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针对水下高速航行器用镁基水反应金属燃料冲压发动机,设定了3种质量组分配比的燃料,结合热力计算和二维轴对称数值模拟研究其工作特性。其中,两进水口处观测到的漩涡预言了在燃料燃烧过程中引发热声振荡的可能性。在3种燃料发动机各自的有效水燃比范围内,通过数值模拟可知两次水燃比的分配直接影响发动机内的燃烧稳定性;总水燃比的增加会引发一个最大的比冲值,同时热效率和推进效率分别单调增加和降低。另外,数值模拟和热力计算结果均显示燃料中镁含量的增加有益于发动机比冲及热效率的增加。本研究中燃烧特性、比冲及效率等工作特性随发动机工况的变化规律特征,可指导发动机整体结构构型及总体性能优化的方向,同时可对发动机内潜在的热声振荡特性进行预估以便设计相应的抑制策略。
Aiming at the magnesium-based water-reactive metal-fuel ramjet used in underwater high-speed craft, three types of fuels with mass ratio were set up, and their working characteristics were studied with thermodynamic calculation and two-dimensional axisymmetric numerical simulation. Among them, the eddy observed at the two intakes predicts the possibility of thermoacoustic oscillations during fuel combustion. Numerical simulation shows that the distribution of the two water-fuel ratios directly affects the combustion stability in the engine. The increase of the total water-fuel ratio will lead to a maximum specific value, and the thermal efficiency and propulsion Efficiency increases monotonically and decreases respectively. In addition, the results of numerical simulation and thermodynamic calculation show that the increase of magnesium content in the fuel is beneficial to the engine specific impulse and the increase of thermal efficiency. In this study, the characteristics of combustion, specific impulse and efficiency with the characteristics of engine operating conditions change law, can guide the overall structure of the engine configuration and overall performance optimization direction, while the potential engine thermoacoustic oscillation characteristics of the estimated In order to design the appropriate suppression strategy.