exhibited substantial levels of TRAIL-R4 expression but not TRAIL decoy receptor-3 (TRAIL-R3 on surface. On the contrary, TRAIL sensitive MDA-MB-231 cells

  5. TRAIL-induced apoptosis and expression of death receptor TRAIL-R1 and TRAIL-R2 in bladder cancer cells.

    Directory of Open Access Journals (Sweden)

    Zenon P Czuba

    2010-05-01

    Full Text Available Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L is a member of TNF superfamily able to induce programmed death in cancer cells with no toxicity against normal tissues. TRAIL mediate apoptosis follows binding to the two death receptors, TRAIL-R1 (DR4 and/or TRAIL-R2 (DR5. In this study we investigated the cytotoxic and apoptotic effect of TRAIL on bladder cancer cells and the expression of death receptor TRAIL-R1 and TRAIL-R2 on the surface of these cancer cells. Three human bladder transitional cancer cell (TCC lines - SW780, 647V and T24 were tested for TRAIL sensitivity. The bladder cancer cells were incubated with human soluble recombinant TRAIL. Cytotoxicity was measured by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-dimethyltetrazolium bromide and LDH (lactate dyhydrogenase assays. Apoptosis was detected by flow cytometry with annexin V-FITC/propidium iodide and by fluorescence microscopy with Hoechst 33342/annexin V-FITC/Ethidium Homodimer. The cell surface expression of TRAIL death receptors on bladder cancer were determined using flow cytometry with phycoerythrin-conjugated monoclonal anti-human TRAIL-R1 and TRAIL-R2. Our investigations confirmed that SW780 cells were sensitive to TRAIL, and two other bladder cancer cell lines, 647V and T24, were resistant to TRAIL induced apoptosis. We therefore examined the expression of TRAIL death receptors on bladder cancer cell surfaces. We showed decreased expression of TRAIL-R2 receptor in TRAIL-resistant bladder cancer cells and increased expression of this death receptor in TRAIL-sensitive SW780 cells. The expression of TRAILR1 receptor was similar in all bladder cancer cell lines. TRAIL is one of the promising candidates for cancer therapeutics. However, some cancer cells are resistant to TRAIL-mediated apoptosis. It is therefore important to overcome this resistance for the clinical use of TRAIL in cancer therapy. TRAIL death receptors are attractive therapeutic targets in

  6. Losing your edge: climate change and the conservation value of range-edge populations.

    Science.gov (United States)

    Rehm, Evan M; Olivas, Paulo; Stroud, James; Feeley, Kenneth J

    2015-10-01

    Populations occurring at species' range edges can be locally adapted to unique environmental conditions. From a species' perspective, range-edge environments generally have higher severity and frequency of extreme climatic events relative to the range core. Under future climates, extreme climatic events are predicted to become increasingly important in defining species' distributions. Therefore, range-edge genotypes that are better adapted to extreme climates relative to core populations may be essential to species' persistence during periods of rapid climate change. We use relatively simple conceptual models to highlight the importance of locally adapted range-edge populations (leading and trailing edges) for determining the ability of species to persist under future climates. Using trees as an example, we show how locally adapted populations at species' range edges may expand under future climate change and become more common relative to range-core populations. We also highlight how large-scale habitat destruction occurring in some geographic areas where many species range edge converge, such as biome boundaries and ecotones (e.g., the arc of deforestation along the rainforest-cerrado ecotone in the southern Amazonia), can have major implications for global biodiversity. As climate changes, range-edge populations will play key roles in helping species to maintain or expand their geographic distributions. The loss of these locally adapted range-edge populations through anthropogenic disturbance is therefore hypothesized to reduce the ability of species to persist in the face of rapid future climate change. PMID:26664681

  7. Influence of rotor blade tip shape on tip vortex shedding - An unsteady, inviscid analysis

    Science.gov (United States)

    Maskew, B.

    1980-01-01

    An unsteady potential flow panel method is described based on a time-stepping procedure and using planar quadrilateral panels to represent the surface of thick blades. Each panel has a constant source and doublet distribution and a central control point where an internal Dirichlet boundary condition is applied. The method includes detail paneling around the tip edge and offers the facility of prescribing a tip-edge separation. Preliminary results are shown for four blade tip shapes which are treated as semi-span wings oscillating in pitch about a mean angle of attack of 6 deg. Further work is planned for the wake model before proceeding to higher angles of attack.

  8. 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)

  9. Minnesota State Park Trails and Roads

    Data.gov (United States)

    Minnesota Department of Natural Resources — This shapefile covers the trails in the State of Minnesota Parks, Recreation Areas, and Waysides as designated through legislation and recognized by the Department...

  10. Trails, Other, This would include horse trails, ATV Trails & cross country ski trails., Published in 2012, Not Applicable scale, Chippewa County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Trails, Other dataset, published at Not Applicable scale, was produced all or in part from Field Observation information as of 2012. It is described as 'This...

  11. US Forest Service National Forest System Trails

    Data.gov (United States)

    US Forest Service, Department of Agriculture — A map service on the world wide web that depicts National Forest Service trails that have been approved for publication. This service is used internally and...

  12. 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.

  13. Collaborative trails in e-learning environments

    OpenAIRE

    Keenoy, K.; Levene, Mark; Freitas, Sara; Emans, B.; Schoonenboom, J.; Jones, A.; Brasher, A.; Waycott, J.; Turcsanyi-Szabo, M.; Bodnar, E.; Pernin, J.P.; Eyssautier, C.; Montandon, L.

    2004-01-01

    This deliverable focuses on collaboration within groups of learners, and hence collaborative trails. We begin by reviewing the theoretical background to collaborative learning and looking at the kinds of support that computers can give to groups of learners working collaboratively, and then look more deeply at some of the issues in designing environments to support collaborative learning trails and at tools and techniques, including collaborative filtering, that can be used for analysing coll...

  14. Turbine Airfoil Leading Edge Film Cooling Bibliography: 1972–1998

    OpenAIRE

    Kercher, D. M.

    2000-01-01

    Film cooling for turbine airfoil leading edges has been a common practice for at least 35 years as turbine inlet gas temperatures and pressures have continually increased along with cooling air temperatures for higher engine cycle efficiency. With substantial engine cycle performance improvements from higher gas temperatures, it has become increasingly necessary to film cool nozzle and rotor blade leading edges since external heat transfer coefficients and thus heat load are the highest in th...

  15. 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%.

  16. 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.

  17. 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.

  18. Expression of TRAIL-splice variants in gastric carcinomas: identification of TRAIL-γ as a prognostic marker

    International Nuclear Information System (INIS)

    TNF-related apoptosis inducing ligand (TRAIL) belongs to the TNF-superfamily that induces apoptotic cell death in a wide range of neoplastic cells in vivo as well as in vitro. We identified two alternative TRAIL-splice variants, i.e. TRAIL-β and TRAIL-γ that are characterized by the loss of their proapoptotic properties. Herein, we investigated the expression and the prognostic values of the TRAIL-splice variants in gastric carcinomas. Real time PCR for amplification of the TRAIL-splice variants was performed in tumour tissue specimens and corresponding normal tissues of 41 consecutive patients with gastric carcinoma. Differences on mRNA-expression levels of the TRAIL-isoforms were compared to histo-pathological variables and correlated with survival data. All three TRAIL-splice variants could be detected in both non-malignant and malignant tissues, irrespective of their histological staging, grading or tumour types. However, TRAIL-β exhibited a higher expression in normal gastric tissue. The proapoptotic TRAIL-α expression was increased in gastric carcinomas when compared to TRAIL-β and TRAIL-γ. In addition, overexpression of TRAIL-γ was associated with a significant higher survival rate. This is the first study that investigated the expression of TRAIL-splice variants in gastric carcinoma tissue samples. Thus, we provide first data that indicate a prognostic value for TRAIL-γ overexpression in this tumour entity

