Both experimental and numerical studies were presented on the flow field characteristics in the process of gaseous jet impinging on liquid–water column. The effects of the impinging process on the working performance...Both experimental and numerical studies were presented on the flow field characteristics in the process of gaseous jet impinging on liquid–water column. The effects of the impinging process on the working performance of rocket engine were also analyzed. The experimental results showed that the liquid–water had better flame and smoke dissipation effect in the process of gaseous jet impinging on liquid–water column. However, the interaction between the gaseous jet and the liquid–water column resulted in two pressure oscillations with large amplitude appearing in the combustion chamber of the rocket engine with instantaneous pressure increased by 17.73% and 17.93%, respectively. To analyze the phenomena, a new computational method was proposed by coupling the governing equations of the MIXTURE model with the phase change equations of water and the combustion equation of propellant. Numerical simulations were carried out on the generation of gas, the accelerate gas flow, and the mutual interaction between gaseous jet and liquid–water column.Numerical simulations showed that a cavity would be formed in the liquid–water column when gaseous jet impinged on the liquid–water column. The development speed of the cavity increased obviously after each pressure oscillation. In the initial stage of impingement, the gaseous jet was blocked due to the inertia effect of high-density water, and a large amount of gas gathered in the area between the nozzle throat and the gas–liquid interface. The shock wave was formed in the nozzle expansion section. Under the dual action of the reverse pressure wave and the continuously ejected high-temperature gas upstream, the shock wave moved repeatedly in the nozzle expansion section, which led to the flow of gas in the combustion chamber being blocked, released, re-blocked, and re-released. This was also the main reason for the pressure oscillations in the combustion chamber.展开更多
水电站过渡过程计算中水轮机尾水管进口最小压强须控制在-8 m H2O以上,以防止危险的水柱分离。对于水泵水轮机,压力脉动大且成份复杂,确定此最小压强时应该计入哪些压力脉动尚无明确答案。针对某直锥尾水管水泵水轮机模型,在转轮进口施...水电站过渡过程计算中水轮机尾水管进口最小压强须控制在-8 m H2O以上,以防止危险的水柱分离。对于水泵水轮机,压力脉动大且成份复杂,确定此最小压强时应该计入哪些压力脉动尚无明确答案。针对某直锥尾水管水泵水轮机模型,在转轮进口施加不同脉动流速,分析尾水管进口空化腔生成发展规律。发现尾水管最大空化腔体积与进口脉动流速频率相关;随频率增大,空腔体积有先快速增大后缓慢减小变化趋势;空化腔变化周期受压力脉动频率和尾水管出口压强波动共同影响。在实际转轮进口可能的压力脉动频率对尾水管空化腔波动都有较大影响,但频率与尾水涡频率一致时会有共振效应。尾水管水锤波动是产生空腔涡的根本因素。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51305204)
文摘Both experimental and numerical studies were presented on the flow field characteristics in the process of gaseous jet impinging on liquid–water column. The effects of the impinging process on the working performance of rocket engine were also analyzed. The experimental results showed that the liquid–water had better flame and smoke dissipation effect in the process of gaseous jet impinging on liquid–water column. However, the interaction between the gaseous jet and the liquid–water column resulted in two pressure oscillations with large amplitude appearing in the combustion chamber of the rocket engine with instantaneous pressure increased by 17.73% and 17.93%, respectively. To analyze the phenomena, a new computational method was proposed by coupling the governing equations of the MIXTURE model with the phase change equations of water and the combustion equation of propellant. Numerical simulations were carried out on the generation of gas, the accelerate gas flow, and the mutual interaction between gaseous jet and liquid–water column.Numerical simulations showed that a cavity would be formed in the liquid–water column when gaseous jet impinged on the liquid–water column. The development speed of the cavity increased obviously after each pressure oscillation. In the initial stage of impingement, the gaseous jet was blocked due to the inertia effect of high-density water, and a large amount of gas gathered in the area between the nozzle throat and the gas–liquid interface. The shock wave was formed in the nozzle expansion section. Under the dual action of the reverse pressure wave and the continuously ejected high-temperature gas upstream, the shock wave moved repeatedly in the nozzle expansion section, which led to the flow of gas in the combustion chamber being blocked, released, re-blocked, and re-released. This was also the main reason for the pressure oscillations in the combustion chamber.
文摘水电站过渡过程计算中水轮机尾水管进口最小压强须控制在-8 m H2O以上,以防止危险的水柱分离。对于水泵水轮机,压力脉动大且成份复杂,确定此最小压强时应该计入哪些压力脉动尚无明确答案。针对某直锥尾水管水泵水轮机模型,在转轮进口施加不同脉动流速,分析尾水管进口空化腔生成发展规律。发现尾水管最大空化腔体积与进口脉动流速频率相关;随频率增大,空腔体积有先快速增大后缓慢减小变化趋势;空化腔变化周期受压力脉动频率和尾水管出口压强波动共同影响。在实际转轮进口可能的压力脉动频率对尾水管空化腔波动都有较大影响,但频率与尾水涡频率一致时会有共振效应。尾水管水锤波动是产生空腔涡的根本因素。
