Scale effects of incipient cavitation for high-speed flows

The scale effects of incipient cavitation in high-speed flows have been studied in experiments in which series of sudden enlargements in pipes with different expansion ratios are employed. The relationship between the incipient cavitation and flow velocity is also investigated and shows that the scale effect indeed exists. Based on the test data, an empirical formula for incipient cavitation that takes scale effects into account is derived and validated. The formula has been validated with corresponding experimental data and good agreement has been obtained. The proposed formula can be used to forecast incipient cavitation of hydraulic structures in prototype with high-speed flow.