Research On Combustion Performance Of 5kW Micro Combustion Chamber Under Variable Operating Conditions

Distributed energy systems have risen rapidly in recent years,,and micro gas turbines have received extensive attention as the core of distributed energy systems.Their application fields cover a wide range,including power generation,shipping,chemical,aviation,automotive,natural gas and many other industrial fields.This article is based on the new thermal management system of electric vehicles in the form of micro gas turbines,and conducts research on the 5k W micro combustion chamber in the system through numerical simulation and test methods.The combustion chamber is designed to work under atmospheric pressure.Given its purpose of use as an automotive thermal management system,it will work in a complex and extreme environment.Therefore,this paper mainly explores the changing law of the flow field inside the combustion chamber under the complicated working conditions of thermal power,inlet temperature and inlet pressure change through numerical simulation,analyzes the outlet temperature and emission parameters of the combustion chamber,and studies its combustion characteristics.And through the experiment to verify the numerical simulation calculation results.In this paper,the numerical simulation process and boundary conditions are introduced in detail from a methodological perspective.A movable test bench with a 5k W combustion chamber is built,and the instruments and software used for the test are introduced.After completing all the preparations,the reaction mechanism of diesel combustion simulation was first studied,the calculation results of the simplified mechanism and the general contract reaction mechanism were compared,and combined with the research needs of this paper,the general contract reaction mechanism was finally selected to complete the follow-up research work.After selecting the combustion reaction mechanism,the effect of changes in thermal power,temperature and pressure on the velocity field,temperature field and outlet parameters inside the combustion chamber was studied using commercial software.Under complicated working conditions,there is no obvious influence on the position and geometric characteristics of the reflow zone.The length of the reflow zone is maintained at 28-30 mm,and the width of the reflow zone is stable within the range of 23-25 mm.The change laws of temperature field and outlet parameters are similar,showing a positive correlation with load,temperature and pressure,NO increases with an average growth rate of 11%,22.6% and 19% as the load,temperature and pressure increase.Finally,the rationality of the numerical simulation law is verified through experimental comparison.The increase of heating power and inlet temperature will reduce the CO content in the outlet and increase the NO content.The decrease in pressure will result in a reduction in the amount of air,and the amount of air should be supplemented appropriately so that it runs near the designed operating point.From a qualitative point of view,the data change law obtained by the experiment is consistent with the numerical simulation results.But the result of pollutant NO is larger than the simulation result,which may be caused by the numerical simulation ignoring the process of atomization and evaporation.