Shahrood University of Technology Journal of Solid and Fluid Mechanics 2251-9475 15 2 2025 05 22 Numerical investigation of different combustion chamber geometries and injection angles in a direct injection diesel engine Numerical investigation of different combustion chamber geometries and injection angles in a direct injection diesel engine 95 110 3555 10.22044/jsfm.2025.15947.3951 FA Javad Khadem Assoc. Prof., Department of Mechanical Engineering, Faculty of Engineering, University of Birjand, Birjand, Iran. Mohammad Shahkolayi MSc, Department of Mechanical Engineering, Faculty of Engineering, University of Birjand, Birjand, Iran . Ali Asadi Assist. Prof., Department of Mechanical Engineering, Faculty of Engineering, Bozorgmehr University of Qaenat, Qaen, Iran. Afshin Fahimi Rad MSc., Mechanical Engineering, Research and Development Department, Iran Heavy Diesel Plant. Journal Article 2025 03 18 Proper design of the combustion chamber geometry and selection of the optimal fuel injection angle are key factors in reducing fuel consumption and pollutant emissions in direct injection diesel engines. In this paper, a numerical study of different combustion chamber geometries and injection angles for the 16RK215heavy-duty diesel engine has been conducted. Four different combustion chamber designs and four fuel injection angles, ranging from 130 to 160 degrees were examined. Using numerical simulations with the AVL-Fire computational code, the most suitable combustion chamber design and compatible fuel injection system were selected. An injection angle of 150 degrees and geometry number one showed the best overall performance. The highest NOx emissions were observed in geometry number one, the highest unburned hydrocarbons and soot emissions in geometry number four. The heat release rate, as a crucial parameter of combustion efficiency, reached its peak value in geometry number one. In all geometries, the highest peak temperature and average pressure were obtained at a 150-degree injection angle. Proper design of the combustion chamber geometry and selection of the optimal fuel injection angle are key factors in reducing fuel consumption and pollutant emissions in direct injection diesel engines. In this paper, a numerical study of different combustion chamber geometries and injection angles for the 16RK215heavy-duty diesel engine has been conducted. Four different combustion chamber designs and four fuel injection angles, ranging from 130 to 160 degrees were examined. Using numerical simulations with the AVL-Fire computational code, the most suitable combustion chamber design and compatible fuel injection system were selected. An injection angle of 150 degrees and geometry number one showed the best overall performance. The highest NOx emissions were observed in geometry number one, the highest unburned hydrocarbons and soot emissions in geometry number four. The heat release rate, as a crucial parameter of combustion efficiency, reached its peak value in geometry number one. In all geometries, the highest peak temperature and average pressure were obtained at a 150-degree injection angle. https://jsfm.shahroodut.ac.ir/article_3555_f99294d6ac321341efc045c0dca6fab6.pdf