DISCHARGE CHARACTERISTICS OF ORIFICE TYPE p SPILLWAY UNDER OBLIQUE APPROACH FLOW

Abstract

An orifice spiliway is a structure constructed at or near the dam site to dispose of surplus vater from the reservoir to the channel downstream. Orifice spiliways are provided for all darns as a safety measure against Overtopping and the consequent damages and failure. The purpose of this study is to examine the discharge characteristics of orifice spiliway under different approach flow conditions (with straight approach flow, oblique flow (r = 3.72 m) and oblique (r = 2 m) approach flow). For each approach flow condition, we had nine stages for performed whole experimental work. The whole experiments were performed for investigation of discharge characteristics of orifice type spiliway under oblique approach flow, and to study the variation of longitudinal velocity across the width of approach channel for different opening of gates & approach flow condition. It has been observed through analysis the flow characteristics of each hay are different for each approach flow condition. It also have been observed that for operation of same bay with different approach flow condition the discharge found to be highest for straight approach flow and lower for oblique approach flow (r = 2 m). It also has been observed that velocity variation across the channel found to be non uniform throughout the channel width for all approach flow conditions and it has been found that in straight approach the velocity variation across the channel was less non uniform as compare to oblique approach.