Experimental study on ice breaking by a cavitating water jet in a Venturi structure

Abstract

Ice breaking by a cavitating water jet based on Venturi structure is studied experimentally. Systematic researches of cavitating water jet interacting with ice are carried out by doing indoor experiments, where the cavitating jet is generated by a tailor-made device through Venturi nozzle and the circular fresh-water ice plates are made of boiled water in a cryostat. The whole evolution of cavitating jets and ice plates is recorded by two high-speed cameras from two views simultaneously. Pressure loads on the rigid wall of cavitating water jet is compared with that of conventional non-cavitating water jet and the change is analyzed. Among two typical structural parameters of Venturi cavitating nozzles selected in this paper, the ratios of throat length to diameter ε (1; 1.5; 2) and the diverging angles α (8°; 10°; 12°), the nozzle withε = 1 andα = 12° is found to be the best in terms of loads on wall. On this basis, the responses of ice plate, including crack generation, crack development and fracture, are studied under the cavitating jet loads, mainly involving the compressible pressure P1 and cavitation pressure Pc. According to the main cause and propagation sequence of cracks, the failure mechanisms of ice under Venturi cavitating jet can mainly be divided into three types: shock waves failure, overall strength failure and local strength failure, along with six damage patterns roughly. Furthermore, the effects of ice plate thickness, cavitating water jet strength and boundary conditions are also investigated.