非均匀超声来流矩形隔离段内流场实验

Experimental investigation on internal flow in rectangular isolator under non-uniform supersonic flow

关键词:  冲压喷气发动机  超音速燃烧  非均匀流  隔离器  内流空气动力学  激波

Key words:  Ramjet engine  Supersonic combustion  Nonuniform flow  Isolator  Internal aerodynamics  Shock wave

摘要:

针对超燃冲压发动机隔离段的非均匀进口条件设计了隔离段实验风洞,通过测量隔离段壁面压力和拍摄流场纹影照片研究了矩形隔离段内激波/紊流附面层相干流场。研究发现,隔离段进口的非均匀流使隔离段流场压升特征与附面层发展规律与均匀进口的隔离段流动有显著差异。用截面当量直径取代Waltrup公式中的圆管直径可以取得较好的吻合效果。在进口马赫数小于2时,升高同样的压力,非均匀进口隔离段产生的激波串长度比Waltrup公式预测的长度要长。纹影仪观察发现隔离段内激波存在严重的振荡现象。

Abstract:

The wind tunnel was designed with non-uniform incoming flow for investigating the airflow in scramjet isolator. Shock wave/turbulent boundary-layer interactions in rectangular isolator were investigated by using wall pressure measurement and schlieren photography. It is indicated that the characteristics of pressure rise and boundary-layer development in isolator under a non-uniform incoming airflow is distinctly different from that under a uniform incoming airflow. By replacing the cylindrical isolator diameter with equivalent diameter of the rectangular isolator, a preferable agreement between experimental data and results from Billig -Waltrup correlation was obtained. For the same back pressure and inflow condition, the shock train length in isolator under a non-uniform incoming airflow is longer than that predicted by the Billig-Waltrup correlation, the difference is especially remarkable when the incoming flow Mach number is less than 2. It is observed that the shock oscillation is serious in isolator by the schlieren arrangement.