WorldWideScience

Sample records for airfoil section equipped

  1. 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...

  2. 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...

  3. 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)

  4. New airfoil sections for straight bladed turbine

    International Nuclear Information System (INIS)

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

  5. Turbine airfoil having outboard and inboard sections

    Science.gov (United States)

    Mazzola, Stefan; Marra, John J

    2015-03-17

    A turbine airfoil usable in a turbine engine and formed from at least an outboard section and an inboard section such that an inner end of the outboard section is attached to an outer end of the inboard section. The outboard section may be configured to provide a tip having adequate thickness and may extend radially inward from the tip with a generally constant cross-sectional area. The inboard section may be configured with a tapered cross-sectional area to support the outboard section.

  6. Analysis of viscous transonic flow over airfoil sections

    Science.gov (United States)

    Huff, Dennis L.; Wu, Jiunn-Chi; Sankar, L. N.

    1987-01-01

    A full Navier-Stokes solver has been used to model transonic flow over three airfoil sections. The method uses a two-dimensional, implicit, conservative finite difference scheme for solving the compressible Navier-Stokes equations. Results are presented as prescribed for the Viscous Transonic Airfoil Workshop to be held at the AIAA 25th Aerospace Sciences Meeting. The NACA 0012, RAE 2822 and Jones airfoils have been investigated for both attached and separated transonic flows. Predictions for pressure distributions, loads, skin friction coefficients, boundary layer displacement thickness and velocity profiles are included and compared with experimental data when possible. Overall, the results are in good agreement with experimental data.

  7. Stability investigation of an airfoil section with active flap control

    OpenAIRE

    Bergami, Leonardo; Gaunaa, Mac

    2010-01-01

    This work presents a method to determine flutter and divergence instability limits for a two-dimensional (2-D) airfoil section fitted with an actively controlled trailing edge flap. This flap consists of a deformable trailing edge, which deformation is governed by control algorithms based on measurements of either heave displacement, local angle of attack or aerodynamic pressure difference measured over the airfoil. The purpose of the controlled deformable flap is to reduce fluctuations in th...

  8. Airfoil

    Science.gov (United States)

    Ristau, Neil; Siden, Gunnar Leif

    2015-07-21

    An airfoil includes a leading edge, a trailing edge downstream from the leading edge, a pressure surface between the leading and trailing edges, and a suction surface between the leading and trailing edges and opposite the pressure surface. A first convex section on the suction surface decreases in curvature downstream from the leading edge, and a throat on the suction surface is downstream from the first convex section. A second convex section is on the suction surface downstream from the throat, and a first convex segment of the second convex section increases in curvature.

  9. Stability investigation of an airfoil section with active flap control

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Gaunaa, Mac

    2010-01-01

    fatigue load alleviation. The structural model of the 2-D airfoil section contains three degrees of freedom: heave translation, pitch rotation and flap deflection. A potential flow model provides the aerodynamic forces and their distribution. The unsteady aerodynamics are described using an indicial...

  10. Profile catalogue for airfoil sections based on 3D computations

    DEFF Research Database (Denmark)

    Bertagnolio, F.; Sørensen, Niels N.; Johansen, Jeppe

    2006-01-01

    This report is a continuation of the Wind Turbine Airfoil Catalogue [1] which objective was, firstly to provide a database of aerodynamic characteristics for a wide range of airfoil profiles aimed at wind turbine applications, and secondly to test thetwo-dimensional Navier-Stokes solver EllipSys2D...... and the actual fluid flow, and thereby the incorrect prediction of airfoil characteristics. In addition, other features of the flow solver, such astransition and turbulence modelling, and their influence onto the numerical results are investigated. Conclusions are drawn regarding the evaluation of...... airfoil aerodynamic characteristics, as well as the use of the Navier-Stokes solver for fluid flowcalculations in general....

  11. Profile catalogue for airfoil sections based on 3D

    Energy Technology Data Exchange (ETDEWEB)

    Bertagnolio, F.; Soerensen, Niels N.; Johansen, Jeppe

    2006-12-15

    This report is a continuation of the Wind Turbine Airfoil Catalogue which objective was, firstly to provide a database of aerodynamic characteristics for a wide range of airfoil profiles aimed at wind turbine applications, and secondly to test the two-dimensional Navier-Stokes solver EllipSys2D by comparing its results with experimental data. In the present work, the original two-dimensional results are compared with three-dimensional calculations as it was surmised that the two-dimensional assumption might be in some cases responsible for discrepancies between the numerical flow solution and the actual fluid flow, and thereby the incorrect prediction of airfoil characteristics. In addition, other features of the flow solver, such as transition and turbulence modelling, and their influence onto the numerical results are investigated. Conclusions are drawn regarding the evaluation of airfoil aerodynamic characteristics, as well as the use of the Navier-Stokes solver for fluid flow calculations in general. (au)

  12. Experimental Study of Tip Vortex Flow from a Periodically Pitched Airfoil Section

    Science.gov (United States)

    Zaman, Khairul; Fagan, Amy; Mankbadi, Mina

    2016-01-01

    An experimental investigation of tip vortex flow from a NACA0012 airfoil, pitched periodically at various frequencies, is conducted in a low-speed wind tunnel. Initially, data for stationary airfoil held fixed at various angles-of-attack are gathered. Flow visualization pictures as well as detailed cross-sectional properties areobtained at various streamwise locations using hot-wire anemometry. Data include mean velocity, streamwise vorticity as well as various turbulent stresses. Preliminary data are also acquired for periodically pitched airfoil. These results are briefly presented in this extended abstract.

  13. Nonlinear angle control of a sectioned airfoil by using shape memory alloys

    Directory of Open Access Journals (Sweden)

    Abreu G.

    2014-01-01

    Full Text Available The present work illustrates an application of shape memory alloys and nonlinear controller applied to the active angular control of a sectioned airfoil. The main objective of the proposed control system is to modify the shape of the profile based on a reference angle. The change of the sectioned airfoil angle is resultant by the effect of shape memory of the alloy due to heating of the wire caused by an electric current that changes its temperature by Joule effect. Considering the presence of plant’s nonlinear effects, especially in the mathematical model of the alloy, this work proposes the application of an on-off control system.

  14. An Empirical Method Permitting Rapid Determination of the Area, Rate and Distribution of Water-Drop Impingement on an Airfoil of Arbitrary Section at Subsonic Speeds

    Science.gov (United States)

    Bergrun, N. R.

    1951-01-01

    An empirical method for the determination of the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The procedure represents an initial step toward the development of a method which is generally applicable in the design of thermal ice-prevention equipment for airplane wing and tail surfaces. Results given by the proposed empirical method are expected to be sufficiently accurate for the purpose of heated-wing design, and can be obtained from a few numerical computations once the velocity distribution over the airfoil has been determined. The empirical method presented for incompressible flow is based on results of extensive water-drop. trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range. The differential equations pertaining to the paths of the drops were solved by a differential analyzer. The method developed for incompressible flow is extended to the calculation of area and rate of impingement on straight wings in subsonic compressible flow to indicate the probable effects of compressibility for airfoils at low subsonic Mach numbers.

  15. Assessment of the performance of various airfoil sections on power generation from a wind turbine using the blade element momentum theory

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiaomin; Agarwal, Ramesh [Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, Jolley Hall, Campus Box 1185, One Brookings Drive, St. Louis, Missouri, 63130 (United States)

    2013-07-01

    It is well established that the power generated by a Horizontal-Axis Wind Turbine (HAWT) is a function of the number of blades, the tip speed ratio (blade tip speed/wind free stream velocity) and the lift to drag ratio (CL /CD) of the airfoil sections of the blade. The airfoil sections used in HAWT are generally thick airfoils such as the S, DU, FX, Flat-back and NACA 6-series of airfoils. These airfoils vary in (CL /CD) for a given blade and ratio and therefore the power generated by HAWT for different blade airfoil sections will vary. The goal of this paper is to evaluate the effect of different airfoil sections on HAWT performance using the Blade Element Momentum (BEM) theory. In this study, 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 blade and ratio 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 by the turbine can be significantly increased. Parametric studies are also conducted by varying the turbine diameter.

  16. Assessment of the performance of various airfoil sections on power generation from a wind turbine using the blade element momentum theory

    Directory of Open Access Journals (Sweden)

    Xiaomin Chen, Ramesh Agarwal

    2013-01-01

    Full Text Available It is well established that the power generated by a Horizontal-Axis Wind Turbine (HAWT is a function of the number of blades B, the tip speed ratio λ (blade tip speed/wind free stream velocity and the lift to drag ratio (CL /CD of the airfoil sections of the blade. The airfoil sections used in HAWT are generally thick airfoils such as the S, DU, FX, Flat-back and NACA 6-series of airfoils. These airfoils vary in (CL /CD for a given B and λ, and therefore the power generated by HAWT for different blade airfoil sections will vary. The goal of this paper is to evaluate the effect of different airfoil sections on HAWT performance using the Blade Element Momentum (BEM theory. In this study, 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 λ 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 by the turbine can be significantly increased. Parametric studies are also conducted by varying the turbine diameter.

  17. Rotational Augmentation on a 2.3 MW Rotor Blade with Thick Flatback Airfoil Cross-Sections: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Schreck, S.; Fingersh, L.; Siegel, K.; Singh, M.; Medina, P.

    2013-01-01

    Rotational augmentation was analyzed for a 2.3 MW wind turbine, which was equipped with thick flatback airfoils at inboard radial locations and extensively instrumented for acquisition of time varying surface pressures. Mean aerodynamic force and surface pressure data were extracted from an extensive field test database, subject to stringent criteria for wind inflow and turbine operating conditions. Analyses of these data showed pronounced amplification of aerodynamic forces and significant enhancements to surface pressures in response to rotational influences, relative to two-dimensional, stationary conditions. Rotational augmentation occurrence and intensity in the current effort was found to be consistent with that observed in previous research. Notably, elevated airfoil thickness and flatback design did not impede rotational augmentation.

  18. Nonlinear power flow feedback control for improved stability and performance of airfoil sections

    Science.gov (United States)

    Wilson, David G.; Robinett, III, Rush D.

    2013-09-03

    A computer-implemented method of determining the pitch stability of an airfoil system, comprising using a computer to numerically integrate a differential equation of motion that includes terms describing PID controller action. In one model, the differential equation characterizes the time-dependent response of the airfoil's pitch angle, .alpha.. The computer model calculates limit-cycles of the model, which represent the stability boundaries of the airfoil system. Once the stability boundary is known, feedback control can be implemented, by using, for example, a PID controller to control a feedback actuator. The method allows the PID controller gain constants, K.sub.I, K.sub.p, and K.sub.d, to be optimized. This permits operation closer to the stability boundaries, while preventing the physical apparatus from unintentionally crossing the stability boundaries. Operating closer to the stability boundaries permits greater power efficiencies to be extracted from the airfoil system.

  19. Effect of Flap Deflection on Section Characteristics of S813 Airfoil; Period of Performance: 1993--1994

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D. M.

    2005-01-01

    The effect of small deflections of a 30% chord, simple flap on the section characteristics of a tip airfoil, the S813, designed for 20- to 30-meter, stall-regulated, horizontal-axis wind turbines has been evaluated theoretically. The decrease in maximum lift coefficient due to leading-edge roughness increases in magnitude with increasing, positive flap deflection and with decreasing Reynolds number.

  20. Experimental Study of Tip Vortex Flow from a Periodically Pitched Airfoil Section

    Science.gov (United States)

    Zaman, KBMQ; Fagan, A. F.; Mankbadi, M. R.

    2016-01-01

    An experimental investigation of a tip vortex from a NACA0012 airfoil is conducted in a low-speed wind tunnel at a chord Reynolds number of 4x10(exp 4). Initially, data for a stationary airfoil held at various angles-of-attack (alpha) are gathered. Detailed surveys are done for two cases: alpha=10 deg with attached flow and alpha=25 deg with massive flow separation on the upper surface. Distributions of various properties are obtained using hot-wire anemometry. Data include mean velocity, streamwise vorticity and turbulent stresses at various streamwise locations. For all cases, the vortex core is seen to involve a mean velocity deficit. The deficit apparently traces to the airfoil wake, part of which gets wrapped by the tip vortex. At small alpha, the vortex is laminar within the measurement domain. The strength of the vortex increases with increasing alpha but undergoes a sudden drop around alpha (is) greater than 16 deg. The drop in peak vorticity level is accompanied by transition and a sharp rise in turbulence within the core. Data are also acquired with the airfoil pitched sinusoidally. All oscillation cases pertain to a mean alpha=15 deg while the amplitude and frequency are varied. An example of phase-averaged data for an amplitude of +/-10 deg and a reduced frequency of k=0.2 is discussed. All results are compared with available data from the literature shedding further light on the complex dynamics of the tip vortex.

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

    International Nuclear Information System (INIS)

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

  2. A parameter identification problem arising from a two-dimensional airfoil section model

    International Nuclear Information System (INIS)

    The development of state space models for aeroelastic systems, including unsteady aerodynamics, is particularly important for the design of highly maneuverable aircraft. In this work we present a state space formulation for a special class of singular neutral functional differential equations (SNFDE) with initial data in C(-1, 0). This work is motivated by the two-dimensional airfoil model presented by Burns, Cliff and Herdman in. In the same authors discuss the validity of the assumptions under which the model was formulated. They pay special attention to the derivation of the evolution equation for the circulation on the airfoil. This equation was coupled to the rigid-body dynamics of the airfoil in order to obtain a complete set of functional differential equations that describes the composite system. The resulting mathematical model for the aeroelastic system has a weakly singular component. In this work we consider a finite delay approximation to the model presented in. We work with a scalar model in which we consider the weak singularity appearing in the original problem. The main goal of this work is to develop numerical techniques for the identification of the parameters appearing in the kernel of the associated scalar integral equation. Clearly this is the first step in the study of parameter identification for the original model and the corresponding validation of this model for the aeroelastic system

  3. Evaluation of Wind-Tunnel Test Section for Airfoils and Bodies

    Czech Academy of Sciences Publication Activity Database

    Popelka, Lukáš; Matějka, M.; Šimurda, David; Součková, Natálie

    Prague : Institute of Thermomechanics AS CR, v. v. i., 2011 - (Příhoda, J.; Kozel, K.), s. 1-4 ISBN 978-80-87012-32-1. [Topical Problems of Fluid Mechanics 2011. Praha (CZ), 16.02.2011-17.02.2011] R&D Projects: GA ČR GA101/08/1112; GA MŠk(CZ) 1M06031 Institutional research plan: CEZ:AV0Z20760514 Keywords : wind tunnel * experimental aerodynamics * airfoil characterisitics Subject RIV: BK - Fluid Dynamics

  4. Airfoil structure

    Science.gov (United States)

    Frey, Gary A.; Twardochleb, Christopher Z.

    1998-01-01

    Past airfoil configurations have been used to improve aerodynamic performance and engine efficiencies. The present airfoil configuration further increases component life and reduces maintenance by reducing internal stress within the airfoil itself. The airfoil includes a chord and a span. Each of the chord and the span has a bow being summed to form a generally "C" configuration of the airfoil. The generally "C" configuration includes a compound bow in which internal stresses resulting from a thermal temperature gradient are reduced. The structural configuration reduces internal stresses resulting from thermal expansion.

  5. Aerodynamic response of an airfoil section undergoing pitch motion and trailing edge flap deflection: a comparison of simulation methods

    DEFF Research Database (Denmark)

    Bergami, Leonardo; Riziotis, Vasilis A.; Gaunaa, Mac

    2015-01-01

    generated by the airfoil undergoing harmonic pitching motions and harmonic flap deflections. The unsteady aerodynamic coefficients exhibit significant variations over the corresponding steady-state values. The dynamic characteristics of the unsteady response are predicted with an excellent agreement among...

  6. Numerical prediction of shock induced oscillations over a 2D airfoil: Influence of turbulence modelling and test section walls

    International Nuclear Information System (INIS)

    The present study deals with recent numerical results from on-going research conducted at ONERA/DMAE regarding the prediction of transonic flows, for which shock wave/boundary layer interaction is important. When this interaction is strong enough (M ≥ 1.3), shock induced oscillations (SIO) appear at the suction side of the airfoil and lead to the formation of unsteady separated areas. The main issue is then to perform unsteady computations applying appropriate turbulence modelling and relevant boundary conditions with respect to the test case. Computations were performed with the ONERA elsA software and the URANS-type approach, closure relationships being achieved from transport-equation models. Applications are provided for the OAT15A airfoil data base, well documented for unsteady CFD validation (mean and r.m.s. pressure, phase-averaged LDA data, ...). In this paper, the capabilities of turbulence models are evaluated with two 2D URANS strategies, under free-stream or confined conditions. The latter takes into account the adaptive upper and lower wind-tunnel walls. A complete 3D URANS simulation was then performed to demonstrate the real impact of all lateral wind-tunnel walls on such a flow

  7. Second Stage Turbine Bucket Airfoil.

    Science.gov (United States)

    Xu, Liming; Ahmadi, Majid; Humanchuk, David John; Moretto, Nicholas; Delehanty, Richard Edward

    2003-05-06

    The second-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinate values defining the airfoil profile at each distance Z. The X, Y and Z values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket.

  8. Flatback airfoil wind tunnel experiment.

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-04-01

    A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.

  9. Airfoils and method for designing airfoils

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to airfoils and design and design optimization of airfoils, in particular airfoils of rotor blades for wind turbines. One aspect of the invention relates to an airfoil with an external shape provided by an airfoil profile defined by a limited number of parameters, such...... as a set of parameters. Another aspect of the invention relates to a method for designing an airfoil by means of an analytical airfoil profile, said method comprising the step of applying a conformal mapping to a near circle in a near circle plane, wherein the near circle is at least partly expressed...... by means of an analytical function, said conformal mapping transforming the near circle in the near circle plane to the airfoil profile in an airfoil plane. L...

  10. Composite airfoil assembly

    Science.gov (United States)

    Garcia-Crespo, Andres Jose

    2015-03-03

    A composite blade assembly for mounting on a turbine wheel includes a ceramic airfoil and an airfoil platform. The ceramic airfoil is formed with an airfoil portion, a blade shank portion and a blade dovetail tang. The metal platform includes a platform shank and a radially inner platform dovetail. The ceramic airfoil is captured within the metal platform, such that in use, the ceramic airfoil is held within the turbine wheel independent of the metal platform.

  11. An empirically derived basis for calculating the area, rate, and distribution of water-drop impingement on airfoils

    Science.gov (United States)

    Bergrun, Norman R

    1952-01-01

    An empirically derived basis for predicting the area, rate, and distribution of water-drop impingement on airfoils of arbitrary section is presented. The concepts involved represent an initial step toward the development of a calculation technique which is generally applicable to the design of thermal ice-prevention equipment for airplane wing and tail surfaces. It is shown that sufficiently accurate estimates, for the purpose of heated-wing design, can be obtained by a few numerical computations once the velocity distribution over the airfoil has been determined. The calculation technique presented is based on results of extensive water-drop trajectory computations for five airfoil cases which consisted of 15-percent-thick airfoils encompassing a moderate lift-coefficient range. The differential equations pertaining to the paths of the drops were solved by a differential analyzer.

  12. Airfoil shape for flight at subsonic speeds

    Science.gov (United States)

    Whitcomb, Richard T.

    1976-01-01

    An airfoil having an upper surface shaped to control flow accelerations and pressure distribution over the upper surface and to prevent separation of the boundary layer due to shock wave formulation at high subsonic speeds well above the critical Mach number. A highly cambered trailing edge section improves overall airfoil lifting efficiency.

  13. Reinforced Airfoil Shaped Body

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to an airfoil shaped body with a leading edge and a trailing edge extending along the longitudinal extension of the body and defining a profile chord, the airfoil shaped body comprising an airfoil shaped facing that forms the outer surface of the airfoil shaped body...

  14. Airfoil Shape Optimization in Transonic Flow

    International Nuclear Information System (INIS)

    A computationally efficient and adaptable design tool is constructed by coupling a flow analysis code based on Euler equations, with the well established numerical optimization algorithms. Optimization technique involving two analysis methods of Simplex and Rosenbrock have been used. The optimization study involves the minimization of wave drag for two different airfoils with geometric constraints on the airfoil maximum thickness or the cross sectional area along with aerodynamic constraint on lift coefficient. The method is applied to these airfoils transonic flow design points, and the results are compared with the original values. This study shows that the conventional low speed airfoils can be optimized to become supercritical for transonic flight speeds, while existing supercritical airfoils can still be improved further at particular design condition. (author)

  15. Multiple piece turbine engine airfoil with a structural spar

    Science.gov (United States)

    Vance, Steven J.

    2011-10-11

    A multiple piece turbine airfoil having an outer shell with an airfoil tip that is attached to a root with an internal structural spar is disclosed. The root may be formed from first and second sections that include an internal cavity configured to receive and secure the one or more components forming the generally elongated airfoil. The internal structural spar may be attached to an airfoil tip and place the generally elongated airfoil in compression. The configuration enables each component to be formed from different materials to reduce the cost of the materials and to optimize the choice of material for each component.

  16. Airfoil shape for a turbine bucket

    Science.gov (United States)

    Hyde, Susan Marie; By, Robert Romany; Tressler, Judd Dodge; Schaeffer, Jon Conrad; Sims, Calvin Levy

    2005-06-28

    Third stage turbine buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth Table I wherein X and Y values are in inches and the Z values are non-dimensional values from 0 to 0.938 convertible to Z distances in inches by multiplying the Z values by the height of the airfoil in inches. The X and Y values are distances which, when connected by smooth continuing arcs, define airfoil profile sections at each distance Z. The profile sections at each distance Z are joined smoothly to one another to form a complete airfoil shape. The X and Y distances may be scalable as a function of the same constant or number to provide a scaled up or scaled down airfoil section for the bucket. The nominal airfoil given by the X, Y and Z distances lies within an envelop of .+-.0.150 inches in directions normal to the surface of the airfoil.

  17. Third-stage turbine bucket airfoil

    Science.gov (United States)

    Pirolla, Peter Paul; Siden, Gunnar Leif; Humanchuk, David John; Brassfield, Steven Robert; Wilson, Paul Stuart

    2002-01-01

    The third-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinates defining the airfoil profile at each distance Z. The X, Y and Z values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket.

  18. Second-stage turbine bucket airfoil

    Science.gov (United States)

    Wang, John Zhiqiang; By, Robert Romany; Sims, Calvin L.; Hyde, Susan Marie

    2002-01-01

    The second-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in inches in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinate values defining the airfoil profile at each distance Z. The X and Y values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket. The second-stage wheel has sixty buckets.

  19. Report of material and equipment section`s activities at New York Shipbuilding Corporation during fabrication of AXC 167 1/2 starting May 18, 1951. Part 7, Section 3

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, J.R.

    1954-04-28

    This document provides Part VII, Section III and Section IV of the report of the Material and Equipment Section`s activities at the New York Shipbuilding Corporation. The fabrication, inspection, and testing of reactor components is detailed.

  20. Parental modelling, media equipment and screen-viewing among young children: cross-sectional study

    OpenAIRE

    Jago, Russell; Sebire, Simon J.; Lucas, Patricia J.; Turner, Katrina M; Bentley, Georgina F; Goodred, Joanna K; Stewart-Brown, Sarah; Fox, Kenneth R

    2013-01-01

    Objective To examine whether parental screen-viewing, parental attitudes or access to media equipment were associated with the screen-viewing of 6-year-old to 8-year-old children. Design Cross-sectional survey. Setting Online survey. Main outcome Parental report of the number of hours per weekday that they and, separately, their 6-year-old to 8-year-old child spent watching TV, using a games console, a smart-phone and multiscreen viewing. Parental screen-viewing, parental attitudes and pieces...

  1. Parental modelling, media equipment and screen-viewing among young children: cross-sectional study

    Science.gov (United States)

    Jago, Russell; Sebire, Simon J; Lucas, Patricia J; Turner, Katrina M; Bentley, Georgina F; Goodred, Joanna K; Stewart-Brown, Sarah; Fox, Kenneth R

    2013-01-01

    Objective To examine whether parental screen-viewing, parental attitudes or access to media equipment were associated with the screen-viewing of 6-year-old to 8-year-old children. Design Cross-sectional survey. Setting Online survey. Main outcome Parental report of the number of hours per weekday that they and, separately, their 6-year-old to 8-year-old child spent watching TV, using a games console, a smart-phone and multiscreen viewing. Parental screen-viewing, parental attitudes and pieces of media equipment were exposures. Results Over 75% of the parents and 62% of the children spent more than 2 h/weekday watching TV. Over two-thirds of the parents and almost 40% of the children spent more than an hour per day multiscreen viewing. The mean number of pieces of media equipment in the home was 5.9 items, with 1.3 items in the child's bedroom. Children who had parents who spent more than 2 h/day watching TV were over 7.8 times more likely to exceed the 2 h threshold. Girls and boys who had a parent who spent an hour or more multiscreen viewing were 34 times more likely to also spend more than an hour per day multiscreen viewing. Media equipment in the child's bedroom was associated with higher TV viewing, computer time and multiscreen viewing. Each increment in the parental agreement that watching TV was relaxing for their child was associated with a 49% increase in the likelihood that the child spent more than 2 h/day watching TV. Conclusions Children who have parents who engage in high levels of screen-viewing are more likely to engage in high levels of screen-viewing. Access to media equipment, particularly in the child's bedroom, was associated with higher levels of screen-viewing. Family-based strategies to reduce screen-viewing and limit media equipment access may be important ways to reduce child screen-viewing. PMID:23619088

  2. The design of equipment for optical power measurement in FSO link beam cross-section

    Science.gov (United States)

    Latal, Jan; David, Tomas; Wilfert, Otakar; Kolka, Zdenek; Koudelka, Petr; Hanacek, Frantisek; Vitasek, Jan; Siska, Petr; Skapa, Jan; Vasinek, Vladimir

    2012-06-01

    The free space optical links have found their major application in today's technological society. The demand for quality broadband is a must for all types of end users in these times. Because of the large jamming from wireless radio networks in non-licensed ISM bands, the free space optical links provide bridging of some densely populated urban areas. Their advantage is the high transmission rate for relatively long distances. However, the disadvantage is the dependence of free space optical links on atmospheric influences. Aired collimated optical beam passes through the atmospheric transmission environment and by its influence cause the deformation of the optical beam. Author's team decided to construct a special measuring device for measurement of optical power in FSO link beam cross-section. The equipment is mobile and can be rearranged and adjust according to the given location and placement of the FSO link at any time. The article describes the individual structural elements of the measuring equipment, its controlling and application for evaluation and adjustment of measuring steps. The graphs from optical power measurements in the beam cross-section of professional FSO links are presented at the end.

  3. Airfoil System for Cruising Flight

    Science.gov (United States)

    Shams, Qamar A. (Inventor); Liu, Tianshu (Inventor)

    2014-01-01

    An airfoil system includes an airfoil body and at least one flexible strip. The airfoil body has a top surface and a bottom surface, a chord length, a span, and a maximum thickness. Each flexible strip is attached along at least one edge thereof to either the top or bottom surface of the airfoil body. The flexible strip has a spanwise length that is a function of the airfoil body's span, a chordwise width that is a function of the airfoil body's chord length, and a thickness that is a function of the airfoil body's maximum thickness.

  4. Multiple piece turbine airfoil

    Science.gov (United States)

    Kimmel, Keith D; Wilson, Jr., Jack W.

    2010-11-02

    A turbine airfoil, such as a rotor blade or a stator vane, for a gas turbine engine, the airfoil formed as a shell and spar construction with a plurality of dog bone struts each mounted within openings formed within the shell and spar to allow for relative motion between the spar and shell in the airfoil chordwise direction while also forming a seal between adjacent cooling channels. The struts provide the seal as well as prevent bulging of the shell from the spar due to the cooling air pressure.

  5. Closed loop steam cooled airfoil

    Science.gov (United States)

    Widrig, Scott M.; Rudolph, Ronald J.; Wagner, Gregg P.

    2006-04-18

    An airfoil, a method of manufacturing an airfoil, and a system for cooling an airfoil is provided. The cooling system can be used with an airfoil located in the first stages of a combustion turbine within a combined cycle power generation plant and involves flowing closed loop steam through a pin array set within an airfoil. The airfoil can comprise a cavity having a cooling chamber bounded by an interior wall and an exterior wall so that steam can enter the cavity, pass through the pin array, and then return to the cavity to thereby cool the airfoil. The method of manufacturing an airfoil can include a type of lost wax investment casting process in which a pin array is cast into an airfoil to form a cooling chamber.

  6. Supercritical Airfoil Coordinates

    Data.gov (United States)

    National Aeronautics and Space Administration — Rectangular Supercritical Wing (Ricketts) - design and measured locations are provided in an Excel file RSW_airfoil_coordinates_ricketts.xls . One sheet is with Non...

  7. Residual lifetime calculations for the equipment and pipes of WWER type nuclear power plants (1st draft). Section IV

    International Nuclear Information System (INIS)

    The standards documentation of the Association of Mechanical Engineers, Section IV, 'Residual lifetime calculations for the equipment and pipes of WWER type nuclear power plants', provides guidelines and requirements for (i) residual lifetime assessment for apparatus, pipes and supports at WWER type nuclear power plants with respect to their resistance to sudden failure and fatigue damage and with respect to the occurrence of defects detected during in-service inspections; (ii) residual lifetime assessment for apparatus, pipes and supports at WWER type nuclear power plants after component repair, replacement or innovation; and (iii) preparation of documents relating to the continuous gradual exhaustion of the lifetime of apparatus, pipes, and supports at WWER 440 MW and WWER 1000 MW type nuclear power plants and assessment of their residual lifetime. The standards documentation is based on the philosophy of ASME Code Section XI and contains some additional guidelines. The report is divided into the following chapters: General principles, terminology, definitions; General requirements for residual lifetime calculations; Equipment residual lifetime calculation procedure; Equipment residual lifetime assessment with regard to resistance against sudden failure; Assessment of equipment 'fatigue' lifetime; Assessment of equipment 'corrosion mechanical lifetime'; Assessment of the tolerability of defects detected during in-service inspections and residual lifetime assessment for equipment containing such defects; and final assessment of the residual lifetime of equipment. Details are given in 12 Annexes. (P.A.)

  8. Tail Rotor Airfoils Stabilize Helicopters, Reduce Noise

    Science.gov (United States)

    2010-01-01

    Founded by former Ames Research Center engineer Jim Van Horn, Van Horn Aviation of Tempe, Arizona, built upon a Langley Research Center airfoil design to create a high performance aftermarket tail rotor for the popular Bell 206 helicopter. The highly durable rotor has a lifetime twice that of the original equipment manufacturer blade, reduces noise by 40 percent, and displays enhanced performance at high altitudes. These improvements benefit helicopter performance for law enforcement, military training, wildfire and pipeline patrols, and emergency medical services.

  9. Wind turbine airfoil catalogue

    Energy Technology Data Exchange (ETDEWEB)

    Bertagnolio, F.; Soerensen, N.; Johansen, J.; Fuglsang, P.

    2001-08-01

    The aim of this work is two-sided. Firstly, experimental results obtained for numerous sets of airfoil measurements (mainly intended for wind turbine applications) are collected and compared with computational results from the 2D Navier-Stokes solver EllipSys2D, as well as results from the panel method code XFOIL. Secondly, we are interested in validating the code EllipSys2D and finding out for which air-foils it does not perform well compared to the experiments, as well as why, when it does so. The airfoils are classified according to the agreement between the numerical results and experimental data. A study correlating the available data and this classification is performed. It is found that transition modelling is to a large extent responsible for the poor quality of the computational results for most of the considered airfoils. The transition model mechanism that leads to these discrepancies is identified. Some advices are given for elaborating future airfoil design processes that would involve the numerical code EllipSys2D in particular, and transition modelling in general. (au)

  10. Robust, Optimal Subsonic Airfoil Shapes

    Science.gov (United States)

    Rai, Man Mohan

    2014-01-01

    A method has been developed to create an airfoil robust enough to operate satisfactorily in different environments. This method determines a robust, optimal, subsonic airfoil shape, beginning with an arbitrary initial airfoil shape, and imposes the necessary constraints on the design. Also, this method is flexible and extendible to a larger class of requirements and changes in constraints imposed.

  11. Turbine airfoil with controlled area cooling arrangement

    Science.gov (United States)

    Liang, George

    2010-04-27

    A gas turbine airfoil (10) includes a serpentine cooling path (32) with a plurality of channels (34,42,44) fluidly interconnected by a plurality of turns (38,40) for cooling the airfoil wall material. A splitter component (50) is positioned within at least one of the channels to bifurcate the channel into a pressure-side channel (46) passing in between the outer wall (28) and the inner wall (30) of the pressure side (24) and a suction-side channel (48) passing in between the outer wall (28) and the inner wall (30) of the suction side (26) longitudinally downstream of an intermediate height (52). The cross-sectional area of the pressure-side channel (46) and suction-side channel (48) are thereby controlled in spite of an increasing cross-sectional area of the airfoil along its longitudinal length, ensuring a sufficiently high mach number to provide a desired degree of cooling throughout the entire length of the airfoil.

  12. Potential flow analysis of glaze ice accretions on an airfoil

    Science.gov (United States)

    Zaguli, R. J.

    1984-01-01

    The results of an analytical/experimental study of the flow fields about an airfoil with leading edge glaze ice accretion shapes are presented. Tests were conducted in the Icing Research Tunnel to measure surface pressure distributions and boundary layer separation reattachment characteristics on a general aviation wing section to which was affixed wooden ice shapes which approximated typical glaze ice accretions. Comparisons were made with predicted pressure distributions using current airfoil analysis codes as well as the Bristow mixed analysis/design airfoil panel code. The Bristow code was also used to predict the separation reattachment dividing streamline by inputting the appropriate experimental surface pressure distribution.

  13. Second-order subsonic airfoil theory including edge effects

    Science.gov (United States)

    Van Dyke, Milton D

    1956-01-01

    Several recent advances in plane subsonic flow theory are combined into a unified second-order theory for airfoil sections of arbitrary shape. The solution is reached in three steps: the incompressible result is found by integration, it is converted into the corresponding subsonic compressible result by means of the second-order compressibility rule, and it is rendered uniformly valid near stagnation points by further rules. Solutions for a number of airfoils are given and are compared with the results of other theories and of experiment. A straight-forward computing scheme is outlined for calculating the surface velocities and pressures on any airfoil at any angle of attack

  14. Multi-Element Airfoil System

    Science.gov (United States)

    Turner, Travis L. (Inventor); Khorrami, Mehdi R. (Inventor); Lockard, David P. (Inventor); McKenney, Martin J. (Inventor); Atherley, Raymond D. (Inventor); Kidd, Reggie T. (Inventor)

    2014-01-01

    A multi-element airfoil system includes an airfoil element having a leading edge region and a skin element coupled to the airfoil element. A slat deployment system is coupled to the slat and the skin element, and is capable of deploying and retracting the slat and the skin element. The skin element substantially fills the lateral gap formed between the slat and the airfoil element when the slat is deployed. The system further includes an uncoupling device and a sensor to remove the skin element from the gap based on a critical angle-of-attack of the airfoil element. The system can alternatively comprise a trailing edge flap, where a skin element substantially fills the lateral gap between the flap and the trailing edge region of the airfoil element. In each case, the skin element fills a gap between the airfoil element and the deployed flap or slat to reduce airframe noise.

  15. The Effects of the Critical Ice Accretion on Airfoil and Wing Performance

    Science.gov (United States)

    Selig, Michael S.; Bragg, Michael B.; Saeed, Farooq

    1998-01-01

    In support of the NASA Lewis Modern Airfoils Ice Accretion Test Program, the University of Illinois at Urbana-Champaign provided expertise in airfoil design and aerodynamic analysis to determine the aerodynamic effect of ice accretion on modern airfoil sections. The effort has concentrated on establishing a design/testing methodology for "hybrid airfoils" or "sub-scale airfoils," that is, airfoils having a full-scale leading edge together with a specially designed and foreshortened aft section. The basic approach of using a full-scale leading edge with a foreshortened aft section was considered to a limited extent over 40 years ago. However, it was believed that the range of application of the method had not been fully exploited. Thus a systematic study was being undertaken to investigate and explore the range of application of the method so as to determine its overall potential.

  16. First-stage high pressure turbine bucket airfoil

    Science.gov (United States)

    Brown, Theresa A.; Ahmadi, Majid; Clemens, Eugene; Perry, II, Jacob C.; Holiday, Allyn K.; Delehanty, Richard A.; Jacala, Ariel Caesar

    2004-05-25

    The first-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinates defining the airfoil profile at each distance Z. The X, Y and Z values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket.

  17. Computational design and analysis of flatback airfoil wind tunnel experiment.

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-03-01

    A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.

  18. EUDP Project: Low Noise Airfoil - Final Report

    DEFF Research Database (Denmark)

    to develop and implement a design procedure to manufacture airfoil profiles with low noise emission. The project involved two experimental campaigns: one in the LM Wind Power wind tunnel, a classical aerodynamic wind tunnel, in Lunderskov (DK), the second one in the Virginia Tech Stability Wind...... Tunnel at the Aerospace and Ocean Engineering Department of Virginia Tech (Blacksburg, VA,(USA), also a classical aerodynamic wind tunnel but equipped with an anechoic chamber that allow to perform acoustic measurements. On the theoretical side, the above experiments yield a series of model validations......This document summarizes the scientific results achieved during the EUDP-funded project `Low-Noise Airfoil'. The goals of this project are, on one side to develop a measurement technique that permits the evaluation of trailing edge noise in a classical aerodynamic wind tunnel, and on the other side...

  19. Wind turbine airfoil catalogue

    DEFF Research Database (Denmark)

    Bertagnolio, F.; Sørensen, Niels N.; Johansen, Jeppe;

    2001-01-01

    The aim of this work is two-sided. Firstly, experimental results obtained for numerous sets of airfoil measurements (mainly intended for wind turbine applications) are collected and compared with computational results from the 2D Navier-Stokes solverEllipSys2D, as well as results from the panel...

  20. Airfoils in Turbulent Inflow

    DEFF Research Database (Denmark)

    Gilling, Lasse

    Wind turbines operate in inflow turbulence whether it originates from the shear in the atmospheric boundary layer or from the wake of other wind turbines. Consequently, the airfoils of the wings experience turbulence in the inflow. The main topic of this thesis is to investigate the effect of...

  1. Selection and Research on Transition Tape in Wind-Turbine Airfoil Section Wind Tunnel Experiment%风力机翼型风洞实验中粗糙带形式的选择研究*

    Institute of Scientific and Technical Information of China (English)

    魏闯; 高永卫; 肖春生

    2013-01-01

    Due to the limitation of model demension and experimental speed, the experimental Reynolds number in the low speed wind tunnel is usually less than the practical value of airfoil section of wind turbine. This will make the transition location difference between experimental and actual situation. For the purpose of simulating real condition, fixed transition performed with transition tape is often adopted in wind tunnel experiments. Practice shows that the types and parameters of transition tape have an important impact on the experimental results. It needs to be chosen very carefully. In addition, because the wind turbine blade operated in the field for long time, contaminations accumulate on it and increase its surface roughness. This contamination has a great role on the rotor performance; the impact of it has not been well studied. This paper gives a summary of wind tunnel test results and discusses the actions of four types of transition tape of ZZ,ZZT,T and H, and additional effects on the wind turbine airfoil section. The results show that ZZT-type has well transition effect with the least additional drag and H-type has a better simulation for the impact of the insect compacts in the wind turbine blade airfoil experiment.%  由于模型尺寸与实验风速的限制,低速翼型风洞实验雷诺数通常小于实际值,造成翼面转捩点偏后,翼型表面流动与实际不相符。为了尽量真实模拟实际流动,风洞实验一般采用粗糙带在翼型表面前缘进行固定转捩。实践表明,粗糙带的种类及其参数对实验结果有重要的影响,需要非常仔细地选择。另外,由于风力机叶片长期在野外工作,污染造成表面粗糙度增加,这部分的影响一直没有得到很好的研究。本文采用风洞实验的方法,对ZZR、ZZT、T和H型等四种粗糙带在风力机翼型风洞实验中的作用及附加影响进行了研究。研究结果表明,在

  2. Effect of camber and thickness on the aerodynamic properties of an airfoil in ground proximity

    International Nuclear Information System (INIS)

    A linear vortex panel method is extended to include the effect of ground proximity on the aerodynamic properties of two dimensional airfoils. The image method is used to model the ground effect. According to the results, lift coefficient of an airfoil may increase or decrease in ground effect based on a combinative effect of its camber, thickness, angle of attack and ground clearance. Airfoils with different section parameters are analysed and their relative effectiveness are compared

  3. Vertical axis wind turbine airfoil

    Science.gov (United States)

    Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

    2012-12-18

    A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

  4. Shape Changing Airfoil

    Science.gov (United States)

    Ott, Eric A.

    2005-01-01

    Scoping of shape changing airfoil concepts including both aerodynamic analysis and materials-related technology assessment effort was performed. Three general categories of potential components were considered-fan blades, booster and compressor blades, and stator airfoils. Based on perceived contributions to improving engine efficiency, the fan blade was chosen as the primary application for a more detailed assessment. A high-level aerodynamic assessment using a GE90-90B Block 4 engine cycle and fan blade geometry indicates that blade camber changes of approximately +/-4deg would be sufficient to result in fan efficiency improvements nearing 1 percent. Constraints related to flight safety and failed mode operation suggest that use of the baseline blade shape with actuation to the optimum cruise condition during a portion of the cycle would be likely required. Application of these conditions to the QAT fan blade and engine cycle was estimated to result in an overall fan efficiency gain of 0.4 percent.

  5. Transonic airfoil and axial flow rotary machine

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Naonori; Iwatani, Junji

    2015-09-01

    Sectional profiles close to a tip 124 and a part between a midportion 125 and a hub 123 are shifted to the upstream of an operating fluid flow in a sweep direction. Accordingly, an S shape is formed in which the tip 124 and the part between the midportion 125 and the hub 123 protrude. As a result, it is possible reduce various losses due to shook, waves, thereby forming a transonic airfoil having an excellent aerodynamic characteristic.

  6. DECON BOY: an easy-to-use mobile equipment for decontamination of components and small system sections

    International Nuclear Information System (INIS)

    The DECON BOY is a compact, mobile decontamination appliance for the decontamination of removed components or even small system sections. For removed components it operates in a closed circuit after placing the parts to be decontaminated in a decontamination tank. In the case of system sections, the equipment is placed close to the system to be decontaminated and connected by special hoses. The decontamination principle bases on the Siemens CORD/CORD UV process. In its design, particular attention has been paid on easy and economical operation. It uses the ''dishwasher'' operation principle: once the machine is started, the operation proceeds fully automatically. The equipment has a modular design, adapting to all specific plant requirements and space available, and enabling also the incorporation of other decontamination techniques. It provides for minimal occupational exposures associated to the decontamination work, far less than with standard techniques in use to data. The application experience in the field show excellent results. After decontamination, inspection and testing of components can be performed in considerably lower radiation fields. Decontamination factors higher than 100 and up to 40,000 can be readily achieved. In this presentation, the main constructive and functional features of the equipment are described, as well as application examples and results obtained. (author)

  7. 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...

