等离子体合成射流能量效率及工作特性研究

Energy efficiency and performance characteristics of plasma synthetic jet

基于等离子体激励器工作过程中气体放电的焦耳加热作用,并结合局部热力学平衡等离子体物理假设,开展了等离子体合成射流三维唯象数值研究,获得了完整工作周期内等离子体合成射流流场发展演变过程.研究结果表明,单次能量沉积建立的自维持周期性射流中存在有实现激励器腔体"充分"回填的最大脉冲工作频率——饱和频率.大的能量沉积、小的激励器出口直径和相同腔体体积下大的径高比都可以产生速度更高的射流,而射流速度的提高会伴随有饱和频率的降低.一个饱和周期内,最多约有16%的初始腔内气体喷出,吸气复原仅能实现初始腔体质量90%左右的回填.一个大气压条件下,容性电源供能的等离子体合成射流激励器电能向气体热能和射流动能的转化效率分别约为5%和1.6%.

Based on the Joule heating effect of gas discharge in the working process of the plasma actuator, the plasma synthetic jet is simulated with a three-dimensional phenomenological model, under the assumption of local thermodynamic equilibrium plasma.The flow field evolution process of the plasma synthetic jet during a whole cycle is obtained. The results show that in the self-sustained periodical jet built by a single energy deposition, there is a maxium pulse frequency--saturated frequency which could relaize that the cavity is recovered sufficiently. Large energy deposition, small exit orifice diameter and high diameter-height ratio with the same cavity volume could induce higher speed jet, and the increase of the jet speed occurs concurrently with the decrease of the saturated frequency. During a saturated cycle, up to 16% of the mass in the cacity is expelled, but the recovery can only achieve about 90% of the initial mass in the cavity. Plasma synthetic jet actuator is supplied by a capacitive power supply at atmospheric pressure, the fractions of power that go into gas heating and jet kinetic energy are 5% and 1.6% respectively.