长微直管内气体低速流动的亚堵塞现象

长微直管道内多流态并存的流动特性研究不仅有理论意义，而且在太空飞行器的控制系统中有着重要的应用价值.采用实验研究和理论模型近似分析相结合的方法研究了长微直管道内的气体流动特性.实验中，以空气为工作介质，进口压力分别设定为130，250，320kPa，出口压力变化范围为9—100?kPa.沿程分布有五个测压点，进出口设有温度传感器，测量出口流量的同时可以得到沿程压力分布.近似理论模型采用二维平板近似模型.研究发现，在保持进口压力不变、不断降低出口压力的条件下，当进出口压比低于5.3左右时，质量流量随压比增加 关键词： 长微直管道 亚堵塞 表面积与体积比 多流态并存 临界压比

Sub-choking phenomenon of low-speed gas flow in a long-constant-area microchannel

The study on gas flow characteristics in a long-constant-area microchannel in mixed Kn-regime flows has not only theoretical meaning, but also important application in controlling the system of outer space aerocrafts. Flow characteristics were studied based on experiments and approximate theoretical analysis. The inlet pressure was 130, 250 and 320?kPa, and the outlet pressure ranged from 9 to 100?kPa. Five pressure measuring points were distributed along the microchannel and the temperature sensors were located at the inlet and outlet. The pressure distribution and the volume flow rate of air were measured experimentally. An approximate theoretical model based on Poiseuille flow was adopted. Experimental investigations with the long-constant-area microchannel indicate that the mass flow rate through the microchannel changes little as the inlet-to-outlet pressure ratio reaches a certain critical value. The phenomenon is defined as sub-choking and the corresponding pressure ratio is defined as the sub-choking-critical-pressure-ratio. The phenomenon of sub-choking is due to the surface effects. Moreover, the effects of the ratio of surface to volume on the critical pressure ratio are studied.
Keywords： long-constant-area microchannel sub-choking surface-to-volume ratio multi-regime mixing critical pressure ratio