环形燃烧室中凹腔对C_(2)H_(4)/Air旋转爆轰流场影响的数值模拟

Numerical Simulation of Cavity Influence on C_(2)H_(4)/Air Rotating Detonation Flow Field in Annular Combustor

为研究环形燃烧室中凹腔对旋转爆轰流场的影响,通过在开源计算流体动力学软件OpenFOAM框架内求解Navier-Stokes方程,对C_(2)H_(4)/Air旋转爆轰燃烧室(RDC)进行三维数值模拟研究。保持进气总压为0.6 MPa,分别在总温300 K、600 K和800 K条件下对比同轴圆环形和凹腔基环形两种构型RDC的主要流场特征,研究凹腔对旋转爆轰波传播特性的影响,定量分析不同热释放速率下消耗的燃料占比,对比了不同热释放速率下消耗的燃料比例。结果表明:对于凹腔基环形RDC,在凹腔内存在回流区,导致在凹腔上游流速缓慢,但在凹腔收缩段流动明显加速,RDC出口的面平均马赫数大于与之对应的同轴圆环形RDC;受燃料向RDC出口和凹腔内壁方向侧向膨胀的影响,相对于同轴圆环形RDC,爆轰波在凹腔基环形RDC中传播时具有更高的速度亏损;部分新鲜燃料与燃烧产物在凹腔内混合,提高了爆轰波波前反应物的温度;在相同进气条件下,同轴圆环形RDC以爆轰形式消耗的燃料占比更多。所得研究结果对RDC的结构设计和优化具有一定的指导意义。

The three-dimensional numerical simulation of C_(2)H_(4)/Air rotating detonation combustor(RDC)is carried out to study the influence of cavity on the rotating detonation flow field in annular combustor by solving Navier-Stokes equations in the framework of open source computational fluid dynamics software OpenFOAM.The main flow field features of annular and cavity-based annular RDCs are compared under the conditions of total inlet pressure of 0.6 MPa and total temperatures of 300 K,600 K and 800 K,the influence of cavity on the propagation characteristics of rotating detonation wave is studied,and the proportions of fuel consumed at different heat release rates are quantitatively analyzed.The results show that,for the cavity-based annular RDC,a recirculation zone exists in the cavity,which leads to a slow flow velocity in the upstream of the cavity,but the flow rate significantly accelerates in the contraction section of the cavity.The surface average Mach number at the outlet of RDC is larger than that of the corresponding annular RDC.Due to the lateral expansion of fuel towards the outlet of RDC and the inner wall of cavity,the detonation wave propagating in the cavity-based annular RDC has a higher velocity deficit than that in the annular RDC.Part of the fresh fuel is mixed with the combustion products in the cavity,which increases the temperature of reactant in front of detonation wave.The ratio of fuel consumption under different heat release rates was compared,which shows that the annular RDC consumes more fuel in the form of detonation than the cavity-based annular RDC under the same injection conditions.