  19. Design and Evaluation of a Low-Noise Helicopter Blade

    Science.gov (United States)

    Kondo, Natsuki; Tsujiuchi, Tomoka; Murashige, Atsushi; Nishimura, Hiroki; Aoki, Makoto; Tsuchihashi, Akihiko; Yamakawa, Eiichi; Aoyama, Takashi; Saito, Shigeru

    A low-noise helicopter blade, AT1, was designed with the concept of reducing noise without the drop of rotor performance. In the concept, High-Speed Impulsive (HSI) noise is reduced by applying a thin airfoil in the tip region and a dog-tooth like extension in the leading-edge of the tip region. Blade-Vortex Interaction (BVI) noise is reduced by applying the extension and a strong taper near the tip end. The stall angle of the blade is increased by the effect of the vortex generated from the leading-edge extension. As a result, the drop of rotor performance caused by the thin airfoil and the reduction of rotor rotational speed is recovered. The low-noise characteristics and the performance of AT1 were evaluated by a model rotor test conducted at Deutsch Niederländischer Windkanal (DNW). It is shown that AT1 reduces HSI noise and BVI noise and has good performance in forward flight conditions. However, the improvement of performance in high-lift conditions still remains as a future problem.

  20. Nature Trails, Braille Trails, Foot Paths, Fragrance Gardens, Touch Museums for the Blind; Policy Statement.

    Science.gov (United States)

    American Foundation for the Blind, New York, NY.

    The policy statement by the American Foundation for the Blind deals with nature trails, braille trails, foot paths, fragrance gardens, and touch museums for the blind. It is stated that the foundation approves of services such as provision of tape recorded guides and planting of fragrant shrubs which would benefit all users while recognizing…

  1. CFD computations of wind turbine blade loads during standstill operation KNOW-BLADE, Task 3.1 report

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, N.N.; Johansen, J.; Conway, S.

    2004-06-01

    Two rotors blades are computed during standstill conditions, using two different Navier-Stokes solvers EDGE and EllipSys3D. Both steady and transient linear {kappa} - {omega} RANS turbulence models are applied, along with steady non-linear RANS and transient DES simulations. The STORK 5.0 WPX blade is computed a three different tip pitch angles, 0, 26 and 50 degrees tip pitch angle, while the NREL Phase-VI blade is computed at 90 degrees tip pitch angle. Generally the CFD codes reproduce the measured trends quite well and the two involved CFD codes give very similar results. The discrepancies observed can be explained by the difference in the applied turbulence models and the fact that the results from one of the solvers are presented as instantaneous values instead of averaged values. The comparison of steady and transient RANS results show that the gain of using time true computations are very limited for this case, with respect to mean quantities. The same can be said for the RANS/DES comparison performed for the NREL rotor, even though the DES computation shows improved agreement at the tip and root sections. Finally, it is shown that the DES methodology provides a much more physical representation of the heavily stalled part of the flow over blades at high angles of attack. (au)

  2. Experimental Study of the Effects of Blade Treatments on the Tip Vortex Characteristics.

    Science.gov (United States)

    Klimchenko, Vera

    2015-11-01

    The current study investigates the effects of blade tip treatments on the characteristics of a wind turbine blade tip vortex. Three blade tip shapes including a blunt edge, leading edge comb, and a winglet were designed and tested in a low speed wind tunnel. The rotor with a blunt edge was considered to be a baseline case corresponding to an untreated blade tip. The leading-edge comb rotor was designed with leading edge tubercles extending from the tip of the blade inward, 6 percent of rotor diameter. The winglet located at the tip of the winglet rotor had a cant angle of 45 degrees. The wind turbine operated at a tip speed ratio of 5 and a tip Reynolds number of 14,000. The tip treatments were intended to weaken the tip vortices by encouraging dissipation (leading edge comb) or promoting the formation of weaker vortices (winglet). Time-resolved and phase-averaged PIV was used to measure the velocity field behind the rotor. The time-averaged velocity field was subtracted from the phase-averaged velocity field to isolate the time-varying components of the flow. The vorticity of the phase-averaged time-varying field was calculated, and the tip vortices were identified using a vortex identification method. Vortex characteristics such as core radius and vortex strength were calculated and compared for the three rotors. The analysis of the vorticity showed that the winglet rotor had weaker tip vortices with a larger core radius, while the serrated tip rotor had strong tip vortices with the same core radius as the baseline case.

  3. Study on the influence of back blade shape on the wear characteristics of centrifugal slurry pump

    Science.gov (United States)

    Cai, X.; Zhou, S. P.; Li, S.

    2016-05-01

    CFX particle inhomogeneous model was introduced for the mechanism analysis of a centrifugal slurry pump which is equipped with back blades on impeller shrouds. Combining with the total efficiency correction, the simulation showed good prediction accuracy of external characteristics results compared with the experimental values. Vorticity and Q-Criterion were chosen as the variables to illustrate the abrasion morphology and wear mechanism by contrasting simulation result with worn impeller in engineering. The analysis showed that the large vorticity intensity areas are distributed at the edge of impeller shroud and intensively behind the back blades. Moreover, the vorticity scattered on suction surface of back blade shows the largest intensity. The contour of Q-Criterion demonstrated that the swirl scale in front cavity is obviously larger than that in back cavity. The distribution of vorticity on both front and back shrouds can reasonably explain the impeller wear characteristics. Finally, the forward curved back blade proved to be excellence performance in vorticity distribution.

  4. Effects of blade number on hydrodynamic force perturbation on impeller of voute type centrifugal pump

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Yutaka; Kikuyama, Koji; Maeda, Takao (Nagoya Univ., Faculty of Engineering, Nagoya, (Japan))

    1989-08-25

    Pressures in exit volute, hydrodynamic force perturbations and fluctuating pressure on a three-blade centrifugal impeller, were measured. Comparison of the forces between the three-and seven-blade impellers was made and the effects of the blade numbers on the hydrodynamic force were clarified. When an interval between the impeller outlet and the volute tongue is large, abrupt fluctuations, which are shown in pressures in exit volute at near the tonge, are relieved in the impeller outlet pressure. In the impeller channel, the amplitude of synchronous pressure fluctuation becomes large at near the outlet of impeller channel and the impeller front-edge. In comparison with the seven-blade impeller (normal blade number), there are few differences in the hydrodynamic force exerted on one blade. However, hydrodynamic force on the three-blade impeller exhibits a very large fluctuation. This is due to the fact that synchronous pressure fluctuation in the impeller exhibits a large fluctuation in lower component. 11 refs., 11 figs.

  5. Influence of blade outlet angle on performance of low-specific-speed centrifugal pump

    Science.gov (United States)

    Cui, Baoling; Wang, Canfei; Zhu, Zuchao; Jin, Yingzi

    2013-04-01

    In order to analyze the influence of blade outlet angle on inner flow field and performance of low-specific-speed centrifugal pump, the flow field in the pump with different blade outlet angles 32.5° and 39° was numerically calculated. The external performance experiment was also carried out on the pump. Based on SIMPLEC algorithm, time-average N-S equation and the rectified k-ɛ turbulent model were adopted during the process of computation. The distributions of velocity and pressure in pumps with different blade outlet angles were obtained by calculation. The numerical results show that backflow areas exist in the two impellers, while the inner flow has a little improvement in the impeller with larger blade outlet angle. Blade outlet angle has a certain influence on the static pressure near the long-blade leading edge and tongue, but it has little influence on the distribution of static pressure in the passages of impeller. The experiment results show that the low-specific-speed centrifugal pump with larger blade outlet angle has better hydraulic performance.

