共查询到15条相似文献,搜索用时 140 毫秒
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针对柴油机二,四气门进气系统的特点,通过稳流气道试验测量了二气门和四气门的螺旋气道,切向气道及组合气道的流动特性,讨论了不同组合的进气道和缸内气体流动的特点,提出了评价组合气道流动特性指标的方法。 相似文献
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进气道布置对4气门柴油机进气门口三维流场的影响 总被引:1,自引:1,他引:0
在稳流模拟试验台上,利用自行研制的单独进气道,4气门柴油机试验缸盖,气门口三维流速测量装置,用热线风速仪测量了不同进气道布置方案下的进气门口三维流场,揭示了进气道的布置对4气门柴油机进气门口三维流场影响的变化规律。进气道布置角度的变化对4气门柴油机各气道气门口流场产生较大影响,螺旋气道布置角度的变化使螺旋气道的各速度大小,切向速度的分布及切向气道的各速度大小发生较大变化。且升程愈大,变化愈明显,切向气道布置角度的变化对螺旋气道和切向气道的速度大小影响均较大。 相似文献
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介绍了直喷式柴油机的4气门进气系统。通过进行螺旋气道与变截面切向气道的组合试验,分析了不同流通截面等因素对气缸内涡流的影响。用热线风速仪测量缸内空气运动。讨论了2个进气道和气缸内的流动规律,探讨了最佳涡流效果的4气门进气系统的设计原则,提出了评价指标和方法。 相似文献
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进气道的布置对四气门柴油机气缸内涡流影响的变化规律 总被引:1,自引:0,他引:1
利用测得的四气门柴油机气门口三维流场,分析了进气出口流场产生的气缸内空气动量矩流率,揭示了进气道的布置对四气门柴油机缸内空气动量矩流率影响的变化规律。两进气道布置角度的变化对四气门柴油机缸内空气动量矩流率产生较大影响。螺旋气道布置角度的变化对各气道切向速度绕自身气门轴线及径向速度绕气缸轴线的动量矩流率产生较大影响,且升程愈大,变化愈明显;切向气道布置角度的变化对螺旋气道切向速度绕自身气门轴线的动量矩流率影响较大,对切向气道小升程时的径向速度绕气缸轴线的动矩流率及中、大升程时的切向速度绕自身气门轴线的动量矩流率影响较大。 相似文献
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This paper investigates the effect of intake port configuration on the swirl that is generated within a direct injec- tion (D.I.) diesel engine. The in-cylinder flow characteristics are known to have significant effects on fuel-air mixing, combustion, and emissions. To clarify how to intensify the swirl flow, a swirl control valve (SCV) and a bypass were selected as design parameters for enhancing the swirl flow. The optimal intake port shape was also chosen as a parameter needed to efficiently generate a high swirl ratio. The results revealed that a key factor in generating a high swirl ratio was to control the intake airflow direction passing through the intake valve seat. Further, the swirl intensity was influenced by changing the distance between the helical and tangential ports, and the swirl flow was changed by the presence of a bypass near the intake valve seat. Additionally, the effect of in- take port geometry on the in-cylinder flow field was investigated by using a laser sheet visualization method. The experimental results showed a correlation of swirl ratio and mass flow rate. In addition, we found that employing the bypass was an effective method to increase swirl ratio without sacrificing mass flow rate. 相似文献
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The effects of in-cylinder EGR stratification on combustion and emission characteristics are investigated in a single cylinder direct injection diesel engine. To achieve in-cylinder EGR stratification, external EGR rates of two intake ports are varied by supplying EGR asymmetrically using a separated intake runner. The EGR stratification pattern is improved using a 2-step bowl piston and an offset chamfer at the tangential intake port. When high EGR gas is supplied to the left (tangential) port, a high EGR region is formed at the central upper region of the combustion chamber. Consequently, combustion is initiated in the low EGR region, and PM is reduced significantly. When high EGR gas is supplied to the right (helical) port, a high EGR region is formed at the lower periphery of the combustion chamber. Therefore, combustion is initiated in the high EGR region, and NOx is reduced without PM penalty. Stratified EGR potentially reduces NOx by maximum 45%, without penalties of performance and other emissions. A proper in-cylinder swirl with stratified EGR maximizes the effects and achieves simultaneous reduction of NOx by 7% and PM by 23%. Moreover, the robustness of stratified EGR is evaluated under various operating conditions and injection strategies. 相似文献