摇摆运动下窄矩形通道单相瞬变流动时均阻力特性研究

Study on Time-Average Friction Characteristics of Low Flow Rate Single-Phase Flow in a Rectangular Channel in Rolling Motion

对摇摆运动下窄矩形通道低流速单相瞬变流动时均阻力特性进行实验研究。实验工质为去离子水,窄矩形通道当量直径为5.39 mm,雷诺数范围为800～20000,瞬变流动流量相对波动幅度超过30%。通过2种方法计算得到摇摆运动条件下流动时均阻力系数。分析结果表明:使用不同的方法计算得出的时均阻力系数在层流区的变化规律不同,不同的方法表征不同的物理意义。若先根据达西公式求瞬时阻力系数再对其求时均值,该时均值表征时均粘性耗散;而采用先求压差、流速均值后再根据达西公式计算阻力系数时,该阻力系数表征时均摩擦阻力压降。

Studies of time-average friction characteristics of low flow rate single-phase flow in a rectangular channel under rolling motion condition were carried out.The test fluid is deionized water and the equivalent diameter of the rectangular channel is 5.39 mm,the range of the Reynolds number is 800-20000 and the amplitude of the flow rate exceeds ±30%.Two methods were employed to calculate the time-average friction coefficient and the results showed that the time-average friction coefficients obtained by the two methods are different in laminar flow.Different methods represent different physical meanings.When the time-average friction coefficient is calculated by integrating the instantaneous friction coefficient which is acquired by Darcy equation in a period,this time-average value represents time-average viscous dissipation.On the other hand,when the time-average coefficient is computed by Darcy equation which employs time-average pressure drop and velocity,this time-average friction coefficient represents time-average pressure drop.