孔板流量计孔型对流场影响的数值模拟

Numerical simulation influence on flow field of orifice flowmeter orifice shape

针对孔板流量计测量精度及节能降耗的要求,对5种结构的单孔板进行了数值模拟研究。进行了数值模拟与标准孔板实验比对,对模拟方法的可靠性进行了验证,在此基础上进一步完成了5种结构10组流速下的数值研究。通过速度矢量图得出孔口后流态的变化;计算流量系数,得出流量系数与雷诺数关系曲线、轴线距离与压力关系图、压差与雷诺数关系图。结果表明,5种孔板中外凹型孔板流量计Ⅱ因为板前缓冲段较为理想,对流体起到了整流的作用,减弱了板前流体死区的形成和板后涡流的形成,降低了孔板流量计的压力损失,且流量系数大,随雷诺数增大压差增大缓慢,压力恢复快。

In order to meet the requirements of measuring accuracy,energy saving and consumption reduction of orifice flowmeter,the numerical simulation of five kinds of orifice flowmeter is carried out.First,the numerical simulation is compared with the standard orifice plate experiment to verify the reliability of the simulation method.On this basis,the numerical study of 10 groups of flow rates with five kinds of structures was further completed.The change of flow state after the orifice is obtained by velocity vector diagram.The flow coefficient is calculated and the relationship curve between flow coefficient C and Reynolds number,the axis distance and pressure,pressure drop and Reynolds number diagram are obtained.The results show that five kinds of concave orifice plate flowmeter Ⅱ are ideal because the front buffer section of the orifice plate.It plays a rectifying role to the fluid,reduces the formation of dead zone in front of the plate and vortex formation behind the plate,and reduces the pressure loss of orifice flowmeter.And the flow coefficient is large,the pressure difference increases slowly with the increase of Reynolds number,the pressure recovery is fast.