EXPERIMENTAL STUDY ON FLOW THROUGH UNDERSLUICES

Abstract

Sluice gates are widely used for measuring, controlling and regulating the flow. The situation in which sluice gates are Used are quite different from each other. At times, they are placed on,a horizontal floor, whereas in case of diversion structures they are placed on a raised crest. A situation different from theSe occurs when such gates are placed in the undersluice pocket of barrages. Here, the floor is neither horizontal nor a raised one. The discharge characteristics of these gates ere strongly influenced by the location in which they are provided. For sluice gates on horizontal floor these characteristics have been studied by Henry (2) whereas for sluice gates on a raised crest Ranga Raju and Visavadia (5) and Ranga Raju and Gopalakrishna (4) studied these characteristics. Recently some studies concerning discharge charact;- eristics of undersluice gates were carried out by Sanjay(7). On the basis of limited data some preliminary results were given by him. Since no other data were available in the literature to examine the adequacy of these results, it was felt desirable to collect some additional data in the present study for this purpose. Experiments were carried out in a rectangular channel 7.0m long and 0.4m wide and data were collected with and without an excluder. Excluders' of 40mm and 25mm heights were used in the present study and the downstream slope of sloping glacis was kept1V:2H. For undersluice gates without vii silt excluder, the discharge coefficient Cd in discharge equation Q = B a cdN12gHI was found to depend on H1/a'a/gHl and Sd. The value of Cd has also been related to Cc and H1/a. The values of Cc for undersluice gates are found to be greater than— the values_ of Cc for sluice gates on a horizontal floor. The discharge equation for flow through the excluder as proposed by Sanjay (7) is found to be satisfactory, provided frictional losses in the excluder tunnels are taken into account. For the flow condition when the flow is through both excluder and sluice gate, the ratio of gated flow discharge Q0 to excluder discharge Q was e found as a function of He/a. And this functional relationship was independent of excluder height. Finally for the gated flow when the excluder is blocked, the discharge equation Q'0 )0.87(He)0.5 = 1.13 x 10-6(R1)O.87(He)0.5 has been proposed . a and it is found that there is an increase in sluice gate discharge as compred to thr, Oi'schargo.when both (7,.cludei-and sluice gate are operating. Need for collection of some more data has been identified.