多喷嘴构型的轴对称氢氧加热器设计与仿真

为了使氢氧燃烧加热器满足自由射流试验台工作需要并获得均匀的出口气流参数,采用同轴剪切式7个喷嘴轴对称构型喷注器,利用CFD仿真软件对其进行了三维反应流场计算,燃烧模型采用氢氧单步反应模型,获得了设计工况下的参数.计算结果表明:燃烧效率随着中心喷嘴与外围喷嘴距离L与喷注面板半径R之比(L/R)的增大先上升后下降;喷注面板的温度随着L/R的增大而降低,最终维持在600K左右;加热器出口的氧气摩尔分数以及总温的均匀性基本不随着L/R变化而变化;出口主流区的马赫数在6左右满足设计要求.在各个喷嘴的影响区域大致相等时,加热器综合性能良好.氢氧速度比越大,完全燃烧所需区域越短,喷注面板温度越高.与单喷嘴、19个喷嘴的加热器比较发现7个喷嘴的构型较为合理. 

Design and numerical simulation of oxygen-hydrogen axisymmetric heater with multi-injector

In order to meet the working requirement and achieve the uniform parameters of hydrogen-oxygen heater outlet in free jet test stand, the heater was designed into axisymmetric structure, seven injectors with coaxial shear type for injection were adopted. The three-dimensional flow field was calculated by using the CFD simulation software with the hydrogen-oxygen single step reaction model and the parameters under design conditions were obtained. The results demonstrate that: with the increasing ratio of the center nozzle and the periphery nozzle distance L to the injection panel radius R(L/R), the combustion efficiency first increases and then decreases; the injection panel temperature decreases with the growth of L/R, ultimately reache around 600K; the uniformity of oxygen substance concentration and total temperature in heater outlet remains unchanged with L/R approximately; the Mach number in the outlet mainstream is around 6, which can satisfy the working requirement. The good comprehensive performance can be achieved when the influence area of each injector is approximately equal. The velocity ratio of hydrogen to oxygen gets higher, the area completing combustion will be shorter, and the injection panel temperature increases. Compared with the single-injector heater and nineteen-injectors heater, seven-injectors heater is reasonable.