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

    Science.gov (United States)

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

    2015-09-01

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

  7. On the Nonlinear Structural Analysis of Wind Turbine Blades using Reduced Degree-of-Freedom Models

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Larsen, Jesper Winther; Nielsen, Søren R.K.

    2008-01-01

    Wind turbine blades are increasing in magnitude without a proportional increase of stiffness for which reason geometrical and inertial nonlinearities become increasingly important. Often these effects are analysed using a nonlinear truncated expansion in undamped fixed base mode shapes of a blade......, modelling geometrical and inertial nonlinear couplings in the fundamental flap and edge direction. The purpose of this article is to examine the applicability of such a reduced-degree-of-freedom model in predicting the nonlinear response and stability of a blade by comparison to a full model based on a...... nonlinear co-rotating FE formulation. By use of the reduced-degree-of-freedom model it is shown that under strong resonance excitation of the fundamental flap or edge modes, significant energy is transferred to higher modes due to parametric or nonlinear coupling terms, which influence the response and...

  8. TRIPPy: Trailed Image Photometry in Python

    Science.gov (United States)

    Fraser, Wesley; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michaël; Pike, Rosemary E.; Kavelaars, J. J.; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-06-01

    Photometry of moving sources typically suffers from a reduced signal-to-noise ratio (S/N) or flux measurements biased to incorrect low values through the use of circular apertures. To address this issue, we present the software package, TRIPPy: TRailed Image Photometry in Python. TRIPPy introduces the pill aperture, which is the natural extension of the circular aperture appropriate for linearly trailed sources. The pill shape is a rectangle with two semicircular end-caps and is described by three parameters, the trail length and angle, and the radius. The TRIPPy software package also includes a new technique to generate accurate model point-spread functions (PSFs) and trailed PSFs (TSFs) from stationary background sources in sidereally tracked images. The TSF is merely the convolution of the model PSF, which consists of a moffat profile, and super-sampled lookup table. From the TSF, accurate pill aperture corrections can be estimated as a function of pill radius with an accuracy of 10 mmag for highly trailed sources. Analogous to the use of small circular apertures and associated aperture corrections, small radius pill apertures can be used to preserve S/Ns of low flux sources, with appropriate aperture correction applied to provide an accurate, unbiased flux measurement at all S/Ns.

  9. The Role of the Pattern Edge in Goldfish Visual Motion Detection

    OpenAIRE

    Kim, Sun-Hee; Jung, Chang-Sub

    2010-01-01

    To understand the function of edges in perception of moving objects, we defined four questions to answer. Is the focus point in visual motion detection of a moving object: (1) the body or the edge of the object, (2) the leading edge or trailing edge of the object, (3) different in scotopic, mesopic and photopic luminance levels, or (4) different for colored objects? We measured the Optomotor Response (OMR) and Edge Triggering Response (ETR) of goldfish. We used a square and sine wave patterns...

  10. 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.

  11. Manipulation of upstream rotor leading edge vortex and its effects on counter rotating propeller noise

    Science.gov (United States)

    Squires, Becky

    1993-01-01

    The leading edge vortex of a counter rotating propeller (CRP) model was altered by using shrouds and by turning the upstream rotors to a forward sweep configuration. Performance, flow, and acoustic data were used to determine the effect of vortex impingement on the noise signature of the CRP system. Forward sweep was found to eliminate the leading edge vortex of the upstream blades. Removal of the vortex had little effect on the tone noise at the forward and rear blade passing frequencies (BPF's) but significantly altered both the sound pressure level and directivity of the interaction tone which occurs at the sum of the two BPF's. A separate manipulation of the leading edge vortex performed by installing shrouds of various inlet length on the CRP verified that diverting the vortex path increases the noise level of the interaction tone. An unexpected link has been established between the interaction tone and the leading edge vortex-blade interaction phenomenon.

  12. Effects of outlet blade angle of centrifugal pump on the pump performance under air-water two-phase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Minemura, Kiyoshi; Kinoshita, Katsuhiko [Nagoya Univ. (Japan). School of Informatics and Sciences; Ihara, Masaru; Furukawa, Hironori; Egashira, Kazuyuki [Japan National Oil Corp., Chiba (Japan). Petroleum Engineering Lab.

    1995-12-31

    To establish the optimum design parameters of offshore oil well centrifugal pumps, which should deliver crude oil containing a large amount of gas, various shapes of pump impeller with different outlet blade angles, locations of leading-edge and numbers of impeller blades as the design parameters were tested with various rotating speeds and suction pressures under air-water two-phase flow conditions. The greater the outlet blade angle, the less the degradation of the pump performance becomes, showing the optimum blade angle approximately equals to 90{degree}.

  13. Method to improve the blade tip-timing accuracy of fiber bundle sensor under varying tip clearance

    Science.gov (United States)

    Duan, Fajie; Zhang, Jilong; Jiang, Jiajia; Guo, Haotian; Ye, Dechao

    2016-01-01

    Blade vibration measurement based on the blade tip-timing method has become an industry-standard procedure. Fiber bundle sensors are widely used for tip-timing measurement. However, the variation of clearance between the sensor and the blade will bring a tip-timing error to fiber bundle sensors due to the change in signal amplitude. This article presents methods based on software and hardware to reduce the error caused by the tip clearance change. The software method utilizes both the rising and falling edges of the tip-timing signal to determine the blade arrival time, and a calibration process suitable for asymmetric tip-timing signals is presented. The hardware method uses an automatic gain control circuit to stabilize the signal amplitude. Experiments are conducted and the results prove that both methods can effectively reduce the impact of tip clearance variation on the blade tip-timing and improve the accuracy of measurements.

  14. Therapeutic applications of TRAIL receptor agonists in cancer and beyond.

    Science.gov (United States)

    Amarante-Mendes, Gustavo P; Griffith, Thomas S

    2015-11-01

    TRAIL/Apo-2L is a member of the TNF superfamily first described as an apoptosis-inducing cytokine in 1995. Similar to TNF and Fas ligand, TRAIL induces apoptosis in caspase-dependent manner following TRAIL death receptor trimerization. Because tumor cells were shown to be particularly sensitive to this cytokine while normal cells/tissues proved to be resistant along with being able to synthesize and release TRAIL, it was rapidly appreciated that TRAIL likely served as one of our major physiologic weapons against cancer. In line with this, a number of research laboratories and pharmaceutical companies have attempted to exploit the ability of TRAIL to kill cancer cells by developing recombinant forms of TRAIL or TRAIL receptor agonists (e.g., receptor-specific mAb) for therapeutic purposes. In this review article we will describe the biochemical pathways used by TRAIL to induce different cell death programs. We will also summarize the clinical trials related to this pathway and discuss possible novel uses of TRAIL-related therapies. In recent years, the physiological importance of TRAIL has expanded beyond being a tumoricidal molecule to one critical for a number of clinical settings - ranging from infectious disease and autoimmunity to cardiovascular anomalies. We will also highlight some of these conditions where modulation of the TRAIL/TRAIL receptor system may be targeted in the future. PMID:26343199

  15. 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.

