Investigation of a cavitating film erosion test

Abstract Tests have shown that by continuously replenishing the test liquid in the cavitating film the excessive temperature rise experienced in other similar tests is prevented. The moderate temperature rise that is obtained depends mainly upon the nature and flow rate of the test liquid. Erosion patterns obtained on stationary 16-mm (o.625-in.) diameter testpieces were well-distributed and fairly uniform. Erosion rate reached an early maximum and then decreased with time. It decreased as the separation increased, was proportional to probe amplitude but was not significantly affected by small pressure changes or by the rate of flow of test liquid. Optimum test conditions were obtained with 0.5 mm separation from a 20 kHz (kc/sec) vibrator having a peak-to-peak amplitude of 50 μm (0.002 in.). Rates of erosion of widely different materials were about half of those obtained in a conventional open-beaker test. The test offers distinct advantages over the open-beaker test, especially with regard to the evaluation of weak materials and the control of the test liquid condition in the cavitation zone.