The Experts below are selected from a list of 2256 Experts worldwide ranked by ideXlab platform

Paruchuri Chaitanya - One of the best experts on this subject based on the ideXlab platform.

  • analytical and experimental investigation into the effects of Leading Edge Radius on gust aerofoil interaction noise
    Journal of Fluid Mechanics, 2017
    Co-Authors: Lorna J Ayton, Paruchuri Chaitanya
    Abstract:

    This paper investigates the effects of local Leading-Edge geometry on unsteady aerofoil interaction noise. Analytical results are obtained by extending previous work for parabolic Leading Edges to Leading Edges of the form xm for 0 < m < 1. Rapid distortion theory governs the interaction of an unsteady vortical perturbation with a rigid aerofoil in compressible steady mean flow that is uniform far upstream. For high-frequency gusts interacting with aerofoils of small total thickness this allows a matched asymptotic solution to be obtained. This paper mainly focusses on obtaining the analytic solution in the Leading-Edge inner region, which is the dominant term in determining the total far-field acoustic directivity, and contains the effects of the local Leading-Edge geometry. Experimental measurements for the noise generated by aerofoils with different Leading-Edge nose radii in uniform flow with approximate homogeneous, isotropic turbulence are also presented. Both experimental and analytic results predict that a larger nose Radius generates less overall noise in low-Mach-number flow. By considering individual terms in the analytic solution, this paper is able to propose reasons behind this result.

Van Bussel G.j.w. - One of the best experts on this subject based on the ideXlab platform.

  • High-Lift Low Reynolds Number Aerofoils With Specified Pressure Drop for Ducted Wind Turbine
    2017
    Co-Authors: Tang J., Van Bussel G.j.w.
    Abstract:

    A new high-lift aerofoil modification for the duct has been developed and will be experimentally tested in a small wind tunnel. Aerofoils for such wind tunnel ducts typically operate in the low Reynolds number range from 2 × 105 to 6 × 105. The effect of a duct and of rotor on power and pressure drop were considered separately in previous studies. This paper focuses on the optimization of aerofoil geometry for a Reynolds number of 3 × 105 taking into account of the presence of a screen, having a pressure drop similar to a real rotor. In particular, the current work concentrates on obtaining high lift, instead of high lift-to-drag ratio. Since high lift is the only desirable feature when modifying an aerofoil for ducts, the factors most related to enhanced high-lift low Reynolds numbers aerofoil performance are investigated. Previous experimental data of a three-dimension aerofoil-shaped duct model are used. Combining these data, and applying the Liebeck type high-lift design philosophy, which is to make use of an optimal pressure recovery with aft loading, variations in thickness, camber, and the shape of Leading and trailing Edges are analysed through the fully inversed method. The XFOIL 6.99 code was adopted as the analyse tool in this study. With the specified velocity distribution, it is found that an increase of both camber and thickness of the duct leads to an increase in lift coefficient with the presence of the pressure drop. In particular, the thickness increment for the aft part of the aerofoil generates higher lift coefficient. The installation of screen divides the duct into two parts, the duct fore part starts from the Leading Edge until the screen plane, while the duct aft part includes the screen plane to trailing Edge. It is observed from previous experimental data that, with the screen presence, the front stagnation point moves towards the inner part of the duct. Consequently, the pressure coefficient reduces in the front part of the suction side, although the pressure differences, between the upper surface and the lower surface, of the duct fore part enlarges. Decreasing the Leading Edge Radius, in essence, accelerates the airflow around it so that a negative area was created. Building on these results, the modified aerofoil model is fabricated and will be tested in a wind tunnel experiment. The test two-dimension model, with the assumption of symmetrical flow, is composed of an aerofoil and a uniform porous screen to simulate half part of the rotor from centreline. The aerofoil has a chord length of 20 mm and the screen has a length of 130 mm in vertical direction. To find the highest lift coefficient of this 2-dimension model, measurements will be conducted with the varying angle of attack and wind speed. Moreover, to investigate the effect of screen loading onto the configuration, there will be two different screens tested. Since the experiment will be carried out in April 2017 the comparison with the XFOIL 6.99 predictions cannot be provided at present, but will be shown during the symposium

  • High-Lift Low Reynolds Number Aerofoils With Specified Pressure Drop for Ducted Wind Turbine
    2017
    Co-Authors: Tang J., Van Bussel G.j.w.
    Abstract:

    A new high-lift aerofoil modification for the duct has been developed and will be experimentally tested in a small wind tunnel. Aerofoils for such wind tunnel ducts typically operate in the low Reynolds number range from 2 × 105 to 6 × 105. The effect of a duct and of rotor on power and pressure drop were considered separately in previous studies. This paper focuses on the optimization of aerofoil geometry for a Reynolds number of 3 × 105 taking into account of the presence of a screen, having a pressure drop similar to a real rotor. In particular, the current work concentrates on obtaining high lift, instead of high lift-to-drag ratio. Since high lift is the only desirable feature when modifying an aerofoil for ducts, the factors most related to enhanced high-lift low Reynolds numbers aerofoil performance are investigated. Previous experimental data of a three-dimension aerofoil-shaped duct model are used. Combining these data, and applying the Liebeck type high-lift design philosophy, which is to make use of an optimal pressure recovery with aft loading, variations in thickness, camber, and the shape of Leading and trailing Edges are analysed through the fully inversed method. The XFOIL 6.99 code was adopted as the analyse tool in this study. With the specified velocity distribution, it is found that an increase of both camber and thickness of the duct leads to an increase in lift coefficient with the presence of the pressure drop. In particular, the thickness increment for the aft part of the aerofoil generates higher lift coefficient. The installation of screen divides the duct into two parts, the duct fore part starts from the Leading Edge until the screen plane, while the duct aft part includes the screen plane to trailing Edge. It is observed from previous experimental data that, with the screen presence, the front stagnation point moves towards the inner part of the duct. Consequently, the pressure coefficient reduces in the front part of the suction side, although the pressure differences, between the upper surface and the lower surface, of the duct fore part enlarges. Decreasing the Leading Edge Radius, in essence, accelerates the airflow around it so that a negative area was created. Building on these results, the modified aerofoil model is fabricated and will be tested in a wind tunnel experiment. The test two-dimension model, with the assumption of symmetrical flow, is composed of an aerofoil and a uniform porous screen to simulate half part of the rotor from centreline. The aerofoil has a chord length of 20 mm and the screen has a length of 130 mm in vertical direction. To find the highest lift coefficient of this 2-dimension model, measurements will be conducted with the varying angle of attack and wind speed. Moreover, to investigate the effect of screen loading onto the configuration, there will be two different screens tested. Since the experiment will be carried out in April 2017 the comparison with the XFOIL 6.99 predictions cannot be provided at present, but will be shown during the symposium.Wind Energ

Lorna J Ayton - One of the best experts on this subject based on the ideXlab platform.

  • analytical and experimental investigation into the effects of Leading Edge Radius on gust aerofoil interaction noise
    Journal of Fluid Mechanics, 2017
    Co-Authors: Lorna J Ayton, Paruchuri Chaitanya
    Abstract:

    This paper investigates the effects of local Leading-Edge geometry on unsteady aerofoil interaction noise. Analytical results are obtained by extending previous work for parabolic Leading Edges to Leading Edges of the form xm for 0 < m < 1. Rapid distortion theory governs the interaction of an unsteady vortical perturbation with a rigid aerofoil in compressible steady mean flow that is uniform far upstream. For high-frequency gusts interacting with aerofoils of small total thickness this allows a matched asymptotic solution to be obtained. This paper mainly focusses on obtaining the analytic solution in the Leading-Edge inner region, which is the dominant term in determining the total far-field acoustic directivity, and contains the effects of the local Leading-Edge geometry. Experimental measurements for the noise generated by aerofoils with different Leading-Edge nose radii in uniform flow with approximate homogeneous, isotropic turbulence are also presented. Both experimental and analytic results predict that a larger nose Radius generates less overall noise in low-Mach-number flow. By considering individual terms in the analytic solution, this paper is able to propose reasons behind this result.

Abdul Latif Ainullotfi - One of the best experts on this subject based on the ideXlab platform.