  16. 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

  17. 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

  18. Integrated approach for stress based lifing of aero gas turbine blades

    Science.gov (United States)

    Abu, Abdullahi Obonyegba

    In order to analyse the turbine blade life, the damage due to the combined thermal and mechanical loads should be adequately accounted for. This is more challenging when detailed component geometry is limited. Therefore, a compromise between the level of geometric detail and the complexity of the lifing method to be implemented would be necessary. This research focuses on how the life assessment of aero engine turbine blades can be done, considering the balance between available design inputs and adequate level of fidelity. Accordingly, the thesis contributes to developing a generic turbine blade lifing method that is based on the engine thermodynamic cycle; as well as integrating critical design/technological factors and operational parameters that influence the aero engine blade life. To this end, thermo-mechanical fatigue was identified as the critical damage phenomenon driving the life of the turbine blade.. The developed approach integrates software tools and numerical models created using the minimum design information typically available at the early design stages. Using finite element analysis of an idealised blade geometry, the approach captures relevant impacts of thermal gradients and thermal stresses that contribute to the thermo-mechanical fatigue damage on the gas turbine blade. The blade life is evaluated using the Neu/Sehitoglu thermo-mechanical fatigue model that considers damage accumulation due to fatigue, oxidation, and creep. The leading edge is examined as a critical part of the blade to estimate the damage severity for different design factors and operational parameters. The outputs of the research can be used to better understand how the environment and the operating conditions of the aircraft affect the blade life consumption and therefore what is the impact on the maintenance cost and the availability of the propulsion system. This research also finds that the environmental (oxidation) effect drives the blade life and the blade coolant

  19. 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.

  20. 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.

  1. Study of Wear of Pitched Blade Impellers in a Solid-Liquid Suspension

    Directory of Open Access Journals (Sweden)

    I. Fořt

    2003-01-01

    Full Text Available A study was made of the erosion wear of the blades of pitched blade impellers in a suspension of silicious sand (CV= 5 %, d=0.325 mm, degree of hardness "7.5" in water under a turbulent flow regime of agitated charge when complete homogeneity of the suspension was achieved. Two aims of the study were defined: the dependence of the rate of the erosion process of the impeller blades on impeller frequency of revolution and on the size of the mixing equipment. Experiments were carried out on pilot plant mixing equipment of two sizes (geometrically similar made of stainless steel (diameters of cylindrical vessels T1 = 200 mm and T2 = 300 mm, diameters of impellers D1 = 100 mm and D2= 66. 7 mm, impeller off bottom clearances h1 = 100 mm and h2= 66. 7 mm, respectively equipped with four radial baffles (width b1 = 30 mm, b2 =20 mm, respectively and an impeller with four inclined plane blades (pitch angle α =30°, 45°, relative blade with W/D = 0.2 made of rolled brass (Brinnel hardness 40-50 BM always pumping the liquid downwards towards the float vessel bottom. The wear of the impeller was described by an analytical approximation in exponential form with two parameters (the wear rate constant k and the geometrical parameters of the worn blade C calculated by the least squares method from the experimentally found profile of the worn leading edge of the impeller blades. While the wear rate constant exhibits a monotonous dependence on the pitch angle only, the geometric parameter is dependent both on the pitch angle and in linear form on the impeller tip speed. Thus in the procedure for scaling up the rate of erosion wear of the pitched blade impellers in a suspension of higher solid particle hardness, the decision process parameters are the impeller blade pitch angle and the impeller tip speed.

  2. Honeymoon Trail at Pipe Spring National Monument, Arizona (honeytrl)

    Data.gov (United States)

    National Park Service, Department of the Interior — This is an Arc/Info coverage consisting of 1 arc that represents the Honeymoon Trail inside of Pipe Spring National Monument, Arizona. The Honeymoon Trail was...

  3. The Trail Inventory of McNary NWR [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on McNary National Wildlife Refuge. Trails in this inventory are eligible...

  4. The Trail Inventory of Steigerwald Lake NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Steigerwald Lake National Wildlife Refuge. Trails in this inventory are...

  5. The Trail Inventory of Salinas River NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Salinas River National Wildlife Refuge. Trails in this inventory are...

  6. The Trail Inventory of Chassahowitzka National Wildlife Refuge [Cycle 1

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Chassahowitzka National Wildlife Refuge. Trails in this inventory are...

  7. The Trail Inventory of Welaka NFH [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Welaka National Fish Hatchery. Trails in this inventory are eligible for...

  8. The Trail Inventory of Ruby Lake NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Ruby Lake National Wildlife Refuge. Trails in this inventory are...

  9. The Trail Inventory of Ruby Lake NWR [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Ruby Lake National Wildlife Refuge. Trails in this inventory are...

  10. The Trail Inventory of Chautauqua National Wildlife Refuge [Cycle 1

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Chautauqua National Wildlife Refuge. Trails in this inventory are...

  11. The Trail Inventory of Alaska Maritime NWR [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Alaska Maritime National Wildlife Refuge. Trails in this inventory are...

  12. The Trail Inventory of William L. Finley NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on William L. Finley National Wildlife Refuge. Trails in this inventory are...

  13. The Trail Inventory of Bill Williams River NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Bill Williams River National Wildlife Refuge. Trails in this inventory...

  14. The Trail Inventory of William L. Finley NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on William L. Finley National Wildlife Refuge. Trails in this inventory are...

  15. The Trail Inventory of St. Croix WMD [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on St. Croix Wetland Management District. Trails in this inventory are...

  16. The Trail Inventory of Tishomingo NFH [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Tishomingo National Fish Hatchery. Trails in this inventory are eligible...

  17. The Trail Inventory of Kealia Pond NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Kealia Pond National Wildlife Refuge. Trails in this inventory are...

  18. The Trail Inventory of Elizabeth A. Morton NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Elizabeth Alexandra Morton National Wildlife Refuge. Trails in this...

  19. The Trail Inventory of Elizabeth A. Morton NWR [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Elizabeth Alexandra Morton National Wildlife Refuge. Trails in this...

  20. US Forest Service National Forest System Trails With Data Status

    Data.gov (United States)

    US Forest Service, Department of Agriculture — A map service on the world wide web that depicts National Forest Service trails that have been approved for publication. It also depicts the availability of trails...

  1. The Trail Inventory of Huron WMD [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Huron Wetland Management District. Trails in this inventory are eligible...

  2. The Trail Inventory of Attwater Prairie Chicken NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Attwater Prairie Chicken National Wildlife Refuge. Trails in this...

  3. The Trail Inventory of Wichita Mountains NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Wichita Mountains Wildlife Refuge. Trails in this inventory are eligible...

  4. The Trail Inventory of Rocky Mountain Arsenal NWR [Cycle 1

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Rocky Mountain Arsenal National Wildlife Refuge. Trails in this inventory...

  5. The Trail Inventory of Medicine Lake NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Medicine Lake National Wildlife Refuge. Trails in this inventory are...

  6. The Trail Inventory of Medicine Lake NWR [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Medicine Lake National Wildlife Refuge. Trails in this inventory are...

  7. The Trail Inventory of Middle Mississippi River NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Middle Mississippi River National Wildlife Refuge. Trails in this...

  8. The Trail Inventory of Kenai NWR [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Kenai National Wildlife Refuge. Trails in this inventory are eligible for...

  9. The Trail Inventory of Berkshire National Fish Hatchery [Cycle 1

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Berkshire Trout Hatchery. Trails in this inventory are eligible for...

  10. The Trail Inventory of Berkshire NFH [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Berkshire Trout Hatchery. Trails in this inventory are eligible for...

  11. The Trail Inventory of Berkshire NFH [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all non-motorized trails on Berkshire Trout Hatchery. Trails in this inventory are eligible for...

  12. The Trail Inventory of Kenai National Wildlife Refuge [Cycle 1

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Kenai National Wildlife Refuge. Trails in this inventory are eligible for...

  13. The Trail Inventory of Ankeny NWR [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Ankeny National Wildlife Refuge. Trails in this inventory are eligible...

