Alternate designs of stilling basins for pipe outlets

An experimental work leading to the development of economical and improved stilling basin designs for circular pipe outlet in comparison to Garde's stilling basin [Garde, R.J. & Saraf, P.D., Journal of Irrigation and Power 1986, 145–154], is reported in this paper. In the present study, attempts are made to develop efficient and shorter stilling basin models keeping the basin floor at the invert level of the pipe outlet for inflow Froude number Fr = 5.50. The new designs are arrived at by conducting a systematic experiments on the stilling basin models having appurtenances like a wedge-shaped splitter block, a modified grid, an intermediate sill and a rounded step. Scour index, a non-dimensional number has been defined to compare the performance of the stilling basin models using the same erodible material and time of experimental run. The performance of the newly developed stilling basin models has been compared with that of Garde's stilling basin model G-D^∗. The proposed model M is also compared with the earlier stilling basin model M-12, as suggested by Goel & Verma [Journal of Irrigation and Drainage Systems 15(1), 2001, 81–91].