Design of stilling basin for circular pipe outlets

Abstract

Experimental work leading to the design of a stilling basin for pipe outlets is reported in this paper. The stilling basin designed on the basis of present study has been compared with the stilling basin design proposed by Garde et al. in 1986. The experiments were performed by taking two pipe outlets of 10 and 7.5 cm diameter and varying inflow Froude numbers. In the present study, the new design is arrived at by conducting a systematic experimentation on the various stilling basin models and keeping the basin floor at the invert level of the pipe outlet. The location as well as the arrangements of appurtenances, such as a wedge-shaped splitter block, modified grid, row of wedge-shaped baffle blocks, and end sill, were also varied in the experiments. A nondimensional number has been defined to compare the performance of the stilling basin models on the basis of developed scour downstream of the basin. The performance of the proposed stilling basin (model M-71) is much better as compared with that of the stilling basin G-D* proposed by Garde et al. in 1986.