| The study of subsonic impinging jet has been a popular subject for many years, not only because of its importance in fundamental research, but also because of its importance in engineering applications. For STOVL (Short Take-off and Vertical Landing)aircraft, the high-speed exhaust from the jet engine is deflected by impingement on the flaps to create extra lift during take-off. Fatigue due to excessive dynamic loading on flaps and high levels of noise radiation are among problems encountered in such designs. Also, the study of subsonic impinging jet provides theoretical basis for NSV (Non-synchronous Vibrations) problem in axial-flow Compressor.Based on the former study of the resonant impinging jet, the paper designs the test bed of subsonic impinging jet and makes preliminary experiment study of the feedback theory of the resonant impinging jet. It makes a foundation for future research. The main works in this thesis as follows:The test bed of subsonic impinging jet is designed, including pneumatic system, pressure regulating valve, difrusers with wide-angle, rectifying section and contracting section. The test bed can provide stable air flow for the speed of Mach 0.3 to Mach 0.9.Based on the feedback theory of the resonant impinging jet, the paper provides experiment study for the vortex shedding frequency and the impinging jet resonant frequency at L/D=4.The study of the vortex shedding frequency shows that the vortex shedding frequency increases as the jet velocity; The study of the impinging jet resonant frequency at L/D=4 shows that the resonant frequency is 1750Hz, and verifies that the coherence structures impinging on the rigid plate at 1<r/D<1.5. |
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