Experimental study of scour morphology from plunging water jets

Abstract

Scour due to plunging water jets is a key topic in hydraulic engineering. This study presents the topography of the scour hole formed by water jets from circular nozzles in the downstream pool. Experimental studies for topographic changes in the downstream pool are limited in the literature. Several experiments were carried out to determine scour morphology due to turbulent water jets obliquely impinged on the downstream pool. The topographic changes, maximum scour depths, volume of scour hole and upstream and downstream slopes of scour hole at the equilibrium time were studied in detail. The densimetric Froude number and impingement angle affect the scour morphology. The volume of scour hole increases with the increase of densimetric Froude number and the decrease of impingement length. The topographic maps clearly show that the water jet affected the scour with the decrease of its velocity due to contact with the air at large impingement distances. Moreover, the upstream scour hole angle is approximately equal to the downstream scour hole angle. The findings will be useful in hydraulic applications such as design of plunge pool of an impinging jet spillway, bottom outlet structures, pond water aeration systems, outlets of culverts and storm drainage pipes.