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针对恒压差变化率下矩形通道内的流态转捩特性进行理论和实验研究。通过理论研究,得到恒压差变化率下的层流速度分布。以层流速度分布为基础,应用能量梯度法,对加速和减速情况下的转捩雷诺数(Re)进行计算,并分析影响转捩Re的因素。分析结果表明:加速过程中转捩Re低于稳态情况下的转捩Re和减速过程中的转捩Re高于稳态情况下的转捩Re;初始稳态压差越接近稳态转捩时的压差,转捩Re偏离稳态转捩Re就越小;压差变化率对转捩Re几乎没有影响。通过加减速实验研究得到的转捩Re变化规律和理论结果基本一致,但在压差变化率影响方面存在差异。
Theoretical and experimental studies on the characteristics of the flow regime in a rectangular channel under constant rate of pressure difference change were carried out. Through theoretical research, we get the velocity distribution of laminar flow under constant pressure difference. Based on the laminar flow velocity distribution, Reynolds number (Re) was calculated by energy gradient method under accelerating and decelerating conditions, and the factors influencing the Reynolds number were analyzed. The results show that during the acceleration process, the transition Re is lower than that under steady state and the transition Re at deceleration is higher than that under steady state; when the initial steady-state pressure is closer to steady state transition Of the pressure difference, the transition 捩 Re deviates from the steady-state transition 捩 Re the smaller; pressure changes in the rate of change 捩 Re almost no effect. The law of change of Re 捩 Re obtained from the experiment of acceleration and deceleration is basically consistent with the theoretical result, but there is a difference in the influence of the rate of change of pressure difference.