关键词: 压力场 初始加速度 轴速分量 孔口流量计

Abstract:

In order to understand the dynamic characteristics of office, we study the transient flow through a pipe orifice by numerical analysis. The effect of   pressure differences on the initial acceleration of flow, the mean axial velocity component ωw, the flow rate q, the distance of reattachment point z a and so on have been discussed. The relative curves of ωw, q, z with respect to t under variable variable pressures are shown. The small variation of th   he flow rate also accompanies the variation of the pressure field; therefore a special attention should be paid to the precise measurements of unsteady  flow using the orifice meter.

Key words: （pressure field;initial acceleration, axial velocity component, orifice meter）