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本文通过风洞试验测量和计算流体动力学(Computational Fluid Dynamics,CFD)数值模拟的研究结果,分析了风洞洞壁对风力机翼型气动特性的影响.试验风洞为中国科学院工程热物理研究所(Institute of Engineering Thermophysics,IET)低速回流风洞,所选用的翼型为DU91-W2-250.数值模拟采用有洞壁、无洞壁、无侧壁三种方式进行计算,通过对比试验和数值计算结果验证了采用CFD数值模拟分析风力机翼型洞壁效应的可行性.通过数值模拟分析并与经典映像法及Maskell洞壁修正方法对比,得出:风洞中,上下壁面的存在使流动在风洞壁面形成一定厚度的边界层,造成气流的通道面积减小,来流有效速度增加,并引起翼型升力系数C_l和阻力系数C_d增加;风洞侧壁诱导翼型段表面的展向流动、抑制了翼型表面的流动分离,减小了翼型弦向流动速度,引起翼型升力系数减小,阻力系数增加;小攻角时风洞侧壁对翼型表面流动的影响可以忽略,翼段表面流动保持二维性,大攻角时风洞侧壁干扰效应显著,其影响程度超过风洞上下壁面,与无洞壁相比,风洞壁的存在使升力系数减小,阻力系数增加;经典映像法及Maskell方法因未考虑洞壁边界层的影响,并不适用于风力机翼型大攻角流动时的洞壁效应修正问题,大攻角修正时应考虑风洞侧壁影响,对升力系数给予增量;同时对于大攻角流动,翼型本身流动已不具有二维性,其气动性能的测量应采用多截面压力测量或天平测力方法.
In this paper, the influence of wind tunnel on the aerodynamic characteristics of wind turbine airfoil is analyzed by the results of wind tunnel test and Computational Fluid Dynamics (CFD) numerical simulation.The experimental wind tunnel is the study of Engineering Thermophysics of Chinese Academy of Sciences (Institute of Engineering Thermophysics, IET) low-speed return wind tunnel, the selected airfoil DU91-W2-250 numerical simulation using a hole wall, no hole wall, no side walls were calculated in three ways through the comparison test and The numerical results verify the feasibility of using CFD numerical simulation to analyze wind turbine airfoil effect.Compared with the classical image method and Maskell correction method, the numerical simulation results show that the presence of upper and lower wall The flow creates a certain thickness of boundary layer on the wall of the wind tunnel, resulting in a decrease of the flow passage area and an increase of the effective velocity of the incoming flow, resulting in an increase of the lift coefficient C_l and the drag coefficient C_d of the airfoil. Flow restrains the flow separation on the airfoil surface, reduces the chordal flow velocity of the airfoil, decreases the lift coefficient of the airfoil and increases the drag coefficient, while the small angle of attack The influence on the airfoil surface flow is negligible, the flow on the surface of the airfoil maintains two-dimensionality, and the interference effect on the sidewall of the wind tunnel is significant when the angle of attack is large, which affects the upper and lower walls of the wind tunnel more than the non- The lift coefficient decreases and the drag coefficient increases. The classical image method and the Maskell method are not suitable for the correction of the wall effect when the airfoil flows at a large angle of attack, because the influence of the boundary layer on the wall is not considered. For the angle correction, the effect of the sidewall of the wind tunnel should be considered and the lift coefficient should be increased; meanwhile, the flow of the airfoil itself does not have two-dimensionality for large-angle of attack flow. The multi-section pressure measurement or balance measurement Force method.