The aerodynamic performance of blunt trailing edge airfoils was investigated. The flow fields around the modified NACA64-418, which consists of the tip blade of the wind turbine and Mexico model of IEA wind, were analyzed. To imitate the repaired airfoil, the original NACA64-418 airfoil, a cambered ...
The aerodynamic performance of blunt trailing edge airfoils was investigated. The flow fields around the modified NACA64-418, which consists of the tip blade of the wind turbine and Mexico model of IEA wind, were analyzed. To imitate the repaired airfoil, the original NACA64-418 airfoil, a cambered airfoil, is modified by the adding thickness method, which is accomplished by adding the thickness symmetrically to both sides of the camber line. The thickness ratio of the blunt trailing edge of the modified airfoil, $t_{TE}/t_{max}$, is newly defined to analyze the effects of the blunt trailing edge. The shape functions describing the upper and lower surfaces of the modified NACA64-418 with blunt trailing edge are obtained from the curve fitting of the least square method. To verify the accuracy of the present numerical analysis, the results are first compared with the experimental data of NACA64-418 with high Reynolds number, $Re=6{\times}10^6$, measured in the Langley low-turbulence pressure tunnel. Then, the aerodynamic performance of the modified NACA64-418 is analyzed. The numerical results show that the drag increases, but the lift increases insignificantly, as the trailing edge of the airfoil is thickened. Re-circulation bubbles also develop and increase gradually in size as the thickness ratio of the trailing edge is increased. These re-circulations result in an increase in the drag of the airfoil. The pressure distributions around the modified NACA64-418 are similar, regardless of the thickness ratio of the blunt trailing edge.
The aerodynamic performance of blunt trailing edge airfoils was investigated. The flow fields around the modified NACA64-418, which consists of the tip blade of the wind turbine and Mexico model of IEA wind, were analyzed. To imitate the repaired airfoil, the original NACA64-418 airfoil, a cambered airfoil, is modified by the adding thickness method, which is accomplished by adding the thickness symmetrically to both sides of the camber line. The thickness ratio of the blunt trailing edge of the modified airfoil, $t_{TE}/t_{max}$, is newly defined to analyze the effects of the blunt trailing edge. The shape functions describing the upper and lower surfaces of the modified NACA64-418 with blunt trailing edge are obtained from the curve fitting of the least square method. To verify the accuracy of the present numerical analysis, the results are first compared with the experimental data of NACA64-418 with high Reynolds number, $Re=6{\times}10^6$, measured in the Langley low-turbulence pressure tunnel. Then, the aerodynamic performance of the modified NACA64-418 is analyzed. The numerical results show that the drag increases, but the lift increases insignificantly, as the trailing edge of the airfoil is thickened. Re-circulation bubbles also develop and increase gradually in size as the thickness ratio of the trailing edge is increased. These re-circulations result in an increase in the drag of the airfoil. The pressure distributions around the modified NACA64-418 are similar, regardless of the thickness ratio of the blunt trailing edge.
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가설 설정
1. The drag of the airfoil increase, but the lift increases insignificantly as tTE/tmax is increased.
3. The pressure distributions around the airfoil are similar regardless of tTE/tmax except for the trailing edge.
제안 방법
8 represent good agreement between the computed and experimental results. All of the calculations in this paper for the modified NACA64-418 airfoil with the blunt trailing edge are carried out on the basis of this accuracy and use the same flow conditions to determine the effects of the blunt trailing edge on the aerodynamic characteristics.
In this study, the 2-D aerodynamic performances of modified NACA64-418 airfoils with a blunt trailing edge are investigated. These airfoils are obtained by the adding thickness method and are imitated for the purpose of repairing the damaged tip blade of the wind turbine, as shown in Fig.
The modified NACA64-418 airfoil created by the adding thickness method is imitated for the repair airfoil. In this study, the 2-D aerodynamic performances of the airfoil with a blunt trailing edge are investigated according to the thickness ratio of the blunt trailing edge, tTE/tmax. The numerical results obtained are as follows:
대상 데이터
5. Airfoils with ratios (tTE/tmax) of 10%, 20%, and 30% and the original NACA64-418 airfoil with tmax = 18%. Fig.
Especially, the Mexico model of IEA wind [1] consists of three different types of airfoils for the shape of wind turbine blade. This model adopts the DU91-W250 airfoil at the hub blade, RISO-A1-21 airfoil at the middle blade, and NACA64-418 airfoil at the tip blade as depicted in Fig. 2. Schepers et al [1] conducted a wind tunnel experiment for the Mexico rotor blade to measure the characteristics of the rotating airfoil.
데이터처리
5) 15 airfoil (adding thickness method). The aerodynamic performances of these airfoils were studied by ANSYS CFX. The result showed that the adding thickness method produces larger maximum lift and critical angles of attack than the cutting off method.
이론/모형
For the numerical analysis in this study, the commercial program Pointwise is used for the shape modeling and grid generation and ANSYS Fluent is used for carrying out the aerodynamic analysis.
1). The surface curve line of this modified airfoil is designed by the adding thickness method. The shape functions describing the upper and lower surface of the modified NACA64-418 are obtained from the curve fitting of the least square method with the commercial program, Maple.
참고문헌 (13)
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H. A. Smith and R. F. Schaefer, Aerodynamic characteristics at Reynolds numbers of 3.0x106 and 6x106 of three airfoil sections formed by cutting off various amount from the near portion of the NACA0012 airfoil section, Langley Aeronautical Laboratory, USA, NACA TN 2074, 1950.
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