  14. The Trail Inventory of Iron River NFH [Cycle 2

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Iron River National Fish Hatchery. Trails in this inventory are eligible...

  15. The Trail Inventory of Imperial NWR [Cycle 3

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Imperial National Wildlife Refuge. Trails in this inventory are eligible...

  16. The Trail Inventory of Muscatatuck National Wildlife Refuge [Cycle 1

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of this report is to create a baseline inventory of all nonmotorized trails on Muscatatuck National Wildlife Refuge. Trails in this inventory are...

  17. The Best Trail Algorithm for Assisted Navigation of Web Sites

    OpenAIRE

    Wheeldon, Richard; Levene, Mark

    2003-01-01

    We present an algorithm called the Best Trail Algorithm, which helps solve the hypertext navigation problem by automating the construction of memex-like trails through the corpus. The algorithm performs a probabilistic best-first expansion of a set of navigation trees to find relevant and compact trails. We describe the implementation of the algorithm, scoring methods for trails, filtering algorithms and a new metric called \\emph{potential gain} which measures the potential of a page for futu...

  18. Molecular mechanisms of TRAIL-induced apoptosis of cancer cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Tumor Necrosis Factor-related Apoptosis-inducing Ligand (TRAIL) is a recently identified member of the tumor necrosis factor (TNF) family[1]. Numerous studies indicate that TRAIL can induce apoptosis of cancer cells but not of normal cells, pointing to the possibility of de-veloping TRAIL into a cancer drug[2-4]. This review will summary the molecular mechanisms of TRAIL-induced apoptosis and discuss the questions to be resolved in this field.

  19. Stress analysis in the last stage blade of a geothermal turbine under different excitation conditions; Analisis de esfuerzos en el alabe de la ultima etapa de turbina geotermica bajo diferentes condiciones de excitacion

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez Alcazar, Rony Ediberto

    2009-11-15

    The blades of the steam turbines operate below severe conditions of pressure, temperature and steam flow, and at high rotary speeds too. These excitements generate states of stress, which depending on its magnitude and time of application; they can threaten the structural reliability of these mechanical components. In this work a stress analysis is realized in a blade L-0 of a geothermal turbine of low pressure, by means of the finite element method, by the aim to determine the states of static stress caused by the combined action of the centrifugal force and pressure of system flow, and dynamic stresses caused by the harmonic fluctuation in the steam flow. The analysis is realized under two superficial conditions in the blade: without presence of superficial damage and with presence of erosion in the bottom part of the trailing edge. The combined action of these conditions of stress is evaluated by means of an analysis of fatigue. This allows knowing the influence of the stress calculated, on the useful life of the blade. [Spanish] Los alabes de turbinas de vapor operan bajo condiciones severas de presion, temperatura y flujo de vapor, asi como a altas velocidades rotativas. Estas excitaciones generan estados de esfuerzos, que dependiendo de su magnitud y tiempo de aplicacion, pueden amenazar la confiabilidad estructural de estos componentes mecanicos. En este trabajo se realiza un analisis de esfuerzos en un alabe L-0 de una turbina geotermica de baja presion, mediante el metodo de elemento finito, con el objetivo de determinar los estados de esfuerzos estaticos causados por la accion combinada de la carga por fuerza centrifuga y presion de flujo de vapor, y esfuerzos dinamicos causados por la fluctuacion armonica en el flujo de vapor. El analisis se realiza bajo dos condiciones superficiales en el alabe: sin presencia de dano superficial y con presencia de erosion en la parte inferior del borde de salida. La accion combinada de estos estados de esfuerzos se

  20. 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.

  1. 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.

  2. 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.

  3. Development of Advanced High Lift Leading Edge Technology for Laminar Flow Wings

    Science.gov (United States)

    Bright, Michelle M.; Korntheuer, Andrea; Komadina, Steve; Lin, John C.

    2013-01-01

    This paper describes the Advanced High Lift Leading Edge (AHLLE) task performed by Northrop Grumman Systems Corporation, Aerospace Systems (NGAS) for the NASA Subsonic Fixed Wing project in an effort to develop enabling high-lift technology for laminar flow wings. Based on a known laminar cruise airfoil that incorporated an NGAS-developed integrated slot design, this effort involved using Computational Fluid Dynamics (CFD) analysis and quality function deployment (QFD) analysis on several leading edge concepts, and subsequently down-selected to two blown leading-edge concepts for testing. A 7-foot-span AHLLE airfoil model was designed and fabricated at NGAS and then tested at the NGAS 7 x 10 Low Speed Wind Tunnel in Hawthorne, CA. The model configurations tested included: baseline, deflected trailing edge, blown deflected trailing edge, blown leading edge, morphed leading edge, and blown/morphed leading edge. A successful demonstration of high lift leading edge technology was achieved, and the target goals for improved lift were exceeded by 30% with a maximum section lift coefficient (Cl) of 5.2. Maximum incremental section lift coefficients ( Cl) of 3.5 and 3.1 were achieved for a blown drooped (morphed) leading edge concept and a non-drooped leading edge blowing concept, respectively. The most effective AHLLE design yielded an estimated 94% lift improvement over the conventional high lift Krueger flap configurations while providing laminar flow capability on the cruise configuration.

  4. 30 CFR 57.4057 - Underground trailing cables.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground trailing cables. 57.4057 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Fire Prevention and Control § 57.4057 Underground trailing cables. Underground trailing cables shall be accepted...

  5. Recombinant soluble TRAIL induces apoptosis of cancer cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    TRAIL is a tumor necrosis factor family member that selectively induces apoptosis of cancer cells but not of normal cells. To develop TRAIL into a potential cancer drug, three different sizes of soluble TRAIL fragments, including sTRAIL(74-281), sTRAIL(95-281) and sTRAIL(101-281), were expressed in E. coli and purified to homogeneity. Apoptosis assays indicated that sTRAIL(95-281) and sTRAIL(101-281), but not sTRAIL(74-281), can potently induce apoptosis of various cancer cell lines in 6 h, suggesting that the N-terminal fragment of aa101 has inhibitory effect on TRAIL-induced apoptosis. Moreover, we found that some cancer cells were resistant to TRAIL and the resistant cells could be converted into sensitive cells by treatment with the protein synthesis inhibitor cycloheximide, suggesting that one or more short-lived proteins are responsible for cells' resistance to TRAIL.

  6. Trails, Other, scouts trail districts, Published in 2006, 1:24000 (1in=2000ft) scale, Tooele County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Trails, Other dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Other information as of 2006. It is described as 'scouts trail...

  7. Trails, Other, scouts trail districts poly, Published in 2006, 1:24000 (1in=2000ft) scale, Tooele County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Trails, Other dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Other information as of 2006. It is described as 'scouts trail...

  8. Trails, Other, trails, Published in 2008, 1:24000 (1in=2000ft) scale, Box Elder County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Trails, Other dataset, published at 1:24000 (1in=2000ft) scale, was produced all or in part from Other information as of 2008. It is described as 'trails'. The...

  9. TRIPPy: Trailed Image Photometry in Python

    CERN Document Server

    Fraser, Wesley C; Schwamb, Megan E; Marsset, Michael E; Pike, Rosemary E; Kavelaars, JJ; Bannister, Michele T; Benecchi, Susan; Delsanti, Audrey

    2016-01-01

    Photometry of moving sources typically suffers from reduced signal-to-noise (SNR) or flux measurements biased to incorrect low values through the use of circular apertures. To address this issue we present the software package, TRIPPy: TRailed Image Photometry in Python. TRIPPy introduces the pill aperture, which is the natural extension of the circular aperture appropriate for linearly trailed sources. The pill shape is a rectangle with two semicircular end-caps, and is described by three parameters, the trail length and angle, and the radius. The TRIPPy software package also includes a new technique to generate accurate model point-spread functions (PSF) and trailed point-spread functions (TSF) from stationary background sources in sidereally tracked images. The TSF is merely the convolution of the model PSF, which consists of a moffat profile, and super sampled lookup table. From the TSF, accurate pill aperture corrections can be estimated as a function of pill radius with a accuracy of 10 millimags for hi...

