煤油-空气预混气流超声速燃烧数值研究

Numerical study on supersonic combustion of kerosene-air premixed flow

关键词:  煤油  超音速燃烧  高温气体  引导火焰+  数值仿真

Key words:  Kerosene  Supersonic combustion  High temperature gas  Pilot flame~+  Numerical simulation

摘要:

对以高温燃气作为引导火焰的煤油 空气预混气流超声速燃烧进行了数值模拟,系统研究了预混气流的温度、压力、当量比,以及预混气流与高温燃气的压力匹配关系等多种重要因素对超声速燃烧的影响。结果表明:随着预混气流静温、静压的升高,着火点诱导的压缩波增强,最高燃烧温度升高,火焰传播角相应增大;预混气流的当量比为化学恰当比时,燃烧温度最高;与静压匹配的情况相比,静压不匹配情况下的火焰传播角增大,当预混气流的静压高于高温燃气的静压时,着火点前移,反之,着火点则后移;此外,在多种情况下,燃烧室下壁面边界层都出现了自燃现象。

Abstract:

A numerical study was conducted for the supersonic combustion of premixed kerosene-air flow ignited by a high-temperature hot gas as the pilot flame. Many factors, which have important influences on supersonic combustion, were systematically explored. These factors include the temperature, pressure, equivalence ratio of the supersonic premixed flow, and the pressure matching relations between the premixed flow and the hot gas. The results show that with the rise of the static temperature or the static pressure of the premixed flow, the compression wave induced by ignition intensifies, resulting in an increased highest temperature and an expanded flame-spreading angle. When the equivalence ratio of the premixed flow is exactly stoichiometric, the combustion temperature reaches the highest. When the static pressure of the premixed flow is higher than that of the hot gas, the ignition distance is shorten, compared with the static pressures matched cases. On the contrary, when the latter is higher than the former, the ignition distance is prolonged. Moreover, the flame-spreading angle is larger in the non-matched cases than that of the matched case. Besides, auto-ignition occurs in the boundary layer at the lower wall in many cases.