二沖程點燃式直噴重油發(fā)動機混合氣形成CFD仿真研究
發(fā)布時間：2018-09-08 12:27
【摘要】：重油燃料蒸發(fā)性差,二沖程發(fā)動機壓縮終了時缸內氣體滾流速度較高,噴油時刻對缸內混合氣濃度分布影響很大,從而影響發(fā)動機燃燒的穩(wěn)定性。為保證標定試驗時發(fā)動機的安全,本文通過CFD仿真研究二沖程點燃式重油發(fā)動機缸內混合氣形成過程,得出以下結論:發(fā)動機轉速為40000rpm,油門開度為18°時,噴油結束角為40°CA BTDC時,火花塞電極周圍混合氣濃度較稀,解釋了過去在發(fā)動機標定試驗過程中,該工況以及該噴油結束角的情況下,發(fā)動機出現失火現象的原因。油門開度為18°,轉速為4000rpm和4500rpm時,其使燃燒穩(wěn)定的適宜的噴油結束角的范圍分別在80°~120°CA BTDC附近和100°~140°CA BTDC附近。轉速為4000rpm,油門開度分別為18°,32°和44°,使燃燒穩(wěn)定的適宜的噴油結束角的范圍分別在80°~120°CA BTDC附近,100°~160°CA BTDC附近和120°~160°CA BTDC附近,說明隨著發(fā)動機負荷加大,使燃燒穩(wěn)定的適宜的噴油結束角的范圍有提前的趨勢。發(fā)動機轉速為4000rpm,在小負荷的工況下(18°),掃氣側火花塞主要起點火作用,而在中等負荷(32°)和大負荷(44°)的工況下,排氣側火花塞起主要點火作用,其驗證了使用雙火花塞的必要性。本文最后在二沖程點燃式重油發(fā)動機上進行試驗,結果表明:油門開度為18°,轉速分別為4000rpm和4500rpm時,其最大扭矩所對應的噴油結束角分別為100°CA BTDC和130°CA BTDC;發(fā)動機轉速為4000rpm,油門開度為32°和44°時,其最大扭矩所對應的噴油結束角分別為140°CA BTDC和150°CA BTDC。其最大扭矩對應的噴油結束角處于仿真結果的范圍內。驗證了缸內混合氣形成的CFD仿真結果的一致性,從而為發(fā)動機臺架標定試驗噴油策略提供了一定的指導意義。
[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.
【學位授予單位】：南京航空航天大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TK401
本文編號：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.
【學位授予單位】：南京航空航天大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TK401
【引證文獻】
相關期刊論文 前1條
1 牛燕華;魏民祥;吳偉建;季昊成;;二沖程缸內直噴發(fā)動機燃燒室設計[J];重慶理工大學學報(自然科學);2017年04期
，本文編號：2230517
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