Contents lists available at Mapta Publishing Group Mapta Journal of Mechanical and Industrial Engineering (MJMIE) journal homepage: http://maptapublishing.com/index.php/mjmie Vol. 3, No. 2, August, 2019 ISSN: 2517-4258 9 Numerical Investigation on the Effect of Piston Bowl Geometry on Combustion Characteristics of a Heavy-Duty Diesel Engine Oladapo M. Adeniyi * Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne, United Kingdom Article Info Abstract Article history: Received May 20 th , 2019 Revised Jul 18 th , 2019 Accepted August 14 th , 2019 Today, due to increased efficiency of heavy-duty diesel engines in the global industry, discussion of the performance of these motors, including higher efficiency and lower emissions, is very important. Several methods exist to meet these demands by the diesel engine. Piston bowl geometry deformation strategy is a reliable method for achieving pollutants of lower nitrogen oxides (Nox) and soot and higher yield. This paper has used Converge software to model the CFD for the performance of a Caterpillar 3401 engine with three different piston bowl geometries and various depths and chamfers for one of the geometries. The compression, inlet temperature, and pressure ratio are assumed to be constant. The results of efficiency and pollution of the engine are presented at all stages for analysis, comparisons, and conclusions. The results show that the cylindrical piston bowl geometry has a proper performance in terms of efficiency and the pollutions produced. Keyword: Heavy-duty diesel engine CFD numerical modelling Efficiency and emissions 1. Introduction Due to higher compression ratio, diesel or compression ignition (CI) engines have higher efficiency than gasoline engines. Due to rising fuel prices and increasing attention to the problem of air pollution, they have recently been the focus of attention [1-3]. But due to the direct injection of fuel into the cylinder of the diesel engines near the high point of death, part of the cylinder has a rich mixture and the other parts have a poor mixture which results in the formation of soot and nitrogen oxides pollutants, respectively; they have been an obstacle to the development of the engine. One of the potentials for reducing HC and CO pollutants, thus increasing the efficiency of combustion, is the optimization of the piston bowl geometry design [4, 5]. Several studies are provided in the field of effects of geometric factors and fuel injection on the performance of the diesel engine by different methods [6-10]. Wang et al [9] investigated the effects of diesel engine piston bowl geometry, which works with biodiesel fuels, on combustion and pollutions. He studied three different piston bowl geometries and used Kiva code integrated by Chemkin to simulate the combustion process. According to the results, the optimal piston was dependent on speed. Results have shown that at low speeds, SCC has higher indicatory work, cylinder pressure, combustion temperature, and consequently, releases more nitrogen oxides; and OCC has better performance at medium and high speed. Kokjohn et al [8] studied RCCI performance at different loads and two modes of single-injector and dual-injection fuel injections using Converge software code and experimental method. The results indicated that the dual-injection strategy has been suitable for low and medium loads, and single-injector strategy has been proposed for higher loads. Park [10] optimized the combustion chamber geometry and the operating conditions for compression ignition engines which work with dimethyl ether fuel. Also, Donateo et al [11] and Genzale et al [12] predicted the combustion process using a genetic algorithm and achieved the combustion chamber and piston bowl curve suitable for methane-fueled engines. Using numerical methods, Rakopoulos et al [13] studied the piston geometry of a diesel engine and investigated three different piston geometries in three different speeds. Also, Jovanovic et al [14] compared two omega-shaped and cylindrical piston bowls and the spatial distribution of the kinetic energy and the flow pattern in the two-piston bowls in * Corresponding author: oladapo.adeniyi67@gmail.  This is an open access article under the CC-BY license (https://creativecommons.org/licenses/by/4.0/). © Authors retain all copyrights.