  10. Tracing the X-Ray Trail

    Science.gov (United States)

    What you need to know about… Tracing the X-ray Trail If you’ve just completed an x-ray, computed tomography (CT), magnetic resonance (MR) Start here! or other diagnostic imaging procedure, you probably want to know when you will ... los rayos X Si acaba de hacerse una radiografía, tomografía ¡Empezar ...

  11. Certification trails and software design for testability

    Science.gov (United States)

    Sullivan, Gregory F.; Wilson, Dwight S.; Masson, Gerald M.

    1993-01-01

    Design techniques which may be applied to make program testing easier were investigated. Methods for modifying a program to generate additional data which we refer to as a certification trail are presented. This additional data is designed to allow the program output to be checked more quickly and effectively. Certification trails were described primarily from a theoretical perspective. A comprehensive attempt to assess experimentally the performance and overall value of the certification trail method is reported. The method was applied to nine fundamental, well-known algorithms for the following problems: convex hull, sorting, huffman tree, shortest path, closest pair, line segment intersection, longest increasing subsequence, skyline, and voronoi diagram. Run-time performance data for each of these problems is given, and selected problems are described in more detail. Our results indicate that there are many cases in which certification trails allow for significantly faster overall program execution time than a 2-version programming approach, and also give further evidence of the breadth of applicability of this method.

  12. Metastasis suppressor function of TRAIL-R in mice- implications for TRAIL-based therapy in humans?

    OpenAIRE

    Grosse-Wilde, Anne; Kemp, Christopher J

    2008-01-01

    TRAIL is a promising candidate for cancer therapy, as it can induce apoptosis specifically in tumor cells but not in normal cells. While earlier mouse tumor studies revealed a strong tissue dependency of TRAIL and its death receptor in suppressing primary tumorigenesis or experimental metastases, we recently found that TRAIL-R inhibits lymph node metastases without affecting primary tumor formation in a mouse model of multistage skin tumorigenesis. This finding uncouples the role of TRAIL in ...

  13. 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.

  14. 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

  15. 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.

  16. Histopathologic Comparison of Radiofrequency and Scalpel Blade on Mice Skin Incisional Wound Healing Model

    Directory of Open Access Journals (Sweden)

    Banafshe Gholamhoseini*, Soroush Mohitmafi1, Payam Razeghi Tehrani2 and Sattar Noorialeagha3

    2012-06-01

    Full Text Available Using a safe and accurate alternative to scalpel blades for various surgical operations has been more considering today. There are many studies about the healing process of various tissues after using different methods like radiofrequency, electro surgery and scalpel blade for the surgical incisions, but choosing the right instrument is very important in cosmetic surgeries.This study was undertaken to get more histopathologic details about the healing process after using either Radiofrequency (RF or Scalpel blade as a skin incision method. So, an experimental study was designed in that 12 mice were randomly divided in three groups with the same situation and two different incisions were cut in each mouse on ventral skin by scalpel blade and radio surgical equipment. The skin specimens from scalpel blade incision as group one sample and radiosurgical incision as group two sample were harvested on the same operation day and a weekly manner to day 21. All samples were stained with Hematoxillin - Eosin and observed under light microscopy. Results showed less tissue contraction at the cutting edge and better collagen alignments in RF incision in comparison to scalpel blade incisions in which having fibrosis and more tissue contraction. These histopathologic findings might be the reason for more elasticity and less scar tissue remaining after skin Radiofrequency surgery.

  17. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-08-15

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

  19. Numerical Analysis of Stress on Pump Blade by One-Way Coupled Fluid-Structure Simulation

    Science.gov (United States)

    Kobayashi, Katsutoshi; Ono, Shigeyoshi; Harada, Ichiro; Chiba, Yoshimasa

    A mixed-flow pump with an unshrouded impeller was computed by a one-way coupled fluid-structure simulation to evaluate a prediction accuracy of stress and analyze a flow pattern which caused the largest stress. The stress occurring around a blade root was predicted by a numerical simulation and compared with an experimental one. Five flow rates, Q/Qbep=0,40,70,100 and 120% were simulated and the predicted stresses at all flow rates agreed with the experimental ones within -11˜+6% accuracy. The largest stress occurred around a blade root on a pressure side of blade surface at all flow rates. The stress became largest at 70% flow rate. A flow pattern around the blade was analyzed to investigate how the largest stress occurred at 70% flow rate. It was found in this study that a flow separation occurred around a leading edge on a suction side of blade surface at 70% flow rate and the largest load was acting on an outside region of blade.

  20. Robust Design Optimization Method for Centrifugal Impellers under Surface Roughness Uncertainties Due to Blade Fouling

    Institute of Scientific and Technical Information of China (English)

    JU Yaping; ZHANG Chuhua

    2016-01-01

    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  1. Robust design optimization method for centrifugal impellers under surface roughness uncertainties due to blade fouling

    Science.gov (United States)

    Ju, Yaping; Zhang, Chuhua

    2016-03-01

    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  2. Vibration Analysis of Large Composite Blade Wind Turbine

    Directory of Open Access Journals (Sweden)

    Yuqiao Zheng

    2013-09-01

    Full Text Available This paper presents a recently developed the finite model method for analysis of horizontal axis wind turbine blades.Free vibration equation is proposed based on theory of  the classical lamination and  Lagrange method.. A 40 m rotor blade was chosen as a example study to validate the static and dynamic behaviour predicted by shell model built in ANSYS,Given uncertainty of material properties involved,An accurate agreement was found for static deformation curves, as well as a good prediction of the lowest frequency modes in terms of resonance frequencies, the highest (eighth frequency modes show only a fair agreement as expected for an FE model,Flap-wise, edge-wise and  torsional  natural  frequencies of  a  variable  length  blade  have been investigated,The results show that the approach used in this study is very efficient and produces improved designs as compared with a reference or baseline design.

  3. Forest edge development

    OpenAIRE

    Wiström, Björn

    2015-01-01

    This thesis investigates design guidelines and management systems for the development of stationary forest edges with a graded profile in infrastructure and urban environments. The spatial restriction for the edge to move forward caused by human land use counteracts the natural dynamics and development patterns of graded forest edges. However graded forest edges with successively increasing height from the periphery to the interior of the forest edge are often seen as ideal as they supports ...

  4. Measurements on the thunder TH-6R actuator[For wind turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Bohn, T.; Gaunaa, M.; Bak, C.; Hansen, Per; Clemmensen, K.

