Study On The Effect Of Structure On Combustion Efficiency Of Solid Boron Powder Ramjet

Solid boron powder ramjet differs from boron-based propellant solid rocket ramjets,The boron powder is directly introduced into the combustion chamber by the fluidizing gas and mixed with the primary gas and the ram-air.Air intake and powder feeding structure of engine are the important factors that influence the residence time of boron particles,mixing effect and combustion performance.The numerical simulation of two-phase flow in Solid Fuel Ducted Rocket with swirl flow is carried out by the k-? RNG turbulence model,one-step eddy-dissipation combustion model and the ignition and combustion model of boron particles,which has fully considered every situation which will happen during the process of combustion.By numerical stimulation,the result is in agreement with experimental result.The ignition and combustion of boron particles and the combustion efficiency of gas combustion in combustor of Solid Fuel Ducted Rocket with different distrubtion of jets and dome length,air angle and length of combustion.Finally,the paper comes to conclusions that:1 The burning rate of boron particles in the eccentric combustion chamber is close to the zone.of the high temperature and oxygen enriched,and the combustion efficiency is low.The total combustion efficiency of the gas distribution structure is higher than that of the gas distribution chamber and the eccentric combustion chamber.2 For the combustion chambers with dome length lengths of 0.266 D,0.466 D and0.666 D,respectively.With the increase of the dome length,the combustion efficiency of gas increases.The dome length too long or too short is not conducive to the combustion efficiency of boron particles.To the highest combustion chamber efficiency,there is an optimal value of 0.466 D.3 For the combustion chambers with air angle of 30 o,45 o,60 o,respectively.With the increase of the air angle,the air injection depth increases,and the combustion efficiency of gas increases.To the highest total combustion chamber efficiency,there is an optimal value of 45 o.4 The residence time of the fuel in the combustion chamber and the combustion efficiency of each component increases increases with the length of the combustion chamber.5 To large velocity difference jets,the two jet spacing conditions of 40 mm and60mm are compared,when the jets spacing increases,the residence time of gas and boron particles increases in the combustion chamber,and the total combustion efficiency increases.On the basis of the jet spacing of 60 mm,The working conditions of three kinds of the momentum ratio that gas flow to fluidizing gas flow were studied.With the increase of the momentum ratio that gas flow to fluidizing flow,turbulence intensity between the jets increases,but velocity of flow in the combustion chamber increases,the fuel residence time decreased,gas phase combustion efficiency of the head combustion chamber increases first and then decreases,particle combustion efficiency and the total combustion efficiency increased.6 For tangential swirl combustion chamber,On the basis of the tangential angle of 20 o,The working conditions that 4 kinds of the radial distance between the jets(20mm,30 mm,40mm,50mm)were studied,with the increase of the radial distance between the jets,the combustion efficiency of the gas phase decreases first and then increases,but the total combustion efficiency increased.On the basis of the the radial distance between the jets of 50 mm,The working conditions that 6 kinds of tangential angle(0 o,5 o,10 o,15 o,20 o,25 o)were studied.For tangential swirl combustion chamber,with the increase of tangential angle,the turbulence intensity decreases,the combustion efficiency of the gas phase increases first then decreases,the combustion efficiency of boron increases,and the total combustion efficiency increases.