多级波瓣引射混合器气动性能数值研究

Numerical study on aerodynamic performance of multi-stage lobed mixer-ejector

通过三维CFD计算,研究了在特定混合管长径比和截面比下,单、双级波瓣引射混合器性能随基本结构参数变化的规律和差异.研究结果表明:双级波瓣引射混合器的引射系数随波瓣扩张角和主流速度的增加而增加,双级波瓣引射混合器的第1级引射系数要高于单级波瓣引射混合器,且总引射系数比单级波瓣引射混合器高出100%;主流流速增加,流向涡强度和速度环量相应增大;单级波瓣引射混合器沿程流向涡峰值强度不断减弱,但速度环量先增加后减小;双级波瓣引射混合器沿程流向涡强度和速度环量则同时逐渐减小,且在1级引射中减小速度要快些;由于主流速度增加或扩张角增大造成的主流过早附壁使得热混合效率减小;尽管双级波瓣引射混合器混合管内热混合效率增加放缓,但与单级波瓣引射混合器相比,混合管出口处热混合效率还是有6%的增加.

Based on three dimensional CFD of single/double-stage lobed mixer-ejector with fixed mixing duct area ratio and length ratio,the effects of fundamental structure parameters on pumping performance were investigated.The results showed that the pumping ratio of double-stage lobed mixer-ejector increased when main stream velocity or lobe diffusion angle rose.The first stage pumping capacity for double-stage lobed mixer-ejector was stronger than single-stage lobed mixer-ejector,meanwhile the total pumping ratio of doublestage lobed mixer-ejector was 100% superior to that of single-stage one.Besides,the maximum vorticity and the velocity circulation became larger with the increase of primary flow velocity.In the direction of main stream,the maximum vorticity of single-stage mixer declined gradually,while the velocity circulation firstly increased and then decreased.However,in the double-stage lobed mixer-ejector,both maximum vorticity and velocity circulation decreased along main stream,with a much higher decreasing speed in the first stage nozzle.What＇s more,the thermal mixing efficiency declined as primary flow was attached to wall much earlier due to the increase of main stream velocity or lobe diffusion angle.For doublestage lobed mixer-ejector,the thermal mixing efficiency at mixing duct exit section was 6%superior in comparison with single-stage one,though the thermal mixing efficiency of doub-le-stage lobed mixer-ejector rose at a low speed along mixing duct.