İki zamanlı ters-doğru akışlı buji ile ateşlemeli bir motorun tasarımı, imali ve performans testleri
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Tarih
2017
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Karabük Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Yeni nesil iki zamanlı motorları geliştirmek için taze dolgu kaybı, düşük yükte düzensiz yanma ve egzoz emisyonlarının azaltılması gibi ele alınması gereken birçok problem vardır. En acil problemler, süpürme boyunca kısa devrenin sebep olduğu yakıt tüketimi artışı ve oldukça yoğun HC emisyonudur. İki zamanlı motorların bu kusurlarını ortadan kaldırmak amacıyla geliştirilen süpürme yöntemlerinden biri de ters-doğru akışlı tip süpürme yöntemidir. Bu çalışmada, piyasada kullanılması mümkün olabilecek 97 cm3'lük iki zamanlı ters-doğru akışlı karbüratörlü buji ile ateşlemeli bir motor tasarlanmış ve imal edilmiştir. Motorun çevrim analizi teorik matematiksel model kullanılarak belirlenmiş ve yapılan deneylerle motorun yanma analizi, performansı ve egzoz emisyonları incelenmiştir. Teorik çevrim analizi için iki zamanlı ters doğru akışlı buji ile ateşlemeli bir motorun gerçek çevrim hesaplamalarını içeren termodinamiksel bir model geliştirilmiştir ve bu modele göre MATLAB programlama dilinde bir bilgisayar programı yazılarak motorun performansını ortaya koyan diyagramlar elde edilmiştir. Deneylerde öncelikle, motora uygulanan gerçek zamanlı bir yanma analizi sistemi ile yanma değerlerinin çevrimiçi analizi ve sayısal verilerin toplanması mümkün kılınmıştır. Yanma analizi deneyleri motorun ideal yanma fazını belirlemek amacıyla tam yükte, 1800 1/dk'da ve ateşleme avansının ÜÖN'dan önce 16-24 ºKA arasında 4 ºKA aralıklarla değiştirilmesi ile gerçekleştirilmiş ve silindir basıncı, kütlesel yanma oranı profili, ısı salınımı hızı ve indike verim değişimleri incelenmiştir. Daha sonra deneyler motor performans parametrelerinin belirlenmesi amacıyla, ideal ateşleme avansında, tam ve kısmi yüklerde, motor devrinin 1000 1/dk ile 2000 1/dk arasında 200 1/dk aralıklarla değiştirilmesi ile sürdürülmüştür. Son olarak motor 1800 1/dk'lık sabit hızda, tam ve kısmi yüklerde çalıştırılarak egzoz emisyon değerleri belirlenmiştir. Yapılan deneyler, test motoru için ideal yanma fazının ateşleme avansının ÜÖN'dan önce 20 ºKA'na ayarlanması ile elde edildiğini göstermiştir. 20 ºKA'lık optimum ateşleme avansı değeri için maksimum fren momenti 4,40 Nm olarak belirlenmiştir. Motor performans parametreleri, teorik analiz sonuçları ve deneysel verilerle kıyaslamalı olarak verilmiş ve deneysel sonuçlar klasik iki zamanlı bir motorun ve dört zamanlı bir motorun performans değerleriyle kıyaslanmıştır. Deney motorunun performans değerleri klasik iki zamanlı bir motordan üstün olup, dört zamanlı bir motorla rekabet edebilecek seviyededir. Deneylerden elde edilen veriler teorik analiz sonuçları ile uyuşmaktadır.
