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In recent years, in order to optimize performance and exhaust emissions of internal combustion engines, the design of auxiliary systems assumed a particular importance especially due to the need to obtain higher efficiency and reduce power losses required by these components. In this sense, looking at the lubrication circuit, it appears important to use solutions that allow to optimize the fluid dynamics of both the ducts and the pump. In this paper a tridimensional CFD analysis of a lubrication circuit oil pump of a modern high-performance engine will be shown. In this particular application there is a variable displacement pump used to optimize the operative conditions of the lubricant circuit in all engine running conditions. This variable displacement pump changes the positions of the ring as a function of the boundary conditions.

In recent years, the need to optimize the performance and reduce exhaust emissions of internal combustion engines has caused the design of the auxiliary (like lubrication and cooling pumps) to assume a particular importance. This is especially due to the necessity to obtain higher efficiency with less expense in terms of work assigned to these organs. With respect to the lubrication circuit, this means the use of solutions that allow the optimization of the fluid dynamics of both the ducts and the pump. This work is based on a simulated analysis carried out on the lubrication circuit of a light duty internal combustion engine, developed by Fiat and equipped with a hydraulic VVT system.

The aim of this paper is the analysis of a Diesel engine lubrication circuit with a tri-dimensional CFD technique. The simulation model was built using Pumplinx®, a commercial code by Simerics Inc.®, developed and optimized for predicting oil flow rates and cavitation phenomena. The aim of this paper is, also, to show that this code is able to satisfactorily model, in a very “economic” way, an unsteady hydraulic system such as the lubrication circuit First of all, an accurate model of a lubrication circuit oil pump will be described. The model was validated with data from an experimental campaign carried out in the hydraulic laboratory of the Industrial Engineering Department of the University of Naples. Secondly, the oil pump model was coupled with a tri-dimensional model of the entire lubrication circuit, in order to compute all the hydraulic resistances of the network and the oil consumption rate of the circuit components

This paper is based on a Research Project of the Department of Mechanical Engineering (DiME) in collaboration with Aprilia, the Italian motorbike manufacturer. In an attempt to simulate the functioning of the cooling plant of the Aprilia RSV-4 motorbike a numerical model was constructed using mono-dimensional and three-dimensional simulation codes. Our ultimate aim was to create a simulation model which could be of assistance to engine designers to improve cooling plant performance, thereby reducing research and development costs. The model allows to simulate the running conditions of the whole cooling circuit upon variations in environmental and running conditions. In particular, the centrifugal pump of the cooling plant was simulated by a 3D commercial software, while the whole circuit was built by a 1D commercial code which allows simulation of all the thermal exchanges and pressure drops in the cooling circuit.

In the last ten year the mechanical power output of car engine increased significantly. This result has been possible especially through new injection systems that brought to an optimization of the combustion (direct injection, common rail) and to an improvement of the turbocharging. Moreover, these technical devices brought a reduction of the exhaust emissions and an increasing of the engine efficiency. In particular, the specific power is increased from 34 kW/liter of 1992 to the 63 kW/liter of 2010. Furthermore, the pressure peaks into the combustion chamber and the fuel injection pressure have been increased to the aim of emission reduction and higher engine efficiency. In this scenario, car manufacturers are following the direction of the engine downsizing that means to have the same engine power by a lower engine displacement.

Euro 6 European legislation emission limits, expected to be introduced around the 2014 timeframe, Lean NOx Trap (LNT) Aftertreatment technology is today considered one the of candidate technology to allow diesel Engine to meet the future Euro 6 limit. The working principle of the LNT is based on its capability to store the NOx engine out during the normal lean (excess of Oxygen) phase operation condition of the Diesel engine. The NOx will be then reduced in a dedicated regeneration phase which consist in creating for relatively short time a rich exhaust gas condition inside the LNT. The LNT regeneration strategy lead to run a Diesel engine with a rich mixture out of the combustion as a Gasoline engine. This can be obtained using advanced air and fuel management. The fuel management implicate the use of delayed injections (after and/or post injections) which can have a direct impact on oil dilution.

Race internal combustion engines are the result of several years of design made to satisfy the growing demand of high specific power. As a result of this increased specific power demand all of the engine components that require lubrication are exposed to a broader range of more extreme operating conditions. Hence an optimized design of a race engine lubricant circuit is becoming much more important, due to the necessity to have its effectiveness with a rational management of its own energy. In this paper, Authors analyse a motorbike high performance lubrication circuit by a simulation methodology, already used and validated for other high performance engine types. It will be illustrated a simulation model, made by mono-dimensional (1D) code, which allows to study all lubricant circuit behaviour, analyzing parameters that are not easy to evaluate experimentally and that, too often, designers don't take into account during engine development.

With the increase of specific power, in development of modern engines, also the demand on the cooling system has significantly increased. CFD analysis reveals the occurrence of localized boiling, since often the measured temperature distribution cannot be explained by convective heat transfer alone [1]. The requirement for highest heat transfer rates has led to the very promising concept of a controlled transition from pure convection to subcooled boiling in the critical thermal conditions [2]. However, computational fluid dynamics is still unable to represent boiling flow, while any boiling based strategy requires a right prediction of heat transfer rates on the coolant surface inside IC engines. Chen's heat transfer model for boiling region [1, 2, 4, 6] is widely used today, to predict and compare the predicted heat transfer coefficients in circular and rectangular ducts with experimental results.

Lean NOx Trap (LNT) catalysts are capable of reducing exhaust NOx emissions from Diesel engines. NOx is stored on the catalyst substrate during the normal engine operation (lean mixture) and is reduced under rich exhaust condition (rich mixture) during the regeneration event. There are different methods to obtain the rich conditions and one of this is the so called “in cylinder” regeneration. This technique is feasible if the engine is equipped with electronic injection system (i.e. Common Rail system), in fact it is possible to obtain rich Air/Fuel ratios conditions using different injection strategies. Generally, one method to obtain the rich condition for the LNT regeneration consists of additional fuel's injection into the engine cylinders while acting at the same time on EGR and Throttle Valve to reduce the intake air flow.

The modern common rail Diesel engines are normally optimised for being fuelled with the commercial Diesel fuel. Consequently, the ECU calibrations are defined to realize the best compromise between performances and emissions. If the engine is fuelled with an alternative biofuel with different characteristics (net heating value, stoichiometric A/F ratio, density, viscosity, etc.) it is clear that the calibration must be modified. Interest in fuels from renewable sources and their use in transportation has grown over the last decade. This is because of their biodegradability, potential improvements in exhaust emissions and benefits on the virtuous CO2 cycle of the earth. This paper demonstrates that it is possible to optimise emissions and performances of a light duty C.R. Diesel engine fuelled with a vegetable derived fuel (Rapeseed Methyl-Ester) pure or blended with commercial Diesel fuel.