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Georgios Pechlivanoglou - One of the best experts on this subject based on the ideXlab platform.

  • Wake Analysis of a Finite Width Gurney Flap
    Journal of Engineering for Gas Turbines and Power, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap.The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.Copyright © 2015 by ASME

  • Wake Analysis of a Finite Width Gurney Flap
    Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap. The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.

  • wake vortex field of an airfoil equipped with an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Christian Oliver Paschereit
    Abstract:

    The aerodynamic loads on a two-dimensional airfoil can be altered with an active Gurney Flap placed at the trailing edge. The Flap can be moved either to the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with a finite as well as a full span active Gurney Flap were conducted in the wind tunnel. The dynamic wake during the Flaps movement was measured with a High Speed Mono PIV system at center-span location. Furthermore, the time-dependent stream-wise pressure distribution was measured with a wake rake at various spanwise positions. The time-dependent pressure measurements as well as the PIV snapshots were further analyzed with Fast Fourier Transformations as well as the Proper Orthogonal Decomposition technique. Results for the static non-moving Gurney Flap have shown, that the position of the vortex street is altered depending on the position of the Gurney Flap. The average flow-field showed the decamber mechanism which is responsible for altering the static loads. The frequency of the vortex street was found higher for the Flap deflected to the suction side than to the pressure side. The wake development during the active Flap deployment and retraction process was observed. Lift and drag development could be associated with a trigger to the wake development. It was found, that the change of lift was accompanied by a change of the vortex street in frequency as well as in vortex strength over the Flap movement.

  • experimental investigation of the aerodynamic lift response of an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Richard Berg, Christian Oliver Paschereit
    Abstract:

    The passive Gurney Flap has proven being a good mean to alter the static aerodynamic lift on an airfoil. The Gurney Flap can be applied to either the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with an active Gurney Flap were conducted in a wind tunnel to investigated the time dependent behavior of two-dimensional as well as finite Flaps. The time-dependent pressure response of the deploying Flaps were evaluated locally over the airfoils surface and the spanwise time-dependent lift was evaluated. Results have shown, that the lift response behaves differently for a Flap deployment than for a Flap retraction, where the convergence generally takes longer. Furthermore, the adjacent Flap sections of the finite Flap have shown to also experience a dynamic lift change. This response is different than the response in front of the Flap, which is due to the influence of to the surface pressure expansion around the finite Flap as well as the Flap tip vortices. The measurements have shown, that the timedependent lift in the adjacent sections do play a relevant part in the overall lift response of the wing.

Christian Oliver Paschereit - One of the best experts on this subject based on the ideXlab platform.

  • Wake Analysis of a Finite Width Gurney Flap
    Journal of Engineering for Gas Turbines and Power, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap.The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.Copyright © 2015 by ASME

  • Wake Analysis of a Finite Width Gurney Flap
    Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap. The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.

  • wake vortex field of an airfoil equipped with an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Christian Oliver Paschereit
    Abstract:

    The aerodynamic loads on a two-dimensional airfoil can be altered with an active Gurney Flap placed at the trailing edge. The Flap can be moved either to the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with a finite as well as a full span active Gurney Flap were conducted in the wind tunnel. The dynamic wake during the Flaps movement was measured with a High Speed Mono PIV system at center-span location. Furthermore, the time-dependent stream-wise pressure distribution was measured with a wake rake at various spanwise positions. The time-dependent pressure measurements as well as the PIV snapshots were further analyzed with Fast Fourier Transformations as well as the Proper Orthogonal Decomposition technique. Results for the static non-moving Gurney Flap have shown, that the position of the vortex street is altered depending on the position of the Gurney Flap. The average flow-field showed the decamber mechanism which is responsible for altering the static loads. The frequency of the vortex street was found higher for the Flap deflected to the suction side than to the pressure side. The wake development during the active Flap deployment and retraction process was observed. Lift and drag development could be associated with a trigger to the wake development. It was found, that the change of lift was accompanied by a change of the vortex street in frequency as well as in vortex strength over the Flap movement.

