Development of Efficient Stilling Basins for Pipe Outlets

Abstract

The results of experimental work leading to the development of shorter and improved stilling basins for pipe outlets are reported. The original USBR impact type VI stilling basin incorporates a floor that is depressed below the invert elevation of the pipe outlet. In the present study, efforts are made to develop an efficient stilling basin keeping the floor at the invert elevation of the pipe outlet. Experiments were conducted for two pipe diameters with Froude numbers ranging from 1.70 to 5.50. The new models were developed by conducting systematic experiments on a large number of stilling basins with different configurations of the appurtenances such as the splitter block, impact wall, baffle blocks, and end sill in terms of their shapes, sizes, and locations. A performance number has been defined to compare the performances of various stilling basins using a constant experimental running time and same erodible material for each model. The shapes and sizes of various appurtenances and corresponding performance results are presented. The performance of the newly developed efficient and economical stilling basins are compared with the performance of the USBR impact type VI stilling basins for pipe outlets within the range of the Froude numbers tested.