| Impinging streams with continuous gas phase have significant strengthening effect on the combustion process of atomized liquid fuel.However,due to its complexity,the strengthening mechanism of impinging streams on spray combustion process has not been studied as a scientific issue.This paper has carried on the theoretical analysis and experimental research to the key influence factors and their influence rule in the spray impinging combustion process.The spray impinging combustion experiment platform has been designed and built.Experiments were respectively conducted for conventional spray and counterflow spray combustion.Then more experiments are conducted by varying fuel type,gas velocity,air/fuel ratio,nozzle structure,nozzle spacing,nozzle angle and other parameters,after analyzing the flame structure morphology and temperature variation and distribution characteristics respectively,some key influence factors and their Influence rule are obtained.The conclusions are as follows:The common effects of impinging streams on conventional spray and counterflow spray combustion include:(1)The impact of impinging streams on the spray combustion with gasoline and diesel fuel is greater than that with alcohol fuel.(2)The larger the gas velocity is,the more significant the strengthening effect is.The combustion efficiency and the temperature of the impinging flame zone rise first and then stabilize.However,the excessive gas velocity can cause flame instability.(3)The influence of the nozzle structure is similar to that of the gas velocity.The smaller the injection hole diameter is,the greater the gas velocity is,the temperature and the combustion efficiency of impinging flame zone first increase and then stabilize,but the smaller diameter can cause the flame range and stability to decrease.(4)As the nozzle spacing decreases,the range of the impinging flame zone expands,the temperature and combustion efficiency of the impinging flame zone increase first and then decrease.However,too small nozzle spacing can cause the flame stability to decrease.Besides,for conventional spray combustion:(1)When consuming the sameamount of fuel,the opposed nozzle impinging flame is more stable,the flame temperature and combustion efficiency is higher,and the distribution is more continuous.(2)Keeping the air flow constant,with the increase of the fuel flow rate,the air/fuel ratio decreases,the temperature of the impinging flame zone of the conventional spray impingement combustion first increases and then stabilizes.The combustion efficiency increases first and then decrease.(3)The closer the nozzle angle is to 180°,the higher the overall flame temperature is and the more uniform the distribution is,the more stable the impinging flame zone is,and the higher the combustion efficiency is.For counterflow spray combustion:(1)The larger the pressure difference between the oxidant side and the fuel spray side is,the more significant the strengthening effect is,but the excessive pressure difference will cause flame instability.(2)Keeping the air flow constant,with the increase of the fuel flow rate,the air/fuel ratio decreases,the temperature of the impinging flame zone and combustion efficiency increase first and then decreases. |
