共查询到18条相似文献,搜索用时 156 毫秒
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可视化技术能够直观地提供缸内混合气形成的信息,相比其他试验手段有无可替代的优势.本文通过对各种不同的可视化技术在发动机混合气形成过程应用的分析,总结出各种方法特点及适用范围,从而对应用可视化技术研究发动机混合气形成过程起到一定的帮助作用. 相似文献
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通过可视化手段研究缸内混合气的形成,对发动机燃烧和排放的研究有着重要的借鉴意义。本文为一台可视化缸内直喷气体机开发了高压燃气喷射系统,系统包括传感器、上位机软件、下位机喷射控制板及燃气喷射阀等部分。开发了喷射控制板的硬件电路及软件程序,并通过试验对燃气喷射阀的控制进行了优化。在可视化发动机上进行试验研究,研究结果表明开发的系统满足研究需要。 相似文献
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建立了带进排气道的缸内直喷(GDI)汽油机三维数值模型,并对喷雾模型和燃烧模型进行了实验标定,进而模拟了GDI发动机化学当量比条件下均质混合气和分层混合气两种模式从进气-喷雾-混合气形成-燃烧的全过程.模拟结果表明,GDI发动机高压多孔喷嘴喷雾雾化明显,贯穿距离较长,进气过程中缸内形成强滚流促进燃油蒸发和油气混合;进气冲程单次喷射可在缸内点火之前形成较为均匀的混合气,进气和压缩冲程中进行两次喷射可在缸内点火之前形成火花塞附近较浓、周围较稀的分层混合气;在化学当量比条件下适当采用分层混合气燃烧,与均质混合气相比可以降低燃烧速度,从而减小最大爆发压力和压力升高率.计算结果有助于深入理解GDI发动机的工作过程,并为后续研究GDI燃烧控制策略提供了模拟计算平台. 相似文献
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对一种新型柴油机喷嘴进行了可视化试验与模拟计算.应用三维CFD(Computational Fluid Dynamic)软件模拟了两种喷雾形式下不同喷油参数对柴油机混合气形成、燃烧及排放的影响,得到了最佳的喷油策略.结果表明,相对于复合喷雾,伞形喷雾在混合气形成方面存在一定的优势,对燃烧和排放有较大改善;混和气形成较好,燃烧效率高,指示油耗较低,碳烟二次氧化迅速.并且伞形喷雾中,采用小的索特平均直径,高的喷射速度,能够使发动机性能得到较大地改善. 相似文献
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《小型内燃机与摩托车》1976,(2)
活塞式煤气机的工作混合气用高压电火花点火,而高压电火花则由各种高压点火系统获得。点火系统应能保证工作混合气在发动机的各种工况和各种运转条件下可靠的燃烧。活塞式煤气机在工作的条件下,工作混合气在活塞向上死点移动的压缩行程点火。这是因为煤气-空气混合气的燃烧过程不是瞬时过程,而是持续一定的时间(几毫秒)。 相似文献
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《小型内燃机与摩托车》1997,(1)
为控制混合气形成,开发了一台混合气喷射汽油机。这台发动机在气缸盖上具有一个小的混合室和驱动混合气喷射阀的机构。利用荧光技术获得液相和气相燃料的分布状态,通过影象处理技术计算出缸内流场的图象,从进气行程到压缩行程,混合气都喷射到涡流中心,并且在压缩行程的末端靠近火花塞处形成高浓度的燃料蒸气区域。混合气形成层状分布对稀混合气燃烧的稳定性是有效的,已证明该机稀燃极限可高达40。 相似文献
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两种燃烧室混合气形成过程 总被引:1,自引:0,他引:1
本文用油-油喷射模拟方法,研究了C_5型和B 型燃烧室的混合气形成过程,说明了喷注夹角及其它因素对混合气形成方式的影响。给出了C_5和B 型两种燃烧系统的物理模型。模拟试验结论对发动机试验结果作出了合理解释。 相似文献
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HCCI (Homogeneous Charge Compression Ignition) has been touted for many years as the alternate technology of choice for future engines, preserving the inherent efficiency of CIDI (Compression Ignition Direct Injection) engines while significantly reducing emissions. The current direction for all published diesel HCCI research is mixture preparation using the direct injection – system, referred to as internal mixture formation. The benefit of internal mixture formation is that it utilizes an already available direct injection system. Direct injected diesel HCCI can be divided into two areas, early injection (early in the compression stroke) and late injection (usually after Top Dead Center (aTDC)). Early direct injection HCCI requires carefully designed fuel injector to minimize the fuel wall-wetting that can cause combustion inefficiency and oil dilution. Late direct injection HCCI requires a long ignition delay and rapid mixing rate to achieve the homogeneous mixture. The ignition delay is extended by retarding the injection timing and rapid mixing rate was achieved by combining high swirl with toroidal combustion-bowl geometry. There is a compromise between Direct Injection (DI) and HCCI combustion regimes. Even under ideal conditions, it can prove