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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2017, Vol. 38 ›› Issue (11): 121146-121146.doi: 10.7527/S1000-6983.2017.121146

• Fluid Mechanics and Flight Mechanics • Previous Articles     Next Articles

Test of low Mach number unstart and restart processes of hypersonic inlet

WANG Chenxi1, TAN Huijun1, ZHANG Qifan1, SUN Shu2   

  1. 1. Jiangsu Province Key Laboratory of Aerospace Power System, College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;
    2. College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
  • Received:2017-01-18 Revised:2017-04-11 Online:2017-11-15 Published:2017-04-10
  • Supported by:

    National Natural Science Foundation of China (11532007)

Abstract:

To enrich the understanding of the mechanism for hypersonic inlet unstart,a wind tunnel test is conducted to investigate the low Mach number unstart and restart of a truncated two-dimensional hypersonic inlet. By varying the inlet angle of attack and the downstream choking degree, the variation of the inlet flow Mach number and heat release of combustion in real flight conditions are simulated in this test. The high-speed Schlieren imaging technology and time-resolved pressure measurements are used to record the instantaneous flow pattern and surface pressure signals. The results show that during the unstart process at low Mach number, the separation bubble induced oblique shock is influenced by the oscillation characteristic of the separation bubble, and oscillates slightly around the cowl lip to introduce a type of small-amplitude disturbance without base frequency. This disturbance gradually disappears with the increase of the Mach number and restart of the inlet. Hysteresis of swallow of separation bubble is also observed in the test. When the inlet recoveries from the little buzzle state to the start state, the separation bubble cannot be fully swallowed due to the presence of high pressure downstream during the restart process, and exhibits as a small-amplitude oscillation similar to the one in low Mach number unstart process. The oscillation does not disappear until the inlet exit is fully open and the separation bubble in the entrance is swallowed simultaneously, and then the inlet returns to start successfully.

Key words: hypersonic inlet, low Mach number, unstart, restart, hysteresis

CLC Number: