微型涡喷发动机燃烧室优化设计

Optimization of a micro turbojet engine combustion chamber

由于供油方式和来流条件不同,现有微型涡喷发动机燃烧室直接参照大型航空发动机燃烧室设计,存在明显"尺度效应",导致微型涡喷发动机燃烧室性能较差,主要表现为燃烧室壁面温度过高、燃烧稳定性差和出口温度分布均匀性差。该文采用ANSYS和CFX数值模拟分析了现有某型号微型涡喷发动机燃烧室内的空气流动和燃烧过程,并通过冷态实验验证了数值模拟的有效性;提出"气涡裹液"设计理念,设计的燃烧室构型的数值仿真结果表明:出口温度分布系数从传统的0.54降低到0.15,所设计的燃烧室构型改善了燃烧室和涡轮的工作环境,提高了发动机的热效率和推力。

Micro turbojet engine combustor designs cannot be directly scaled from large aero-engine combustion chamber designs due to the different fuel supply modes and inflow conditions that affect the micro turbojet combustor efficiency. Bad designs lead to high wall temperatures, poor combustion stability and nonuniform outlet temperature distributions. Both ANSYS and CFX were used in this study to analyze the air flow and combustion characteristics in the combustion chamber of a micro turbojet engine. The numerical simulations were validated by comparisons with cold state tests. A "gas swirling liquid" design was then developed to improve the combustion. The numerical simulation results show that this design reduces the combustion chamber outlet temperature distribution coefficient from the traditional 0.54 to 0.15, which greatly improves the combustion chamber and turbine efficiencies and the thermal efficiency, and the thrust of the micro turbojet.