基于乙烯/空气详细反应机理的旋转爆轰过程数值模拟

为了研究乙烯/空气的旋转爆轰传播特性,采用OpenFOAM7中rhoReactingCentralFoam求解器,以及乙烯/空气21组分36步基元化学反应模型,对旋转爆轰传播过程进行了二维数值模拟研究。通过改变预混气各组分的质量分数,验证了基元反应在旋转爆轰的可适用性,研究了当量比对旋转爆轰波的影响,分析了旋转爆轰燃烧室的流场结构、压力增益和燃料比冲。研究结果表明:在当量比0.7～1.1范围内旋转爆轰波能够自持传播,其传播模态均为单波; 在来流总压0.6 MPa和总温300 K时,压力增益均保持在30%以上,且随当量比的增加旋转爆轰波传播速度、阻塞比、压力增益以及燃料比冲均增大,速度亏损逐渐减小,但随着当量比的增加其增长速率和降低速率呈下降趋势; 爆轰波稳定传播时,中间产物OH集中在爆轰波后方和斜激波下游,反映了化学反应阵面的形状。爆轰波传播过程中,由于爆轰波扫过后压力过高,新鲜燃料无法供应,导致温度曲线图出现波动。

Numerical Simulation of Rotating Detonation Process Based onDetailed Ethylene/Air Reaction Mechanism

To study the propagation characteristics of ethylene/air rotating detonation,the two-dimensional numerical process of the rotating detonation propagation was established solving by the rhoReactingCentralFoam in OpenFOAM7 using ethylene/air 21-species and 36-step reaction kinetics model. The applicability of the elementary reaction in the rotating detonation was validated by changing the fuel and air mass fraction,and the effect of the equivalence ratio on the rotating detonation wave was studied,and the flow field structure,the pressure gain and the fuel specific impulse of the rotating detonation combustion chamber were analyzed. The results show that rotating detonation wave can propagate sustainably in single-wave under the equivalence ratio ranging from 0.7-1.1. For an inlet total pressure of 0.6 MPa and an inlet total temperature of 300 K,the pressure gain remains above 30%. With the equivalence ratio increasing,the propagation velocity,the block ratio,the pressure gain and the fuel specific impulse of rotating detonation wave increase,while the velocity deficit gradually decreases. Besides,with the increase of the equivalence ratio,the increasing rate and decreasing rate show a downward trend. Intermediate product OH mainly distributes behind detonation wave and downstream of oblique shock wave while detonation wave propagating stably,which reflects the shape of chemical reaction front. During the propagation of the detonation wave,the fresh fuel and oxidant mixture cannot inject into combustion chamber due to the high pressure after the detonation wave,which results in fluctuations of the detonation temperature.