Jafari, Rahim

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Otomobil Fren Diskinin Termal Performansının Ölçülmesi
(2023) Erkılıç, Kaan Tamer; Jafarı, Rahım
Hızlanma bir araç için çok önemli bir dinamiktir, ancak yavaşlama araç güvenliği için kilit unsurdur. Fren sistemi otomobili yavaşlatacak veya durduracak en önemli ekipmandır. Bir fren sisteminin işlevi, disk ve balatanın sürtünmesi ile gerçekleşir. İçerdiği komponentlerin tasarım ve test adımlarında ısıl performansları hassas bir şekilde ölçülmeli ve komponentin çalışma koşulları altında gereken performansı göstermesi gerekmektedir. Bu çalışmada, fren disklerinin hem aerodinamik hem de termal karakteristiklerinin gözlemleneceği bir deney düzeneği tasarlanmış ve üretilmiştir. Deney düzeneği üzerindeki disk, balata, jant ve lastik gibi parçalar tipik bir binek otomobilde kullanılanlar ile birebir aynıdır. Komponentlerle birlikte binek bir otomobilin çeyrek ağırlığı deney düzeneğine silindirik ağırlıklar yardımıyla şaft üzerine uyarlanmıştır. Bunun yanında, deney düzeneğinde tekrarlamalı fren senaryosu kullanılmış olup frenlemenin aerodinamik ve termal çıktılarının ayrıntılı numerik modeller kullanılarak simülasyonları gerçekleştirilmiştir. Gerçekleştirilen deneyler ve simülasyonlarda, otomobilin hızı sebebiyle oluşan hava akışının jant içerisinde yavaşladığı ve buna rağmen jant içerisinde türbülanslı bir hava akışı olduğu gözlemlendi. Termal simülasyonlar ve deneyler sonucunda ise fren diski üzerindeki sıcaklık dağılımı gözlemlenmiş olup fren diskinin balata ile temas ettiği alanın temas alanının tam karşısındaki alanın sıcaklığına göre daha yüksek olduğu ve sıcaklığın eşit dağılmadığı tahmin edilmiştir.
Tek Silindirli Hbo Motorun Performans Gelişimi
(2020) Fendal, Metin; Jafarı, Rahım
The development of 2 and 4 stroke cycle prototype spark ignition engines using gasoline, manufactured by Minisan A.Ş., is intended in this study. The engines, designed to operate with carburetors and conventional ignition system, functioned successfully. The first designed engine was manufactured with a similar cylinder head, valve configuration, spark plug location and equal cylinder diameter and piston stroke with the ACME model engine, for comparison. The geometry of the connecting rod was altered. The center of the crankshaft shifted approximately 40 – 70 mm from the center of the cylinder. The specific fuel consumption of the new engine was lower and a decision was made to develop it. After the first 340 cc prototype, 2 cylinder, air and water cooled prototype engines were manufactured. A 340 cc engine was also developed within the scope of this thesis. Appropriate combustion chamber geometry and valve configuration for the thermodynamic cycle of these engines were not included in this study. Within the scope of the thesis, commercial electronic fuel injection and ignition systems were acquired and adapted to the engines. These systems were operated by electronic control units (ECU) which were acquired. Theoretical simulation and experimental performance and mapping work were done on the engines for programming the ECU. Two dimensional tables were constructed for the injectors and igniton systems to follow according to the working modes of the engines and were uploaded to the ECU's. Performance tests were conducted with the iv upgraded electronic injection and ignition system of the engines. In comparison to the operation of the engines with carburetors and conventional ignition system, for same engine speed ranges and loads up to 20 percent increase was observed for the excess air coefficient and up to 30 percent decrease was observed for the brake specific fuel consumption. Keywords: Internal combustion engine, ignition system, performance evaluation tests.

Journal	Count
Case Studies in Thermal Engineering	1
Energy and Buildings	1
Experimental Thermal and Fluid Science	1
IICETA 2022 - 5th International Conference on Engineering Technology and its Applications -- 5th International Conference on Engineering Technology and its Applications, IICETA 2022 -- 31 May 2022 through 1 June 2022 -- Al-Najaf -- 183264	1
International Advanced Researches and Engineering Journal	1

Jafari, Rahim

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