Amedeo Frilli

Object oriented simulation of longitudinal trair dynamics efficient tools to optimize sustainability and efficiency of railway systems

As a partner of the Tesys Rail Project, the University of Florence has developed an innovative model of the longitudinal railway vehicle dynamics that can be easily adapted to different kind of applications and mission scenarios, ranging from tramways or freight to passenger or even high speed train. The aim of the model is the efficiency and energy optimization of railway systems. A particular attention has been paid to the modularity of the proposed approach and to the possibility of real time implementation on different application targets. The proposed modeling approach reaches a good compromise between the capability of the model to reproduce the behavior of the simulated physical systems and the simplification needed to make the model more general and suitable to represent different technological solutions. In this work, the proposed modeling approach is exposed and, in order to highlight its main features, some benchmark tests are shown.

Regenerative braking in high speed railway applications: analysis by different simulation tools

Technical investigations continuously evaluate the possibility to recover significant amount of braking energy. The application normally involve conventional tramways, characterized by several stops in short-range routes. However, this possibility is becoming more and more attractive also when high-speed trains are considered. In fact, braking energy can be recovered during entry in the station, and delivered later to other trains engaged in starting acceleration. In this work, authors propose an approach based on simplified models performed with object-oriented tools as Modelica or Matlab-Simscape, which easily introduce several advantages in modelling and simulation techniques. The approach has been applied to the preliminary evaluation of one energy storage system installed along a DC line, considering a high-speed train with distributed traction power as the new Italian ETR 1000.

Development and validation of a model for the optimization of regenerative braking of high speed trains

The interest for the energetic optimization of railway systems is constantly increasing due to recent developments concerning Technological Standards and Regulations. A particular attention is usually paid to the coupling between the dynamical behaviour of railway vehicles and the electrical infrastructure, including all the subsystems related to energy distribution and storage. In this research work, the authors propose a newly developed modelling approach for the analysis of the railway vehicle-line system, based on the use of the object-oriented language Simscape that introduces significant advantages with respect to other conventional simulation tools in terms of computational efficiency and modularity. In order to validate the modelling approach, the Italian DC High Speed line, considering a high-speed train with distributed traction power based on the new ETR1000, has been used as a benchmark. The proposed model provides accurate results with a high computational efficiency, proving to be an important tool for the analysis of railway systems. This tool has then be used to perform a preliminary energetic optimization of the considered system).

Tilting Pad Journal Bearing TEHD Analysis: An Innovative Model

Tilting Pad Journal Bearings (TPJBs) are widely used in the turbomachinery field due to their superior dynamical performances, but their operation involves several different physical phenomena. In this research work the authors propose an innovative 3D ThermoElastoHydroDynamic (TEHD) model for the analysis of TPJBs behaviour developed and experimentally validated in cooperation with General Electric Nuovo Pignone: the model is able to perform a nonlinear transient coupled analysis taking into account fluid dynamical, thermal and elastic effects and reaches a good compromise between the accuracy of the results and the computational efficiency.

Braking Energy Recovery in High Speed Trains: An Innovative Model

Modern railway development trend is pushing towards a strong enhancement of the energy efficiency of lines and vehicles, with particular attention to braking energy recovery. In this research work the authors have developed an innovative and numerically efficient vehicle-line coupled model, using the object oriented Simscape language: the model has been validated considering a set of experimental measurements concerning the Italian High Speed train ETR 1000 and has then be used to analyze the feasibility of the application of energy storage systems in high speed application. This analysis has shown that the use of stationary energy storage devices can provide significant energy savings even in high speed applications.

An extended library of models of railway vehicles for fast simulation and optimization of regenerative braking and energy management

As a part of the Tesys Rail Project authors have developed a parametric and computationally affordable model of a railway DC line in order to analyze the complex energetic interactions arising between different travelling vehicles. In order to fully exploit the features of the proposed approach and its capability to investigate complex operating scenarios, the authors have further developed the model by including a wider variety of on-board functionalities and a more extended list of simulated vehicles. In this research work, the authors expose some improvements of a previously developed High Speed train model (based on the ETR 1000) and the development of additional models of older Italian High Speed Trains, such as the ETR 500, which are still in service on Italian High Speed lines.

Development and Preliminary Validation of Efficient 3D Models of Tilting Pad Journal Bearings

This paper mainly focuses on the development of efficient three-dimensional (3D) models of TPJBs, able to contemporaneously simulate both the rotor dynamics of the system and the lubricant supply plant. The proposed modelling approach tries to obtain a good compromise between the typical accuracy of standard 3D models and the high numerical efficiency of simpler and less accurate models. In this work, the whole model has been developed and validated in collaboration with Nuovo Pignone General Electric S.p.a. which provided the required technical and physical data. In particular, the experimental data are referred to a suitable lube oil console system, built at the GE testing center in Massa-Carrara (MS, Italy) for the verification of plant components.

A Tilting Pad Journal Bearing Model for Coupled Fluid Dynamical-Rotor Dynamical Analyses

Turbomachines are continuously developing in order to reach higher levels of speed, power and efficiency and the classical Fixed Geometry Journal Bearings have been replaced by Tilting Pad Journal Bearings to avoid instability phenomena. In this paper, the authors propose an innovative quasi-3D TPJB modelling approach that allows the simultaneous and coupled analysis of the typical phenomena involved in TPJB operations. The authors focused on the accurate analysis of the interactions between the rotor and the lubricant supply plant and on the fluid dynamical effects due to the bearing that cause those couplings, aiming at reaching a good compromise between the accuracy and the numerical efficiency of the model (mandatory to analyze systems with many bearings).The TPJB model has been developed and experimentally validated in collaboration with Nuovo Pignone General Electric S.p.a. which provided the technical data of the system and the results of experimental tests.Copyright