脉冲气举用自振空气射流研究

Research on self-excited oscillation air jets for pulse airlift

为了探究自激振荡空气射流发生机理以及最佳结构参数和运行参数,基于流体自激振荡原理,以Helmholtz共振腔作为物理模型,着重分析了自激振荡脉冲空气射流的关键影响因素;利用FLUENT软件对自激振荡脉冲空气射流内外瞬时流场进行数值模拟,获取其流动特性;通过试验得到了在不同长径比L/d1和不同工作压力下,自激振荡空气射流的压力脉动特性。结果表明,试验结果与数值仿真结果吻合良好;长径比与工作压力共同影响射流脉冲效果,减小工作压力将导致能量交换能力变差,削弱射流振荡效果;当工作压力为0.4 MPa时,射流流速大,剪切层卷吸率高,脉冲效果最好;长径比存在一最佳值,使得射流振荡效果最好,当L/d1=7.5左右时,射流的脉动效果最佳。研究结果可为自振空气射流应用于脉冲气举效率提升提供参考。

In order to explore the mechanism of self-excited oscillating air jet and the optimal structural and operational parameters,based on the principle of fluid self-excited oscillation,Helmholtz resonant cavity was used as the physical model to focus on analyzing the key influencing factors of self-excited oscillating pulse air jet;Fluent software was used to numerically simulate the instantaneous flow field inside and outside the self-excited oscillating pulse air jet,and obtain its flow characteristics;The pressure pulsation characteristics of self-excited oscillating air jet under different aspect ratios L/d1 and working pressures were obtained through experiments.The results indicate that the experimental results are in good agreement with the numerical simulation;The aspect ratio and working pressure jointly affect the jet pulse effect.Reducing the working pressure will lead to poor energy exchangeability and weaken the jet oscillation effect;When the working pressure is 0.4 MPa,the jet flow rate is high,the shear layer suction rate is high,and the pulse effect is the best;There exists an optimal value for the length to diameter ratio,which results in the best oscillation effect of the jet.When L/d1=7.5,the pulsation effect of the jet is optimal.The research results can provide reference for the application of self-oscillating air jets in improving the efficiency of pulse gas lift.