Study On Analysis Method Of Impact Atomization And Evaporation In Micro Combustor With Vaporizer

People’s demand in micro power equipment has increased with the advancement of science and technology and turbine engine also has developed to a branch tends to be microminiaturization.As the core part of the engine,the combustor is often designed and optimized with inheritance and experience,and the design method are the two modes with the combination of experiment and numerical simulation.In the miniaturization process,the combustion chamber faces the two problems of poor atomized quality and short residence time.Therefore,in this paper,fuel premixing and combustion process of the micro-combustor are studied from the two aspects of fuel atomization and evaporation.The research includes:1.In this paper,at first,the heat and mass transfer phenomena of single droplet’s unsteady evaporation in the convective environment is analyzed theoretically through the programming solution of droplet’s governing equation.According to the existing experimental data,several heat and mass transfer correlation are tested.A mass transfer correlation which can reflect that the moving droplets evaporation under the high temperature and convection conditions is fitted based on the relative thickness of the vapor layer on the surface of the droplet.What’s more,the camparisons of several correlation under different Re_d and diffusivity are carried out.2.The evaporation characteristics of the vaporizer were tested,the effect of T_a,AFR,T_w and V_a on theη_e are studied.The experimental results show that T_a and V_a are the two major factors affecting theη_e.Most of the time,Adherent film is in the state of film boiling.When the AFR is reduced to 3,the two-phase flow pattern transform from film boiling to transition boiling under which the heat exchange efficiency of the fuel and hot wall is the lowest.The EWF and wall-impingement splashing model are introduced in the vaporizer numerical simulation.The calculation results ofη_e tend to be the same as the experimental data and more accurate than original method.On this basis,the influence of aerodynamic parameters on fuel atomization is studied.3.Then,in order to study the influence of vaporizer on the combustor performance and flow characteristic,combustion performance and effect of atomization and vaporization with different configuration and distribution number of vaporizer are calculated and analyzed on the basis of MTE120 combustor.The increase of vaporizer number can improve the atomization quality,combustion performance and lean ignition limit under the low flow state.But the outlet section performance parameters are basically unchanged when S_vt/H_L decreases to 1.4.According to the requirements of MTE,the basic dimensions of the MTE171’s combustor is estimated with the empirical formula and one-dimensional calculation.There are three types of combustor with different holes arrangement are designed with the use of numerical calculation.The average of the combustion efficiency over 95%,meets the overall performance indicators.The inlet parameters of the combustion chamber under various conditions are determined by Gasturb and the change rule of the combustor performance with different inlet condition is studied.At last,optimal design on MTE171 cooling is conducted.The half-stamping hole is applied to replace the round hole,and the distribution of wall temperature at design point is obviously improved.When the distribution parameters Z/ns of the film holes are less than 0.55,the cooling efficiency will be over 70%.