Orkun Özener

High-powered, heavy-duty diesel engines are widely used in transportation, construction, railways, and marine applications. Optimizing valvetrain dynamics is crucial for improving fuel efficiency and reducing emissions. This study presents an integrated multibody dynamics (MBD) and experimental validation approach for a novel heavy-duty diesel engine valvetrain design. The development of the kinematic and dynamic models was motivated by the necessity to analyze valvetrain behavior, identify operational challenges, and optimize key parameters such as the position of the elephant foot and valve lift. The optimized design was validated through experimental testing using vibration measurements at multiple engine points. The results demonstrate that the proposed modifications effectively mitigate valve bounce, improve stability, and enhance engine performance. The validated model provides a foundation for further advancements in valvetrain optimization, contributing to improved efficiency in heavy-duty diesel engines.

At the very beginning of the design phase of a forklift truck, it must be determined which drive systems will be used. Then, with these drive systems and the target weight, it must be calculated how many litres of fuel the truck burns according to VDI 2198. In this study, a forklift truck will be modelled in Mat-Lab environment with all its sub-systems and run in a cycle in accordance with VDI 2198. One of the biggest outputs of this study will be to know the fuel consumption of this forklift during the forklift design phase.

Forkliftlerin kullanım alanları ve amaçları düşünüldüğünde ve aynı zamanda operatörlerin de istekleri göz önüne alındığında bir forkliftten beklenen isteklerin en başında performans beklentisi gelmektedir, operatörler forkliftlerinden doğrudan “hızlı” ve “atik” bir performansa sahip olmalarını beklemektedirler. Bu beklentiler doğrultusunda forkliftler incelendiğinde performansı doğrudan etkileyecek alt sistemin motor ve tahrik sistemi olduğu gözükmektedir. Forkliftlerin alt sistemleri genelde forkliftlere özel hesaplanan, tasarlanan ve üretimi yapılan sistemler değillerdir, forklift üreticileri bu alt sistemleri raf ürünleri arasından seçmekte ve kullanmaktadırlar. Bu minvalde düşünüldüğünde optimum bir raf ürünü alt sistemin seçilmesi kritik önem arz etmektedir. Bu çalışmada da motor hariç iki farklı markaya, tasarıma, orana ve verime sahip transmisyon, tork dönüştürücü, diferansiyel ve hız azaltıcı alt sistemlerinin performans açısından mukayeseleri irdelenecektir.

This work presents a numerical study that investigates the optimum post-injection strategy and internal exhaust gas recirculation (iEGR) application with intake valve re-opening (2IVO) aiming to optimize the brake specific nitric oxide (bsNO) and brake specific soot (bsSoot) trade-off with reasonable brake specific fuel consumption (BSFC) via 1D engine cycle simulation. For model validation, single and post-injection test results obtained from a heavy-duty single cylinder diesel research engine were used. Then, the model was modified for 2IVO application. Following the simulations performed based on Latin hypercube DoE; BSFC, bsNO and bsSoot response surfaces trained by feedforward neural network were generated as a function of the injection (start of main injection, post-injection quantity, post-injection dwell time) and iEGR (2IVO dwell) parameters. After examining the effect of each parameter on pollutant emission and engine performance, multi-objective pareto optimization was performed to obtain pareto optimum solutions in the BSFC-bsNO-bsSoot space for 8.47 bar brake mean effective pressure (BMEP) load and 1500 rpm speed condition. The results show that iEGR and post-injection can significantly reduce NO and soot emissions, respectively. The soot oxidation capability of post-injection comes out only if it is not too close to the main injection and its efficiency and effective timing are substantially affected by iEGR rate and main injection timing. It could also be inferred that by the combination of iEGR and post-injection, NO and soot could be reduced simultaneously with a reasonable increase in BSFC if start of main injection is phased properly.