Performance Analysis Of Outside Stimulating Jet Oscillator

Flow control technology is one of the leading areas of research in fluid dynamics and has a wide application prospect in aerospace, marine and industrial fields. Hence, it is significant to study and develop the flow control technology.It changes the kinestate of fluid by applying a force, quality and heat on the moving fluid and more efficient method is to impose disturbance at the critical point of flow field. Flow control systems mainly rely on flow control actuators to produce micro-jet which coupled with the intrinsic mode of the mainstream body to control the flow.Through the external micro jet excitation, the high speed jet attached to the wall and oscillation obtaining the pulse flowing jet. The major advantages of this way to control the jet mode conversion are less energy loss and easier control the frequency and waveform, so it is particularly suitable for static gas wave refrigerator.This paper studies based on a new way to generate oscillation jet:abandon conventional self-oscillation mode, remove the self-excited channel beside the main channel, and import external micro-jets through narrow channel to make the main jet stream to switch. The frequency and intensity of external excitation can be proactively regulated, so that the oscillation frequency and switch speed of main jet can be better controlled.Based on the novel stimulating principle, we analyzed the outside stimulating jet oscillator with push-pull structure and its oscillation mechanism. The research was done by numerical simulation. The outside stimulating effect is achieved by setting the boundary condition with variable excitation function. In simulation, slightly trapezoidal and sinusoidal periodical excitation functions were used.Due to the restriction of different geometric parameters and operating parameters on the jet flow field, the interaction strength of controlling excitation and coupling efficiency are different. The oscillation characteristics and energy efficiency of external stimulating micro jet oscillator were studied and analyzed by numerical simulation method. The main research conclusions are as follows:(1) Lots of numerical simulation was made in allusion to characteristic dimensions of outside stimulating jet oscillator to study the effect of oscillation performance and the total pressure maintenance rate. The geometric parameter was optimized with obtaining the range of feature size in which the jet can stably oscillate and total maintenance rate was higher.(2) In this process, I paid more attention to the impact of two pairs of incentives. In different pattern of external excitations, oscillation characteristics and total pressure maintenance rate were examined at different size of incentive. When parallel and vertical incentive worked simultaneously or individually, we could get the trend of total pressure maintenance rate by changing parallel or perpendicular incentives’mouth width. We obtained when two pairs of incentives worked at the same time, the total pressure maintenance rate was highest and optimum size ratio of incentives was75%. The vertical excitation was closer to the bifurcated channel, the higher pressure we can get. The outlet total pressure maintenance rate reached90%.(3) Analyze the influence of external excitation modal to oscillation characteristics and total pressure retention, investigate the influence of the micro jet excitation function waveform and amplitude parameters to outlet total pressure and show that excitation function to retention of outlet total pressure has little effect and compared with trapezoid excitation, semi-sinusoidal excitation has a greater initial total pressure for3%.(4) Investigate the influence of external excitation modal to oscillation characteristics and total pressure retention after removing the subsequent incentive and comparing removing a single excitation with removing two excitations get a better effect.(5) Investigate the influence of fluid viscosity and geometric dimensions to outlet total pressure retention and show that with the increase of geometric dimensions, a maximum frequency attaching to the wall stably decreases and small dimensions have a smaller effect on frequency.