| Spillway design is firstly to meet the requirements of discharge and energy dissipation. Stilling basin with T-type baffle with its structure stability, not only can obviously increase energy dissipation rate, but also can reduce basin length, increase economic efficiency. A new type of energy dissipater presented in this paper:T-type baffle with deck, can solve the problem of energy dissipation under flow's long range, the deck can also effectively prevent torrent upward.In addition to checking spillway's discharge capacity, this paper mainly studied T-type baffle's structure improvement and its shape optimization, through model test and theoretical analysis. The main research results include:1. The relation of flow and its water level under weir is given, and the relation of gate opening and its flow with different number-hole is also given for practical reference. The vary regularity of water surface route within diamond-shaped shock wave is studied. Hydraulic parameters formula of shock wave is deduced.2. The formula of T-type baffle's friction factor, resistance and energy dissipation rate is deduced, which are verified that can be used in practical calculation. The formula of energy dissipation rate can be used for whatever stilling basin is rectangular or trapezoidal, and whatever elevation of basin's bottom and section after jump is equal or not equal.3. Under the model's conditions, stilling basin's optimum length is 52.5m, and T-type baffle's optimal structure and parameters are also given:(1) T-type baffle should be with deck, and deck's optimal parameters is given. (2) T-type baffle's optimum shape:the leg should be ladder type, the former pier should be arc. Chart of its specific type and size is also given. (3) The important factors which affect energy dissipation is given:blocking rate, baffle's relative location. The former pier's maximum water resistance area should be not more than 50%, baffle's relative location is desirable 0.73. Froude number is the main factor which affects energy dissipation rate, and relation of energy dissipation rate and Froude number of T-type baffle is also given.4. Velocity distribution of stilling basin with T-type baffle is given. By analyzing velocity it concluded that the model's T-type baffle cavitation occur possibility. The baffle's optimum shape is given from the point of cavitation. The formula of cavitation number is given, and suggested elevation location of chute setting aeration facilities is also given. |
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