Water tunnel simulation study of the later stages of water entry of conical head bodies

The feasibility of utilizing a water tunnel for studying the cavity-running phase of water entry was explored in this test program. Using conical head models, steady state ventilated cavity tests were conducted in the 12-inch water tunnel to determine cavitation number versus cavity length, pressure distribution, ventilation air flow coefficient and cavity area coefficient. Following these steady-state tests, a cavity attrition test was performed to simulate the decay of the cavity in the last stage of water entry prior to fully wetted flow. The results are interpreted as an indication that quasi-steady analysis may be useful for studying water entry phenomenon at least for decelerations of the order of 3 ft/sec/sec.