Numerical Simulation And Experimental Research On An Air-Heater Of Low Total Temperature

The numerical simulation and experimental research on an air-heater of low total temperature were performed to study the influences of its structural parameters and state parameters in this paper.Firstly, a physical model and numerical method are developed to simulate the spray combustion processes in the air-heater fo low total temperature.Three-dimension full N-S equations and two-phase flow model which considers the liquid fuel spray as discrete particles, are employed to describe the combustion processes. The mass and energy transfer between the two phases are calculated by the droplet evaporation model, and the gas chemical reaction rate is calculated by the Eddy-Dissipation model. The spray combustion flow in the air-heater is simulated by using the models and method founded in this thesis, the structural of combustion flow in the air-heater and the combustion efficiency on the axis of the air-heater.Secondly, the parameters that have influences on the performance of the air-heater are analysed and several comparable operations are founded. Then the numerical simulation of all operations are finished. The effect of air flow from injector-inlet, the injectors array, the direction of injectors and the combustion chamber length(Lc) on the combustion efficiency, the combustion chamber cooling and the uniformity of the outlet are analyzed based on the simulation results. The results show that, the air flow from injector-inlet has significant influences on the combustion efficiency and the cooling of injector faceplate; the inner surface of the combustion chamber is protected by air flow from chamber-inlet; the injectors array effects the cooling of injector faceplate but has light influences on the combustion efficiency; the uniformity of the outlet will become worse when Lc is reduced.Finally, observe the effect of air flow from injector-inlet on the stabilization of igniting, the combustion efficiency and the uniformity of the outlet by experiment, The results show that, when the air flow from injector-inlet is low in a range, the combustion efficiency is nearly 100% and fluctuate slightly, the combustion efficiency will decrease rapidly and the uniformity of the outlet will become worse when the air flow from injector-inlet raises out of the range, the air-heater will become unignitable when the air flow from injector-inlet is too large.