The Experts below are selected from a list of 27429 Experts worldwide ranked by ideXlab platform
Jong-soo Choi - One of the best experts on this subject based on the ideXlab platform.
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noise reduction effect of airfoil and small scale rotor using serration trailing edge in a Wind Tunnel Test
Science China-technological Sciences, 2017Co-Authors: Jaeha Ryi, Jong-soo ChoiAbstract:This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the Wind Tunnel Test condition. In order to analyze the changes in the performance due to the inclusion of a serrated trailing edge designed to reduce noise, a 10 kW Wind turbine rotor was equipped with a thin serrated trailing edge. The restrictive condition for the serrated trailing edge equipped with the using of a 2D airfoil was examined through the using of a Wind Tunnel experiment after studying existing restrictive condition and analyzing prior research on serrated trailing edges. The aerodynamic performance and noise reduction effect of a small-scale model were investigated with the using of a serrated trailing edge. Moreover, the noise levels from the experiment were considered that the noise prediction method could be used for a full-scale rotor. It is confirmed that noise reduction effect is compared with Wind Tunnel Test data at the 2D airfoil and model rotor condition.
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Blockage effect correction for a scaled Wind turbine rotor by using Wind Tunnel Test data
Renewable Energy, 2015Co-Authors: Jaeha Ryi, Wook Rhee, Ui Chang Hwang, Jong-soo ChoiAbstract:Abstract This paper discusses the procedure of a blockage effect correction method involving small-scale Wind turbine rotor experimental data. To simulate the aerodynamic performance of full-scale rotors in the field, however, measured data from scaled model experiments need to be analyzed appropriately. One of the most important elements of such an analysis is a procedure to remove the blockage effect of the Wind Tunnel wall from the measured power data. In this paper, a correction algorithm proposed as part of Glauert's blockage effect correction method is used to process the data from a Wind turbine rotor Tested with three different Wind Tunnel sizes. Also, this study considered the modified blockage effect correction method, which has been used to process the rotor thrust data in closed-circuit Wind Tunnels and open-circuit Wind Tunnels. A small-scale rotor was Tested under the same operating conditions, i.e., the same advance ratio, rotating speed, rotor torque and speed of the Wind Tunnel. The small-scale Wind turbine rotor has a diameter of 1.408 m and a rotating speed according to the tip speed ratio. In each case, the effect of the blockage ratio and aerodynamic characteristics are determined using Wind Tunnel Test results and with a simple analytical correction method. The results of the modified correction method show that the aerodynamic performance levels during a Wind Tunnel Test are cleared by the blockage effect.
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a full scale prediction method for Wind turbine rotor noise by using Wind Tunnel Test data
AFORE, 2012Co-Authors: Jaeha Ryi, Jong-soo Choi, Seunghoon Lee, Soogab LeeAbstract:Abstract The development of a low-noise Wind turbine rotor and propeller is often cost-effective and is in fact a race against time to those who wish to build and Test a small-scale rotor instead of an expensive full-scale rotor. The issue of this approach has to do with the interpretation of Wind Tunnel model Test data in terms of both the frequency band and sound pressure level information for the noise scaling effect. This paper discusses a prediction method for the estimation of the noise generated from a full-scale Wind turbine rotor using Wind Tunnel Test data measured with both a small-scale rotor and a 2D section of the blade. The 2D airfoil self-noise and the scaled rotor noise were investigated with a series of Wind Tunnel experiments. Wind Tunnel data post-processing considered four aspects: removal of the Test condition effect, scaling to full scale, consideration of the Wind turbine rotor operating conditions, and the most important terms of full-scale rotor noise as adjustments to address the differences between the Wind Tunnel Test conditions and the full-scale operating conditions. A full-scale rotor noise prediction results comparison was performed by initially dividing the Test conditions into the condition of a 2D section noise Test and the condition of a small-scale rotor noise Test. Based on an airfoil section, the rotor was selected from a blade section at r / R = 0.75. The small-scale rotor was scaled down by a factor of 5.71 for the Wind Tunnel Test. Finally, the full-scale rotor noise data was compared with the Wind Tunnel Test data using a scaling estimation method.
Cheolwan Kim - One of the best experts on this subject based on the ideXlab platform.
