高滚流燃烧系统对小型增压汽油机性能的影响

Effects of High Tumble Combustion System on the Performance of a Compact Turbocharged Gasoline Engine

针对一款3缸增压气道喷射汽油机,采用三维仿真与台架试验相结合的方式,研究了中、高滚流比燃烧系统在外特性工况下对缸内燃烧、整机动力性、经济性的影响。结果表明:滚流比数值大小直接影响湍动能峰值出现时刻及湍动能中心位置,进而影响火焰传播及发展;过高滚流比会导致湍动能中心偏心,影响火焰传播。采用中等滚流比的燃烧系统A有利于火核形成及火焰传播,缩短总燃烧持续期,进而提高热效率。在中低转速时,中等滚流燃烧系统A燃烧50%燃料所对应的曲轴转角比高滚流燃烧系统B提前,最多可提前3.4°,指示平均压力循环波动率可维持在3%左右。

By the combination of 3D simulation and bench test, effects of medium and high tumble ratio combustion system of a three-cylinder turbocharged port-injection gasoline engine on the engine performance of combustion, power and fuel consumption were studied under full load conditions. Results show that the value of tumble ratio directly affects the moment of turbulent kinetic energy peak and the center of turbulent kinetic energy, which affects the flame development and propagation. The excessively high tumble ratio will cause the center of turbulent kinetic energy to eccentric and affect the flame propagation. The medium tumble ratio combustion system A facilitates the formation of flame core and the flame propagation, shortening the total combustion duration and improving the thermal efficiency. At low-to-medium speeds, the crank angle of 50% mass fraction burned （MBF50） by the medium tumble ratio combustion system A is 3. 4°ahead of the value of the high tumble ratio combustion system B, while the indicated mean pressure cycle variation can be maintained at 3%.