Abstract:To study the emissions performance of the “Combustion Chamber with a Higher and a Lower Reentrant Swirl Chamber”(hereafter called CCHL)in high altitude areas , AVL Fire was applied to switch CCHL to some diesel engine to simulate the combustion at altitude of 4500 meters. The results indicate that CCHL can produce less emissions of NOx and SOOT simultaneously than the original combustion chamber . In order to further optimize CCHL's emissions performance in high altitude areas, different depth-diameter ratios, different High-low swirl chamber's radius ratios and different Nozzle hole cone angels was set to simulate the combustion. And the results shows that, within the range of calculation, with the maximums of depth-diameter ratios increasing, NOx emissions went down first but then it went up, as SOOT emissions went up first but then it went down. Besides, with the maximums of High-low swirl chamber's radius ratio, NOx emissions went down first but then it went up, while the SOOT emissions has fallen. Furthermore, with the increasing of Nozzle hole cone angel, the NOx emissions went down first and then it went up but then it went down again, and finally went up, maintain a “w” trend, while the SOOT emissions first went up but then it went down. It provides a reference for the CCHL used in high altitude areas.