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Design and Performance Evaluation of Propeller for Solar-Powered High-Altitude Long-Endurance Unmanned Aerial Vehicle
Hindawi Limited, 2018Co-Authors: Donghun Park, Taehwan Cho, Yunggyo Lee, Cheolwan KimAbstract:Design, Wind Tunnel Test, computational fluid dynamics (CFD) analysis, and flight Test data analysis are conducted for the propeller of EAV-3, which is a solar-powered high-altitude long-endurance unmanned aerial vehicle developed by Korea Aerospace Research Institute. The blade element momentum theory, in conjunction with minimum induced loss, is used as a basic design method. Airfoil data are obtained from CFD analysis, which takes into account the low Reynolds number effect. The response surface is evaluated for design variables by using design of experiment and kriging metamodel. The optimization is based on desirability function. A Wind Tunnel Test is conducted on the designed propeller. Numerical analyses are performed by using a commercial CFD code, and results are compared with those obtained from the design code and Wind Tunnel Test data. Flight Test data are analyzed based on several approximations and assumptions. The propeller performance is in good agreement with the numerical and measurement data in terms of tendency and behavior. The comparison of data confirms that the design method, Wind Tunnel Test, and CFD analysis used in this study are practically useful and valid for the development of a high-altitude propeller
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Wind Tunnel Test for the nrel phase vi rotor with 2 m diameter
Renewable Energy, 2014Co-Authors: Taehwan Cho, Cheolwan KimAbstract:Abstract The aerodynamic performance of the ‘NREL Phase VI’ rotor with a 2 m diameter was Tested in the open jet Test section. The original rotor with a 10.06 m diameter was Tested in the NASA Ames Tunnel and the Test result was used as validation data for the computational model. The Reynolds number of the sectional airfoils in the original Test is around 1.0E6 which is too high for a conventional Wind Tunnel with a diameter less than 5 m. The Wind Tunnel Test to study the Reynolds number effect on the rotor performance from Re = 0.1E6 to Re = 0.4E6 was conducted in the KARI low speed Wind Tunnel with a 5 m × 3.75 m open jet Test section. The torque generated by the blade was directly measured by the sensor installed in the rotating axis. The variation of the Reynolds number was achieved by changing the rotational speed. Two surface conditions, free transition and forced transition were employed in this Test to study the surface trip effect. The Test results for the free transition condition show that the power coefficient, Cp gradually increases with the Reynolds number, but the Cp for the forced transition condition does not vary with the Reynolds number. The maximum Cp for the free transition is 0.30 and it decrease to 0.22 for the forced transition conditions at the Reynolds number 0.4E6. The downstream flow velocity measured by 5-hole probe in the Wind Tunnel Test was compared with BEMT calculation result. The comparison results show that the torque dependency on Reynolds number in the blade is mainly originated from the airfoil drag characteristics. A model to estimate the power of full scale blade was suggested based on these measurement results. The estimated power shows a good agreement with the full scale Test result.
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aerodynamic analysis of tilt rotor unmanned aerial vehicle with computational fluid dynamics
Journal of Mechanical Science and Technology, 2006Co-Authors: Cheolwan Kim, Jindeog ChungAbstract:CFD simulation for one of tilt-rotor UAV configurations, TR-E2S1, was performed to investigate its aerodynamic characteristics. Control surfaces such as elevator and rudder were deflected and wing incidence angle was changed. Also aerodynamic stabilities were analyzed with the variation of pitch and yaw angles. The comparison of CFD with Wind Tunnel Test results reveals the same trends in the aerodynamic characteristics and stabilities. However 12% scale Wind Tunnel Test model is too small for accurate data collection and should build a high fidelity model for quantitative data comparison.
Jaeha Ryi - One of the best experts on this subject based on the ideXlab platform.
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noise reduction effect of airfoil and small scale rotor using serration trailing edge in a Wind Tunnel Test
Science China-technological Sciences, 2017Co-Authors: Jaeha Ryi, Jong-soo ChoiAbstract:This paper discussed a noise reduction effect of airfoil and small-scale model rotor by using attached serration trailing edge in the Wind Tunnel Test condition. In order to analyze the changes in the performance due to the inclusion of a serrated trailing edge designed to reduce noise, a 10 kW Wind turbine rotor was equipped with a thin serrated trailing edge. The restrictive condition for the serrated trailing edge equipped with the using of a 2D airfoil was examined through the using of a Wind Tunnel experiment after studying existing restrictive condition and analyzing prior research on serrated trailing edges. The aerodynamic performance and noise reduction effect of a small-scale model were investigated with the using of a serrated trailing edge. Moreover, the noise levels from the experiment were considered that the noise prediction method could be used for a full-scale rotor. It is confirmed that noise reduction effect is compared with Wind Tunnel Test data at the 2D airfoil and model rotor condition.