    2005-11-01

    This report is a collection of the measurements carried out on the TH-6R actuator from Face International Co. The work is a part of the ADAPWING project, which aims at developing a method to alleviate some of the fluctuating response of a wind turbine by using adaptive trailing edge geometry. The ultimate goal of the project is to make a prototype and test this in a wind tunnel. First step is to clarify whether the actuator can be used for this purpose. The report will include: static and dynamic test of the actuator, test in different ranges of its operational range and comparison of two actuators. One of the important fact that is discovered is that the actuator response has a clear hysteresis loop. This fact must be taken into account when using the actuator as trailing edge geometry on the wind turbine wing. (au)

  5. Possible novel therapy for malignant gliomas with secretable trimeric TRAIL.

    Directory of Open Access Journals (Sweden)

    Moonsup Jeong

    Full Text Available Malignant gliomas are the most common primary brain tumors. Despite intensive clinical investigation and many novel therapeutic approaches, average survival for the patients with malignant gliomas is only about 1 year. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL has shown potent and cancer-selective killing activity and drawn considerable attention as a promising therapy for cancers, but concerns over delivery and toxicity have limited progress. We have developed a secretable trimeric TRAIL (stTRAIL and here evaluated the therapeutic potential of this stTRAIL-based gene therapy in brain tumors. An adenovirus (Ad-stTRAIL delivering stTRAIL was injected into intra-cranial human glioma tumors established in nude mice and tumor growth monitored using the magnetic resonance imaging (MRI. Ad-stTRAIL gene therapy showed potent tumor suppressor activity with no toxic side effects at therapeutically effective doses. When compared with 1, 3-bis(2-chloroethyl-1-nitrosourea (BCNU, a conventional therapy for malignant gliomas, Ad-stTRAIL suppressed tumor growth more potently. The combination of Ad-stTRAIL and BCNU significantly increased survival compared to the control mice or mice receiving Ad-stTRAIL alone. Our data indicate that Ad-stTRAIL, either alone or combined with BCNU, has promise as a novel therapy for malignant gliomas.

  6. Metallographic investigations of metal plate edges after cutting

    Directory of Open Access Journals (Sweden)

    D. Gąsiorek

    2013-09-01

    Full Text Available Purpose: Cutting sheets of various materials is a commonly used product finishing process in industrial conditions. If high quality of cut edges is required, defects caused by cutting on a guillotine make this process of finishing practically unsuitable. The Authors evaluated quality of plates after cutting in laboratory, on industrial guillotine and a rotary slitter, in order to specify a cutting method least disturbing to the product’s edge. Design/methodology/approach: Samples of multi-layered aluminium lithographic plates, divided by cardboard and paper sheets were cut in industrial conditions on a guillotine and a rotary slitter. A specially designed laboratory test stand was built, allowing measurements of forces and applying a vertical, controlled movement of the cutting blade. Surfaces of edges of the samples were examined with the use of a Scanning Electronic Microscope; results of these scans were compared and evaluated. Findings: Comparison of surfaces after cutting allowed drawing conclusions regarding methods causing minimum disturbances to the cut edges. The best quality of the cut edges was obtained on a laboratory guillotine test stand, applying a unique, vertical movement of the cutting blade. Research limitations/implications: Results of laboratory experiments should be continued and verified on larger scale in industrial conditions. Practical implications: If vertical cutters could deliver the same edge quality as rotary slitters, a substantial reduction of production costs can be expected as in many cases guillotines are far more efficient than rotary slitters. Originality/value: Vertical, controlled movement of the blade during cutting metal sheets offers substantial advantages to the finishing process compared to standard guillotine cutting. In all cases, when high quality of the edge surface is required, proposed vertical cutting combines high efficiency with simplicity of operations and assures high quality of the

  7. Molecular Targets of TRAIL-Sensitizing Agents in Colorectal Cancer

    Directory of Open Access Journals (Sweden)

    Giovanni Monteleone

    2012-06-01

    Full Text Available Tumor necrosis factor (TNF-related apoptosis inducing ligand (TRAIL, a member of the TNF superfamily, interacts with its functional death receptors (DRs and induces apoptosis in a wide range of cancer cell types. Therefore, TRAIL has been considered as an attractive agent for cancer therapy. However, many cancers are resistant to TRAIL-based therapies mainly due to the reduced expression of DRs and/or up-regulation of TRAIL pathway-related anti-apoptotic proteins. Compounds that revert such defects restore the sensitivity of cancer cells to TRAIL, suggesting that combined therapies could help manage neoplastic patients. In this article, we will focus on the TRAIL-sensitizing effects of natural products and synthetic compounds in colorectal cancer (CRC cells and discuss the molecular mechanisms by which such agents enhance the response of CRC cells to TRAIL.

  8. Judder-Induced Edge Flicker at Zero Spatial Contrast

    Science.gov (United States)

    Larimer, James; Feng, Christine; Gille, Jennifer; Cheung, Victor

    2004-01-01

    Judder is a motion artifact that degrades the quality of video imagery. Smooth motion appears jerky and can appear to flicker along the leading and trailing edge of the moving object. In a previous paper, we demonstrated that the strength of the edge flicker signal depended upon the brightness of the scene and the contrast of the moving object relative to the background. Reducing the contrast between foreground and background reduced the flicker signal. In this report, we show that the contrast signal required for judder-induced edge flicker is due to temporal contrast and not simply to spatial contrast. Bars made of random dots of the same dot density as the background exhibit edge flicker when moved at sufficient rate.

  9. The edges of graphene

    Science.gov (United States)

    Zhang, Xiuyun; Xin, John; Ding, Feng

    2013-03-01

    The edge of two dimensional (2D) graphene, as the surface of a three dimensional (3D) crystal, plays a crucial role in the determination of its physical, electronic and chemical properties and thus has been extensively studied recently. In this review, we summarize the recent advances in the study of graphene edges, including edge formation energy, edge reconstruction, method of graphene edge synthesis and the recent progress on metal-passivated graphene edges and the role of edges in graphene CVD growth. We expect this review to provide a guideline for readers to gain a clear picture of graphene edges from several aspects, especially the catalyst-passivated graphene edges and their role in graphene CVD growth.

  10. The edges of graphene.

    Science.gov (United States)

    Zhang, Xiuyun; Xin, John; Ding, Feng

    2013-04-01

    The edge of two dimensional (2D) graphene, as the surface of a three dimensional (3D) crystal, plays a crucial role in the determination of its physical, electronic and chemical properties and thus has been extensively studied recently. In this review, we summarize the recent advances in the study of graphene edges, including edge formation energy, edge reconstruction, method of graphene edge synthesis and the recent progress on metal-passivated graphene edges and the role of edges in graphene CVD growth. We expect this review to provide a guideline for readers to gain a clear picture of graphene edges from several aspects, especially the catalyst-passivated graphene edges and their role in graphene CVD growth. PMID:23420074

  11. Influenza leaves a TRAIL to pulmonary edema.

    Science.gov (United States)

    Brauer, Rena; Chen, Peter

    2016-04-01

    Influenza infection can cause acute respiratory distress syndrome (ARDS), leading to poor disease outcome with high mortality. One of the driving features in the pathogenesis of ARDS is the accumulation of fluid in the alveoli, which causes severe pulmonary edema and impaired oxygen uptake. In this issue of the JCI, Peteranderl and colleagues define a paracrine communication between macrophages and type II alveolar epithelial cells during influenza infection where IFNα induces macrophage secretion of TRAIL that causes endocytosis of Na,K-ATPase by the alveolar epithelium. This reduction of Na,K-ATPase expression decreases alveolar fluid clearance, which in turn leads to pulmonary edema. Inhibition of the TRAIL signaling pathway has been shown to improve lung injury after influenza infection, and future studies will be needed to determine if blocking this pathway is a viable option in the treatment of ARDS. PMID:26999598

  12. Experimental Blade Research - phase 2

    DEFF Research Database (Denmark)

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

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

  13. Multiple piece turbine rotor blade

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Keith D.; Plank, William L.