  8. Turbine airfoil to shround attachment

    Science.gov (United States)

    Campbell, Christian X; Morrison, Jay A; James, Allister W; Snider, Raymond G; Eshak, Daniel M; Marra, John J; Wessell, Brian J

    2014-05-06

    A turbine airfoil (31) with an end portion (42) that tapers (44) toward the end (43) of the airfoil. A ridge (46) extends around the end portion. It has proximal (66) and distal (67) sides. A shroud platform (50) is bi-cast onto the end portion around the ridge without bonding. Cooling shrinks the platform into compression (62) on the end portion (42) of the airfoil. Gaps between the airfoil and platform are formed using a fugitive material (56) in the bi-casting stage. These gaps are designed in combination with the taper angle (44) to accommodate differential thermal expansion while maintaining a gas seal along the contact surfaces. The taper angle (44) may vary from lesser on the pressure side (36) to greater on the suction side (38) of the airfoil. A collar portion (52) of the platform provides sufficient contact area for connection stability.

  9. Experimental investigation of a transonic potential flow around a symmetric airfoil

    Science.gov (United States)

    Hiller, W. J.; Meier, G. E. A.

    1981-01-01

    Experimental flow investigations on smooth airfoils were done using numerical solutions for transonic airfoil streaming with shockless supersonic range. The experimental flow reproduced essential sections of the theoretically computed frictionless solution. Agreement is better in the expansion part of the of the flow than in the compression part. The flow was nearly stationary in the entire velocity range investigated.

  10. WIND TUNNEL RESEARCH ON THE INFLUENCE OF ACTIVE AIRFLOW ON THE LIFT FORCE GENERATED BY THE AIRFOIL

    Directory of Open Access Journals (Sweden)

    Paweł Magryta

    2013-09-01

    Full Text Available The paper discusses the results of wind tunnel tests of airfoils with additional active airflow applied to their upper surfaces. These studies were carried out for a range of velocities up to 28 m/s in an open wind tunnel. Several types of airfoils selected for the examination feature different geometries and are widely applied in today’s aviation industry. The changes in the lift and drag force generated by these airfoils were recorded during the study. The test bench for the tests was equipped with a compressor and a vacuum pump to enable airflow through some holes on the airfoil upper surface. A rapid prototyping method and a 3D printer based on a powder printing technique were applied to print the airfoils. All of their surfaces were subject to surface grinding to smooth their external surfaces. The wind tunnel tests with and without active airflow applied to airfoils are summarised in the paper.

  11. Conjugate Heat transfer Analysis of helical fins with airfoil crosssection and its comparison with existing circular fin design for air cooled engines employing constant rectangular cross-section

    Directory of Open Access Journals (Sweden)

    Ashwin Shridhar

    2015-06-01

    Full Text Available Air Cooled Engines have been used in a variety of applications, ranging from airplanes to motorbikes and even stationary or portable engines. Since modern automobiles and airplanes use engines delivering more power, they have to be cooled more efficiently due to which a more complex water cooling system is used for cooling engines with large displacements. Hence air cooling is becoming a thing of the past, especially in the aviation sector due to the advent of more efficient gas turbine engines. However air cooled internal combustion engines are still being used in a wide variety of two-wheelers ranging from small single cylinder engines to heavy duty liter class V-twins and Inline fours, due to the non-practicalities associated with the installment of a bulky water cooling system in two-wheelers. So one can ascertain that there is a scope for improving the efficiency of air cooled engines even further. The objective of this paper is to analyze currently existing fin design employed in most of the air cooled engines and improve it by changing the cross-section to a streamlined one and also making the fins in a helical orientation as opposed to the regular circular fins employed. Our analysis comprises of a computational fluid dynamics study of both the fin models with identical dimensions and simulated in the same environment using ANSYS FLUENT 15 software and we attempt to compare their performance using the temperature and heat transfer coefficient distribution plots obtained.

  12. Prediction of the Effect of Vortex Generators on Airfoil Performance

    DEFF Research Database (Denmark)

    Sørensen, Niels N.; Zahle, Frederik; Bak, Christian; Vronsky, T.

    2014-01-01

    Vortex Generators (VGs) are widely used by the wind turbine industry, to control the flow over blade sections. The present work describes a computational fluid dynamic procedure that can handle a geometrical resolved VG on an airfoil section. After describing the method, it is applied to two...... different airfoils at a Reynolds number of 3 million, the FFA- W3-301 and FFA-W3-360, respectively. The computations are compared with wind tunnel measurements from the Stuttgart Laminar Wind Tunnel with respect to lift and drag variation as function of angle of attack. Even though the method does not...

  13. Airfoil nozzle and shroud assembly

    Science.gov (United States)

    Shaffer, James E.; Norton, Paul F.

    1997-01-01

    An airfoil and nozzle assembly including an outer shroud having a plurality of vane members attached to an inner surface and having a cantilevered end. The assembly further includes a inner shroud being formed by a plurality of segments. Each of the segments having a first end and a second end and having a recess positioned in each of the ends. The cantilevered end of the vane member being positioned in the recess. The airfoil and nozzle assembly being made from a material having a lower rate of thermal expansion than that of the components to which the airfoil and nozzle assembly is attached.

  14. Aerodynamic performance of transonic and subsonic airfoils: Effects of surface roughness, turbulence intensity, Mach number, and streamline curvature-airfoil shape

    Science.gov (United States)

    Zhang, Qiang

    The effects of surface roughness, turbulence intensity, Mach number, and streamline curvature-airfoil shape on the aerodynamic performance of turbine airfoils are investigated in compressible, high speed flows. The University of Utah Transonic Wind Tunnel is employed for the experimental part of the study. Two different test sections are designed to produce Mach numbers, Reynolds numbers, passage mass flow rates, and physical dimensions, which match values along turbine blades in operating engines: (i) a nonturning test section with a symmetric airfoil, and (ii) a cascade test section with a cambered turbine vane. The nonuniform, irregular, three-dimensional surface roughness is characterized using the equivalent sand grain roughness size. Changing the airfoil surface roughness condition has a substantial effect on wake profiles of total pressure loss coefficients, normalized Mach number, normalized kinetic energy, and on the normalized and dimensional magnitudes of Integrated Aerodynamic Losses produced by the airfoils. Comparisons with results for a symmetric airfoil and a cambered vane show that roughness has more substantial effects on losses produced by the symmetric airfoil than the cambered vane. Data are also provided that illustrate the larger loss magnitudes are generally present with flow turning and cambered airfoils, than with symmetric airfoils. Wake turbulence structure of symmetric airfoils and cambered vanes are also studied experimentally. The effects of surface roughness and freestream turbulence levels on wake distributions of mean velocity, turbulence intensity, and power spectral density profiles and vortex shedding frequencies are quantified one axial chord length downstream of the test airfoils. As the level of surface roughness increases, all wake profile quantities broaden significantly and nondimensional vortex shedding frequencies decrease. Wake profiles produced by the symmetric airfoil are more sensitive to variations of surface

  15. Computational Analysis of Propulsion Performance of Modified Pitching Motion Airfoils in Laminar Flow

    Directory of Open Access Journals (Sweden)

    Yonghui Xie

    2014-01-01

    Full Text Available The thrust generation performance of airfoils with modified pitching motion was investigated by computational fluid dynamics (CFD modeling two-dimensional laminar flow at Reynolds number of 104. The effect of shift distance of the pitch axis outside the chord line (R, reduced frequency (k, pitching amplitude (θ, pitching profile, and airfoil shape (airfoil thickness and camber on the thrust generated and efficiency were studied. The results reveal that the increase in R and k leads to an enhancement in thrust generation and a decrease in propulsive efficiency. Besides, there exists an optimal range of θ for the maximum thrust and the increasing θ induces a rapid decrease in propulsive efficiency. Six adjustable parameters (K were employed to realize various nonsinusoidal pitching profiles. An increase in K results in more thrust generated at the cost of decreased propulsive efficiency. The investigation of the airfoil shape effect reveals that there exists an optimal range of airfoil thickness for the best propulsion performance and that the vortex structure is strongly influenced by the airfoil thickness, while varying the camber or camber location of airfoil sections offers no benefit in thrust generation over symmetric airfoil sections.

  16. Derivation of airfoil characteristics for the LM 19.1 blade based on 3D CFD rotor calculations

    Energy Technology Data Exchange (ETDEWEB)

    Bak, C.; Soerensen, N.N.; Madsen, H.A. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    Airfoil characteristics for the LM 19.1 blade are derived from 3D CFD computations on a full-scale 41-m rotor. Based on 3D CFD the force distributions on the blades are determined, from which airfoil characteristics are derived using the momentum theory. The final airfoil characteristics are constructed using both wind tunnel measurements and 3D CFD. Compared to 2D wind tunnel measurements they show a low lift in stall for the airfoil sections at the tip. At the airfoil sections at the inner part of the blade, they show a high lift in stall. At about 60% radius the lift agrees well to 2D wind tunnel measurements. Aero-elastic calculations using the final airfoil characteristics show good agreement to measured power and flap moments. Furthermore, a fatigue load analysis shows a reduction of up to 15% of the load compared to commonly used data. (au)

  17. On the performance of equipment inspections by authorized experts according to sections 4 and 18 of the X-Ray Ordinance. Comments. 2. rev. ed.

    International Nuclear Information System (INIS)

    The book's general part provides a reproduction of, and comment on, section 4, subsections 1 and 5, and section 18, No. 4 of the X-ray Ordinance, as well as reproductions of the relevant directive and of section 50 of the law governing medical products. In its special part, reproducible procedures for inspections by operators, experts and government agencies are described separately for non-medical equipment, stationary and mobile X-ray equipments visualizing gross and fine structures, for fully shielded and highly shielded units, equipments for medical screening at schools as well as medical and dental X-ray equipments (radiographic units, combined radiographic and fluoroscopic units, C-arch units, dental radiographic units equipped with a tube, special radiographic equipment for dentists, CT units, radiotherapeutic equipment, units for bone density measurements, veterinary X-ray equipment). In the appendix, a survey is given of the most important guidelines and standards (updated until 1994) for the performance of inspections by experts. (HP)

  18. Analysis of a theoretically optimized transonic airfoil

    Science.gov (United States)

    Lores, M. E.; Burdges, K. P.; Shrewsbury, G. D.

    1978-01-01

    Numerical optimization was used in conjunction with an inviscid, full potential equation, transonic flow analysis computer code to design an upper surface contour for a conventional airfoil to improve its supercritical performance. The modified airfoil was tested in a compressible flow wind tunnel. The modified airfoil's performance was evaluated by comparison with test data for the baseline airfoil and for an airfoil developed by optimization of leading edge of the baseline airfoil. While the leading edge modification performed as expected, the upper surface re-design did not produce all of the expected performance improvements. Theoretical solutions computed using a full potential, transonic airfoil code corrected for viscosity were compared to experimental data for the baseline airfoil and the upper surface modification. These correlations showed that the theory predicted the aerodynamics of the baseline airfoil fairly well, but failed to accurately compute drag characteristics for the upper surface modification.

  19. Nozzle airfoil having movable nozzle ribs

    Science.gov (United States)

    Yu, Yufeng Phillip; Itzel, Gary Michael

    2002-01-01

    A nozzle vane or airfoil structure is provided in which the nozzle ribs are connected to the side walls of the vane or airfoil in such a way that the ribs provide the requisite mechanical support between the concave side and convex side of the airfoil but are not locked in the radial direction of the assembly, longitudinally of the airfoil. The ribs may be bi-cast onto a preformed airfoil side wall structure or fastened to the airfoil by an interlocking slide connection and/or welding. By attaching the nozzle ribs to the nozzle airfoil metal in such a way that allows play longitudinally of the airfoil, the temperature difference induced radial thermal stresses at the nozzle airfoil/rib joint area are reduced while maintaining proper mechanical support of the nozzle side walls.

  20. Airfoil characteristics for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Bak, C.; Fuglsang, P.; Soerensen, N.N.; Aagaard Madsen, H. [Risoe National Lab., Roskilde (Denmark); Wen Zhong Shen; Noerkaer Soerensen, J. [Technical Univ. of Denmark, Lyngby (Denmark)

    1999-03-01

    Airfoil characteristics for use in the Blade Element Momentum (BEM) method calculating the forces on Horizontal Axis Wind Turbines (HAWT) are derived by use of systematic methods. The investigation and derivation of the airfoil characteristics are based on four different methods: 1) Inverse momentum theory, 2) Actuator disc theory, 3) Numerical optimisation and 4) Quasi-3D CFD computations. The two former methods are based on 3D CFD computations and wind tunnel measurements on a 41-m full-scale rotor with LM 19.1 blades. The derived airfoil characteristics show that the lift coefficient in stall at the tip is low and that it is high at the root compared to 2D airfoil characteristics. The use of these characteristics in aeroelastic calculations shows a good agreement in power and flap moments with measurements. Furthermore, a fatigue analysis shows a reduction in the loads of up to 15 % compared to a commonly used set of airfoil characteristics. The numerical optimisation is based on both the 3D CFD computations and measurements on a 41-m rotor with LM 19.1 and LM 19.0 blades, respectively. The method requires power and loads from a turbine and is promising since a set of lift and drag curves is derived that can be used to calculate mean values of power and loads. The lift in stall at the tip is low and at the root it is high compared to 2D airfoil characteristics. In particular the power curves were well calculated by use of the optimised airfoil characteristics. In the quasi-3D CFD computations, the airfoil characteristics are derived directly. This Navier-Stokes model takes into account rotational and 3D effects. The model enables the study of the rotational effect of a rotor blade at computing costs similar to what is typical for 2D airfoil calculations. The depicted results show that the model is capable of determining the correct qualitative behaviour for airfoils subject to rotation. The method shows that lift is high at the root compared to 2D airfoil

  1. 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

  2. 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...

  3. 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...

  4. Musculoskeletal pain among critical-care nurses by availability and use of patient lifting equipment: An analysis of cross-sectional survey data

    OpenAIRE

    Lee, SJ; Faucett, J; Gillen, M; Krause, N.

    2013-01-01

    Background: Patient handling is a major risk factor for musculoskeletal injuries among nurses. Lifting equipment is a main component of safe patient handling programs that aim to prevent musculoskeletal injury. However, the actual levels of lift availability and usage are far from optimal. Objective: To examine the effect of patient lifting equipment on musculoskeletal pain by level of lift availability and lift use among critical-care nurses. Design and participants: A cross-sectional postal...

  5. Shape optimization of corrugated airfoils

    Science.gov (United States)

    Jain, Sambhav; Bhatt, Varun Dhananjay; Mittal, Sanjay

    2015-12-01

    The effect of corrugations on the aerodynamic performance of a Mueller C4 airfoil, placed at a 5° angle of attack and Re=10{,}000, is investigated. A stabilized finite element method is employed to solve the incompressible flow equations in two dimensions. A novel parameterization scheme is proposed that enables representation of corrugations on the surface of the airfoil, and their spontaneous appearance in the shape optimization loop, if indeed they improve aerodynamic performance. Computations are carried out for different location and number of corrugations, while holding their height fixed. The first corrugation causes an increase in lift and drag. Each of the later corrugations leads to a reduction in drag. Shape optimization of the Mueller C4 airfoil is carried out using various objective functions and optimization strategies, based on controlling airfoil thickness and camber. One of the optimal shapes leads to 50 % increase in lift coefficient and 23 % increase in aerodynamic efficiency compared to the Mueller C4 airfoil.

  6. Airfoil deposition model

    Science.gov (United States)

    Kohl, F. J.

    1982-01-01

    The methodology to predict deposit evolution (deposition rate and subsequent flow of liquid deposits) as a function of fuel and air impurity content and relevant aerodynamic parameters for turbine airfoils is developed in this research. The spectrum of deposition conditions encountered in gas turbine operations includes the mechanisms of vapor deposition, small particle deposition with thermophoresis, and larger particle deposition with inertial effects. The focus is on using a simplified version of the comprehensive multicomponent vapor diffusion formalism to make deposition predictions for: (1) simple geometry collectors; and (2) gas turbine blade shapes, including both developing laminar and turbulent boundary layers. For the gas turbine blade the insights developed in previous programs are being combined with heat and mass transfer coefficient calculations using the STAN 5 boundary layer code to predict vapor deposition rates and corresponding liquid layer thicknesses on turbine blades. A computer program is being written which utilizes the local values of the calculated deposition rate and skin friction to calculate the increment in liquid condensate layer growth along a collector surface.

  7. Preliminary Investigation of Certain Laminar-Flow Airfoils for Application at High Speeds and Reynolds Numbers

    Science.gov (United States)

    Jacobs, E.N.; Abbott, Ira H.; von Doenhoff, A.E.

    1939-01-01

    In order to extend the useful range of Reynolds numbers of airfoils designed to take advantage of the extensive laminar boundary layers possible in an air stream of low turbulence, tests were made of the NACA 2412-34 and 1412-34 sections in the NACA low-turbulence tunnel. Although the possible extent of the laminar boundary layer on these airfoils is not so great as for specially designed laminar-flow airfoils, it is greater than that for conventional airfoils, and is sufficiently extensive so that at Reynolds numbers above 11,000,000 the laminar region is expected to be limited by the permissible 'Reynolds number run' and not by laminar separation as is the case with conventional airfoils. Drag measurements by the wake-survey method and pressure-distribution measurements were made at several lift coefficients through a range of Reynolds numbers up to 11,400,000. The drag scale-effect curve for the NACA 1412-34 is extrapolated to a Reynolds number of 30,000,000 on the basis of theoretical calculations of the skin friction. Comparable skin-friction calculations were made for the NACA 23012. The results indicate that, for certain applications at moderate values of the Reynolds number, the NACA 1412-34 and 2412-34 airfoils offer some advantages over such conventional airfoils as the NACA 23012. The possibility of maintaining a more extensive laminar boundary layer on these airfoils should result in a small drag reduction, and the absence of pressure peaks allows higher speeds to be reached before the compressibility burble is encountered. At lower Reynold numbers, below about 10,000,000, these airfoils have higher drags than airfoils designed to operate with very extensive laminar boundary layers.

  8. Advanced Airfoils Boost Helicopter Performance

    Science.gov (United States)

    2007-01-01

    Carson Helicopters Inc. licensed the Langley RC4 series of airfoils in 1993 to develop a replacement main rotor blade for their Sikorsky S-61 helicopters. The company's fleet of S-61 helicopters has been rebuilt to include Langley's patented airfoil design, and the helicopters are now able to carry heavier loads and fly faster and farther, and the main rotor blades have twice the previous service life. In aerial firefighting, the performance-boosting airfoils have helped the U.S. Department of Agriculture's Forest Service control the spread of wildfires. In 2003, Carson Helicopters signed a contract with Ducommun AeroStructures Inc., to manufacture the composite blades for Carson Helicopters to sell

  9. Airfoil shape for a turbine nozzle

    Science.gov (United States)

    Burdgick, Steven Sebastian; Patik, Joseph Francis; Itzel, Gary Michael

    2002-01-01

    A first-stage nozzle vane includes an airfoil having a profile according to Table I. The annulus profile of the hot gas path is defined in conjunction with the airfoil profile and the profile of the inner and outer walls by the Cartesian coordinate values given in Tables I and II, respectively. The airfoil is a three-dimensional bowed design, both in the airfoil body and in the trailing edge. The airfoil is steam and air-cooled by flowing cooling mediums through cavities extending in the vane between inner and outer walls.

  10. Hook nozzle arrangement for supporting airfoil vanes

    Science.gov (United States)

    Shaffer, James E.; Norton, Paul F.

    1996-01-01

    A gas turbine engine's nozzle structure includes a nozzle support ring, a plurality of shroud segments, and a plurality of airfoil vanes. The plurality of shroud segments are distributed around the nozzle support ring. Each airfoil vane is connected to a corresponding shroud segment so that the airfoil vanes are also distributed around the nozzle support ring. Each shroud segment has a hook engaging the nozzle support ring so that the shroud segments and corresponding airfoil vanes are supported by the nozzle support ring. The nozzle support ring, the shroud segments, and the airfoil vanes may be ceramic.

  11. Airfoil characteristics for wind turbines

    DEFF Research Database (Denmark)

    Bak, C.; Fuglsang, P.; Sørensen, Niels N.;

    1999-01-01

    the tip is low and that it is high at the root compared to 2D airfoil characteristics. The use of these characteristics in aeroelastic calculations shows agood agreement in power and flap moments with measurements. Furthermore, a fatigue analysis shows a reduction in the loads of up to 15 % compared...... to a commonly used set of airfoil characteristics. The numerical optimisation is based on both the 3D CFDcomputations and measurements on a 41-m rotor with LM 19.1 and LM 19.0 blades, respectively. The method requires power and loads from a turbine and is promising since a set of lift and drag curves...

  12. Airfoil model in Two-Dimensional Low-Turbulence Tunnel

    Science.gov (United States)

    1939-01-01

    Airfoil model with pressure taps inside the test section of the Two-Dimensional Low-Turbulence Tunnel. The Two-Dimensional Low-Turbulence Tunnel was originally called the Refrigeration or 'Ice' tunnel because it was intended to support research on aircraft icing. The tunnel was built of wood, lined with sheet steel, and heavily insulated on the outside. Refrigeration equipment was installed to generate icing conditions inside the test section. The NACA sent out a questionnaire to airline operators, asking them to detail the specific kinds of icing problems they encountered in flight. The replies became the basis for a comprehensive research program begun in 1938 when the tunnel commenced operation. Research quickly focused on the concept of using exhaust heat to prevent ice from forming on the wing's leading edge. This project was led by Lewis Rodert, who later would win the Collier Trophy for his work on deicing. By 1940, aircraft icing research had shifted to the new Ames Research Laboratory, and the Ice tunnel was refitted with screens and honeycomb. Researchers were trying to eliminate all turbulence in the test section. From TN 1283: 'The Langley two-dimensional low-turbulence pressure tunnel is a single-return closed-throat tunnel.... The tunnel is constructed of heavy steel plate so that the pressure of the air may be varied from approximately full vacuum to 10 atmospheres absolute, thereby giving a wide range of air densities. Reciprocating compressors with a capacity of 1200 cubic feet of free air per minute provide compressed air. Since the tunnel shell has a volume of about 83,000 cubic feet, a compression rate of approximately one atmosphere per hour is obtained. ... The test section is rectangular in shape, 3 feet wide, 7 1/2 feet high, and 7 1/2 feet long. ... The over-all size of the wind-tunnel shell is about 146 feet long and 58 feet wide with a maximum diameter of 26 feet. The test section and entrance and exit cones are surrounded by a 22-foot

  13. Hybrid airfoil design methods for full-scale ice accretion simulation

    Science.gov (United States)

    Saeed, Farooq

    The objective of this thesis is to develop a design method together with a design philosophy that allows the design of "subscale" or "hybrid" airfoils that simulate fullscale ice accretions. These subscale or hybrid airfoils have full-scale leading edges and redesigned aft-sections. A preliminary study to help develop a design philosophy for the design of hybrid airfoils showed that hybrid airfoils could be designed to simulate full-scale airfoil droplet-impingement characteristics and, therefore, ice accretion. The study showed that the primary objective in such a design should be to determine the aft section profile that provides the circulation necessary for simulating full-scale airfoil droplet-impingement characteristics. The outcome of the study, therefore, reveals circulation control as the main design variable. To best utilize this fact, this thesis describes two innovative airfoil design methods for the design of hybrid airfoils. Of the two design methods, one uses a conventional flap system while the other only suggests the use of boundary-layer control through slot-suction on the airfoil upper surface as a possible alternative for circulation control. The formulation of each of the two design methods is described in detail, and the results from each method are validated using wind-tunnel test data. The thesis demonstrates the capabilities of each method with the help of specific design examples highlighting their application potential. In particular, the flap-system based hybrid airfoil design method is used to demonstrate the design of a half-scale hybrid model of a full-scale airfoil that simulates full-scale ice accretion at both the design and off-design conditions. The full-scale airfoil used is representative of a scaled modern business-jet main wing section. The study suggests some useful advantages of using hybrid airfoils as opposed to full-scale airfoils for a better understanding of the ice accretion process and the related issues. Results

  14. A two element laminar flow airfoil optimized for cruise. M.S. Thesis

    Science.gov (United States)

    Steen, Gregory Glen

    1994-01-01

    Numerical and experimental results are presented for a new two-element, fixed-geometry natural laminar flow airfoil optimized for cruise Reynolds numbers on the order of three million. The airfoil design consists of a primary element and an independent secondary element with a primary to secondary chord ratio of three to one. The airfoil was designed to improve the cruise lift-to-drag ratio while maintaining an appropriate landing capability when compared to conventional airfoils. The airfoil was numerically developed utilizing the NASA Langley Multi-Component Airfoil Analysis computer code running on a personal computer. Numerical results show a nearly 11.75 percent decrease in overall wing drag with no increase in stall speed at sailplane cruise conditions when compared to a wing based on an efficient single element airfoil. Section surface pressure, wake survey, transition location, and flow visualization results were obtained in the Texas A&M University Low Speed Wind Tunnel. Comparisons between the numerical and experimental data, the effects of the relative position and angle of the two elements, and Reynolds number variations from 8 x 10(exp 5) to 3 x 10(exp 6) for the optimum geometry case are presented.

  15. OUT Success Stories: Advanced Airfoils for Wind Turbines

    Science.gov (United States)

    Jones, J.; Green, B.

    2000-08-01

    New airfoils have substantially increased the aerodynamic efficiency of wind turbines. It is clear that these new airfoils substantially increased energy output from wind turbines. Virtually all new blades built in this country today use these advanced airfoil designs.

  16. Adjoint-based airfoil shape optimization in transonic flow

    Science.gov (United States)

    Gramanzini, Joe-Ray

    The primary focus of this work is efficient aerodynamic shape optimization in transonic flow. Adjoint-based optimization techniques are employed on airfoil sections and evaluated in terms of computational accuracy as well as efficiency. This study examines two test cases proposed by the AIAA Aerodynamic Design Optimization Discussion Group. The first is a two-dimensional, transonic, inviscid, non-lifting optimization of a Modified-NACA 0012 airfoil. The second is a two-dimensional, transonic, viscous optimization problem using a RAE 2822 airfoil. The FUN3D CFD code of NASA Langley Research Center is used as the ow solver for the gradient-based optimization cases. Two shape parameterization techniques are employed to study their effect and the number of design variables on the final optimized shape: Multidisciplinary Aerodynamic-Structural Shape Optimization Using Deformation (MASSOUD) and the BandAids free-form deformation technique. For the two airfoil cases, angle of attack is treated as a global design variable. The thickness and camber distributions are the local design variables for MASSOUD, and selected airfoil surface grid points are the local design variables for BandAids. Using the MASSOUD technique, a drag reduction of 72.14% is achieved for the NACA 0012 case, reducing the total number of drag counts from 473.91 to 130.59. Employing the BandAids technique yields a 78.67% drag reduction, from 473.91 to 99.98. The RAE 2822 case exhibited a drag reduction from 217.79 to 132.79 counts, a 39.05% decrease using BandAids.

  17. Airfoil seal system for gas turbine engine

    Science.gov (United States)

    Diakunchak, Ihor S.

    2013-06-25

    A turbine airfoil seal system of a turbine engine having a seal base with a plurality of seal strips extending therefrom for sealing gaps between rotational airfoils and adjacent stationary components. The seal strips may overlap each other and may be generally aligned with each other. The seal strips may flex during operation to further reduce the gap between the rotational airfoils and adjacent stationary components.

  18. Prediction of the Effect of Vortex Generators on Airfoil Performance

    International Nuclear Information System (INIS)

    Vortex Generators (VGs) are widely used by the wind turbine industry, to control the flow over blade sections. The present work describes a computational fluid dynamic procedure that can handle a geometrical resolved VG on an airfoil section. After describing the method, it is applied to two different airfoils at a Reynolds number of 3 million, the FFA- W3-301 and FFA-W3-360, respectively. The computations are compared with wind tunnel measurements from the Stuttgart Laminar Wind Tunnel with respect to lift and drag variation as function of angle of attack. Even though the method does not exactly capture the measured performance, it can be used to compare different VG setups qualitatively with respect to chord- wise position, inter and intra-spacing and inclination of the VGs already in the design phase

  19. Wavy flow cooling concept for turbine airfoils

    Science.gov (United States)

    Liang, George

    2010-08-31

    An airfoil including an outer wall and a cooling cavity formed therein. The cooling cavity includes a leading edge flow channel located adjacent a leading edge of the airfoil and a trailing edge flow channel located adjacent a trailing edge of the airfoil. Each of the leading edge and trailing edge flow channels define respective first and second flow axes located between pressure and suction sides of the airfoil. A plurality of rib members are located within each of the flow channels, spaced along the flow axes, and alternately extending from opposing sides of the flow channels to define undulating flow paths through the flow channels.

  20. Generalized multi-point inverse airfoil design

    Science.gov (United States)

    Selig, Michael S.; Maughmer, Mark D.

    1991-01-01

    In a rather general sense, inverse airfoil design can be taken to mean the problem of specifying a desired set of airfoil characteristics, such as the airfoil maximum thickness ratio, pitching moment, part of the velocity distribution or boundary-layer development, etc., then from this information determine the corresponding airfoil shape. This paper presents a method which approaches the design problem from this perspective. In particular, the airfoil is divided into segments along which, together with the design conditions, either the velocity distribution or boundary-layer development may be prescribed. In addition to these local desired distributions, single parameters like the airfoil thickness can be specified. The problem of finding the airfoil shape is determined by coupling an incompressible, inviscid, inverse airfoil design method with a direct integral boundary-layer analysis method and solving the resulting nonlinear equations via a multidimensional Newton iteration technique. The approach is fast and easily allows for interactive design. It is also flexible and could be adapted to solving compressible, inverse airfoil design problems.

  1. 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

  2. On the acoustic signature of tandem airfoils: The sound of an elastic airfoil in the wake of a vortex generator

    Science.gov (United States)

    Manela, A.

    2016-07-01

    The acoustic signature of an acoustically compact tandem airfoil setup in uniform high-Reynolds number flow is investigated. The upstream airfoil is considered rigid and is actuated at its leading edge with small-amplitude harmonic pitching motion. The downstream airfoil is taken passive and elastic, with its motion forced by the vortex-street excitation of the upstream airfoil. The non-linear near-field description is obtained via potential thin-airfoil theory. It is then applied as a source term into the Powell-Howe acoustic analogy to yield the far-field dipole radiation of the system. To assess the effect of downstream-airfoil elasticity, results are compared with counterpart calculations for a non-elastic setup, where the downstream airfoil is rigid and stationary. Depending on the separation distance between airfoils, airfoil-motion and airfoil-wake dynamics shift between in-phase (synchronized) and counter-phase behaviors. Consequently, downstream airfoil elasticity may act to amplify or suppress sound through the direct contribution of elastic-airfoil motion to the total signal. Resonance-type motion of the elastic airfoil is found when the upstream airfoil is actuated at the least stable eigenfrequency of the downstream structure. This, again, results in system sound amplification or suppression, depending on the separation distance between airfoils. With increasing actuation frequency, the acoustic signal becomes dominated by the direct contribution of the upstream airfoil motion, whereas the relative contribution of the elastic airfoil to the total signature turns negligible.

  3. Measuring Lift with the Wright Airfoils

    Science.gov (United States)

    Heavers, Richard M.; Soleymanloo, Arianne

    2011-01-01

    In this laboratory or demonstration exercise, we mount a small airfoil with its long axis vertical at one end of a nearly frictionless rotating platform. Air from a leaf blower produces a sidewise lift force L on the airfoil and a drag force D in the direction of the air flow (Fig. 1). The rotating platform is kept in equilibrium by adding weights…

  4. Leading edge embedded fan airfoil concept -- A new powered high lift technology

    Science.gov (United States)

    Phan, Nhan Huu

    A new powered-lift airfoil concept called Leading Edge Embedded Fan (LEEF) is proposed for Extremely Short Take-Off and Landing (ESTOL) and Vertical Take-Off and Landing (VTOL) applications. The LEEF airfoil concept is a powered-lift airfoil concept capable of generating thrust and very high lift-coefficient at extreme angles-of attack (AoA). It is designed to activate only at the take-off and landing phases, similar to conventional flaps or slats, allowing the aircraft to operate efficiently at cruise in its conventional configuration. The LEEF concept consists of placing a crossflow fan (CFF) along the leading-edge (LE) of the wing, and the housing is designed to alter the airfoil shape between take-off/landing and cruise configurations with ease. The unique rectangular cross section of the crossflow fan allows for its ease of integration into a conventional subsonic wing. This technology is developed for ESTOL aircraft applications and is most effectively applied to General Aviation (GA) aircraft. Another potential area of application for LEEF is tiltrotor aircraft. Unlike existing powered high-lift systems, the LEEF airfoil uses a local high-pressure air source from cross-flow fans, does not require ducting, and is able to be deployed using distributed electric power systems throughout the wing. In addition to distributed lift augmentation, the LEEF system can provide additional thrust during takeoff and landing operation to supplement the primary cruise propulsion system. Two-dimensional (2D) and three-dimensional (3D) Computational Fluid Dynamics (CFD) simulations of a conventional airfoil/wing using the NACA 63-3-418 section, commonly used in GA, and a LEEF airfoil/wing embedded into the same airfoil section were carried out to evaluate the advantages of and the costs associated with implementing the LEEF concept. Computational results show that significant lift and augmented thrust are available during LEEF operation while requiring only moderate fan power

  5. Experimental Evaluation of Aerodynamics Characteristics of a Baseline Airfoil

    Directory of Open Access Journals (Sweden)

    Md. Rasedul Islam

    2015-01-01

    Full Text Available A wind tunnel test of baseline airfoil NACA 0015 model was conducted in the Wind tunnel wall test section of the Department of Mechanical Engineering at KUET, Bangladesh . The primary goal of the test was to measure airfoil aerodynamic characteristics over a wide range of Angle of Attack (AOA mainly from Zero degree to 20 degree AOA and with a wind tunnel fixed free stream velocity of 12m/s and at Re = 1.89×105 . The pressure distribution in both upper and lower camber surface was calculated with the help of digital pressure manometer. After analysis the value of Cl and Cd was found around 1.3 and 0.31 respectively.

  6. 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.

  7. Hybrid Optimization for Wind Turbine Thick Airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Grasso, F. [ECN Wind Energy, Petten (Netherlands)

    2012-06-15

    One important element in aerodynamic design of wind turbines is the use of specially tailored airfoils to increase the ratio of energy capture and reduce cost of energy. This work is focused on the design of thick airfoils for wind turbines by using numerical optimization. A hybrid scheme is proposed in which genetic and gradient based algorithms are combined together to improve the accuracy and the reliability of the design. Firstly, the requirements and the constraints for this class of airfoils are described; then, the hybrid approach is presented. The final part of this work is dedicated to illustrate a numerical example regarding the design of a new thick airfoil. The results are discussed and compared to existing airfoils.

  8. 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....

  9. Personal and trip characteristics associated with safety equipment use by injured adult bicyclists: a cross-sectional study

    Directory of Open Access Journals (Sweden)

    Teschke Kay

    2012-09-01

    Full Text Available Abstract Background The aim of this study was to estimate use of helmets, lights, and visible clothing among cyclists and to examine trip and personal characteristics associated with their use. Methods Using data from a study of transportation infrastructure and injuries to 690 adult cyclists in Toronto and Vancouver, Canada, we examined the proportion who used bike lights, conspicuous clothing on the torso, and helmets on their injury trip. Multiple logistic regression was used to examine associations between personal and trip characteristics and each type of safety equipment. Results Bike lights were the least frequently used (20% of all trips although they were used on 77% of trips at night. Conspicuous clothing (white, yellow, orange, red was worn on 33% of trips. Helmets were used on 69% of trips, 76% in Vancouver where adult helmet use is required by law and 59% in Toronto where it is not. Factors positively associated with bike light use included night, dawn and dusk trips, poor weather conditions, weekday trips, male sex, and helmet use. Factors positively associated with conspicuous clothing use included good weather conditions, older age, and more frequent cycling. Factors positively associated with helmet use included bike light use, longer trip distances, hybrid bike type, not using alcohol in the 6 hours prior to the trip, female sex, older age, higher income, and higher education. Conclusions In two of Canada’s largest cities, helmets were the most widely used safety equipment. Measures to increase use of visibility aids on both daytime and night-time cycling trips may help prevent crashes.

  10. Study of a new airfoil used in reversible axial fans

    Science.gov (United States)

    Li, Chaojun; Wei, Baosuo; Gu, Chuangang

    1991-01-01

    The characteristics of the reverse ventilation of axial flow are analyzed. An s shaped airfoil with a double circular arc was tested in a wind tunnel. The experimental results showed that the characteristics of this new airfoil in reverse ventilation are the same as those in normal ventilation, and that this airfoil is better than the existing airfoils used on reversible axial fans.

  11. Aerodynamics Investigation of Faceted Airfoils at Low Reynolds Number

    Science.gov (United States)

    Napolillo, Zachary G.

    The desire and demand to fly farther and faster has progressively integrated the concept of optimization with airfoil design, resulting in increasingly complex numerical tools pursuing efficiency often at diminishing returns; while the costs and difficulty associated with fabrication increases with design complexity. Such efficiencies may often be necessary due to the power density limitations of certain aircraft such as small unmanned aerial vehicles (UAVs) and micro air vehicles (MAVs). This research, however, focuses on reducing the complexity of airfoils for applications where aerodynamic performance is less important than the efficiency of manufacturing; in this case a Hybrid Projectile. By employing faceted sections to approximate traditional contoured wing sections it may be possible to expedite manufacturing and reduce costs. We applied this method to the development of a low Reynolds number, disposable Hybrid Projectile requiring a 4.5:1 glide ratio, resulting in a series of airfoils which are geometric approximations to highly contoured cross-sections called ShopFoils. This series of airfoils both numerically and experimentally perform within a 10% margin of the SD6060 airfoil at low Re. Additionally, flow visualization has been conducted to qualitatively determine what mechanisms, if any, are responsible for the similarity in performance between the faceted ShopFoil sections and the SD6060. The data obtained by these experiments did not conclusively reveal how the faceted surfaces may influence low Re flow but did indicate that the ShopFoil s did not maintain flow attachment at higher angles of attack than the SD6060. Two reasons are provided for the unexpected performance of the ShopFoil: one is related to downwash effects, which are suspected of placing the outer portion of the span at an effective angle of attack where the ShopFoils outperform the SD6060; the other is the influence of the tip vortex on separation near the wing tips, which possibly

  12. Spline-Based Smoothing of Airfoil Curvatures

    Science.gov (United States)

    Li, W.; Krist, S.

    2008-01-01

    Constrained fitting for airfoil curvature smoothing (CFACS) is a splinebased method of interpolating airfoil surface coordinates (and, concomitantly, airfoil thicknesses) between specified discrete design points so as to obtain smoothing of surface-curvature profiles in addition to basic smoothing of surfaces. CFACS was developed in recognition of the fact that the performance of a transonic airfoil is directly related to both the curvature profile and the smoothness of the airfoil surface. Older methods of interpolation of airfoil surfaces involve various compromises between smoothing of surfaces and exact fitting of surfaces to specified discrete design points. While some of the older methods take curvature profiles into account, they nevertheless sometimes yield unfavorable results, including curvature oscillations near end points and substantial deviations from desired leading-edge shapes. In CFACS as in most of the older methods, one seeks a compromise between smoothing and exact fitting. Unlike in the older methods, the airfoil surface is modified as little as possible from its original specified form and, instead, is smoothed in such a way that the curvature profile becomes a smooth fit of the curvature profile of the original airfoil specification. CFACS involves a combination of rigorous mathematical modeling and knowledge-based heuristics. Rigorous mathematical formulation provides assurance of removal of undesirable curvature oscillations with minimum modification of the airfoil geometry. Knowledge-based heuristics bridge the gap between theory and designers best practices. In CFACS, one of the measures of the deviation of an airfoil surface from smoothness is the sum of squares of the jumps in the third derivatives of a cubicspline interpolation of the airfoil data. This measure is incorporated into a formulation for minimizing an overall deviation- from-smoothness measure of the airfoil data within a specified fitting error tolerance. CFACS has been

  13. Nonlinear aeroelastic behavior of compliant airfoils

    International Nuclear Information System (INIS)

    Since the beginning of aviation and up to the present time, airfoils have always been built as rigid structures. They are designed to fly under their divergence speed in order to avoid static aeroelastic instabilities and the resulting large deformations, which are not compatible with the typically low compliance of such airfoils. In recent years, research on airfoil morphing has generated interest in innovative ideas like the use of compliant systems, i.e. systems built to allow for large deformations without failure, in airfoil construction. Such systems can operate in the neighborhood of divergence and take advantage of large aeroelastic servo-effects. This, in turn, allows compact, advanced actuators to control the airfoil's deformation and loads, and hence complement or even replace conventional flaps. In order to analyze and design such compliant, active aeroelastic structures a nonlinear approach to static aeroelasticity is needed, which takes into account the effect of large deformations on aerodynamics and structure. Such an analytical approach is presented in this paper and applied to a compliant passive airfoil as the preliminary step in the realization of a piezoelectrically driven, active aeroelastic airfoil. Wind tunnel test results are also presented and compared with the analytic prediction. The good agreement and the observed behavior in the wind tunnel give confidence in the potential of this innovative idea

  14. 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.

  15. Design of a new urban wind turbine airfoil using a pressure-load inverse method

    Energy Technology Data Exchange (ETDEWEB)

    Henriques, J.C.C.; Gato, L.M.C. [IDMEC, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Marques da Silva, F. [LNEC - Laboratorio Nacional de Engenharia Civil, Av. Brasil, 101, 1700-066 Lisboa (Portugal); Estanqueiro, A.I. [INETI - Instituto Nacional de Engenharia, Tecnologia e Inovacao Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal)

    2009-12-15

    This paper presents the design methodology of a new wind turbine airfoil that achieves high performance in urban environment by increasing the maximum lift. For this purpose, an inverse method was applied to obtain a new wind turbine blade section with constant pressure-load along the chord, at the design inlet angle. In comparison with conventional blade section designs, the new airfoil has increased maximum lift, reduced leading edge suction peak and controlled soft-stall behaviour, due to a reduction of the adverse pressure gradient on the suction side. Wind tunnel experimental results confirmed the computational results. (author)

  16. Airfoil profile drag increase due to acoustic excitation

    Science.gov (United States)

    Shearin, John G.; Jones, Michael G.

