矩形通道内脉动湍流流动特性实验研究

Experimental Study on Flow Characteristics of Pulsating Turbulent Flow in Rectangular Channel

在流量脉动条件下,本文对矩形通道内的湍流流动特性进行了实验研究,通过理论分析,得到了影响脉动湍流的主要作用力和关键的无量纲数,分析了脉动周期、相对振幅等因素对流量与压降的相位差、压降-流量曲线、时均摩阻系数的影响,并与稳定流动状态下的流动特性进行了对比。实验结果表明:对于低频脉动湍流,压降驱动力、摩擦阻力和流体自身惯性力是影响流动特性的主要作用力;脉动湍流中,流量的变化滞后于压降变化,存在相位差;由于流体的惯性作用,脉动周期越小,流量脉动的幅值越小;速度相对振幅增大并超过临界值时,时均摩阻系数会显著增大。

Characteristics of pulsating turbulent flow in a rectangular channel w ere investigated experimentally. The dimensionless numbers for acting force in pulsating turbulent flow are obtained by theoretical analysis. The effects of pulsating period and relative amplitude on flow field in rectangular channel w ere analyzed. Characteristics of pulsating turbulent flow w ere compared w ith that of steady flow. The results show that pressure driving force,friction force and inertial force are the main acting forces affecting flow characteristics of low-frequency pulsating flow. Flow rate change lags behind the variation in pressure drop,a phase difference exists. When pulsating period becomes small,the pulsating amplitude of flow rate w ill decrease as the inertia of fluid. Besides,the period-averaged friction coefficient w ill increase rapidly w hen relative velocity amplitude exceeds the critical value.