Pamukkale Univ Muh Bilim Derg. Ahead of Print: PAJES-23565 | DOI: 10.5505/pajes.2023.23565

An experimental study on cycle-to-cycle combustion variations at different speeds in a common-rail diesel engine

Ali Þanlý¹, ilker turgut yýlmaz^2
1Piri Reis Vocational And Technical Anatolian High School
²Marmara University, Technology Faculty, Mechanical Engineering

The objective of this study is to experimentally investigate cyclic combustion variabilities in a four-cylinder automotive common-rail diesel engine at different engine speeds, including 1600, 1800, and 2000 rpm. The investigation evaluates the relative effects of speeds on the cyclic discrepancies in a modern diesel engine. 1000 cyclic combustion data including peak combustion pressure (Pmax), peak pressure rise rate (PRRmax) and indicated mean effective pressure (IMEP) were analyzed in the experimental study. It was found that the cyclic fluctuations in combustion pressure in each engine speed were minor, but detailed comparison of Pmax, PRRmax, and IMEP revealed noteworthy differences in the studied cycles. Higher cylinder temperatures and air movement improved combustion. Therefore, not only coefficient of variations COVs of IMEP and Pmax decreased, but also mean Pmax and PRRmax increased with increasing engine speed. On the other hand, the friction effect of the intake air reduced the positive effects of improved combustion with increasing engine speed and as a result mean IMEP decreased. COVs of IMEP and Pmax remained below 1% at all speeds, thus stable and regular combustion was maintained even in a numerous range of the cycle numbers. Pre-injection phase of fuel injection system was recognized to be effective in formation of the first peak of the combustion pressure in individual cycles. It was concluded from this study that the common-rail diesel engine generated minor cyclic discrepancies under different engine speeds.

Keywords: Cyclic variations, combustion parameters, common-rail diesel engine

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Ortak hatlý bir dizel motorda farklý devirlerde çevrimden çevrime yanma deðiþimleri üzerine deneysel bir çalýþma

Ali Þanlý¹, ilker turgut yýlmaz^2
1Piri Reis Mesleki Ve Teknik Anadolu Lisesi
²Marmara Üniversitesi, Teknoloji Fakültesi, Makine Mühendisliði

Bu çalýþmanýn amacý, dört silindirli ortak hatlý bir otomotiv dizel motorunda 1600, 1800, 2000 d/dak’lýk devirlerde çevrimsel yanma deðiþimlerini deneysel olarak incelemektedir. Çalýþma, bir modern dizel motorda devir sayýsýnýn çevrimsel farklýlýklara baðlý etkisini ele almaktadýr. Maksimum yanma basýncý (SBmaks), maksimum basýnç artýþ oraný (BAOmaks), ve ortalama indike basýnç (OÝB) parametrelerini kapsayan 1000 çevrimsel yanma verisi deneysel çalýþmada analiz edilmiþtir. Her bir motor hýzýnda, silindir basýncýndaki çevrimsel deðiþimlerin minimum olduðu, ancak SBmaks, BAOmaks ve OÝB detaylý olarak karþýlaþtýrýldýklarýnda incelenen çevrimlerde önemli farklýlýklar ortaya çýkmýþtýr. Daha yüksek silindir sýcaklýklarý ve hava hareketleri yanmayý iyileþtirmiþtir. Böylece, artan motor devriyle birlikte sadece OÝB ve SBmaks’ýn çevrimsel deðiþim katsayýlarý (ÇDK) azalýrken, ayný zamanda ortalama SBmaks ve BAOmaks artmýþtýr. Diðer taraftan, artan devirle birlikte emme havasýnýn sürtünme etkisi, iyileþen yanmanýn pozitif etkilerini azaltmýþ ve sonuç olarak ortalama OÝB azalmýþtýr. SBmaks ve OÝB’nin ÇDK’larý tüm devirlerde %1’in altýnda kalmýþtýr, böylece oldukça geniþ çevrim sayýlarýnda bile stabil ve düzenli yanma sürdürülmüþtür. Her bir çevrimde, yakýt sistemi ön enjeksiyon fazýnýn, ilk yanma basýnç pikinin oluþumunda etkili olduðu gözlenmiþtir. Bu çalýþmadan, ortak hatlý dizel motorun farklý devirlerde küçük çevrimsel farklýlýklar meydana getirdiði sonucuna varýlmýþtýr.

Anahtar Kelimeler: Çevrimsel deðiþimler, yanma parametreleri, ortak hatlý dizel motor

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