低温节流过程实验装置研制及初步实验验证

Development and Preliminary Experimental Verification of Apparatus for Cryogenic Throttling Process

为了深入理解航天低温推进剂在热力排气系统中的节流特性,本文推导了过冷低温液体节流后气相质量分数与入口液体过冷度之间的热力学关系,设计并搭建了一套用于研究低温流体节流前后气液两相流状态特性的实验装置。以液氮为研究对象,测量了过冷液氮节流前后压力、温度等状态参数以及质量流量。研究结果表明,气相质量分数和节流后空化区最大温降之间,空化数和压比之间均存在近似线性关系;在节流前压力一定的情况下,节流后的气相质量分数随着过冷度的增大逐渐减小,也近似呈线性关系,实验所得斜率与理论值误差1.3%,验证了热力学关系的正确性,实验装置功能满足设计目的和测试要求。

To better understand the throttling behavior of cryogenic propellants in the thermodynamic vent system of the tank,thermodynamic relations between the mass fraction of gas phase after throttling and the subcooling degree of the inlet liquid is deduced;and an apparatus is designed and built to study the state characteristics of the gas-liquid two-phase flow before and after throttling of cryogenic fluids.Taking liquid nitrogen as the flowing substance,state properties such as pressure,temperature,and mass flow before and after throttling are measured.The results show that there is an approximately linear relationship between the mass fraction of gas phase and the maximum temperature drop in the cavitation region after throttling.The cavitation number is also approximately linearly proportional to the pressure ratio.Under the condition with the constant pressure before throttling,the mass fraction of the gas phase after throttling decreases linearly with the increase of the subcooling degree.The deviation between experimental data and the theoretical prediction of the slope is within 1.3%,which verifies the thermodynamic relation.The function of the experimental apparatus meets the design purpose and test requirements.