Abstract
Test results on the unsteady cavitation in long orifices are presented. Test was carried out under two flow conditions: (i) at constant Q. i. e., both the inlet pressure P1 and the outlet pressure P2 were changed stepwise but the flow rate Q was kept at a set value, and (ii) at constant P1, Le., both Q and P2 were changed stepwise but P1 was kept at a set vabse.
From examination about the effects of oil temperature, pressure, orifice diameter, etc. on the cavitation delay time, it is found that unsteady cavitation is affected significantly by the degree of dissolution of gas nuclei to the orifice inlet. The time required for bubbles to grow to the minimum visible size by diffusion and/or by vapourisation is calculated, and it is shown that growth by vapourisation has an important role in cavitation of long orifices.