  • Experimental investigation on blunt-Edged UTM delta wing VFE-2 configurations at low reynolds number
    'Praise Worthy Prize', 2018
    Co-Authors: Daman Huri, Muhammad Zal Aminullah, Said Mazuriah, Mat Shabudin, Mansor Shuhaimi, Dahalan, Md. Nizam, Abdul Latif Ainullotfi
    Abstract:

    The flow behaviour over the upper surface of a blunt-Edged delta wing is mainly governed by a complicated Leading Edge vortex. This paper presents an experimental investigation on blunt-Edged UTM VFE-2 delta wing model at low Reynolds numbers. The primary vortex for sharp-Edged delta wing develops in the apex region even at low angles of attack. However, this situation does not happen for blunt-Edged wings; the primary vortex in the Leading Edge region develops at a certain chordwise position on the wing. The primary vortex progresses upstream or downstream depending on the Leading Edge profile, the angle of attack and Reynolds number. A decrease in Reynolds number will accelerate the upstream progression of the primary vortex towards the wing apex. In the VFE-2 research group, many experiments were conducted at Reynolds number of 1×106 and above. Thus, the main objective of this study was to investigate the upstream progression of Leading Edge primary vortex on a blunt-Edged delta wing at Reynolds numbers of 0.5×106, 0.75×106 and 1.0×106. Wind tunnel experiments were performed at three different flow velocities, 8.7 m/s, 13.1 m/s and 17.5 m/s corresponding to Reynolds numbers of 0.5×106, 0.75×106 and 1.0×106. Two measurement techniques were employed on the upper surface of the wing, i.e. experimental surface pressure and tuft techniques. Experiments were also conducted on two different Leading Edge profiles namely medium and large Radius profiles with different Leading Edge Radius-to-wing chord ratio. Pressure coefficients on the upper surface of the wing were plotted to observe the characteristic primary vortex, the upstream progression of the primary vortex and also the characteristics of vortex breakdown. The results obtained indicate that the primary vortex rapidly formed when the Reynolds number was decreased. Analysis in the apex region showed that the attached flow still existed even at a very low Reynolds number of 0.5 × 106

  • Reynolds number effects on flow topology above blunt-Edge delta wing VFE-2 configurations
    2015
    Co-Authors: Said Mazuriah, Mat Shabudin, Mansor Shuhaimi, Abdul Latif Ainullotfi, Mat Lazim Tholudin
    Abstract:

    This paper discusses further the effects of Reynolds number, angle of attack and Leading Edge bluntness on the flow topology above delta wing VFE-2 configurations. In this project two delta wing models differentiated by its Leading Edge Radius to the mean aerodynamics chord ratio of 0.15 and 0.3, namely the medium and large Radius wing, were tested in Universiti Teknologi Malaysia wind tunnel. The relationship between the Leading Edge primary vortex and the occurrence of a secondary vortex called the inner vortex on the round-Edged delta wings are discussed. The effects of Leading Edge bluntness, angle of attack and Reynolds number on both vortex systems are further discussed in this paper. The tests in this study were performed at speeds of 18.0 m/s, 36.1 m/s, and 54.2 m/s representing Reynolds numbers of 1×106, 2×106 and 3×106 and based on the mean aerodynamic chord. Two measurement techniques were employed on the models i.e. steady force balance and surface pressure data. The current experiments showed that an increase in Leading Edge bluntness and Reynolds number can delay the formation of the primary vortex towards the aft portions of the wing

Tang J. - One of the best experts on this subject based on the ideXlab platform.

  • High-Lift Low Reynolds Number Aerofoils With Specified Pressure Drop for Ducted Wind Turbine
    2017
    Co-Authors: Tang J., Van Bussel G.j.w.
    Abstract:

