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This investigation deals with the EF7 (TC) engine, a dual fuel engine equipped with a turbocharger system, consequently with a high probability of knock inception. In this study, an operating cycle of the engine was simulated using KIVA-3V code. Some modifications were carried out on the KIVA method of calculating pressure in the intake port in order to simulate turbocharger pressure correctly. Auto-ignition and knock were then simulated using the auto-ignition integral model. The modified code and the simulation were verified using three different methods; in-cylinder average pressure, gas temperature of the exhaust port, and auto-ignition timing. The simulation results using the auto-ignition integral model, as compared with the experimental data, proved to be reasonably accurate. Following this validation, the effect of the knock phenomenon on the engine heat transfer through the walls was investigated. The simulations showed that the rate of heat transfer through the walls under knocking conditions is about 2.2 times higher than that under normal conditions. However, it was also shown that the total heat transfer increases about 15%.

The global warming crisis and strict regulations have pushed the automotive industry into technological change, but it will take time, so finding quick solutions can be very helpful. Using water in diesel emulsion is one of the low-cost and fast solutions to reduce pollution and improve the performance of diesel engines. In this study, the effects of adding water to diesel fuel and the phenomena that occur when water enters the combustion chamber are investigated. For this purpose, a simulation of a four-cylinder diesel engine has been used with different content of water in diesel (0% or pure diesel, 5%, 10%, 15%, and 20%). The simulations are performed in Converge CFD using dynamic mesh and adaptive mesh refinement. The results showed that the use of water in diesel leads to an improvement of about 10% in engine indicated power and a simultaneous reduction in soot and NOx by 10 and 30%, respectively. The simulation results showed that water droplet micro-explosions accelerated the fuel droplet breakup process and reduced the combustion duration by 10%–30%.

Spray simulation is the basis of many engine simulations and directly impacts the quality of other simulations. Various models have been proposed to simulate spraying and the breakup and evaporation of fuel particles. The Kelvin–Helmholtz/Rayleigh–Taylor (KH-RT) model is one of the most common of these models. In this study, while analyzing the sensitivity of the KH-RT model constants on spray simulation, the effect of the LES and RANS turbulence model on spray penetration length and shape of the diesel spray contour is investigated. This study shows that both LES and RANS turbulence models along with the KH-RT model predict the spray penetration length with appropriate accuracy. While the RANS model, due to its averaging nature, does not accurately simulate the shape of the spray contour, which has very soft edges. Finally, the best method for simulating diesel spray and the proposed constants of the KH-RT model is presented.

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