difficult to form a truly homogeneous charge, which leads to elevated emissions when compared to true homogenous charge combustion and also strongly contribute to the high sensitivity of the combustion phasing to external parameters. The alternative to the internal mixture formation is, predictably, external mixture formation. By introducing the fuel external to the combustion chamber one can use the turbulence intake process to create a homogeneous charge regardless of engine conditions. This eliminates the need for combustion system changes which were necessary for the internal mixture formation method. With this method, the combustion system remains fully optimized for direct injection and also capable of running in HCCI combustion mode with nearly ideal mixture preparation. The key to the external mixture formation with diesel fuel is proper mixture preparation. 相似文献
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氢是可再生洁净能源,氢空气混合燃烧产生的唯一的有害排放物是NOx,本文从燃烧理论和化学动力学角度分析了氢喷射火花点火氢发动机中氢空气混合气的燃烧及其NOx的形成,并着重描述了低NOx燃烧。 相似文献
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Xing-hua Liu Fu-shui Liu Lei Zhou Bai-gang Sun Harold. J. Schock 《International Journal of Hydrogen Energy》2008
Hydrogen internal combustion engine (H2ICE) easily occur inlet manifold backfire and other abnormal combustion phenomena because of the low ignition energy, wide flammability range and rapid combustion speed of hydrogen. In this paper, the effect of injection timing on mixture formation in a manifold injection H2ICE was studied in various engine speed and equivalence ratio by CFD simulation. It was concluded that H2ICE of manifold injection have an limited injection end timing in order to prevent backfire in the inlet manifold. Finally, the limit of injection end timing of the H2ICE was proposed and validated by engine experiment. 相似文献
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《International Journal of Hydrogen Energy》2022,47(2):1319-1327
The authors have proposed a new combustion process called the Plume Ignition Combustion Concept (PCC), in which with an optimal combination of hydrogen injection timing and controlled jet geometry, the plume of the hydrogen jet is spark-ignited to accomplish combustion of a rich mixture. This combustion process markedly improves thermal efficiency by reducing cooling loss, which is essential for increasing thermal efficiency in a hydrogen engine while maintaining high power. In order to improve thermal efficiency and reduce NOx formation further, PCC was applied to a lean-burn regime to burn a leaner mixture globally. In this study, the effect of supercharging which was applied to recover the reduced output power due to the leaner mixture on improving thermal efficiency was confirmed along with clarifying the cause. 相似文献
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对柴油机用轴针式喷油器实现直喷燃烧的分析 总被引:1,自引:0,他引:1
从研究Elsbett“双热区”隔热直喷燃烧系统(DuothermicCombustionSystem)出发,分析了喷雾贯穿。喷孔直径、喷油器安装位置、铰接式铸铁活塞、采用机油冷却及增压等对混合气形成及燃烧过程的影响。认为,适当增加进气涡流强度、缩小喷孔与轴针之间的配合公差、采用铸铁活塞头部、以机油作为冷却介质、实现高温冷却等措施,有利于改善小缸径柴油机混合气形成及燃烧过程。“双热区”燃烧系统对采用轴针式喷嘴实现小缸径柴油机的直喷燃烧有许多值得借鉴之处。 相似文献