燃气发生器低频非稳态燃烧统计分析

针对冲压发动机地面试验需求,设计燃气发生器,通过试验统计研究其燃烧稳定性特征。结果表明:该燃气发生器发生低频非稳态燃烧的概率为32.7%,存在两种振荡形态。一种存在振荡主频,即低频不稳定燃烧;另一种没有主频,燃烧形态为粗暴燃烧。粗暴燃烧发生概率高且与余氧系数存在较强的相关性,低频不稳定燃烧发生概率低。两种形态的振荡能量分布位置不同。

Investigation of low frequency unsteady combustion of gas generator based on the statistical analysis

The gas generator is the key equipment of scramjet ground test system. Unsteady combustion occurred several times in hot tests of a certain gas generator. Statistics found that times of unsteady combustion accounted for 32.7% of the total number of hot tests. The analysis method in time domain and frequency domain was adopted to treat the pressure data and obtained that all unsteady combustion occurred belonged to low frequency oscillation (the frequency is less than 100Hz). There were two kinds of spectrum forms. One has dominant frequency crest. The pattern of this unsteady combustion is low frequency combustion instability or chuffing. For the other one, there was no dominant frequency crest namely rough combustion. It was found that the probability that occurred rough combustion was concerned with excess oxidizer coefficient. There were certain range of excess oxidizer coefficient that occurred high probability the rough combustion. The low frequency combustion instability occurred with lower probability. Apart from the difference of spectrum form of oscillation, the energy distribution of these two unsteady combustion is different, too.