二沖程點(diǎn)燃式直噴重油發(fā)動(dòng)機(jī)混合氣形成CFD仿真研究
發(fā)布時(shí)間：2018-09-08 12:27
【摘要】：重油燃料蒸發(fā)性差,二沖程發(fā)動(dòng)機(jī)壓縮終了時(shí)缸內(nèi)氣體滾流速度較高,噴油時(shí)刻對(duì)缸內(nèi)混合氣濃度分布影響很大,從而影響發(fā)動(dòng)機(jī)燃燒的穩(wěn)定性。為保證標(biāo)定試驗(yàn)時(shí)發(fā)動(dòng)機(jī)的安全,本文通過(guò)CFD仿真研究二沖程點(diǎn)燃式重油發(fā)動(dòng)機(jī)缸內(nèi)混合氣形成過(guò)程,得出以下結(jié)論:發(fā)動(dòng)機(jī)轉(zhuǎn)速為40000rpm,油門(mén)開(kāi)度為18°時(shí),噴油結(jié)束角為40°CA BTDC時(shí),火花塞電極周圍混合氣濃度較稀,解釋了過(guò)去在發(fā)動(dòng)機(jī)標(biāo)定試驗(yàn)過(guò)程中,該工況以及該噴油結(jié)束角的情況下,發(fā)動(dòng)機(jī)出現(xiàn)失火現(xiàn)象的原因。油門(mén)開(kāi)度為18°,轉(zhuǎn)速為4000rpm和4500rpm時(shí),其使燃燒穩(wěn)定的適宜的噴油結(jié)束角的范圍分別在80°~120°CA BTDC附近和100°~140°CA BTDC附近。轉(zhuǎn)速為4000rpm,油門(mén)開(kāi)度分別為18°,32°和44°,使燃燒穩(wěn)定的適宜的噴油結(jié)束角的范圍分別在80°~120°CA BTDC附近,100°~160°CA BTDC附近和120°~160°CA BTDC附近,說(shuō)明隨著發(fā)動(dòng)機(jī)負(fù)荷加大,使燃燒穩(wěn)定的適宜的噴油結(jié)束角的范圍有提前的趨勢(shì)。發(fā)動(dòng)機(jī)轉(zhuǎn)速為4000rpm,在小負(fù)荷的工況下(18°),掃氣側(cè)火花塞主要起點(diǎn)火作用,而在中等負(fù)荷(32°)和大負(fù)荷(44°)的工況下,排氣側(cè)火花塞起主要點(diǎn)火作用,其驗(yàn)證了使用雙火花塞的必要性。本文最后在二沖程點(diǎn)燃式重油發(fā)動(dòng)機(jī)上進(jìn)行試驗(yàn),結(jié)果表明:油門(mén)開(kāi)度為18°,轉(zhuǎn)速分別為4000rpm和4500rpm時(shí),其最大扭矩所對(duì)應(yīng)的噴油結(jié)束角分別為100°CA BTDC和130°CA BTDC;發(fā)動(dòng)機(jī)轉(zhuǎn)速為4000rpm,油門(mén)開(kāi)度為32°和44°時(shí),其最大扭矩所對(duì)應(yīng)的噴油結(jié)束角分別為140°CA BTDC和150°CA BTDC。其最大扭矩對(duì)應(yīng)的噴油結(jié)束角處于仿真結(jié)果的范圍內(nèi)。驗(yàn)證了缸內(nèi)混合氣形成的CFD仿真結(jié)果的一致性,從而為發(fā)動(dòng)機(jī)臺(tái)架標(biāo)定試驗(yàn)噴油策略提供了一定的指導(dǎo)意義。
[Abstract]:The vaporization of heavy oil fuel is poor, the gas rolling velocity in cylinder is higher at the end of compression of two-stroke engine, and the fuel injection time has a great influence on the mixture concentration distribution in the cylinder, thus affecting the combustion stability of the engine. In order to ensure the safety of the engine during the calibration test, the formation process of the mixture in the cylinder of the two-stroke ignition heavy oil engine is studied by CFD simulation. The following conclusions are obtained: when the engine speed is 40000rpm, the throttle opening is 18 擄, the fuel injection end angle is 40 擄CA BTDC. The concentration of mixture around the spark plug electrode is relatively thin, which explains the cause of engine misfire under the condition of this condition and the end angle of the fuel injection during the past engine calibration test. When the throttle opening is 18 擄and the rotational speed is 4000rpm and 4500rpm, the suitable range of fuel injection end angle for combustion stability is about 80 擄CA BTDC and 140 擄CA BTDC, respectively. The rotational speed is 4000rpm and the throttle opening is 18 擄/ 32 擄and 44 擄, respectively. The suitable end angle of fuel injection for stable combustion is in the range of 80 擄~ 120 擄CA BTDC and 120 擄~ 160 擄CA BTDC and 160 擄CA BTDC respectively, which indicates that the engine load increases with the increase of engine load. The range of suitable end angles for fuel injection to stabilize combustion tends to advance. The engine speed is 4000rpm, under the condition of small load (18 擄), the scavenging side spark plug mainly ignites, but under the condition of medium load (32 擄) and high load (44 擄), the exhaust side spark plug plays the main role of ignition, which verifies the necessity of using double spark plug. In the end, the test is carried out on a two-stroke ignition heavy oil engine. The results show that when the throttle opening is 18 擄and the rotational speed is 4000rpm and 4500rpm, respectively, The fuel