The increasing complexity of modern engines has rendered the prototyping phase long and expensive. This is where engine modeling becomes in the recent years extremely useful and can be used as an indispensable tool when developing new engine concepts. The thermodynamic performance of a Turbocharged diesel engine with heat transfer and friction term losses is analyzed. This study deals with the numerical simulation and performance prediction of a turbocharged diesel engine with six-cylinder direct injection. To predict the engine performances, we developed a computer program for simulating the operation of a turbocharged diesel engine, and used the commercial GT-Power software to validate the simulation results. The range of variation of the rotational speed of the diesel engine chosen extends from 800 rpm to 2100 rpm. In this paper we studied the influence of several engine parameters on the brake power and effective efficiency. Moreover it puts in evidence the existence of two optimal points in the engine, one relative to maximum power and another to maximum efficiency; it was found that if the injection time is advanced, so the maximum levels of pressure and temperature in the cylinder are high.

Tungsten inert gas (TIG) surface modification with Fe-based alloy can give protection against wear and corrosion of metallic component material. In this study, an attempt has been made to explore deposition of Fe-C-Si preplaced powders on commercial purity titanium (CP-Ti) by TIG torch melting process to improve resistance of substrate to wear. Three different powder blends with nominal composition of 97Fe2C1Si, 94Fe 4C2Si and 91Fe6C3Si were separately melted on CP-Ti using a conventional TIG welding torch produced at 100 A and energy input 1350 J/mm. Analysis of the results showed that TIG torch produced melt pools geometry with good metallurgical bonding with the substrate. The melt microstructure consisted of different TiC precipitates. Pores were conspicuously seen on the melt microstructure after surface modification with highest carbon content (94Fe 4C2Si). Both microhardness and wear property showed a significant improvement particularly after TIG coating with 94Fe4C2Si. Thus, it appears that an optimized composition of Fe-C-Si preplaced powder with 94Fe4C2Si under TIG melting was the best composition to control wear resistance and for the application of cylindrical liner.

In this study, aerodynamic structures of the heavy vehicle consisting of truck and trailer was investigated with computational fluid mechanics method. The force measurement were performed on the model car and aerodynamic drag coefficient (CD) were determined numerically in 4 different speeds on the Fluent® program. Numerical analysis of flow were made on the 59 000 - 844 000 Reynolds number. The effect of trailer additional to truck was determined to aerodynamic drag coefficient. The friction and pressure induced distributions were determined of total aerodynamic resistance. The images of flow structure were obtained around the truck trailer. The zones that was forming aerodynamic resistance were determined.

It is needed to great time and cost to determine drag coefficients of vehicles with full-scale wind tunnels. In this study, drag coefficient of a blunt bus model was tried to be determined using Reynolds number independence. A low speed wind tunnel having a free flow velocity is 28 m/s and has a rectangular cross section of high and wide, was used in experiments. The flow around the bus model was simulated with ANSYS CFX at wind tunnel conditions. As a result, aerodynamic drag coefficient of the bus model was determined as 0,66 and 0,65 according to results of CFX and experiment respectively after Reynolds number 57000. It is determined that the drag coefficient of the blunt vehicles can be determine by using low speed wind tunnel and Reynolds number independence.

This paper presents the numerical analysis of a controlled auto ignition (CAI), four stroke, single cylinder engine, by using methane fuel. The goal of this study was to determine how exhaust gas recirculation (EGR) rate affects combustion, emission and engine performance. The EGR rates were selected as 27 %, 32 %, 37 %, and 42 % by mass with excess air ratios of 1.0, 1.5, 2.0, and 2.5. An in-cylinder temperature of 570 K was considered at intake valve closing time (IVC) and an engine speed of 1500 rpm was used for all cases. The Computational Fluid Dynamics (CFD) code FLUENT was used for numerical analysis. The numerical modeling was solved by taking into consideration the effect of turbulence, by using the Renormalization Group Theory (RNG) k-? model. The results indicate that increase in EGR rate and excess air ratio have significant effects on in-cylinder pressure, temperature, heat release rate, pressure rise rate, combustion duration, brake work, specific NOx and CO emissions, thermal efficiency and specific fuel consumption. Moreover, CAI combustion resulted in a rapid heat release rate which gives rise to an increase in the pressure rise rate, high temperature value and high level SNOx emission, when EGR rate was low level (up to 32 %) for excess air ratio(?) value of 1 and 1.5. To achieve CAI combustion resulting in low level SNOx emission, the mixture must include an EGR rate of more than 32 % or become leaner.