吸气式旋转爆震发动机热力循环过程分析与性能计算

Thermodynamic Cycle Analysis and Performance Calculation of Air-Breathing Rotating Detonation Engine

关键词:  吸气式  旋转爆震发动机  热力循环  性能模型  特征线方法

Key words:  Air-breathing mode  Rotating detonation engine  Thermodynamic cycle  Performance model  Method of characteristics

摘要:

为了快捷有效地指导发动机设计，有必要建立快速准确地获取吸气式旋转爆震发动机性能参数的计算方法。以飞行条件、发动机关键几何参数以及进气道和喷管的特性参数作为输入参数，通过将隔离段内复杂运动激波简化为正激波实现旋转爆震燃烧室与上游隔离段的压力匹配，应用二维特征线方法对燃烧室内复杂流动进行快速准确模拟，建立了吸气式旋转爆震发动机热力循环过程分析模型，计算得到发动机关键截面流动参数和发动机性能参数。以氢气和乙烯为燃料研究了进气道压缩温升、进气道喉道与燃烧室面积比以及余气系数对发动机性能的影响。结果表明：在一定的条件下进气道压缩温升和进气道喉道与燃烧室面积比的增加有利于发动机比冲性能的提升，但面积比的增加将导致发动机工作马赫数范围变窄，以氢气为燃料，余气系数为1，当面积比从0.3增至0.5，发动机工作马赫数范围由2.5~5收窄至3.5~5，而Ma=5状态最大比冲提升7%；在一定范围内余气系数增加有利于发动机比冲性能的提升，但将导致单位推力降低，以氢气为燃料，面积比为0.4，余气系数由1增至1.67，在Ma=3，4和5状态点，最大比冲性能分别提升25.4%，23.5%和20.3%，但最大单位推力分别降低24.7%，25.9%和27.9%；以乙烯作为燃料，发动机比冲和单位推力随进气道压缩温升的变化趋势与氢气一致，但性能偏低。研究提出的热力循环模型和计算方法实现了吸气式旋转爆震发动机性能的快速计算。

Abstract:

In order to guide the design of the air-breathing rotating detonation engine quickly and effectively， it is necessary to establish a calculation method to obtain the engine performance parameters fast and accurately. The flight conditions， the key geometric parameters of the engine and the characteristics of inlet and nozzle are used as the input parameters， the pressure matching between the rotating detonation combustor and upstream isolator is realized by simplifying the complex propagating shock wave in the isolator to a normal shock， and the complex flow in the rotating detonation combustor is calculated quickly and accurately by 2D characteristics method. An analytical model for thermodynamic cycle of the air-breathing rotating detonation engine is established. The flow parameters of the key sections and the engine performance parameters were calculated. Hydrogen and ethylene were chosen as the fuel to analyze how the temperature rise of the inlet throat by compressing， the area ratio of the inlet throat to the combustor and the excess air coefficient influenced the engine performance. The results show the increase of the temperature rise of the inlet throat and the area ratio of the inlet throat to the combustor is beneficial to the improvement of the specific impulse under certain conditions， however， the increase of the area ratio narrows the working Mach range.For the fuel of hydrogen the excess air coefficient is 1， when the area ratio increases from 0.3 to 0.5， the working Mach number range narrows from 2.5~5 to 3.5~5， however， the optimal specific impulse at Mach number 5 increases by 7%. The increase of the excess air coefficient is beneficial to the improvement of the specific impulse in a certain range， but leads to the decrease of the specific thrust， for the fuel of hydrogen the area ratio is 0.4， when the excess air coefficient increases from 1 to 1.67， the optimal specific impulses at Mach number 3， 4 and 5 increase by 25.4%，23.5% and 20.3% ，respectively， however， the maximum specific thrusts decrease by 24.7%，25.9% and 27.9%， respectively. For the fuel of ethylene， the change trend of the specific impulse and thrust with the increase of the temperature rise of the inlet throat is consistent with hydrogen， but the engine performance is lower. The thermodynamic cycle model and calculation method of this paper can calculate the performance of the air-breathing rotating detonation engine quickly.