Abstract: The cavitation flow performances of a given Venturi tube were studied to get the steady flow curve and predict the cavitation region based on the realizable k-ε turbulence model and Zwart (Zwart-Gerber-Belamri) cavitation model under the designed conditions with FLUENT software. The throat diameters D of the Venturi tube were chosen as 3mm, 5mm, 7mm and 9mm respectively; and the distances L between the throat and the entrance were 60mm,40mm and 20mm respectively. It can be concluded that: (1) The phenomenon of hydraulic cavitation is the main reason for the steady flow of Venturi tubes; (2) Throat diameter affects the steady flow performance of cavitation. When D is 9mm, the maximum increase of flow rate is 0.13 m³·h^-1; and when D is 3mm, the minimum increase of flow rate is 0.02 m³·h^-1; (3) The distance between the throat and the entrance mainly affects the inception of hydraulic cavitation. When L equals 20mm, the minimum initial entrance pressure of cavitation is 10.77 MPa; and when L equals 60mm, the maximum initial entrance pressure of cavitation is 10.98 MPa.

Key words: Venturi tube, steady flow, throat, cavitation