  • experimental investigation of the aerodynamic lift response of an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Richard Berg, Christian Oliver Paschereit
    Abstract:

    The passive Gurney Flap has proven being a good mean to alter the static aerodynamic lift on an airfoil. The Gurney Flap can be applied to either the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with an active Gurney Flap were conducted in a wind tunnel to investigated the time dependent behavior of two-dimensional as well as finite Flaps. The time-dependent pressure response of the deploying Flaps were evaluated locally over the airfoils surface and the spanwise time-dependent lift was evaluated. Results have shown, that the lift response behaves differently for a Flap deployment than for a Flap retraction, where the convergence generally takes longer. Furthermore, the adjacent Flap sections of the finite Flap have shown to also experience a dynamic lift change. This response is different than the response in front of the Flap, which is due to the influence of to the surface pressure expansion around the finite Flap as well as the Flap tip vortices. The measurements have shown, that the timedependent lift in the adjacent sections do play a relevant part in the overall lift response of the wing.

Alena B Bach - One of the best experts on this subject based on the ideXlab platform.

  • Wake Analysis of a Finite Width Gurney Flap
    Journal of Engineering for Gas Turbines and Power, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap.The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.Copyright © 2015 by ASME

  • Wake Analysis of a Finite Width Gurney Flap
    Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap. The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.

  • wake vortex field of an airfoil equipped with an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Christian Oliver Paschereit
    Abstract:

    The aerodynamic loads on a two-dimensional airfoil can be altered with an active Gurney Flap placed at the trailing edge. The Flap can be moved either to the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with a finite as well as a full span active Gurney Flap were conducted in the wind tunnel. The dynamic wake during the Flaps movement was measured with a High Speed Mono PIV system at center-span location. Furthermore, the time-dependent stream-wise pressure distribution was measured with a wake rake at various spanwise positions. The time-dependent pressure measurements as well as the PIV snapshots were further analyzed with Fast Fourier Transformations as well as the Proper Orthogonal Decomposition technique. Results for the static non-moving Gurney Flap have shown, that the position of the vortex street is altered depending on the position of the Gurney Flap. The average flow-field showed the decamber mechanism which is responsible for altering the static loads. The frequency of the vortex street was found higher for the Flap deflected to the suction side than to the pressure side. The wake development during the active Flap deployment and retraction process was observed. Lift and drag development could be associated with a trigger to the wake development. It was found, that the change of lift was accompanied by a change of the vortex street in frequency as well as in vortex strength over the Flap movement.

  • experimental investigation of the aerodynamic lift response of an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Richard Berg, Christian Oliver Paschereit
    Abstract:

    The passive Gurney Flap has proven being a good mean to alter the static aerodynamic lift on an airfoil. The Gurney Flap can be applied to either the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with an active Gurney Flap were conducted in a wind tunnel to investigated the time dependent behavior of two-dimensional as well as finite Flaps. The time-dependent pressure response of the deploying Flaps were evaluated locally over the airfoils surface and the spanwise time-dependent lift was evaluated. Results have shown, that the lift response behaves differently for a Flap deployment than for a Flap retraction, where the convergence generally takes longer. Furthermore, the adjacent Flap sections of the finite Flap have shown to also experience a dynamic lift change. This response is different than the response in front of the Flap, which is due to the influence of to the surface pressure expansion around the finite Flap as well as the Flap tip vortices. The measurements have shown, that the timedependent lift in the adjacent sections do play a relevant part in the overall lift response of the wing.

Christian Navid Nayeri - One of the best experts on this subject based on the ideXlab platform.

  • Wake Analysis of a Finite Width Gurney Flap
    Journal of Engineering for Gas Turbines and Power, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap.The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.Copyright © 2015 by ASME

  • Wake Analysis of a Finite Width Gurney Flap
    Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy, 2015
    Co-Authors: D. Holst, Alena B Bach, Christian Navid Nayeri, Christian Oliver Paschereit, Georgios Pechlivanoglou
    Abstract:

