Numerical Simulation Of High Altitude Light Oil Burner Based On CFD

People’s Liberation Army officers and soldiers working on the plateau have a high demand for burners for heating,cooking and other functions.However,the general burner in plain area is very difficult to adapt to the physical environment of high cold,low pressure and low oxygen in plateau area.Therefore,it is necessary to optimize the burner design for high altitude environment.This paper mainly refers to riello 40 g5 rmc,a light oil burner of Italian company liyalu,and improves the structure of plain burner and the ratio of air and fuel based on CFD,so as to apply it to the plateau environment with an altitude of about 4000 m.The main research contents are as follows:1)first,based on the pressure swirling atomization model and the spray combustion theory of the liquid,the theoretical analysis of burner ignition,flame shape,spray quality,spray cone angle and combustion temperature under high altitude environment is made,and a mathematical model suitable for the simulation calculation of burner is established.Then,the physical modeling and grid division of combustion head and furnace are carried out by using Solid Works and ICEM software.At the same time,the boundary conditions of burner and furnace as well as the calculation method of flame front position are determined for the comparison of simulation results in the following paper;the grid is verified to be irrelevant,and the complete model is verified.The optimization criteria of burner design are determined by the temperature distribution,flame shape and thermal efficiency.2)Then,the influence of three environmental conditions(air temperature,air pressure and air oxygen content)affected by altitude on the combustion state of plain type burners is calculated.It is found that the average / maximum temperature of furnace outlet increases slowly with the decrease of ambient pressure.Flame width slightly increased.The thermal efficiency increased by 12.2%;with the decrease of ambient temperature,the change of outlet temperature was not obvious,but the thermal efficiency decreased by 4.8%;with the decrease of air oxygen content,the outlet temperature decreased by about 33%,and the thermal efficiency decreased by 77.2%.3)Then,the influence of altitude on the performance of burner is calculated.It is found that the average temperature of outlet decreases by 19.2% and the maximum temperature of outlet decreases by 26.9% with the rise of altitude from 0 m to 5000 m,and the relationship is approximately linear with altitude.The combustion efficiency of furnace temperature decreased by 70.7%.4)Then,the environmental parameters at 4000 m altitude are determined,and the influence of the burner inlet parameters on the burner performance is calculated.The results show that the average / maximum temperature of furnace outlet increases slowly with the increase of air inlet temperature from 262 K to 450 k.Flame width slightly increased.Thermal efficiency increased by 12.2%;with the increase of excess air coefficient from 0.90 to 1.40,the average temperature at furnace outlet first increased and then decreased,reaching the peak level at 1.00,and the thermal efficiency reached the peak at the same time of 16.4%;with the increase of fuel atomization cone angle from 20 ° to 90 °,the average temperature at furnace outlet generally increased,and the flame shape gradually dispersed.The highest outlet temperature and thermal efficiency first increase and then decrease,and the best value is obtained at 60 °.5)Finally,the effects of two structural parameters(air inlet diameter and nozzle outlet diameter)on the performance of the burner are calculated at an altitude of 4000 m.It is found that increasing the outside diameter of air inlet from 69.46 mm to 80 mm is beneficial to the increase of combustion temperature and thermal efficiency.But this will lead to the lack of flame stability and continuity.It is more reasonable to choose the air inlet diameter of 78 mm.If the flame is not expected to be detached,72 mm can be selected as the air inlet diameter,but the thermal efficiency of 5.2% will be sacrificed;if the diameter of atomized fuel nozzle outlet is increased from 1mm to 1.6mm,the thermal efficiency of burner will be increased by 6%.The overall range has little impact.It can be seen that increasing the inlet air temperature,reducing the excess air coefficient,increasing the fuel atomization cone angle,increasing the outer diameter of the air inlet and increasing the diameter of the fuel nozzle outlet are conducive to the improvement of the burner efficiency in the plateau environment.