    1989-04-01

    A two-dimensional airfoil (NACA-0009) is subjected to high intensity pure-tone sound over a 1-5 kHz frequency range while immersed in a flow with 240 ft/sec velocity in a quiet flow facility with a Reynolds number of 3 million. Wake dynamic pressures are determined, and the momentum deficit is used to calculate a two-dimensional drag coefficient. Significant increases in drag are observed when the airfoil is subjected to high-intensity sound at critical frequencies. The increased drag is accompanied by movement of the natural transition location. When the transition is fixed by roughness at 10 percent chord, no further transition movement is observed in response to an acoustic Tollmien-Schlichting disturbance. However, a 4 percent increase in the sectional drag coefficient is noted. It is believed to be due to the sound exciting the flow near the airfoil surface (shear layer), thus causing the existing turbulence to become more intense, possess a higher mixing rate (momentum), and increase the skin friction.

  17. Inviscid double wake model for stalled airfoils

    DEFF Research Database (Denmark)

    Marion, Lucas; Ramos García, Néstor; Sørensen, Jens Nørkær

    2014-01-01

    An inviscid double wake model based on a steady two-dimensional panel method has been developed to predict aerodynamic loads of wind turbine airfoils in the deep stall region. The separated flow is modelled using two constant vorticity sheets which are released at the trailing edge and at the...... separation point. A calibration of the code through comparison with experiments has been performed using one set of airfoils. A second set of airfoils has been used for the validation of the calibrated model. Predicted aerodynamic forces for a wide range of angles of attack (0 to 90 deg) are in overall good...

  18. Turbine airfoil with outer wall thickness indicators

    Science.gov (United States)

    Marra, John J; James, Allister W; Merrill, Gary B

    2013-08-06

    A turbine airfoil usable in a turbine engine and including a depth indicator for determining outer wall blade thickness. The airfoil may include an outer wall having a plurality of grooves in the outer surface of the outer wall. The grooves may have a depth that represents a desired outer surface and wall thickness of the outer wall. The material forming an outer surface of the outer wall may be removed to be flush with an innermost point in each groove, thereby reducing the wall thickness and increasing efficiency. The plurality of grooves may be positioned in a radially outer region of the airfoil proximate to the tip.

  19. Turbine airfoil to shroud attachment method

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Christian X; Kulkarni, Anand A; James, Allister W; Wessell, Brian J; Gear, Paul J

    2014-12-23

    Bi-casting a platform (50) onto an end portion (42) of a turbine airfoil (31) after forming a coating of a fugitive material (56) on the end portion. After bi-casting the platform, the coating is dissolved and removed to relieve differential thermal shrinkage stress between the airfoil and platform. The thickness of the coating is varied around the end portion in proportion to varying amounts of local differential process shrinkage. The coating may be sprayed (76A, 76B) onto the end portion in opposite directions parallel to a chord line (41) of the airfoil or parallel to a mid-platform length (80) of the platform to form respective layers tapering in thickness from the leading (32) and trailing (34) edges along the suction side (36) of the airfoil.

  20. Airfoil for a gas turbine

    Science.gov (United States)

    Liang, George

    2011-01-18

    An airfoil is provided for a gas turbine comprising an outer structure comprising a first wall, an inner structure comprising a second wall spaced relative to the first wall such that a cooling gap is defined between at least portions of the first and second walls, and seal structure provided within the cooling gap between the first and second walls for separating the cooling gap into first and second cooling fluid impingement gaps. An inner surface of the second wall may define an inner cavity. The inner structure may further comprise a separating member for separating the inner cavity of the inner structure into a cooling fluid supply cavity and a cooling fluid collector cavity. The second wall may comprise at least one first impingement passage, at least one second impingement passage, and at least one bleed passage.

  1. Modeling and Grid Generation of Iced Airfoils

    Science.gov (United States)

    Vickerman, Mary B.; Baez, Marivell; Braun, Donald C.; Hackenberg, Anthony W.; Pennline, James A.; Schilling, Herbert W.

    2007-01-01

    SmaggIce Version 2.0 is a software toolkit for geometric modeling and grid generation for two-dimensional, singleand multi-element, clean and iced airfoils. A previous version of SmaggIce was described in Preparing and Analyzing Iced Airfoils, NASA Tech Briefs, Vol. 28, No. 8 (August 2004), page 32. To recapitulate: Ice shapes make it difficult to generate quality grids around airfoils, yet these grids are essential for predicting ice-induced complex flow. This software efficiently creates high-quality structured grids with tools that are uniquely tailored for various ice shapes. SmaggIce Version 2.0 significantly enhances the previous version primarily by adding the capability to generate grids for multi-element airfoils. This version of the software is an important step in streamlining the aeronautical analysis of ice airfoils using computational fluid dynamics (CFD) tools. The user may prepare the ice shape, define the flow domain, decompose it into blocks, generate grids, modify/divide/merge blocks, and control grid density and smoothness. All these steps may be performed efficiently even for the difficult glaze and rime ice shapes. Providing the means to generate highly controlled grids near rough ice, the software includes the creation of a wrap-around block (called the "viscous sublayer block"), which is a thin, C-type block around the wake line and iced airfoil. For multi-element airfoils, the software makes use of grids that wrap around and fill in the areas between the viscous sub-layer blocks for all elements that make up the airfoil. A scripting feature records the history of interactive steps, which can be edited and replayed later to produce other grids. Using this version of SmaggIce, ice shape handling and grid generation can become a practical engineering process, rather than a laborious research effort.

  2. Computational investigation of subsonic torsional airfoil flutter

    OpenAIRE

    Kakkavas, Constantinos

    1998-01-01

    In this thesis single-degree-of-freedom torsional airfoil flutter is investigated using an incompressible potential flow code, a compressible inviscid Euler code and a compressible viscous Navier-Stokes code. It is found that the classical linearized incompressible and compressible flow theories yield unconservative flutter estimates. The computations based on the non-linear codes show for NACA 0006, NACA 0009, NACA 0012 and NACA 0015 airfoils, that the regions of torsional flutter instabilit...

  3. Flow past a self-oscillating airfoil with two degrees of freedom: measurements and simulations

    Directory of Open Access Journals (Sweden)

    Šidlof Petr

    2014-03-01

    Full Text Available The paper focuses on investigation of the unsteady subsonic airflow past an elastically supported airfoil for subcritical flow velocities and during the onset of the flutter instability. A physical model of the NACA0015 airfoil has been designed and manufactured, allowing motion with two degrees of freedom: pitching (rotation about the elastic axis and plunging (vertical motion. The structural mass and stiffness matrix can be tuned to certain extent, so that the natural frequencies of the two modes approach as needed. The model was placed in the measuring section of the wind tunnel in the aerodynamic laboratory of the Institute of Thermomechanics in Nový Knín, and subjected to low Mach number airflow up to the flow velocities when self-oscillation reach amplitudes dangerous for the structural integrity of the model. The motion of the airfoil was registered by a high-speed camera, with synchronous measurement of the mechanic vibration and discrete pressure sensors on the surface of the airfoil. The results of the measurements are presented together with numerical simulation results, based on a finite volume CFD model of airflow past a vibrating airfoil.

  4. Flow past a self-oscillating airfoil with two degrees of freedom: measurements and simulations

    Science.gov (United States)

    Šidlof, Petr; Štěpán, Martin; Vlček, Václav; Řidký, Václav; Šimurda, David; Horáček, Jaromír

    2014-03-01

    The paper focuses on investigation of the unsteady subsonic airflow past an elastically supported airfoil for subcritical flow velocities and during the onset of the flutter instability. A physical model of the NACA0015 airfoil has been designed and manufactured, allowing motion with two degrees of freedom: pitching (rotation about the elastic axis) and plunging (vertical motion). The structural mass and stiffness matrix can be tuned to certain extent, so that the natural frequencies of the two modes approach as needed. The model was placed in the measuring section of the wind tunnel in the aerodynamic laboratory of the Institute of Thermomechanics in Nový Knín, and subjected to low Mach number airflow up to the flow velocities when self-oscillation reach amplitudes dangerous for the structural integrity of the model. The motion of the airfoil was registered by a high-speed camera, with synchronous measurement of the mechanic vibration and discrete pressure sensors on the surface of the airfoil. The results of the measurements are presented together with numerical simulation results, based on a finite volume CFD model of airflow past a vibrating airfoil.

  5. LDV measurements of the velocity field on the inlet section of a pumped storage equipped with a symmetrical suction elbow for variable discharge values

    International Nuclear Information System (INIS)

    The storage pumps are equipped with various types of inlet casings. The flow nonuniformity is generated by the suction elbows being ingested by the impeller leading to unsteady phenomena and worse cavitational behaviour. A symmetrical suction elbow model corresponding to the double flux storage pump was manufactured and installed on the test rig in order to assess the flow field at the pump inlet. The experimental investigations are performed for 9 discharge values from 0.5 to 1.3 of nominal discharge. LDV measurements are performed on the annular section of the pump inlet in order to quantify the flow non-uniformity generated by the symmetrical suction elbow. Both axial and circumferential velocity components are simultaneously measured on the half plane (180°) of the annular inlet section along to 19 survey axis with 62 points on each. The flow field on the next half plane is determined tacking into account the symmetry. As a result, the flow map on the pump inlet annular section is reconstructed revealing a significant variation of the circumferential velocity component. The absolute flow angle is computed showing a significant variation of ±38°

  6. LDV measurements of the velocity field on the inlet section of a pumped storage equipped with a symmetrical suction elbow for variable discharge values

    Science.gov (United States)

    ǎghici, I., Dr; Muntean, S.; Bosioc, A. I.; Anton, L. E.

    2014-03-01

    The storage pumps are equipped with various types of inlet casings. The flow nonuniformity is generated by the suction elbows being ingested by the impeller leading to unsteady phenomena and worse cavitational behaviour. A symmetrical suction elbow model corresponding to the double flux storage pump was manufactured and installed on the test rig in order to assess the flow field at the pump inlet. The experimental investigations are performed for 9 discharge values from 0.5 to 1.3 of nominal discharge. LDV measurements are performed on the annular section of the pump inlet in order to quantify the flow non-uniformity generated by the symmetrical suction elbow. Both axial and circumferential velocity components are simultaneously measured on the half plane (180°) of the annular inlet section along to 19 survey axis with 62 points on each. The flow field on the next half plane is determined tacking into account the symmetry. As a result, the flow map on the pump inlet annular section is reconstructed revealing a significant variation of the circumferential velocity component. The absolute flow angle is computed showing a significant variation of ±38°.

  7. Intermittent Flow Regimes in a Transonic Fan Airfoil Cascade

    OpenAIRE

    2004-01-01

    A study was conducted in the NASA Glenn Research Center (NASA-GRC) linear cascade on the intermittent flow on the suction surface of an airfoil section from the tip region of a modern low aspect ratio fan blade. Experimental results revealed that, at a large incidence angle, a range of transonic inlet Mach numbers exist where the leading-edge shock-wave pattern was unstable. Flush-mounted, high-frequency response pressure transducers indicated large local jumps in the pressure in the leading ...

  8. Enhancement of Aerodynamic Properties of an Airfoil by Co Flow Jet (CFJ Flow

    Directory of Open Access Journals (Sweden)

    Md. Amzad Hossain

    2015-01-01

    Full Text Available A wind tunnel test of baseline airfoil NACA 0015 and CFJ0015-065-065 model was conducted in the Wind tunnel wall test section of the Department of Mechanical Engineering at KUET, Bangladesh. The primary goal of the test was to investigate and compare the airfoil aerodynamic characteristics over a wide range of Angle of Attack (AOA and with a wind tunnel free stream velocity of 12m/s , Re = 1.89×105, Cµ = 0.07 at M = 0.030 kg/s. The CFJ increases CL max by 82.5% and decreases Drag by 16.5% at Stall AOA when compared to the baseline air foil. The main goal is to proof that Flow separation is controlled and delayed with the use of CFJ Technique over an Airfoil.

  9. Probabilistic Design of Hollow Airfoil Composite Structure by Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Mr. Sachin M. Shinde

    2014-04-01

    Full Text Available This study represents simulation of Airfoil composite beam by using Monte Carlo method. A three dimensional static analysis of large displacement type has been carried out. Finite element analysis of NACA0012 airfoil composite structure has been carried out and uncertainty in bending stress is analyzed. Bending stress was objective function. Chord length , beam length ,elastic modulus in XY,YZ,XZ and shear modulus of epoxy graphite in XY,YZ,XZ, ply angle and ply thickness of airfoil section, force are varied within effective range and their effect on bending stress has been analyzed. In order to validate the results, one loop of simulation is benchmarked from results in literature. Ultimately, best set of probabilistic design variable is proposed to reduce bending stress under static loading condition.

  10. Adjoint Airfoil Optimization of Darrieus-Type Vertical Axis Wind Turbine

    Science.gov (United States)

    Fuchs, Roman; Nordborg, Henrik

    2012-11-01

    We present the feasibility of using an adjoint solver to optimize the torque of a Darrieus-type vertical axis wind turbine (VAWT). We start with a 2D cross section of a symmetrical airfoil and restrict us to low solidity ratios to minimize blade vortex interactions. The adjoint solver of the ANSYS FLUENT software package computes the sensitivities of airfoil surface forces based on a steady flow field. Hence, we find the torque of a full revolution using a weighted average of the sensitivities at different wind speeds and angles of attack. The weights are computed analytically, and the range of angles of attack is given by the tip speed ratio. Then the airfoil geometry is evolved, and the proposed methodology is evaluated by transient simulations.

  11. 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

    Silicon-based ceramics have been proposed as component materials for gas turbine engine hot-sections. When the Navy s Harrier fighter experienced engine (Pegasus F402) failure because of leading-edge durability problems on the second-stage high-pressure turbine vane, the Office of Naval Research came to the NASA Glenn Research Center at Lewis Field for test support in evaluating a concept for eliminating the vane-edge degradation. The High Pressure Burner Rig (HPBR) was selected for testing since it could provide temperature, pressure, velocity, and combustion gas compositions that closely simulate the engine environment. The study focused on equipping the stationary metal airfoil (Pegasus F402) with a ceramic matrix composite (CMC) leading-edge insert and evaluating the feasibility and benefits of such a configuration. The test exposed the component, with and without the CMC insert, to the harsh engine environment in an unloaded condition, with cooling to provide temperature relief to the metal blade underneath. The insert was made using an AlliedSignal Composites, Inc., enhanced HiNicalon (Nippon Carbon Co. LTD., Yokohama, Japan) fiber-reinforced silicon carbide composite (SiC/SiC CMC) material fabricated via chemical vapor infiltration. This insert was 45-mils thick and occupied a recessed area in the leading edge and shroud of the vane. It was designed to be free floating with an end cap design. The HPBR tests provided a comparative evaluation of the temperature response and leading-edge durability and included cycling the airfoils between simulated idle, lift, and cruise flight conditions. In addition, the airfoils were aircooled, uniquely instrumented, and exposed to the exact set of internal and external conditions, which included gas temperatures in excess of 1370 C (2500 F). In addition to documenting the temperature response of the metal vane for comparison with the CMC, a demonstration of improved leading-edge durability was a primary goal. First, the

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

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Xu, Haoran;

    2013-01-01

    some models before they can be used in a BEM code. In this article, the airfoil data for the MEXICO (Model EXperiments in Controlled cOnditions) rotor are extracted from CFD (Computational Fluid Dynamics) results. The azimuthally averaged velocity is used as the sectional velocity to define the angle...

  13. Wind tunnel tests of the NACA 63-415 and a modified NACA 63-415 airfoil

    Energy Technology Data Exchange (ETDEWEB)

    Bak, C.; Fuglsang, P.; Johansen, J.; Antoniou, I.

    2000-12-01

    This report contains 2D measurements of the NACA 63-415 and a NACA 63-415 airfoil with modified leading edge called NACA 63-415-Risoe-D. The aerodynamic properties were derived from pressure measurements on the airfoil surface and in the wake. The VELUX open jet wind tunnel was used having a background turbulence intensity of 1%, an inlet flow velocity of 40 m/s which resulted in a Reynolds number of 1.6Oe10{sup 6}. The airfoil sections had a chord of 0.600 m and 0.606 m for NACA 63-415 and NACA 63-415-Risoe-D, respectively. The span was 1.9 m and end plates were used to minimise 3D flow effects. The measurements comprised both static and dynamic inflow where dynamic inflow was obtained by pitching the airfoil in a harmonic motion. We tested the influence of leading edge roughness, stall strips and vortex generators. For smooth surface conditions the modified airfoil showed an increase in lift-drag ratio before stall at {alpha}=8 from 67 to 72. Furthermore, the maximum lift increased from 1.33 to 1.37 while the minimum drag was maintained. Double stall was observed on the NACA 63-415 airfoil, but not on the modified airfoil. This was reflected in the standard deviation of both lift and drag in stall which was significantly lower for the modified airfoil indicating smooth and stable stall conditions. No significant differences were observed for dynamic stall. Test on both airfoil sections with zigzag tape at the leading edge towards the pressure side showed that the insensitivity to roughness was improved significantly for the modified airfoil. However, if zigzag tape was mounted at the leading edge towards the suction side less improvement was observed. Mounting of stall strips at and near the leading edge showed that only if they were mounted at the very vicinity of the leading edge the airfoil characteristics were affected significantly. If the stall strips were mounted on the pressure side downstream of approximately 1 % chord length only little influence was

  14. AirfoilPrep.py Documentation: Release 0.1.0

    Energy Technology Data Exchange (ETDEWEB)

    Ning, S. A. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2013-09-01

    AirfoilPrep.py provides functionality to preprocess aerodynamic airfoil data. Essentially, the module is an object oriented version of the AirfoilPrep spreadsheet with additional functionality and is written in the Python language. It allows the user to read in two-dimensional aerodynamic airfoil data, apply three-dimensional rotation corrections for wind turbine applications, and extend the datato very large angles of attack. This document discusses installation, usage, and documentation of the module.

  15. Wind Tunnel Aerodynamic Characteristics of a Transport-type Airfoil in a Simulated Heavy Rain Environment

    Science.gov (United States)

    Bezos, Gaudy M.; Dunham, R. Earl, Jr.; Gentry, Garl L., Jr.; Melson, W. Edward, Jr.

    1992-01-01

    The effects of simulated heavy rain on the aerodynamic characteristics of an NACA 64-210 airfoil section equipped with leading-and trailing-edge high-lift devices were investigated in the Langley 14- by 22-Foot Subsonic Tunnel. The model had a chord of 2.5 ft, a span of 8 ft, and was mounted on the tunnel centerline between two large endplates. Aerodynamic measurements in and out of the simulated rain environment were obtained for dynamic pressures of 30 and 50 psf and an angle-of-attack range of 0 to 20 degrees for the cruise configuration. The rain intensity was varied to produce liquid water contents ranging from 16 to 46 gm/cu m. The results obtained for various rain intensity levels and tunnel speeds showed significant losses in maximum lift capability and increases in drag for a given lift as the liquid water content was increased. The results obtained on the landing configuration also indicate a progressive decrease in the angle of attack at which maximum lift occurred and an increase in the slope of the pitching-moment curve as the liquid water content was increased. The sensitivity of test results to the effects of the water surface tension was also investigated. A chemical was introduced into the rain environment that reduced the surface tension of water by a factor of 2. The reduction in the surface tension of water did not significantly alter the level of performance losses for the landing configuration.

  16. Analysis of non-symmetrical flapping airfoils

    Institute of Scientific and Technical Information of China (English)

    W.B.Tay; K.B.Lim

    2009-01-01

    Simulations have been done to assess the lift, thrust and propulsive efficiency of different types of nonsymmetrical airfoils under different flapping configurations. The variables involved are reduced frequency, Strouhal number, pitch amplitude and phase angle. In order to analyze the variables more efficiently, the design of experiments using the response surface methodology is applied. Results show that both the variables and shape of the airfoil have a profound effect on the lift, thrust, and efficiency. By using nonsymmetrical airfoils, average lift coefficient as high as 2.23 can be obtained. The average thrust coefficient and efficiency also reach high values of 2.53 and 0.6 I, respectively. The lift production is highly dependent on the airfoil's shape while thrust production is influenced more heavily by the variables. Efficiency falls somewhere in between. Two-factor interactions are found to exist among the variables. This shows that it is not sufficient to analyze each variable individually. Vorticity diagrams are analyzed to explain the results obtained. Overall, the S1020 airfoil is able to provide relatively good efficiency and at the same time generate high thrust and lift force. These results aid in the design of a better omithopter's wing.

  17. 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....

  18. Comparative Study of Airfoil Flow Separation Criteria

    Science.gov (United States)

    Laws, Nick; Kahouli, Waad; Epps, Brenden

    2015-11-01

    Airfoil flow separation impacts a multitude of applications including turbomachinery, wind turbines, and bio-inspired micro-aerial vehicles. In order to achieve maximum performance, some devices operate near the edge of flow separation, and others use dynamic flow separation advantageously. Numerous criteria exist for predicting the onset of airfoil flow separation. This talk presents a comparative study of a number of such criteria, with emphasis paid to speed and accuracy of the calculations. We evaluate the criteria using a two-dimensional unsteady vortex lattice method, which allows for rapid analysis (on the order of seconds instead of days for a full Navier-Stokes solution) and design of optimal airfoil geometry and kinematics. Furthermore, dynamic analyses permit evaluation of dynamic stall conditions for enhanced lift via leading edge vortex shedding, commonly present in small flapping-wing flyers such as the bumblebee and hummingbird.

  19. Turbine airfoil fabricated from tapered extrusions

    Science.gov (United States)

    Marra, John J

    2013-07-16

    An airfoil (30) and fabrication process for turbine blades with cooling channels (26). Tapered tubes (32A-32D) are bonded together in a parallel sequence, forming a leading edge (21), a trailing edge (22), and pressure and suction side walls (23, 24) connected by internal ribs (25). The tapered tubes may be extruded without camber to simplify the extrusion process, then bonded along matching surfaces (34), forming a non-cambered airfoil (28), which may be cambered in a hot forming process and cut (48) to length. The tubes may have tapered walls that are thinner at the blade tip (T1) than at the base (T2), reducing mass. A cap (50) may be attached to the blade tip. A mounting lug (58) may be forged (60) on the airfoil base and then machined, completing the blade for mounting in a turbine rotor disk.

  20. Compressor airfoil tip clearance optimization system

    Energy Technology Data Exchange (ETDEWEB)

    Little, David A.; Pu, Zhengxiang

    2015-08-18

    A compressor airfoil tip clearance optimization system for reducing a gap between a tip of a compressor airfoil and a radially adjacent component of a turbine engine is disclosed. The turbine engine may include ID and OD flowpath boundaries configured to minimize compressor airfoil tip clearances during turbine engine operation in cooperation with one or more clearance reduction systems that are configured to move the rotor assembly axially to reduce tip clearance. The configurations of the ID and OD flowpath boundaries enhance the effectiveness of the axial movement of the rotor assembly, which includes movement of the ID flowpath boundary. During operation of the turbine engine, the rotor assembly may be moved axially to increase the efficiency of the turbine engine.

  1. Multi-pass cooling for turbine airfoils

    Science.gov (United States)

    Liang, George

    2011-06-28

    An airfoil for a turbine vane of a gas turbine engine. The airfoil includes an outer wall having pressure and suction sides, and a radially extending cooling cavity located between the pressure and suction sides. A plurality of partitions extend radially through the cooling cavity to define a plurality of interconnected cooling channels located at successive chordal locations through the cooling cavity. The cooling channels define a serpentine flow path extending in the chordal direction. Further, the cooling channels include a plurality of interconnected chambers and the chambers define a serpentine path extending in the radial direction within the serpentine path extending in the chordal direction.

  2. Blowing Circulation Control on a Seaplane Airfoil

    Science.gov (United States)

    Guo, B. D.; Liu, P. Q.; Qu, Q. L.

    2011-09-01

    RANS simulations are presented for blowing circulation control on a seaplane airfoil. Realizable k-epsilon turbulent model and pressure-based coupled algorithm with second-order discretization were adopted to simulate the compressible flow. Both clear and simple flap configuration were simulated with blowing momentum coefficient Cμ = 0, 0.15 and 0.30. The results show that blowing near the airfoil trailing edge could enhance the Coanda effect, delay the flow separation, and increase the lift coefficient dramatically. The blowing circulation control is promising to apply to taking off and landing of an amphibious aircraft or seaplane.

  3. EUDP project 'Low noise airfoil' - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bertagnolio, F. (ed.)

    2012-06-15

    This document summarizes the scientific results achieved during the EUDP-funded project 'Low-Noise Airfoil'. The goals of this project are, on one side to develop a measurement technique that permits the evaluation of trailing edge noise in a classical aerodynamic wind tunnel, and on the other side to develop and implement a design procedure to manufacture airfoil profiles with low noise emission. The project involved two experimental campaigns: one in the LM Wind Power wind tunnel, a classical aerodynamic wind tunnel, in Lunderskov (Denmark), the second one in the Virginia Tech Stability Wind Tunnel at the Aerospace and Ocean Engineering Department of Virginia Tech (Blacksburg, VA, USA), also a classical aerodynamic wind tunnel but equipped with an anechoic chamber that allow to perform acoustic measurements. On the theoretical side, the above experiments yield a series of model validations and improvements. In particular, the so-called TNO trailing edge noise model could be significantly improved by introducing turbulence anisotropy in its formulation, as well as the influence of the boundary layer mean pressure gradient. This two characteristics are inherent to airfoil flows but were neglected in the original approach. In addition, the experimental results are confronted to detailed Large Eddy Simulations of the airfoil flow giving more insight into the flow turbulence characteristics. The methodology which consists in measuring surface pressure spectra directly on the airfoil surface using flush-mounted microphones in order to evaluate far-field noise emission using additional theoretical results has been validated. This technique presents the advantage that it can easily be used in a classical aerodynamic wind tunnel and does not require the use of an anechoic facility. It was developed as a substitute to the original plan that consisted in measuring acoustic waves using hot-wire velocimetry. This last technique proved ineffective in the LM Wind

  4. Wind tunnel tests of the Risoe-A1-18, Risoe-A1-21 and Risoe-A1-24 airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Fuglsang, P.; Dahl, K.S.; Antoniou, I.

    1999-06-01

    This report contains 2D measurements of the Risoe-A1-18, Risoe-A1-21 and Risoe-A1-24 airfoils. The aerodynamic properties were derived from pressure measurements on the airfoil surface and in the wake. The VELUX open jet wind tunnel was used having a background turbulence intensity of 1%, a flow velocity of 42 m/s and a Reynolds number of 1.6x10{sup 6}. The airfoil sections had a chord of 0.60 m and a span of 1.9 m and and plates were used to minimise 3D flow effects. The measurements comprised both static and dynamic inflow where dynamic inflow was obtained by pitching the airfoil in a harmonic motion. We tested the influence of leading edge roughness, vortex generators and Gurney flaps both individually and in combination. For smooth surface conditions, all three airfoils had the desirable properties of constant lift curve slope and low drag coefficient until the maximum lift of about 1.4 was reached. The Risoe-A1-18 airfoil had a smooth post stall whereas the Risoe-A1-21 and Risoe-A1-24 airfoils had a significant drop in the lift coefficient after stall. Test on all airfoil sections mounted with zigzag tape showed that the airfoils were insensitive to leading edge roughness. However with a drop in the maximum lift coefficient to about 1.2. Mounting of delta wing shaped vortex generators and Gurney flaps showed that there was room for a significant increase in the maximum lift coefficient, which was increased to 1.90 for Risoe-A1-24 with vortex generators located at 15% chord. The combination of vortex generators and Gurney flaps increased the maximum lift coefficient to about 2.0. (au) EFP-98. 16 tabs., 98 ills., 10 refs.

  5. Optimization design of airfoil profiles based on the noise of wind turbines

    DEFF Research Database (Denmark)

    Chen, Jin; Cheng, Jiangtao; Shen, Wenzhong; Zhu, Weijun; Wang, Xudong

    2012-01-01

    Based on design theory of airfoil profiles and airfoil self-noise prediction model, a new method with the target of the airfoil average efficiency-noise ratio of design ranges for angle of attack had been developed for designing wind turbine airfoils. The airfoil design method was optimized for a...

  6. APPROXIMATION OF FREE-FORM CURVE – AIRFOIL SHAPE

    Directory of Open Access Journals (Sweden)

    CHONG PERK LIN

    2013-12-01

    Full Text Available Approximation of free-form shape is essential in numerous engineering applications, particularly in automotive and aircraft industries. Commercial CAD software for the approximation of free-form shape is based almost exclusively on parametric polynomial and rational parametric polynomial. The parametric curve is defined by vector function of one independent variable R(u = (x(u, y(u, z(u, where 0≤u≤1. Bézier representation is one of the parametric functions, which is widely used in the approximating of free-form shape. Given a string of points with the assumption of sufficiently dense to characterise airfoil shape, it is desirable to approximate the shape with Bézier representation. The expectation is that the representation function is close to the shape within an acceptable working tolerance. In this paper, the aim is to explore the use of manual and automated methods for approximating section curve of airfoil with Bézier representation.

  7. Aerodynamic Simulation of Ice Accretion on Airfoils

    Science.gov (United States)

    Broeren, Andy P.; Addy, Harold E., Jr.; Bragg, Michael B.; Busch, Greg T.; Montreuil, Emmanuel

    2011-01-01

    This report describes recent improvements in aerodynamic scaling and simulation of ice accretion on airfoils. Ice accretions were classified into four types on the basis of aerodynamic effects: roughness, horn, streamwise, and spanwise ridge. The NASA Icing Research Tunnel (IRT) was used to generate ice accretions within these four types using both subscale and full-scale models. Large-scale, pressurized windtunnel testing was performed using a 72-in.- (1.83-m-) chord, NACA 23012 airfoil model with high-fidelity, three-dimensional castings of the IRT ice accretions. Performance data were recorded over Reynolds numbers from 4.5 x 10(exp 6) to 15.9 x 10(exp 6) and Mach numbers from 0.10 to 0.28. Lower fidelity ice-accretion simulation methods were developed and tested on an 18-in.- (0.46-m-) chord NACA 23012 airfoil model in a small-scale wind tunnel at a lower Reynolds number. The aerodynamic accuracy of the lower fidelity, subscale ice simulations was validated against the full-scale results for a factor of 4 reduction in model scale and a factor of 8 reduction in Reynolds number. This research has defined the level of geometric fidelity required for artificial ice shapes to yield aerodynamic performance results to within a known level of uncertainty and has culminated in a proposed methodology for subscale iced-airfoil aerodynamic simulation.

  8. Near-wall serpentine cooled turbine airfoil

    Science.gov (United States)

    Lee, Ching-Pang

    2014-10-28

    A serpentine coolant flow path is formed by inner walls in a cavity between pressure and suction side walls of a turbine airfoil, the cavity partitioned by one or more transverse partitions into a plurality of continuous serpentine cooling flow streams each having a respective coolant inlet.

  9. Causal mechanisms in airfoil-circulation formation

    Science.gov (United States)

    Zhu, J. Y.; Liu, T. S.; Liu, L. Q.; Zou, S. F.; Wu, J. Z.

    2015-12-01

    In this paper, we trace the dynamic origin, rather than any kinematic interpretations, of lift in two-dimensional flow to the physical root of airfoil circulation. We show that the key causal process is the vorticity creation by tangent pressure gradient at the airfoil surface via no-slip condition, of which the theoretical basis has been given by Lighthill ["Introduction: Boundary layer theory," in Laminar Boundary Layers, edited by L. Rosenhead (Clarendon Press, 1963), pp. 46-113], which we further elaborate. This mechanism can be clearly revealed in terms of vorticity formulation but is hidden in conventional momentum formulation, and hence has long been missing in the history of one's efforts to understand lift. By a careful numerical simulation of the flow around a NACA-0012 airfoil, and using both Eulerian and Lagrangian descriptions, we illustrate the detailed transient process by which the airfoil gains its circulation and demonstrate the dominating role of relevant dynamical causal mechanisms at the boundary. In so doing, we find that the various statements for the establishment of Kutta condition in steady inviscid flow actually correspond to a sequence of events in unsteady viscous flow.

  10. ANALYSIS OF TRANSONIC FLOW PAST CUSPED AIRFOILS

    Directory of Open Access Journals (Sweden)

    Jiří Stodůlka

    2015-06-01

    Full Text Available Transonic flow past two cusped airfoils is numerically solved and achieved results are analyzed by means of flow behavior and oblique shocks formation.Regions around sharp trailing edges are studied in detail and parameters of shock waves are solved and compared using classical shock polar approach and verified by reduction parameters for symmetric configurations.

  11. Optimization Criteria and Sailplane Airfoil Design

    Czech Academy of Sciences Publication Activity Database

    Popelka, Lukáš; Matějka, Milan

    2007-01-01

    Roč. 30, č. 3 (2007), s. 74-78. ISSN 0744-8996 R&D Projects: GA AV ČR IAA2076403; GA AV ČR(CZ) IAA200760614 Institutional research plan: CEZ:AV0Z20760514 Keywords : aerodynamic optimization * airfoil Subject RIV: BK - Fluid Dynamics

  12. An airfoil for general aviation applications

    Science.gov (United States)

    Selig, Michael S.; Maughmer, Mark D.; Somers, Dan M.

    1990-01-01

    A new airfoil, the NLF(1)-0115, has been recently designed at the NASA Langley Research Center for use in general-aviation applications. During the development of this airfoil, special emphasis was placed on experiences and observations gleaned from other successful general-aviation airfoils. For example, the flight lift-coefficient range is the same as that of the turbulent-flow NACA 23015 airfoil. Also, although beneficial for reducing drag and having large amounts of lift, the NLF(1)-0115 avoids the use of aft loading which can lead to large stick forces if utilized on portions of the wing having ailerons. Furthermore, not using aft loading eliminates the concern that the high pitching-moment coefficient generated by such airfoils can result in large trim drags if cruise flaps are not employed. The NASA NLF(1)-0115 has a thickness of 15 percent. It is designed primarily for general-aviation aircraft with wing loadings of 718 to 958 N/sq m (15 to 20 lb/sq ft). Low profile drag as a result of laminar flow is obtained over the range from c sub l = 0.1 and R = 9x10(exp 6) (the cruise condition) to c sub l = 0.6 and R = 4 x 10(exp 6) (the climb condition). While this airfoil can be used with flaps, it is designed to achieve c(sub l, max) = 1.5 at R = 2.6 x 10(exp 6) without flaps. The zero-lift pitching moment is held at c sub m sub o = 0.055. The hinge moment for a .20c aileron is fixed at a value equal to that of the NACA 63 sub 2-215 airfoil, c sub h = 0.00216. The loss in c (sub l, max) due to leading edge roughness, rain, or insects at R = 2.6 x 10 (exp 6) is 11 percent as compared with 14 percent for the NACA 23015.

  13. Airfoil Ice-Accretion Aerodynamics Simulation

    Science.gov (United States)

    Bragg, Michael B.; Broeren, Andy P.; Addy, Harold E.; Potapczuk, Mark G.; Guffond, Didier; Montreuil, E.

    2007-01-01

    NASA Glenn Research Center, ONERA, and the University of Illinois are conducting a major research program whose goal is to improve our understanding of the aerodynamic scaling of ice accretions on airfoils. The program when it is completed will result in validated scaled simulation methods that produce the essential aerodynamic features of the full-scale iced-airfoil. This research will provide some of the first, high-fidelity, full-scale, iced-airfoil aerodynamic data. An initial study classified ice accretions based on their aerodynamics into four types: roughness, streamwise ice, horn ice, and spanwise-ridge ice. Subscale testing using a NACA 23012 airfoil was performed in the NASA IRT and University of Illinois wind tunnel to better understand the aerodynamics of these ice types and to test various levels of ice simulation fidelity. These studies are briefly reviewed here and have been presented in more detail in other papers. Based on these results, full-scale testing at the ONERA F1 tunnel using cast ice shapes obtained from molds taken in the IRT will provide full-scale iced airfoil data from full-scale ice accretions. Using these data as a baseline, the final step is to validate the simulation methods in scale in the Illinois wind tunnel. Computational ice accretion methods including LEWICE and ONICE have been used to guide the experiments and are briefly described and results shown. When full-scale and simulation aerodynamic results are available, these data will be used to further develop computational tools. Thus the purpose of the paper is to present an overview of the program and key results to date.

  14. The application of the gradient-based adjoint multi-point optimization of single and double shock control bumps for transonic airfoils

    Science.gov (United States)

    Mazaheri, K.; Nejati, A.; Chaharlang Kiani, K.; Taheri, R.

    2015-08-01

    A shock control bump (SCB) is a flow control method which uses local small deformations in a flexible wing surface to considerably reduce the strength of shock waves and the resulting wave drag in transonic flows. Most of the reported research is devoted to optimization in a single flow condition. Here, we have used a multi-point adjoint optimization scheme to optimize shape and location of the SCB. Practically, this introduces transonic airfoils equipped with the SCB which are simultaneously optimized for different off-design transonic flight conditions. Here, we use this optimization algorithm to enhance and optimize the performance of SCBs in two benchmark airfoils, i.e., RAE-2822 and NACA-64A010, over a wide range of off-design Mach numbers. All results are compared with the usual single-point optimization. We use numerical simulation of the turbulent viscous flow and a gradient-based adjoint algorithm to find the optimum location and shape of the SCB. We show that the application of SCBs may increase the aerodynamic performance of an RAE-2822 airfoil by 21.9 and by 22.8 % for a NACA-64A010 airfoil compared to the no-bump design in a particular flight condition. We have also investigated the simultaneous usage of two bumps for the upper and the lower surfaces of the airfoil. This has resulted in a 26.1 % improvement for the RAE-2822 compared to the clean airfoil in one flight condition.

  15. Computations of droplet impingement on airfoils in two-phase flow

    International Nuclear Information System (INIS)

    The aerodynamic effects of leading-edge accretion can raise important safety concerns since the formulation of ice causes severe degradation in aerodynamic performance as compared with the clean airfoil. The objective of this study is to develop a numerical simulation strategy for predicting the particle trajectory around an MS-0317 airfoil in the test section of the NASA Glenn Icing Research Tunnel and to investigate the impingement characteristics of droplets on the airfoil surface. In particular, predictions of the mean velocity and turbulence diffusion using turbulent flow solver and continuous random walk method were desired throughout this flow domain in order to investigate droplet dispersion. The collection efficiency distributions over the airfoil surface in simulations with different numbers of droplets, various integration time-steps and particle sizes were compared with experimental data. The large droplet impingement data indicated the trends in impingement characteristics with respect to particle size; the maximum collection efficiency located at the upper surface near the leading edge, and the maximum value and total collection efficiency were increased as the particle size was increased. The extent of the area impinged on by particles also increased with the increment of the particle size, which is similar as compared with experimental data

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2014-06-01

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

  18. Theoretical performances of double Gurney Flap equipped the VAWTs

    Directory of Open Access Journals (Sweden)

    Horia DUMITRESCU

    2012-12-01

    Full Text Available A Gurney flap is simply a flat plate attached perpendicularly to the lower surface of an airfoil or wing trailing edge. A T-strip or double Gurney flap is attached to both the upper and lower surfaces. T-strips are used to modify the lifting characteristics of the baseline airfoil for vertical axis wind rotor turbines. Generally, T-strips have been used during developmental flight test as simple add-on “fixes” to improve the performances of existing aircraft vertical tails. This paper aims to investigate the performances of VAWTs equipped with T-strip on blades trailing edge.

  19. Quiet airfoils for small and large wind turbines

    Science.gov (United States)

    Tangler, James L.; Somers, Dan L.

    2012-06-12

    Thick airfoil families with desirable aerodynamic performance with minimal airfoil induced noise. The airfoil families are suitable for a variety of wind turbine designs and are particularly well-suited for use with horizontal axis wind turbines (HAWTs) with constant or variable speed using pitch and/or stall control. In exemplary embodiments, a first family of three thick airfoils is provided for use with small wind turbines and second family of three thick airfoils is provided for use with very large machines, e.g., an airfoil defined for each of three blade radial stations or blade portions defined along the length of a blade. Each of the families is designed to provide a high maximum lift coefficient or high lift, to exhibit docile stalls, to be relatively insensitive to roughness, and to achieve a low profile drag.

  20. New airfoils for small horizontal axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Giguere, P.; Selig, M.S. [Univ. of Illinois, Urbana, IL (United States)

    1997-12-31

    In a continuing effort to enhance the performance of small energy systems, one root airfoil and three primary airfoils were specifically designed for small horizontal axis wind turbines. These airfoils are intended primarily for 1-10 kW variable-speed wind turbines for both conventional (tapered/twisted) or pultruded blades. The four airfoils were wind-tunnel tested at Reynolds numbers between 100,000 and 500,000. Tests with simulated leading-edge roughness were also conducted. The results indicate that small variable-speed wind turbines should benefit from the use of the new airfoils which provide enhanced lift-to-drag ratio performance as compared with previously existing airfoils.

  1. Turbine airfoil with laterally extending snubber having internal cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Scribner, Carmen Andrew; Messmann, Stephen John; Marsh, Jan H.

    2016-09-06

    A turbine airfoil usable in a turbine engine and having at least one snubber with a snubber cooling system positioned therein and in communication with an airfoil cooling system is disclosed. The snubber may extend from the outer housing of the airfoil toward an adjacent turbine airfoil positioned within a row of airfoils. The snubber cooling system may include an inner cooling channel separated from an outer cooling channel by an inner wall. The inner wall may include a plurality of impingement cooling orifices that direct impingement fluid against an outer wall defining the outer cooling channel. In one embodiment, the cooling fluids may be exhausted from the snubber, and in another embodiment, the cooling fluids may be returned to the airfoil cooling system. Flow guides may be positioned in the outer cooling channel, which may reduce cross-flow by the impingement orifices, thereby increasing effectiveness.

  2. Characterization of the Effect of Wing Surface Instrumentation on UAV Airfoil Performance

    Science.gov (United States)

    Ratnayake, Nalin A.

