Abstract: The dump diffuser and its performance affect the fluid field and pressure loss of combustor.Keep the inlet Mach number of prediffuser invariable(0 265),simulation and experiments were carried out to obtain the regularity of the total pressure loss varying with the relative dump gap(1 2～3 0) which was changed through changing the position of prediffuser and combustor liner respectively.Investigation shows that when δ is too small,the airflow at the exit of the prediffuser turns urgently,the airflow separates at the exit of prediffuser and splits urgently too.So exists the optimal relative dump gap( δ =1 8-2 0) to achieve the minimum total pressure loss(1 6%～1 75%).

Key words: Dump diffuser;Dump gap;Total pressure drag

摘要： 通过数值计算和试验两种方法研究了短突扩扩压器突扩间隙与压力损失间的变化规律并探讨了变化机理。研究在前置扩压器结构和进口马赫数保持不变的前提下 ,分别通过改变前置扩压器和火焰筒的位置两种方式改变突扩间隙 ,研究总压损失系数的变化规律。结果表明 :在本研究参数范围内 ,当突扩间隙较小时 ,前置扩压器出口气流拐弯剧烈 ,流线是非光滑的 ;相反 ,则会导致前置扩压器出口气流的二次分离 ,在突扩区形成两个涡 ,而且气流拐弯剧烈、流量分配不均匀。因而存在有最佳的相对突扩间隙 (δ =1 8～ 2 0 ) ,使得总压损失最小( 1 6%～ 1 75 % )。

关键词: 突扩扩压器;突扩间隙;总压损失