In order to develop new generation two-stroke engines, there are many problems to be handled like the loss of fresh charge, unsteady combustion at low engine loads, and decreasing the exhaust emission. The most urgent problems are the increase in the consumption of the fuel during the scavenging caused by short circuit and the extremely intense HC emission. One of the scavenging methods developed in order to eliminate the above mentioned defects of two-stroke engines is the Reverse-Uniflow Type Scavenging Method. In this study, a 97 cc, two-stroke engine with reverse-uniflow carburetor and spark ignition was designed and produced. It is possible that the engine may also be used in the market. The cycle analysis of the engine was determined by using a theoretical mathematical model, and the combustion analysis, performance and exhaust emission of the engine was examined with experiments. A thermodynamic model that includes real cycle calculations of a two-stroke reverse-uniflow spark ignition engine has been developed for theoretical cycle analysis, and the diagrams that reveal the performance of the engine has been obtained by writing a computer program that was developed in MATLAB programming language. In the experiments, firstly, the online analysis of the combustion values and the collection of the numerical data were made possible with a Real-Time Combustion Analysis System applied to the engine. In order to determine the ideal combustion phase of the engine, the combustion analysis experiments were performed at full load, at 1800 1/min, and by changing the ignition period between 16-24 ºCA with 4-unit intervals before TDC; and the cylinder pressure, mass fraction burned profile, heat release rate and indicated efficiency changes were observed. Then, the experiments were continued in order to determine the engine performance parameters at ideal ignition period, under full and low loads, between 1000 1/min and 2000 1/min engine rpm by changing it with 200 1/min interval. As the last item, the engine was started at 1800 1/min fixed speed with full and partial loads, and the exhaust emission values were determined. The experiments showed that the most ideal ignition phase for the Test Engine was obtained when the ignition period was adjusted to 20 ºCA before TDC. The maximum brake moment for 20º CA the optimum ignition advance value was determined as 4,40 Nm. The engine performance parameters have been shown in a comparative manner with theoretical analysis results and empirical data, and the empirical results have been compared with the performances of a classical two-stroke engine and a four-stroke engine. The performance values of the test engine are superior to a classic two-stroke engine; and the Test Engine is capable of competing with a four-stroke engine. The data obtained in the study comply with the theoretical analysis results.
In order to develop new generation two-stroke engines, there are many problems to be handled like the loss of fresh charge, unsteady combustion at low engine loads, and decreasing the exhaust emission. The most urgent problems are the increase in the consumption of the fuel during the scavenging caused by short circuit and the extremely intense HC emission. One of the scavenging methods developed in order to eliminate the above mentioned defects of two-stroke engines is the Reverse-Uniflow Type Scavenging Method. In this study, a 97 cc, two-stroke engine with reverse-uniflow carburetor and spark ignition was designed and produced. It is possible that the engine may also be used in the market. The cycle analysis of the engine was determined by using a theoretical mathematical model, and the combustion analysis, performance and exhaust emission of the engine was examined with experiments. A thermodynamic model that includes real cycle calculations of a two-stroke reverse-uniflow spark ignition engine has been developed for theoretical cycle analysis, and the diagrams that reveal the performance of the engine has been obtained by writing a computer program that was developed in MATLAB programming language. In the experiments, firstly, the online analysis of the combustion values and the collection of the numerical data were made possible with a Real-Time Combustion Analysis System applied to the engine. In order to determine the ideal combustion phase of the engine, the combustion analysis experiments were performed at full load, at 1800 1/min, and by changing the ignition period between 16-24 ºCA with 4-unit intervals before TDC; and the cylinder pressure, mass fraction burned profile, heat release rate and indicated efficiency changes were observed. Then, the experiments were continued in order to determine the engine performance parameters at ideal ignition period, under full and low loads, between 1000 1/min and 2000 1/min engine rpm by changing it with 200 1/min interval. As the last item, the engine was started at 1800 1/min fixed speed with full and partial loads, and the exhaust emission values were determined. The experiments showed that the most ideal ignition phase for the Test Engine was obtained when the ignition period was adjusted to 20 ºCA before TDC. The maximum brake moment for 20º CA the optimum ignition advance value was determined as 4,40 Nm. The engine performance parameters have been shown in a comparative manner with theoretical analysis results and empirical data, and the empirical results have been compared with the performances of a classical two-stroke engine and a four-stroke engine. The performance values of the test engine are superior to a classic two-stroke engine; and the Test Engine is capable of competing with a four-stroke engine. The data obtained in the study comply with the theoretical analysis results.
Açıklama
Fen Bilimleri Enstitüsü, Makine Eğitimi Ana Bilim Dalı
Anahtar Kelimeler
Makine Mühendisliği, Mechanical Engineering
