Thermal Control of the Test Liquid in Vibratory Cavitation Erosion Tests

摘要

Implosion of vaporous cavities is exothermal, thereby heating the cavitating liquid. In vibratory cavitation erosion (VCE) tests the erosion rate increases with test liquid temperature. In order to obtain the erosive properties of a given material at a given temperature, it is necessary to control the test liquid temperature. The prevailing ASTM standard specifies cooling of the test liquid, and allows a maximal temperature rise of 4 deg C during the VCE test. However, cooling alone does not ensure the required uniformity of test liquid temperature near the specimen. In order to obtain a uniform test liquid temperature near the specimen during VCE tests, a thermal control system is recommended. This system consists of three subsystems for cooling, heating, and mixing the test liquid. Correct location of the temperature sensor and operation of the thermal control system improve the thermal control appreciably. This control method was used during 24 VCE tests with water as a test liquid. The average temperature rise in these tests was 1.5 deg C during the transient stage and 0.2°C during steady state operation.