    The results of stereo Particle-Image-Velocimetry measurements are presented in this paper to gain further insight into the wake of a finite width Gurney Flap. It is attached to an FX 63-137 airfoil which is known for a very good performance at low Reynolds numbers and is therefore used for small wind turbines and is most appropriate for tests in the low speed wind tunnel presented in this study. The Gurney Flaps are a promising concept for load control on wind turbines but can have adverse side effects, e.g. shedding of additional vortices. The investigation focuses on frequencies and velocity distributions in the wake as well as on the structure of the induced tip vortices. Phase averaged velocity fields are derived of a Proper-Orthogonal-Decomposition based on the stereo PIV measurements. Additional hot-wire measurements were conducted to analyze the fluctuations downstream of the finite width Gurney Flaps. Experiments indicate a general tip vortex structure that is independent from Flap length but altered by the periodic shedding downstream of the Flap. The influence of Gurney Flaps on a small wind turbine is investigated by simulating a small 40 kW turbine in Q-Blade. They can serve as power control without the need of an active pitch system and the starting performance is additionally improved. The application of Gurney Flaps imply tonal frequencies in the wake of the blade. Simulation results are used to estimate the resulting frequencies. However, the solution of Gurney Flaps is a good candidate for large scale wind turbine implementation as well. A FAST simulation of the NREL 5MW turbine is used to generate realistic time series of the lift. The estimations of control capabilities predict a reduction in the standard deviation of the lift of up to 65%. Therefore finite width Gurney Flaps are promising to extend the lifetime of future wind turbines.

  • wake vortex field of an airfoil equipped with an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Christian Oliver Paschereit
    Abstract:

    The aerodynamic loads on a two-dimensional airfoil can be altered with an active Gurney Flap placed at the trailing edge. The Flap can be moved either to the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with a finite as well as a full span active Gurney Flap were conducted in the wind tunnel. The dynamic wake during the Flaps movement was measured with a High Speed Mono PIV system at center-span location. Furthermore, the time-dependent stream-wise pressure distribution was measured with a wake rake at various spanwise positions. The time-dependent pressure measurements as well as the PIV snapshots were further analyzed with Fast Fourier Transformations as well as the Proper Orthogonal Decomposition technique. Results for the static non-moving Gurney Flap have shown, that the position of the vortex street is altered depending on the position of the Gurney Flap. The average flow-field showed the decamber mechanism which is responsible for altering the static loads. The frequency of the vortex street was found higher for the Flap deflected to the suction side than to the pressure side. The wake development during the active Flap deployment and retraction process was observed. Lift and drag development could be associated with a trigger to the wake development. It was found, that the change of lift was accompanied by a change of the vortex street in frequency as well as in vortex strength over the Flap movement.

  • experimental investigation of the aerodynamic lift response of an active finite Gurney Flap
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Alena B Bach, Georgios Pechlivanoglou, Christian Navid Nayeri, Richard Berg, Christian Oliver Paschereit
    Abstract:

    The passive Gurney Flap has proven being a good mean to alter the static aerodynamic lift on an airfoil. The Gurney Flap can be applied to either the suction side for lift reduction or to the pressure side for lift enhancement. Measurements on a FX 63 -137 airfoil with an active Gurney Flap were conducted in a wind tunnel to investigated the time dependent behavior of two-dimensional as well as finite Flaps. The time-dependent pressure response of the deploying Flaps were evaluated locally over the airfoils surface and the spanwise time-dependent lift was evaluated. Results have shown, that the lift response behaves differently for a Flap deployment than for a Flap retraction, where the convergence generally takes longer. Furthermore, the adjacent Flap sections of the finite Flap have shown to also experience a dynamic lift change. This response is different than the response in front of the Flap, which is due to the influence of to the surface pressure expansion around the finite Flap as well as the Flap tip vortices. The measurements have shown, that the timedependent lift in the adjacent sections do play a relevant part in the overall lift response of the wing.

Jinjun Wang - One of the best experts on this subject based on the ideXlab platform.

  • Gurney-Flap Drag Penalty Reduction with a DBD Plasma Actuator
    Journal of Aerospace Engineering, 2017
    Co-Authors: Zhang Zeng, Jinjun Wang, Lihao Feng, Peiqing Liu
    Abstract:

    AbstractThe present research proposed a method to reduce the Gurney-Flap drag penalty with a dielectric barrier discharge (DBD) plasma actuator, which was mounted in front of the Gurney Flap to gen...

