Effect of Ventilation to Abrasive Suspension Jet Under Submerged Condition

Abstract

High-speed water jet shows a peculiar processing property in cutting submerged objects, but its processing ability decreases quickly with the standoff distance under submerged conditions. For improving the performance of submerged cutting by abrasive suspension jet (ASJ) a ventilation nozzle system has been developed but the flow structure of ventilated jet is still unclear. Focused on the effect of ventilation, high-speed camera observations of air ventilated submerged water jets are conducted in this work and the structure of air ventilated ASJ is identified by similarity analysis. Experiments show that air-coated suspension jet may be generated by increasing the ventilation flowrate to a certain extent so that ventilation air spreads out of the sheath in the form of large cavity covering the jet. The air-coated jet pulsates periodically and the dominant frequency of air-layer pulsation decreases with increasing of the ventilation flowrate. The Strouhal number of jet pulsation is dependent upon an altered cavitation number. The performance of air-ventilated ASJ is then examined by cutting tests with specimens of aluminum alloy under different ventilation conditions. The result demonstrates that the kerf depth of air-ventilated ASJ in submerged condition reaches to almost the same level of ASJ cutting in air. The cutting ability of ASJ in submerged condition is effectively enhanced by air ventilation.