Cavitation in Fractal Geometry Orifices

An experimental research of three types of orifices was carried out in a hydraulic circuit. One-hole orifice and two fractal-shaped orifices (von Koch snowflake, Apollonian gasket) were tested. Fractal-shaped orifices had lower pressure loss in non-cavitating regime. For cavitating conditions, von Koch snowflake orifice maintained the reduced pressure loss, while pressure loss curve within Apollonian gasket orifice gradually aligned with that of one-hole orifice. Dynamics of the cavitating flow behind the orifices featured distinct peak for one-hole orifice connected with shedding of one strong coherent vortical structure, while pressure amplitudes for fractal-shaped orifices (especially von Koch snowflake orifice) were significantly lower. This conclusion is attributed to multiscale behavior of the flow behind the fractal-shaped orifices.