共查询到17条相似文献,搜索用时 375 毫秒
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应用数值方法对设计的车用燃气轮机的轴流涡轮结构及性能影响作了分析,研究位置分别为叶尖、叶中、叶根。计算结果表明:轴流涡轮是在亚音速流场内工作,没有激波产生,也没有不合理的流动现象和很大的流动损失,它能较好地运转在工况点上。 相似文献
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本文给出了一个110mm的径流式涡轮增压器涡轮叶轮内部的激光测速仪的测量结果。在宽广的流动状态下,采用激光测速仪对转子上游、内部和下游若干截面上的气流速度即流动角进行了测试。 相似文献
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6.废气涡轮增压器的结构如何?
图12-7所示为径流式涡轮增压器的结构图。废气涡轮增压器由压气机、涡轮及中间壳体组成。压气机部分由压气机叶轮2、压气机壳3和扩压器4等组成单级离心式压气机:涡轮机部分由涡轮壳12、涡轮和叶轮15、喷嘴环18和涡轮端盖板17等组成单级径流式涡轮机。压气机叶轮2与涡轮机叶轮15装在同一根轴上构成转子组.并支承中间支承体两端的浮动轴承21上。中间支承体左端装有压气机壳3.右端装有涡轮壳12。 相似文献
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本文分析了径流式涡轮不同进口型线(前弯、径向及后弯)叶轮进口段展的二元势波特性,揭示了叶轮进口型线对其内流特性以及涡轮级性能的影响,由此还得到了一系列可供设计参考的分析结果。 相似文献
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涡轮复合技术中脉冲排气对两级涡轮性能产生显著影响。为探明脉冲来流下两级涡轮非定常特性,该文基于三维非定常流动仿真模型研究了排气脉冲频率与幅度的影响。模型中,高压级涡轮内流动采用全通道模拟以考虑蜗壳引起的非对称流动,低压级涡轮内流动采用单通道模拟以提高计算效率。结果表明,当脉冲频率从40 Hz增加到120 Hz,高压级涡轮瞬时功率峰值显著增大15.4%,而低压级涡轮瞬时功率峰值变化在1%以内;随脉冲幅度增大,低压级涡轮效率下降幅度比高压级涡轮更大,当脉冲幅度系数为1.6时,高、低压级涡轮转子效率分别下降3.66%和8.09%;低压级涡轮转子从叶中到叶尖处的进口流动攻角在脉冲周期内大幅度变化,引起叶片前缘处产生显著流动损失。 相似文献
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涡轮增压器轴向力稳态数值模拟及优化 总被引:1,自引:0,他引:1
采用Numeca数值分析软件建立了某增压器涡轮机及压气机端流场网格模型,并计算出发动机不同转速下涡轮增压器的涡轮端及压气机端的稳态轴向力分布,分析得出由涡轮端指向压气机端方向的轴向力值较大,而由压气机端指向涡轮端方向的轴向力值较小。对压气机叶轮流场进行了分析,发现压气机叶轮背部间隙内的静压分布与轴向力大小紧密相关;研究了叶轮叶顶间隙对轴向力的影响,发现叶轮轴向间隙对轴向力的影响比径向间隙大,但效率损失亦较大。在保证涡轮机效率不降低的原则下,对涡轮箱流道截面进行了改进,轴向力在发动机高转速下降低约8N。 相似文献
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车用涡轮增压器蜗壳内三维流场模拟分析 总被引:1,自引:1,他引:0
建立了盖瑞特TB25型涡轮增压器蜗壳内部流道几何模型,并使用三维CFD软件AVL Fire对此模型的可压缩、粘性三维流场进行了数值模拟。分析表明,在进气蜗壳的拐角处速度有明显的降低,且局部产生旋涡。对此处进行了修改,并重新分析了涡轮内部的流动情况。结果是,该处的速度等值线分布均匀,没有出现速度明显降低的情况,且较之修改前总-静效率提高了0.12%。 相似文献
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Y. L. Qi L. C. Dong H. Liu P. V. Puzinauskas K. C. Midkiff 《International Journal of Automotive Technology》2012,13(6):861-872
It is well known that in-cylinder flow is very important factor for the performance of SI engine. An appropriate in-cylinder flow pattern can enhance the turbulence intensity at spark time, therefore increasing the stability of combustion, reducing emission and improving fuel economy. In this paper, the effect of intake port design on in-cylinder flow is studied. It is found a vortex existed at the upper side of intake port of a production SI engine used in the study, during the intake stroke, which will reduce both tumble ratio and volumetric efficiency. A minor modification on intake port is made to eliminate the vortex and increase tumble ratio while keeping volumetric efficiency at the same level. It is demonstrated that the increase in tumble in the new design results in a 20 per cent increase in the fuel vaporization. In this study, both KIVA and STAR-CD are used to simulate the engine cold flow, as well as ICEM CFD and es-ice used as pre-processor respectively due to the complexity of engine geometry. Simulation results from KIVA and STAR-CD are compared and analyzed. 相似文献
