Research On Application Of Conical Spray In Swirl Chamber Diesel Engine

Energy and environmental issues have been the most important issues in the contemporary world, and focused by more and more people. It have been the working highlight of governments that saving energy and protecting environment to promote sustainable social development. Emission regulations for non-road compression ignition engines came into being. Swirl chamber diesel engine is in possession of an increasing proportion in single-cylinder diesel engines because of its low emission and cost. It has become an urgent task for researchers to develop the diesel engines with'High power Density','High Cost Performance' and'Low Emission' for 'three rural issues'.The performance of engines is closely related to the quality of air-fuel mixture formation and combustion processes. Increasing swirl intensity can improve mixture formation and increase combustion efficiency. But at the meantime it will increase the flowing loss and heat transfer loss inevitably, which will lead to deterioration of starting performance, and uncertainty of increasing in the combustion efficiency at the end. If more symmetrical mixture distribution can be got at low swirl ratio, heat transfer loss and flowing loss will be decreased and combustion efficiency will be increased. So, emission will be reduced, economy and starting performance will be improved.Combining with the characteristics of conical spray combustion system and air motion in swirl chamber, a new conical spray swirl chamber combustion system is proposed. In view of bell type swirl chamber diesel engine which is used widely in China, the following research works has been carried out in this paper:(1)The in-cylinder flow velocity and mixture distributions of BH175F1 swirl chamber engine were numerically studied with a CFD package. Results show that:the nozzle setting angle which results in more symmetrical mixture distribution in the main chamber is obtained, and improving combustion.(2) Combustion performance test was carried out on BH175F1 air-cooled swirl chamber diesel engine, which was produced by New Binhu Diesel Company, The test results shows that the performance of diesel engine is better by using bigger diameter pintle nozzle (Φ=1.5mm) than using smaller diameter pintle nozzle (Ф=1.5mm) at low load, and the result is contrary at high load. Using the conical nozzle in swirl chamber diesel engine can reduce the rate of fuel consumption by 3%-5% at part load, and NOx also was reduced obviously. (3)Projects of new conical spray swirl chamber diesel engine were designed. Numerical simulations have been conducted using a 3-D CFD code on mixture formation and combustion processes with different projects. So that new conical spray swirl chamber diesel engines with better performance were designed.