Asian Journal of Engineering and Technology (ISSN: 2321 – 2462) Volume 03 – Issue 05, October 2015 Asian Online Journals (www.ajouronline.com ) 494 The Discharge Coefficient for a Compound Sharp Crested V- Notch Weir Abdel Azim Mohamed Ali 1 , Mohamed Ibrahim 2* and A. I. Diwedar 3* 1 Associate Professor, Hydraulics Research Institute, National Water Research Center, Egypt 2 Lecturer, Shoubra Faculty of Engineering, Banha University, Egypt 3 Researcher, Hydraulics Research Institute, National Water Research Center, Egypt * Corresponding author’s email: adiwedar [AT] gmail.com ____________________________________________________________________________________________________________ ABSTRACT---- This paper presents experimental work to investigate the discharge coefficient for a compound V- notch weir. This weir is composed of two triangular parts with distinctive notch angles. Fundamental standards were utilized to connect the release to the significant geometrical and hydraulic parameters in non-dimensional form. Physical model tool was used, where more than 30 runs were executed in a rectangular flume. Five weir models were tested representing different weir characteristics. The outcomes were contrasted with previous work, the discharge coefficients were found in a decent concurrence with the comparable compound sharp-crested weir. The study demonstrated the principle point of preference of the proposed compound weir to allow a decent exactness in the flow measurement for a varied range of flows with no cutoffs as well. Keywords--- V-notchWeir, WeirDesign,Hydraulicstructures, Discharge Measuring Structures ______________________________________________________________________________________________ 1. INTRODUCTION Weir is a hydraulic structure set perpendicular to the flow direction with the objective to measure the flow discharge. The weir givesprecise measurement for a different spread of flows. The lower triangular part of the weir managesthe normal range of discharges at the measurement structure, the weir upper part living up to expectations for the unpredictable higher top flows. Weirsare usually used to observe rivers flow keeping in mind the end goal to shield from flooding and bolster navigation in rivers. The V-notch weir is one of the sharp crested weirs with a triangular section, used to measure small discharge values subsequent to the water head over the weir peak that is generally touchy to changes in flow.The compound V-notch weir (composed of two triangular sections) is a new model introduced by [1],utilized for the same purposes of the established one notwithstanding recompense to pass highdischarges. Consequently, the new weir model is permitted to be utilized as a part of numerous canal categories. Unfortunately, few studies were completed on this new sort of weirs, along these lines this study was done to elucidate more fine points of interest concentrating on the discharge coefficient of a compound sharp crested triangular (CSCT) weir model. 2. BACKGROUND The structural parameter of the weir (crest height, notch angle, weir width) affects the weir performance. The geometrical parameters involved in the hydraulic operation of weirs are the length of the weir crest and the shape of the flow control section [2].Various studies have been executed concerning flow of water over weirs, as [3], [4], [5], [6], [7] and [8]. The discharge coefficient speaks to the impacts not considered in the determination of the mathematical statements used to estimate discharge from flow depth. Per to[9] and [10]these effects include surface tension, capillarity, viscosity, velocity distribution in the approach section, and streamline curvature attributable to weir contraction.