    2009-01-01

    Recently proposed flight research at NASA Dryden Flight Research Center (DFRC) has prompted study into the aerodynamic effects of modifications made to the surfaces of laminar airfoils. The research is focused on the high-aspect ratio, laminar-flow type wings commonly found on UAVs and other aircraft with a high endurance requirement. A broad range of instrumentation possibilities, such as structural, pressure, and temperature sensing devices may require the alteration of the airfoil outer mold line as part of the installation process. This study attempts to characterize the effect of installing this additiona1 instrumentation on key airfoil performance factors, such as transition location, lift and drag curves, and stall point. In particular, the general case of an airfoil that is channeled in the spanwise direction is considered, and the impact on key performance characteristics is assessed. Particular attention is focused on exploring the limits of channel depth and low-Reynolds number on performance and stall characteristics. To quantify the effect of increased skin friction due to premature transition caused by protruding or recessed instrumentation, two simplified, conservative scenarios are used to consider two potential sources of diaturbance: A) that leading edge alterations would cause linearly expanding areas (triangles) of turbulent flow on both surfaces of the wing upstream of the natural transition point, and B) that a channel or bump on the upper surface would trip turbulent flow across the whole upper surface upstream of the natural transition point. A potentially more important consideration than the skin friction drag increment is the change in overall airfoil performance due to the installation of instrumentation along most of the wingspan. To quantify this effect, 2D CFD simulations of the flow over a representative mid-span airfoil section were conducted in order to assess the change in lift and drag curves for the airfoil in the presence of

  3. Design Of An Aerodynamic Measurement System For Unmanned Aerial Vehicle Airfoils

    Directory of Open Access Journals (Sweden)

    L. Velázquez-Araque

    2012-10-01

    Full Text Available This paper presents the design and validation of a measurement system for aerodynamic characteristics of unmanned aerial vehicles. An aerodynamic balance was designed in order to measure the lift, drag forces and pitching moment for different airfoils. During the design process, several aspects were analyzed in order to produce an efficient design, for instance the range of changes of the angle of attack with and a small increment and the versatility of being adapted to different type of airfoils, since it is a wire balance it was aligned and calibrated as well. Wind tunnel tests of a two dimensional NACA four digits family airfoil and four different modifications of this airfoil were performed to validate the aerodynamic measurement system. The modification of this airfoil was made in order to create a blowing outlet with the shape of a step on the suction surface. Therefore, four different locations along the cord line for this blowing outlet were analyzed. This analysis involved the aerodynamic performance which meant obtaining lift, drag and pitching moment coefficients curves as a function of the angle of attack experimentally for the situation where the engine of the aerial vehicle is turned off, called the no blowing condition, by means of wind tunnel tests. The experiments were performed in a closed circuit wind tunnel with an open test section. Finally, results of the wind tunnel tests were compared with numerical results obtained by means of computational fluid dynamics as well as with other experimental references and found to be in good agreement.

  4. Symmetric airfoil geometry effects on leading edge noise

    OpenAIRE

    Gill, James; Zhang, Xin; Joseph, Phillip F.

    2013-01-01

    Computational aeroacoustic methods are applied to the modeling of noise due to interactions between gusts and the leading edge of real symmetric airfoils. Single frequency harmonic gusts are interacted with various airfoil geometries at zero angle of attack. The effects of airfoil thickness and leading edge radius on noise are investigated systematically and independently for the first time, at higher frequencies than previously used in computational methods. Increases in both leading edge ra...

  5. Improving CAP-TSD steady pressure solutions through airfoil slope modification

    Science.gov (United States)

    Mitterer, Kent F.; Maughmer, Mark D.; Silva, Walter A.; Batina, John T.

    1996-01-01

    A modification of airfoil section geometry is examined for improvement of the leading edge pressures predicted by the Computational Aeroelasticity Program - Transonic Small Disturbance (CAP-TSD). Results are compared with Eppler solutions to assess improvement. Preliminary results indicate that a fading function modification of section slopes is capable of significant improvements in the pressures near the leading edge computed by CAP-TSD. Application of this modification to airfoil geometry before use in CAP-TSD is shown to reduce the nonphysical pressure peak predicted by the transonic small disturbance solver. A second advantage of the slope modification is the substantial reduction in sensitivity of CAP-TSD steady pressure solutions to the computational mesh.

  6. Turbine airfoil with ambient cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Jr, Christian X.; Marra, John J.; Marsh, Jan H.

    2016-06-07

    A turbine airfoil usable in a turbine engine and having at least one ambient air cooling system is disclosed. At least a portion of the cooling system may include one or more cooling channels configured to receive ambient air at about atmospheric pressure. The ambient air cooling system may have a tip static pressure to ambient pressure ratio of at least 0.5, and in at least one embodiment, may include a tip static pressure to ambient pressure ratio of between about 0.5 and about 3.0. The cooling system may also be configured such that an under root slot chamber in the root is large to minimize supply air velocity. One or more cooling channels of the ambient air cooling system may terminate at an outlet at the tip such that the outlet is aligned with inner surfaces forming the at least one cooling channel in the airfoil to facilitate high mass flow.

  7. Turbine engine airfoil and platform assembly

    Science.gov (United States)

    Campbell, Christian X.; James, Allister W.; Morrison, Jay A.

    2012-07-31

    A turbine airfoil (22A) is formed by a first process using a first material. A platform (30A) is formed by a second process using a second material that may be different from the first material. The platform (30A) is assembled around a shank (23A) of the airfoil. One or more pins (36A) extend from the platform into holes (28) in the shank (23A). The platform may be formed in two portions (32A, 34A) and placed around the shank, enclosing it. The two platform portions may be bonded to each other. Alternately, the platform (30B) may be cast around the shank (23B) using a metal alloy with better castability than that of the blade and shank, which may be specialized for thermal tolerance. The pins (36A-36D) or holes for them do not extend to an outer surface (31) of the platform, avoiding stress concentrations.

  8. BIFURCATIONS OF AIRFOIL IN INCOMPRESSIBLE FLOW

    Institute of Scientific and Technical Information of China (English)

    LiuFei; YangYiren

    2005-01-01

    Bifurcations of an airfoil with nonlinear pitching stiffness in incompressible flow are investigated. The pitching spring is regarded as a spring with cubic stiffness. The motion equations of the airfoil are written as the four dimensional one order differential equations. Taking air speed and the linear part of pitching stiffness as the parameters, the analytic solutions of the critical boundaries of pitchfork bifurcations and Hopf bifurcations are obtained in 2 dimensional parameter plane. The stabilities of the equilibrium points and the limit cycles in different regions of 2 dimensional parameter plane are analyzed. By means of harmonic balance method, the approximate critical boundaries of 2-multiple semi-stable limit cycle bifurcations are obtained, and the bifurcation points of supercritical or subcritical Hopf bifurcation are found. Some numerical simulation results are given.

  9. Design of the LRP airfoil series using 2D CFD

    International Nuclear Information System (INIS)

    This paper describes the design and wind tunnel testing of a high-Reynolds number, high lift airfoil series designed for wind turbines. The airfoils were designed using direct gradient- based numerical multi-point optimization based on a Bezier parameterization of the shape, coupled to the 2D Navier-Stokes flow solver EllipSys2D. The resulting airfoils, the LRP2-30 and LRP2-36, achieve both higher operational lift coefficients and higher lift to drag ratios compared to the equivalent FFA-W3 airfoils

  10. Damping element for reducing the vibration of an airfoil

    Science.gov (United States)

    Campbell, Christian X; Marra, John J

    2013-11-12

    An airfoil (10) is provided with a tip (12) having an opening (14) to a center channel (24). A damping element (16) is inserted within the opening of the center channel, to reduce an induced vibration of the airfoil. The mass of the damping element, a spring constant of the damping element within the center channel, and/or a mounting location (58) of the damping element within the center channel may be adjustably varied, to shift a resonance frequency of the airfoil outside a natural operating frequency of the airfoil.

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

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong

    2013-01-01

    objective of high Cp and small chord length. When the airfoils are obtained, the optimum flow angle and rotor solidity are calculated which forms the basic input to the blade design. The new airfoils are designed based on the previous in-house airfoil family which were optimized at a Reynolds number of 3......-stream Mach number of 0.25 at the blade tip. Results show that these new airfoils achieve high power coefficient in a wide range of angles of attack (AOA) and they are extremely insensitive to surface roughness....

  12. Design of the LRP airfoil series using 2D CFD

    DEFF Research Database (Denmark)

    Zahle, Frederik; Bak, Christian; Sørensen, Niels N.;

    2014-01-01

    This paper describes the design and wind tunnel testing of a high-Reynolds number, high lift airfoil series designed for wind turbines. The airfoils were designed using direct gradient- based numerical multi-point optimization based on a Bezier parameterization of the shape, coupled to the 2D...... Navier-Stokes flow solver EllipSys2D. The resulting airfoils, the LRP2-30 and LRP2-36, achieve both higher operational lift coefficients and higher lift to drag ratios compared to the equivalent FFA-W3 airfoils....

  13. Low Reynolds number airfoils for small horizontal axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Giguere, Philippe; Selig, Michael S. [University of Illinois at Urbana-Chanpaign (United States). Dept. of Aeronautical and Astronautical Engineering

    1997-12-31

    To facilitate the airfoil selection process for small horizontal-axis wind turbines, an extensive database of low Reynolds number airfoils has been generated. The database, which consists of lift and drag data, was obtained from experiments conducted in the same wind tunnel testing facility. Experiments with simulated leading-edge roughness were also performed to model the effect of blade erosion and the accumulation of roughness elements, such as insect debris, on airfoil performance. Based on the lift curves and drag polars, guidelines that should be useful in selecting appropriate airfoils for particular blade designs are given. Some of these guidelines are also applicable to larger HAWTs. (author)

  14. CFD study of thick flatback airfoils using OpenFOAM

    OpenAIRE

    Milián Sanz, José María

    2010-01-01

    New airfoil designs are created in order to improve both the structural and aerodynamic properties of a wind turbine blade, one example of these are flatback airfoils. Furthermore, a new CFD programme exists in order to study the behavior of the flow around an airfoil, OpenFOAM. The flow around these new airfoils using OpenFOAM is studied in the present thesis. It is used the turbulence model k-! SST for fully turbulent boundary layer and free transition at the boundary layer, modeled with th...

  15. 23 CFR 140.910 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Equipment. 140.910 Section 140.910 Highways FEDERAL... Railroad Work § 140.910 Equipment. (a) Company owned equipment. Cost of company-owned equipment may be... equipment. Where company owned equipment is not available, reimbursement will be limited to the amount...

  16. S822 and S823 Airfoils: October 1992--December 1993

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D. M.

    2005-01-01

    A family of thick airfoils for 3- to 10-meter, stall-regulated, horizontal-axis wind turbines, the S822 and S823, has been designed and analyzed theoretically. The primary objectives of restrained maximum lift, insensitive to roughness, and low profile have been achieved. The constraints on the pitching moments and airfoil thicknesses have been satisfied.

  17. Investigations of the transonic flow around oscillating airfoils

    NARCIS (Netherlands)

    Tijdeman, H.

    1977-01-01

    Exploratory wind-tunnel experiments in high-subsonic and transonic flow on a conventional airfoil with oscillating flap and a supercritical airfoil oscillating in pitch are described. In the analysis of the experimental results, emphasis is placed upon the typical aspects of transonic flow, namely t

  18. Bifurcation and chaos analysis for aeroelastic airfoil with freeplay structural nonlinearity in pitch

    International Nuclear Information System (INIS)

    The dynamics character of a two degree-of-freedom aeroelastic airfoil with combined freeplay and cubic stiffness nonlinearities in pitch submitted to supersonic and hypersonic flow has been gaining significant attention. The Poincaré mapping method and Floquet theory are adopted to analyse the limit cycle oscillation flutter and chaotic motion of this system. The result shows that the limit cycle oscillation flutter can be accurately predicted by the Floquet multiplier. The phase trajectories of both the pitch and plunge motion are obtained and the results show that the plunge motion is much more complex than the pitch motion. It is also proved that initial conditions have important influences on the dynamics character of the airfoil system. In a certain range of airspeed and with the same system parameters, the stable limit cycle oscillation, chaotic and multi-periodic motions can be detected under different initial conditions. The figure of the Poincaré section also approves the previous conclusion

  19. Airfoil family design for large offshore wind turbine blades

    International Nuclear Information System (INIS)

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

  20. A CFD Database for Airfoils and Wings at Post-Stall Angles of Attack

    Science.gov (United States)

    Petrilli, Justin; Paul, Ryan; Gopalarathnam, Ashok; Frink, Neal T.

    2013-01-01

    This paper presents selected results from an ongoing effort to develop an aerodynamic database from Reynolds-Averaged Navier-Stokes (RANS) computational analysis of airfoils and wings at stall and post-stall angles of attack. The data obtained from this effort will be used for validation and refinement of a low-order post-stall prediction method developed at NCSU, and to fill existing gaps in high angle of attack data in the literature. Such data could have potential applications in post-stall flight dynamics, helicopter aerodynamics and wind turbine aerodynamics. An overview of the NASA TetrUSS CFD package used for the RANS computational approach is presented. Detailed results for three airfoils are presented to compare their stall and post-stall behavior. The results for finite wings at stall and post-stall conditions focus on the effects of taper-ratio and sweep angle, with particular attention to whether the sectional flows can be approximated using two-dimensional flow over a stalled airfoil. While this approximation seems reasonable for unswept wings even at post-stall conditions, significant spanwise flow on stalled swept wings preclude the use of two-dimensional data to model sectional flows on swept wings. Thus, further effort is needed in low-order aerodynamic modeling of swept wings at stalled conditions.

  1. Multiple element airfoils optimized for maximum lift coefficient.

    Science.gov (United States)

    Ormsbee, A. I.; Chen, A. W.

    1972-01-01

    Optimum airfoils in the sense of maximum lift coefficient are obtained for incompressible fluid flow at large Reynolds number. The maximum lift coefficient is achieved by requiring that the turbulent skin friction be zero in the pressure rise region on the airfoil upper surface. Under this constraint, the pressure distribution is optimized. The optimum pressure distribution is a function of Reynolds number and the trailing edge velocity. Geometries of those airfoils which will generate these optimum pressure distributions are obtained using a direct-iterative method which is developed in this study. This method can be used to design airfoils consisting of any number of elements. Numerical examples of one- and two-element airfoils are given. The maximum lift coefficients obtained range from 2 to 2.5.

  2. An Experimental Study on Active Flow Control Using Synthetic Jet Actuators over S809 Airfoil

    International Nuclear Information System (INIS)

    This study investigates the effect of periodic excitation from individually controlled synthetic jet actuators on the dynamics of the flow within the separation and re-attachment regions of the boundary layer over the suction surface of a 2D model wing that has S809 airfoil profile. Experiments are performed in METUWIND's C3 open-loop suction type wind tunnel that has a 1 m × 1 m cross-section test section. The synthetic jet array on the wing consists of three individually controlled actuators driven by piezoelectric diaphragms located at 28% chord location near the mid-span of the wing. In the first part of the study, surface pressure, Constant Temperature Anemometry (CTA) and Particle Image Velocimetry (PIV) measurements are performed over the suction surface of the airfoil to determine the size and characteristics of the separated shear layer and the re-attachment region, i.e. the laminar separation bubble, at 2.3x105 Reynolds number at zero angle of attack and with no flow control as a baseline case. For the controlled case, CTA measurements are carried out under the same inlet conditions at various streamwise locations along the suction surface of the airfoil to investigate the effect of the synthetic jet on the boundary layer properties. During the controlled case experiments, the synthetic jet actuators are driven with a sinusoidal frequency of 1.45 kHz and 300Vp-p. Results of this study show that periodic excitation from the synthetic jet actuators eliminates the laminar separation bubble formed over the suction surface of the airfoil at 2.3x105 Reynolds number at zero angle of attack

  3. Active Control of Flow around NACA 0015 Airfoil by Using DBD Plasma Actuator

    Directory of Open Access Journals (Sweden)

    Şanlısoy A.

    2013-04-01

    Full Text Available In this study, effect of plasma actuator on a flat plate and manipulation of flow separation on NACA0015 airfoil with plasma actuator at low Reynolds numbers were experimentally investigated. In the first section of the study, plasma actuator which consists of positive and grounded electrode couple and dielectric layer, located on a flat plate was actuated at different frequencies and peak to peak voltages in range of 3-5 kHz and 6-12 kV respectively. Theinduced air flow velocity on the surface of flat plate was measured by pitot tube at different locations behind the actuator. The influence of dielectricthickness and unsteady actuation with duty cycle was also examined. In the second section, the effect of plasma actuator on NACA0015 airfoil was studied atReynolds number 15000 and 30000. Four plasma actuators were placed at x/C = 0.1, 0.3, 0.5 and 0.9, and different electrode combinations were activated by sinusoidal signal. Flow visualizations were done when the attack angles were 0°, 5°, 10°, 15° and 20°. The results indicate that up to the 15° attack angle, the separated flow was reattached by plasma actuator at 12kV peak to peak voltage and 4 kHz frequency. However, 12 kVpp voltage was insufficient to reattach the flow at 20° angle of attack. The separated flow could be reattached by increasing the voltage up to 13 kV. Lift coefficient was also increased by the manipulated flow over the airfoil. Results showed that even high attack angles, the actuators can control the flow separation and prevent the airfoil from stall at low Reynolds numbers.

  4. Tonal noise production from a wall-mounted finite airfoil

    Science.gov (United States)

    Moreau, Danielle J.; Doolan, Con J.

    2016-02-01

    This study is concerned with the flow-induced noise of a smooth wall-mounted finite airfoil with flat ended tip and natural boundary layer transition. Far-field noise measurements have been taken at a single observer location and with a microphone array in the Virginia Tech Stability Wind Tunnel for a wall-mounted finite airfoil with aspect ratios of L / C = 1 - 3, at a range of Reynolds numbers (ReC = 7.9 ×105 - 1.6 ×106, based on chord) and geometric angles of attack (α = 0 - 6 °). At these Reynolds numbers, the wall-mounted finite airfoil produces a broadband noise contribution with a number of discrete equispaced tones at non-zero angles of attack. Spectral data are also presented for the noise produced due to three-dimensional vortex flow near the airfoil tip and wall junction to show the contributions of these flow features to airfoil noise generation. Tonal noise production is linked to the presence of a transitional flow state to the trailing edge and an accompanying region of mildly separated flow on the pressure surface. The separated flow region and tonal noise source location shift along the airfoil trailing edge towards the free-end region with increasing geometric angle of attack due to the influence of the tip flow field over the airfoil span. Tonal envelopes defining the operating conditions for tonal noise production from a wall-mounted finite airfoil are derived and show that the domain of tonal noise production differs significantly from that of a two-dimensional airfoil. Tonal noise production shifts to lower Reynolds numbers and higher geometric angles of attack as airfoil aspect ratio is reduced.

  5. Reversible airfoils for stopped rotors in high speed flight

    International Nuclear Information System (INIS)

    This study starts with the design of a reversible airfoil rib for stopped-rotor applications, where the sharp trailing-edge morphs into the rounded leading-edge, and vice-versa. A NACA0012 airfoil is approximated in a piecewise linear manner and straight, rigid outer profile links used to define the airfoil contour. The end points of the profile links connect to control links, each set on a central actuation rod via an offset. Chordwise motion of the actuation rod moves the control and the profile links and reverses the airfoil. The paper describes the design methodology and evolution of the final design, based on which two reversible airfoil ribs were fabricated and used to assemble a finite span reversible rotor/wing demonstrator. The profile links were connected by Aluminum strips running in the spanwise direction which provided stiffness as well as support for a pre-tensioned elastomeric skin. An inter-rib connector with a curved-front nose piece supports the leading-edge. The model functioned well and was able to reverse smoothly back-and-forth, on application and reversal of a voltage to the motor. Navier–Stokes CFD simulations (using the TURNS code) show that the drag coefficient of the reversible airfoil (which had a 13% maximum thickness due to the thickness of the profile links) was comparable to that of the NACA0013 airfoil. The drag of a 16% thick elliptical airfoil was, on average, about twice as large, while that of a NACA0012 in reverse flow was 4–5 times as large, even prior to stall. The maximum lift coefficient of the reversible airfoil was lower than the elliptical airfoil, but higher than the NACA0012 in reverse flow operation. (paper)

  6. Research on improved design of airfoil profiles based on the continuity of airfoil surface curvature of wind turbines

    DEFF Research Database (Denmark)

    Chen, Jin; Cheng, Jiangtao; Shen, Wenzhong; Zhu, Weijun; Wang, Xudong

    2013-01-01

    Aerodynamic of airfoil performance is closely related to the continuity of its surface curvature, and airfoil profiles with a better aerodynamic performance plays an important role in the design of wind turbine. The surface curvature distribution along the chord direction and pressure distributio...

  7. Transonic airfoil design for helicopter rotor applications

    Science.gov (United States)

    Hassan, Ahmed A.; Jackson, B.

    1989-01-01

    Despite the fact that the flow over a rotor blade is strongly influenced by locally three-dimensional and unsteady effects, practical experience has always demonstrated that substantial improvements in the aerodynamic performance can be gained by improving the steady two-dimensional charateristics of the airfoil(s) employed. The two phenomena known to have great impact on the overall rotor performance are: (1) retreating blade stall with the associated large pressure drag, and (2) compressibility effects on the advancing blade leading to shock formation and the associated wave drag and boundary-layer separation losses. It was concluded that: optimization routines are a powerful tool for finding solutions to multiple design point problems; the optimization process must be guided by the judicious choice of geometric and aerodynamic constraints; optimization routines should be appropriately coupled to viscous, not inviscid, transonic flow solvers; hybrid design procedures in conjunction with optimization routines represent the most efficient approach for rotor airfroil design; unsteady effects resulting in the delay of lift and moment stall should be modeled using simple empirical relations; and inflight optimization of aerodynamic loads (e.g., use of variable rate blowing, flaps, etc.) can satisfy any number of requirements at design and off-design conditions.

  8. Airfoil for a gas turbine engine

    Science.gov (United States)

    Liang, George

    2011-05-24

    An airfoil is provided for a turbine of a gas turbine engine. The airfoil comprises: an outer structure comprising a first wall including a leading edge, a trailing edge, a pressure side, and a suction side; an inner structure comprising a second wall spaced from the first wall and at least one intermediate wall; and structure extending between the first and second walls so as to define first and second gaps between the first and second walls. The second wall and the at least one intermediate wall define at least one pressure side supply cavity and at least one suction side supply cavity. The second wall may include at least one first opening near the leading edge of the first wall. The first opening may extend from the at least one pressure side supply cavity to the first gap. The second wall may further comprise at least one second opening near the trailing edge of the outer structure. The second opening may extend from the at least one suction side supply cavity to the second gap. The first wall may comprise at least one first exit opening extending from the first gap through the pressure side of the first wall and at least one second exit opening extending from the second gap through the suction side of the second wall.

  9. Computer-aided roll pass design in rolling of airfoil shapes

    Science.gov (United States)

    Akgerman, N.; Lahoti, G. D.; Altan, T.

    1980-01-01

    This paper describes two computer-aided design (CAD) programs developed for modeling the shape rolling process for airfoil sections. The first program, SHPROL, uses a modular upper-bound method of analysis and predicts the lateral spread, elongation, and roll torque. The second program, ROLPAS, predicts the stresses, roll separating force, the roll torque and the details of metal flow by simulating the rolling process, using the slab method of analysis. ROLPAS is an interactive program; it offers graphic display capabilities and allows the user to interact with the computer via a keyboard, CRT, and a light pen. The accuracy of the computerized models was evaluated by (a) rolling a selected airfoil shape at room temperature from 1018 steel and isothermally at high temperature from Ti-6Al-4V, and (b) comparing the experimental results with computer predictions. The comparisons indicated that the CAD systems, described here, are useful for practical engineering purposes and can be utilized in roll pass design and analysis for airfoil and similar shapes.

  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. 7 CFR 550.38 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 6 2010-01-01 2010-01-01 false Equipment. 550.38 Section 550.38 Agriculture... Equipment/property Standards § 550.38 Equipment. (a) The Cooperator shall not use equipment acquired with... the Federal Government retains an interest in the equipment. (b) The Cooperator shall use...

  12. 14 CFR 23.1415 - Ditching equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ditching equipment. 23.1415 Section 23.1415... STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Safety Equipment § 23.1415 Ditching equipment. (a) Emergency flotation and signaling equipment required by any operating rule in...

  13. 14 CFR 25.1415 - Ditching equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ditching equipment. 25.1415 Section 25.1415... STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Safety Equipment § 25.1415 Ditching equipment. (a) Ditching equipment used in airplanes to be certificated for ditching under § 25.801, and required by...

  14. 21 CFR 606.60 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Equipment. 606.60 Section 606.60 Food and Drugs... GOOD MANUFACTURING PRACTICE FOR BLOOD AND BLOOD COMPONENTS Equipment § 606.60 Equipment. (a) Equipment... maintenance. The equipment shall be observed, standardized and calibrated on a regularly scheduled basis...

  15. 21 CFR 225.30 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Equipment. 225.30 Section 225.30 Food and Drugs... Equipment § 225.30 Equipment. (a) Equipment which is designed to perform its intended function and is properly installed and used is essential to the manufacture of medicated feeds. Such equipment...

  16. 21 CFR 226.30 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Equipment. 226.30 Section 226.30 Food and Drugs... Facilities and Equipment § 226.30 Equipment. Equipment used for the manufacture, processing, packaging, bulk... facilitate maintenance and operation for its intended purpose. The equipment shall: (a) Be so...

  17. 14 CFR 27.1415 - Ditching equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ditching equipment. 27.1415 Section 27.1415... STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1415 Ditching equipment. (a) Emergency flotation and signaling equipment required by any operating rule in this chapter must meet the...

  18. 14 CFR 29.1415 - Ditching equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ditching equipment. 29.1415 Section 29.1415... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Safety Equipment § 29.1415 Ditching equipment. (a) Emergency flotation and signaling equipment required by any operating rule of this chapter must meet...

  19. On the Spanwise Uniformity of Wind Tunnel Test Data of Transonic Airfoils

    OpenAIRE

    Ito, Tadashi; Suzuki, Koichi; KAMIYA, Nobuhiko; 伊藤, 忠; 鈴木, 弘一; 神谷, 信彦

    1981-01-01

    The spanwise uniformity of the flow around two-dimensional models of airfoils has been examined for the 100×400 transonic wind tunnel and the 2M×2M transonic wind tunnel. For flows of free-stream Mach numbers below the drag-divergence Mach number, the spanwise uniformity of the section drag coefficient is good in the region around the center section. Although the spanwise uniformity is bad for flows of freestream Mach numbers above that, the drag-divergence Mach number can be obtained accurat...

  20. Performance analysis of double blade airfoil for hydrokinetic turbine applications

    International Nuclear Information System (INIS)

    Highlights: ► We computationally investigated the flow and performance characteristics of a double blade airfoil. ► The double blade airfoil shows high performance comparing with the standard airfoil. ► Using the double blade airfoil, wind and hydrokinetic energy potentials of countries may be redefined and increased accordingly. - Abstract: Hydrokinetic energy holds significant promise as a new, carbon-free energy source. The hydrokinetic turbine harnesses the power from moving water without the construction of a dam. Operational effectiveness of the wind and hydrokinetic turbines depend on the performance of the airfoils chosen. Traditionally, standard airfoils, like NACA and GOTINGEN, are used for wind and hydrokinetic turbines generating energy have the maximum lift coefficient about 1.3 at the stall angle of attack, about 12°. At these values, the flow velocities to produce electric energy are 7 m/s and 3 m/s for wind turbine and hydrokinetic turbine respectively. Using double blade airfoil, the fluid dynamics governing the flow field eliminates the separation bubble by the injection of the high momentum fluid through the gab of the double blade of airfoil by meaning of the flow control delays the stall up to an angle of attack of 20°, with a maximum lift coefficient of 2.06. Hence, using double blade airfoils in the wind and hydrokinetic turbines, minimum wind and hydrokinetic flow velocities to produce economical energies will be 3–4 m/s for wind turbines and 1–1.5 m/s or less for hydrokinetic turbines. Consequently, the wind power and hydrokinetic potentials of Turkey will be re-defined and increased accordingly.

  1. 43 CFR 12.934 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Equipment. 12.934 Section 12.934 Public....934 Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions of this section. (b) The recipient shall not use equipment acquired...

  2. 29 CFR 95.34 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Equipment. 95.34 Section 95.34 Labor Office of the Secretary... Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions of this section. (b) The recipient shall not use equipment acquired with...

  3. 34 CFR 74.34 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Equipment. 74.34 Section 74.34 Education Office of the... Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions of this section. (b) The recipient may not use equipment acquired with Federal...

  4. 7 CFR 3019.34 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Equipment. 3019.34 Section 3019.34 Agriculture....34 Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions of this section. (b) The recipient shall not use equipment acquired...

  5. 45 CFR 74.34 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Equipment. 74.34 Section 74.34 Public Welfare... COMMERCIAL ORGANIZATIONS Post-Award Requirements Property Standards § 74.34 Equipment. (a) Title to equipment... section. (b)(1) The recipient shall not use equipment acquired with HHS funds to provide services to...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  7. Design and experimental results for the S805 airfoil

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D.M. [Airfoils, Inc., State College, PA (United States)

    1997-01-01

    An airfoil for horizontal-axis wind-turbine applications, the S805, has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of restrained maximum lift, insensitive to roughness, and low profile drag have been achieved. The airfoil also exhibits a docile stall. Comparisons of the theoretical and experimental results show good agreement. Comparisons with other airfoils illustrate the restrained maximum lift coefficient as well as the lower profile-drag coefficients, thus confirming the achievement of the primary objectives.

  8. Design and experimental results for the S809 airfoil

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D M [Airfoils, Inc., State College, PA (United States)

    1997-01-01

    A 21-percent-thick, laminar-flow airfoil, the S809, for horizontal-axis wind-turbine applications, has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of restrained maximum lift, insensitive to roughness, and low profile drag have been achieved. The airfoil also exhibits a docile stall. Comparisons of the theoretical and experimental results show good agreement. Comparisons with other airfoils illustrate the restrained maximum lift coefficient as well as the lower profile-drag coefficients, thus confirming the achievement of the primary objectives.

  9. Geometrical effects on the airfoil flow separation and transition

    KAUST Repository

    Zhang, Wei

    2015-04-25

    We present results from direct numerical simulations (DNS) of incompressible flow over two airfoils, NACA-4412 and NACA-0012-64, to investigate the effects of the airfoil geometry on the flow separation and transition patterns at Re=104 and 10 degrees incidence. The two chosen airfoils are geometrically similar except for maximum camber (respectively 4%C and 0 with C the chord length), which results in a larger projection area with respect to the incoming flow for the NACA-4412 airfoil, and a larger leeward surface curvature at the leading edge for the NACA-0012-64 airfoil. The governing equations are discretized using an energy conservative fourth-order spatial discretization scheme. An assessment on the two-point correlation indicates that a spanwise domain size of 0.8C is sufficiently large for the present simulations. We discuss flow separation at the airfoil leading edge, transition of the separated shear layer to three-dimensional flow and subsequently to turbulence. Numerical results reveal a stronger adverse pressure gradient field in the leading edge region of the NACA-0012-64 airfoil due to the rapidly varying surface curvature. As a result, the flow experiences detachment at x/C=0.08, and the separated shear layer transition via Kelvin-Helmholtz mechanism occurs at x/C=0.29 with fully developed turbulent flow around x/C=0.80. These flow development phases are delayed to occur at much downstream positions, respectively, observed around x/C=0.25, 0.71 and 1.15 for the NACA-4412 airfoil. The turbulent intensity, measured by the turbulent fluctuations and turbulent Reynolds stresses, are much larger for NACA-0012-64 from the transition onset until the airfoil trailing edge, while turbulence develops significantly downstream of the trailing edge for the NACA-4412 airfoil. For both airfoils, our DNS results indicate that the mean Reynolds stress u\\'u\\'/U02 reaches its maximum value at a distance from the surface approximately equal to the displacement

  10. 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...

  11. Customized airfoils and their impact on VAWT cost of energy

    Science.gov (United States)

    Berg, Dale E.

    1990-08-01

    Sandia National Laboratories has developed a family of airfoils specifically designed for use in the equatorial portion of a Vertical-Axis Wind Turbine (VAWT) blade. An airfoil of that family has been incorporated into the rotor blades of the DOE/Sandia 34-m diameter VAWT Test Bed. The airfoil and rotor design process is reviewed. Comparisons with data recently acquired from flow visualization tests and from the DOE/Sandia 34-m diameter VAWT Test Bed illustrate the success that was achieved in the design. The economic optimization model used in the design is described and used to evaluate the effect of modifications to the current Test Bed blade.

  12. 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...

  13. 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...

  14. 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...

  15. Reduced-Order Model Development for Airfoil Forced Response

    Directory of Open Access Journals (Sweden)

    Ramana V. Grandhi

    2008-04-01

    Full Text Available Two new reduced-order models are developed to accurately and rapidly predict geometry deviation effects on airfoil forced response. Both models have significant application to improved mistuning analysis. The first developed model integrates a principal component analysis approach to reduce the number of defining geometric parameters, semianalytic eigensensitivity analysis, and first-order Taylor series approximation to allow rapid as-measured airfoil response analysis. A second developed model extends this approach and quantifies both random and bias errors between the reduced and full models. Adjusting for the bias significantly improves reduced-order model accuracy. The error model is developed from a regression analysis of the relationship between airfoil geometry parameters and reduced-order model error, leading to physics-based error quantification. Both models are demonstrated on an advanced fan airfoil's frequency, modal force, and forced response.

  16. Design and experimental results for the S814 airfoil

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D.M. [Airfoils, Inc., State College, PA (United States)

    1997-01-01

    A 24-percent-thick airfoil, the S814, for the root region of a horizontal-axis wind-turbine blade has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of high maximum lift, insensitive to roughness, and low profile drag have been achieved. The constraints on the pitching moment and the airfoil thickness have been satisfied. Comparisons of the theoretical and experimental results show good agreement with the exception of maximum lift which is overpredicted. Comparisons with other airfoils illustrate the higher maximum lift and the lower profile drag of the S814 airfoil, thus confirming the achievement of the objectives.

  17. Turbine airfoil with a compliant outer wall

    Science.gov (United States)

    Campbell, Christian X.; Morrison, Jay A.

    2012-04-03

    A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation in the outer layer is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a support structure. The outer layer may be a compliant layer configured such that the outer layer may thermally expand and thereby reduce the stress within the outer layer. The outer layer may be formed from a nonplanar surface configured to thermally expand. In another embodiment, the outer layer may be planar and include a plurality of slots enabling unrestricted thermal expansion in a direction aligned with the outer layer.

  18. Cooled airfoil in a turbine engine

    Energy Technology Data Exchange (ETDEWEB)

    Vitt, Paul H; Kemp, David A; Lee, Ching-Pang; Marra, John J

    2015-04-21

    An airfoil in a gas turbine engine includes an outer wall and an inner wall. The outer wall includes a leading edge, a trailing edge opposed from the leading edge in a chordal direction, a pressure side, and a suction side. The inner wall is coupled to the outer wall at a single chordal location and includes portions spaced from the pressure and suction sides of the outer wall so as to form first and second gaps between the inner wall and the respective pressure and suction sides. The inner wall defines a chamber therein and includes openings that provide fluid communication between the respective gaps and the chamber. The gaps receive cooling fluid that provides cooling to the outer wall as it flows through the gaps. The cooling fluid, after traversing at least substantial portions of the gaps, passes into the chamber through the openings in the inner wall.

  19. AirborneWind Energy: Airfoil-Airmass Interaction

    OpenAIRE

    Zanon, Mario; Gros, Sebastien; Meyers, Johan; Diehl, Moritz

    2014-01-01

    The Airborne Wind Energy paradigm proposes to generate energy by flying a tethered airfoil across the wind flow at a high velocity. While Airborne Wind Energy enables flight in higher-altitude, stronger wind layers, the extra drag generated by the tether motion imposes a significant limit to the overall system efficiency. To address this issue, two airfoils with a shared tether can reduce overall system drag. A study proposed in Zanon et al. (2013) confirms this claim by showing that, in the ...

  20. Response of a Thin Airfoil Encountering a Strong Density Discontinuity

    OpenAIRE

    Marble, F. E.

    1993-01-01

    Airfoil theory for unsteady motion has been developed extensively assuming the undisturbed medium to be of uniform density, a restriction accurate for motion in the atmosphere, G/auert (1929), Burgers (1935), Theodorsen (1935), Kussner (1936), Karman and Sears (1938), Kinney and Sears (1975). In some instances, notably for airfoils comprising fan, compressor and turbine blade rows, the undisturbed medium may carry density variations or "spots," resulting from non-uniformaties ...

  1. 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...

  2. Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency

    OpenAIRE

    Tuncer, I.H.; Kay, M.

    2004-01-01

    A numerical optimization algorithm based on the steepest decent along the variation of the optimization function is implemented for maximizing the thrust and/or propulsive efficiency of a single flapping airfoil. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver on moving overset grids. The flapping motion of the airfoil is described by a combined sinusoidal plunge and pitching motion. Optimization parameters are taken to be the amplitudes of the plunge and pitching ...

  3. Development of Variable Camber Morphing Airfoil Using Corrugated Structure

    OpenAIRE

    横関, 智弘; 杉浦, 綾; 平野, 義鎭; Yokozeki, Tomohiro; Sugiura, Aya; Hirano, Yoshiyasu

    2014-01-01

    This paper describes the development and the wind tunnel test of a variable geometry morphing airfoil using corrugated structures. Proof-of-concept study of a morphing wing with corrugated flexible seamless flap-like structure is verified by finite element analysis, and a prototype is manufactured using carbon fiber reinforced plastics. For the actuation system, two servomotors are installed inside the prototype wing to control the airfoil shape by the chordwise tension of the connected wires...

  4. Static aeroelastic response of chiral-core airfoils

    OpenAIRE

    Spadoni, Alessandro; Ruzzene, Massimo

    2007-01-01

    Extensive research is being devoted to the analysis and application of cellular solids for the design of innovative structural components. The chiral geometry in particular features a unique mechanical behavior which is here exploited for the design of 2D airfoils with morphing capabilities. A coupled-physics model, comprising computational fluid dynamics and structural analyses, investigates the influence of the chiral core on the aerodynamic behavior of the airfoil. Specifically, the model ...

  5. 28 CFR 66.32 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Equipment. 66.32 Section 66.32 Judicial... Equipment. (a) The Omnibus Crime Control and Safe Streets Act of 1968, as amended, Public Law 90-351, section 808, requires that the title to all equipment and supplies purchased with section 403 or...

  6. Symmetric airfoil geometry effects on leading edge noise.

    Science.gov (United States)

    Gill, James; Zhang, X; Joseph, P

    2013-10-01

    Computational aeroacoustic methods are applied to the modeling of noise due to interactions between gusts and the leading edge of real symmetric airfoils. Single frequency harmonic gusts are interacted with various airfoil geometries at zero angle of attack. The effects of airfoil thickness and leading edge radius on noise are investigated systematically and independently for the first time, at higher frequencies than previously used in computational methods. Increases in both leading edge radius and thickness are found to reduce the predicted noise. This noise reduction effect becomes greater with increasing frequency and Mach number. The dominant noise reduction mechanism for airfoils with real geometry is found to be related to the leading edge stagnation region. It is shown that accurate leading edge noise predictions can be made when assuming an inviscid meanflow, but that it is not valid to assume a uniform meanflow. Analytic flat plate predictions are found to over-predict the noise due to a NACA 0002 airfoil by up to 3 dB at high frequencies. The accuracy of analytic flat plate solutions can be expected to decrease with increasing airfoil thickness, leading edge radius, gust frequency, and Mach number. PMID:24116405

  7. Intermittent Flow Regimes in a Transonic Fan Airfoil Cascade

    Science.gov (United States)

    Lepicovsky, J.; McFarland, E. R.; Chima, R. V.; Capece, V. R.; Hayden, J.

    2002-01-01

    A study was conducted in the NASA Glenn Research Center linear cascade on the intermittent flow on the suction surface of an airfoil section from the tip region of a modern low aspect ratio fan blade. Experimental results revealed that, at a large incidence angle, a range of transonic inlet Mach numbers exist where the leading-edge shock-wave pattern was unstable. Flush mounted high frequency response pressure transducers indicated large local jumps in the pressure in the leading edge area, which generates large intermittent loading on the blade leading edge. These measurements suggest that for an inlet Mach number between 0.9 and 1.0 the flow is bi-stable, randomly switching between subsonic and supersonic flows. Hence, it appears that the change in overall flow conditions in the transonic region is based on the frequency of switching between two stable flow states rather than on the continuous increase of the flow velocity. To date, this flow behavior has only been observed in a linear transonic cascade. Further research is necessary to confirm this phenomenon occurs in actual transonic fans and is not the byproduct of an endwall restricted linear cascade.

  8. Equipment for hydraulic testing

    International Nuclear Information System (INIS)

    Hydraulic testing in boreholes is one major task of the hydrogeological program in the Stripa Project. A new testing equipment for this purpose was constructed. It consists of a downhole part and a surface part. The downhole part consists of two packers enclosing two test-sections when inflated; one between the packers and one between the bottom packer and the bottom of the borehole. A probe for downhole electronics is also included in the downhole equipment together with electrical cable and nylon tubing. In order to perform shut-in and pulse tests with high accuracy a surface controlled downhole valve was constructed. The surface equipment consists of the data acquisition system, transducer amplifier and surface gauges. In the report detailed descriptions of each component in the whole testing equipment are given. (Auth.)

  9. Optimization Method for Turbine Airfoil Designing Using Genetic Algorithms, CFD and Parallel Computing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An optimization method to design turbine airfoils using a Genetic Algorithm (GA) design shell coupled directly with a viscous CFD (Computational Fluid Dynamics) analysis code is proposed in this paper. The blade geometry is parameterized and the optimization method is used to search for a blade geometry that will minimize the loss in the turbine cascade passage. The viscous flow prediction code is verified by the experimental data of cascade, which is typical for a gas turbine rotor blade section. A comparative study of the blades designed by the optimization technique and the original one is presented

  10. Analysis of Location of Laminar-Turbulent Transition on the FX 66-S-196 V1 Airfoil

    Directory of Open Access Journals (Sweden)

    Laurynas Naujokaitis

    2011-04-01

    Full Text Available The transition location on the FX 66‑S‑196 V1 wing section was analyzed with the using interactive program XFOIL of Mark Drela, MIT. Calculated results of transition location were compared with published measurement data from a wind tunnel at Delft University of Technology (Netherlands. The airfoil was analyzed at the Reynolds number Re = 0,5·106 and Re = 1,5·106. Article in Lithuanian

  11. Nomogram for correcting drag and angle of attack of an airfoil model in an air stream of finite diameter

    Science.gov (United States)

    1924-01-01

    In experimenting with airfoil models in a wind tunnel, the magnitude of the forces acting on the model is affected by the fact that the air stream in which the model is suspended, has a restricted cross-section. In order to utilize the results for an airplane in an unlimited quantity of air, a correction must be made. The magnitude of this correction was determined by Prandtl by the application of his wing theory.

  12. Design and Validation of a Force Measurement System for the Analysis of Airfoil Lift and Drag Characteristics

    OpenAIRE

    Manning, Niall

    2010-01-01

    One of the aims of this research was to reduce the flow separation and therefore the pressure drag generated by a wing section, through the adding of surface modifications. The modifications consisted of roughening the surface of polystyrene airfoils using a sand blasting technique, which resulted in a dimpled surface. This idea originated from the design of a golf ball, as the dimples are known to delay flow separation which allows the ball to travel further. In relation to wing design, ther...

