直连风洞/大堵塞比进气道流场复现与流动特性

Flow Field Reappearance and Flow Characteristics of Direct-Connect Wind Tunnel/Large Blockage Ratio Inlet

摘要:

为充分挖掘直连式风洞潜力,解决其无法复现自由射流试验冲压发动机进气道出口流场畸变难题,开展直连风洞/大堵塞比进气道流场复现与流动特性研究。研究结果表明:采用进气道截断技术与基于抽吸的流动控制技术,名义堵塞比 85%的直连风洞/大堵塞比进气道一体化构型能够实现风洞起动与进气道出口流场复现。一体化构型脉冲起动过程中产生向下游传播的起动激波,波后气流温度、压力阶跃式升高,气流以超声速向下游流动同时在扩张段进一步加速减压,形成了起动激波、二次激波与非常规接触面流场结构并向下游传播,二次激波增强传播速度下降；针对一体化构型,在最小二喉道位置采用抽吸措施解决起动问题,流场建立后抽吸率为 0.66%,以较小的抽吸流量解决直连风洞/大堵塞比进气道一体化构型的起动问题。

Abstract:

In order to fully tap the potential of direct-connect wind tunnel and overcome the problem that it can't repro-duce the distortion of flow field at the outlet of ramjet inlet in free jet test, the flow field reappearance and flow charac-teristics of direct-connect wind tunnel/inlet with large blockage ratio is studied. The research results show that the inte-grated configuration of directly connected wind tunnel with 85% nominal blockage and inlet with large blockage ratio can realize the wind tunnel start-up and the reappearance of the flow field at the inlet outlet by using the inlet truncation technology and the flow control technology based on bleed. In the pulse starting process of integrated configuration, the starting shock wave propagates downstream, and the temperature and pressure of the air flow increase step by step after the wave, and the air flow flows downstream at supersonic speed and further accelerates the decompression in the expan-sion section, forming the flow field structure of the starting shock wave, the secondary shock wave and the unconven-tional contact discontinuity and propagating downstream, and the speed of the secondary shock wave enhanced propaga-tion decreases; aiming at the integrated configuration, the starting problem can be solved by adopting bleed at the mini-mum second throat position, the bleed rate after the establishment of the flow field is 0.66%, and the starting problem of the integrated configuration of directly connected wind tunnel/inlet with large blockage ratio can be solved with a small bleed flow.