VISCOUS SCALE EFFECTS ON PROPELLER TIP VORTEX CAVITATION

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VISCOUS SCALE EFFECTS ON PROPELLER TIP VORTEX CAVITATION

Viscous scale effects on propeller TVC were investigated by testing a series of three geosim propeller models in the large cavitation Tunnel of CSSRC without and with two different turbulence stimulators. Tests included flow visualization by oil film method and cavitation observation for five different stages of development of propeller TVC: desinent, unattached, attached, developed and fully developed TVC. The main findings are: 1)there existed a size effect of the boundary-layer transition on propeller models which could be analyzed by using the critical roughness Reynolds number and a newly defined quasi-critical Reynolds number, 2)the preliminary results of the blackboardpaint used as a tripping device was encouraging, 3)the Reynolds number exponent n of TVC scaling rules was found to be dependent upon the blade surface condition, the stage of development of TVC and the thrust loading of propeller models.