Effect of Beta Ratio on Performance of Nozzle Meter

Nozzle meter is a differential flow measuring device installed in a pipe line to measure the flow rate. The actual flow through the nozzle meter is lesser than the theoretical flow because of the losses occurred in the nozzle meter. Coefficient of discharge (C_d) is to be used to get actual discharge from theoretical discharge which depends on Beta Ratio (ratio of throat diameter to the pipe diameter) of nozzle meter and Reynolds Number. In the present work, the experimental investigations are carried out on a nozzle meter with standard long radius nozzles ISO 5167 of beta ratio (d/D) 0.4, 0.5, 0.6, 0.7 and 0.8. It is found that C_d is independent of Re when Re>10⁵. However C_d depends on beta ratio (β). A unified equation has also been developed for calculation of discharge for any beta ratio of nozzle meter and Reynolds number.