Effect of Flow Characteristics in the Downstream of Butterfly Valve on the Flow Rate Measurement using Venturi Tube

摘要

For testing large-capacity pump, the accurate flow rate measurement is needed in the test loop. As a measuring method of flow rate, venturi tube is recommended due to its low pressure loss. However, upstream disturbance of loop component such as valve has an effect upon the accuracy of flow rate measurement. For controlling flow rate in case of high flow rate and large-scale piping system, butterfly-type valve is generally used due to its compactness. However, butterfly valve disturbs downstream flow by generating turbulence, cavities, or abrupt pressure change. In this study, the effect of downstream disturbance of butterfly valve on the flow rate measurement using venturi. tube is investigated. Test loop consists of circulation pump, reservoir, butterfly valve, venturi tube, and reference flow meter. The test is conducted with regard to a different valve opening angle of butterfly valve. NV system is used to visualize and analyze flow in the downstream region of butterfly valve. According to valve opening angle, the flow characteristics and the accuracy of flow rate measurement are investigated.