    A new high-lift aerofoil modification for the duct has been developed and will be experimentally tested in a small wind tunnel. Aerofoils for such wind tunnel ducts typically operate in the low Reynolds number range from 2 × 105 to 6 × 105. The effect of a duct and of rotor on power and pressure drop were considered separately in previous studies. This paper focuses on the optimization of aerofoil geometry for a Reynolds number of 3 × 105 taking into account of the presence of a screen, having a pressure drop similar to a real rotor. In particular, the current work concentrates on obtaining high lift, instead of high lift-to-drag ratio. Since high lift is the only desirable feature when modifying an aerofoil for ducts, the factors most related to enhanced high-lift low Reynolds numbers aerofoil performance are investigated. Previous experimental data of a three-dimension aerofoil-shaped duct model are used. Combining these data, and applying the Liebeck type high-lift design philosophy, which is to make use of an optimal pressure recovery with aft loading, variations in thickness, camber, and the shape of Leading and trailing Edges are analysed through the fully inversed method. The XFOIL 6.99 code was adopted as the analyse tool in this study. With the specified velocity distribution, it is found that an increase of both camber and thickness of the duct leads to an increase in lift coefficient with the presence of the pressure drop. In particular, the thickness increment for the aft part of the aerofoil generates higher lift coefficient. The installation of screen divides the duct into two parts, the duct fore part starts from the Leading Edge until the screen plane, while the duct aft part includes the screen plane to trailing Edge. It is observed from previous experimental data that, with the screen presence, the front stagnation point moves towards the inner part of the duct. Consequently, the pressure coefficient reduces in the front part of the suction side, although the pressure differences, between the upper surface and the lower surface, of the duct fore part enlarges. Decreasing the Leading Edge Radius, in essence, accelerates the airflow around it so that a negative area was created. Building on these results, the modified aerofoil model is fabricated and will be tested in a wind tunnel experiment. The test two-dimension model, with the assumption of symmetrical flow, is composed of an aerofoil and a uniform porous screen to simulate half part of the rotor from centreline. The aerofoil has a chord length of 20 mm and the screen has a length of 130 mm in vertical direction. To find the highest lift coefficient of this 2-dimension model, measurements will be conducted with the varying angle of attack and wind speed. Moreover, to investigate the effect of screen loading onto the configuration, there will be two different screens tested. Since the experiment will be carried out in April 2017 the comparison with the XFOIL 6.99 predictions cannot be provided at present, but will be shown during the symposium

  • High-Lift Low Reynolds Number Aerofoils With Specified Pressure Drop for Ducted Wind Turbine
    2017
    Co-Authors: Tang J., Van Bussel G.j.w.
    Abstract:

    A new high-lift aerofoil modification for the duct has been developed and will be experimentally tested in a small wind tunnel. Aerofoils for such wind tunnel ducts typically operate in the low Reynolds number range from 2 × 105 to 6 × 105. The effect of a duct and of rotor on power and pressure drop were considered separately in previous studies. This paper focuses on the optimization of aerofoil geometry for a Reynolds number of 3 × 105 taking into account of the presence of a screen, having a pressure drop similar to a real rotor. In particular, the current work concentrates on obtaining high lift, instead of high lift-to-drag ratio. Since high lift is the only desirable feature when modifying an aerofoil for ducts, the factors most related to enhanced high-lift low Reynolds numbers aerofoil performance are investigated. Previous experimental data of a three-dimension aerofoil-shaped duct model are used. Combining these data, and applying the Liebeck type high-lift design philosophy, which is to make use of an optimal pressure recovery with aft loading, variations in thickness, camber, and the shape of Leading and trailing Edges are analysed through the fully inversed method. The XFOIL 6.99 code was adopted as the analyse tool in this study. With the specified velocity distribution, it is found that an increase of both camber and thickness of the duct leads to an increase in lift coefficient with the presence of the pressure drop. In particular, the thickness increment for the aft part of the aerofoil generates higher lift coefficient. The installation of screen divides the duct into two parts, the duct fore part starts from the Leading Edge until the screen plane, while the duct aft part includes the screen plane to trailing Edge. It is observed from previous experimental data that, with the screen presence, the front stagnation point moves towards the inner part of the duct. Consequently, the pressure coefficient reduces in the front part of the suction side, although the pressure differences, between the upper surface and the lower surface, of the duct fore part enlarges. Decreasing the Leading Edge Radius, in essence, accelerates the airflow around it so that a negative area was created. Building on these results, the modified aerofoil model is fabricated and will be tested in a wind tunnel experiment. The test two-dimension model, with the assumption of symmetrical flow, is composed of an aerofoil and a uniform porous screen to simulate half part of the rotor from centreline. The aerofoil has a chord length of 20 mm and the screen has a length of 130 mm in vertical direction. To find the highest lift coefficient of this 2-dimension model, measurements will be conducted with the varying angle of attack and wind speed. Moreover, to investigate the effect of screen loading onto the configuration, there will be two different screens tested. Since the experiment will be carried out in April 2017 the comparison with the XFOIL 6.99 predictions cannot be provided at present, but will be shown during the symposium.Wind Energ