低温流体汽蚀的数值计算及可视化实验研究

Numerical Simulation and Visualized Experimental Study on Cavitating of Cryogenic Fluids

关键词:  低温汽蚀  热效应  可视化实验  数值计算  汽蚀长度

Key words:  Cryogenic cavitation  Thermodynamic effects  Visualization experiments  Numerical simulation  Cavitation length

摘要:

为研究热效应对低温流体汽蚀的影响，选取文氏管为研究对象，进行数值计算及可视化实验研究。低温汽蚀计算模型考虑能量守恒的影响，物性参数随温度变化。使用高速摄影拍摄汽蚀发生位置及汽蚀区大小。热效应对常温水汽蚀的抑制很小为1.14%。液氮考虑热效应计算与实验结果误差为2.64%，吻合较好。由于低温流体的热物性，汽蚀发生伴有显著的温降及压降，汽蚀过程减弱，汽蚀区减小，最大体积分数下降20%，热效应对低温汽蚀的抑制作用明显。低温汽蚀受动量和能量交换的共同作用，液相、气相相互拖拽能力增强，汽蚀核心区由壁面扩展到整个流道；汽蚀区和气液界面的气泡浓度变化梯度更加平缓，气液界面不清晰。

Abstract:

To analyze the effect of the thermodynamic effects of cryogenic fluids cavitation， the venturi was selected as the research object， and the numerical simulation and visualized experimental research were conducted as well. Numerical model of the cryogenic cavitation considering the influence of energy conservation and physical properties were set to be updated with temperature. The location and size of cavitation were recorded by high speed photography. The inhibition of the thermodynamic effects on the room temperature water cavitation was 1.14%， which can be ignored. The error of liquid nitrogen considering thermodynamic effects calculation and experimental result was 2.64%， the calculation was in good agreement with the experimental result. Due to the thermal physical properties of the cryogenic fluids， cavitation is accompanied by significant temperature drop and pressure drop， cavitation process is weakened and cavitation zone decreases， maximum volume fraction decreased by 20%. The inhibition of thermodynamic effects on the cryogenic cavitation is obvious. Cryogenic cavitation is influenced by the effect of momentum and energy， and the interaction of the liquid phase and vapor phase is enhanced， the cavitation core region extending from wall to the whole passage. The bubble concentration gradient of cavitation zone and gas-liquid interface is gentler， gas-liquid interface is not clear.