| Air flow distribution is an important design element in a turbojet combustion chamber,which directly affects the combustion efficiency,outlet temperature distribution,ignition characteristics and other performance indexes of the combustion chamber.In this paper,the combustion chamber of a micro-turbojet engine under development is taken as the research object,and related research is carried out from three aspects of flow distribution acquisition,the influence of flow distribution on combustion effect and the geometric design method of flow distribution.Firstly,the computational fluid dynamics(CFD)method was selected to obtain the flow distribution of the combustor in consideration of the micro-scale characteristics of the micro-turbojet combustion chamber.Through grid independence verification and wall roughness influence study,the relevant Settings of simulation calculation are determined.Secondly,the corresponding combustion efficiency is obtained by adjusting the intake air in each area of the combustion chamber according to the gas separation test bed,and the flow distribution scheme which makes the combustion efficiency higher is estimated by response surface method.Then a combustor flow pressure model which can predict the combustor pressure distribution under the condition of known flow distribution is constructed and verified,and the current flow coefficient prediction methods are compared and studied.Based on the combustor flow and pressure model and the linear semi-empirical method,a flow scaling fitting method was proposed,which used one-dimensional calculation instead of numerical simulation for data acquisition and fitting.Finally,the layout of the combustor jet hole is studied.Based on the flow scaling fitting method,the flow allocation design effects of the three layout strategies of fixed number layout,quantitative sizing layout and preferred layout were compared and analyzed,and the iterative optimization characteristics of the flow scaling fitting method were verified.The design effect of area geometry method is tested.The geometric method of flow resistance is proposed and its calculation formula is derived.The design and iterative optimization results of this method are studied. |