  13. Assessment of the aerodynamic characteristics of thick airfoils in high Reynolds and moderate Ma numbers using CFD modeling

    Science.gov (United States)

    Prospathopoulos, John M.; Papadakis, Giorgos; Sieros, Giorgos; Voutsinas, Spyros G.; Chaviaropoulos, Takis K.; Diakakis, Kostas

    2014-06-01

    The aerodynamic characteristics of thick airfoils in high Reynolds number is assessed using two different CFD RANS solvers: the compressible MaPFlow and the incompressible CRES-flowNS-2D both equipped with the k-ω SST turbulence model. Validation is carried out by comparing simulations against existing high Reynolds experimental data for the NACA 63-018 airfoil in the range of -10° to 20°. The use of two different solvers aims on one hand at increasing the credibility in the results and on the other at quantifying the compressibility effects. Convergence of steady simulations is achieved within a mean range of -10° to 14° which refers to attached or light stall conditions. Over this range the simulations from the two codes are in good agreement. As stall gets deeper, steady convergence ceases and the simulations must switch to unsteady. Lift and drag oscillations are produced which increase in amplitude as the angle of attack increases. Finally in post stall, the average CL is found to decrease up to ~24° or 32° for the FFA or the NACA 63-018 airfoils respectively, and then recover to higher values indicating a change in the unsteady features of the flow.

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

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac

    2015-01-01

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

  15. Numerical study of the static and pitching RISOe-B1-18 airfoil[STALL

    Energy Technology Data Exchange (ETDEWEB)

    Bertagnolio, F.

    2004-01-01

    The objective of this report is the better understanding of the physics of the aeroelastic motion of wind turbine blades in order to improve the numerical models used for their design. In this study, the case of the RISOe-B1-18 airfoil which was equipped and measured in an open jet wind tunnel is studied. Two and three dimensional Navier-Stokes calculations using the k-w SST and Detached Eddy Simulation turbulence models are conducted. An engineering semi-empirical dynamic stall model is also used for performing calculations. Computational results are compared to the experimental results that are available both for the static airfoil and in the case of pitching motions. It is shown that the Navier-Stokes simulations can reproduced the main characteristic features of the flow. The DES model seems also to be able to reproduce some details of the unsteady aerodynamics. The Navier-Stokes computations can then be used to improve the performance of the engineering model. (au)

  16. Solar Equipment

    Science.gov (United States)

    1983-01-01

    A medical refrigeration and a water pump both powered by solar cells that convert sunlight directly into electricity are among the line of solar powered equipment manufactured by IUS (Independent Utility Systems) for use in areas where conventional power is not available. IUS benefited from NASA technology incorporated in the solar panel design and from assistance provided by Kerr Industrial Applications Center.

  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. Unsteady effects in flows past stationary airfoils with Gurney flaps due to unsteady flow separations at low Reynolds numbers

    Directory of Open Access Journals (Sweden)

    Dan MATEESCU

    2015-12-01

    Full Text Available This paper presents the analysis of the unsteady flows past stationary airfoils equipped with Gurney flaps at low Reynolds numbers, aiming to study the unsteady behavior of the aerodynamic coefficients due to the flow separations occurring at these Reynolds numbers. The Gurney flaps are simple but very efficient lift-increasing devices, which due to their mechanical simplicity are of particular interest for the small size micro-air-vehicles (MAV flying at low speed and very low Reynolds number. The unsteady aerodynamic analysis is performed with an efficient time-accurate numerical method developed for the solution of the Navier-Stokes equations at low Reynolds numbers, which is second-order-accurate in time and space. The paper presents solutions for the unsteady aerodynamic coefficients of lift and drag and for the lift-to-drag ratio of several symmetric and cambered airfoils with Gurney flaps. It was found that although the airfoil is considered stationary, starting from a relatively small incidence (about 8 degrees the flow becomes unsteady due to the unsteadiness of the flow separations occurring at low Reynolds numbers, and the aerodynamic coefficients display periodic oscillations in time. A detailed study is presented in the paper on the influence of various geometric and flow parameters, such as the Gurney flap height, Reynolds number, airfoil relative thickness and relative camber, on the aerodynamic coefficients of lift, drag and lift-to-drag ratio. The flow separation is also studied with the aid of flow visualizations illustrating the changes in the flow pattern at various moments in time.

  19. Influence of Thickness Variation on the Flapping Performance of Symmetric NACA Airfoils in Plunging Motion

    Directory of Open Access Journals (Sweden)

    Liangyu Zhao

    2010-01-01

    Full Text Available In order to investigate the impact of airfoil thickness on flapping performance, the unsteady flow fields of a family of airfoils from an NACA0002 airfoil to an NACA0020 airfoil in a pure plunging motion and a series of altered NACA0012 airfoils in a pure plunging motion were simulated using computational fluid dynamics techniques. The “class function/shape function transformation“ parametric method was employed to decide the coordinates of these altered NACA0012 airfoils. Under specified plunging kinematics, it is observed that the increase of an airfoil thickness can reduce the leading edge vortex (LEV in strength and delay the LEV shedding. The increase of the maximum thickness can enhance the time-averaged thrust coefficient and the propulsive efficiency without lift reduction. As the maximum thickness location moves towards the leading edge, the airfoil obtains a larger time-averaged thrust coefficient and a higher propulsive efficiency without changing the lift coefficient.

  20. 40 CFR 46.225 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Equipment. 46.225 Section 46.225... After the Fellowship § 46.225 Equipment. (a) If EPA authorizes you to purchase equipment (see § 46.140(b)) and the equipment retains a fair market value of more than $5,000, you must request...

  1. 49 CFR 19.34 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Equipment. 19.34 Section 19.34 Transportation... Requirements Property Standards § 19.34 Equipment. (a) Title to equipment acquired by a recipient with Federal... use equipment acquired with Federal funds to provide services to non-Federal outside organizations...

  2. 14 CFR 25.1561 - Safety equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Safety equipment. 25.1561 Section 25.1561....1561 Safety equipment. (a) Each safety equipment control to be operated by the crew in emergency, such... other life saving equipment must be marked accordingly. (c) Stowage provisions for required...

  3. 14 CFR 27.1561 - Safety equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Safety equipment. 27.1561 Section 27.1561... Safety equipment. (a) Each safety equipment control to be operated by the crew in emergency, such as... saving equipment, must be so marked....

  4. 30 CFR 56.7002 - Equipment defects.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Equipment defects. 56.7002 Section 56.7002... Piercing Drilling § 56.7002 Equipment defects. Equipment defects affecting safety shall be corrected before the equipment is used....

  5. 32 CFR 32.34 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 false Equipment. 32.34 Section 32.34 National Defense... ORGANIZATIONS Post-Award Requirements Property Standards § 32.34 Equipment. (a) Title to equipment acquired by a... recipient shall not use equipment acquired with Federal funds to provide services to non-Federal...

  6. 10 CFR 600.134 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Equipment. 600.134 Section 600.134 Energy DEPARTMENT OF... Nonprofit Organizations Post-Award Requirements § 600.134 Equipment. (a) Title to equipment acquired by a... recipient shall not use equipment acquired with Federal funds to provide services to non-Federal...

  7. 27 CFR 19.272 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Equipment. 19.272 Section... THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Construction, Equipment and Security § 19.272 Equipment. The proprietor shall provide equipment suitable for the operations conducted on the distilled...

  8. 14 CFR 27.1307 - Miscellaneous equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Miscellaneous equipment. 27.1307 Section 27... AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment General § 27.1307 Miscellaneous equipment. The following is the required miscellaneous equipment: (a) An approved seat for each occupant. (b) An...

  9. 15 CFR 14.34 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Equipment. 14.34 Section 14.34... ORGANIZATIONS Post-Award Requirements Property Standards § 14.34 Equipment. (a) Title to equipment acquired by a... recipient shall not use equipment acquired with Federal funds to provide services to non-Federal...

  10. 14 CFR 23.1561 - Safety equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Safety equipment. 23.1561 Section 23.1561... Markings and Placards § 23.1561 Safety equipment. (a) Safety equipment must be plainly marked as to method of operation. (b) Stowage provisions for required safety equipment must be marked for the benefit...

  11. 22 CFR 518.34 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Equipment. 518.34 Section 518.34 Foreign... Property Standards § 518.34 Equipment. (a) Title to equipment acquired by a recipient with Federal funds... equipment acquired with Federal funds to provide services to non-Federal outside organizations for a...

  12. 20 CFR 435.34 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Equipment. 435.34 Section 435.34 Employees...-Award Requirements Property Standards § 435.34 Equipment. (a) Title to equipment acquired by a recipient... may not use equipment acquired with Federal funds to provide services to non-Federal...

  13. 14 CFR 29.1307 - Miscellaneous equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Miscellaneous equipment. 29.1307 Section 29... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment General § 29.1307 Miscellaneous equipment. The following is required miscellaneous equipment: (a) An approved seat for each occupant. (b) A master...

  14. 14 CFR 23.1431 - Electronic equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Electronic equipment. 23.1431 Section 23... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 23.1431 Electronic equipment. (a) In showing compliance with § 23.1309(b)(1) and (2)...

  15. 14 CFR 25.1307 - Miscellaneous equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Miscellaneous equipment. 25.1307 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment General § 25.1307 Miscellaneous equipment. The following is required miscellaneous equipment: (a) (b) Two or more independent sources of electrical...

  16. 14 CFR 25.1431 - Electronic equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Electronic equipment. 25.1431 Section 25... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 25.1431 Electronic equipment. (a) In showing compliance with § 25.1309 (a) and (b) with respect to radio and...

  17. 14 CFR 23.1307 - Miscellaneous equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Miscellaneous equipment. 23.1307 Section 23... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Equipment General § 23.1307 Miscellaneous equipment. The equipment necessary for an airplane to operate at the maximum operating...

  18. 45 CFR 2543.34 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Equipment. 2543.34 Section 2543.34 Public Welfare... Requirements Property Standards § 2543.34 Equipment. (a) Title to equipment acquired by a recipient with... not use equipment acquired with Federal funds to provide services to non-Federal outside...

  19. 29 CFR 1926.600 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Equipment. 1926.600 Section 1926.600 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Motor Vehicles, Mechanized Equipment, and Marine Operations § 1926.600 Equipment. (a) General requirements. (1) All equipment left unattended at...

  20. 30 CFR 57.7002 - Equipment defects.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Equipment defects. 57.7002 Section 57.7002... Jet Piercing Drilling-Surface Only § 57.7002 Equipment defects. Equipment defects affecting safety shall be corrected before the equipment is used....

  1. 21 CFR 225.130 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Equipment. 225.130 Section 225.130 Food and Drugs... CURRENT GOOD MANUFACTURING PRACTICE FOR MEDICATED FEEDS Facilities and Equipment § 225.130 Equipment. Equipment shall be capable of producing a medicated feed of intended potency and purity, and shall...

  2. 28 CFR 70.34 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Equipment. 70.34 Section 70.34 Judicial... Post-Award Requirements Property Standards § 70.34 Equipment. (a) Title to equipment acquired by a... recipient must not use equipment acquired with Federal funds to provide services to non-Federal...

  3. 34 CFR 300.14 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Equipment. 300.14 Section 300.14 Education Regulations... DISABILITIES General Definitions Used in This Part § 300.14 Equipment. Equipment means— (a) Machinery, utilities, and built-in equipment, and any necessary enclosures or structures to house the...

  4. 40 CFR 160.61 - Equipment design.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Equipment design. 160.61 Section 160... LABORATORY PRACTICE STANDARDS Equipment § 160.61 Equipment design. Equipment used in the generation... appropriate design and adequate capacity to function according to the protocol and shall be suitably...

  5. 40 CFR 792.61 - Equipment design.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 31 2010-07-01 2010-07-01 true Equipment design. 792.61 Section 792.61...) GOOD LABORATORY PRACTICE STANDARDS Equipment § 792.61 Equipment design. Equipment used in the... of appropriate design and adequate capacity to function according to the protocol and shall...

  6. 21 CFR 58.61 - Equipment design.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Equipment design. 58.61 Section 58.61 Food and... PRACTICE FOR NONCLINICAL LABORATORY STUDIES Equipment § 58.61 Equipment design. Equipment used in the... of appropriate design and adequate capacity to function according to the protocol and shall...

  7. Aero-elastic stability of airfoil flow using 2-D CFD

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, J. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    A three degrees-of-freedom structural dynamics model has been coupled to a two-dimensional incompressible CFD code. The numerical investigation considers aero-elastic stability for two different airfoils; the NACA0012 and the LM 2 18 % airfoils. Stable and unstable configurations and limit cycle oscillations are predicted in accordance with literature for the first airfoil. An attempt to predict stall induced edge-wise vibrations on a wind turbine airfoil fails using this two-dimensional approach. (au)

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

    OpenAIRE

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

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-15

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

  10. Energy Harvesting of a Flapping Airfoil in a Vortical Wake

    Science.gov (United States)

    Zheng, Z. Charlie; Wei, Zhenglun

    2014-11-01

    We study the response of a two-dimensional flapping airfoil in the wake downstream of an oscillating D-shape cylinder. The airfoil has either heaving or pitching motions. The leading edge vortex (LEV) and trailing edge vortex (TEV) of the airfoil play important roles in energy harvesting. Two major interaction modes between the airfoil and incoming vortices, the suppressing mode and the reinforcing mode, are identified. However, distinctions exist between the heaving and pitching motion in terms of their contributions to the interaction modes and the efficiency of the energy extraction. A potential theory and the related fluid dynamics analysis are developed to analytically demonstrate that the topology of the incoming vortices corresponding to the airfoil is the primary factor that determines the interaction modes. Finally, the trade-off between the input and the output is discussed. It is found that appropriate operational parameters for the heaving motion are preferable in order to preserve acceptable input power for energy harvesters, while appropriate parameters for the pitching motion are essential to achieve decent output power.

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

    Directory of Open Access Journals (Sweden)

    D. M. Kercher

    2000-01-01

    Full Text Available 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 this airfoil region. Optimum cooling air requirements in this harsh environment has prompted a significant number of film cooling investigations and analytical studies reported over the past 25 years from academia, industry and government agencies. Substantial progress has been made in understanding the complex nature of leading edge film cooling from airfoil cascades, simulated airfoil leading edges and environment. This bibliography is a report of the open-literature references available which provide information on the complex aero–thermo interaction of leading edge gaseous film cooling with mainstream flow. From much of this investigative information has come successful operational leading edge film cooling design systems capable of sustaining airfoil leading edge durability in very hostile turbine environments.

  12. Design analysis of vertical wind turbine with airfoil variation

    Science.gov (United States)

    Maulana, Muhammad Ilham; Qaedy, T. Masykur Al; Nawawi, Muhammad

    2016-03-01

    With an ever increasing electrical energy crisis occurring in the Banda Aceh City, it will be important to investigate alternative methods of generating power in ways different than fossil fuels. In fact, one of the biggest sources of energy in Aceh is wind energy. It can be harnessed not only by big corporations but also by individuals using Vertical Axis Wind Turbines (VAWT). This paper presents a three-dimensional CFD analysis of the influence of airfoil design on performance of a Darrieus-type vertical-axis wind turbine (VAWT). The main objective of this paper is to develop an airfoil design for NACA 63-series vertical axis wind turbine, for average wind velocity 2,5 m/s. To utilize both lift and drag force, some of designs of airfoil are analyzed using a commercial computational fluid dynamics solver such us Fluent. Simulation is performed for this airfoil at different angles of attach rearranging from -12°, -8°, -4°, 0°, 4°, 8°, and 12°. The analysis showed that the significant enhancement in value of lift coefficient for airfoil NACA 63-series is occurred for NACA 63-412.

  13. Uncertainty Analysis for a Jet Flap Airfoil

    Science.gov (United States)

    Green, Lawrence L.; Cruz, Josue

    2006-01-01

    An analysis of variance (ANOVA) study was performed to quantify the potential uncertainties of lift and pitching moment coefficient calculations from a computational fluid dynamics code, relative to an experiment, for a jet flap airfoil configuration. Uncertainties due to a number of factors including grid density, angle of attack and jet flap blowing coefficient were examined. The ANOVA software produced a numerical model of the input coefficient data, as functions of the selected factors, to a user-specified order (linear, 2-factor interference, quadratic, or cubic). Residuals between the model and actual data were also produced at each of the input conditions, and uncertainty confidence intervals (in the form of Least Significant Differences or LSD) for experimental, computational, and combined experimental / computational data sets were computed. The LSD bars indicate the smallest resolvable differences in the functional values (lift or pitching moment coefficient) attributable solely to changes in independent variable, given just the input data points from selected data sets. The software also provided a collection of diagnostics which evaluate the suitability of the input data set for use within the ANOVA process, and which examine the behavior of the resultant data, possibly suggesting transformations which should be applied to the data to reduce the LSD. The results illustrate some of the key features of, and results from, the uncertainty analysis studies, including the use of both numerical (continuous) and categorical (discrete) factors, the effects of the number and range of the input data points, and the effects of the number of factors considered simultaneously.

  14. Prediction of the wind turbine performance by using BEM with airfoil data extracted from CFD

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Xu, Haoran;

    2014-01-01

    Blade element momentum (BEM) theory with airfoil data is a widely used technique for prediction of wind turbine aerodynamic performance, but the reliability of the airfoil data is an important factor for the prediction accuracy of aerodynamic loads and power. The airfoil characteristics used in BEM...

  15. 20 CFR 437.32 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Equipment. 437.32 Section 437.32 Employees... Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in the grantee or...

  16. 32 CFR 33.32 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 false Equipment. 33.32 Section 33.32 National Defense... Requirements Changes, Property, and Subawards § 33.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest...

  17. 10 CFR 600.232 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Equipment. 600.232 Section 600.232 Energy DEPARTMENT OF... Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in the grantee or...

  18. 38 CFR 43.32 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Equipment. 43.32 Section... Requirements Changes, Property, and Subawards § 43.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest...

  19. 40 CFR 31.32 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Equipment. 31.32 Section 31.32... Requirements Changes, Property, and Subawards § 31.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest...

  20. 29 CFR 1470.32 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Equipment. 1470.32 Section 1470.32 Labor Regulations... Changes, Property, and Subawards § 1470.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest...

  1. 36 CFR 1207.32 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Equipment. 1207.32 Section... Post-Award Requirements Changes, Property, and Subawards § 1207.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or...

  2. 45 CFR 2541.320 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 4 2010-10-01 2010-10-01 false Equipment. 2541.320 Section 2541.320 Public... Changes, Property and Subawards § 2541.320 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest...

  3. 14 CFR 1273.32 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Equipment. 1273.32 Section 1273.32..., Property, and Subawards § 1273.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition...

  4. 21 CFR 1403.32 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Equipment. 1403.32 Section 1403.32 Food and Drugs... Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in the grantee or...

  5. 22 CFR 135.32 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Equipment. 135.32 Section 135.32 Foreign... Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in the grantee or...

  6. 24 CFR 85.32 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Equipment. 85.32 Section 85.32... TRIBAL GOVERNMENTS Post-Award Requirements Changes, Property, and Subawards § 85.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under...

  7. 15 CFR 24.32 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Equipment. 24.32 Section 24.32..., Property, and Subawards § 24.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition...

  8. 29 CFR 97.32 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Equipment. 97.32 Section 97.32 Labor Office of the Secretary... GOVERNMENTS Post-Award Requirements Changes, Property, and Subawards § 97.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant...

  9. 45 CFR 92.32 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Equipment. 92.32 Section 92.32 Public Welfare..., Property, and Subawards § 92.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition...

  10. 29 CFR 1926.1090 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Equipment. 1926.1090 Section 1926.1090 Labor Regulations...) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Diving Equipment Procedures and Requirements § 1926.1090 Equipment. Note: The requirements applicable to construction work under this section are identical to...

  11. 45 CFR 602.32 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Equipment. 602.32 Section 602.32 Public Welfare....32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in the grantee...

  12. 45 CFR 1157.32 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Equipment. 1157.32 Section 1157.32 Public Welfare... AND LOCAL GOVERNMENTS Post-Award Requirements Changes, Property, and Subawards § 1157.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment...

  13. 45 CFR 1183.32 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Equipment. 1183.32 Section 1183.32 Public Welfare... Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in the grantee or...

  14. 44 CFR 13.32 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Equipment. 13.32 Section 13... LOCAL GOVERNMENTS Post-Award Requirements Changes, Property, and Subawards § 13.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under...

  15. 7 CFR 3016.32 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Equipment. 3016.32 Section 3016.32 Agriculture... GOVERNMENTS Post-Award Requirements Changes, Property, and Subawards § 3016.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under...

  16. 43 CFR 12.72 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Equipment. 12.72 Section 12.72 Public... to State and Local Governments Changes, Property, and Subawards § 12.72 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under...

  17. 49 CFR 18.32 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Equipment. 18.32 Section 18.32 Transportation... Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in the grantee or...

  18. 13 CFR 143.32 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Equipment. 143.32 Section 143.32..., and Subawards § 143.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or subgrant will vest upon acquisition in...

  19. Study on optimal design of wind turbine blade airfoil and its application

    International Nuclear Information System (INIS)

    This study was carried out with two goals. One was the development of a model of a wind turbine blade airfoil and the other was the application of the folding blade. In general, in large sized (MW) wind turbines, damage is prevented in small wind turbines since equipment costs and maintenance costs are high, and therefore, the blade will cause serious damage. The wind turbine proposed in this study does not require maintenance, and the blades do not break during high winds because they are folded in accordance with changes in the wind speed. But generators are not cut out, while maintaining a constant angle will continue to produce. The focus of this study, the wind turbine is continued by folding blade system in strong winds and gusts without stopping production

  20. Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency

    Directory of Open Access Journals (Sweden)

    I. H. Tuncer

    2004-01-01

    Full Text Available A numerical optimization algorithm based on the steepest decent along the variation of the optimization function is implemented for maximizing the thrust and/or propulsive efficiency of a single flapping airfoil. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver on moving overset grids. The flapping motion of the airfoil is described by a combined sinusoidal plunge and pitching motion. Optimization parameters are taken to be the amplitudes of the plunge and pitching motions, and the phase shift between them. Computations are performed in parallel in a work station cluster. The numerical simulations show that high thrust values may be obtained at the expense of reduced efficiency. For high efficiency in thrust generation, the induced angle of attack of the airfoil is reduced and large scale vortex formations at the leading edge are prevented. 

  1. CFD Analysis on Airfoil at High Angles of Attack

    Directory of Open Access Journals (Sweden)

    Dr.P.PrabhakaraRao, Sri Sampath.V

    2014-07-01

    Full Text Available The present work describes a conceptual study of performance enhancing devices for an airfoil by using Computational Fluid Dynamics. Two simple passive devices are selected and examined for Lift improvement and for decrease in Drag. The motivation behind this project is to study these effective techniques to improve performance with fewer drawbacks then previously existing model. The effective position for the location of Dimples and Cylinder are found out. Among the two selected models, Dimple model shows good results compare to other. The CAD model is prepared in CATIA V5 R19, pre-processing is done in ANSYS ICEM CFD 14.0 and simulations are carried out in ANSYS FLUENT 14.0. The overall aim of the project is to improve airfoil performance at high angle-of-attack. The results justify the optimum position for placing Dimple and cylinder for enhancing airfoil performance.

  2. Vortex scale of unsteady separation on a pitching airfoil.

    Science.gov (United States)

    Fuchiwaki, Masaki; Tanaka, Kazuhiro

    2002-10-01

    The streaklines of unsteady separation on two kinds of pitching airfoils, the NACA65-0910 and a blunt trailing edge airfoil, were studied by dye flow visualization and by the Schlieren method. The latter visualized the discrete vortices shed from the leading edge. The results of these visualization studies allow a comparison between the dynamic behavior of the streakline of unsteady separation and that of the discrete vortices shed from the leading edge. The influence of the airfoil configuration on the flow characteristics was also examined. Furthermore, the scale of a discrete vortex forming the recirculation region was investigated. The non-dimensional pitching rate was k = 0.377, the angle of attack alpha(m) = 16 degrees and the pitching amplitude was fixed to A = +/-6 degrees for Re = 4.0 x 10(3) in this experiment. PMID:12495998

  3. Automated CFD for Generation of Airfoil Performance Tables

    Science.gov (United States)

    Strawn, Roger; Mayda, E. Q.; vamDam, C. P.

    2009-01-01

    A method of automated computational fluid dynamics (CFD) has been invented for the generation of performance tables for an object subject to fluid flow. The method is applicable to the generation of tables that summarize the effects of two-dimensional flows about airfoils and that are in a format known in the art as C81. (A C81 airfoil performance table is a text file that lists coefficients of lift, drag, and pitching moment of an airfoil as functions of angle of attack for a range of Mach numbers.) The method makes it possible to efficiently generate and tabulate data from simulations of flows for parameter values spanning all operational ranges of actual or potential interest. In so doing, the method also enables filling of gaps and resolution of inconsistencies in C81 tables generated previously from incomplete experimental data or from theoretical calculations that involved questionable assumptions.

  4. Response of a thin airfoil encountering strong density discontinuity

    Energy Technology Data Exchange (ETDEWEB)

    Marble, F.E. [California Inst. of Tech., Pasadena, CA (United States). Karman Lab. of Fluid Mechanics

    1993-12-01

    Airfoil theory for unsteady motion has been developed extensively assuming the undisturbed medium to be of uniform density, a restriction accurate for motion in the atmosphere. In some instances, notably for airfoil comprising fan, compressor and turbine blade rows, the undisturbed medium may carry density variations or ``spots``, resulting from non-uniformities in temperature or composition, of a size comparable to the blade chord. This condition exists for turbine blades, immediately downstream of the main burner of a gas turbine engine where the density fluctuations of the order of 50 percent may occur. Disturbances of a somewhat smaller magnitude arise from the ingestion of hot boundary layers into fans, and exhaust into hovercraft. Because these regions of non-uniform density convect with the moving medium, the airfoil experiences a time varying load and moment which the authors calculate.

  5. Aerodynamic performance of an annular classical airfoil cascade

    Science.gov (United States)

    Bergsten, D. E.; Stauter, R. C.; Fleeter, S.

    1983-01-01

    Results are presented for a series of experiments that were performed in a large-scale subsonic annular cascade facility that was specifically designed to provide three-dimensional aerodynamic data for the verification of numerical-calculation codes. In particular, the detailed three-dimensional aerodynamic performance of a classical flat-plate airfoil cascade is determined for angles of incidence of 0, 5, and 10 deg. The resulting data are analyzed and are correlated with predictions obtained from NASA's MERIDL and TSONIC numerical programs. It is found that: (1) at 0 and 5 deg, the airfoil surface data show a good correlation with the predictions; (2) at 10 deg, the data are in fair agreement with the numerical predictions; and (3) the two-dimensional Gaussian similarity relationship is appropriate for the wake velocity profiles in the mid-span region of the airfoil.

  6. Contribution to finite element modelling of airfoil aeroelastic instabilities

    Directory of Open Access Journals (Sweden)

    Horáček J.

    2007-10-01

    Full Text Available Nonlinear equations of motion for a flexibly supported rigid airfoil with additional degree of freedom for controlling of the profile motion by a trailing edge flap are derived for large vibration amplitudes. Preliminary results for numerical simulation of flow-induced airfoil vibrations in a laminar incompressible flow are presented for the NACA profile 0012 with three-degrees of freedom (vertical translation, rotation around the elastic axis and rotation of the flap. The developed numerical solution of the Navier – Stokes equations and the Arbitrary Eulerian-Lagrangian approach enable to consider the moving grid for the finite element modelling of the fluid flow around the oscillating airfoil. A sequence of numerical simulation examples is presented for Reynolds numbers up to about Re~10^5, when the system loses the aeroelastic stability, and when the large displacements of the profile and a post-critical behaviour of the system take place.

  7. Multi-objective optimization design of airfoil and wing

    Institute of Scientific and Technical Information of China (English)

    ZHU; Ziqiang; FU; Hongyan; YU; Rixin; LIU; Jie

    2004-01-01

    To extend available monoobjective optimization methods to multiobjective and multidisciplinary optimization, the construction of a suitable resultant objective function(in deterministic method-DM) or a fitness function(in genetic algorithm-GA) is important. An objective function combination method (OFCM) of constructing such a function for constrained optimization problems is suggested. How to use both deterministic and genetic algorithms to biobjective and bidisciplinary optimal design of high performance airfoils and wings is discussed. Numerical results in both 2D (airfoil) and 3D (wing) cases show that the present method can be used to optimaize different kinds of initial airfoils and wings. The performance of optimized shape is improved significantly. The method is successful and effective.

  8. Analysis of jet-airfoil interaction noise sources by using a microphone array technique

    Science.gov (United States)

    Fleury, Vincent; Davy, Renaud

    2016-03-01

    The paper is concerned with the characterization of jet noise sources and jet-airfoil interaction sources by using microphone array data. The measurements were carried-out in the anechoic open test section wind tunnel of Onera, Cepra19. The microphone array technique relies on the convected, Lighthill's and Ffowcs-Williams and Hawkings' acoustic analogy equation. The cross-spectrum of the source term of the analogy equation is sought. It is defined as the optimal solution to a minimal error equation using the measured microphone cross-spectra as reference. This inverse problem is ill-posed yet. A penalty term based on a localization operator is therefore added to improve the recovery of jet noise sources. The analysis of isolated jet noise data in subsonic regime shows the contribution of the conventional mixing noise source in the low frequency range, as expected, and of uniformly distributed, uncorrelated noise sources in the jet flow at higher frequencies. In underexpanded supersonic regime, a shock-associated noise source is clearly identified, too. An additional source is detected in the vicinity of the nozzle exit both in supersonic and subsonic regimes. In the presence of the airfoil, the distribution of the noise sources is deeply modified. In particular, a strong noise source is localized on the flap. For high Strouhal numbers, higher than about 2 (based on the jet mixing velocity and diameter), a significant contribution from the shear-layer near the flap is observed, too. Indications of acoustic reflections on the airfoil are also discerned.

  9. Research on design methods and aerodynamics performance of CQUDTU-B21 airfoil

    DEFF Research Database (Denmark)

    Chen, Jin; Cheng, Jiangtao; Wen, Zhong Shen

    This paper presents the design methods of CQU-DTU-B21 airfoil for wind turbine. Compared with the traditional method of inverse design, the new method is described directly by a compound objective function to balance several conflicting requirements for design wind turbine airfoils, which based on...... design theory of airfoil profiles, blade element momentum (BEM) theory and airfoil Self-Noise prediction model. And then an optimization model with the target of maximum power performance on a 2D airfoil and low noise emission of design ranges for angle of attack has been developed for designing CQU...

  10. 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)

  11. CFD Analysis of Circulation Control Airfoils Using Fluent

    Science.gov (United States)

    McGowan, Gregory; Gopalarathnam, Ashok

    2005-01-01

    In an effort to validate computational fluid dynamics procedures for calculating flows around circulation control airfoils, the commercial flow solver FLUENT was utilized to study the flow around a general aviation circulation control airfoil. The results were compared to experimental and computational fluid dynamics results conducted at the NASA Langley Research Center. The current effort was conducted in three stages: 1. A comparison of the results for free-air conditions to those from experiments. 2. A study of wind-tunnel wall effects. and 3. A study of the stagnation-point behavior.

  12. Unsteady Double Wake Model for the Simulation of Stalled Airfoils

    DEFF Research Database (Denmark)

    Ramos García, Néstor; Cayron, Antoine; Sørensen, Jens Nørkær

    2015-01-01

    In the present work, the recent developed Unsteady Double Wake Model, USDWM, is used to simulate separated flows past a wind turbine airfoil at high angles of attack. The solver is basically an unsteady two-dimensional panel method which uses the unsteady double wake technique to model flow...... separation and its dynamics. In this paper, the calculated integral forces have been successfully validated against wind tunnel measurements for the FFA-W3-211 airfoil. Furthermore, the computed highly unsteady flow field is analyzed in detail for a set of angles of attack ranging from light to deep stall...

  13. Detached Eddy Simulations of an Airfoil in Turbulent Inflow

    DEFF Research Database (Denmark)

    Gilling, Lasse; Sørensen, Niels; Davidson, Lars

    2009-01-01

    The effect of resolving inflow turbulence in detached eddy simulations of airfoil flows is studied. Synthetic turbulence is used for inflow boundary condition. The generated turbulence fields are shown to decay according to experimental data as they are convected through the domain with the free...... stream velocity. The subsonic flow around a NACA 0015 airfoil is studied at Reynolds number 1.6 × 106 and at various angles of attack before and after stall. Simulations with turbulent inflow are compared to experiments and to simulations without turbulent inflow. The results show that the flow is...

  14. 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....

  15. 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...

  16. Extraction of airfoil data using PIV and pressure measurements

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær;

    2011-01-01

    A newly developed technique for determining the angle of attack (AOA) on a rotating blade is used to extract AOAs and airfoil data from measurements obtained during the MEXICO (Model rotor EXperiments in COntrolled conditions) rotor experiment. Detailed surface pressure and Particle Image...... of the rotor. The extraction technique is verified by employing the derived airfoil characteristics as input to computations using the BEM technique and comparing the calculated axial and tangential forces to the measured data. The comparison also demonstrates that the used technique of determining...

  17. Wake instability issues: From circular cylinders to stalled airfoils

    Science.gov (United States)

    Meneghini, J. R.; Carmo, B. S.; Tsiloufas, S. P.; Gioria, R. S.; Aranha, J. A. P.

    2011-07-01

    Some recent results regarding the global dynamical behaviour of the wake of circular cylinders and airfoils with massive separation are reviewed in this paper. In order to investigate the effect of interference, the three-dimensional instability modes are analysed for the flow around two circular cylinders in tandem. In the same way, the flow around a stalled airfoil is investigated in order to provide a better understanding of the three-dimensional characteristics of wakes forming downstream of a lifting body with massive separation. These results are compared with those found for an isolated cylinder. Some fundamental differences among these flows are discussed.

  18. Design of wind turbine airfoils based on maximum power coefficient

    DEFF Research Database (Denmark)

    Chen, Jin; Cheng, Jiangtao; Shen, Wenzhong;

    2010-01-01

    noise prediction model, the previously developed integrated design technique is further developed. The new code takes into account different airfoil requirements according to their local positions on a blade, such as sensitivity to leading edge roughness, design lift at off-design condition, stall......Based on the blade element momentum (BEM) theory, the power coefficient of a wind turbine can be expressed in function of local tip speed ratio and lift-drag ratio. By taking the power coefficient in a predefined range of angle of attack as the final design objective and combining with an airfoil...

  19. Aspects of Numerical Simulation of Circulation Control Airfoils

    Science.gov (United States)

    Swanson, R. C.; Rumsey, C. L.; Anders, S. G.

    2005-01-01

    The mass-averaged compressible Navier-Stokes equations are solved for circulation control airfoils. Numerical solutions are computed with a multigrid method that uses an implicit approximate factorization smoother. The effects of flow conditions (e.g., free-stream Mach number, angle of attack, momentum coefficient) and mesh on the prediction of circulation control airfoil flows are considered. In addition, the impact of turbulence modeling, including curvature effects and modifications to reduce eddy viscosity levels in the wall jet (i.e., Coanda flow), is discussed. Computed pressure distributions are compared with available experimental data.

  20. Aerodynamic shape optimization for alleviating dynamic stall characteristics of helicopter rotor airfoil

    Directory of Open Access Journals (Sweden)

    Wang Qing

    2015-04-01

    Full Text Available In order to alleviate the dynamic stall effects in helicopter rotor, the sequential quadratic programming (SQP method is employed to optimize the characteristics of airfoil under dynamic stall conditions based on the SC1095 airfoil. The geometry of airfoil is parameterized by the class-shape-transformation (CST method, and the C-topology body-fitted mesh is then automatically generated around the airfoil by solving the Poisson equations. Based on the grid generation technology, the unsteady Reynolds-averaged Navier-Stokes (RANS equations are chosen as the governing equations for predicting airfoil flow field and the highly-efficient implicit scheme of lower–upper symmetric Gauss–Seidel (LU-SGS is adopted for temporal discretization. To capture the dynamic stall phenomenon of the rotor more accurately, the Spalart–Allmaras turbulence model is employed to close the RANS equations. The optimized airfoil with a larger leading edge radius and camber is obtained. The leading edge vortex and trailing edge separation of the optimized airfoil under unsteady conditions are obviously weakened, and the dynamic stall characteristics of optimized airfoil at different Mach numbers, reduced frequencies and angles of attack are also obviously improved compared with the baseline SC1095 airfoil. It is demonstrated that the optimized method is effective and the optimized airfoil is suitable as the helicopter rotor airfoil.

  1. Design and validation of the high performance and low noise CQU-DTU-LN1 airfoils

    DEFF Research Database (Denmark)

    Cheng, Jiangtao; Zhu, Wei Jun; Fischer, Andreas;

    2014-01-01

    This paper presents the design and validation of the high performance and low noise Chong Qing University and Technical University of Denmark LN1 (CQU-DTU-LN1) series of airfoils for wind turbine applications. The new design method uses target characteristics of wind turbine airfoils in the design...... objective, such as airfoil lift coefficient, drag coefficient and lift-drag ratio, and minimizes trailing edge noise as a constraint. To express airfoil shape, an analytical expression is used. One of the main advantages of the present designmethod is that it produces a highly smooth airfoil shape that can...... blade element momentum theory, the viscous-inviscid XFOIL code and an airfoil self-noise prediction model, an optimization algorithm has been developed for designing the high performance and low noise CQU-DTU-LN1 series of airfoils with targets of maximum power coefficient and low noise emission. To...

  2. Design of the new Risoe-A1 airfoil family for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Fuglsang, P.; Dahl, K.S. [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark)

    1999-03-01

    A new airfoil family for wind turbines was developed by use of a design method using numerical optimization and the flow solver, XFOIL. The results were evaluated with the Navier-Stokes solver EllipSys2D. The airfoil family constitutes 6 airfoils ranging in thickness from 15% to 30%. The airfoils were designed to have a maximum lift coefficient around 1.5 in natural conditions and high lift-drag ratios below maximum lift. Insensitivity to leading edge roughness was obtained by securing that transition from laminar to turbulent flow on the suction side occurred close to the leading edge just before stall. The airfoil family was designed for a 600 kW wind turbine and provides a basis for further enhancing the characteristics of airfoils for wind turbines and to tailor airfoils for specific rotor sizes and power regulation principles. (au) EFP-95; EFP-98. 16 refs.

  3. The effects of leading-edge serrations on reducing flow unsteadiness about airfoils, an experimental and analytical investigation

    Science.gov (United States)

    Schwind, R. G.; Allen, H. J.

    1973-01-01

    High frequency surface pressure measurements were obtained from wind-tunnel tests over the Reynolds number range 1.2 times one million to 6.2 times one million on a rectangular wing of NACA 63-009 airfoil section. Measurements were also obtained with a wide selection of leading-edge serrations added to the basic airfoil. Under a two-dimensional laminar bubble very close to the leading edge of the basic airfoil there is a large apatial peak in rms pressure. Frequency analysis of the pressure signals in this region show a large, high-frequency energy peak which is interpreted as an oscillation in size and position of the bubble. The serrations divide the bubble into segments and reduce the peak rms pressures. A low Reynolds number flow visualization test on a hydrofoil in water was also conducted. A von Karman vortex street was found trailing from the rear of the foil. Its frequency is at a much lower Strouhal number than in the high Reynolds number experiment, and is related to the trailing-edge and boundary-layer thicknesses.

  4. Preliminary wind-tunnel investigation of an NACA 23012 airfoil with various arrangements of venetian-blind flaps

    Science.gov (United States)

    Wenzinger, Carl J; Harris, Thomas A

    1940-01-01

    Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a large-chord NACA 23012 airfoil with several arrangements of venetian-blind flaps to determine the aerodynamic section characteristics as affected by the over-all flap chord, the chords of the slats used to form the flap, the slat spacing, the number of slats and the position of the flap with respect to the wing. Complete section data are given in the form of graphs for all the combinations tested.

  5. Airfoil Computations using the γ - Reθ Model

    DEFF Research Database (Denmark)

    Sørensen, Niels N.

    computations. Based on this, an estimate of the error in the computations is determined to be approximately one percent in the attached region. Following the verification of the implemented model, the model is applied to four airfoils, NACA64- 018, NACA64-218, NACA64-418 and NACA64-618 and the results are...

  6. Numerical Investigations of an Optimized Airfoil with a Rotary Cylinder

    Science.gov (United States)

    Gada, Komal; Rahai, Hamid

    2015-11-01

    Numerical Investigations of an optimized thin airfoil with a rotary cylinder as a control device for reducing separation and improving lift to drag ratio have been performed. Our previous investigations have used geometrical optimization for development of an optimized airfoil with increased torque for applications in a vertical axis wind turbine. The improved performance was due to contributions of lift to torque at low angles of attack. The current investigations have been focused on using the optimized airfoil for micro-uav applications with an active flow control device, a rotary cylinder, to further control flow separation, especially during wind gust conditions. The airfoil has a chord length of 19.66 cm and a width of 25 cm with 0.254 cm thickness. Previous investigations have shown flow separation at approximately 85% chord length at moderate angles of attack. Thus the rotary cylinder with a 0.254 cm diameter was placed slightly downstream of the location of flow separation. The free stream mean velocity was 10 m/sec. and investigations have been performed at different cylinder's rotations with corresponding tangential velocities higher than, equal to and less than the free stream velocity. Results have shown more than 10% improvement in lift to drag ratio when the tangential velocity is near the free stream mean velocity. Graduate Assistant, Center for Energy and Environmental Research and Services (CEERS), College of Engineering, California State University, Long Beach.

  7. Flow characteristics over NACA4412 airfoil at low Reynolds number

    Science.gov (United States)

    Genç, Mustafa Serdar; Koca, Kemal; Hakan Açıkel, Halil; Özkan, Gökhan; Sadık Kırış, Mehmet; Yıldız, Rahime

    2016-03-01

    In this study, the flow phenomena over NACA4412 were experimentally observed at various angle of attack and Reynolds number of 25000, 50000 and 75000, respectively. NACA4412 airfoil was manufactured at 3D printer and each tips of the wing were closed by using plexiglas to obtain two-dimensional airfoil. The experiments were conducted at low speed wind tunnel. The force measurement and hot-wire experiments were conducted to obtain data so that the flow phenomenon at the both top and bottom of the airfoil such as the flow separation and vortex shedding were observed. Also, smoke-wire experiment was carried out to visualize the surface flow pattern. After obtaining graphics from both force measurement experiment and hot-wire experiment compared with smoke wire experiment, it was noticed that there is a good coherence among the experiments. It was concluded that as Re number increased, the stall angle increased. And the separation bubble moved towards leading edge over the airfoil as the angle of attack increased.

