超燃发动机燃烧模态判别准则初步研究

Preliminary Study on Criterion of Indentifying Combustion Mode for Scramjet

为建立超燃发动机燃烧模态定量判别准则,针对马赫数3.0,总温1500K,总压2.1MPa的来流,完成了燃烧模态的实验和数值模拟研究。对比分析了不同当量比条件下燃烧室马赫数分布和隔离段激波结构,确定了燃烧模态判别采用的两个压力测点特征位置,研究了燃油增加过程中特征位置壁面压强比值的动态特性。结果表明,随着当量比的增加,燃烧模态由超燃模态转变为亚燃模态,当量比0.6是超燃模态过渡到亚燃模态的转换点。特征位置压比变化率最大时刻的比值1.5可以作为定量判别燃烧模态的依据,当特征位置壁面压强比值小于1.5时为超燃模态,大于1.5时为亚燃模态。

In order to construct quantificational criterion of indentifying combustion mode for scramjet,experimental study and numerical simulation were carried out at the inflow Mach number 3.0,stagnation temperature1500 K,stagnation pressure 2.1MPa. Mach number distribution in combustor and shock wave structures in isolator were compared and analyzed for different equivalence ratio. Two characteristic locations,where the wall pressure ratio used to constitute criterion of indentifying combustion mode,have been confirmed. The transformation process of pressure ratio in characteristic location with the fuel increasing was researched. Results show that combustion mode changes from scramjet-mode to ramjet-mode with equivalence ratio increasing,and the transition occurred at the equivalence ratio 0.6. The maximun variation 1.5 of pressure ratio in characteristic location can be used as quantificational criterion of indentifying combustion model. The pressure ratio of scramjet-mode is less than 1.5,and the pressure ratio of ramjet-mode is greater than 1.5.