injection end angle corresponding to the maximum torque is 100 擄CA BTDC and 130 擄CA BTDC; engine speed is 4000rpm, and when the throttle opening is 32 擄and 44 擄, the fuel injection end angle corresponding to the maximum torque is 140 擄CA BTDC and 150 擄CA BTDC., respectively. The fuel injection end angle corresponding to its maximum torque is within the range of simulation results. The consistency of CFD simulation results of in-cylinder mixture formation is verified, which provides some guidance for the injection strategy of engine bench calibration test.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TK401
本文編號(hào)：2230517
[Abstract]:The vaporization of heavy oil fuel is poor, the gas rolling velocity in cylinder is higher at the end of compression of two-stroke engine, and the fuel injection time has a great influence on the mixture concentration distribution in the cylinder, thus affecting the combustion stability of the engine. In order to ensure the safety of the engine during the calibration test, the formation process of the mixture in the cylinder of the two-stroke ignition heavy oil engine is studied by CFD simulation. The following conclusions are obtained: when the engine speed is 40000rpm, the throttle opening is 18 擄, the fuel injection end angle is 40 擄CA BTDC. The concentration of mixture around the spark plug electrode is relatively thin, which explains the cause of engine misfire under the condition of this condition and the end angle of the fuel injection during the past engine calibration test. When the throttle opening is 18 擄and the rotational speed is 4000rpm and 4500rpm, the suitable range of fuel injection end angle for combustion stability is about 80 擄CA BTDC and 140 擄CA BTDC, respectively. The rotational speed is 4000rpm and the throttle opening is 18 擄/ 32 擄and 44 擄, respectively. The suitable end angle of fuel injection for stable combustion is in the range of 80 擄~ 120 擄CA BTDC and 120 擄~ 160 擄CA BTDC and 160 擄CA BTDC respectively, which indicates that the engine load increases with the increase of engine load. The range of suitable end angles for fuel injection to stabilize combustion tends to advance. The engine speed is 4000rpm, under the condition of small load (18 擄), the scavenging side spark plug mainly ignites, but under the condition of medium load (32 擄) and high load (44 擄), the exhaust side spark plug plays the main role of ignition, which verifies the necessity of using double spark plug. In the end, the test is carried out on a two-stroke ignition heavy oil engine. The results show that when the throttle opening is 18 擄and the rotational speed is 4000rpm and 4500rpm, respectively, The fuel injection end angle corresponding to the maximum torque is 100 擄CA BTDC and 130 擄CA BTDC; engine speed is 4000rpm, and when the throttle opening is 32 擄and 44 擄, the fuel injection end angle corresponding to the maximum torque is 140 擄CA BTDC and 150 擄CA BTDC., respectively. The fuel injection end angle corresponding to its maximum torque is within the range of simulation results. The consistency of CFD simulation results of in-cylinder mixture formation is verified, which provides some guidance for the injection strategy of engine bench calibration test.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TK401
【引證文獻(xiàn)】
相關(guān)期刊論文 前1條
1 牛燕華;魏民祥;吳偉建;季昊成;;二沖程缸內(nèi)直噴發(fā)動(dòng)機(jī)燃燒室設(shè)計(jì)[J];重慶理工大學(xué)學(xué)報(bào)(自然科學(xué));2017年04期
，本文編號(hào)：2230517
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