  8. High frequency microphone measurements for transition detection on airfoils

    DEFF Research Database (Denmark)

    Døssing, Mads

    Time series of pressure fluctuations has been obtained using high frequency microphones distributed over the surface of airfoils undergoing wind tunnel tests in the LM Windtunnel, owned by ’LM Glasfiber’, Denmark. The present report describes the dataanalysis, with special attention given to...

  9. Experimental Investigation on Airfoil Shock Control by Plasma Aerodynamic Actuation

    International Nuclear Information System (INIS)

    An experimental investigation on airfoil (NACA64—215) shock control is performed by plasma aerodynamic actuation in a supersonic tunnel (Ma = 2). The results of schlieren and pressure measurement show that when plasma aerodynamic actuation is applied, the position moves forward and the intensity of shock at the head of the airfoil weakens. With the increase in actuating voltage, the total pressure measured at the head of the airfoil increases, which means that the shock intensity decreases and the control effect increases. The best actuation effect is caused by upwind-direction actuation with a magnetic field, and then downwind-direction actuation with a magnetic field, while the control effect of aerodynamic actuation without a magnetic field is the most inconspicuous. The mean intensity of the normal shock at the head of the airfoil is relatively decreased by 16.33%, and the normal shock intensity is relatively reduced by 27.5% when 1000 V actuating voltage and upwind-direction actuation are applied with a magnetic field. This paper theoretically analyzes the Joule heating effect generated by DC discharge and the Lorentz force effect caused by the magnetic field. The discharge characteristics are compared for all kinds of actuation conditions to reveal the mechanism of shock control by plasma aerodynamic actuation

  10. Large Eddy Simulations of an Airfoil in Turbulent Inflow

    DEFF Research Database (Denmark)

    Gilling, Lasse; Sørensen, Niels

    Wind turbines operate in the turbulent boundary layer of the atmosphere and due to the rotational sampling effect the blades experience a high level of turbulence [1]. In this project the effect of turbulence is investigated by large eddy simulations of the turbulent flow past a NACA 0015 airfoil...

  11. Flow characteristics over NACA4412 airfoil at low Reynolds number

    Directory of Open Access Journals (Sweden)

    Genç Mustafa Serdar

    2016-01-01

    Full Text Available In this study, the flow phenomena over NACA4412 were experimentally observed at various angle of attack and Reynolds number of 25000, 50000 and 75000, respectively. NACA4412 airfoil was manufactured at 3D printer and each tips of the wing were closed by using plexiglas to obtain two-dimensional airfoil. The experiments were conducted at low speed wind tunnel. The force measurement and hot-wire experiments were conducted to obtain data so that the flow phenomenon at the both top and bottom of the airfoil such as the flow separation and vortex shedding were observed. Also, smoke-wire experiment was carried out to visualize the surface flow pattern. After obtaining graphics from both force measurement experiment and hot-wire experiment compared with smoke wire experiment, it was noticed that there is a good coherence among the experiments. It was concluded that as Re number increased, the stall angle increased. And the separation bubble moved towards leading edge over the airfoil as the angle of attack increased.

  12. The Ultimate Flow Controlled Wind Turbine Blade Airfoil

    Science.gov (United States)

    Seifert, Avraham; Dolgopyat, Danny; Friedland, Ori; Shig, Lior

    2015-11-01

    Active flow control is being studied as an enabling technology to enhance and maintain high efficiency of wind turbine blades also with contaminated surface and unsteady winds as well as at off-design operating conditions. The study is focused on a 25% thick airfoil (DU91-W2-250) suitable for the mid blade radius location. Initially a clean airfoil was fabricated and tested, as well as compared to XFoil predictions. From these experiments, the evolution of the separation location was identified. Five locations for installing active flow control actuators are available on this airfoil. It uses both Piezo fluidic (``Synthetic jets'') and the Suction and Oscillatory Blowing (SaOB) actuators. Then we evaluate both actuation concepts overall energy efficiency and efficacy in controlling boundary layer separation. Since efficient actuation is to be found at low amplitudes when placed close to separation location, distributed actuation is used. Following the completion of the baseline studies the study has focused on the airfoil instrumentation and extensive wind tunnel testing over a Reynolds number range of 0.2 to 1.5 Million. Sample results will be presented and outline for continued study will be discussed.

  13. Mechanism of unconventional aerodynamic characteristics of an elliptic airfoil

    Directory of Open Access Journals (Sweden)

    Sun Wei

    2015-06-01

    Full Text Available The aerodynamic characteristics of elliptic airfoil are quite different from the case of conventional airfoil for Reynolds number varying from about 104 to 106. In order to reveal the fundamental mechanism, the unsteady flow around a stationary two-dimensional elliptic airfoil with 16% relative thickness has been simulated using unsteady Reynolds-averaged Navier–Stokes equations and the γ-Reθt‾ transition turbulence model at different angles of attack for flow Reynolds number of 5 × 105. The aerodynamic coefficients and the pressure distribution obtained by computation are in good agreement with experimental data, which indicates that the numerical method works well. Through this study, the mechanism of the unconventional aerodynamic characteristics of airfoil is analyzed and discussed based on the computational predictions coupled with the wind tunnel results. It is considered that the boundary layer transition at the leading edge and the unsteady flow separation vortices at the trailing edge are the causes of the case. Furthermore, a valuable insight into the physics of how the flow behavior affects the elliptic airfoil’s aerodynamics is provided.

  14. 29 CFR 1928.57 - Guarding of farm field equipment, farmstead equipment, and cotton gins.

    Science.gov (United States)

    2010-07-01

    ... cotton gins. 1928.57 Section 1928.57 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY..., farmstead equipment, and cotton gins. (a) General—(1) Purpose. The purpose of this section is to provide for... equipment, farmstead equipment, and cotton gins used in any agricultural operation. (2) Scope. Paragraph...

  15. Airfoil Selection for a Lift Type Vertical Axis Wind Turbine%升力型垂直轴风力机翼型的选择

    Institute of Scientific and Technical Information of China (English)

    孙晓晶; 陆启迪; 黄典贵; 吴国庆

    2012-01-01

    At present,there are many different types of airfoils that have been used in lift-type vertical axis wind turbines.In order to study the influence of different airfoils on the lift-type vertical axis wind turbine performance,two-dimensional numerical simulation of flow around a Darrieus-type straight-bladed vertical axis wind turbine was conducted in this paper with the aid of computational fluid dynamics software and sliding mesh method.Numerical results suggest that NACA0018 airfoil is the most suitable airfoil section used by a lift-type vertical axis wind turbine rotors as it can allow the wind turbine to achieve the highest wind energy utilization efficiency.%目前升力型垂直轴风力机采用的翼型多种多样,为了研究不同翼型对升力型垂直轴风力机风能利用率的影响,本文采用计算流体力学软件和滑移网格技术对升力型直叶片垂直轴风力机进行二维流场的数值模拟。结果表明,对于升力型垂直轴风力机,当选择NACA0018翼型可以达到最高的风能利用率。

  16. A comparison of two-and three-dimensional S809 airfoil properties for rough and smooth HAWT (Horizontal-Axis Wind Tunnel) rotor operation

    Science.gov (United States)

    Musial, W. D.; Butterfield, C. P.; Jenks, M. D.

    1990-02-01

    At the Solar Energy Research Institute (SERI), we carried out tests to measure the effects of leading-edge roughness on an S809 airfoil using a 10-m, three-bladed, horizontal-axis wind turbine (HAWT). The rotor employed a constant-chord (.457 m) blade geometry with zero twist. Blade structural loads were measured with strain gages mounted at 9 spanwise locations. Airfoil pressure measurements were taken at the 80 percent spanwise station using 32 pressure taps distributed around the airfoil surface. Detailed inflow measurements were taken using nine R.M. Young Model 8002 propvane anemometers on a vertical plane array (VPA) located 10 m upwind of the test turbine in the prevailing wind direction. The major objective of this test was to determine the sensitivity of the S809 airfoil to roughness on a rotating wind turbine blade. We examined this effect by comparing several parameters. We compared power curves to show the sensitivity of whole rotor performance to roughness. We used pressure measurements to generate pressure distributions at the 80 percent span which operates at a Reynolds number (Re) of 800,000. We then integrated these distributions to determine the effect of roughness on the section's lift and pressure-drag coefficients.

  17. Robust Airfoil Optimization with Multi-objective Estimation of Distribution Algorithm

    Institute of Scientific and Technical Information of China (English)

    Zhong Xiaoping; Ding Jifeng; Li Weiji; Zhang Yong

    2008-01-01

    A transonic airfoil designed by means of classical point-optimization may result in its dramatically inferior performance under off-design conditious. To overcome this shortcoming, robust design is proposed to fred out the optimal profile of an airfoil to maintain its performance in an uncertain environment. The robust airfoil optimization is aimed to minimize mean values and variances of drag coefficients while satisfying the lift and thickness constraints over a range of Maeb numbers. A multi-objective estimation of distribution algorithm is applied to the robust airfoil optimization on the base of the RAE2822 benchmark airfoil. The shape of the airfoil is obtained through superposing ten Hick-Heune shape functions upon the benchmark airfoil. A set of design points is selected according to a uniform design table for aerodynamic evaluation. A Kriging model of drag coefficient is coustrueted with those points to reduce eumputing costs. Over the Maeh range fi'om 0.7 to 0.8, the airfoil generated by the robust optimization has a configuration characterized by supercritical airfoil with low drag coefficients. The small fluctuation in its drag coefficients means that the performance of the robust airfoil is insensitive to variation of Mach number.

  18. Test results of NREL 10M, special-purpose family of thin airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Starcher, K.L.; Nelson, V.C.; Wei, Jun [West Texas A& M Univ., Canyon, TX (United States)

    1996-12-31

    Two 25 kW Carter Wind Systems were tested to determine performance differences between production blades and rotors with NREL Special Purpose Thin Airfoils. Blade design, mold preparation, blade production, and testing were conducted. Design tools were created for computer modeling of the blade. The blades had the same twist, taper, and length as production blades. Flap natural frequency was adjusted to be as similar as possible between rotors, as was blade mass, blade center of gravity and rotor moment of inertia. Data collected were; wind speed at hub height, blade root flap & edgewise loads, main shaft torque, azimuth position, teeter angle, yaw angle and electrical power. These data were collected at 128 Hertz for data sets of eight seconds. This data set was then written to hard disk and the cycle repeated resulting in a file containing five and one half minutes of data. A data run consisted of; preflight checkout/warm-up of equipment, preflight calibration/verification of all sensors on both turbines, collection of five files of data (about thirty minutes of data), post flight calibration/verification of sensors. During this high speed data collection period there were a total of twenty-four data runs collected. Data were collected for wind speeds in the range about 7, 10 and 13 m/s. A data matrix was filled for clean, medium and heavy surface roughness. Baseline power curves, parametric pitch variation runs to establish testing pitch settings, high speed data collection runs with and without applied surface roughness were completed and analyzed. Data were compared using simple arithmetic mean, Fast Fourier Transform (FFT) analysis, rainflow counting algorithms and wavelet analysis. The NREL airfoils showed much less sensitivity to surface roughness. There were minimal root bending load differences. Annual energy production during long term operation is being determined. 9 refs., 7 figs.

  19. Cleaning supplies and equipment

    Science.gov (United States)

    ... gov/ency/patientinstructions/000443.htm Cleaning supplies and equipment To use the sharing features on this page, ... to clean supplies and equipment. Disinfecting Supplies and Equipment Start by wearing the right personal protective equipment ( ...

  20. Used equipment-standard contract elements

    Institute of Scientific and Technical Information of China (English)

    Gary F. Alexander

    2004-01-01

    @@ One thing that both the purchase of new and used equipment has in common is the need for a comprehensive purchase agreement. The big difference is that while repetitive purchases of new equipment often only require the modification of one or more sections of a contract, every used equipment transaction and contract is normally different.

  1. 7 CFR 58.626 - Packaging equipment.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Packaging equipment. 58.626 Section 58.626 Agriculture....626 Packaging equipment. Packaging equipment designed to mechanically fill and close single service... accessible for cleaning. The design and operation of the machine shall in no way contaminate the container...

  2. 14 CFR 121.605 - Airplane equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplane equipment. 121.605 Section 121.605..., FLAG, AND SUPPLEMENTAL OPERATIONS Dispatching and Flight Release Rules § 121.605 Airplane equipment. No person may dispatch or release an airplane unless it is airworthy and is equipped as prescribed in §...

  3. 30 CFR 56.4600 - Extinguishing equipment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Extinguishing equipment. 56.4600 Section 56... Control Welding/cutting/compressed Gases § 56.4600 Extinguishing equipment. (a) When welding, cutting... equivalent fire extinguishing equipment for the class of fire hazard present shall be at the worksite....

  4. 38 CFR 49.34 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Equipment. 49.34 Section... NON-PROFIT ORGANIZATIONS Post-Award Requirements Property Standards § 49.34 Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions...

  5. 30 CFR 77.1914 - Electrical equipment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electrical equipment. 77.1914 Section 77.1914 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH... Shaft Sinking § 77.1914 Electrical equipment. (a) Electric equipment employed below the collar of...

  6. 21 CFR 1271.200 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Equipment. 1271.200 Section 1271.200 Food and... CELLULAR AND TISSUE-BASED PRODUCTS Current Good Tissue Practice § 1271.200 Equipment. (a) General. To prevent the introduction, transmission, or spread of communicable diseases, equipment used in...

  7. 41 CFR 105-71.132 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Equipment. 105-71.132...-Award Requirements/Changes, Property, and Subawards § 105-71.132 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to equipment acquired under a grant or...

  8. 2 CFR 215.34 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 2 Grants and Agreements 1 2010-01-01 2010-01-01 false Equipment. 215.34 Section 215.34 Grants and... ORGANIZATIONS (OMB CIRCULAR A-110) Post Award Requirements Property Standards § 215.34 Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions...

  9. 14 CFR 1260.134 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Equipment. 1260.134 Section 1260.134..., Hospitals, and Other Non-Profit Organizations Property Standards § 1260.134 Equipment. (a) For grants and... research to not vest title in the recipient as exempt, equipment shall vest in the recipient subject...

  10. 7 CFR 51.58 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Equipment. 51.58 Section 51.58 Agriculture Regulations... Requirements for Plants Operating Under Continuous Inspection on A Contract Basis § 51.58 Equipment. All equipment used for receiving, washing, grading, packaging or storing shall be of such design, material...

  11. 50 CFR 260.102 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... with Good Manufacturing Practice Regulations, 21 CFR part 128. ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Equipment. 260.102 Section 260.102... Basis 1 § 260.102 Equipment. All equipment used for receiving, washing, segregating, picking,...

  12. 36 CFR 1210.34 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Equipment. 1210.34 Section..., HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Property Standards § 1210.34 Equipment. (a) Title to equipment acquired by a recipient with NHPRC funds shall vest in the recipient,...

  13. 24 CFR 84.34 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 24 Housing and Urban Development 1 2010-04-01 2010-04-01 false Equipment. 84.34 Section 84.34... NON-PROFIT ORGANIZATIONS Post-Award Requirements Property Standards § 84.34 Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions...

  14. 17 CFR 256.307 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Equipment. 256.307 Section 256... COMPANY ACT OF 1935 Service Company Property Accounts § 256.307 Equipment. This account shall include the cost of equipment owned by the service company and used in rendering services such as...

  15. 22 CFR 145.34 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Equipment. 145.34 Section 145.34 Foreign..., HOSPITALS, AND OTHER NON-PROFIT ORGANIZATIONS Post-Award Requirements Property Standards § 145.34 Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the...

  16. 30 CFR 57.4600 - Extinguishing equipment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Extinguishing equipment. 57.4600 Section 57... and Control Welding/cutting/compressed Gases § 57.4600 Extinguishing equipment. (a) When welding... equivalent fire extinguishing equipment for the class of fire hazard present shall be at the worksite....

  17. 22 CFR 226.34 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Equipment. 226.34 Section 226.34 Foreign... ORGANIZATIONS Post-award Requirements Property Standards § 226.34 Equipment. (a) Unless the agreement provides otherwise, title to equipment acquired by a recipient with Federal funds shall vest in the...

  18. 40 CFR 30.34 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Equipment. 30.34 Section 30.34... NON-PROFIT ORGANIZATIONS Post-Award Requirements Property Standards § 30.34 Equipment. (a) Title to equipment acquired by a recipient with Federal funds shall vest in the recipient, subject to conditions...

  19. 46 CFR 28.405 - Hydraulic equipment.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Hydraulic equipment. 28.405 Section 28.405 Shipping... Operate With More Than 16 Individuals on Board § 28.405 Hydraulic equipment. (a) Each hydraulic system... than four times the system maximum operating pressure. (c) Each hydraulic system must be equipped...

  20. 46 CFR 28.880 - Hydraulic equipment.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Hydraulic equipment. 28.880 Section 28.880 Shipping... INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.880 Hydraulic equipment. (a) Each hydraulic system must be... times the system's maximum operating pressure. (c) Each hydraulic system must be equipped with at...

  1. 46 CFR 184.220 - Cooking equipment.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Cooking equipment. 184.220 Section 184.220 Shipping...) VESSEL CONTROL AND MISCELLANEOUS SYSTEMS AND EQUIPMENT Cooking and Heating § 184.220 Cooking equipment. (a) Doors on a cooking appliance must be provided with hinges and locking devices to...

  2. 46 CFR 121.220 - Cooking equipment.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Cooking equipment. 121.220 Section 121.220 Shipping... SYSTEMS AND EQUIPMENT Cooking and Heating § 121.220 Cooking equipment. (a) Doors on a cooking appliance... cooking appliance must be installed to prevent movement in heavy seas. (c) For a grill or similar type...

  3. Advancements in adaptive aerodynamic technologies for airfoils and wings

    Science.gov (United States)

    Jepson, Jeffrey Keith

    Although aircraft operate over a wide range of flight conditions, current fixed-geometry aircraft are optimized for only a few of these conditions. By altering the shape of the aircraft, adaptive aerodynamics can be used to increase the safety and performance of an aircraft by tailoring the aircraft for multiple flight conditions. Of the various shape adaptation concepts currently being studied, the use of multiple trailing-edge flaps along the span of a wing offers a relatively high possibility of being incorporated on aircraft in the near future. Multiple trailing-edge flaps allow for effective spanwise camber adaptation with resulting drag benefits over a large speed range and load alleviation at high-g conditions. The research presented in this dissertation focuses on the development of this concept of using trailing-edge flaps to tailor an aircraft for multiple flight conditions. One of the major tasks involved in implementing trailing-edge flaps is in designing the airfoil to incorporate the flap. The first part of this dissertation presents a design formulation that incorporates aircraft performance considerations in the inverse design of low-speed laminar-flow adaptive airfoils with trailing-edge cruise flaps. The benefit of using adaptive airfoils is that the size of the low-drag region of the drag polar can be effectively increased without increasing the maximum thickness of the airfoil. Two aircraft performance parameters are considered: level-flight maximum speed and maximum range. It is shown that the lift coefficients for the lower and upper corners of the airfoil low-drag range can be appropriately adjusted to tailor the airfoil for these two aircraft performance parameters. The design problem is posed as a part of a multidimensional Newton iteration in an existing conformal-mapping based inverse design code, PROFOIL. This formulation automatically adjusts the lift coefficients for the corners of the low-drag range for a given flap deflection as

  4. Mechanisms of sound amplification and sound reduction in the flapping flight of side-by-side airfoils

    Science.gov (United States)

    Manela, A.; Halachmi, M.

    2015-06-01

    The acoustic signature of side-by-side airfoils, subject to small-amplitude harmonic pitching and incoming flow unsteadiness, is investigated. The two-dimensional near-field problem is formulated using thin-airfoil theory, where flow unsteadiness is modeled as a passing line vortex, and wake evolution is calculated via the Brown and Michael formula. Assuming that the setup is acoustically compact, acoustic radiation is obtained by means of the Powell-Howe acoustic analogy. The associated compact Green's function is calculated numerically using potential-flow analysis of the fluid-structure flow domain. Results, comparing the acoustic radiation of the double-airfoil system to a reference case of a single airfoil, point to several mechanisms of sound attenuation and sound amplification, caused by airfoil-airfoil and airfoils-wake interactions. It is found that counter-phase pitching of the airfoils results in effective cloaking of the system, which otherwise becomes significantly noisy (as a 5/2-power of the pitching frequency) at large frequencies. In addition, depending on the distance between airfoils, in-phase pitching may result in an acoustic signature equivalent to a single airfoil (when the airfoils are adjacent) or to two separate airfoils (when the airfoils are far apart). In general, flow unsteadiness produces more sound when interacting with a double (compared with a single) airfoil setup. However, airfoils' nonlinear wake-wake interactions give rise to a sound reduction mechanism, which becomes most efficient at times when incoming vorticity passes above airfoils' leading and trailing edges. The present scheme can be readily extended to consider the acoustic properties of various double-airfoil configurations, as well as multiple (> 2) airfoil setups.

  5. 42 CFR 414.226 - Oxygen and oxygen equipment.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Oxygen and oxygen equipment. 414.226 Section 414... Equipment and Prosthetic and Orthotic Devices § 414.226 Oxygen and oxygen equipment. (a) Payment rules—(1) Oxygen equipment. Payment for rental of oxygen equipment is made based on a monthly fee schedule...

  6. 7 CFR 58.229 - Filler and packaging equipment.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Filler and packaging equipment. 58.229 Section 58.229....229 Filler and packaging equipment. All filling and packaging equipment shall be of sanitary... equipment should comply with the 3-A Sanitary Standards for equipment for Packaging Dry Milk and Dry...

  7. Experimental verification of the new RISOe-A1 airfoil family for wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Dahl, K.S.; Fuglsang, P.; Antoniou, I. [Risoe National Lab., Roskilde (Denmark)

    1999-03-01

    This paper concerns the experimental verification of a new airfoil family for wind turbines. The family consist of airfoils in the relative thickness range from 15% to 30%. Three airfoils, Risoe-A1-18, Risoe-A1-21, and Risoe-A1-24 were tested in a wind tunnel. The verification consisted of both static and dynamic measurements. Here, the static results are presented for a Reynolds number of 1.6x10{sup 6} for the following airfoil configurations: smooth surface (all three airfoils) and Risoe-A1-24 mounted with leading edge roughness, vortex generators, and Gurney-flaps, respectively. All three airfoils have constant lift curve slope and almost constant drag coefficient until the maximum lift coefficient of about 1.4 is reached. The experimental results are compared with corresponding computational from the general purpose flow solver, EllipSys2D, showing good agreement. (au)

  8. Modeling Creep-Induced Stress Relaxation at the Leading Edge of SiC/SiC Airfoils

    Science.gov (United States)

    Lang, Jerry; DiCarlo, James A.

    2007-01-01

    Anticipating the implementation of advanced SiC/SiC composites into internally cooled airfoil components within the turbine section of future aero-propulsion engines, the primary objective of this study was to develop physics-based analytical and finite-element modeling tools to predict the effects of composite creep and stress relaxation at the airfoil leading edges, which will generally experience large thermal gradients at high temperatures. A second objective was to examine how some advanced NASA-developed SiC/SiC systems coated with typical EBC materials would behave as leading edge materials in terms of long-term steady-state operating temperatures. Because of the complexities introduced by mechanical stresses inherent in internally cooled airfoils, a simple cylindrical thin-walled tube model subjected to thermal stresses only is employed for the leading edge, thereby obtaining a best-case scenario for the material behavior. In addition, the SiC/SiC composite materials are assumed to behave as isotropic materials with temperature-dependent viscoelastic creep behavior as measured in-plane on thin-walled panels. Key findings include: (1) without mechanical stresses and for typical airfoil geometries, as heat flux is increased through the leading edge, life-limiting tensile crack formation will occur first in the hoop direction on the inside wall of the leading edge; (2) thermal gradients through all current SiC/SiC systems should be kept below approx.300 F at high temperatures to avoid this cracking; (3) at temperatures near the maximum operating temperatures of advanced SiC/SiC systems, thermal stresses induced by the thermal gradients will beneficially relax with time due to creep; (4) although stress relaxation occurs, the maximum gradient should still not exceed 300oF because of residual tensile stress buildup on the airfoil outer wall during cool-down; and (5) without film cooling and mechanical stresses, the NASA-developed N26 SiC/SiC system with thru

  9. Containment and Surveillance Equipment Compendium

    International Nuclear Information System (INIS)

    The Containment and Surveillance Equipment Compendium contains information sections describing the application and status of seals, optical surveillance systems, and monitors for international safeguards systems. The Compendium is a collection of information on equipment in use (generally by the IAEA) or under development in the US in diverse programs being conducted at numerous facilities under different sponsors. The Compendium establishes a baseline for the status and applications of C/S equipment and is a tool to assist in the planning of future C/S hardware development activities. The Appendix contains design concepts which can be developed to meet future goals

  10. A critical evaluation of the predictions of the NASA-Lockheed multielement airfoil computer program

    Science.gov (United States)

    Brune, G. W.; Manke, J. W.

    1978-01-01

    Theoretical predictions of several versions of the multielement airfoil computer program are evaluated. The computed results are compared with experimental high lift data of general aviation airfoils with a single trailing edge flap, and of airfoils with a leading edge flap and double slotted trailing edge flaps. Theoretical and experimental data include lift, pitching moment, profile drag and surface pressure distributions, boundary layer integral parameters, skin friction coefficients, and velocity profiles.

  11. S833, S834, and S835 Airfoils: November 2001--November 2002

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D. M.

    2005-08-01

    A family of quiet, thick, natural-laminar-flow airfoils, the S833, S834, and S835, for 1 - 3-meter-diameter, variable-speed/variable-pitch, horizontal-axis wind turbines has been designed and analyzed theoretically. The two primary objectives of high maximum lift, relatively insensitive to roughness, and low profile drag have been achieved. The airfoils should exhibit docile stalls, which meet the design goal. The constraints on the pitching moment and the airfoils thicknesses have been satisfied.

  12. S830, S831, and S832 Airfoils: November 2001-November 2002

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D. M.

    2005-08-01

    A family of quiet, thick, natural-laminar-flow airfoils, the S830, S831, and S832, for 40 - 50-meter-diameter, variable-speed/variable-pitch, horizontal-axis wind turbines has been designed and analyzed theoretically. The two primary objectives of high maximum lift, relatively insensitive to roughness, and low profile drag have been achieved. The airfoils should exhibit docile stalls, which meet the design goal. The constraints on the pitching moment and the airfoils thicknesses have been satisfied.

  13. Investigation on Improved Correlation of CFD and EFD for Supercritical Airfoil

    OpenAIRE

    Xin Xu; Da-wei Liu; De-hua Chen; Zhi Wei; Yuan-jing Wang

    2014-01-01

    It is necessary to improve the correlation between CFD and EFD through the correction of EFD results and validation of CFD method, thus investigating the aerodynamic characteristics of supercritical airfoil perfectly. In this study, NASA SC (2) -0714 airfoil is numerically simulated and compared with NASA corrected experimental results to validate the CFD method. The Barnwell-Sewell method is applied to correct sidewall effects for experimental results of typical supercritical airfoil CH obta...

  14. Effects of real airfoil geometry on leading edge gust interaction noise

    OpenAIRE

    Gill, James; Zhang, Xin; Joseph, Phillip; Node-Langlois, Thomas

    2013-01-01

    High-order computational aeroacoustic methods are applied to the modeling of noise due to interactions between gusts and the leading edge of real symmetric airfoils. The effects of airfoil thickness and leading edge radius on noise are investigated systematically and in-dependently for the first time, at higher frequencies than previously used in computational methods. Single frequency harmonic gusts are interacted with airfoils of varying geometry at zero angle of attack. Increases in both l...

  15. The Development of Erosion and Impact Resistant Turbine Airfoil Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2007-01-01

    Thermal barrier coatings are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments and extend component lifetimes. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Advanced erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the doped thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion and impact damage mechanisms of the thermal barrier coatings will also be discussed.

  16. Characterization of the Flow Separation of a Variable Camber Airfoil

    International Nuclear Information System (INIS)

    An experimental investigation is carried out to study the flow separation behaviors of a variable camber airfoil. The aerodynamic load measurements and related flow visualization show that there are two types of stalls caused by the deformation on the camber: the leading-edge stall and the trailing-edge stall. Static measurements of aerodynamic force show a drastic leading-edge stall, while the serial measurements on an airfoil with camber deformation illustrate a trailing-edge stall and gradual bending-over on the aerodynamic coefficient curve. Under flow separation circumstances, the flow structure is related not only to current boundary conditions, but also the previous flow characteristics, so the quasi-steady aerodynamic characteristics are significantly distinct from those of the static measurements. (fundamental areas of phenomenology(including applications))

  17. Effect of oscillation frequency on wind turbine airfoil dynamic stall

    International Nuclear Information System (INIS)

    At the same oscillation amplitude, Reynolds Number, mean angle of attack, the dynamic stall characteristics of the NREL S809 airfoil undergoing sinusoidal pitch oscillations of different oscillation frequencies were investigated with modified k-ω SST turbulence model of CFD solution for two-dimensional numerical simulation. The predicted lift, drag coefficients and moment coefficients were compared with the Ohio State University wind tunnel test results, which showed a good agreement. The birth, development and breaking off of eddies were analyzed through streamline distribution around airfoil and the influence of oscillation frequencies on dynamic stall characteristics was also described and analyzed in detail, which enrich the database of dynamic stall characteristics needed by the quantization of oscillation frequencies on dynamic characteristics and prove that sliding mesh method is reliable when dealing with dynamic stall problems

  18. Turbulent flow simulation of the NREL S809 airfoil

    Energy Technology Data Exchange (ETDEWEB)

    Guerri, Ouahiba; Bouhadef, Khadidja; Harhad, Ameziane

    2006-05-15

    Numerical computations are carried out for the NREL S809 airfoil. The flow is modelled using an unsteady incompressible Reynolds Averaged Navier-Stokes solver. Two turbulence models (SST {kappa}/{omega}of Menter and RNG {kappa}/{epsilon}) are applied to close the RANS equations. All computations are performed assuming fully turbulent flow. The flow field is analyzed at various angles of attack from 0 to 20 degrees. Lift and drag forces are obtained from the computations by integrating the pressure and shear stress over the blade surface. The performance of the two turbulence models is compared and the influence of the free stream turbulence intensity is checked. The results confirm the satisfactory performance of the SST {kappa}/{omega} model of Menter for modelling turbulent flow around airfoils. (author)

  19. Airfoil for a turbine of a gas turbine engine

    Science.gov (United States)

    Liang, George

    2010-12-21

    An airfoil for a turbine of a gas turbine engine is provided. The airfoil comprises a main body comprising a wall structure defining an inner cavity adapted to receive a cooling air. The wall structure includes a first diffusion region and at least one first metering opening extending from the inner cavity to the first diffusion region. The wall structure further comprises at least one cooling circuit comprising a second diffusion region and at least one second metering opening extending from the first diffusion region to the second diffusion region. The at least one cooling circuit may further comprise at least one third metering opening, at least one third diffusion region and a fourth diffusion region.

  20. Control theory based airfoil design using the Euler equations

    Science.gov (United States)

    Jameson, Antony; Reuther, James

    1994-01-01

    This paper describes the implementation of optimization techniques based on control theory for airfoil design. In our previous work it was shown that control theory could be employed to devise effective optimization procedures for two-dimensional profiles by using the potential flow equation with either a conformal mapping or a general coordinate system. The goal of our present work is to extend the development to treat the Euler equations in two-dimensions by procedures that can readily be generalized to treat complex shapes in three-dimensions. Therefore, we have developed methods which can address airfoil design through either an analytic mapping or an arbitrary grid perturbation method applied to a finite volume discretization of the Euler equations. Here the control law serves to provide computationally inexpensive gradient information to a standard numerical optimization method. Results are presented for both the inverse problem and drag minimization problem.

  1. Numerical Investigation of Flow Control by Suction and Injection on a Subsonic Airfoil

    OpenAIRE

    M. H. Shojaefard; A. R. Noorpoor; A. Avanesians; M. Ghaffarpour

    2005-01-01

    This study presents a numerical study concerning flow control by suction and injection. The case studied is the flow field over a subsonic airfoil with four suction and injection slots on the suction side of the airfoil. Five different angles of attack, 0, 5, 10, 13.3 and 20 with the Mach number of 0.15 are studied. Three cases are studied in each angle of attack. The three cases are airfoil with surface suction, surface injection and the base airfoil. A commercial CFD code, the FLUENT, is us...

  2. Flow Control on Low-Pressure Turbine Airfoils Using Vortex Generator Jets

    Science.gov (United States)

    Volino, Ralph J.; Ibrahim, Mounir B.; Kartuzova, Olga

    2010-01-01

    Motivation - Higher loading on Low-Pressure Turbine (LPT) airfoils: Reduce airfoil count, weight, cost. Increase efficiency, and Limited by suction side separation. Growing understanding of transition, separation, wake effects: Improved models. Take advantage of wakes. Higher lift airfoils in use. Further loading increases may require flow control: Passive: trips, dimples, etc. Active: plasma actuators, vortex generator jets (VGJs). Can increased loading offset higher losses on high lift airfoils. Objectives: Advance knowledge of boundary layer separation and transition under LPT conditions. Demonstrate, improve understanding of separation control with pulsed VGJs. Produce detailed experimental data base. Test and develop computational models.

  3. Airfoil lance apparatus for homogeneous humidification and sorbent dispersion in a gas stream

    Science.gov (United States)

    Myers, Robert B.; Yagiela, Anthony S.

    1990-12-25

    An apparatus for spraying an atomized mixture into a gas stream comprises a stream line airfoil member having a large radius leading edge and a small radius trailing edge. A nozzle assembly pierces the trailing edge of the airfoil member and is concentrically surrounded by a nacelle which directs shielding gas from the interior of the airfoil member around the nozzle assembly. Flowable medium to be atomized and atomizing gas for atomizing the medium are supplied in concentric conduits to the nozzle. A plurality of nozzles each surrounded by a nacelle are spaced along the trailing edge of the airfoil member.

  4. An Exploratory Investigation of a Slotted, Natural-Laminar-Flow Airfoil

    Science.gov (United States)

    Somers, Dan M.

    2012-01-01

    A 15-percent-thick, slotted, natural-laminar-flow (SNLF) airfoil, the S103, for general aviation applications has been designed and analyzed theoretically and verified experimentally in the Langley Low-Turbulence Pressure Tunnel. The two primary objectives of high maximum lift and low profile drag have been achieved. The constraints on the pitching moment and the airfoil thickness have been satisfied. The airfoil exhibits a rapid stall, which does not meet the design goal. Comparisons of the theoretical and experimental results show good agreement. Comparison with the baseline, NASA NLF(1)-0215F airfoil confirms the achievement of the objectives.

  5. 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. .

  6. Validation of the CQU-DTU-LN1 series of airfoils

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Zhu, Wei Jun; Fischer, Andreas;

    2014-01-01

    The CQU-DTU-LN1 series of airfoils were designed with an objective of high lift and low noise emission. In the design process, the aerodynamic performance is obtained using XFOIL while noise emission is obtained with the BPM model. In this paper we present some validations of the designed CQU......, the designed Cl and Cl/Cd agrees well with the experiment and are in general higher than those of the NACA airfoil. For the acoustic features, the noise emission of the LN118 airfoil is compared with the acoustic measurements and that of the NACA airfoil. Comparisons show that the BPM model can predict...

  7. Design and Wind Tunnel Testing of a Thick, Multi-Element High-Lift Airfoil

    DEFF Research Database (Denmark)

    Zahle, Frederik; Gaunaa, Mac; Sørensen, Niels N.;

    2012-01-01

    In this work a 2D CFD solver has been used to optimize the shape of a leading edge slat with a chord length of 30% of the main airfoil which was 40% thick. The airfoil configuration was subsequently tested in a wind tunnel and compared to numerical predictions. The multi-element airfoil was...... predicted to achieve a Cl−max of 3.1 based on the main airfoil chord length, which was confirmed in the wind tunnel campaign. Using wake rake traversal and wool tuft flow visualization wall interference effects were investigated, which were found to be a source of considerable uncertainty when measuring on...

  8. Design of the wind turbine airfoil family RISOe-A-XX

    Energy Technology Data Exchange (ETDEWEB)

    Dahl, K.S.; Fuglsang, P.

    1998-12-01

    A method for design of wind turbine airfoils is presented. The design method is based on direct numerical optimization of a B-spline representation of the airfoil shape. For flexibility, the optimization algorithm relies on separate, stand alone tools for the analysis of aerodynamic and structural properties. The panel method based XFOIL is used during the optimization whereas the Navier-Stokes solver EllipSys2D is used in the evaluation of the results. The method is demonstrated by the design of an airfoil family composed of 7 airfoils ranging in thickness from 12% to 30%. The design is based on Reynolds and Mach numbers representative of a 600 kW wind turbine. The airfoils are designed to have maximum lift-drag ratio until just below stall, a design lift coefficient of about 1.55 at an angle of attack of 10 deg. and a maximum lift coefficient of 1.65. The airfoils are made insensitive to leading edge roughness by securing that transition from laminar to turbulent flow on the suction side occurs close to the leading edge for post stall angles of attack. The design method and the airfoil family provides a sound basis for further enhancing the characteristics of airfoils for wind turbines and to tailor airfoils for specific rotor sizes and power regulation principles. (au) EFP-95. 3 tabs., 24 ills., 31 refs.

  9. 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...

  10. Turbine blade having a constant thickness airfoil skin

    Science.gov (United States)

    Marra, John J

    2012-10-23

    A turbine blade is provided for a gas turbine comprising: a support structure comprising a base defining a root of the blade and a framework extending radially outwardly from the base, and an outer skin coupled to the support structure framework. The skin has a generally constant thickness along substantially the entire radial extent thereof. The framework and the skin define an airfoil of the blade.

  11. Design, Simulation, and Wind Tunnel Verication of a Morphing Airfoil

    OpenAIRE

    Gustafson, Eric Andrew

    2011-01-01

    The application of smart materials to control the flight dynamics of a Micro Air Vehicle (MAV) has numerous benefits over traditional servomechanisms. Under study is wing morphing achieved through the use of piezoelectric Macro Fiber Composites (MFCs). These devices exhibit low power draw but excellent bandwidth characteristics. This thesis provides a background in the 2D analytical and computer modeling tools and methods needed to design and characterize an MFC-actuated airfoil. A com...

  12. CFD and experimental study of aerodynamic degradation of iced airfoils

    Czech Academy of Sciences Publication Activity Database

    Horák, V.; Rozehnal, D.; Chára, Zdeněk; Hyll, A.

    Praha: Ústav termomechaniky AV ČR v. v. i, 2008 - (Jonáš, P.; Uruba, V.), č. 007 ISBN 978-80-87012-14-7. [Colloquium FLUID DYNAMICS 2008. Praha (CZ), 22.10.2008-24.10.2008] R&D Projects: GA ČR GA103/07/0136; GA MPO FT-TA4/044 Institutional research plan: CEZ:AV0Z20600510 Keywords : CFD * lift coefficient * iced airfoil Subject RIV: BK - Fluid Dynamics

  13. 45 CFR 1174.32 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Equipment. 1174.32 Section 1174.32 Public Welfare... STATE AND LOCAL GOVERNMENTS Post-Award Requirements Changes, Property, and Subawards § 1174.32 Equipment. (a) Title. Subject to the obligations and conditions set forth in this section, title to...

  14. Simulasi Numerik Dynamic Stall Pada Airfoil Yang Berosilasi

    Directory of Open Access Journals (Sweden)

    Galih S.T.A. Bangga

    2012-09-01

    Full Text Available Kebutuhan analisa pada sudu helikopter, kompresor, kincir angin dan struktur streamline lainya yang beroperasi pada angle of attack yang tinggi dan melibatkan instationary effects yang disebut dynamic stall menjadi semakin penting. Fenomena ini ditandai dengan naiknya dynamic lift melewati static lift maksimum pada critical static stall angle, vortex yang terbentuk pada leading edge mengakibatkan naiknya suction contribution yang kemudian terkonveksi sepanjang permukaan hingga mencapai trailling edge diikuti terbentuknya trailling edge vortex yang menunjukkan terjadinya lift stall. Fenomena ini sangat berbahaya terhadap struktur airfoil itu sendiri. Secara umum, beban fatique yang ditimbulkan oleh adanya efek histerisis karena fluktuasi gaya lift akibat induksi vibrasi lebih besar dibandingkan kondisi statis. Simulasi numerik dilakukan secara 2D dengan menggunakan profil Boeing-Vertol V23010-1.58 pada α0 = 14.92°. Standard-kω dan SST-kω digunakan sebagai URANS turbulence modelling. Model osilasi dari airfoil disusun dalam suatu user defined function (UDF. Gerakan meshing beserta airfoil diakomodasi dengan menggunakan dynamic mesh approach. Simulasi numerik menunjukkan bahwa, model SST-kω menunjukkan performa yang lebih baik dibandingkan dengan Standard-kω. Fenomena travelling vortex yang terjadi mampu ditangkap dengan baik, meski pada angle of attack yang tinggi URANS turbulence model gagal memprediksikan fenomena yang terjadi karena dominasi efek 3D.

  15. Light Imaging Section

    Data.gov (United States)

    Federal Laboratory Consortium — The mission of the Light Imaging Section is to give NIAMS scientists access to state-of-the-art light imaging equipment and to offer training and assistance at all...

  16. Simulation of flow over double-element airfoil and wind tunnel test for use in vertical axis wind turbine

    International Nuclear Information System (INIS)

    Nowadays, small vertical axis wind turbines are receiving more attention due to their suitability in micro-electricity generation. There are few vertical axis wind turbine designs with good power curve. However, the efficiency of power extraction has not been improved. Therefore, an attempt has been made to utilize high lift technology for vertical axis wind turbines in order to improve power efficiency. High lift is obtained by double-element airfoil mainly used in aeroplane wing design. In this current work a low Reynolds number airfoil is selected to design a double-element airfoil blade for use in vertical axis wind turbine to improve the power efficiency. Double-element airfoil blade design consists of a main airfoil and a slat airfoil. Orientation of slat airfoil is a parameter of investigation in this paper and air flow simulation over double-element airfoil. With primary wind tunnel test an orientation parameter for the slat airfoil is initially obtained. Further a computational fluid dynamics (CFD) has been used to obtain the aerodynamic characteristics of double-element airfoil. The CFD simulations were carried out using ANSYS CFX software. It is observed that there is an increase in the lift coefficient by 26% for single-element airfoil at analysed conditions. The CFD simulation results were validated with wind tunnel tests. It is also observe that by selecting proper airfoil configuration and blade sizes an increase in lift coefficient can further be achieved

  17. Simulation of flow over double-element airfoil and wind tunnel test for use in vertical axis wind turbine

    Science.gov (United States)

    Chougule, Prasad; Nielsen, Søren R. K.

