Research On Design And Performance Of Auxiliary Power Unit Reverse-flow Combustor

With the development of science and technology, the development of aviation technology is becoming more and more skillful and the development of large aircraft is more and more important. The engine is essential to the aircraft power system, so the research of auxiliary power system draws more and more attention. The core part of the auxiliary power unit is the combustor, and the performance of the combustor is directly related to the performance of the auxiliary power unit. The paper is on research design and performance of the auxiliary power unit reverse-flow combustor. Design and optimization of reverse-flow combustor model with dome eddy plates are carried out in this paper, and there are three kinds of flame tube domes(Sectional rectifying plate, Continuous rectifying plate, Piecewise continuous rectifying plate) that are designed. Numerical calculation and analysis of overall performance of combustor are carried out in the means of Fluent software, and performance estimation of ignition, blow-out and emissions of the combustor is carried out based on the calculation by the way of semi-empirical formula which has been verified by experiments.First of all, performance estimation of reverse-flow combustor model with dome eddy plate is carried out which is based on non-premixed combustion model. Through the comparative analysis of the flow field, temperature field, outlet temperature distribution factor and the overall performance of the combustor with the numerical calculation of reverse-flow combustor with different domes that was designed. It is concluded that the formation of the recirculation zone of the flame tube head is mainly caused by the combined action of the internal and external bypass primary holes inclined to hedge and dome eddy plate. The strike of external primary combustion hole and rectification of the eddy plate play as a leading role, the inner primary combustion hole plays as an auxiliary role. In the meantime, the circumferential flow generated by the rectifying plate which can improve the flame-linking ability of the combustor. The improvement of the combustion chamber flame tube with the eddy plate has little change in the combustion efficiency, but its OTDF gets improved obviously.Then research on the performance of ignition, blow-out and emissions of the combustor. In this paper, research based on numerical calculation and the semi-empirical formula witch has been verified by experiments on the performance of ignition, blow-out and emissions of the combustor. Finally, the semi-empirical formula for ignition, blow-out and emissions of the combustor can be predicted for the design and performance analysis of the combustor, and provides reference for the design and experiment of the combustor.Finally, through the different turbulence models used in reverse-flow combustor to analyze the performance of it. It is concluded that the large eddy simulation method can obtain the flow field in the combustor which can reflect the flow of the combustor much more accurately. The LES's total pressure recovery coefficient of combustor is 0.9753, the combustion efficiency of the combustor is 0.9926, the outlet temperature distribution factor of the combustor is 0.32, and the RANS's total pressure recovery coefficient is 0.9727, the combustion efficiency is 0.9907, the outlet temperature distribution factor is 0.37. In the overall performance of calculating combustor, compare with RANS, LES is better. In the meantime, research based on the large eddy simulation method on the performance of ignition, blow-out and emissions of the combustor.