Zhang Shiwei, Shi Cheng, Di Liming
Zhengzhou Tourism College, Zhengzhou450009, China.
School of Vehicle and Energy, Yanshan University, Qinhuangdao 066004, China.
ACS Omega. 2023 Sep 22;8(39):36418-36434. doi: 10.1021/acsomega.3c05415. eCollection 2023 Oct 3.
By effective utilization of the dynamic mesh and coordinate transformation techniques, an ultrasonic horn is physically integrated in the chamber of an internal combustion engine. The consequences of multiple ultrasonic-fed strategies on the flow field, combustion process, and emission formation under the same working conditions are studied by numerical simulation. Based precisely on the bench test data, GT-Power and CONVERGE set up the original engine one-dimension (1d) and three-dimension (3d) simulation models. The chamber pressure and heat release rate of the 1d and 3d models under a full load condition of 3000 r·min were validated, and the maximum relative error is less than 5%, proving the accuracy of the model. By reforming the 3d numerical model, ultrasonics is added to the gasoline engine's combustion chamber. Six different ultrasonic-fed schemes with 20 kHz amplitude of 30-300 μm are typically selected for in-depth research. The larger the amplitude, the stronger the turbulent kinetic energy (TKE), and the maximum TKE exceeds 46.6% at the ignition time. Stronger TKE can energetically encourage the generation of OH, O, and H radicals and improve the combustion reaction rate, and the peak pressure () is increased by 1.9 MPa compared with scheme No. However, NO and HC emissions gradually increase, reaching a maximum of 32.4 and 43.8%, respectively, while CO and soot emissions decrease, reaching a maximum of 11.4 and 11%, respectively. Four groups of ultrasonic-fed schemes with an amplitude of 100 μm and frequency of 20-50 kHz are scientifically studied. The findings indicated that the TKE level steadily increases as the frequency increases and the in-cylinder TKE increases by 16.4% at ignition time. The increase in ultrasonic frequency can promote the generation of active free radicals and meaningfully improve the combustion reaction rate to a certain extent. The can be increased up to 1 MPa compared with scheme No. At the same time, the NO, HC, and soot also increased considerably, reaching 31.8, 17.9, and 21.9%, respectively. The CO showed a downward trend but gradually slowed, with a maximum decline of 6.5% at 20 kHz. The above simulation analysis is based on the full load condition of 3000 r·min, sufficiently proving that ultrasonics has a regulation effect on emissions and can achieve specific emissions through later optimization.
通过有效利用动态网格和坐标变换技术，将一个超声变幅杆物理集成到内燃机的燃烧室内。通过数值模拟研究了在相同工况下多种超声馈入策略对流场、燃烧过程和排放生成的影响。精确基于台架试验数据，GT-Power和CONVERGE建立了原始发动机的一维（1D）和三维（3D）仿真模型。对1D和3D模型在3000 r·min满负荷工况下的气缸压力和热释放率进行了验证，最大相对误差小于5%，证明了模型的准确性。通过改造3D数值模型，将超声波添加到汽油机的燃烧室内。典型地选择了六种不同的超声馈入方案，其20 kHz的振幅为30 - 300μm，用于深入研究。振幅越大，湍动能（TKE）越强，在点火时刻最大TKE超过46.6%。更强的TKE能够有力地促进OH、O和H自由基的生成，并提高燃烧反应速率，与方案一相比，峰值压力（）增加了1.9 MPa。然而，NO和HC排放逐渐增加，分别达到最大值32.4%和43.8%，而CO和碳烟排放减少，分别达到最大值11.4%和11%。科学研究了四组振幅为100μm、频率为20 - 50 kHz的超声馈入方案。研究结果表明，随着频率增加，TKE水平稳步上升，在点火时刻缸内TKE增加了16.4%。超声频率的增加能够促进活性自由基的生成，并在一定程度上有意义地提高燃烧反应速率。与方案一相比，（）可增加至1 MPa。同时，NO、HC和碳烟也大幅增加，分别达到31.8%、17.9%和21.9%。CO呈下降趋势但逐渐减缓，在20 kHz时最大降幅为6.5%。上述模拟分析基于3000 r·min的满负荷工况，充分证明了超声波对排放有调节作用，并且通过后续优化能够实现特定的排放。
