内管自转且公转时环管幂律流的受力分析

Force analysis of power-law fluid annular flow with the inner pipe in rotation and in orbital motion

数值模拟了环管中内管偏心自转且公转时由轴向压力所驱动的幂律流体充分发展层流,分析了内管上的流体作用力。结果表明,内管偏心自转时流体作用力具有推动内管作和自转同向公转的效果。当只有外力矩驱动内管自转时,由于流体的作用,随内管线密度的不同,内管能达到的受力平衡态也不同:线密度较小时内管仅能在同心自转时达到受力平衡;线密度较大时内管能在作具有不变角速度和偏心率公转时达到受力平衡,且内管线密度越大,对应的受力平衡的公转的偏心率也越大。

The fully developed laminar flow confined in an annulus was simulated numerically, when the inner pipe is rotating eccentrically with an orbital motion, and the flow is driven by axial pressure, and the fluid is in power-law type. The flow-induced forces on the inner pipe were analyzed. The results show that when the inner pipe is rotating eccentrically, the flow-induced forces on the inner pipe always have the effect of pushing the inner pipe to move along the same direction as its rotation. The inner pipe may have different motion states with force equilibrium depending on its linear density, when only a torque is imposed externally to drive its rotation： when the linear density is small enough,only in the concentric rotating situation can the inner pipe get force balance; when the linear density is large enough, the inner pipe can get force balance while rotating with orbital motion,and the orbital motion has constant eccentricity and speed. The greater the linear density is,the larger the eccentricity of the orbital motion is.