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Oblique impingement of circular water jets on a plane boundary

Author(s): A. Jalil; N. Rajaratnam

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Keywords: Water jet; turbulent jets; oblique impingement; hydraulics; erosion

Abstract: This paper presents the results of an experimental study on the oblique impingement of turbulent water jets of diameter d equal to 50.8, 101.6 and 152.4 mm, placed above a horizontal plate at vertical distances varying from 45 to 255mm and at impingement angles of θ with the plate equal to 15°, 30°, 45°, 60° and 75°, with the velocity of the jet in the approximate range of 3–10 m and the jet Reynolds number varying from 380,000 to 720,000. The deflected jet was mostly in the forward direction with very little backward flow for θ < 45°, which increased to an estimated value of about 5–10% for larger angles of impingement. The forward flow in the deflected jet or stream was in the supercritical state. The thickness profile of the deflected jet in the centerplane was similar for all the experiments if plotted in terms of a suitable scale which was either the thickness at the normalized distance from the impingement point x/d = 1.0 or 5.0, for x/d up to about 20. These scales in terms of the jet diameter varied mainly with the angle of jet impingement. The transverse thickness profiles in the deflected jet were also found to be similar. The velocity profiles in the boundary layer of the deflected jet were similar and its thickness δ remained constant for x/d up to about 7.5 as in the case of stagnation flows. The boundary shear stress τ0 appeared to increase first with the distance from the impingement point and then decrease as in the case of the impingement of submerged impinging jets.


Year: 2006

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