    2014-06-01

    Nowadays, small vertical axis wind turbines are receiving more attention due to their suitability in micro-electricity generation. There are few vertical axis wind turbine designs with good power curve. However, the efficiency of power extraction has not been improved. Therefore, an attempt has been made to utilize high lift technology for vertical axis wind turbines in order to improve power efficiency. High lift is obtained by double-element airfoil mainly used in aeroplane wing design. In this current work a low Reynolds number airfoil is selected to design a double-element airfoil blade for use in vertical axis wind turbine to improve the power efficiency. Double-element airfoil blade design consists of a main airfoil and a slat airfoil. Orientation of slat airfoil is a parameter of investigation in this paper and air flow simulation over double-element airfoil. With primary wind tunnel test an orientation parameter for the slat airfoil is initially obtained. Further a computational fluid dynamics (CFD) has been used to obtain the aerodynamic characteristics of double-element airfoil. The CFD simulations were carried out using ANSYS CFX software. It is observed that there is an increase in the lift coefficient by 26% for single-element airfoil at analysed conditions. The CFD simulation results were validated with wind tunnel tests. It is also observe that by selecting proper airfoil configuration and blade sizes an increase in lift coefficient can further be achieved.

  18. 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.

  19. Airfoil-shaped micro-mixers for reducing fouling on membrane surfaces

    Science.gov (United States)

    Ho, Clifford K; Altman, Susan J; Clem, Paul G; Hibbs, Michael; Cook, Adam W

    2012-10-23

    An array of airfoil-shaped micro-mixers that enhances fluid mixing within permeable membrane channels, such as used in reverse-osmosis filtration units, while minimizing additional pressure drop. The enhanced mixing reduces fouling of the membrane surfaces. The airfoil-shaped micro-mixer can also be coated with or comprised of biofouling-resistant (biocidal/germicidal) ingredients.

  20. S819, S820, and S821 Airfoils: October 1992--November 1993

    Energy Technology Data Exchange (ETDEWEB)

    Somers, D. M.

    2005-01-01

    A family of thick airfoils for 10- to 20-meter, stall regulated, horizontal-axis wind turbines, the S819, S820, and S821, has been designed and analyzed theoretically. The primary objectives of restrained maximum lift, insensitive to roughness, and low profile drag have been achieved. The constraints on the pitching moments and airfoil thicknesses have been satisfied.

  1. Numerical Solution of Compressible Steady Flows around the RAE 2822 Airfoil

    Science.gov (United States)

    Kryštůfek, P.; Kozel, K.

    2014-03-01

    The article presents results of a numerical solution of subsonic, transonic and supersonic flows described by the system of Navier-Stokes equations in 2D laminar compressible flows around the RAE 2822 airfoil. Authors used FVM multistage Runge-Kutta method to numerically solve the flows around the RAE 2822 airfoil.

  2. Numerical Solution of Compressible Steady Flows around the RAE 2822 Airfoil

    Directory of Open Access Journals (Sweden)

    Kryštůfek P.

    2014-03-01

    Full Text Available The article presents results of a numerical solution of subsonic, transonic and supersonic flows described by the system of Navier-Stokes equations in 2D laminar compressible flows around the RAE 2822 airfoil. Authors used FVM multistage Runge-Kutta method to numerically solve the flows around the RAE 2822 airfoil.

  3. Aerodynamic Force and Flow Structures of Two Airfoils in Flapping Motions

    CERN Document Server

    Lan, S L; Lan, Shi Long; Sun, Mao

    2001-01-01

    Aerodynamic force and flow structures of two airfoils in tandem configuration performing flapping motions are studied, using the method of solving the Navier-Stokes equations in moving overset grids. Three typical phase differences between the fore- and aft-airfoil flapping cycles are considered.

  4. Rime ice accretion and its effect on airfoil performance. Ph.D. Thesis. Final Report

    Science.gov (United States)

    Bragg, M. B.

    1982-01-01

    A methodology was developed to predict the growth of rime ice, and the resulting aerodynamic penalty on unprotected, subcritical, airfoil surfaces. The system of equations governing the trajectory of a water droplet in the airfoil flowfield is developed and a numerical solution is obtained to predict the mass flux of super cooled water droplets freezing on impact. A rime ice shape is predicted. The effect of time on the ice growth is modeled by a time-stepping procedure where the flowfield and droplet mass flux are updated periodically through the ice accretion process. Two similarity parameters, the trajectory similarity parameter and accumulation parameter, are found to govern the accretion of rime ice. In addition, an analytical solution is presented for Langmuir's classical modified inertia parameter. The aerodynamic evaluation of the effect of the ice accretion on airfoil performance is determined using an existing airfoil analysis code with empirical corrections. The change in maximum lift coefficient is found from an analysis of the new iced airfoil shape. The drag correction needed due to the severe surface roughness is formulated from existing iced airfoil and rough airfoil data. A small scale wind tunnel test was conducted to determine the change in airfoil performance due to a simulated rime ice shape.

  5. Surface pressure and aerodynamic loads determination of a transonic airfoil based on particle image velocimetry

    NARCIS (Netherlands)

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

    2009-01-01

    The present investigation assesses a procedure to extract the aerodynamic loads and pressure distribution on an airfoil in the transonic flow regime from particle image velocimetry (PIV) measurements. The wind tunnel model is a two-dimensional NACA-0012 airfoil, and the PIV velocity data are used to

  6. Experimental studies of flow separation and stalling on two-dimensional airfoils at low speeds. Phase 2: Studies with Fowler flap extended

    Science.gov (United States)

    Seetharam, H. C.; Wentz, W. H., Jr.

    1975-01-01

    Results were given on experimental studies of flow separation and stalling on a two-dimensional GA(W)-1 17 percent thick airfoil with an extended Fowler flap. Experimental velocity profiles obtained from a five tube probe survey with optimum flap gap and overlap setting (flap at 40 deg) are shown at various stations above, below, and behind the airfoil/flap combination for various angles of attack. The typical zones of steady flow, intermittent turbulence, and large scale turbulence were obtained from a hot wire anemometer survey and are depicted graphically for an angle of attack of 12.5 deg. Local skin friction distributions were obtained and are given for various angles of attack. Computer plots of the boundary layer profiles are shown for the case of the flap at 40 deg. Static pressure contours are also given. A GA(W)-2 section model was fabricated with 30 percent Fowler flaps and with pressure tabs.

  7. Influences of surface temperature on a low camber airfoil aerodynamic performances

    Directory of Open Access Journals (Sweden)

    Valeriu DRAGAN

    2016-03-01

    Full Text Available The current note refers to the comparison between a NACA 2510 airfoil with adiabatic walls and the same airfoil with heated patches. Both suction and pressure sides were divided into two regions covering the leading edge (L.E. and trailing edge (T.E.. A RANS method sensitivity test has been performed in the preliminary stage while for the extended 3D cases a DES-SST approach was used. Results indicate that surface temperature distribution influences the aerodynamics of the airfoil, in particular the viscous drag component but also the lift of the airfoil. Moreover, the influence depends not only on the surface temperature but also on the positioning of the heated surfaces, particularly in the case of pressure lift and drag. Further work will be needed to optimize the temperature distribution for airfoil with higher camber.

  8. Experimental Investigation on the Aerodynamic Performance of NLF-0414 Iced-Airfoil

    Directory of Open Access Journals (Sweden)

    abbas ebrahimi

    2016-01-01

    Full Text Available Icing phenomenon on a natural laminar flow airfoil (NLF-0414 has been experimentally investigated. Double horn glaze ice geometry which was acquired during a 15 minutes spray time at-2.23℃ with liquid water content and a median volumetric diameter of 1.0 g/m3 and 20 μm, has been extracted from database of NASA Lewis Research Center. Pressure distribution over airfoil surfacewas evaluated at angles of attack between -2 to 6 degrees for both iced and clean airfoils. Aerodynamics performance degradation of the iced airfoil has been studied and it is shown that double horn ice accretion, due to its unique geometry, severely affects aerodynamic characteristics of natural laminar flow airfoils. Reattachment locations have been evaluated for upper and lower separation bubbles. The upper surface separation bubble was seen to increase in size in contrary to the lower surface separation bubble.

  9. Materials for Advanced Turbine Engines (MATE). Project 4: Erosion resistant compressor airfoil coating

    Science.gov (United States)

    Rashid, J. M.; Freling, M.; Friedrich, L. A.

    1987-01-01

    The ability of coatings to provide at least a 2X improvement in particulate erosion resistance for steel, nickel and titanium compressor airfoils was identified and demonstrated. Coating materials evaluated included plasma sprayed cobalt tungsten carbide, nickel carbide and diffusion applied chromium plus boron. Several processing parameters for plasma spray processing and diffusion coating were evaluated to identify coating systems having the most potential for providing airfoil erosion resistance. Based on laboratory results and analytical evaluations, selected coating systems were applied to gas turbine blades and evaluated for surface finish, burner rig erosion resistance and effect on high cycle fatigue strength. Based on these tests, the following coatings were recommended for engine testing: Gator-Gard plasma spray 88WC-12Co on titanium alloy airfoils, plasma spray 83WC-17Co on steel and nickel alloy airfoils, and Cr+B on nickel alloy airfoils.

  10. On the attenuating effect of permeability on the low frequency sound of an airfoil

    Science.gov (United States)

    Weidenfeld, M.; Manela, A.

    2016-08-01

    The effect of structure permeability on the far-field radiation of a thin airfoil is studied. Assuming low-Mach and high-Reynolds number flow, the near- and far-field descriptions are investigated at flapping-flight and unsteady flow conditions. Analysis is carried out using thin-airfoil theory and compact-body-based calculations for the hydrodynamic and acoustic fields, respectively. Airfoil porosity is modeled via Darcy's law, governed by prescribed distribution of surface intrinsic permeability. Discrete vortex model is applied to describe airfoil wake evolution. To assess the impact of penetrability, results are compared to counterpart predictions for the sound of an impermeable airfoil. Considering the finite-chord airfoil as "acoustically transparent", the leading-order contribution of surface porosity is obtained in terms of an acoustic dipole. It is shown that, at all flow conditions considered, porosity causes attenuation in outcome sound level. This is accompanied by a time-delay in the pressure signal, reflecting the mediating effect of permeability on the interaction of fluid flow with airfoil edge points. To the extent that thin-airfoil theory holds (requiring small normal-to-airfoil flow velocities), the results indicate on a decrease of ~ 10 percent and more in the total energy radiated by a permeable versus an impermeable airfoil. This amounts to a reduction in system sound pressure level of 3 dB and above at pitching flight conditions, where the sound-reducing effect of the seepage dipole pressure becomes dominant. The applicability of Darcy's law to model the effect of material porosity is discussed in light of existing literature.

  11. Airfoil shape optimization using non-traditional optimization technique and its validation

    Directory of Open Access Journals (Sweden)

    R. Mukesh

    2014-07-01

    Full Text Available Computational fluid dynamics (CFD is one of the computer-based solution methods which is more widely employed in aerospace engineering. The computational power and time required to carry out the analysis increase as the fidelity of the analysis increases. Aerodynamic shape optimization has become a vital part of aircraft design in the recent years. Generally if we want to optimize an airfoil we have to describe the airfoil and for that, we need to have at least hundred points of x and y co-ordinates. It is really difficult to optimize airfoils with this large number of co-ordinates. Nowadays many different schemes of parameter sets are used to describe general airfoil such as B-spline, and PARSEC. The main goal of these parameterization schemes is to reduce the number of needed parameters as few as possible while controlling the important aerodynamic features effectively. Here the work has been done on the PARSEC geometry representation method. The objective of this work is to introduce the knowledge of describing general airfoil using twelve parameters by representing its shape as a polynomial function. And also we have introduced the concept of Genetic Algorithm to optimize the aerodynamic characteristics of a general airfoil for specific conditions. A MATLAB program has been developed to implement PARSEC, Panel Technique, and Genetic Algorithm. This program has been tested for a standard NACA 2411 airfoil and optimized to improve its coefficient of lift. Pressure distribution and co-efficient of lift for airfoil geometries have been calculated using the Panel method. The optimized airfoil has improved co-efficient of lift compared to the original one. The optimized airfoil is validated using wind tunnel data.

  12. Unsteady Thick Airfoil Aerodynamics: Experiments, Computation, and Theory

    Science.gov (United States)

    Strangfeld, C.; Rumsey, C. L.; Mueller-Vahl, H.; Greenblatt, D.; Nayeri, C. N.; Paschereit, C. O.

    2015-01-01

    An experimental, computational and theoretical investigation was carried out to study the aerodynamic loads acting on a relatively thick NACA 0018 airfoil when subjected to pitching and surging, individually and synchronously. Both pre-stall and post-stall angles of attack were considered. Experiments were carried out in a dedicated unsteady wind tunnel, with large surge amplitudes, and airfoil loads were estimated by means of unsteady surface mounted pressure measurements. Theoretical predictions were based on Theodorsen's and Isaacs' results as well as on the relatively recent generalizations of van der Wall. Both two- and three-dimensional computations were performed on structured grids employing unsteady Reynolds-averaged Navier-Stokes (URANS). For pure surging at pre-stall angles of attack, the correspondence between experiments and theory was satisfactory; this served as a validation of Isaacs theory. Discrepancies were traced to dynamic trailing-edge separation, even at low angles of attack. Excellent correspondence was found between experiments and theory for airfoil pitching as well as combined pitching and surging; the latter appears to be the first clear validation of van der Wall's theoretical results. Although qualitatively similar to experiment at low angles of attack, two-dimensional URANS computations yielded notable errors in the unsteady load effects of pitching, surging and their synchronous combination. The main reason is believed to be that the URANS equations do not resolve wake vorticity (explicitly modeled in the theory) or the resulting rolled-up un- steady flow structures because high values of eddy viscosity tend to \\smear" the wake. At post-stall angles, three-dimensional computations illustrated the importance of modeling the tunnel side walls.

  13. Unsteady airfoil flows with application to aeroelastic stability

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, Jeppe

    1999-09-01

    The present report describes numerical investigation of two-dimensional unsteady airfoil flows with application to aeroelastic stability. The report is divided in two parts. Part A describes the purely aerodynamic part, while Part B includes the aeroelastic part. In Part A a transition prediction algorithm based on a simplified version of the e{sup n} method is proposed. Laminar Boundary Layer instability data are stored in a database from which stability characteristics can be extracted by interpolation. Input to the database are laminar integral boundary layer parameters. These are computed from an integral boundary layer formulation coupled to a Navier-Stokes flow solver. Five different airfoils are considered at fixed angle of attack, and the flow is computed assuming both fully turbulent and transitional flow and compared with experimental data. Results indicate that using a transition model the drag prediction is improved considerably. Also the lift is slightly improved. At high angles of attack transition will affect leading edge separation which again will affect the overall vortex shedding. If the transition point is not properly predicted this will affect the whole hysteresis curve. The transition model developed in the present work showed more stable predictions compared to the empirical transition model. In Part B a simple three degrees-of-freedom (DOF) structural dynamics model is developed and coupled to the aerodynamics models from Part A. A 2nd order accurate time integration scheme is used to solve the equations of motion. Two airfoils are investigated. The aeroelastic models predict stable conditions well at low angle of attack. But at high angles of attack, and where unstable behaviour is expected, only the Navier-Stokes solver predict correct aeroelastic response. The semi-empirical dynamic stall model does not predict vortex shedding and moment correctly leading to an erroneous aerodynamic damping. (au) 5 tabs.; 55 ills., 52 refs.

  14. Airfoil longitudinal gust response in separated vs. attached flows

    Science.gov (United States)

    Granlund, K.; Monnier, B.; Ol, M.; Williams, D.

    2014-02-01

    Airfoil aerodynamic loads are expected to have quasi-steady, linear dependence on the history of input disturbances, provided that small-amplitude bounds are observed. We explore this assertion for the problem of periodic sinusoidal streamwise gusts, by comparing experiments on nominally 2D airfoils in temporally sinusoidal modulation of freestream speed in a wind tunnel vs. sinusoidal displacement of the airfoil in constant freestream in a water tunnel. In the wind tunnel, there is a streamwise unsteady pressure gradient causing a buoyancy force, while in the water tunnel one must subtract the inertial load of the test article. Both experiments have an added-mass contribution to aerodynamic force. Within measurement resolution, lift and drag, fluctuating and mean, were in good agreement between the two facilities. For incidence angle below static stall, small-disturbance theory was found to be in good agreement with measured lift history, regardless of oscillation frequency. The circulatory component of fluctuating drag was found to be independent of oscillation frequency. For larger incidence angles, there is marked departure between the measured lift history and that predicted from Greenberg's formula. Flow visualization shows coupling between bluff-body shedding and motion-induced shedding, identifiable with lift cancellation or augmentation, depending on the reduced frequency. Isolating the buoyancy effect in the wind tunnel and dynamic tares in the water tunnel, and theoretical calculation of apparent-mass in both cases, we arrive at good agreement in measured circulatory contribution between the two experiments whether the flow is attached or separated substantiating the linear superposition of the various constituents to total lift and drag, and supporting the idea that aerodynamic gust response can legitimately be studied in a steady freestream by oscillating the test article.

  15. Active Control of Separation From the Flap of a Supercritical Airfoil

    Science.gov (United States)

    Melton, LaTunia Pack; Yao, Chung-Sheng; Seifert, Avi

    2006-01-01

    Zero-mass-flux periodic excitation was applied at several regions on a simplified high-lift system to delay the occurrence of flow separation. The NASA Energy Efficient Transport (EET) supercritical airfoil was equipped with a 15% chord simply hinged leading edge flap and a 25% chord simply hinged trailing edge flap. Detailed flow features were measured in an attempt to identify optimal actuator placement. The measurements included steady and unsteady model and tunnel wall pressures, wake surveys, arrays of surface hot-films, flow visualization, and particle image velocimetry (PIV). The current paper describes the application of active separation control at several locations on the deflected trailing edge flap. High frequency (F(+) approximately equal to 10) and low frequency amplitude modulation (F(+) sub AM approximately equal to 1) of the high frequency excitation were used for control. It was noted that the same performance gains were obtained with amplitude modulation and required only 30% of the momentum input required by pure sine excitation.

  16. 14 CFR 27.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 27... Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must be able to...

  17. 14 CFR 29.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 29... § 29.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...

  18. 14 CFR 25.1461 - Equipment containing high energy rotors.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Equipment containing high energy rotors. 25... § 25.1461 Equipment containing high energy rotors. (a) Equipment containing high energy rotors must meet paragraph (b), (c), or (d) of this section. (b) High energy rotors contained in equipment must...

  19. 14 CFR 135.157 - Oxygen equipment requirements.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oxygen equipment requirements. 135.157... Equipment § 135.157 Oxygen equipment requirements. (a) Unpressurized aircraft. No person may operate an unpressurized aircraft at altitudes prescribed in this section unless it is equipped with enough...

  20. 14 CFR 25.1441 - Oxygen equipment and supply.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oxygen equipment and supply. 25.1441... Oxygen equipment and supply. (a) If certification with supplemental oxygen equipment is requested, the equipment must meet the requirements of this section and §§ 25.1443 through 25.1453. (b) The oxygen...

  1. 38 CFR 17.156 - Eligibility for automobile adaptive equipment.

    Science.gov (United States)

    2010-07-01

    ... automobile adaptive equipment. 17.156 Section 17.156 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS MEDICAL Automotive Equipment and Driver Training § 17.156 Eligibility for automobile adaptive equipment. Automobile adaptive equipment may be authorized if the Under Secretary for Health...

  2. Two inviscid computational simulations of separated flow about airfoils

    Science.gov (United States)

    Barnwell, R. W.

    1976-01-01

    Two inviscid computational simulations of separated flow about airfoils are described. The basic computational method is the line relaxation finite-difference method. Viscous separation is approximated with inviscid free-streamline separation. The point of separation is specified, and the pressure in the separation region is calculated. In the first simulation, the empiricism of constant pressure in the separation region is employed. This empiricism is easier to implement with the present method than with singularity methods. In the second simulation, acoustic theory is used to determine the pressure in the separation region. The results of both simulations are compared with experiment.

  3. 47 CFR 36.126 - Circuit equipment-Category 4.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Circuit equipment-Category 4. 36.126 Section 36... Central Office Equipment § 36.126 Circuit equipment—Category 4. (a) For the purpose of this section, the term “Circuit Equipment” encompasses the Radio Systems and Circuit Equipment contained in Accounts...

  4. Preliminary Equipment List

    International Nuclear Information System (INIS)

    The methodology for assigning equipment identifiers and component identifiers for the MGR Site Recommendation or License Application is presented below. Engineering Computer Support (ECS) assigns all equipment and component identifiers and is responsible for entering equipment identifiers into the Plant Design System (PDS) Master Equipment List. A sample report from the PDS Master Equipment List is attached. The attached report is representative of the information that will be provided by the PDS system. Since the equipment list presented is only preliminary, actual equipment numbers are not assigned. It contains information required to maintain control of the equipment and components for MGR important to safety systems. Definitions for the fields that currently exist on the PDS Master Equipment List are given

  5. PROGRAM-K, Transonic Airfoil, Turbine, Compressor Blade Design

    International Nuclear Information System (INIS)

    1 - Description of program or function: PROGRAM K is a design code for transonic airfoils, turbine or compressor blades. 2 - Method of solution: The design program results from the ability to solve the partial differential equations of two-dimensional inviscid gas dynamics and analytic continuation into the domain of two independent complex characteristic coordinates. The domain of integration is mapped conformally onto the unit circle in the plane of one of these coordinates. On the circle it is possible to formulate a boundary value problem for the stream function that is well-posed even in the case of transonic flow. Two boundary value problems are solved by means of the fast Fourier Transform and complex extension. Thus, a procedure is developed for the calculation of an airfoil on which the speed q is prescribed as a function of arc length s. For subsonic flow an exact solution of this non-linear problem is obtained. For the transonic case a shock-less flow results which assumes the assigned subsonic values of the speed q exactly but the resulting supersonic values of speed are near the given values

  6. Flight Tests of a Supersonic Natural Laminar Flow Airfoil

    Science.gov (United States)

    Frederick, Michael A.; Banks, Daniel W.; Garzon, G. A.; Matisheck, J. R.

    2015-01-01

    A flight-test campaign of a supersonic natural laminar flow airfoil has been recently completed. The test surface was an 80-inch (203 cm) chord and 40-inch (102 cm) span article mounted on the centerline store location of an F-15B airplane (McDonnell Douglas Corporation, now The Boeing Company, Chicago, Illinois). The test article was designed with a leading edge sweep of effectively 0 deg to minimize boundary layer crossflow. The test article surface was coated with an insulating material to avoid significant heat transfer to and from the test article structure to maintain a quasi-adiabatic wall. An aircraft-mounted infrared camera system was used to determine boundary layer transition and the extent of laminar flow. The tests were flown up to Mach 2.0 and chord Reynolds numbers in excess of 30 million. The objectives of the tests were to determine the extent of laminar flow at high Reynolds numbers and to determine the sensitivity of the flow to disturbances. Both discrete (trip dots) and 2-D disturbances (forward-facing steps) were tested. A series of oblique shocks, of yet unknown origin, appeared on the surface, which generated sufficient crossflow to affect transition. Despite the unwanted crossflow, the airfoil performed well. The results indicate the sensitivity of the flow to the disturbances, which can translate into manufacturing tolerances, were similar to that of subsonic natural laminar flow wings.

  7. Film cooling air pocket in a closed loop cooled airfoil

    Science.gov (United States)

    Yu, Yufeng Phillip; Itzel, Gary Michael; Osgood, Sarah Jane; Bagepalli, Radhakrishna; Webbon, Waylon Willard; Burdgick, Steven Sebastian

    2002-01-01

    Turbine stator vane segments have radially inner and outer walls with vanes extending between them. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. To provide for air film cooing of select portions of the airfoil outer surface, at least one air pocket is defined on a wall of at least one of the cavities. Each air pocket is substantially closed with respect to the cooling medium in the cavity and cooling air pumped to the air pocket flows through outlet apertures in the wall of the airfoil to cool the same.

  8. Evaluation of Icing Scaling on Swept NACA 0012 Airfoil Models

    Science.gov (United States)

    Tsao, Jen-Ching; Lee, Sam

    2012-01-01

    Icing scaling tests in the NASA Glenn Icing Research Tunnel (IRT) were performed on swept wing models using existing recommended scaling methods that were originally developed for straight wing. Some needed modifications on the stagnation-point local collection efficiency (i.e., beta(sub 0) calculation and the corresponding convective heat transfer coefficient for swept NACA 0012 airfoil models have been studied and reported in 2009, and the correlations will be used in the current study. The reference tests used a 91.4-cm chord, 152.4-cm span, adjustable sweep airfoil model of NACA 0012 profile at velocities of 100 and 150 knot and MVD of 44 and 93 mm. Scale-to-reference model size ratio was 1:2.4. All tests were conducted at 0deg angle of attack (AoA) and 45deg sweep angle. Ice shape comparison results were presented for stagnation-point freezing fractions in the range of 0.4 to 1.0. Preliminary results showed that good scaling was achieved for the conditions test by using the modified scaling methods developed for swept wing icing.

  9. Flight tests of a supersonic natural laminar flow airfoil

    International Nuclear Information System (INIS)

    A flight test campaign of a supersonic natural laminar flow airfoil has been recently completed. The test surface was an 80 inch (203 cm) chord and 40 inch (102 cm) span article mounted on the centerline store location of an F-15B airplane. The test article was designed with a leading edge sweep of effectively 0° to minimize boundary layer crossflow. The test article surface was coated with an insulating material to avoid significant heat transfer to and from the test article structure to maintain a quasi-adiabatic wall. An aircraft-mounted infrared camera system was used to determine boundary layer transition and the extent of laminar flow. The tests were flown up to Mach 2.0 and chord Reynolds numbers in excess of 30 million. The objectives of the tests were to determine the extent of laminar flow at high Reynolds numbers and to determine the sensitivity of the flow to disturbances. Both discrete (trip dots) and 2D disturbances (forward-facing steps) were tested. A series of oblique shocks, of yet unknown origin, appeared on the surface, which generated sufficient crossflow to affect transition. Despite the unwanted crossflow, the airfoil performed well. The results indicate that the sensitivity of the flow to the disturbances, which can translate into manufacturing tolerances, was similar to that of subsonic natural laminar flow wings. (paper)

  10. Uncertainty Quantification for Airfoil Icing using Polynomial Chaos Expansions

    CERN Document Server

    DeGennaro, Anthony M; Martinelli, Luigi

    2014-01-01

    The formation and accretion of ice on the leading edge of a wing can be detrimental to airplane performance. Complicating this reality is the fact that even a small amount of uncertainty in the shape of the accreted ice may result in a large amount of uncertainty in aerodynamic performance metrics (e.g., stall angle of attack). The main focus of this work concerns using the techniques of Polynomial Chaos Expansions (PCE) to quantify icing uncertainty much more quickly than traditional methods (e.g., Monte Carlo). First, we present a brief survey of the literature concerning the physics of wing icing, with the intention of giving a certain amount of intuition for the physical process. Next, we give a brief overview of the background theory of PCE. Finally, we compare the results of Monte Carlo simulations to PCE-based uncertainty quantification for several different airfoil icing scenarios. The results are in good agreement and confirm that PCE methods are much more efficient for the canonical airfoil icing un...

  11. Application of Nontraditional Optimization Techniques for Airfoil Shape Optimization

    Directory of Open Access Journals (Sweden)

    R. Mukesh

    2012-01-01

    Full Text Available The method of optimization algorithms is one of the most important parameters which will strongly influence the fidelity of the solution during an aerodynamic shape optimization problem. Nowadays, various optimization methods, such as genetic algorithm (GA, simulated annealing (SA, and particle swarm optimization (PSO, are more widely employed to solve the aerodynamic shape optimization problems. In addition to the optimization method, the geometry parameterization becomes an important factor to be considered during the aerodynamic shape optimization process. The objective of this work is to introduce the knowledge of describing general airfoil geometry using twelve parameters by representing its shape as a polynomial function and coupling this approach with flow solution and optimization algorithms. An aerodynamic shape optimization problem is formulated for NACA 0012 airfoil and solved using the methods of simulated annealing and genetic algorithm for 5.0 deg angle of attack. The results show that the simulated annealing optimization scheme is more effective in finding the optimum solution among the various possible solutions. It is also found that the SA shows more exploitation characteristics as compared to the GA which is considered to be more effective explorer.

  12. Effects of relative thickness on aerodynamic characteristics of airfoil at a low Reynolds number

    Directory of Open Access Journals (Sweden)

    Ma Dongli

    2015-08-01

    Full Text Available This study focuses on the characteristics of low Reynolds number flow around airfoil of high-altitude unmanned aerial vehicles (HAUAVs cruising at low speed. Numerical simulation on the flows around several representative airfoils is carried out to investigate the low Reynolds number flow. The water tunnel model tests further validate the accuracy and effectiveness of the numerical method. Then the effects of the relative thickness of airfoil on aerodynamic performance are explored, using the above numerical method, by simulating flows around airfoils of different relative thicknesses (12%, 14%, 16%, 18%, as well as different locations of the maximum relative thickness (x/c = 22%, 26%, 30%, 34%, at a low Reynolds number of 5 × 105. Results show that performance of airfoils at low Reynolds number is mainly affected by the laminar separation bubble. On the premise of good stall characteristics, the value of maximum relative thickness should be as small as possible, and the location of the maximum relative thickness ought to be closer to the trailing edge to obtain fine airfoil performance. The numerical method is feasible for the simulation of low Reynolds number flow. The study can help to provide a basis for the design of low Reynolds number airfoil.

  13. Experimental Study of Thin and Thick Airfoils at Low Reynolds Numbers

    Science.gov (United States)

    Durgesh, Vibhav; Garcia, Elifalet; Johari, Hamid

    2015-11-01

    A recent surge in applications of unmanned air vehicles in various fields has led to increased interest in understanding the characteristics of airfoils at Reynolds number regime ~104. At these low Re numbers, aerodynamics of an airfoil is influenced by laminar separation and its possible reattachment, which is in contrast to airfoil behavior at high Re numbers. This study focused on comparing the load characteristics of symmetric, thin (NACA-0009) and thick (NACA-0021) airfoils at low Re numbers ~2 - 4 × 104, and angles of attack between 2° to 12°, along with simultaneous flow visualization. The experiments were performed in a low speed flow visualization water tunnel facility, and two-component Laser Doppler Velocimetry was used to quantify the inflow conditions and turbulence intensity. A high precision force/torque transducer was used for the load measurements, while hydrogen bubble technique was used for flow visualization on the suction side of the airfoils. The presentation will discuss the correlation between observed flow structures and instantaneous load on the airfoils, as well as the aerodynamic load characteristics of thin and thick airfoils at low Re numbers.

  14. Validation of the CQU-DTU-LN1 series of airfoils

    International Nuclear Information System (INIS)

    The CQU-DTU-LN1 series of airfoils were designed with an objective of high lift and low noise emission. In the design process, the aerodynamic performance is obtained using XFOIL while noise emission is obtained with the BPM model. In this paper we present some validations of the designed CQU-DTU-LN118 airfoil by using wind tunnel measurements in the acoustic wind tunnel located at Virginia Tech and numerical computations with the inhouse Q3uic and EllipSys 2D/3D codes. To show the superiority of the new airfoils, comparisons with a NACA64618 airfoil are made. For the aerodynamic features, the designed Cl and Cl/Cd agrees well with the experiment and are in general higher than those of the NACA airfoil. For the acoustic features, the noise emission of the LN118 airfoil is compared with the acoustic measurements and that of the NACA airfoil. Comparisons show that the BPM model can predict correctly the noise changes

  15. Reynolds Number Effects Investigation of Supercritical Airfoil Based on EFD and CFD

    Directory of Open Access Journals (Sweden)

    Da-Wei Liu

    2013-12-01

    Full Text Available This study aimed to investigate the transonic Reynolds number effects of supercritical airfoil by EFD and CFD method. An experiment was conducted in NF-6 wind tunnel, to obtain the pressure distribution and aerodynamic coefficients of a typical supercritical airfoil through pressure measuring, with Reynolds numbers varied from 3.5×106 to 1.0×107 per airfoil chord, Mach numbers from 0.6 to 0.8, angles of attack from 0° to 8°. Also, flows over the supercritical airfoil were numerically studied; the two-dimensional Navier-Stokes equations were solved with structure grids by utilizing the Spalart-Allmaras (S-A turbulence model, with Reynolds numbers varied from 2.0×106 to 50×10 6 per airfoil chord and Mach numbers from 0.6 to 0.8. Computational results compared well with experimental results. It is shown that the upper surface pressure distribution of supercritical airfoil including the location and intensity of shock wave and trailing-edge pressure coefficient, changed apparently with variable Reynolds numbers, when shock-induced trailing-edge separation existed. It is also noticed that the lift coefficient increased, drag and pitching moment coefficient decreased as Reynolds number increasing. Results implied that Reynolds number effects should be considered during the early designing stage and optimization of large aircrafts applied supercritical airfoil.

  16. Unsteady 2D potential-flow forces and a thin variable geometry airfoil undergoing arbitrary motion

    Energy Technology Data Exchange (ETDEWEB)

    Gaunaa, M.

    2006-07-15

    In this report analytical expressions for the unsteady 2D force distribution on a variable geometry airfoil undergoing arbitrary motion are derived under the assumption of incompressible, irrotational, inviscid flow. The airfoil is represented by its camberline as in classic thin-airfoil theory, and the deflection of the airfoil is given by superposition of chordwise deflection mode shapes. It is shown from the expressions for the forces, that the influence from the shed vorticity in the wake is described by the same time-lag for all chordwise positions on the airfoil. This time-lag term can be approximated using an indicial function approach, making the practical calculation of the aerodynamic response numerically very efficient by use of Duhamel superposition. Furthermore, the indicial function expressions for the time-lag terms are formulated in their equivalent state-space form, allowing for use of the present theory in problems employing the eigenvalue approach, such as stability analysis. The analytical expressions for the forces simplify to all previously known steady and unsteady thin-airfoil solutions. Apart from the obvious applications within active load control/reduction, the current theory can be used for various applications which up to now have been possible only using much more computational costly methods. The propulsive performance of a soft heaving propulsor, and the influence of airfoil camberline elasticity on the flutter limit are two computational examples given in the report that highlight this feature. (au)

  17. Parametric analyses for synthetic jet control on separation and stall over rotor airfoil

    Directory of Open Access Journals (Sweden)

    Zhao Guoqing

    2014-10-01

    Full Text Available Numerical simulations are performed to investigate the effects of synthetic jet control on separation and stall over rotor airfoils. The preconditioned and unsteady Reynolds-averaged Navier–Stokes equations coupled with a k − ω shear stream transport turbulence model are employed to accomplish the flowfield simulation of rotor airfoils under jet control. Additionally, a velocity boundary condition modeled by a sinusoidal function is developed to fulfill the perturbation effect of periodic jets. The validity of the present CFD procedure is evaluated by the simulated results of an isolated synthetic jet and the jet control case for airfoil NACA0015. Then, parametric analyses are conducted specifically for an OA213 rotor airfoil to investigate the effects of jet parameters (forcing frequency, jet location and momentum coefficient, jet direction, and distribution of jet arrays on the control effect of the aerodynamic characteristics of a rotor airfoil. Preliminary results indicate that the efficiency of jet control can be improved with specific frequencies (the best lift-drag ratio at F+ = 2.0 and jet angles (40° or 75° when the jets are located near the separation point of the rotor airfoil. Furthermore, as a result of a suitable combination of jet arrays, the lift coefficient of the airfoil can be improved by nearly 100%, and the corresponding drag coefficient decreased by 26.5% in comparison with the single point control case.

  18. Airfoil-Shaped Fluid Flow Tool for Use in Making Differential Measurements

    Science.gov (United States)

    England, John Dwight (Inventor); Kelley, Anthony R. (Inventor); Cronise, Raymond J. (Inventor)

    2014-01-01

    A fluid flow tool includes an airfoil structure and a support arm. The airfoil structure's high-pressure side and low-pressure side are positioned in a conduit by the support arm coupled to the conduit. The high-pressure and low-pressure sides substantially face opposing walls of the conduit. At least one measurement port is formed in the airfoil structure at each of its high-pressure side and low-pressure side. A first manifold, formed in the airfoil structure and in fluid communication with each measurement port so-formed at the high-pressure side, extends through the airfoil structure and support arm to terminate and be accessible at the exterior wall of the conduit. A second manifold, formed in the airfoil structure and in fluid communication with each measurement port so-formed at the low-pressure side, extends through the airfoil structure and support arm to terminate and be accessible at the exterior wall of the conduit.

  19. The acoustics and unsteady wall pressure of a circulation control airfoil

    Science.gov (United States)

    Silver, Jonathan C.

    A Circulation Control (CC) airfoil uses a wall jet exiting onto a rounded trailing edge to generate lift via the Coanda effect. The aerodynamics of the CC airfoil have been studied extensively. The acoustics of the airfoil are, however, much less understood. The primary goal of the present work was to study the radiated sound and unsteady surface pressures of a CC airfoil. The focus of this work can be divided up into three main categories: characterizing the unsteady surface pressures, characterizing the radiated sound, and understanding the acoustics from surface pressures. The present work is the first to present the unsteady surface pressures from the trailing edge cylinder of a circulation control airfoil. The auto-spectral density of the unsteady surface pressures at various locations around the trailing edge are presented over a wide range of the jets momentum coefficient. Coherence of pressure and length scales were computed and presented. Single microphone measurements were made at a range of angles for a fixed observer distance in the far field. Spectra are presented for select angles to show the directivity of the airfoil's radiated sound. Predictions of the acoustics were made from unsteady surface pressures via Howe's curvature noise model and a modified Curle's analogy. A summary of the current understanding of the acoustics from a CC airfoil is given along with suggestions for future work.

  20. 47 CFR 32.2232 - Circuit equipment.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Circuit equipment. 32.2232 Section 32.2232... FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2232 Circuit equipment... which is used for the amplification, modulation, regeneration, circuit patching, balancing or control...

  1. 49 CFR 195.262 - Pumping equipment.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Pumping equipment. 195.262 Section 195.262... PIPELINE Construction § 195.262 Pumping equipment. (a) Adequate ventilation must be provided in pump... warn of the presence of hazardous vapors in the pumping station building. (b) The following must...

  2. 49 CFR 374.313 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Equipment. 374.313 Section 374.313 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION... of Intercity Motor Common Carrier Passenger Service § 374.313 Equipment. (a) Temperature control....

  3. 32 CFR 37.1280 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 1 2010-07-01 2010-07-01 false Equipment. 37.1280 Section 37.1280 National Defense Department of Defense OFFICE OF THE SECRETARY OF DEFENSE DoD GRANT AND AGREEMENT REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms Used in This Part § 37.1280 Equipment....

  4. 23 CFR 1200.21 - Equipment.

    Science.gov (United States)

    2010-04-01

    ... 402 program, in the absence of which the State shall follow the applicable procedures in 49 CFR part... 23 Highways 1 2010-04-01 2010-04-01 false Equipment. 1200.21 Section 1200.21 Highways NATIONAL... Implementation and Management of the Highway Safety Program § 1200.21 Equipment. (a) Title. Except as provided...

  5. 14 CFR 398.4 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Equipment. 398.4 Section 398.4 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) POLICY STATEMENTS GUIDELINES FOR INDIVIDUAL DETERMINATIONS OF BASIC ESSENTIAL AIR SERVICE § 398.4 Equipment....

  6. 10 CFR 603.1255 - Equipment.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Equipment. 603.1255 Section 603.1255 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms Used in this Part § 603.1255 Equipment. Tangible property, other than real property, that has a useful life...

  7. 46 CFR 168.15-20 - Equipment.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Equipment. 168.15-20 Section 168.15-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS Accommodations § 168.15-20 Equipment. (a) Each person shall have a separate berth and not more than 1 berth...

  8. 29 CFR 1910.430 - Equipment.

    Science.gov (United States)

    2010-07-01

    ... accordance with the applicable provisions of 29 CFR 1910.101 and 1910.169 through 1910.171. (2) Be stored in... 29 Labor 5 2010-07-01 2010-07-01 false Equipment. 1910.430 Section 1910.430 Labor Regulations... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Commercial Diving Operations Equipment Procedures and...

  9. 50 CFR 27.72 - Audio equipment.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Audio equipment. 27.72 Section 27.72 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) THE... Audio equipment. The operation or use of audio devices including radios, recording and playback...

  10. Wind-tunnel investigation of an NACA 23012 airfoil with 30 percent-chord venetian-blind flaps

    Science.gov (United States)

    Rogallo, F M; Spano, Bartholomew S

    1942-01-01

    Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a NACA 23012 airfoil with 30-percent-chord venetian-blind flaps having one, two, three, and four slats of Clark y section. The three-slat arrangements was aerodynamically the best of those tested but showed practically no improvement over the comparable arrangement used in the preliminary tests published in NACA Technical Report No. 689. The multiple-slat flaps gave slightly higher lift coefficients than the one-slat (Fowler) flap but gave considerably greater pitching-moment coefficients. An analysis of test data indicates that substitution of a thicker and more cambered section for the Clark y slats should improve the aerodynamic and the structural characteristics of the venetian-blind flap.

  11. The effect of acoustic forcing on an airfoil tonal noise mechanism.

    Science.gov (United States)

    Schumacher, Karn L; Doolan, Con J; Kelso, Richard M

    2014-08-01

    The response of the boundary layer over an airfoil with cavity to external acoustic forcing, across a sweep of frequencies, was measured. The boundary layer downstream of the cavity trailing edge was found to respond strongly and selectively at the natural airfoil tonal frequencies. This is considered to be due to enhanced feedback. However, the shear layer upstream of the cavity trailing edge did not respond at these frequencies. These findings confirm that an aeroacoustic feedback loop exists between the airfoil trailing edge and a location near the cavity trailing edge. PMID:25096150

  12. Dynamic stall modeling and correlation with experimental data on airfoils and rotors

    Science.gov (United States)

    Carlson, R. G.; Blackwell, R. H.; Commerford, G. L.; Mirick, P. H.

    1974-01-01

    Two methods for modeling dynamic stall have been developed. The alpha, A, B method generates lift and pitching moments as functions of angle of attack and its first two time derivatives. The coefficients are derived from experimental data for oscillating airfoils. The Time Delay Method generates the coefficients from steady state airfoil characteristics and an associated time delay in stall beyond the steady state stall angle. Correlation with three types of test data shows that the alpha, A, B method is somewhat better for use in predicting helicopter rotor response in forward flight. Correlation with lift and moment hysteresis loops generated for oscillating airfoils was good for both models.

  13. Fluid mechanics mechanisms in the stall process of airfoils for helicopters

    Science.gov (United States)

    Young, W. H., Jr.

