火箭推进

气体吹除乳化技术可以大幅提高燃料流经燃气发生器时产生的压降,从而满足变工况下燃料的雾化及燃烧需求。目前气体吹除后燃气发生器内压降变化的定量规律还不清晰,为此,采用数值模拟的方法,对某型号燃气发生器全域及局部喷嘴进行了变工况计算,得到了氮气吹除过程中燃气发生器内煤油的相、速度以及压力分布规律,并针对喷嘴处的单相流及多相流压降特性进行拟合分析。结果显示:不同喷嘴处的煤油相分布具有不均匀性,喷嘴间流量差距可达66%; 使用氮气吹除后的喷嘴处压降相较于煤油单相流可提升1.64倍以上,且喷嘴处的气体单相流压降特性系数随背压呈现线性变化规律,而煤油单相流阻力系数则与流量呈现幂函数规律; 基于马尔基涅利公式提出了燃气发生器喷嘴处压降特性的集总参数模型,与数值计算结果及实验结果的平均误差为3.93%,具有较好的预测性。

The gas and emulsification technology can significantly increase the pressure drop when the fuel flows through the gas generator, so the atomization and combustion requirements of the fuel can be satisfied under variable working conditions. However, there is still a lack of quantitative research on the changing law of pressure drop in the process. In this paper, the CFD(Computational Fluid Dynamics)method was used to calculate the whole field and local nozzles of a certain type of gas generator under variable working conditions, the phase, velocity and pressure distribution laws of kerosene in the gas generator during the nitrogen blowing process were obtained. The flow and multiphase flow pressure drop characteristics were fitted and analyzed. The results show that the distribution of kerosene phase at different nozzles is not uniform, and the flow rate difference between nozzles can be up to 66%; the pressure drop at the nozzles after nitrogen blowing can be improved by more than 1.64 times compared with the single-phase flow of kerosene; the pressure drop resistance coefficient of the gas single-phase flow at the nozzle shows a linear change with the back pressure, while the kerosene single-phase flow pressure drop resistance coefficient shows an exponential law with the flow rate. The mathematical model of the pressure drop characteristics at the gas generator nozzle based on the Marchinelli formula has an average error of 3.93% with the numerical calculation results, which has good predictability.

引言
1 计算模型
2 气体吹除乳化过程物理场分布
3 喷嘴结构压降特性
4 马尔基涅利公式拟合
5 结论

图1 气体吹除乳化过程<br/>Fig.1 Emulsification process

图1 气体吹除乳化过程
Fig.1 Emulsification process

图2 燃气发生器结构<br/>Fig.2 Structure of a gas generator

图2 燃气发生器结构
Fig.2 Structure of a gas generator

图3 网格无关性验证<br/>Fig.3 Irrelevance verification

图3 网格无关性验证
Fig.3 Irrelevance verification

图4 燃气发生器喷嘴处压力分布<br/>Fig.4 Pressure distribution of nozzles in gas generator nozzle

图4 燃气发生器喷嘴处压力分布
Fig.4 Pressure distribution of nozzles in gas generator nozzle

图5 燃气发生器喷嘴内流线图<br/>Fig.5 Local stream line in gas generator nozzle

图5 燃气发生器喷嘴内流线图
Fig.5 Local stream line in gas generator nozzle

图6 燃气发生器内煤油相分布<br/>Fig.6 Phase distribution of gas generator injector

图6 燃气发生器内煤油相分布
Fig.6 Phase distribution of gas generator injector

图7 混合腔不同截面处的煤油相分布<br/>Fig.7 Kerosene distribution of mix chamber

图7 混合腔不同截面处的煤油相分布
Fig.7 Kerosene distribution of mix chamber

图8 不同喷嘴处的煤油出流流量<br/>Fig.8 Kerosene flow distribution of circumference

图8 不同喷嘴处的煤油出流流量
Fig.8 Kerosene flow distribution of circumference

表1 计算工况
Tab.1 Calculation condition

图9 氮气单相流压降特性<br/>Fig.9 Pressure drop characteristics with nitrogen flow

图9 氮气单相流压降特性
Fig.9 Pressure drop characteristics with nitrogen flow

图10 煤油单相流压降特性<br/>Fig.10 Pressure drop characteristics with kerosene flow

图10 煤油单相流压降特性
Fig.10 Pressure drop characteristics with kerosene flow

图11 背压4 MPa时两相流压降特性<br/>Fig.11 Pressure drop characteristics at 4 MPa back pressure

图11 背压4 MPa时两相流压降特性
Fig.11 Pressure drop characteristics at 4 MPa back pressure

图12 背压8 MPa时两相流压降特性<br/>Fig.12 Pressure drop characteristics at 8 MPa back pressure

图12 背压8 MPa时两相流压降特性
Fig.12 Pressure drop characteristics at 8 MPa back pressure

图13 n值分布特性<br/>Fig.13 n at different condition

图13 n值分布特性
Fig.13 n at different condition

图14 仿真值和模型预测值对比<br/>Fig.14 Numerical comparison between calculation and prediction

图14 仿真值和模型预测值对比
Fig.14 Numerical comparison between calculation and prediction

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备注

引言

1 计算模型

2 气体吹除乳化过程物理场分布

3 喷嘴结构压降特性

4 马尔基涅利公式拟合

5 结论

期刊信息