Experimental Characterization of Supercavitating Finds Piercing a Ventilated Supercavity.

摘要

This report presents the results from water tunnel experiments on supercavitating fins performed at the Garfield Thomas Water Tunnel of the Pennsylvania State University's Applied Research Laboratory. Finite span fins with wedge cross sections piercing the boundary of a ventilated supercavity were tested over a range of conditions. Lift, drag, and shaft torque were measured using a six degree-of-freedom force and moment transducer. Tunnel velocity, cavity size, fin chord, angle of attack, and sweepback angle were varied systematically. For all conditions, gas was entrained in the low pressure base wake produced by the fin, forming a ventilated trailing cavity. At low angles of attack, the cavity formed from the trailing edges of the fin's pressure and suction sides. At higher angles of attack, the suction side of the fin ventilated, which resulted in cavity formation from the leading and trailing edges of the fin's pressure side. A decrease in lift and shaft torque was observed when the fin ventilated, along with a rearward shift in the center of pressure. Unsteady state tests were performed where the fins were oscillated about their spanwise axis over a range of rates and angles.