Numerical simulation of diesel TR combustion system

A new combustion system, named TR (three-rapidity) was developed to improve the air-fuel mixture formation in diesel engines. It was modified from ω combustion chamber with an oriented arc at the chamber wall, specially and perfectly fit in a nozzle with 4 × φ 0.36 orifices in the conic section plus 1 × φ 0.20 orifice in the center. The mixture formation process was simulated by STAR-CD. The result shows that the secondary jet formed by the oriented arc increases air entrainment and fuel-air mixture space. The fuel in jected from central orifice impinges on the plane convex at the bottom, forming discal spray, which improves the mixture in the center. TR deposited less fuel on the chamber wall and an amount of eddy with different scales and directions generated in TR chamber significantly contributed to the transient mixture formation. In the test study TR demonstrated an excellent performance with 0.1 BUS smoke emission in the part load condition and 0.4 BUS in the full load condition and retarding fuel delivery timing to 11°CA BTDC, NO_x decreases greatly. The concentration of NO_x is 203 × 10^-6-776 × 10^-6 and the smoke is 0.3-0.6 BSU in the whole load condition. It is proved that TR combustion system has great potential to improve emissions and promising the application to diesel engines.