The cavitating venturi is using to provide constant mass flow rate of liquid which is passing through a passage, independent of downstream pressure changes. A cavitating venturi is a converging-diverging nozzle with a suitable throat area for passing flow. The flow rate is a function of the upstream pressure, the throat area, the density and saturated pressure of the liquid. An experimental setup with the capability of supplying constant water flow rate, upstream pressure and temperature was designed and manufactured. Three cavitating venturies were designed and built to investigate the effect of cavitating venturi size on its mass flow rate and capability of performance venturi in wide ranges of flow rates. Three different sets of experiments were conducted to ensure the performance of the venturi to keep constant mass flow rate independent of downstream pressure. In the experiments, under different downstream and upstream pressure conditions, the mass flow rates were examined. The results show that if the ratio of downstream pressure to upstream pressure is less than 0.8, the mass flow rate is constant and independent of the downstream pressure. Whenever pressure ratio exceeds from 0.8, the venturi acts like an orifice.
