壁式与径向组合稳定器的流动与点火特性研究

Flow and Ignition Characteristics of Wall Combined with Radial Flame-Holder

为实现多模态冲压燃烧室全工况范围内的可靠点火及稳定燃烧,提出一种壁式稳定器和径向稳定器组合设计方案,以提高在高速来流下的点火性能。数值研究了壁式+径向组合稳定器在不同结构参数下的流动特性,试验测量不同结构组合稳定器的点火极限,并利用回流率、质量交换率以及流动停留时间等参数揭示稳定器结构参数对点火性能的影响。研究结果表明:台阶高度及径向稳定器倾角通过改变流场结构进而影响点火性能。台阶高度越高,回流区结构越大,点火极限越低;在与径向稳定器组合后,值班稳定器内回流区沿径向稳定器向主流冷流区延伸,散热增强,同时点火释放能量易被径向回流带出值班区,因此点火极限增加。随着径向稳定器前倾角度增加,回流区与主流质量交换增加,流动停留时间缩短,导致点火性能的降低。

In order to achieve reliable ignition and stable combustion in the full working range of dualmode ram combustion,a design scheme of wall flame-holder combined radial flame-holder is proposed to improve the ignition performance under high-speed flow.The flow characteristics of the wall combined with radial flame-holder under different structural parameters were studied by the numerical calculation,and the ignition limits under different structures were obtained through experimental research,and the effects of flame-holder structure parameters on ignition performance were revealed by using such parameters as reflux rate,mass exchange rate and flow residence time.The results show that the height of the cavity and the inclination of the radial groove affect the ignition performance by changing the flow field structure.The higher the height of the step,the larger the structure of the recirculation zone and the lower the ignition limit is.After being combined with the radial flame-holder,the recirculation zone in the pilot flame-holder extends along the radial flame-holder to the mainstream cold flow zone,heat dissipation is enhanced,and the ignition release energy is easily carried out of the pilot-zone by the radial flame-holder,so the ignition limits increase.As the forward inclination angle of the radial flame-holder increases,the mass exchange between the recirculation zone and the mainstream increases,and the flow residence time is shortened,resulting in a decrease in ignition performance.