通过对某电厂流量孔板进行数值研究,分析不同断面的流出系数及压力分布规律,得出如下结论取压孔应设置在上游最大压力和下游最小压力处,且下游取压孔应设置在距孔板中心距离(0.3～0.5)D范围内,上游取压孔应设置在距孔板中心距离(0.5～1.5)D范围;不同的取压孔距离严重影响流体质量流量的测量精度,所以流量孔板在安装时,严格按照取压孔尺寸安装,并根据取压孔的实际位置适当修正流出系数;典型断面的下游断面存在明显的回流现象,回流流量占管道质量流量的15%左右。分析结果可为电厂孔板差压测量安装、测试和调整提供参考。
关键词：
流量计; 孔板; CFX; 差压; 计算
Numerical research on the orifice-plate of a powerplant was carried out to analyse the discharge coefficient and pressure distribution at different sections. Results shows that the pressure measurement holes should be set at positions with the maximum pressure in the upstream and minimum pressure in the downstream. The downstream pressure measurement hole should be set at a distance 0.3D to 0.5D away from the plate center; while the upstream pressure measurement hole should be set at a distance 0.5D to 1.5D away from the plate center. Since the distance between the pressure measurement holes could seriously affect the measurement accuracy of flow rate, the installation of the orifice-plate flowmeter must be in strict accordance with the size of pressure hole, and the discharge coefficient should be corrected according to the actual position of measurement holes. There were obvious reflux at the downstream of the typical section, and the reflux flow rate accounted for 15% of the total flow rate. This research could provide reference for the pressure measurement, installation, test and adjustment of orifice-plate flowmeter.
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