C2H4/CH4/H2混合气旋转爆轰波传播特性数值模拟研究

Numerical Simulation of Rotating Detonation Wave Propagation Characteristics of C2H4 /CH4 /H2 Mixture

关键词:  旋转爆轰  多组分气体  进气压力  当量比  模态转变机理

Key words:  Rotating detonation  Multi-component gas  Inlet pressure  Equivalence ratio  Modal transformation mechanism

摘要:

为了研究煤油裂解气旋转爆轰的传播特性，以C₂H₄/CH₄/H₂混合气为替代燃料，空气为氧化剂，利用基于OpenFOAM的计算程序rhoReactingCentralFoam开展了该混合气的二维旋转爆轰过程数值模拟研究。研究了进气压力、当量比和混合气组分比例对旋转爆轰波传播特性的影响，探究了旋转爆轰波在传播过程中模态转变的机理。结果表明：在不同计算条件下旋转爆轰波呈现四种传播模态：单波模态、双波对撞模态、单/双波混合模态以及三波模态。双波对撞时，爆轰波稳定传播，爆轰波波头高度保持一致；在三波模态中，旋转爆轰波的传播方向发生改变。爆轰波模态转变的本质是增大进气压力和当量比后，在爆轰产物与新鲜预混可燃气的接触面上形成利于发生化学反应的环境条件，接触面上发生爆燃产生新的激波，高温高压的激波与新鲜预混可燃气碰撞，进一步提高化学反应速率，获得足够的能量逐渐增强为爆轰波，促进了爆燃转爆轰过程。

Abstract:

In order to study the propagation characteristics of rotating detonation of kerosene cracked gas， using C₂H₄/CH₄/H₂ mixture as alternative fuel and air as oxidant， a numerical simulation study of the two-dimensional rotating detonation process of the mixture was carried out using a calculation program rhoReactingCentralFoam based on OpenFOAM. The effects of the total inlet pressure， the equivalent ratio and fuel mixing ratio on the propagation characteristics of the rotating detonation wave and the mechanism of the mode transition of the rotating detonation wave during the propagation process are studied. The results show that the detonation wave presents four propagation modes under different calculation conditions： single-wave mode， double-wave collision mode， single/double-wave mixed mode， and three-wave mode. When double waves collide， the detonation wave propagates steadily， and the height of the detonation wave head remains the same. In the three-wave mode， the propagation direction of the rotating detonation wave changes. The essence of the mode transformation of detonation wave is that after increasing the inlet pressure and equivalent ratio， the environmental conditions conducive to chemical reaction are formed on the interface between detonation products and fresh premixed combustible gas， and a new shock wave occurs on the contact surface. High temperature and high pressure shock wave collides with fresh premixed combustible gas， which further increases the chemical reaction rate， and the shock wave obtains enough energy to gradually enhance to detonation wave， which promotes the process of deflagration to detonation.