Erosion by Impinging Circular Turbulent Jets

This paper presents an experimental study of the erosion of loose beds of sand and polystyrene by impinging (submerged) jets of air and water. The maximum depth of erosion increases linearly with the logarithm of time up to a characteristic time value beyond which the variation becomes nonlinear and eventually approaches an asymptotic state. For large impingement heights, the asymptotic values of the maximum depth and radius of erosion in terms of the impingement height have been found to be mainly functions of the densimetric Froude number divided by the impingement height in terms of the diameter of the jet at the nozzle. Some correlations have also been found for small impingement heights. The geometric form of the eroded bed profile, in the unsteady as well as in the asymptotic state, has been found to be similar.