Anti-singing Edge Effect on Propeller Open Characteristics

Generally, the propeller is applied with an anti-singing trailing edge for the prevention of irregular noise resulted from Karman vortices generated from the trailing edge of the propeller. It is well known that the anti-singing trailing edge exercises a greater effect on propeller open characteristics (POC in short) and propeller shaft speed, the effect of which is to be taken into account when propeller pitch is decided accordingly. On the other hand, in the propeller open test (POT in short), the finished accuracy of the trailing and leading edges greatly influences test results; however, it is difficult to attain higher accuracy on the very thin trailing edges of the propeller model. As a result, the effect of the anti-singing trailing edge is studied experientially in spite of a greater effect of the anti-singing trailing edge upon the POC. With this research based on the POT using 400 mm diameter model propellers in the two different conditions, without (case-A) and with (case-BJ the application of anti-singing trailing edge, the POC prediction was made through several calculations by means of potential flow theory (lifting surface, source and quasi-continuous vortex lattice method (SQCM in short), surface panel method) and generally applicable CFD. Although the calculation results by the potential flow theory overestimated the values of differences of thrust and torque between case-A and case-B respectively, the CFD calculation result showed a closer agreement with the POT results. Finally, a reasonable agreement was verified between the CFD calculation result and the sea trial results with the full-scale vessel.