非稳态条件下平板通道内层流速度分布研究

Study on Unsteady Laminar Velocity Distribution in Plate Channel

针对平板通道内非稳定条件下层流的速度分布特点及阻力特性进行了理论和实验研究。基于非稳态条件下平板通道内的数学模型,分析了初始速度分布、压力梯度变化率、加(减)速时间对瞬时速度分布的影响。结果表明:非稳态层流的速度分布特点与通道尺寸、流体性质、压力梯度变化率和加速时间有关;相同截面平均流速条件下,加速情况下的中心流体速度小于稳态的,且加速流动使沿程流动损失增加,减速流动则恰好相反,实验验证结果与理论分析结果符合良好。

T he velocity distribution and resistance characteristics of unsteady laminar flow in plate channels were investigated theoretically and experimentally . Based on mathematical model of unsteady laminar flow , the influences of initial velocity distribution ,pressure gradient rate and duration of acceleration （deceleration ） on the instantaneous velocity distribution were analyzed .The results indicate that the velocity distribution of unsteady laminar flow is affected by channel size , fluid properties , pressure gradient rate and acceleration time . Under accelerated flow condition , the＆amp;nbsp;center fluid velocity is less than steady-state center fluid velocity , the flow resistance increases with the acceleration flow ,and the deceleration flow is on the contrary .The results of experimental verification show that experimental data agree well with the result of theoretical analysis .