COEFFICIENT OF DISCHARGE OF CHIMNEY WEIR UNDER FREE AND SUBMERGED FLOW CONDITIONS

Abstract

Abstract:The main objective of this investigation is to study experimentally the water surfaceprofiles and to obtain convenient expressions for the estimation of dischargecoefficients (Cd) for free flow over chimney weir and the discharge factor (q/q1) forsubmerged flow. Four chimney weir models with different vertex angles wereconstructed and tested, the surface water profiles, for all models were smooth upstreamand fall suddenly downstream the model and at a high discharge it become concavewhile at law discharge the water surface profile become convex. The coefficient ofdischarge for free flow increase with the decrease of the upstream head and with thedecrease of half vertex angle (θ ). While the discharge factor for submerged flowincrease with the decrease of the submergence ratio (h2/h1). Two general expressionswere optioned, one, for the estimation of Cd with respect of (h/p),(w/p) and θ for freeflow conditions and the other for estimation of the coefficient factor (q/q1) with respectto (h2/h1) and (h1/p).معامل