液氧甲烷变推力发动机螺旋槽再生冷却传热特性研究

Heat transfer characteristics of spiral channel regenerative cooling in LOX/LCH4 variable thrust engine

关键词:  液氧甲烷发动机  变推力  再生冷却  螺旋槽  传热特性

Key words:  Liquid oxygen methane engine  Variable thrust  Regenerative cooling  Spiral channel  Heat transfer characteristics

摘要:

为探究宽工况范围下螺旋槽再生冷却的传热特性，基于微小通道内低温工质的相变传热模型，采用一维传热计算方法，对5 kN级液氧甲烷变推力发动机开展了螺旋槽再生冷却传热特性研究。结果表明：本文所采用的传热计算模型可用于传热预估，与试验结果相比，冷却剂温升误差为4.3%，压降误差为1.1%，喉部处外壁温误差为-11%，在工程计算可接受范围内；相比于直槽，螺旋槽再生冷却能有效降低燃气侧壁温，同时，在宽范围变推力条件下，实际功率水平越低，冷却剂温升、压降越小，喉部燃气侧壁温越低，但“传热恶化区”内的壁温最大值反而越高，当发动机推力由额定工况的75%调整至20%时，燃气侧壁温的最大值由1 351 K增大至1 399 K；综合考虑壁面温度及冷却剂的压力损失，本文对冷却通道开展优化设计，对比四种冷却通道方案的传热性能，其中，方案4为最优方案，20% 额定功率水平工况时，冷却剂温升为491 K，压降为0.34 MPa，燃气侧壁温最大值也仅为1 297 K，较初始设计方案降低了102 K，远低于材料的极限温度。

Abstract:

In order to explore the heat transfer characteristics of spiral channel regenerative cooling under a wide range of working conditions， based on the phase change heat transfer model of cryogenic working medium in a tiny channel， this paper adopted one-dimensional heat transfer calculation method to study the heat transfer characteristics of spiral channel regenerative cooling for 5 kN liquid oxygen-methane variable thrust engine. The results show that the heat transfer calculation model adopted in this paper can be used for heat transfer prediction. Compared with the test results， the error of coolant temperature rise is 4.3%， the error of pressure drop is 1.1%， and the error of throat outer wall temperature is -11%， which is within the acceptable range of engineering calculation. Compared with the straight channel， the spiral channel regenerative cooling can effectively reduce the gas side wall temperature. Meanwhile， under a wide range of variable thrust conditions， the lower the actual power level， the smaller the coolant temperature rise and pressure drop， and the lower the throat gas side wall temperature， but the higher the maximum wall temperature in the “heat transfer deterioration zone”. When the engine thrust is adjusted from 75% to 20% of the rated power level， the maximum gas side wall temperature increases from 1 351 K to 1 399 K. Considering wall temperature and pressure loss of coolant comprehensively， this paper carried out optimization design of the cooling channel， and compared the heat transfer performances of four cooling channel schemes， among which， scheme 4 was the best. At 20% rated power level condition， the temperature rise of coolant is 491 K， the pressure drop is 0.34 MPa， and the maximum gas side wall temperature is only 1 297 K， which is 102 K lower than that of the initial design scheme and far lower than the ultimate temperature of materials.