    2016-07-19

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

  14. TRAIL-coated lipid-nanoparticles overcome resistance to soluble recombinant TRAIL in non-small cell lung cancer cells

    Science.gov (United States)

    De Miguel, Diego; Gallego-Lleyda, Ana; María Ayuso, José; Erviti-Ardanaz, Sandra; Pazo-Cid, Roberto; del Agua, Celia; José Fernández, Luis; Ochoa, Ignacio; Anel, Alberto; Martinez-Lostao, Luis

    2016-05-01

    Purpose. Non-small cell lung cancer (NSCLC) is one the types of cancer with higher prevalence and mortality. Apo2-Ligand/TRAIL is a TNF family member able to induce apoptosis in tumor cells but not in normal cells. It has been tested in clinical trials against different types of human cancer including NSCLC. However, results of clinical trials have shown a limited efficacy of TRAIL-based therapies. Recently we have demonstrated that artificial lipid nanoparticles coated with bioactive Apo2L/TRAIL (LUV-TRAIL) greatly improved TRAIL cytotoxic ability being capable of killing chemoresistant hematological cancer cells. In the present work we have extended the study to NSCLC. Methods/patients. LUV-TRAIL-induced cytotoxicity was assessed on different NSCLC cell lines with different sensitivity to soluble TRAIL and on primary human tumor cells from three patients suffering from NSCLC cancer. We also tested LUV-TRAIL-cytotoxic ability in combination with several anti-tumor agents. Results. LUV-TRAIL exhibited a greater cytotoxic effect compared to soluble TRAIL both in A549 cells and primary human NSCLC cells. LUV-TRAIL-induced cell death was dependent on caspase-8 and caspase-3 activation. Moreover, combination of LUV-TRAIL with other anti-tumor agents such as flavopiridol, and SNS-032 clearly enhanced LUV-TRAIL-induced cytotoxicity against NSCLC cancer cells. Conclusion. The novel formulation of TRAIL based on displaying it on the surface of lipid nanoparticles greatly increases its anti-tumor activity and has clinical potential in cancer treatment.

  15. TRAIL treatment provokes mutations in surviving cells

    OpenAIRE

    Lovric, M M; Hawkins, C J

    2010-01-01

    Chemotherapy and radiotherapy commonly damage DNA and trigger p53-dependent apoptosis through intrinsic apoptotic pathways. Two unfortunate consequences of this mechanism are resistance due to blockade of p53 or intrinsic apoptosis pathways, and mutagenesis of non-malignant surviving cells which can impair cellular function or provoke second malignancies. Death ligand-based drugs, such as tumor necrosis factor-related apoptosis inducing ligand (TRAIL), stimulate extrinsic apoptotic signaling,...

  16. Heavy water at Trail, British Columbia

    International Nuclear Information System (INIS)

    Today Canada stands on the threshold of a nuclear renaissance, based on the CANDU reactor family, which depends on heavy water as a moderator and for cooling. Canada has a long history with heavy water, with commercial interests beginning in 1934, a mere two years after its discovery. At one time Canada was the world's largest producer of heavy water. The Second World War stimulated interest in this rather rare substance, such that the worlds largest supply (185 kg) ended up in Canada in 1942 to support nuclear research work at the Montreal Laboratories of the National Research Council. A year later commercial production began at Trail, British Columbia, to support work that later became known as the P-9 project, associated with the Manhattan Project. The Trail plant produced heavy water from 1943 until 1956, when it was shut down. During the war years the project was so secret that Lesslie Thomson, Special Liaison Officer reporting on nuclear matters to C.D. Howe, Minister of Munitions and Supply, was discouraged from visiting Trail operations. Thomson never did visit the Trail facility during the war. In 2005 the remaining large, tall concrete exchange tower was demolished at a cost of about $2.4 million, about the same as it cost to construct the facility about 60 years ago. Thus no physical evidence remains of this historic facility and another important artifact from Canada's nuclear history has disappeared forever. It is planned to place a plaque at the site at some point in the future. (author)

  17. Model of turbine blades bundles

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    Prague : Institute of Thermomechanics, Academy of Sciences of the Czech Republic, v. v. i., 2013 - (Zolotarev, I.), s. 467-477 ISBN 978-80-87012-47-5. ISSN 1805-8256. [Engineering Mechanics 2013 /19./. Svratka (CZ), 13.05.2013-16.05.2013] R&D Projects: GA ČR GA101/09/1166 Institutional support: RVO:61388998 Keywords : free and forced vibrations * eigenmodes * mathematical model * bundle of blades Subject RIV: BI - Acoustics

  18. Model of turbine blades bundles

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    Praha : Insitute of Thermomechanics ASCR, v. v. i., 2013 - (Zolotarev, I.). s. 125-126 ISBN 978-80-87012-46-8. ISSN 1805-8248. [Engineering Mechanics 2013 /19./. 13.05.2013-16.05.2013, Svratka] R&D Projects: GA ČR GA101/09/1166 Institutional support: RVO:61388998 Keywords : free and forced vibrations * eigenmodes * bundle of blades Subject RIV: BI - Acoustics

  19. Blockade of Death Ligand TRAIL Inhibits Renal Ischemia Reperfusion Injury

    International Nuclear Information System (INIS)

    Renal ischemia-reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI). Many investigators have reported that cell death via apoptosis significantly contributed to the pathophysiology of renal IRI. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor superfamily, and induces apoptosis and inflammation. However, the role of TRAIL in renal IRI is unclear. Here, we investigated whether TRAIL contributes to renal IRI and whether TRAIL blockade could attenuate renal IRI. AKI was induced by unilateral clamping of the renal pedicle for 60 min in male FVB/N mice. We found that the expression of TRAIL and its receptors were highly upregulated in renal tubular cells in renal IRI. Neutralizing anti-TRAIL antibody or its control IgG was given 24 hr before ischemia and a half-dose booster injection was administered into the peritoneal cavity immediately after reperfusion. We found that TRAIL blockade inhibited tubular apoptosis and reduced the accumulation of neutrophils and macrophages. Furthermore, TRAIL blockade attenuated renal fibrosis and atrophy after IRI. In conclusion, our study suggests that TRAIL is a critical pathogenic factor in renal IRI, and that TRAIL could be a new therapeutic target for the prevention of renal IRI

  20. Modulation of leading edge vorticity and aerodynamic forces in flexible flapping wings

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Liang; Deng Xinyan [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907 (United States); Sane, Sanjay P, E-mail: xdeng@purdue.edu, E-mail: sane@ncbs.res.in [National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bellary Road, Bangalore 560 065 (India)

    2011-09-15

    In diverse biological flight systems, the leading edge vortex has been implicated as a flow feature of key importance in the generation of flight forces. Unlike fixed wings, flapping wings can translate at higher angles of attack without stalling because their leading edge vorticity is more stable than the corresponding fixed wing case. Hence, the leading edge vorticity has often been suggested as the primary determinant of the high forces generated by flapping wings. To test this hypothesis, it is necessary to modulate the size and strength of the leading edge vorticity independently of the gross kinematics while simultaneously monitoring the forces generated by the wing. In a recent study, we observed that forces generated by wings with flexible trailing margins showed a direct dependence on the flexural stiffness of the wing. Based on that study, we hypothesized that trailing edge flexion directly influences leading edge vorticity, and thereby the magnitude of aerodynamic forces on the flexible flapping wings. To test this hypothesis, we visualized the flows on wings of varying flexural stiffness using a custom 2D digital particle image velocimetry system, while simultaneously monitoring the magnitude of the aerodynamic forces. Our data show that as flexion decreases, the magnitude of the leading edge vorticity increases and enhances aerodynamic forces, thus confirming that the leading edge vortex is indeed a key feature for aerodynamic force generation in flapping flight. The data shown here thus support the hypothesis that camber influences instantaneous aerodynamic forces through modulation of the leading edge vorticity.