几何参数对矩形微通道内流体流动特性的影响

以试验手段对8根不同水力直径矩形微通道内蒸馏水的流动特性进行研究,测量得到了矩形微通道内流体流动时摩擦阻力系数f和摩擦常数P_o随Re数的变化规律,分析了矩形微通道水力直径、深宽比及长径比等几何参数对其内流体流动特性的影响规律和方式.结果表明:对于深宽比相同的微矩形通道,水力直径或长径比的减小都将引起内流体流动的f值和Po值的增大;而对于长径比相近而深宽比不同的矩形微通道而言,随着深宽比的减小,微通道内的f值和Po值也将增大;文中研究范围内,深宽比对矩形微通道内流体流动特性的影响更大;矩形微通道内流体流动的摩擦阻力系数是水力直径、深宽比及长径比等几何参数的复杂函数.

Influences of geometric parameters on flow characteristics of rectangular microchannels

The flow characteristics of eight rectangular microchannels with different geometric parameters are measured when distilled water is used as a working fluid. The relationship between friction factor or Poisuille number and Reynolds number is obtained, further the influences of hydraulic diameter, the ratio of height to width, and the ratio of channel length to hydraulic diameter on flow characteristics are analysed. The results show that the friction factor and Poisuille number increase with the decreasing hydraulic diameter and length-to-hydraulic diameter ratio at the same height-to-width ratio. For the microchannels with nearly the same length-to-hydraulic diameter ratio but different height-to-width ratio, the friction factor and Poisuille number grow with the reducing height-to-width ratio. Specially, in the range of variation of parameters interested in our study, the influence of height-to-width ratio is more denominated than the other geometric parameters. Hence the friction factor of rectangular microchannels is a complicated function of hydraulic diameter, height-to-width ratio and length-to-hydraulic diameter ratio.