THE JOURNAL OF ENGINE RESEARCH
Year:2011 | Volume:7 | Issue:24|Papers Count:6

Nowadays, engine oils have various functions, which one of the most important of them is the lubrication of different parts in the engine, for reducing the rate of the friction and the wear. Oil properties are mainly a result of additives, which are added to the oil to improve requirement properties. Recently, nano-particles are also appeared as a new kind of additives, due to their special properties.The purpose of the present research is surveying the amount of the ability of nano-particles and it is a kind of the functionality to improve anti-wear properties and the heat-conduction ability and controlling developed variations of the engine oil, on its properties including: the viscosity, the pour point and the flash point. For this purpose, carbon nano ball particles, by using the planetary ball mill, were dispersed inside the Behran Pishtaz engine oil, SAE 20W50. Then, tests were done for investigating mentioned properties. Obtained results showed that the thermal conductivity coefficient of the oil containing carbon nano ball particles with 0.1wt%, increased about 18 percent with respect to the base oil. Also, upon results of the four ball test, the amount of the wear, in the oil contains nano-particles reduced 5 percent with respect to the oil without nano-particles.

In internal combustion engines, crankshafts turn in a wide range of angular velocities under the effect of impact forces coming from pistons by connecting rods. The crankshaft is very susceptible to the vibration due to forces applied on it. Therefore, it is necessary to study the dynamic behavior of the crankshaft.The purpose of this paper is the system identification by determining the modal model of a crankshaft with both theoretical and experimental methods. The crankshaft modeling and the modal analysis are performed in a finite element software. Then, results are validated by modal testing.

The piston scuffing is a major failure of an internal combustion engine. This failure occurs due to loss of the oil film between the piston and the cylinder liner. The piston scuffing investigation by the acoustic emission (AE) method is a new study. Because this failure occurs randomly, it is an online detection which is very difficult. The goal of this paper is to study the ability of the AE method to be applied to the piston scuff detection. In addition record of the AE signal behaviour, before and after the piston scuffing is another new purpose. To this order, in an experimental set-up, two AE sensors was installed on the cylinder head and the engine block of a diesel engine. We know that the blow-by is directly affected by the piston scuffing failure. Therefore, it was measured as a base parameter. The creation of intended piston scuff conditions is very difficult. Therefore, a special test was designed to make it artificially. Results show that the best AE parameter for the piston scuff detection is the AE root mean square and the AE energy. Based on the present method, we can find the location of the event in the cylinder head or in the engine block.

This paper investigates the high cycle fatigue behavior of the AZ91 magnesium alloy. The feasibility study of replacing this alloy with the A356 aluminum alloy for a diesel engine cylinder head is discussed. For this purpose, the AZ91 alloy was casted in a permanent mold and the microscopic examination with optical and scanning electron microscopes (SEM) and mechanical tests include tensile, hardness and high cycle fatigue tests were performed on samples which were prepared based on standards. Results are compared to the A356 aluminum alloy. High cycle fatigue tests were carried out at a stress ratio (R) of -1 and a frequency of 50 Hz at room temperature in the air. The microscopic investigation demonstrates that the microstructure composed of alpha and beta (Mg17 Al12) phases. Fatigue test results show that the fatigue strength of the AZ91 alloy is lower than the A356 alloy, but still in the range of required values for the application in cylinder heads.

Controlling of the fuel injection, including the spray structure and injection timing has a significant impact on the engine performance, especially the formation of pollutants. In this study, a computational fluid dynamics software (AVL Fire) has been used to simulate the start time of the fuel injection in diesel engines and its effect on the soot formation rate. Results show that if the start angle of the fuel injection approaches the TDC, the maximum soot formed will be increased. Also, the amount of the remained soot is increased. Mixing of the fuel and the air cannot be completed as the start angle of the fuel injection gets closer to the TDC, because of increasing the combustion chamber pressure and so decreasing the ignition delay, as a consequent, the rich mixture volume increases and leads to more soot formations. Although that is better to the inject fuel earlier (far from the TDC), but considering other effective parameters on the engine performance, like the ignition delay, produced power, it has been concluded that lower soot formation can not be an advantage by itself.

In this research, the conventional internal combustion engine system in a samand vehicle is replaced by a hybrid electric-fuel cell system. The samand vehicle is then modeled in the ADVISOR software, considering both systems. For modeling, the body structure and wheels models as well as their corresponding parameters are added to the software. For both cases, simulation results such as the fuel consumption and the system efficiency in various driving cycles are studied and compared together. Results show that in the hybrid electric-fuel cell vehicle beside the reduction of the fuel consumption, the efficiency increases with zero exhaust emission pollutant gases. Also, the vehicle could challenge with the internal combustion vehicle in issues such as performance parameters, the velocity, the acceleration and the gradeability.