THE JOURNAL OF ENGINE RESEARCH
Year:2016 | Volume:11 | Issue:41|Papers Count:9

Eddy current dynamometers are one of the most important equipment of internal combustion engine test cells in powertrain companies. Failure of rolling element bearings in these assets is a common reason for downtime hours of engine test beds. Insufficient information in this field not only imposes unwanted expenses, but also would result in wrong engine testing data. The purpose of this article is the identification and classification of rolling element bearings failure modes in the eddy current dynamometers. This is an essential research for choosing an appropriate maintenance plan in engine testing laboratories. More than 30 faulty ball bearings of different eddy current dynamometers are collected to study different modes in which the bearings actually fail to operate properly. In addition, metallurgical studies have been applied on the failed parts to specify possible root causes of failure. The dynamometers whose bearings are under study have been employed in different engine testing procedures that an eddy current dynamometer is capable of performing e.g. endurance tests, over-speed tests, etc. so that a diversified collection of modes is available which would happen in any eddy current dynamometer. The recognized cases are then classified to prepare a practical basis for condition monitoring of dynamometers using vibration analysis or other methods.

Premixed combustion concepts like HCCI and PPCI have attracted much attention, since these concepts offer possibilities to reduce engine out emissions to a low level, while still achieving good efficiency. Recently researchers have shown that premixed combustion concepts with two fuels with a large difference in auto-ignition properties can generate a spatial gradient of fuel-air mixtures and reactivity offers improved fuel efficiency and lower NOx and smoke exhaust emissions when compared to conventional diesel diffusion combustion due to longer ignition delay. The increased availability of natural gas in the world has renewed interest in order to realize fuel cost savings and reduce pollutant emissions due low carbon content. Thus, premixed combustion using natural gas as a less reactive fuel and diesel fuel with a higher reactivity fuel warrants consideration. This study presents results from an experimental study of Natural Gas-Diesel premixed operation on a single cylinder diesel engine. After that, a computational study using the CFD software has been conducted to investigate the in-cylinder phenomena in different situations. The results reveal both low NOx and smoke emissions can be achieved in dual fuel PPCI concept in compared to conventional diesel but at the expense of increasing of unburned hydrocarbon emissions.

Ethanol as a renewable and alternative fuel when utilized in homogeneous charge compression ignition (HCCI) has potential to substantially reduce nitrogen oxides (NOx) and particle matter (PM) and can maintain HCCI sustainability. HCCI engine operation is limited between two ringing and misfire regions that too retard and advance combustion phasing highly affect HCCI engine operation, performance and emissions. In this study, a modified 0.3 liter single-cylinder direct-injection diesel engine has used with a fuel port injection system. A study has done on effect of ethanol combustion on engine performance and emission by varying incoming air temperature and fuel/air mixture which focused on the zones near ringing and misfire regions. The results indicate that too retarding combustion phasing makes HCCI combustion unstable that affects combustion temperature lower than normal combustion which result in reducing indicated mean effective pressure and producing higher hydrocarbon (HC) and carbon monoxide (CO) emissions and too advancing combustion phasing generates high peak pressure rise rate with rapid combustion and reduces IMEP but amount of CO and HC is lower in this situation.

With the development of engine technology, modern engine power has been improved a lot. Therefore more precise analysis is of much importance. There is more emphasis put on the research on the design of cooling system. An efficient way to study heat transfer in cooling passage of an engine is CFD calculation. With CFD analysis flow pattern in coolant jacket could be analyzed. In this research the velocity, pressure and heat transfer coefficient distribution in the cooling passage of a 4-cylinder SI engine are computed via CFD code AVL Fire. The main goal of author's work is to investigate the precise cooling. Therefore, the effects of head gasket holes on the flow distribution in the hot spot critical regions of the cylinder head can be seen. Three different schemes are proposed to enhance the flow distribution in cylinder head and finally the results are discussed.

The rotary motion engines have still potentially many advantages over the conventional reciprocating engines. But only the reciprocating engine became the dominant mechanism for engines because of the simplicity of the combustion chamber sealing mechanism. This paper describes the basic concept, design, modeling and analysis of a new rotary engine type, axial vane rotary engine. One of important component in the axial vane rotary engine is cam profile which can affect the dynamic behaviors of engine. Seven cam profiles are simulated and compared kinematically to find an optimum cam profile with minimum velocity, acceleration, jerk and pressure angle to have an axial vane rotary engine with high TBO (Time between Overhaul) with respect to conventional type. In addition, a two-zone, quasi-dimensional model as a simple, fast and accurate model, is developed to simulate engine operating cycle and find the chambers pressure. The parametric modeling of an axial vane rotary engine as a prototype, including main parameters (geometrical and operating) is studied and some design considerations are investigated.

Reducing emissions and fuel consumption have always been a major concern of engine manufacturers. In recent years, strict emission laws and fast reduction of fossil fuel resources have increased this concern. Main purpose of this work is to optimize D87 diesel engine with consideration of parameters such as amount of soot emission, BSFC and maximum pressure of combustion chamber. Effect of pre injection on engine performance has been investigated experimentally. Test is done for four different load points in constant maximum speed which at each load point 3 up to 7 percent of total fuel mass is considered in pilot injection. Results show that BSFC is decreased with increasing of pre injected fuel. From the other side soot emission and maximum pressure of combustion chamber are increased by increasing of pre injected fuel, but both of them are still in an acceptable level so the optimum point is selected based on the minimum BSFC. In all cases minimum BSFC is reached by considering 7 percent of total fuel mass in pre injection which the minimum amount of BSFC is about 194 g/kW.h at 1000 kW.