جستجوی مقالات مرتبط با کلیدواژه « diesel engines » در نشریات گروه « مکانیک »

The usage of turbochargers in diesel engines has led to the downsizing of the motors as well as usage of the waste gates in turbochargers. Any dimensional reduction in turbochargers and appurtenant leads to an enhancement on the performance of internal combustion engines and in environmental problems in terms of aerodynamic, thermodynamic and mechanical specifications for both engines and turbochargers. For this reason, the efforts need to be focused on the design of turbochargers and their waste gates accurately, in order to maintain its benefits as much as possible. The extent of waste gate opening, from full opened to closed valve, is demonstrated by the limiting compressor boost pressure ratio. Ultimately, an optimum point of limiting compressor boost pressure ratio is obtained then an increase in the values of BMEP and engine power for the same fuel consumption in range of waste gate opening is achieved

One of the most important problems in reducing the emissions of diesel engines is to exchange between the oxides of nitrogen and soot emissions. Fuel multiple injection and air injection into combustion chamber are among the most powerful tools to concurrent reduction of these two emissions. In this research, the effect of multiple injection and air injection on combustion and emission parameters has been studied by AVL fire computational fluid dynamic software. Six states of base and modified combustion chamber have been studied in two different injection patterns including 90 (25) 10 and 75 (25) 25 mods. Results show that concurrent applying of both multiple injection and air injection methods has resulted in simultaneous reduction of oxide nitrogen and soot pollutants and a negligible loss is seen in the operational parameters of engine. Compression between six studied cases show that the 90 (25) 10 mode of injection with modified combustion chamber is the optimum mode by decreasing of soot and oxides of nitrogen emissions about 29% and 20% respectively and 6% indicated power loss in compression to the base combustion chamber and single injection mode. The obtained results from the computational fluid dynamic code have been compared with the existing results in the technical literature and show acceptable behavior.