    1981-01-01

    Phenomena that control the flow during the stall portion of a dynamic stall cycle are analyzed, and their effect on blade motion is outlined. Four mechanisms by which dynamic stall may be initiated are identified: (1) bursting of the separation bubble, (2) flow reversal in the turbulent boundary layer on the airfoil upper surface, (3) shock wave-boundary layer interaction behind the airfoil crest, and (4) acoustic wave propagation below the airfoil. The fluid mechanics that contribute to the identified flow phenomena are summarized, and the usefulness of a model that incorporates the required fluid mechanics mechanisms is discussed.

  14. Potential flow around two-dimensional airfoils using a singular integral method

    Science.gov (United States)

    Nguyen, Yves; Wilson, Dennis

    1987-01-01

    The problem of potential flow around two-dimensional airfoils is solved by using a new singular integral method. The potential flow equations for incompressible potential flow are written in a singular integral equation. The equation is solved at N collocation points on the airfoil surface. A unique feature of this method is that the airfoil geometry is specified as an independent variable in the exact integral equation. Compared to other numerical methods, the present calculation procedure is much simpler and gives remarkable accuracy for many body shapes. An advantage of the present method is that it allows the inverse design calculation and the results are extremely accurate.

  15. Experimental Investigation on the Aerodynamic Performance of NLF-0414 Iced-Airfoil

    OpenAIRE

    abbas ebrahimi; majid hajipour; Hossein Hasheminasa

    2016-01-01

    Icing phenomenon on a natural laminar flow airfoil (NLF-0414) has been experimentally investigated. Double horn glaze ice geometry which was acquired during a 15 minutes spray time at-2.23℃ with liquid water content and a median volumetric diameter of 1.0 g/m3 and 20 μm, has been extracted from database of NASA Lewis Research Center. Pressure distribution over airfoil surfacewas evaluated at angles of attack between -2 to 6 degrees for both iced and clean airfoils. Aerodynamics performance de...

  16. Airfoil-based piezoelectric energy harvesting by exploiting the pseudoelastic hysteresis of shape memory alloy springs

    Science.gov (United States)

    de Sousa, Vagner Candido; De Marqui Junior, Carlos

    2015-12-01

    The modeling and analysis of an electromechanically coupled typical aeroelastic section with shape memory alloy springs for wind energy harvesting is addressed in this paper. An airfoil with two-degrees-of-freedom, namely pitch and plunge, is considered and piezoelectric coupling is added to the plunge degree-of-freedom. A load resistance is assumed in the electrical domain of the problem in order to estimate the electrical power output. Shape memory alloy coil springs are modeled in the pitch degree-of-freedom of the typical section. A nickel-titanium alloy that exhibits pseudoelasticity at room temperature is assumed. The constitutive model for the shape memory alloy is based on classical phenomenological models. The unsteady aerodynamic loads are obtained by Jones’ approximation to Wagner’s indicial function. The resulting nonlinear electroaeroelastic model is cast into a state-space representation and solved with a Runge-Kutta method. The effects of preload values of the shape memory springs and resistive power generation on the aeroelastic behavior of the wind energy harvester are investigated at the flutter boundary and in a post-flutter regime. The nonlinear kinetics of the austenite-to-martensite phase transformation changes the typical linear flutter behavior to stable limit-cycle oscillations over a range of airflow speeds. Such nonlinear aeroelastic behavior introduced by the hysteretic behavior of the SMA springs provides an important source of persistent electrical power.

  17. Fatigue behavior of vertical axis wind turbine airfoils with two weld configurations

    Science.gov (United States)

    Mitchell, M. R.; Murphy, A. R.

    1989-10-01

    A series of narrowband, pseudo-random cyclic fatigue tests on sections of 6063-T651 aluminum, Darrius-type, vertical axis wind turbine (VAWT) airfoils were performed. A load member was designed and constructed that was mounted within the frame of a rigid 200-kip servohydraulic, closed-loop test system to hold the VAWT section and permit cantilever bending along the shear centerline of the beam. A computer program was developed to synthesize a narrow band, pseudo-random load history with fixed root mean square (RMS) stress levels at a given bandwidth and central frequency. Six specimens each of two different weld configurations at the flange mounting plate were tested at several RMS stress levels with failure defined as visual observation of a 3 inch long crack in the VAWT. In order to test at as great a frequency as possible, a 20-kip hydraulic ram with a 10 GPM servovalve was employed with a 20 GPM pump. Tests were performed from 2 to 1.3 ksi RMS on the two-weld configurations. The conclusions are obvious that the fillet weld design is far superior to the butt weld design in the range of variables used in this program.

  18. Mobile Equipment Expands Inventory.

    Science.gov (United States)

    McGough, Robert L.; And Others

    1978-01-01

    Describes the Mobile Equipment Modules (MEM) system in Duluth, Minnesota. MEM is a way to hold down costs and increase learning opportunities by consolidating purchases of expensive shop equipment within the school district, grouping the equipment in modules, and scheduling and moving it from school to school as needed. (MF)

  19. Electrical equipment qualification

    International Nuclear Information System (INIS)

    Electrical equipment qualification research programs being carried out by CEA, JAERI, and Sandia Laboratories are discussed. Objectives of the program are: (1) assessment of accident simulation methods for electrical equipment qualification testing; lower coarse (2) evaluation of equipment aging and accelerated aging methods; (3) determine radiation dose spectrum to electrical equipment and assess simulation methods for qualification; (4) identify inadequacies in electrical equipment qualification procedures and standards and potential failure modes; and (5) provide data for verifying and improving standards, rules and regulatory guides

  20. Overview of two-dimensional airfoil research at Ames Research Center

    Science.gov (United States)

    Chapman, G. T.

    1979-01-01

    The five basic elements of the two dimensional airfoil research program at Ames Research Center are illustrated. These elements are experimental, theoretical (including computational), validation, design optimization, and industry interaction. Each area is briefly discussed.

  1. Numerical Investigation of Flow Control by Suction and Injection on a Subsonic Airfoil

    Directory of Open Access Journals (Sweden)

    M. H. Shojaefard

    2005-01-01

    Full Text Available This study presents a numerical study concerning flow control by suction and injection. The case studied is the flow field over a subsonic airfoil with four suction and injection slots on the suction side of the airfoil. Five different angles of attack, 0, 5, 10, 13.3 and 20 with the Mach number of 0.15 are studied. Three cases are studied in each angle of attack. The three cases are airfoil with surface suction, surface injection and the base airfoil. A commercial CFD code, the FLUENT, is used in this study. The effect of suction and injection on aerodynamic coefficients is investigated. The results show that the surface suction can significantly increase the lift coefficient. The injection decreases the skin friction.

  2. Unsteady 2D potential-flow forces on a thin variable geometry airfoil undergoing arbitrary motion

    DEFF Research Database (Denmark)

    Gaunaa, M.

    2006-01-01

    In this report analytical expressions for the unsteady 2D force distribution on a variable geometry airfoil undergoing arbitrary motion are derived under the assumption of incompressible, irrotational, inviscid flow. The airfoil is represented by itscamberline as in classic thin-airfoil theory...... using an indicial function approach, making the practical calculation of the aerodynamic response numerically very efficient by use ofDuhamel superposition. Furthermore, the indicial function expressions for the time-lag terms are formulated in their equivalent state-space form, allowing for use...... of the present theory in problems employing the eigenvalue approach, such as stabilityanalysis. The analytical expressions for the forces simplify to all previously known steady and unsteady thin-airfoil solutions. Apart from the obvious applications within active load control/reduction, the current theory can...

  3. Unsteady two-dimensional potential-flow model for thin variable geometry airfoils

    DEFF Research Database (Denmark)

    Gaunaa, Mac

    2010-01-01

    In the present work, analytical expressions for distributed and integral unsteady two-dimensional forces on a variable geometry airfoil undergoing arbitrary motion are derived under the assumption of incompressible, irrotational, inviscid flow. The airfoil is represented by its camber line...... on the airfoil. This time-lag term can be approximated using an indicial function approach, making the practical calculation of the aerodynamic response numerically very efficient by use of Duhamel superposition. Furthermore, the indicial function expressions for the time-lag terms are formulated...... in their equivalent state-space form, allowing for use of the present theory in problems employing the eigenvalue approach, such as stability analysis. The analytical expressions for the integral forces can be reduced to Munk's steady and Theodorsen's unsteady results for thin airfoils, and numerical evaluation shows...

  4. Airfoil Selection of MAV (Miniature Air Vehicle for Low Reynolds Number

    Directory of Open Access Journals (Sweden)

    Mayur S. Marathe

    2013-12-01

    Full Text Available This paper discusses issues and practical requirements of Airfoil for MAV. Here considering the MAV which travel with the speed range between 9-20 m/s. The Airfoil which is been selected on various criteria, i.e. - stable flight, cover maximum distance with minimum force. So here the NACA 2204 is been selected for MAV. The Fluent analysis is done on the airfoil for lift to drag ratio. These MAV are having some purpose i.e.:- they can be use as a spy in enemy area, inspection of hazardous area, where human resource can’t reach. Aerodynamic performance and stability should be considered in the context of the airfoil structural integrity. Particular attention should be paid to the unsteady nature of the flow.

  5. Application of an upwind Navier-Stokes code to two-dimensional transonic airfoil flow

    International Nuclear Information System (INIS)

    An upwind-biased implicit approximate factorization Navier-Stokes algorithm is applied to a variety of steady transonic airfoil cases, using the NACA 0012, RAE 2822, and Jones supercritical airfoils. The thin-layer form of the compressible Navier-Stokes equations is used. Both the CYBER 205 and CRAY 2 supercomputers are utilized, with average computational speeds of about 18 and 16 microsec/gridpoint/iteration, respectively. Lift curves, drag polars, and variations in drag coefficient with Mach number are determined for the NACA 0012 and Jones supercritical airfoils. Also, several cases are computed for comparison with experiment. The effect of grid density and grid extent on a typical turbulent airfoil solution is shown. An algebraic eddy-viscosity turbulence model is used for all of the computations. 10 references

  6. Research on Aerodynamic Performance of an Wind Turbine Airfoil With Leading Edge Ice

    Directory of Open Access Journals (Sweden)

    Fu Jie

    2013-12-01

    Full Text Available The performance of wind turbine was influenced by the environment. Among them, airfoil with leading edge ice has a great effect on the changes of aerodynamic performance. This study calculated the performance of an wind tubine airfoil at two iced shape model by CFD simulation using LES. LES in various models has been developed to simulate turbulent flows, especially to separated flows. In this investigation, 2D LES has been used to simulate flow past a wind turbine airfoil with leading edge ice which is a classical separated flow. The results show that flow structure is more complex with abundant whirlpools signifying violent turbulence when airfoil with ice and leads to poorer performance of wind turbine.

  7. Modeling the Aerodynamic Lift Produced by Oscillating Airfoils at Low Reynolds Number

    CERN Document Server

    Khalid, Muhammad Saif Ullah

    2015-01-01

    For present study, setting Strouhal Number (St) as control parameter, numerical simulations for flow past oscillating NACA-0012 airfoil at 1,000 Reynolds Numbers (Re) are performed. Temporal profiles of unsteady forces; lift and thrust, and their spectral analysis clearly indicate the solution to be a period-1 attractor for low Strouhal numbers. This study reveals that aerodynamic forces produced by plunging airfoil are independent of initial kinematic conditions of airfoil that proves the existence of limit cycle. Frequencies present in the oscillating lift force are composed of fundamental (fs), even and odd harmonics (3fs) at higher Strouhal numbers. Using numerical simulations, shedding frequencies (f_s) were observed to be nearly equal to the excitation frequencies in all the cases. Unsteady lift force generated due to the plunging airfoil is modeled by modified van der Pol oscillator. Using method of multiple scales and spectral analysis of steady-state CFD solutions, frequencies and damping terms in th...

  8. Parallel numerical simulation of oscillating airfoil NACA0015 in the channel due to flutter instability

    Directory of Open Access Journals (Sweden)

    Řidký Václav

    2014-03-01

    Full Text Available The work is devoted to 3D and 2D parallel numerical computation of pressure and velocity fields around an elastically supported airfoil self-oscillating due to interaction with the airflow. Numerical solution is computed in the OpenFOAM package, an open-source software package based on finite volume method. Movement of airfoil is described by translation and rotation, identified from experimental data. A new boundary condition for the 2DOF motion of the airfoil was implemented. The results of numerical simulations (velocity are compared with data measured in a wind tunnel, where a physical model of NACA0015 airfoil was mounted and tuned to exhibit the flutter instability. The experimental results were obtained previously in the Institute of Thermomechanics by interferographic measurements in a subsonic wind tunnel in Nový Knín.

  9. Effect of a round airfoil nose on leading-edge suction

    Science.gov (United States)

    Lan, C. Edward; Su, Ingchung

    1987-01-01

    Kulfan (1979) assumed that the angle of attack for initial vortex separation on a slender wing with rounded leading edges could be obtained by equating the leading-edge suction (LES) and nose drag coefficients. In the present study, this assumption is examined and is shown to predict reasonably well the initial angle of attack at which laminar separation occurs near the airfoil nose. However, the assumption is shown to be slightly less accurate for thick or cambered airfoils. Attainable LES estimated by Kulfan's method seemed to agree well with that obtained from an airfoil aerodynamics code and experimental data on a NACA 64A009 airfoil at M = 0.4 and Re = 0.86 x 10 to the 6th.

  10. Space Heating Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, Kevin D.

    1998-01-01

    The performance evaluation of space heating equipment for a geothermal application is generally considered from either of two perspectives: (a) selecting equipment for installation in new construction, or (b) evaluating the performance and retrofit requirements of an existing system. With regard to new construction, the procedure is relatively straightforward. Once the heating requirements are determined, the process need only involve the selection of appropriately sized hot water heating equipment based on the available water temperature. It is important to remember that space heating equipment for geothermal applications is the same equipment used in non-geothermal applications. What makes geothermal applications unique is that the equipment is generally applied at temperatures and flow rates that depart significantly from traditional heating system design. This chapter presents general considerations for the performance of heating equipment at non-standard temperature and flow conditions, retrofit of existing systems, and aspects of domestic hot water heating.

  11. FLOWS AROUND TWO AIRFOILS PERFORMING FLING AND SUBSEQUENT TRANSLATION AND TRANSLATION AND SUBSEQUENT CLAP

    Institute of Scientific and Technical Information of China (English)

    孙茂; 于鑫

    2003-01-01

    The aerodynamic forces and flow structures of two airfoils performing "fling and subsequent translation" and "translation and subsequent clap" are studied by numerically solving the Navier-Stokes equations in moving overset grids. These motions are relevant to the flight of very small insects. The Reynolds number, based on the airfoil chord length c and the translation velocity U, is 17. It is shown that: (1) For two airfoils performing fling and subsequent translation, a large lift is generated both in the fling phase and in the early part of the translation phase. During the fling phase,a pair of leading edge vortices of large strength is generated; the generation of the vortex pair in a short period results in a large time rate of change of fluid impulse, which explains the large lift in this period. During the early part of the translation, the two leading edge vortices move with the airfoils;the relative movement of the vortices also results in a large time rate of change of fluid impulse, which explains the large lift in this part of motion. (In the later part of the translation, the vorticity in the vortices is diffused and convected into the wake.) The time averaged lift coeffcient is approximately 2.4 times as large as that of a single airfoil performing a similar motion. (2) For two airfoils performing translation and subsequent clap, a large lift is generated in the clap phase. During the clap, a pair of trailing edge vortices of large strength are generated; again, the generation of the vortex pair in a short period (which results in a large timerate of change of fluid impulse) is responsible for the large lift in this period. The time averaged lift coefficient is approximately 1.6 times as large as that of a single airfoil performing a similar motion. (3) When the initial distance between the airfoils (in the case of clap, the final distance between the airfoils) varies from 0.1 to 0.2c, the lift on an airfoil decreases only slightly but the torque

  12. Renewal of radiological equipment.

    Science.gov (United States)

    2014-10-01

    In this century, medical imaging is at the heart of medical practice. Besides providing fast and accurate diagnosis, advances in radiology equipment offer new and previously non-existing options for treatment guidance with quite low morbidity, resulting in the improvement of health outcomes and quality of life for the patients. Although rapid technological development created new medical imaging modalities and methods, the same progress speed resulted in accelerated technical and functional obsolescence of the same medical imaging equipment, consequently creating a need for renewal. Older equipment has a high risk of failures and breakdowns, which might cause delays in diagnosis and treatment of the patient, and safety problems both for the patient and the medical staff. The European Society of Radiology is promoting the use of up-to-date equipment, especially in the context of the EuroSafe Imaging Campaign, as the use of up-to-date equipment will improve quality and safety in medical imaging. Every healthcare institution or authority should have a plan for medical imaging equipment upgrade or renewal. This plan should look forward a minimum of 5 years, with annual updates. Teaching points • Radiological equipment has a definite life cycle span, resulting in unavoidable breakdown and decrease or loss of image quality which renders equipment useless after a certain time period.• Equipment older than 10 years is no longer state-of-the art equipment and replacement is essential. Operating costs of older equipment will be high when compared with new equipment, and sometimes maintenance will be impossible if no spare parts are available.• Older equipment has a high risk of failure and breakdown, causing delays in diagnosis and treatment of the patient and safety problems both for the patient and the medical staff.• Every healthcare institution or authority should have a plan for medical imaging equipment upgrade or replacement. This plan should look forward a

  13. A strong viscous–inviscid interaction model for rotating airfoils

    DEFF Research Database (Denmark)

    Ramos García, Néstor; Sørensen, Jens Nørkær; Shen, Wen Zhong

    2014-01-01

    viscous and inviscid parts. The inviscid part is modeled by a 2D panel method, and the viscous part is modeled by solving the integral form of the laminar and turbulent boundary-layer equations with extension for 3D rotational effects. Laminar-to-turbulent transition is either forced by employing a...... version, a parametric study on rotational effects induced by the Coriolis and centrifugal forces in the boundary-layer equations shows that the effects of rotation are to decrease the growth of the boundary-layer and delay the onset of separation, hence increasing the lift coefficient slightly while......Two-dimensional (2D) and quasi-three dimensional (3D), steady and unsteady, viscous–inviscid interactive codes capable of predicting the aerodynamic behavior of wind turbine airfoils are presented. The model is based on a viscous–inviscid interaction technique using strong coupling between the...

  14. Optimal Control of Airfoil Flow Separation using Fluidic Excitation

    Science.gov (United States)

    Shahrabi, Arireza F.

    This thesis deals with the control of flow separation around a symmetric airfoils with the aid of multiple synthetic jet actuators (SJAs). CFD simulation methods have been implemented to uncover the flow separation regimes and associated properties such as frequencies and momentum ratio. In the first part of the study, the SJA was studied thoroughly. Large Eddy Simulations (LES) were performed for one individual cavity; the time history of SJA of the outlet velocity profile and the net momentum imparted to the flow were analyzed. The studied SJA is asymmetrical and operates with the aid of a piezoelectric (PZT) ceramic circular plate actuator. A three-dimensional mesh for the computational domain of the SJA and the surrounding volume was developed and was used to evaluate the details of the airflow conditions inside the SJA as well as at the outlet. The vibration of the PZT ceramic actuator was used as a boundary condition in the computational model to drive the SJA. Particular attention was given to developing a predictive model of the SJA outlet velocity. Results showed that the SJA velocity output is correlated to the PZT ceramic plate vibration, especially for the first frequency mode. SJAs are a particular class of zero net mass flux (ZNMF) fluidic devices with net imparted momentum to the flow. The net momentum imparted to the flow in the separated region is such that positive enhancement during AFC operations is achieved. Flows around the NACA 0015 airfoil were simulated for a range of operating conditions. Attention was given to the active open and closed loop control solutions for an airfoil with SJA at different angles of attack and flap angles. A large number of simulations using RANS & LES models were performed to study the effects of the momentum ratio (Cμ) in the range of 0 to 11% and of the non-dimensional frequency, F+, in the range of 0 to 2 for the control of flow separation at a practical angle of attack and flap angle. The optimum value of C

  15. Airfoil computations using the gamma-Retheta model; Wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Niels N.

    2009-05-15

    The present work addresses the validation of the implementation of the Menter, Langtry et al. gamma-theta correlation based transition model [1, 2, 3] in the EllipSys2D code. Firstly the 2. order of accuracy of the code is verified using a grid refinement study for laminar, turbulent and transitional computations. Based on this, an estimate of the error in the computations is determined to be approximately one percent in the attached region. Following the verification of the implemented model, the model is applied to four airfoils, NACA64-018, NACA64-218, NACA64-418 and NACA64-618 and the results are compared to measurements [4] and computations using the Xfoil code by Drela et al. [5]. In the linear pre stall region good agreement is observed both for lift and drag, while differences to both measurements and Xfoil computations are observed in stalled conditions. (au)

  16. SPIV study of passive flow control on a WT airfoil

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Hansen, Martin Otto Laver; Meyer, Knud Erik; Fuglsang, Peter

    free stream velocity U=15 m/s. The objective was to investigate the flow structures induced by and separation controlling behavior of vortex generators on the airfoil. The experimental results show strong separation of the uncontrolled flow whereas an intermittent behavior appears for the controlled...... controlled flow, the observed vortex structures generated by the devices are similar to those found in studies at lower Reynolds numbers. Further, mixing close to the wall, transferring high momentum fluid into the near wall region, is seen. The hypothesis of intermittent fluctuations in the boundary layer......Stereoscopic Particle Image Velocimetry (SPIV) measurements investigating the effect of vortex generators (VGs) on the flow near stall have been carried out in the purpose built LM Glasfiber wind tunnel on a DU 91-W2-250 profile. Measurements have been conducted at Re=0.9*10^6, corresponding to...

  17. Compliance effects on dynamically pitching wind turbine airfoils

    Science.gov (United States)

    Magstadt, Andrew S.

    The effects of elastic compliance in dynamically pitching wind turbine blades have been investigated. A numerical model guided wind tunnel testing, which used unsteady surface pressure measurements and phase-locked Particle Imaging Velocimetry to gather aerodynamic information. Using a torsionally compliant member, aeroelastic effects on the unsteady aerodynamics were compared against the results from a corresponding rigidly pitching airfoil to isolate the effects of compliance. The novel experimental apparatus and data acquisition techniques developed at the University of Wyoming showed that the presence of compliance can alter flow-field structures and increase dynamic loading. The high sensitivity of this nonlinear system suggests the formation of fluid-structure instabilities in large-scale turbines and demonstrates the potential for aerodynamic control as a means to mitigate adverse loading effects and improve wind turbine efficiency.

  18. Dynamic stall on a pitching and surging airfoil

    Science.gov (United States)

    Dunne, Reeve; McKeon, Beverley J.

    2015-08-01

    Vertical axis wind turbine blades undergo dynamic stall due to the large angle of attack variation they experience during a turbine rotation. The flow over a single blade was modeled using a sinusoidally pitching and surging airfoil in a non-rotating frame with a constant freestream flow at a mean chord Reynolds number of . Two-dimensional, time-resolved velocity fields were acquired using particle image velocimetry. Vorticity contours were used to visualize shear layer and vortex activity. A low-order model of dynamic stall was developed using dynamic mode decomposition, from which primary and secondary dynamic separation modes were identified. The interaction between these two modes was able to capture the physics of dynamic stall and as such can be extended to other turbine configurations and problems in unsteady aerodynamics. Results from the linear pitch/surge frame are extrapolated to the rotating VAWT frame to investigate the behavior of identified flow structures.

  19. Numerical Solution of Inviscid Compressible Steady Flows around the RAE 2822 Airfoil

    Science.gov (United States)

    Kryštůfek, P.; Kozel, K.

    2015-05-01

    The article presents results of a numerical solution of subsonic, transonic and supersonic flows described by the system of Euler equations in 2D compressible flows around the RAE 2822 airfoil. Authors used FVM multistage Runge-Kutta method to numerically solve the flows around the RAE 2822 airfoil. The results are compared with the solution using the software Ansys Fluent 15.0.7.

  20. Airfoil design using a coupled euler and integral boundary layer method with adjoint based sensitivities

    Science.gov (United States)

    Edwards, S.; Reuther, J.; Chattot, J. J.

    The objective of this paper is to present a control theory approach for the design of airfoils in the presence of viscous compressible flows. A coupled system of the integral boundary layer and the Euler equations is solved to provide rapid flow simulations. An adjoint approach consistent with the complete coupled state equations is employed to obtain the sensitivities needed to drive a numerical optimization algorithm. Design to a target pressure distribution is demonstrated on an RAE 2822 airfoil at transonic speeds.

  1. Predicting extreme loads effects on wind turbines considering uncertainty in airfoil data

    OpenAIRE

    Abdallah, Imad; Natarajan, Anand; Sørensen, John Dalsgaard

    2013-01-01

    The sources contributing to uncertainty in a wind turbine blade static airfoil data include wind tunnel testing, CFD calculations, 3D rotational corrections based on CFD or empirical models, surface roughness corrections, Reynolds number corrections, expansion to the full 360-degree angle of attack range, validation by full scale measurements, and geometric distortions of the blade during manufacturing and under loading. In this paper a stochastic model of the static airfoil data is proposed ...

  2. Parametric analyses for synthetic jet control on separation and stall over rotor airfoil

    OpenAIRE

    Zhao Guoqing; Zhao Qijun

    2014-01-01

    Numerical simulations are performed to investigate the effects of synthetic jet control on separation and stall over rotor airfoils. The preconditioned and unsteady Reynolds-averaged Navier–Stokes equations coupled with a k − ω shear stream transport turbulence model are employed to accomplish the flowfield simulation of rotor airfoils under jet control. Additionally, a velocity boundary condition modeled by a sinusoidal function is developed to fulfill the perturbation effect of periodic jet...

  3. Flow past a self-oscillating airfoil with two degrees of freedom: measurements and simulations

    OpenAIRE

    Šidlof Petr; Štěpán Martin; Vlček Václav; Řidký Václav; Šimurda David; Horáček Jaromír

    2014-01-01

    The paper focuses on investigation of the unsteady subsonic airflow past an elastically supported airfoil for subcritical flow velocities and during the onset of the flutter instability. A physical model of the NACA0015 airfoil has been designed and manufactured, allowing motion with two degrees of freedom: pitching (rotation about the elastic axis) and plunging (vertical motion). The structural mass and stiffness matrix can be tuned to certain extent, so that the natural frequencies of the t...

  4. TOPFARM, HawtOpt, AirfoilOpt: Three FUSED-Wind based toolsets

    OpenAIRE

    Pierre-Elouan Réthoré; Frederik Zahle

    2015-01-01

    A presentation about 3 FUSED-Wind based tools developed at DTU Wind Energy. TOPFARM is a tool to optimize wind farm layout from the wind farm owner perspective. HawtOpt is a tool to perform a coupled aero-elastic-structural optimization of wind turbine rotors. AirfoilOpt is a tool to perform coupled aero-structrual optimization of wind turbine blade airfoils.

  5. A study of long separation bubble on thick airfoils and its consequent effects

    International Nuclear Information System (INIS)

    Highlights: • Effects of long separation bubbles on airfoil performance have been discussed. • The bubble is found to induce a camber-effect on the airfoil. • Effects of Re, TI and angle of attack on the bubble have been presented. • Appropriate modelling methodology of the separation-induced transition is presented. • Comparison of γ–Reθ and κ–κL–ω model for separation bubble in 2D is presented. - Abstract: A parametric study has been performed to analyse the flow around the thick-symmetric NACA 0021 airfoil in order to better understand the characteristics and effects of long separation bubbles (LoSBs) that exist on such airfoils at low Reynolds numbers and turbulence intensities. In the article, the prediction capabilities of two recently-developed transition models, the correlation-based γ–Reθ model and the laminar-kinetic-energy-based κ–κL–ω model are assessed. Two-dimensional steady-state simulations indicated that the κ–κL–ω model predicted the separation and reattachment process accurately when compared with published experimental work. The model was then used to study the attributes and the effects of LoSBs as a function of the angle of attack, freestream turbulence intensity and Reynolds number. It was observed that LoSBs considerably degrade the aerodynamic performance of airfoils and lead to abrupt stall behaviour. It is, furthermore, illustrated that the presence of the LoSB leads to an induced camber effect on the airfoil that increases as the airfoil angle of attack increases due to the upstream migration of the bubble. An increase in the Reynolds number or turbulence levels leads to a reduction in the bubble extent, considerably improving the airfoil performance and leading to a progressive trailing-edge stall

  6. A Numerical Study of Aerodynamic Performance and Noise of a Bionic Airfoil Based on Owl Wing

    OpenAIRE

    Xiaomin Liu; Xiang Liu

    2014-01-01

    Noise reduction and efficiency enhancement are the two important directions in the development of the multiblade centrifugal fan. In this study, we attempt to develop a bionic airfoil based on the owl wing and investigate its aerodynamic performance and noise-reduction mechanism at the relatively low Reynolds number. Firstly, according to the geometric characteristics of the owl wing, a bionic airfoil is constructed as the object of study at Reynolds number of 12,300. Secondly, the large eddy...

  7. The design of post-buckled spinal structures for airfoil shape control using optimization methods

    OpenAIRE

    Ursache, N.M.; Bressloff, N.W.; Keane, A.J.

    2004-01-01

    In this paper we examine the use of optimization methods and a variety of shape definition schemes to design spinal structures for the control of deformable shape airfoils. The aim is to find structures that, when suitably loaded, can be used to alter the aerodynamic performance of a cladding that forms the airfoil. Further, by using structures that are acting in the post buckling regime it is possible to obtain significant changes in shape with only modest changes in applied load.

  8. Surface pressure and aerodynamic loads determination of a transonic airfoil based on particle image velocimetry

    OpenAIRE

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

    2009-01-01

    The present investigation assesses a procedure to extract the aerodynamic loads and pressure distribution on an airfoil in the transonic flow regime from particle image velocimetry (PIV) measurements. The wind tunnel model is a two-dimensional NACA-0012 airfoil, and the PIV velocity data are used to evaluate pressure fields, whereas lift and drag coefficients are inferred from the evaluation of momentum contour and wake integrals. The PIV-based results are compared to those derived from conve...

  9. An airloads theory for morphing airfoils in dynamic stall with experimental correlation

    Science.gov (United States)

    Ahaus, Loren A.

    Helicopter rotor blades frequently encounter dynamic stall during normal flight conditions, limiting the applicability of classical thin-airfoil theory at large angles of attack. Also, it is evident that because of the largely different conditions on the advancing and retreating sides of the rotor, future rotorcraft may incorporate dynamically morphing airfoils (trailing-edge aps, dynamic camber, dynamic droop, etc.). Reduced-order aerodynamic models are needed for preliminary design and ight simulation. A unified model for predicting the airloads on a morphing airfoil in dynamic stall is presented, consisting of three components. First, a linear airloads theory allows for arbitrary airfoil deformations consistent with a morphing airfoil. Second, to capture the effects of the wake, the airloads theory is coupled to an induced ow model. Third, the overshoot and time delay associated with dynamic stall are modeled by a second-order dynamic filter, along the lines of the ONERA dynamic stall model. This paper presents a unified airloads model that allows arbitrary airfoil morphing with dynamic stall. Correlations with experimental data validate the theory.

  10. Drag Coefficient of Water Droplets Approaching the Leading Edge of an Airfoil

    Science.gov (United States)

    Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida Garcia

    2013-01-01

    This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. An airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Results are presented and discussed for drag coefficients of droplets with diameters in the range of 300 to 1800 micrometers, and airfoil velocities of 50, 70 and 90 meters/second. The effect of droplet oscillation on the drag coefficient is discussed.

  11. Numerical Simulation of Airfoil Aerodynamic Penalties and Mechanisms in Heavy Rain

    Directory of Open Access Journals (Sweden)

    Zhenlong Wu

    2013-01-01

    Full Text Available Numerical simulations that are conducted on a transport-type airfoil, NACA 64-210, at a Reynolds number of 2.6×106 and LWC of 25 g/m3 explore the aerodynamic penalties and mechanisms that affect airfoil performance in heavy rain conditions. Our simulation results agree well with the experimental data and show significant aerodynamic penalties for the airfoil in heavy rain. The maximum percentage decrease in CL is reached by 13.2% and the maximum percentage increase in CD by 47.6%. Performance degradation in heavy rain at low angles of attack is emulated by an originally creative boundary-layer-tripped technique near the leading edge. Numerical flow visualization technique is used to show premature boundary-layer separation at high angles of attack and the particulate trajectories at various angles of attack. A mathematic model is established to qualitatively study the water film effect on the airfoil geometric changes. All above efforts indicate that two primary mechanisms are accountable for the airfoil aerodynamic penalties. One is to cause premature boundary-layer transition at low AOA and separation at high AOA. The other occurs at times scales consistent with the water film layer, which is thought to alter the airfoil geometry and increase the mass effectively.

  12. Mechanism of Water Droplet Breakup Near the Leading Edge of an Airfoil

    Science.gov (United States)

    Vargas, Mario; Sor, Suthyvann; Magarino, Adelaida, Garcia

    2012-01-01

    This work presents results of an experimental study on droplet deformation and breakup near the leading edge of an airfoil. The experiment was conducted in the rotating rig test cell at the Instituto Nacional de Tecnica Aeroespacial (INTA) in Madrid, Spain. The airfoil model was placed at the end of the rotating arm and a monosize droplet generator produced droplets that fell from above, perpendicular to the path of the airfoil. The interaction between the droplets and the airfoil was captured with high speed imaging and allowed observation of droplet deformation and breakup as the droplet approached the airfoil near the stagnation line. Image processing software was used to measure the position of the droplet centroid, equivalent diameter, perimeter, area, and the major and minor axes of an ellipse superimposed over the deforming droplet. The horizontal and vertical displacement of each droplet against time was also measured, and the velocity, acceleration, Weber number, Bond number, Reynolds number, and the drag coefficients were calculated along the path of the droplet to the beginning of breakup. Droplet deformation is defined and studied against main parameters. The high speed imaging allowed observation of the actual mechanism of breakup and identification of the sequence of configurations from the initiation of the breakup to the disintegration of the droplet. Results and comparisons are presented for droplets of diameters in the range of 500 to 1800 microns, and airfoil velocities of 70 and 90 m/sec.

  13. Effects of kinematics on aerodynamic periodicity for a periodically plunging airfoil

    Science.gov (United States)

    Wu, Jianghao; Wang, Dou; Zhang, Yanlai

    2015-12-01

    In conventional Micro-Air-Vehicle design inspired by insects, the periodical motion of flapping airfoil usually leads to generation of a periodical aerodynamic force. However, recent studies indicate that time courses of aerodynamic force and flow structure of a flapping airfoil may be non-periodical even though the airfoil undergoes a periodical motion. In this paper, a computational fluid dynamics analysis is employed to investigate the effects of some dimensionless variables, such as Reynolds number, plunging amplitude, advance ratio, and angle of attack, on the periodicity of the flow around a flapping airfoil. The governing equations in an inertial frame of reference are solved to obtain unsteady flow structure and aerodynamic behaviors of the airfoil. It is found in the results that the periodicity of the flow and aerodynamics is greatly dependent on Reynolds number and plunging amplitude. Under given conditions, the product of these two variables may be utilized as a criterion parameter to judge whether the time course of the flow is periodical or not. In addition, a new mechanism that accounts for the non-periodical flow is revealed to explain the flow of airfoil with pre-stall angle of attack.

  14. Numerical Simulations of Subscale Wind Turbine Rotor Inboard Airfoils at Low Reynolds Number

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, Myra L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Thermal/ Fluid Sciences & Engineering Dept.; Maniaci, David Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Wind Energy Technologies Dept.; Resor, Brian R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Wind Energy Technologies Dept.

    2015-04-01

    New blade designs are planned to support future research campaigns at the SWiFT facility in Lubbock, Texas. The sub-scale blades will reproduce specific aerodynamic characteristics of utility-scale rotors. Reynolds numbers for megawatt-, utility-scale rotors are generally above 2-8 million. The thickness of inboard airfoils for these large rotors are typically as high as 35-40%. The thickness and the proximity to three-dimensional flow of these airfoils present design and analysis challenges, even at the full scale. However, more than a decade of experience with the airfoils in numerical simulation, in the wind tunnel, and in the field has generated confidence in their performance. Reynolds number regimes for the sub-scale rotor are significantly lower for the inboard blade, ranging from 0.7 to 1 million. Performance of the thick airfoils in this regime is uncertain because of the lack of wind tunnel data and the inherent challenge associated with numerical simulations. This report documents efforts to determine the most capable analysis tools to support these simulations in an effort to improve understanding of the aerodynamic properties of thick airfoils in this Reynolds number regime. Numerical results from various codes of four airfoils are verified against previously published wind tunnel results where data at those Reynolds numbers are available. Results are then computed for other Reynolds numbers of interest.

  15. Design of a family of new advanced airfoils for low wind class turbines

    International Nuclear Information System (INIS)

    In order to maximize the ratio of energy capture and reduce the cost of energy, the selection of the airfoils to be used along the blade plays a crucial role. Despite the general usage of existing airfoils, more and more, families of airfoils specially tailored for specific applications are developed. The present research is focused on the design of a new family of airfoils to be used for the blade of one megawatt wind turbine working in low wind conditions. A hybrid optimization scheme has been implemented, combining together genetic and gradient based algorithms. Large part of the work is dedicated to present and discuss the requirements that needed to be satisfied in order to have a consistent family of geometries with high efficiency, high lift and good structural characteristics. For each airfoil, these characteristics are presented and compared to the ones of existing airfoils. Finally, the aerodynamic design of a new blade for low wind class turbine is illustrated and compared to a reference shape developed by using existing geometries. Due to higher lift performance, the results show a sensitive saving in chords, wetted area and so in loads in idling position

  16. Simultaneous Investigation of Flexibility and Plasma Actuation Effects on the Aerodynamic Characteristics of an Oscillating Airfoil

    Directory of Open Access Journals (Sweden)

    Arash Mahboubi Doust

    2016-01-01

    Full Text Available In this work, a numerical study of two dimensional laminar incompressible flow around the flexible oscillating NACA0012 airfoil is performed using the open source code OpenFOAM. Oscillatory motion types including pitching and flapping is considered. Reynolds number for these motions is assumed fixed at 12000. One of the important issues that must be considered in designing air structures, in particular the aircraft wing, is the interaction between the air and the elastic aircraft wings that is known as the Aeroelastic phenomenon. For this purpose, the effect of airfoil flexibility and flow induced vibration in these motion types is investigated and compared with the case of rigid airfoil. It is observed that the flexibility in both types of motions causes improvement of the thrust which is boosted with increasing the frequency. Contrary to thrust, the significant improvement of lift is only achievable in high frequencies. It was also found that the effect of flexibility on the flapping motion is higher than the pitching motion. For flow control on the airfoil, Dielectric Barrier Discharge plasma actuator is used in the trailing edge of a flexible airfoil, and its effect on the flexible airfoil is also investigated.

  17. Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

    Directory of Open Access Journals (Sweden)

    Phillip M. Ligrani

    2006-10-01

    Full Text Available The wake turbulence structure of a cambered airfoil is studied experimentally, including the effects of surface roughness, at different freestream turbulence levels in a transonic flow. As the level of surface roughness increases, all wake profile quantities broaden significantly and nondimensional vortex shedding frequencies decrease. Freestream turbulence has little effect on the wake velocity profiles, turbulence structure, and vortex shedding frequency, especially downstream of airfoils with rough surfaces. Compared with data from a symmetric airfoil, wake profiles produced by the cambered airfoils also have significant dependence on surface roughness, but are less sensitive to variations of freestream turbulence intensity. The cambered airfoil also produces larger streamwise velocity deficits, and broader wakes compared to the symmetric airfoil.

  18. Numerical exploration of the origin of aerodynamic enhancements in [low-Reynolds number] corrugated airfoils

    Science.gov (United States)

    Barnes, Caleb J.; Visbal, Miguel R.

    2013-11-01

    This paper explores the flow structure of a corrugated airfoil using a high-fidelity implicit large eddy simulation approach. The first three-dimensional simulations for a corrugated wing section are presented considering a range of Reynolds numbers of Rec = 5 × 103 to 5.8 × 104 bridging the gap left by previous numerical and experimental studies. Several important effects are shown to result from the corrugations in the leading-edge region. First, interaction between the detached shear layer and the first corrugation peak promotes recirculation upstream and enhances transition to turbulence due to flow instabilities. Thus, early transitional flow develops on the corrugated wing which helps to delay stall even at Reynolds numbers as low as Rec = 1 × 104. Transition is shown to occur as early as Rec = 7.5 × 103 and quickly advances toward the leading-edge as Reynolds number is increased. Modification of the first corrugation peak height produces significantly reduced separation and improved aerodynamic forces demonstrating the sensitivity of flow behavior to leading-edge geometry. Second, the unusual orientation of the corrugated surface and strong suction resulting from rapidly turning fluid over the separated region upstream of the first corrugation produces a new effect which serves to reduce drag. This effect was amplified through the enhanced interaction produced by a modified geometry. Corrugations were found to be most advantageous in the leading-edge region and could be optimized to properly take advantage of the flow field under different operating conditions.

  19. RETRIEVAL EQUIPMENT DESCRIPTIONS

    International Nuclear Information System (INIS)

    The objective and the scope of this document are to list and briefly describe the major mobile equipment necessary for waste package (WP) retrieval from the proposed subsurface nuclear waste repository at Yucca Mountain. Primary performance characteristics and some specialized design features of the equipment are explained and summarized in the individual subsections of this document. There are no quality assurance requirements or QA controls in this document. Retrieval under normal conditions is accomplished with the same fleet of equipment as is used for emplacement. Descriptions of equipment used for retrieval under normal conditions is found in Emplacement Equipment Descriptions, DI: BCAF00000-01717-5705-00002 (a document in progress). Equipment used for retrieval under abnormal conditions is addressed in this document and consists of the following: (1) Inclined Plane Hauler; (2) Bottom Lift Transporter; (3) Load Haul Dump (LHD) Loader; (4) Heavy Duty Forklift for Emplacement Drifts; (5) Covered Shuttle Car; (6) Multipurpose Vehicle; and (7) Scaler

  20. Full-scale semispan tests of a business-jet wing with a natural laminar flow airfoil

    Science.gov (United States)

    Hahne, David E.; Jordan, Frank L., Jr.

    1991-01-01

    A full-scale semispan model was investigated to evaluate and document the low-speed, high-lift characteristics of a business-jet class wing that utilized the HSNLF(1)-0213 airfoil section and a single-slotted flap system. Also, boundary-layer transition effects were examined, a segmented leading-edge droop for improved stall/spin resistance was studied, and two roll-controlled devices were evaluated. The wind-tunnel investigation showed that deployment of single-slotted, trailing-edge flap was effective in providing substantial increments in lift required for takeoff and landing performance. Fixed-transition studies to investigate premature tripping of the boundary layer indicated no adverse effects in lift and pitching-moment characteristics for either the cruise or landing configuration. The full-scale results also suggested the need to further optimize the leading-edge droop design that was developed in the subscale tests.