非对称来流隔离段流动特性研究

Investigation of flow in isolators under asymmetric incoming airflow

关键词:  超燃冲压发动机  非对称来流~+  隔离段设计~+  内流空气动力学  激波  风洞实验

Key words:  Supersonic combustion ramjet engine  Asymmetric incoming flow~+  Isolator design~+  Internal aerodynamics  Shock wave  Wind tunnel test

摘要:

设计了针对非对称超声速来流矩形隔离段流场研究的直联式试验风洞,在模拟进气道出口流场的各种非对称进口条件下进行了吹风试验。研究发现,随隔离段进口流动非对称程度的增加,在相同的进出口压比下,激波串长度增加;在同样的激波串长度下,隔离段耐受反压的能力下降。首次提出表征非对称入口条件的非对称度因子Dδ和Dθ,并将因子Dθ引入到矩形隔离段激波串长度计算公式,得到了预测非对称来流隔离段激波串长度的新公式,该公式预测激波串长度与实验结果吻合良好。

Abstract:

In order to simulate the actual flowfield at the exit of supersonic/hypersonic inlet,the flow in scramjet isolator is investigated under asymmetric incoming flow.A wind tunnel is designed under asymmetric incoming flow and the compression fields in the isolator have been investigated by wall static and pitot pressure measurements and by schlieren photography.Three incoming Mach numbers are considered,Mach 1.5,Mach 1.8 and Mach 2 respectively.The results indicate that the increase of the asymmetry of the flow at isolator entrance will lead to the increase of the shock train length in isolator for a given pressure ratio.Based on an analysis of flow asymmetry effect at isolator entrance on shock train length,a modified correlation is proposed to calculate the length of shock train.The predicted results of the proposed correlation show good agreement with experimental results.