本文關(guān)鍵詞： 柴油機(jī) 配氣正時 數(shù)值模擬 KIVA-3V NOX Soot　出處：《華中科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：配氣正時直接影響著內(nèi)燃機(jī)的換氣過程優(yōu)劣,尤其是充氣效率、掃氣效率和換氣損失。換氣過程的好壞決定了缸內(nèi)燃燒品質(zhì),從而影響著發(fā)動機(jī)的動力性、經(jīng)濟(jì)性、排放水平及其可靠性。發(fā)動機(jī)處于高轉(zhuǎn)速時,一般需要設(shè)置較大的氣門重疊角及進(jìn)氣門遲閉角,減少缸內(nèi)殘余廢氣量和增加進(jìn)入氣缸的新鮮充量,提高輸出功率;發(fā)動機(jī)處于低轉(zhuǎn)速或怠速運(yùn)轉(zhuǎn)時,需要設(shè)置較小的氣門重疊角及進(jìn)氣門遲閉角,以獲得較好的怠速穩(wěn)定性�？紤]到要兼顧高低轉(zhuǎn)速時發(fā)動機(jī)的性能,就要選擇一種折衷的配氣正時方案,使得發(fā)動機(jī)的整體性能水平發(fā)揮到最佳。本文利用GT-Power軟件建立某9.5L增壓中冷柴油機(jī)仿真模型,研究進(jìn)排氣門正時對發(fā)動機(jī)動力性能和燃油經(jīng)濟(jì)性的影響。計算并輸出用于KIVA-3V計算的ESC工況缸內(nèi)初始邊界條件,運(yùn)用KIVA-3V程序驗(yàn)證配氣正時優(yōu)化前后的排放水平。主要內(nèi)容及結(jié)論如下:根據(jù)配氣正時優(yōu)化范圍設(shè)計正交試驗(yàn)表格,利用已建立的9.5L柴油機(jī)仿真模型,確定對柴油機(jī)燃油消耗率影響的顯著性因子為排氣正時角EVT,并對其開展單因子7水平細(xì)化分析,最終確定最佳燃油消耗率下的配氣正時組合為進(jìn)氣正時角228.5°CA;排氣正時角127.2°CA。配氣正時優(yōu)化后,發(fā)動機(jī)工況區(qū)域(1100~1700rpm,40%~100%負(fù)荷)的燃油消耗率平均優(yōu)化1.18%,即從191.34g/kWh降到189.07g/kWh;工況區(qū)域的扭矩平均提升1.2%,即從1157.52Nm提升到1171.22Nm。通過GT-Power仿真分析不同排氣正時角對發(fā)動機(jī)動力性、燃油經(jīng)濟(jì)性和排放水平的影響。結(jié)果顯示,隨著排氣正時角的推后,發(fā)動機(jī)的性能穩(wěn)步提升,燃油經(jīng)濟(jì)性大幅改善。以1700rpm-100%負(fù)荷工況為例,排氣正時角從111°CA調(diào)整到127.2°CA時,發(fā)動機(jī)扭矩從1401.14Nm提升到1527.23Nm,提升比例為9.0%;燃油消耗率從221.661 g/kWh下降到203.36 g/kWh,下降比例為8.1%。NOX排放隨著排氣正時角的推后而升高,Soot排放則隨著排氣正時角的推后而降低。鑒于將排氣門正時從119.5°CA調(diào)整到127.2°CA時,NOX排放有所增加,本文隨后利用燃燒排放模擬精度較高的KIVA-3V程序,進(jìn)行了該發(fā)動機(jī)的燃燒排放研究。先利用發(fā)動機(jī)實(shí)驗(yàn)數(shù)據(jù),進(jìn)行了KIVA-3V程序中燃燒模型和排放模型的驗(yàn)證。隨后進(jìn)行了配氣正時優(yōu)化后發(fā)動機(jī)的燃燒和排放數(shù)值模擬及分析。模擬結(jié)果表明,配氣正時優(yōu)化前后發(fā)動機(jī)均達(dá)到了國四排放水平。這就使得本文的配氣正時優(yōu)化,不僅保證了排放水平,同時改善了發(fā)動機(jī)的動力性和燃油經(jīng)濟(jì)性。
[Abstract]:The timing of air distribution directly affects the quality of the internal combustion engine's air exchange process, especially the air filling efficiency, the scavenging efficiency and the air exchange loss. The quality of the in-cylinder combustion is determined by the quality of the air exchange process, which affects the engine's power performance. Economy, emission level and reliability. When the engine is at high speed, it is generally necessary to set a large valve overlap angle and intake valve late closing angle to reduce the residual exhaust gas in the cylinder and increase the fresh charge into the cylinder. Increasing output power; When the engine is running at low speed or idle speed, it is necessary to set small valve overlap angle and inlet valve late closing angle to obtain better idling stability. It is necessary to choose a compromise timing scheme to make the overall performance level of the engine to the best. A 9.5L turbocharged and intercooled diesel engine simulation model is established by using GT-Power software in this paper. The influence of intake valve timing on engine dynamic performance and fuel economy is studied. The initial boundary conditions in ESC operating conditions for KIVA-3V calculation are calculated and outputted. The emission level before and after timing optimization is verified by KIVA-3V program. The main contents and conclusions are as follows: the orthogonal test table is designed according to the optimal range of timing optimization. Using the established 9.5L diesel engine simulation model, the significant factor of the diesel fuel consumption rate is determined as the exhaust timing angle EVT, and the single factor 7 level refinement analysis is carried out. Finally, it is determined that the timing combination of gas distribution under the optimal fuel consumption rate is 228.5 擄CA. The exhaust timing angle is 127.2 擄CA.After the timing optimization, the average fuel consumption rate of the engine operating region is optimized by 1.18%. That is, from 191.34g / kWh to 189.07g / kWh; The average torque in the operating region is 1.2, that is, from 1157.52Nm to 1171.22Nm. The dynamic performance of the engine with different exhaust timing angles is analyzed by GT-Power simulation. The effect of fuel economy and emission level. The results show that the engine performance improves steadily with the delay of exhaust timing angle. The fuel economy was greatly improved. Taking 1700rpm-100% load condition as an example, the exhaust timing angle was adjusted from 111 擄CA to 127.2 擄CA. The engine torque was raised from 1401.14Nm to 1527.23Nm, and the lifting ratio was 9.0Nm. Fuel consumption decreased from 221.661 g / kWh to 203.36 g / kWh.Nox emissions increased with the delay of the timing angle of exhaust. The emission of Soot decreased with the delay of exhaust timing angle, whereas the emission of Soot increased when the timing of exhaust valve was adjusted from 119.5 擄CA to 127.2 擄CA. In this paper, the combustion emission of the engine is studied by using the KIVA-3V program with high accuracy of combustion emission simulation. First, the engine experimental data are used. The combustion model and emission model in the KIVA-3V program are verified. Then the combustion and emission numerical simulation and analysis of the engine after timing optimization are carried out. The simulation results show that. The engine before and after timing optimization has reached the level of four national emissions, which makes the timing optimization of this paper not only ensure the emission level, but also improve the engine power performance and fuel economy.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TK421.5

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