Circular Flow Tunnel Of Hydraulic Transient Problems

Free flow circular tunnel are widely applied in hydraulic tunneling engineering as open channel flow conveying because of its good stress condition, being convenient to mechanized construction and favorable in hydraulics.Usually, steady flow theory is used in engineering design,but unsteady flow appears frequently,because of control and accident ,etc. during practical operation.Therefore there are potential problems in operation. To solve these practical problems, we should study the hydraulic transient problems in circular unfull tunnels of water delivery project. The main contributions of the thesis are as the following:(1) The derivation of shallow water theoryAccording to higher-order shallow water theory under four basic assumptions,through simplification of width-integration, depth-integration and nondimensionalization of the equations,the higher-order shallow water equations for prismatic unpressurized tunnel with circular cross-section are derived based on Reynolds equations. The three-dimensional flow problem is transformed to one-dimensional one by simplification above ,for which first order shallow water theory can be considered as a particular case of higher-order shallow water theory.(2) Numerical methodsFDM method is applied in the thesis to handle the equations of higher-order shallow water theory.Symbolic language, Mathematica ,is used in calculation,so that large scale mathematical manipulations can be treated conveniently and the derivation of difference equations are done easily.This is true , especially ,in dealing with higher order derivative terms.(3) The calculation of solitary wave propagationIn connection with the hydraulic calculation of unsteady flow, solitary wave are superimposed on the interrelated hydraulic variables of uniformflow .Based on initial conditions and boundary conditions,the hydraulic variables such as discharge, flow velocity and the depth are obtained from numerical solution of the equations for higher-order shallow water theory. Through the analysis of the results , the security of tunnel operation can be disscussed.(4) The program of caculationThe symbolic software , Mathemaitca, is used to realize numerical caculationof shallow water equations,and the applications of numerical solution to higher-ordershallow water equations is explained in the thesis.