内并联型进气道模态转换过程中流道间干扰特性研究

Interference Characteristics Between Flowpaths During Over-Under Type Inlet Mode Transition

关键词:  内并联型进气道  模态转换  数值模拟  干扰特性  流场失稳

Key words:  Over-under type inlet  Mode transition  Numerical simulation  Interference characteristics  Flow field instability

摘要:

针对组合动力进气道模态转换过程中存在的流道间干扰现象，采用数值模拟方法对典型内并联型进气道简化模型的模态转换过程中高/低速流道间的干扰特性展开了几种代表性案例研究，着重分析了高/低速流道气动耦合情况下的流场结构特征及其演化过程。结果表明：在本文研究的几种代表性状态中，当低速流道结尾激波位于低速流道内部时，高速流道节流至一定程度都将对低速流道形成干扰。该干扰现象出现后，高/低速流道的流动耦合，两流道的流量分配也随之发生变化，甚至导致了进气道流场的失稳。当分流板位于其总行程的四分之一时，高/低速流道间的干扰造成了进气道流场的失稳且失稳后的振荡流场会先后出现两个不同的发展时期：前一时期的振荡流场的振幅较大但频率较低，约为335Hz；后一时期的振荡流场的振幅较小但频率较高，约为880Hz。

Abstract:

Interference phenomenon between flowpaths exits during the inlet mode transition of combined cycle engine. To better understand the phenomenon， several representative case studies on the interference characteristics between high/low flowpaths during the mode transition process of a typical over-under type inlet were carried out by numerical simulation method. The flow field structure characteristics and evolution process under aerodynamic coupling of high/low flowpaths were emphatically analyzed. Results show that among the representative states studied in this paper， when the low speed flowpath terminal shock is inside the low speed flowpath， as the high speed flowpath throttles to a certain extent， it will produce interference to the low speed flowpath. After the interference， the flow of the two flowpaths is coupled， and the mass flow distribution of high/low speed flowpath will change. It may even cause the instability of inlet flow field. When the splitter is at one-quarter of its total travel， the interference between the high/low speed flowpaths causes the instability of inlet flow field， and there are two different development periods in the oscillating flow field. The amplitude of the oscillating flow field in the previous period is larger but the frequency is lower， about 335Hz. However， the amplitude of the oscillating flow field in the latter period is smaller but the frequency is higher， about 880Hz.