The Influence of Pressure Gradient on Desinent Cavitation Produced by the Separated Flow from an Isolated Triangular Surface Protrusion,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
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An experimental investigation studied the desinent cavitation characteristics of various sizes of two-dimensional triangular protrusions in a turbulent boundary layer for favorable, zero, and unfavorable pressure gradients. Eight roughness heights h were employed in the studies ranging from 0.01 to 0.30 inches. The relative height hdelta varied from 0.026 to 2.53. Desinent cavitation numbers sigma sub d were obtained visually over a velocity range of 30 to 60 fps at an average total air content of 3.7 ppm mole basis. The data for zero pressure gradient were in fair agreement with data obtained for the same protrusion shape by Holl 1958. The cavitation number was correlated with relative height, Reynolds Number and Clausers 1954 equilibrium boundary layer shape factor which includes the effect of pressure gradient. The data show that sigma sub d increases with pressure gradient. This result was not expected since it appears to contradict the trends implied by the so-called characteristic velocity theory developed by Holl 1958.