Effects of varying orifice diameter and Reynolds number on discharge coefficient and wall pressure

Abstract

In this paper, an experimental study has been performed to investigate the performance of varying diameter of orifice that made from acrylic plastic on the flow characteristics. A colour water has been used as a working fluid to flow through a PVC pipe system. The orifice has a sharp-edged with 30° angle and the pipe system has thirty tapping points across the orifice for the pressure measurement. The experiments have been carried out for different beta ratio and Reynolds number. The results clearly demonstrated that the beta ratio has a positive effects on the discharge coefficient particularly at the laminar flow regime whereas it has inversely effects on pressure head losses. Therefore, geometric parameters are required to be properly designed in order to achieve the desired objective. It has been also found that the orifice discharge coefficient reduces with increasing in Reynolds number for all values of beta ratio especially at the turbulent flow regime and hence adequate must be taken while designing such orifice. The results obtained in the present study have been compared with that predicted from an empirical correlations and they show a good agreement between them. Finally, a statistical analysis has been carried out in order to determine a fitting correlation for the discharge coefficient based on the present experimental data.