0.3 m低温风洞液氮供给系统研制

基于系统级的一维热流体模拟分析,建立了适用于研究分析0.3 m低温风洞液氮供给系统的数学模型,并开展了系统漏热、两相流及缓冲罐中液氮容积等流体动力学分析;在系统现有控制策略及试验数据的基础上,基于该数学模型开展了系统压力动态响应分析,获得了在阀门动态调节过程中管网压力的瞬态响应,计算结果与试验值的总体误差控制在10%以内。喷射压力一致化改造避免了阀间干扰,添加的回流管道消除了供给末端的两相流现象,使喷射压力控制精度达到1.1%,调节时间减少到23 s,实现了风洞总温快速安全调节和精确控制。

Development of liquid nitrogen supplying system of 0.3 m cryogenic wind tunnel

A numerical model was built to investigate the dynamic performance of the liquid nitrogen supplying system in the 0.3 m cryogenic wind tunnel. Based on one-dimensional thermal fluid analysis, the model was used to analyze heat leakage, level of the accumulator, two-phase flow and injection pressure. Combining the numerical model with control strategy and experiments, the dynamic pressure analysis for the injection rake was achieved. It showed that the relative error between numerical results and experimental data was below 10%. During experimental validation, the interference of the four regulating valves was avoided with universalization of the nominal working pressure of injection nozzles and convergence of pipes after these valves. The second recirculation pipe above the injection rake was used to eliminate the two-phase flow phenomenon of the terminal of the system, helping to make the control accuracy reach 1.1%, and adjust time to 23 s. With the numerical studies and reconstruction of the pipes and nozzles, the liquid nitrogen supplying system is able to meet the requirement of the total temperature control of the wind tunnel.