槽壁几何参数对跨声速风洞流场品质的影响

Effect of geometry parameters on flow field quality in a transonic slotted wind tunnel

采用数值模拟方法研究了再入片开角、槽腔扩开角和开槽形状对跨声速槽壁风洞流场品质的影响。在数值模拟方面,介绍了对应的出入口边界条件设置方法,通过量纲分析得出适用于内流问题的相似参数。研究结果表明:再入片关闭工况下,其前缘处形成了声速喉道,难以建立稳定的试验段超声速流场;再入片打开工况下,试验段流场的不利扰动主要来自于从驻室到试验段的槽壁出流现象,其根源是驻室涡系产生的垂直于槽壁方向的冲击气流,较大的槽腔扩开角对冲击气流有一定的阻挡作用。槽壁各部件对试验段流场品质的影响均是通过增强或抑制槽壁出流来实现的,其中开槽平面形状的影响尤为突出。采用基于自由变形(FFD)的优化设计方法得到了适用于试验段马赫数0.8到1.2状态的开槽形状,优化结果显示初始构型中存在的槽壁出流大部分得到消除,模型区马赫数均方差降低了一个量级,证明了该方法的合理性与实用性。

Numerical simulation method is applied to studying the effect of the re-entry flap angle,slot diverging angle and slot shape on the flow field quality in a transonic slotted wind tunnel.Boundary conditions at the inlet and outlet of the tunnel are introduced,and also,similarity parameters are obtained through dimensional analysis.The results show that a sonic throat will be formed at the leading edge if the re-entry flap is closed,leading to the inability to establish stable supersonic flow at the test section.When the re-entry flap is open,the slot outflow which comes from the plenum is the main disturbance source of the flow field and could be wakened with a larger slot diverging angle.All the components affect the flow field quality by strengthening or wakening the slot outflow while the slot shape is the most sensitive.An optimization approach based on free form deformation（FFD）method is adopted and therefore a slot shape which is applicable to cases from 0.8to 1.2Mach number in test section is obtained.Results of the optimization show that most of the slot outflow which occurs in the original configuration has been eliminated and the mean square error of Mach number distribution at the test section is reduced by an order of magnitude,proving that the optimization approach is reasonable and practicable.