Study of Flow Characteristics Over a Rounded Edge Drop Structure in Open Channel

S M Kori,M Channa,A A Mahessar,A A Memon,A R Kori

doi:10.48084/etasr.2584

Abstract

Flow over a drop structure is a form of free overfall called hydraulic drop. Hydraulic drop changes the nature of flow abruptly from sub-critical to super-critical condition. Rapidly varied flow analysis is a complex phenomenon and involves remarkable characteristics. Some of the drop structures constructed in Sindh and Punjab provinces of Pakistan had gone through diverse failures, consequential in interruption of water supply to irrigation fields encountering substantial economic loss. In the present study experiments were carried out in the hydraulic laboratory of Mehran University of Engineering and Technology on round edged drop structure fitted in a horizontal rectangular flume (channel model). Data regarding hydraulic drop and hydraulic jump characteristics were collected during the experiment. The observed data included: flow discharge (Q), radius of rounded edge drop structure (r), height of the structure (h), hydraulic drop length (Ld), hydraulic jump length (Lj), depth of flow at toe of the jump (Y1) and tailwater depth (Y2). Applying dimensional analysis, the non-dimensional parameters of the observed data were calculated. Using statistical analysis, empirical relationships among the non-dimensional parameters were established for the appropriate design of the drop structure. The research results showed that the length and depth indices are functions of D=q2gh3 and r/h values. It was also found that for rounded-edge drop structure, the length of the stilling basin (LSB) reduces as r/h ratio increases

Highlights

Enormous water resource engineering projects have been built up all over the world
Water load on downstream apron increases, thereby counteracting the uplift in case of structure laid on permeable foundation
Authors in [14] extended the work of [5] and developed a series of empirical formulas concerning the hydraulic characteristics of flow over straight drop structure on the cumulative bed slope in the rectangular channel:

Summary

INTRODUCTION

Enormous water resource engineering projects have been built up all over the world. Such man-made interventions, like weirs, barrages, dams, regulators, drops, etc. are key structures for supplying water to agriculture fields and other purposes at safe velocity through conveyance infrastructure. Author in [13] conducted research on the characteristics of flow through a rounded edge drop structure in a rectangular sloping bed channel. He did not take into account the radius of rounded edge of structure, and considered the cumulative bed slope of the channel during the analysis He developed depth and length indices relationship of hydraulic drop and hydraulic jump with drop number (D) as:. Authors in [14] extended the work of [5] and developed a series of empirical formulas concerning the hydraulic characteristics of flow over straight drop structure on the cumulative bed slope in the rectangular channel:. Authors in [2] worked on the flow characteristics of a round drop structure in a rectangular sloping bed channel and developed empirical formulas for the proper design of drop structures as:. Using non-dimensional parameters, empirical relationships of length and depth indices were developed in terms of D and r/h for appropriate structure design

APPLICATION OF HYDRAULIC JUMP FORMATION

EXPERIMENTAL WORK

Equipment Setup and Data Collection

RESULTS AND DISCUSSION

CONCLUSIONS