  • Numerical simulation of Gurney Flap on SFYT15thick airfoil
    Theoretical and Applied Mechanics Letters, 2016
    Co-Authors: Jinjun Wang, Muqing Yang, Chao Yan, Peiqing Liu
    Abstract:

    Abstract A two-dimensional steady Reynolds-averaged Navier–Stokes (RANS) equation was solved to investigate the effects of a Gurney Flap on SFYT15thick airfoil aerodynamic performance. This airfoil was designed for flight vehicle operating at 20 km altitude with freestream velocity of 25 m/s. The chord length ( C ) is 5 m and the Reynolds number based on chord length is R e = 7.76 × 10 5 . Gurney Flaps with the heights ranging from 0.25 % C to 3 % C were investigated. The shear stress transport (SST) k - ω turbulence model was used to simulate the flow structure around the airfoil. It is showed that Gurney Flap can enhance not only the prestall lift but also lift-to-drag ratio in a certain range of angles of attack. Specially, at cruise angle of attack ( α = 3 ° ), Gurney Flap with 0.5 % C height can increase lift-to-drag ratio by 2.7%, and lift coefficient by 12.9%, respectively. Furthermore, the surface pressure distribution, streamlines and trailing-edge flow structure around the airfoil are illustrated, which are helpful to understand the mechanisms of Gurney Flap on airfoil aerodynamic performance. Moreover, it is found that the increase of airfoil drag with Gurney Flap can be attributed to the increase of pressure drag between the windward and the leeward sides of Gurney Flap itself.

  • flow control over a naca 0012 airfoil using dielectric barrier discharge plasma actuator with a Gurney Flap
    Experiments in Fluids, 2012
    Co-Authors: Lihao Feng, Kwing-so Choi, Timothy Jukes, Jinjun Wang
    Abstract:

    Flow control study of a NACA 0012 airfoil with a Gurney Flap was carried out in a wind tunnel, where it was demonstrated that a dielectric-barrier-discharge (DBD) plasma actuator attached to the Flap could increase the lift further, but with a small drag penalty. Time-resolved PIV measurements of the near-wake region indicated that the plasma forcing shifted the wake downwards, reducing its recirculation length. Analysis of wake vortex dynamics suggested that the plasma actuator initially amplified the lower wake shear layer by adding momentum along the downstream surface of the Gurney Flap. This enhanced mutual entrainment between the upper and lower wake vortices, leading to an increase in lift on the airfoil.

  • Numerical Simulation of Gurney Flap on RAE-2822 Supercritical Airfoil
    Journal of Aircraft, 2011
    Co-Authors: Jinjun Wang, Peipei Zhang
    Abstract:

    A two-dimensional steady Reynolds-averaged Navier–Stokes equation was solved to investigate the effects of a Gurney Flap on RAE-2822 (Royal Aeronautical Establishment) supercritical airfoil aerodynamic performance. The heights ofGurneyFlaps range from0.25 to 3%airfoil chord lengths. The incompressible/compressibleNavier–Stokes equations were used to simulate the flow structure around the airfoils in subsonic/transonic flows, respectively, with the Spalart–Allmaras turbulence model. In comparison with the clean airfoil, the Gurney Flap can significantly increase the prestall lift and lift-to-drag ratio of an RAE-2822 airfoil at a small angle of attack. Nosedown pitching moment also increased with the Gurney Flap height. At both takeoff-and-landing status and cruise phase, the aerodynamic performance of the airfoil was significantly improved byGurney Flaps with the height below 1%airfoil chord length. In addition, the surface pressure distribution, wake flow velocity profile, and trailing-edge flow structure of the airfoil were illustrated, which helps to understand the mechanisms of the Gurney Flap to improve RAE-2822 airfoil aerodynamic performance.

  • dynamical mode decomposition of Gurney Flap wake flow
    Theoretical and Applied Mechanics Letters, 2011
    Co-Authors: Chong Pan, Jinjun Wang
    Abstract:

    The present work uses dynamic mode decomposition (DMD) to analyze wake flow of NACA0015 airfoil with Gurney Flap. The physics of DMD is first introduced. Then the PIV-measured wake flow velocity field is decomposed into dynamical modes. The vortex shedding pattern behind the trailing edge and its high-order harmonics have been captured with abundant information such as frequency, wavelength and convection speed. It is observed that high-order dynamic modes convect faster than low-order modes; moreover the wavelength of the dynamic modes scales with the corresponding frequency in power law.