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Shock absorbers and damper systems are important parts of automobiles and motorcycles because they have effects on safety, ride comfort, and handling. In particular, for vehicle safety, shock absorber system plays a fundamental role in maintaining the contact between tire and road. Generally, to assure the best trade-off between safety and ride comfort, a fine experimental tuning on all shock absorber components is necessary. Inside a common damper system the presence of several conjugated actions made by springs, oil and pressurized air requires a significant experimental support and a great number of prototypes and test. Aimed to reduce the design and tuning phases of a damper system, it is necessary to join these phases together with a numerical modelling phase. The aim of this paper is to present the development of a mono-dimensional (1D) model for simulating dynamic behaviour of damper system.

A numerical methodology to simulate the high pressure spray evolution and the fuel-air mixing in diesel engines is presented. Attention is focused on the employed atomization model, a modified version of the Huh and Gosman, on the definition of a turbulence length scale limiter and of an adaptive local mesh refinement technique to minimize the result grid dependency. All the discussed models were implemented into Lib-ICE, which is a set of libraries and solvers, specifically tailored for engine simulations, which runs under the open-source CFD technology OpenFOAM®. To provide a comprehensive assessment of the proposed methodology, the validation procedure consisted into simulating, with a unique and coherent setup of all models, two different sets of experiments: a non-evaporating diesel fuel spray in a constant-volume vessel with optical access and an evaporating non-reacting diesel fuel spray in an optical engine.

The paper investigates the variation of the mass of the fuel injected with respect to nominal conditions in Common Rail injection systems for Diesel automotive applications. Two possible operating conditions have been considered: the consecutive injection of two injectors and the multiple shots of the same injector in the same engine cycle. An integrated experimental and numerical methodology has been used. Several experimental information were available in terms of instantaneous rail and pipe pressure and mass flow rate at different conditions. The 1D numerical model of the whole injection system was useful in addressing the questions remained unresolved in the post-experiments analysis. The experimental results show that injector performances are more related to pressure oscillations in injector connecting pipe rather than inside the common rail.