外文翻譯--一些中速柴油發(fā)動機研究的實驗經(jīng)驗-其他專業(yè)-資料下載頁
2025-01-19 09:51本頁面
【導(dǎo)讀】進行了單缸共軌柴油機的研究,這是研究的方向。此外這個引擎沒有渦輪增壓器,但是一個單獨的空氣壓縮機供應(yīng)系統(tǒng)可以。改變進氣管空氣的狀況;在引擎后部、有一個蝶狀的改變排氣背壓的管子。這些研究進行了所有的EVE發(fā)動機可能性狀況研究:不同的負載、管道壓力,開始噴射時刻和邊界條件都是可調(diào)的。此外，該實驗對氣體交換閥門的液壓系統(tǒng)。的不同時間響應(yīng)性能進行了檢測、評價。配置最優(yōu)化基礎(chǔ)上得到的完美結(jié)果成為了一種大挑戰(zhàn)。其最大氣門升程以及它們的開啟和關(guān)閉提升斜率。閥門執(zhí)行機構(gòu)受作用于潤滑系。迄今為止,除了提到的部件的數(shù)量外，同時所有的壓力和溫度的輔助系。首要工作描述的是米勒的一個應(yīng)用技術(shù)。它是通過適時改變閥門定時減少發(fā)動機的壓縮比的。的NOx很大的降低量。來了,作用100%,75%和50%負載進行試驗。最先進的米勒計時,IVC142CADBBDC和最大進氣閥抬的毫米。o根據(jù)施加的效率改變排氣壓力以平衡模擬TC；
【正文】 the turbine. This model is needed to find the charge air pressure and the exhaust backpressure。 besides, the charge air temperature is set the same in every case. The formulas used to calculate the charge air and exhaust gas pressure are the equations of the pressor and turbine power [8]: 11 The machine efficiencies are so that the total TC efficiency is . This value is calculated from data of the previous tests and it is an average estimation of the efficiency at every load considered in this work. Furthermore, the other assumptions in the calculation model are: ?The ambient conditions: is 298 K, , is kJ/kg K, is . ?The upstream pressor pressure and the downstream turbine pressure are 1 bar。therefore and represent also the values of the charge air pressure and of the exhaust backpressure, expressed in bar. ? The pressor model is set before the intake pipe and the turbine’s model after the exhaust pipe nearby the regulating valve. The controls permit to find the engine setup to use in the test runs when the valve timing is modified. In particular: o the SOI is adjusted to match the same engine power, since the same amount of fuel is injected。 o the charge air pressure is adjusted to achieve the same air trapped mass。 o the exhaust pressure is changed to balance the simulated TC along the imposed efficiency. 12 The results of the simulations are plotted below. In particular, the intake charge air pressure, the pumping losses and the start of injection are reported. To maintain the same air mass trapped in the cylinder, the charge air pressure needs to be increased when the intake duration is reduced, . IVC is advanced. In figure 2 it can be seen that at high load its value is raised more than bar from the reference case. The Test Results Both fast and slow measurements have been taken during the tests. Here below the charts concerning the main outes of the work are illustrated. Since the EVE has 13 higher mechanical losses than a multicylinder engine [9], the results are here referred to the indicated power. The aimed NOx reduction is achieved at every tested load (figure 5). The best results e from the partial loads: in fact at 50% the reduction is g/kWh of ISNOx, which means 40% of the reference value, which is obtained with standard timing (figure 6). The high reduction achieved is due to both the use of the advanced IVC (Miller technique) and the later SOI. Along the previous tests run with EVE, the only usage of retarded SOI may imply even greater NOx reduction than the bined use of the same timing with Miller technique. On the other hand, to achieve the same output power more fuel would be required – . longer injection duration. As a consequence very high exhaust gas temperature as well as unstable bustion may result. These effects are too negative in the overall economy of the engine and, therefore, other means – . the usage of the Miller cycle have to be investigated in order to achieve outes that can be accepted also in a real application.
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