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.