涡流特性对汽油机燃烧压力循环变动的影响

Effect of In-Cylinder Swirl Characteristics on Cyclic Variation of Combustion Pressure in Gasoline Engine

利用所研制的四气门汽油机可变斜轴涡流系统,在稳流气道试验台上研究了该系统产生的涡流特性,并在发动机试验台上利用CB-466燃烧分析仪研究了涡流特性对缸内燃烧压力循环变动的影响.研究结果表明,低转速时,平均指示压力循环变动率随涡流比的增加逐渐减小,涡流比为0.43时的平均指示压力循环变动率最小,与涡流比为0.26时的平均指示压力循环变动率相比减小了8.2%.中等转速时,平均指示压力循环变动率随涡流比的增加而逐渐增加,当涡流比达到0.39时,平均指示压力循环变动率最大,与涡流比为0.26时的平均指示压力循环变动率相比增加了20.5%.低负荷时,平均指示压力循环变动率随涡流比的增加变化较为显著,但随着负荷的增加,变化的幅度逐渐减小.

The variable inclined swirl system of a four-valve gasoline engine was developed. The inclined swirl characteristics of the system were measured on a steady flow rig, and the effects of the inclined swirl characteristics on the cyclic variation of combustion pressure were analyzed with the CB-466 combustion analyzer on the engine test-bed. The results show that the coefficient of cyclic variation of the indicated mean effective pressure decreased with the increase of swirl ratio at low speed, and it reached minimum value when the swirl ratio was 0.43, which is 8.2% smaller than that when the swirl ratio was 0.26. The coefficient of cyclic variation of the indicated mean effective pressure increased with the increase of swirl ratio at medium speed, and reacheded the maximum value when the swirl ratio was 0.39, which is 20.5% higher than that when the swirl ratio was 0.26. When the torque was low, the cofficient of cyclic variation of the indicated mean effective pressure varied more greatly with the swirl ratio compared with the high-torque condition.