Study Of The Injection And Interaction Process Of Natural Gas/Diesel Dual Fuel Based On Coaxial Injection Technology

In recent years,with the expansion of industrial consumption and individual consumption,energy and environmental crisis is increasingly serious.To this end,some countries have introduced more stringent emission regulations,and the clean and efficient vehicle alternative fuels gradually become the focus of the engine industry,and natural gas resources is one of the most potential alternative energy.Some studies have shown that the traditional natural gas engine,due to the use of low-pressure injection into the air intake mode,with lack of dynamic performance,throttle loss and other defects.While the technology of high pressure direct injection technology(HPID)can effectively avoid the defects of mentioned above.Its power performance is comparable with the diesel engine,its economic performance and emissions performance will also be greatly improved.For the dual-fuel engine of using this technology,the mixing process of this two kinds of fuel and air in engine has an important impact on the combustion.In this paper,a dual-fuel injection combiner is designed to realize the injection mixing of nature gas and diesel fuel.Based on this,a visual test system is designed and built.The experimental study on the mixing process of dual fuel jet was carried out by using high-speed schlieren method.The effects of ambient pressure,natural gas injection pressure and ignition diesel temperature on the mixing process of dual fuel jet are studied in detail.The experimental results are processed by image processing software,and the characteristic parameters of the jet structure are extracted.Finally,the data are processed and analyzed.The results show that increasing the ambient pressure and jet pressure of the environment can increase the time and range of natural gas and diesel jet interactions and promote the mixing of dual fuels.And the greater the ambint pressure,the jet penetration distance becomes smaller and the cone angle of the jet increases.The higher the gas injection pressure,the greater the penetration distance and the cone angle of the jet.By comparing the characteristics of single gas jet and the gas jet in dual fuel,it is found that the effect of diesel jet on gas jet is mainly manifested in two aspects: one is momentum transmission,promotes its axial development;the other is the side take-up action,promotes its Radial diffusion.The effect of diesel temperature on the dual fuel jet is also significant,and this effect mainly in the rate of evaporation of the diesel jet,and then determine the penetration and cone angle of the spry,indirectly affect the development of dual fuel jet.With the increase of the fuel temperature,the gas jet penetration increases and the cone angle gradually decreases.The current study of this paper are mainly towards the basic research of dual fuel jet mixing,which has certain reference value for the further development and design of natural gas engine.