Numerical Simulation Of Three-dimensional Turbulent Flow In Gas Turbine Combustor

Gas turbine is widely used for generating mechanical power in aviation,navigation and electric power stations. This is a subject discipline developed from advanced science and technology. There,combustor is a key component which is more complex than other components. In studying the working principles of the gas turbine combustor,theories in gas dynamics,heat transfer,mass transfer and chemical reactions have to be applied.In the past years,design of gas turbine combustor depends mainly on empirical formulae derived from experimental data. With the rapid development of both computer hardware and software including combustion theory and computational fluid dynamics,numerical simulation has become more and more important. Applying numerical simulation to design combustor can improve its reliability,reduce the cost and protect the environment by dispersing less pollutants,taking an important step in developing gas turbine.In this thesis,numerical simulations of three-dimensional turbulent reacting flow in gas turbine combustor were studied. Mathematical models of the combustor are developed by:a) Applying a modified k-s turbulence model to calculate the turbulenceparameters with large swirl and axial velocity gradients in the combustor.b) Applying the multi-fluid model to study premixed combustion in thecombustor with the fluid being separated into 11 components,the air/fuel ratio being taken as the dominating attribute.c) Including thermal radiation effects by the six-flux model of radiation.d) Applying the curvilinear coordinate system for the complex geometry ofdiffusers.e) Applying the inter-phase slip algorithm IPSA method to solve the set ofdiscretized equations.In developing the mathematical models of the combustor,a general numerical simulation program to simulate gas turbine combustor is drawn up. The industrial combustors are chosen to validate the program. The nonreacting flows for two combustors with different shapes are simulated. The results are compared with experimental data. It is found that the predicted results agreed well with experiments.Further,the reacting flows for an aeronautical engine flame tube is also simulated. The distributions of velocity,pressure,turbulent kinetic energy and its dissipation rate,turbulent viscosity,temperature,density,oxygen,enthalpy,fuel,fuel/air ratio,production,radiation flux along the three directions for every fluid component are predicted. Results are compared with those predicted by using an eddy-break up model. This is a good demonstration that the models developed in this thesis can be applied to yield better prediction results.Results from this thesis concluded that numerical simulation can be applied to study "effect of varying the incident angle of dilution air on the performance of the gas turbine combustor".