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Blockage effect correction for a scaled Wind turbine rotor by using Wind Tunnel Test data
Renewable Energy, 2015Co-Authors: Jaeha Ryi, Wook Rhee, Ui Chang Hwang, Jong-soo ChoiAbstract:Abstract This paper discusses the procedure of a blockage effect correction method involving small-scale Wind turbine rotor experimental data. To simulate the aerodynamic performance of full-scale rotors in the field, however, measured data from scaled model experiments need to be analyzed appropriately. One of the most important elements of such an analysis is a procedure to remove the blockage effect of the Wind Tunnel wall from the measured power data. In this paper, a correction algorithm proposed as part of Glauert's blockage effect correction method is used to process the data from a Wind turbine rotor Tested with three different Wind Tunnel sizes. Also, this study considered the modified blockage effect correction method, which has been used to process the rotor thrust data in closed-circuit Wind Tunnels and open-circuit Wind Tunnels. A small-scale rotor was Tested under the same operating conditions, i.e., the same advance ratio, rotating speed, rotor torque and speed of the Wind Tunnel. The small-scale Wind turbine rotor has a diameter of 1.408 m and a rotating speed according to the tip speed ratio. In each case, the effect of the blockage ratio and aerodynamic characteristics are determined using Wind Tunnel Test results and with a simple analytical correction method. The results of the modified correction method show that the aerodynamic performance levels during a Wind Tunnel Test are cleared by the blockage effect.
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a full scale prediction method for Wind turbine rotor noise by using Wind Tunnel Test data
AFORE, 2012Co-Authors: Jaeha Ryi, Jong-soo Choi, Seunghoon Lee, Soogab LeeAbstract:Abstract The development of a low-noise Wind turbine rotor and propeller is often cost-effective and is in fact a race against time to those who wish to build and Test a small-scale rotor instead of an expensive full-scale rotor. The issue of this approach has to do with the interpretation of Wind Tunnel model Test data in terms of both the frequency band and sound pressure level information for the noise scaling effect. This paper discusses a prediction method for the estimation of the noise generated from a full-scale Wind turbine rotor using Wind Tunnel Test data measured with both a small-scale rotor and a 2D section of the blade. The 2D airfoil self-noise and the scaled rotor noise were investigated with a series of Wind Tunnel experiments. Wind Tunnel data post-processing considered four aspects: removal of the Test condition effect, scaling to full scale, consideration of the Wind turbine rotor operating conditions, and the most important terms of full-scale rotor noise as adjustments to address the differences between the Wind Tunnel Test conditions and the full-scale operating conditions. A full-scale rotor noise prediction results comparison was performed by initially dividing the Test conditions into the condition of a 2D section noise Test and the condition of a small-scale rotor noise Test. Based on an airfoil section, the rotor was selected from a blade section at r / R = 0.75. The small-scale rotor was scaled down by a factor of 5.71 for the Wind Tunnel Test. Finally, the full-scale rotor noise data was compared with the Wind Tunnel Test data using a scaling estimation method.
Kasper Clemmensen - One of the best experts on this subject based on the ideXlab platform.
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Wind Tunnel Test on airfoil riso b1 18 with an active trailing edge flap
Wind Energy, 2010Co-Authors: Christian Bak, Mac Gaunaa, Peter Bjorn Andersen, Thomas Buhl, Per Juel Hansen, Kasper ClemmensenAbstract:A Wind Tunnel Test of the Wind turbine airfoil Riso-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 airfoil was Tested at Re = 1.66 × 106. Steady state and dynamic Tests were carried out with prescribed deflections of the ATEF. The steady state Tests showed that deflecting the ATEF towards the pressure side (positive β) translated the lift curve to higher lift values and deflecting the ATEF towards the suction side (negative β) translated the lift curve to lower lift values. Testing the airfoil for a step change of the ATEF from β = −3.0 to +1.8 showed that the obtainable Δcl was 0.10 to 0.13 in the linear part of the lift curve. Modeling the step response with an indicial function formulation showed that the time constant in the step change and in sinusoidal deflections in dimensionless terms was T0* = 0.6. Testing the ability of the ATEF to cancel out the load variations for an airfoil in sinusoidal pitch motion of ΔAOA = ±0.7 showed that it was possible to reduce the amplitude with around 80% from Δcl = 0.148 to Δcl = 0.032. Copyright © 2009 John Wiley & Sons, Ltd.
