Diesel Exploration And Study Of The Vortex Nozzle

The formation of fuel mixture plays an important role on the performance in diesel engine. On the other hand, the fuel's atomizing characteristics decide the quality of the fuel mixture directly, and furthermore, the combustion processing and engine's performance. On the direct-injection diesel engine used in cars currently, lots of effective methods, for example, high-pressure spray and pre-introduction spray, are taken to improve the atomization, but some problems, such as a spray with a fuel-fulfilled core, and the fuel's contact with the wall in cylinder, still exist.Recently, the application of the swirl-atomizer in other fields has showed that ,with the penetration distance reduced obviously, the swirl-atomizer's spraying performance is better than hole atomizer's, so in this research, the attempt to apply swirl-atomizer in diesel engine was carried on, and its feasibility was testified.In this research, a basic study about the possibility of hollow cone spray and the influencing factors, on swirl-atomizer used in diesel engine, was carried on in theory by CFD (computed fluid dynamics).Because particularity of this research, the Euler-Lagrange method applied widely in simulating computation of diesel engine is not a proper choice. The computing models used frequently in current were analyzed in this research, and the more proper simulating method was chosen according to the research goal.In research processing, the influences caused by lots of factors, such as the diameter and length of spraying outlet, the shape (square or cone) of swirling body, internal and outer chafer or not, needle valve or not, needle valve with bump or not, injection pressure and ambient pressure, on the spraying characteristics such as penetrating distance, spraying angle, velocity field, and pressure field, were studied.From the simulating results, it is found that for diesel fuel it is hard to diffuse and form hollow cone because of its viscosity and the ambience it's in. But on the other hand , it is found that when the swirl momentum reaches some magnitude on a well-designed atomizer under special spraying condition, for diesel fuel it is realizable to form hollow cone.At last, advantages and disadvantages in this research were summarized, and further improvements in the following work were pointed out.