Comparison Tests for Checking Relations for Cavitation Scale Effects

The problem with model tests for cavitation phenomena are the so-called “scale effects”. There are numerous examples where the model was observed to be cavitation free at design operation conditions, however, the prototype suffered extensive cavitation to severe damage under similar conditions. The real heart of a successful cavitation study is to scale the information from model test to prototype conditions correctly. Therefore many efforts are made world wide to find relations for the most crucial scale effects associated with size and velocity. After carrying out extensive test series on all kinds of test body families at the VAO, by taking care of the test water quality with respect to its cavitation susceptibility, strikingly simple and clear relations for scale effects appeared. In order to check these scaling relations comparison tests were carried out in three different institutes: The Brodarski Institute (BI) in Zagreb, the Wuhan University (WHU), and the China Ship Scientific Research Center (CSSRC) in Wuxi. The test results of the model body families tested in the new CLCC at CSSRC do not confirm the velocity scaling relation found at the VAO, however, this velocity scaling relation is confirmed very well by the results of WHU and BI. On the other side all results do show a distinct size scale effect and confirm the size scaling relation.