Water tunnel tests of NACA 4412 and Walchner profile 7 hydrofoils in noncavitating and cavitating flows
ABSTRACT The results of force and cavitation tests on two hydrofoils in two-dimensional flow are presented. The hydrofoils are the NACA 4412 profile and a modified circular arc, flat plate, hydrofoil designated as a Walchner profile 7. The results of experiments performed in wind tunnels and in other water tunnels are presented for comparison. The experiments described in this report are the first tests using the High Speed Water Tunnel two-dimensional working section and the new force balance; therefore, the experimental setup, procedure and methods of data reduction have been described in detail.
The results of the tests on the NACA 4412 hydrofoil are in good agreement with those obtained for this profile in the Langley two-dimensional low-turbulence wind tunnel. The results of the tests on the circular arc, flat plate hydrofoil are not in good agreement with the results obtained by Walchner for cavitating flow. The differences in the forces on the hydrofoils can be accounted for with a difference in cavitation number of approximately 0.1.
The tests indicate that accurate force measurements can be made with the new water tunnel force balance and that the methods developed during these tests provide a satisfactory means of obtaining the section characteristics of hydrofoils in cavitating and noncavitating flow.
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ABSTRACT: An investigation in the High Speed Water Tunnel of the two-dimensional hydrodynamic characteristics of sharp-edged hydrofoils is described. The lift, drag, and pitching moment were measured in cavitating and noncavitating flows for flat plate and circular arc profiles. The theory of Wu for the forces on sharp-edged profiles in full cavity flow and the experimental results showed good agreement over a wide range of attack angles.
Article: Hydrodynamics of Pumps[Show abstract] [Hide abstract]
ABSTRACT: The subject of this monograph is the fluid dynamics of liquid turbomachines, particularly pumps. Rather than attempt a general treatise on turbomachines, we shall focus attention on those special problems and design issues associated with the flow of liquid through a rotating machine. There are two characteristics of a liquid that lead to these special problems, and cause a significantly different set of concerns than would occur in, say, a gas turbine. These are the potential for cavitation and the high density of liquids that enhances the possibility of damaging unsteady flows and forces.