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.
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ABSTRACT: Historically, two-dimensional airfoil or hydrofoil section characteristics have been obtained by measuring individually the lift, drag and pitching moment by the most accurate technique available. The use of force balances to measure the three quantities simultaneously has met with only partial success. Although the lift and pitching moment data have usually been acceptable, the drag data have varied by as much as an order of magnitude from previous reference data. To investigate the parameters which influence two-dimensional force measurements, an experimental program was conducted in the subsonic wind tunnel of the Applied Research Laboratory at The Pennsylvania State University. From the results of this test program, the sidewall boundary layer was identified as the primary factor contributing to the erroneous drag measurements. A correction procedure which is based on the airfoil/hydrofoil geometry, the flow environment and the measured data was developed. Corrected data from the subject test program and from similar programs in other experimental facilities for both symmetrical and cambered sections are in good agreement with the reference data in all cases.Journal of Aircraft 05/1984; -1. DOI:10.2514/3.45112 · 0.49 Impact Factor