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采用Numeca数值分析软件分析了3种不同出口结构形式的压气机叶轮性能,等出口大径情况下径流叶轮压比最高,斜流叶轮压比最低,效率方面则是半斜流叶轮最高。通过压气机流场分析发现,各转速小流量下,径流叶轮在叶轮出口轮缘一侧产生大范围的回流,斜流叶轮则在轮毂一侧产生较大范围的回流,而半斜流叶轮兼有径流叶轮和斜流叶轮设计特点,轮毂和轮缘两侧的流场均得到明显改善。在堵塞流量附近工况点,半斜流叶轮和斜流叶轮出口相对马赫数较径流叶轮略小,利于堵塞流量的增加。通过轴向载荷分析发现,由于斜流叶轮和半斜流叶轮相比等直径的径流叶轮压比较低,导致由压气机轮背指向压气机进口的轴向力减小,使得整个增压器转轴有向涡端运动的趋势,由此容易导致止推轴承压端磨损严重;与此同时,转轴移动也会使得叶轮与压气机蜗壳的轴向间隙增大,导致半斜流叶轮与斜流叶轮效率降低。 相似文献
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为研究导流板位置对蜗壳除尘器内流场和粉尘粒径的影响,以指导回收粉在沥青搅拌设备中的实际使用,在导流板3种不同位置工况下,对蜗壳除尘器内部气相和气固两相流动状态进行了数值模拟和试验验证。数值模拟基于FLUENT软件,其中气相流场模拟选用雷诺应力模型,气固两相流场模拟选择相间耦合的随机轨道模型模拟粉尘的运动轨迹,分别追踪了16 400个粒径在50~1 000 μm的粉尘,计算了除尘效率。在沥青搅拌设备工地分别采集了导流板3种位置工况下的回收粉,结合筛分和电镜扫描试验,分析粉尘粒径分布,并对数值模拟结果的吻合性进行验证。结果表明:导流板处于O位时,除尘器内部气流的径向速度、轴向速度和静压分布轴对称性较W位和M位好,可有效抑制非对称性扰流及夹带涡流,并削弱涡核摆动现象;导流板处于不同位置时,通过与粉尘颗粒的碰撞反弹来改变粉尘的运动轨迹,进而影响除尘器对不同粒径粉尘的除尘效率,且当导流板处于O位时更有利于对粒径大于100 μm的粉尘的回收。导流板处于O位时,试验测量的粉尘平均粒径为117.6 μm,筛底平均粒径为49.9 μm,均大于W位和M位的粒径,且与数值模拟的结论相吻合。沥青搅拌设备在实际生产过程中,应优先选择导流板O位布置,并根据回收粉粒径的需要进行实时调整。 相似文献
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Variable valve timing (VVT) and cylinder deactivation (CDA) are promising methods in reducing fuel consumption and emission at part load in SI engines. An SI engine which uses electromagnetic valvetrain (EMV) will eliminate flow restriction from the throttle valve and produce higher indicated mean efficiency pressure (IMEP) due to the disabling of some of the working cylinders at part load. Therefore, pumping loss can be significantly reduced at part-load conditions. In addition, duration and timing of valve events are variably controlled at different operating conditions. This contributes to the improvement of engine efficiency. In this study, a dynamic model of an unthrottled SI engine has been developed to simulate the engine cycle. The model uses an EMV system that allows valvetrain control and cylinder deactivation techniques to be carried out in simulation flexibly. The simulated results find the optimal valve timing for different engine speeds. The optimal timing of intake valve closing depends on engine speed linearly, while the intake valve opening insignificantly influences engine performance. Additionally, this study also shows that cylinder deactivation modes can be successfully applied in improving engine efficiency at different engine loads. Different cylinder deactivation strategies have been applied for the full range of engine loads. It is concluded that the two-cylinder deactivation mode (50% CDA) considerably improves fuel consumption at low engine load. Meanwhile, one-cylinder deactivation (25% CDA) is an optimal fuel economy mode at medium engine load. With proper uses of VVT and CDA strategies, the efficiency of an SI engine can be increased more than 30% at low engine load and 11.7 % at medium engine load. 相似文献