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Intake noise has become one the main concerns in the design of highly-supercharged downsized engines, which are expected to play a significant role in the upcoming years. Apart from the low frequencies associated with engine breathing, in these engines other frequency bands are also relevant which are related to the turbocharger operation, and which may radiate from the high-pressure side from the compressor outlet to the charge air cooler. Medium frequencies may be controlled with the use of different typologies of resonators, but these are not so effective for relatively high frequencies. In this paper, the potential of the use of multi-layer porous materials to control those high frequencies is explored. The material sheets are located in the side chamber of an otherwise conventional resonator, thus providing a compact, lightweight and convenient arrangement.

In this paper, a methodology for the design process of engine cooling systems is presented, which is based on the interaction among three programs: a code developed for radiator sizing and rating, a 3D commercial code used for the air circuit modeling, and a 1D commercial code used for the modeling and simulation of the complete engine cooling system. The aim of the developed methodology, in addition to ensure the system thermal balance, is the improvement of the design process of the cooling system itself, while shortening the development times, in non-automotive applications. An application to the design of a locomotive engine cooling system is presented. The system designed has been assembled and tested, showing the validity of the methodology, as well as the compliance of the designed system with the initially specified thermo-hydraulic constraints and requirements.

Traditionally, combustion noise in Diesel engines has been quantified by means of a global noise level determined in many cases through the estimation of the attenuation curve of the block using the traditional discrete Fourier transform technique. In this work, the wavelet transform is used to establish a more reliable correlation between in-cylinder pressure (sources) and noise (effect) during the combustion of a new generation 2 liter DI Diesel engine. Then, in a qualitative sense, the contribution of each source intrinsic to the combustion process is determined for four engine operating conditions and two injection laws. The results have shown high variations in both the in-cylinder pressure and noise power harmonics along the time, which indicates the non-stationary character of this process.

In this paper, a numerical model is used to study the influence of several relevant parameters on the behaviour of a turbocharged Diesel engine as an exhaust noise source, with two main objectives: first, determine if it is possible to reduce exhaust noise at the source itself, thus simplifying the task of exhaust system design; and secondly, to asses up to which extent simple linear source models may be used to predict exhaust noise in these engines. The results obtained indicate that, on the one hand, exhaust noise is sensitive to the variation of certain engine design parameters and, on the other hand, that for certain running conditions simple source models may give an acceptable estimation of the actual engine behaviour as a noise source.

The influence of manifold geometry on exhaust noise is studied. First, a linear description of the problem is presented, so that potential relevant factors may be identified. Then a full non-linear simulation is performed, for a simple geometry, in order to check, in more realistic conditions, the ideas obtained from the linear theory. The results indicate that, although some qualitative trends may be obtained from the linear analysis, the role of back-reaction of the manifold on the engine (a non-linear coupling effect) may be determinant.

In modeling an Internal Combustion Engine, the combustion sub-model plays a critical role in the overall simulation of the engine as it provides the Mass Fraction Burned (MFB). Analytically, the Heat Release Rate (HRR) can be obtained using the Wiebe function, which is nothing more than a mathematical formulation of the MFB. The mentioned function depends on the following four parameters: efficiency parameter, shape factor, crankshaft angle, and duration of the combustion. In this way, the Wiebe function can be adjusted to experimentally measured values of the mass fraction burned at various operating points using a least-squares regression, and thus obtaining specific values for the unknown parameters. Nevertheless, the main drawback of this approach is the requirement of testing the engine at a given engine load/speed condition. Furthermore, the main objective of this study is to propose a predictive model of the Wiebe parameters for any operating point of the tested SI engine.