COMPARISON OF THEORY AND EXPERIMENT FOR VENTED HYDROFOILS. PART 1. ANALYSIS
1963
Fabula, Andrew G.
The work of three precedinreports on the linearized theory of vented hydrofoils is completed by a detailed exposition of the procedure for calculating hydrodynamic coefficients. The basic assumption is steady, plane potential flow with two free streamlines; one detaching at an arbitrary chordwise position and the other detaching at the trailing edge. The single cavity terminates at an arbitrary distance down stream of the trailing edge. The calculation of the key smooth-entry, open-model parameters is illustrated by considering a symmetrical and a cambered profile, each vented at 30% chord. The theoretical C sub D and C sub L curves for two vented hydrofoils with exhaust at 30% chord are compared with water-tunnel test data. The agreement is not as good as in previous compari sons for leading-edge or trailing-edge free streamline detachment. Real-fluid and tunnel blockage effects are believed to have produced the discrepancies. Because the calculations for arbitrary profile involve functions that are independent of profile form the function tables that were generated are given in Part 2 of this report, bound separately.
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