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Wind Tunnel Test on Wind turbine airfoil with adaptive trailing edge geometry
45th AIAA Aerospace Sciences Meeting and Exhibit, 2007Co-Authors: Dan Christian Bak, Mac Gaunaa, Peter Bjorn Andersen, Thomas Buhl, Per Juel Hansen, Kasper Clemmensen, Rene MollerAbstract:,A Wind Tunnel Test of the Wind turbine airfoil Ris oe-B1-18 airfoil equipped with an Adaptive Trailing Edge Geometry (ATEG) was carried out. The ATEG was made by piezo electric actuators attached to the trailing edge of a non-deformable airfoil and controlled by an amplifier. The airfoil was Tested at Re = 1.66x10 6 . Steady state and dynamic Tests were carried out with prescribed deflections of the ATEG. The steady state Tests showed that deflecting the ATEG towards the pressure side (posi tive β) translated the lift curve to higher lift values and deflecting the ATEG towards the suc tion side (negative β β β β) translated the lift curve to lower lift values. Furthermore, cd was almost unaffected by the ATEG actuation. Testing the airfoil for a step change of the ATEG f rom β=-3.0 to +1.8 showed that the obtainable Δcl was 0.10 to 0.13 in the linear part of the lift cu rve. Modeling the step response with an indicial function formulation showed that t he time constant in the step change and in sinusoidal deflections in dimensionless terms was T0* =0.6. Testing the ability of the ATEG to cancel out the load variations for an airfoil in si nusoidal pitch motion showed that it was possible to reduce the amplitude with around 80% from Δ Δ Δ Δcl=0.148 to Δcl=0.032.
Taehwan Cho - One of the best experts on this subject based on the ideXlab platform.
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Design and Performance Evaluation of Propeller for Solar-Powered High-Altitude Long-Endurance Unmanned Aerial Vehicle
Hindawi Limited, 2018Co-Authors: Donghun Park, Taehwan Cho, Yunggyo Lee, Cheolwan KimAbstract:Design, Wind Tunnel Test, computational fluid dynamics (CFD) analysis, and flight Test data analysis are conducted for the propeller of EAV-3, which is a solar-powered high-altitude long-endurance unmanned aerial vehicle developed by Korea Aerospace Research Institute. The blade element momentum theory, in conjunction with minimum induced loss, is used as a basic design method. Airfoil data are obtained from CFD analysis, which takes into account the low Reynolds number effect. The response surface is evaluated for design variables by using design of experiment and kriging metamodel. The optimization is based on desirability function. A Wind Tunnel Test is conducted on the designed propeller. Numerical analyses are performed by using a commercial CFD code, and results are compared with those obtained from the design code and Wind Tunnel Test data. Flight Test data are analyzed based on several approximations and assumptions. The propeller performance is in good agreement with the numerical and measurement data in terms of tendency and behavior. The comparison of data confirms that the design method, Wind Tunnel Test, and CFD analysis used in this study are practically useful and valid for the development of a high-altitude propeller
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Wind Tunnel Test for the nrel phase vi rotor with 2 m diameter
Renewable Energy, 2014Co-Authors: Taehwan Cho, Cheolwan KimAbstract:Abstract The aerodynamic performance of the ‘NREL Phase VI’ rotor with a 2 m diameter was Tested in the open jet Test section. The original rotor with a 10.06 m diameter was Tested in the NASA Ames Tunnel and the Test result was used as validation data for the computational model. The Reynolds number of the sectional airfoils in the original Test is around 1.0E6 which is too high for a conventional Wind Tunnel with a diameter less than 5 m. The Wind Tunnel Test to study the Reynolds number effect on the rotor performance from Re = 0.1E6 to Re = 0.4E6 was conducted in the KARI low speed Wind Tunnel with a 5 m × 3.75 m open jet Test section. The torque generated by the blade was directly measured by the sensor installed in the rotating axis. The variation of the Reynolds number was achieved by changing the rotational speed. Two surface conditions, free transition and forced transition were employed in this Test to study the surface trip effect. The Test results for the free transition condition show that the power coefficient, Cp gradually increases with the Reynolds number, but the Cp for the forced transition condition does not vary with the Reynolds number. The maximum Cp for the free transition is 0.30 and it decrease to 0.22 for the forced transition conditions at the Reynolds number 0.4E6. The downstream flow velocity measured by 5-hole probe in the Wind Tunnel Test was compared with BEMT calculation result. The comparison results show that the torque dependency on Reynolds number in the blade is mainly originated from the airfoil drag characteristics. A model to estimate the power of full scale blade was suggested based on these measurement results. The estimated power shows a good agreement with the full scale Test result.
