喷注方案对圆形超燃冲压发动机性能的影响研究

Effects of Injection Scheme on Round Scramjet Performance

关键词:  喷注方案  超燃冲压发动机  圆形燃烧室  推力性能  壁面热流

Key words:  Injection scheme  Scramjet  Round combustor  Thrust performance  Wall heat flux

摘要:

在飞行马赫数Ma=6，总当量比为1.0条件下，采用三维数值模拟研究了不同喷注位置煤油当量比分布对双凹腔圆形发动机推力性能和壁面热流的影响。喷注位置包括支板壁面喷注K1，隔离段出口壁面喷注K2，第一凹腔尾缘壁面喷注K3以及第一扩张段壁面喷注K4。结果表明，K1注油当量比大小直接影响燃烧室内的燃烧模态和流道中心燃烧。为了保证发动机推力性能，K1注油须达到一定量，促使流道燃烧处于亚燃模态，且流道内具有较强的中心燃烧。为优化发动机壁面热流环境，剩余燃料需要在K2，K3和K4分散注入。K2和K3注油当量比大小同时影响第一凹腔燃烧性能，其中K2注油当量比降低，推力性能下降，但壁面热流性能提高，而适当增加K3喷注煤油，有利于提高推力性能。增加K4注油，第二凹腔及其之后流道区域燃烧增强，发动机推力性能和热流性能均提高。通过分析各注油位不同当量比分布对发动机力热性能的影响规律，最终获得了力热性能较优的注油当量比分配方案，此时K1～K4注油当量比大小依次为0.6，0.1，0.1，0.2。

Abstract:

A three dimensional numerical study was carried out to investigate the effects of injection scheme on the thrust and wall heat flux performance of a round scramjet with dual-cavity configuration. The results were obtained with flight Mach number of 6.0 and the total kerosene equivalence ration of 1.0. The injectors were located on the wall of four different regions including the strut K1， the isolator outlet K2， the first cavity trailing edge K3 and the first expansion section K4. Results show that the equivalence ratio of K1 directly affects the combustion mode and the center combustion performance. In order to satisfy the scramjet thrust performance， a certain value of fuel mass should be injected from K1 to induce a subsonic combustion mode and strong center combustion. Moreover， in order to optimize the scramjet thermal environment， the excess fuel should be injected from another three injectors K2~K4. It is found that the equivalence ratio of K2 and K3 affect the combustion performance of the first cavity at the same time. With the decreasing of K2 equivalence ratio， the thrust is decreased while the thermal environment is improved， and with some fuel injected from K3，the thrust increases. Also， with the increasing of K4 equivalence ratio， the thrust and wall heat flux performance are improved as the combustion in the second cavity and the area behind it is strengthened. Finally， an injection scheme which can induce a better thrust and thermal environment performance is proposed， and the equivalence ratio of K1~K4 is 0.6， 0.1， 0.1， 0.2， respectively.