Three Dimensional Separation with Spiral-Focus in a Decelerating Duct Flow (Effect of Asymmetric Inlet Boundary Layer Thickness)

An experimental apparatus was developed to study the three dimensional separated flow with spiral-foci.The internal decelerating flow was generated by the air suction from a side wall to produce the separation on an opposite-side wall.The relation between the upstream boundary layer and the generation of spiral-foci in the separation region was observed by a tuft method.As a result,it was clarified that the spiral-focus type separaton could be produced on the side wall and its behavior was closely related to the vortices supplied into the separation region from the boundary layer developing along top wall or bottom one.

直升机红外抑制器结构参数对抑制器性能影响的数值和实验研究

在模型实验验证的基础上,采用数值模拟的方法,研究了一种红外抑制器二元混合管结构参数对红外抑制器整体气动性能和温度场的影响。研究结果表明:在研究参数范围内,随着二元混合管出口宽度的增大,二元引射喷管引射系数先上升后下降,弓形挡板冷端平均温度增幅为24%;随着二元混合管扩张角增大,引射系数下降,弓形挡板冷端平均温度增幅为3%;适当延长混合管直段长度,引射系数先缓慢上升而后下降,弓形挡板冷端温度变化较小。能否有效利用主流动量、抑制主流的流动分离是提高引射系数的关键。弓形挡板冷端表面温度受弓形挡板内部引射气流、弓形挡板冷端下游滞止涡和二元混合管窄边出口的回流冷气三者共同影响。