Experimental Investigation of the Effects of Air Injectionand Injection Timingin a Natural Aspirated DI Diesel Engine

In this experimental study, the effect of creating an air jet inside the combustion chamber by establishing an air-cell inside of the piston body at different injection timings in a DI diesel engine has been studied at 2000 rpm and full load operation. The performed tests include studying the Soot and NOx emissions, combustion and performance parameters. The obtained experimental results show that using an air-cell inside the piston causes in simultaneous reduction of Soot and NOx emissions, also advanced  injection timing results in increasing of brake power and reduction of brake specific fuel consumption(bsfc) with increasing of maximum pressure in the combustion chamber  and maximum value of heat release rate. Also, the results showed that the best time injection for air cell engine is 13 BTDC, in which the NOx and soot emissions decrease by 15% and 50%, respectively, while BSFC and power remains relatively unchanged.