Accession Number : ADA296637

Title :   A Computational and Experimental Study of Viscous Flow Around Cavitating Propulsors.

Descriptive Note : Technical rept.,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF OCEAN ENGINEERING

Personal Author(s) : Brower, Wesley H.

PDF Url : ADA296637

Report Date : JUN 1995

Pagination or Media Count : 113

Abstract : A method for analyzing viscous flow around partially-cavitating and super-cavitating hydrofoils is presented. A nonlinear perturbation potential-based panel method is used to first solve the cavity solution in inviscid flow. A boundary layer solver is then applied on the surface bounded by the union of the foil and cavity surface. The effects of viscosity on lift and drag are studied for both partial and super-cavitating hydrofoils. Viscosity is shown to have a substantial effect in the condition of partial cavitation: on the other hand, minimal deviations from the inviscid solution are observed in the case of super-cavitation. Finally, the applicability of the present method to analyzing the viscous flow around cavitating propulsors is discussed. Experiments are performed at the MIT Variable Pressure Water Tunnel to ultimately assess the validity of coupled inviscid/viscous cavity analysis method. Velocities are measured along a rectangular control surface surrounding the hydrofoil, in the boundary layer region, as well as in the proximity of the cavity surface. The cavitation number is evaluated by measuring the pressure inside the cavity via a manometer. The measurements are compared to the numerical results from the coupled, nonlinear, inviscid cavity analysis method and a boundary layer solver. Forces are computed from measured velocities via momentum integrations and are compared with those predicted by the numerical method. (AN)

Descriptors :   *BOUNDARY LAYER, *VISCOUS FLOW, *CAVITATION, *HYDROFOILS, VELOCITY, ALGORITHMS, TURBULENT FLOW, COMPUTATIONAL FLUID DYNAMICS, PRESSURE MEASUREMENT, PROPULSION SYSTEMS, FLOW FIELDS, SOLUTIONS(GENERAL), RECTANGULAR BODIES, CONVERGENCE, HYDRODYNAMIC CODES, PERTURBATIONS, NONLINEAR ANALYSIS, TWO DIMENSIONAL FLOW, NUMERICAL METHODS AND PROCEDURES, DRAG, LIFT, INVISCID FLOW, VISCOSITY, LAMINAR FLOW, PRESSURE DISTRIBUTION, MOMENTUM, CONTROL SURFACES, VARIABLE PRESSURE.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE