本文關(guān)鍵詞： 對(duì)置活塞對(duì)置氣缸發(fā)動(dòng)機(jī) 缸內(nèi)流動(dòng) 換氣過(guò)程 燃燒過(guò)程　出處：《中北大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：OPOC（對(duì)置活塞對(duì)置氣缸）發(fā)動(dòng)機(jī)是一種新型結(jié)構(gòu)的二沖程發(fā)動(dòng)機(jī)，具有結(jié)構(gòu)緊湊、效率高、功率密度大、整機(jī)平衡性好、布置方式靈活等優(yōu)點(diǎn)，擁有廣闊的應(yīng)用前景。OPOC發(fā)動(dòng)機(jī)雖然采用了直流掃氣、電控噴油、電動(dòng)增壓等技術(shù)，但作為二沖程發(fā)動(dòng)機(jī)其仍存在著換氣質(zhì)量不高、燃燒不充分等問(wèn)題。 本文在已有研究基礎(chǔ)上，詳細(xì)分析了不同氣口結(jié)構(gòu)下的缸內(nèi)流動(dòng)狀況對(duì)OPOC發(fā)動(dòng)機(jī)換氣及燃燒過(guò)程的影響。 文章首先計(jì)算了OPOC發(fā)動(dòng)機(jī)氣缸內(nèi)外兩活塞的具體運(yùn)動(dòng)規(guī)律，進(jìn)而得到了OPOC發(fā)動(dòng)機(jī)的缸內(nèi)容積以及進(jìn)排氣口流通面積的變化情況，在此基礎(chǔ)上設(shè)置合理的燃燒參數(shù)，建立了OPOC發(fā)動(dòng)機(jī)的一維工作過(guò)程仿真模型，得到了發(fā)動(dòng)機(jī)不同轉(zhuǎn)速下的進(jìn)排氣壓力、掃氣效率、缸內(nèi)壓力等參數(shù)。 基于一維仿真結(jié)果設(shè)定邊界條件，建立OPOC發(fā)動(dòng)機(jī)換氣過(guò)程的三維仿真模型，分別對(duì)3600r/min、2500r/min以及1600r/min三種轉(zhuǎn)速下的換氣過(guò)程進(jìn)行分析，對(duì)比不同轉(zhuǎn)速下的缸內(nèi)瞬態(tài)流場(chǎng)以及殘余廢氣分布的變化情況。通過(guò)分析發(fā)現(xiàn)：在原進(jìn)排氣口結(jié)構(gòu)作用下所形成的缸內(nèi)流動(dòng)形式并不合理，高速工況下掃氣質(zhì)量較差。 在原進(jìn)氣口模型5°/15°傾角的基礎(chǔ)上，分別設(shè)計(jì)了10°/20°、15°/30°、20°/40°三種不同的改進(jìn)方案，并對(duì)三種掃氣方案在不同轉(zhuǎn)速下的缸內(nèi)流動(dòng)、廢氣殘留等情況進(jìn)行了分析。為使發(fā)動(dòng)機(jī)在整個(gè)工作轉(zhuǎn)速范圍內(nèi)都能具有較高的掃氣質(zhì)量，文章最終選擇了15°/30°作為最終的優(yōu)化方案。 為進(jìn)一步研究所選定的15°/30°優(yōu)化方案對(duì)整機(jī)性能的影響，文章對(duì)15°/30°方案與原方案在3600r/min下的燃燒過(guò)程進(jìn)行了分析。為保證分析的準(zhǔn)確性，建立起了包括換氣過(guò)程與燃燒過(guò)程的發(fā)動(dòng)機(jī)整個(gè)工作過(guò)程的仿真模型。通過(guò)與原方案的燃燒過(guò)程對(duì)比分析發(fā)現(xiàn)：所選擇的最終優(yōu)化方案，缸內(nèi)流動(dòng)形式更加合理，，在一定程度上加快了燃油的蒸發(fā)與霧化，同時(shí)可燃混合氣分布更加均勻，燃燒過(guò)程更加迅速。最終通過(guò)對(duì)整個(gè)工作過(guò)程的P-V曲線計(jì)算發(fā)現(xiàn)，改進(jìn)方案的發(fā)動(dòng)機(jī)功率更大、油耗更低。
[Abstract]:OPOC engine is a new type of two-stroke engine, which has the advantages of compact structure, high efficiency, high power density, good balance and flexible arrangement. The OPOC engine has a broad application prospect. Although the OPOC engine adopts DC scavenging, electronically controlled fuel injection, electric supercharging and other technologies, but as a two-stroke engine, it still has a low air exchange quality. Insufficient combustion, etc. On the basis of the previous studies, the influence of the in-cylinder flow conditions on the air exchange and combustion process of the OPOC engine with different air orifice structures is analyzed in detail in this paper. This paper first calculates the specific motion law of the two pistons inside and outside the cylinder of OPOC engine, and then obtains the change of the cylinder volume and the flow area of the intake and exhaust port of the OPOC engine. On the basis of setting reasonable combustion parameters, the one-dimensional working process simulation model of OPOC engine is established, and the parameters such as inlet and exhaust pressure, scavenging efficiency and in-cylinder pressure are obtained. Based on the one-dimensional simulation results, a three-dimensional simulation model of the OPOC engine ventilation process was established. The air exchange process was analyzed at three rotational speeds: 2500r-min and 1600r-min. By comparing the change of transient flow field and residual exhaust gas distribution in cylinder at different speeds, it is found that the flow form in cylinder formed under the action of the original inlet and exhaust port structure is not reasonable. The scavenging quality is poor at high speed. Based on the 5 擄/ 15 擄inclination of the original inlet model, three different improvement schemes were designed for 10 擄/ 20 擄/ 15 擄/ 30 擄/ 20 擄/ 40 擄respectively. In order to make the engine have a higher scavenging quality in the whole working speed range, the flow in cylinder and the residue of exhaust gas are analyzed under different rotating speed of three kinds of scavenging schemes. Finally, 15 擄/ 30 擄is chosen as the final optimization scheme. In order to further study the effect of the selected 15 擄/ 30 擄optimization scheme on the performance of the whole machine. In this paper, the combustion process of the 15 擄/ 30 擄scheme and the original scheme at 3600r / min is analyzed to ensure the accuracy of the analysis. The simulation model of the whole working process of the engine including the air exchange process and the combustion process is established. Through the comparison and analysis of the combustion process with the original scheme, it is found that the final optimization scheme is selected. The flow pattern in the cylinder is more reasonable, which speeds up the evaporation and atomization of the fuel to a certain extent, and the distribution of the combustible mixture is more uniform at the same time. Finally, the P-V curve of the whole working process is calculated and it is found that the improved scheme has higher engine power and lower fuel consumption.
【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TK421

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