共查询到17条相似文献,搜索用时 51 毫秒
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为了分析高原环境下柴油机缸内热流分布变化规律,采用计算流体动力学方法对不同海拔高度条件下的柴油机燃烧过程进行了三维数值模拟研究。结果表明:考虑燃气向缸壁传热的燃烧过程计算时,壁面函数采用Han-Reitz模型可以得到满意结果;随着海拔高度升高,过量空气系数降低,滞燃期延长,着火推迟,燃烧恶化,爆压降低,燃烧温度升高;海拔高度越高,喷雾贯穿动量越大,壁面换热系数增长速度越快,在上止点后气体流动性对换热系数的影响所占比重增大,而进气流量对换热系数的影响比重降低,换热系数随着海拔高度升高而增大;在换热系数、壁面燃气温度和壁面油膜燃烧影响下,高海拔燃烧时壁面平均热流大幅度增大,海拔高度从1 000 m升高到4 500 m 后,缸盖和活塞瞬时平均热流最大值增幅分别达到30%和26%. 相似文献
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本文叙述了一个用于柴油机循环模拟研究的瞬态传热模型。其中缸内对流传热采用了紊流模型;辐射传热考虑了绝热火焰温度和平均气体温度的影响;燃烧室壁热传导采用了周期性瞬态热传导模型。该模型与柴油机热力循环模型相耦合,用于预测柴油机的周期性瞬态传热过程,包括瞬态对流传热系数、瞬态对流和辐射传热率以及燃烧室表面的温度波动现象。文中还介绍了该模型的应用情况。 相似文献
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试验台的结构对B/FL413F风冷柴油机扭振特性的影响 总被引:1,自引:0,他引:1
该文分析了不同联接方案的试验台对BF12L413F及BF8L413F风冷柴油机扭振特性的影响。对装甲车用V型机激振力矩的合成方法进行了论述,并说明了BF8L413F激振力矩合成的特点。 相似文献
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4气门柴油机缸内涡流形成的试验研究 总被引:1,自引:0,他引:1
在稳流气道试验台上,利用热线风速仪对4气门柴油机缸内流场进行了测量,研究了该柴油机缸内进气涡流的形成过程,揭示了进气过程气体流动的特点和规律,并从湍流的角度分析了缸内气流的发展与衍变.研究结果表明,在气缸盖出口流场,气流变化较强烈,湍流强度高,难以形成明显的刚性涡流;沿着气缸向下,由于湍流的作用使缸内流场不断衰减并均匀化,在较远处形成稳定的涡流. 相似文献
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Experimental Investigation on Space-dispersed Double-wall Jet Combustion System for DI Diesel Engine
A space-dispersed double-wall jet combustion system was developed by adopting the wall-guiding spray method and the stratification theory.The experimental test was carried out to optimize the structural parameters of the diesel-engine combustion system,including chamber structure,swirl ratio of cylinder head,included angle of jet orifice,number and diameter of jet orifice,fuel injection pressure and timing.The effect of double-wall jet combustion system on combustion and engine performance was tested to obtain the best performance indexes,and the double-wall jet combustion system was compared to the prototype.The results show that NOx is reduced from 712 PPm to 487 PPm at 2 100 r/min,and from 593 PPm to 369 PPm at 3 000 r/min,which are reduced by 31.6% and 37.7%,respectively.The smoke intensity was reduced form 3.67 BSU to 2.1 BSU,and the oil consumption was reduced from 240.5 g/(kW·h) to 225.4 g/(kW·h),which was decreased by 6.3% at low speed.The pressure in the cylinder was obviously reduced from 115 bar to 108 bar,which was reduced by 6%. 相似文献
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本文对150单缸隔热柴油机活塞热负荷进行了研究,以实测温度为边界条件,用二维平面、轴对称平面温度场专用计算程序,对隔热前后活塞温度场和热流作了计算,绘制出等温线图和热流图。研究表明,燃烧室表面喷涂陶瓷隔热层后,减少了高温气体向燃烧室壁的传热量,改善了活塞热负荷。 相似文献
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The variation of the curve of the no-load deceleration process of the diesel engine is affected by the lubricatingoil temperature. To improve the evaluating accuracy of the diesel engine technical condition by using no-load deceleration process, the investigation on the deceleration process curve under various lubricating-oil temperatures of a special-type vehicular diesel engine is conducted and the no-load deceleration curve tested under various lubricating-oil temperatures is normalized. The normalized calculation method is searched. As a result, the repeatability of the no-load deceleration curve is improved and the absolute time error of no-load deceleration under various lubricating oil temperatures is reduced. 相似文献
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