不同压力差下微通道尺寸和表面粗糙度对摩擦系数的影响

该文数值模拟液体在圆形和梯形截面微通道内的流动,分析了层流和湍流下液体在微圆管内的流动状态。着重研究不同压力差、微通道尺寸和表面粗糙度下,液体在微通道内的流动摩擦系数,并通过摩擦系数随雷诺数的变化曲线推断微通道流动转捩的雷诺数范围。研究表明:微通道中流动的摩擦系数随雷诺数的增大逐渐减小;通道截面的当量直径会改变过渡状态存在的雷诺数范围;粗糙度会影响湍流状态下流动的摩擦系数,相同雷诺数下,粗糙度越大,摩擦系数越大。

INFLUENCES OF SIZE AND ROUGHNESS OF MICROCHANNELS ON FRICTION FACTORS UNDER DIFFERENT PRESSURES

The characteristics of liquid flow in the microchannels with circular and trapezoidal cross-sections were studied by numerical simulation.The friction factor of liquid flow in microchannels was investigated with different pressures,the sizes and roughness of microchannels.The different flow regimes of laminar and turbulence were also analyzed in the microtubes.In addition,the range of a transition Reynolds number can be inferred from the friction factor profiles under different Reynolds numbers.The friction factors in the microchannels decrease with the increasing of Reynolds numbers gradually.The Reynolds number at transition from laminar to turbulent flow changes with the cross-section’s equivalent diameter.At the same Reynolds number,the friction factor increases with the roughness of the inner wall of the microchannel when the flow is turbulent.