高升力下二维构型阻力准确测量研究

Research of measurement method of two dimensional configuration drag test in wind tunnel in case of high lift

翼型风洞试验阻力测量常使用尾迹流场测量积分求取阻力的方法,但各积分公式均建立在一定的假设基础上,有一定适用范围。在多段翼型流场N-S方程数值模拟和风洞试验的基础上,研究高升力情况下低速风洞阻力精确测量技术。通过N-S方程数值模拟求解多段翼型绕流场,分析尾迹流场的特点和常规风洞试验阻力计算公式推导时所作假设,提出新的更为准确的型阻计算公式;利用多段翼型绕流的数值模拟结果,积分表面压力和摩擦力求得翼型的气动特性,并利用计算得到的尾迹流场信息按照常规和新提出的风洞试验型阻计算公式计算阻力,将三者进行比较,检验提出的新型阻计算公式的准确性;通过风洞试验检验数值模拟得到的流场特点和新型阻计算公式。研究表明:在高升力条件下,传统型阻计算公式有很大的局限性,必须进行改进;提出的考虑尾迹区流动特点的新型阻计算公式能够得到更准确的阻力值。

Computational fluid dynamics and wind tunnel test are two main technical means to examine the aerodynamic performance of airfoil and two dimensional configuration.Two dimensional wind tunnel tests commonly use wake flow field measurement to integrate for drag of airfoil or two-dimensional configuration,but the integral formulas are based on certain assumptions and of certain bounds of application.In this paper,based on Navier-Stokes equations numerical simulation and two dimensional wind tunnel testing,the drag measuring technique for high lift configuration in low speed wind tunnel is researched.Navier-Stokes equations is solved for the flow around a multi-element airfoil,the wake flow characteristics behind the multi-element airfoil and the assumptions for conventional drag measuring method are analyzed,then a new more precise drag formula for two dimensional wind tunnel test is put forward.Based on the simulation results of multi-element airfoil flow,it＇s aerodynamic performance is obtained respectively by integrating the surface pressure and friction drag,and computing with the information of wake flow according to conventional and newly proposed drag calculation formulas,and the three results are compared to verify the accuracy of the new drag formula.The wind tunnel test is carried out to ascertain the accuracy of the new drag formula.It is shown from the results that in the high-lift case the conventional drag formula with the wake information is of many limitations and must be improved,and the new drag formula presented in this paper is more accurate because of consideration of the wake flow characteristics of airfoil or two-dimensional configuration.