Surface roughness prediction in milling based on tool displacements

In this paper, an experimental device using non-contact displacement sensors for the investigation of milling tool behaviour is presented. It enables the recording of high frequency tool vibrations during milling operations. The aim of this study is related to the surface topography prediction using tool displacements and based on tool center point methodology. From the recorded signals and the machining parameters, the tool deformation is modeled. Then, from the calculated deflection, the surface topography in 3D can be predicted. In recent studies, displacements in XY plane have been measured to predict the surface topography in flank milling. In this article, the angular deflection of the tool is also considered. This leads to the prediction of surfaces obtained in flank milling as well as in end milling operations. Validation tests were carried out: the predicted profiles were compared to the measured profile. The results show that the prediction corresponds well in shape and amplitude with the measurement

A CRS4 spallation Target for ESS Simulations with starccm+V5.0

In this document, we present a series of CFD simulations performed with starccm+V5 to build a sound proposal of windowless channel spallation target for ESS. The simulations increase progressively in complexity. The first simulation is a simple Mercury loop under the effect of a pulsed proton beam. The second one also includes a Hg/vacuum dynamic interface, using the VOF algorithm. The last simulations consider a LBE loop under vacuum subject to the thermal interaction with a proton beam, and is the basis for the proposal to ESS, still using the VOF algorithm. The simulation could be completed in a satisfactory way thanks to the use of a specific sharpening algorithm. This algorithm is explained and commented. The last simulations implementation is also described in details. The final results are shown. They appear very satisfying because the sharpening algorithm performs very well without giving rigidity to the free-surface and because the design elaborated seems a very promising basis for an ESS spallation target

A common description for surface-tension and diffusion in two-component flows

This report tries to develop a common representation for diffusion and surface tension in two components newtonian flows. First, we make some preliminary considerations: (1) the Navier-Stokes equations of a fluid with two immiscible components is derived from the single components equations.In this case, the surface tension arrives from external consideration; (2) we shortly review the Cahn-Hilliard and Allen-Cahn equations describing a phase separation process, the surface-tension being considered as the terminal part of this process; and (3) we report a conservative representation of the surface tension and some of its variants. Second, we reinterprete the conservative form of the single components as also valid for miscible fluids. Making an hypothesis common in diffusion phenomena, we make the surface tension naturally appear from the single phase equations. An anti-diffusive term connected with the surface tension is put in evidence. Compatibility with diffusion is discussed

Memo sulla possibile riconversione della produzione agricola in Sardegna per la generazione di energia da biomassa

Questo breve documento è un’estrema sintesi di un lavoro di ricerca documentale, principalmente su internet, di una decina di giorni, sull’uso della produzione agricola a fini energetici. Piuttosto che riprodurre pagine e pagine di materiale, ho preferito riportare in modo succinto i dati ritenuti più significativi, privilegiando l’esempio esplicativo alla descrizione esaustiva, ricercando una prospettiva funzionale. A questo documento, saranno allegati alcuni testi di riferimento e i link a siti di principale interesse che permetteranno al lettore interessato di avere un adeguato punto di partenza per un eventuale approfondimento dell’argomento

Description of the VOF based pressure algorithm and application to XT-ADS like spallation target

The simulation of Heavy Liquid Metal Vacuum complex interfaces with Starccm+ from CD-Adapco using the Volume of Fluid (VOF) framework requires specifi c care. In a first part, we describe how we managed to deal with the high density ratio and the interface smearing in the context of three different windowless spallation targets. The interface smearing is controlled with a non-conservative condensation term. The second part is dedicated to the individuation of the relevant physical process leading to the interface sharpening and its inclusion in the set of constitutive equations. The methodology used has been to re-derive the VOF equations for momentum and phase transport from the constitutive phase equations. Two candidates for sharpening are individuated: baro-diffusion and surface tension effects. Only baro-diffusion is however likely to have the required strength in the foreseen applications

Progress in the self-similar turbulent flame premixed combustion model

This paper is devoted to premixed combustion modeling in turbulent flow. First, we briefly remind the main features of the Self-Similar Turbulent Flame model that was more extensively developed in a former paper. Then, we carefully describe some improvements of the model. The determination of the turbulent flame velocity is based on the observed self-similarity of the turbulent flame and uses the local flame brush width as a fundamental parameter, which must be retrieved. With respect to the former version, we now derive more rigorously how the density variation has to be taken into account in the width retrieving function. We reformulate the diffusion term as a classical flux divergence term. We enforce the compatibility of the model for the limit of weak turbulence. We include a contracting effect of the source term, thus allowing to give a stationary mono-dimensional asymptotic solution with a finite width. We also include in a preliminary form, a stretch factor, which proves to be useful for controlling the flame behavior close to the flame holder and near the walls. The model implementation in the Star-CD CFD code is then tested on three different flame configurations. Finally, we shortly discuss the model improvements and the simulation results.This research has been funded by the Autonomous Region of Sardinia.4074-4088Pubblicat

Extensions of the SSTF model for applications in which density depends on temperature

This paper is devoted to premixed combustion modelling in turbulent flow. First, we briefly give the main features of the SSTF model and its shortcomings, more extensively developped in a former paper. Then, we carefully describe some improvement of the model. The turbulent flame velocity is based on the observed self-similarity of the turbulent flame and uses the local flame brush width as a fundamental parameter, which must be retreived. We derive more rigorously the way density variations have to be taken into account in the width retreiving fuction. We reformulate the diffusion term as a classical flux divergence. We enforce the compatibility of the model for the limit of small turbulence. We include a contracting effect of the source term, allowing to give a stationnary monodimensional asymptotic solution with finite width. We also include in a preliminary form, a stretch factor, which proves to be useful for controling the flame behaviour close to the flame holder and near the walls. The model implementation in the StarCD CFD code is then tested on three different flame configuration. Finally we shortly discuss the model improvements and the simulation results

Free fall 2D+ simulation with starccm+V4

The aim of this note is to gather some information on the free surface simulations with starccm+ V4 of a 2D+ free falling jet. Two transient simulations are performed aimed at stabilizing the stagnation level where a free falling jet re-connect to the mainstream. While the main objective failed, some useful information on the condensation/sharpening algorithm used is gained

Free surface simulation with starccmV4 Framework and preliminary simulations resume

The aim of this note is to gather some information on how to run free surface simulations with starccmV4

Feasibility study of a CRS4 alternative spallation target for FASTEF

This document gathers some information on the free surface simulations with starccmV4.06 of preliminary versions of a CRS4 spallation target outsider candidate for the XT-ADS or FASTEF spallation target. The initial attempts are shortly illustrated and motivations for the changes are given. Once reasonably satisfied with the geometry, we test a rather simple condensation/sharpening algorithm on rather stiff operating conditions. Several variants, always based on a source/sink term for the light phase, are tested, systematically showing a degradation of the algorithm performances from the original algorithm. Finally, a full 3D loop of a potential candidate as spallation target with a sharp highly transient free-surface and a simplified thermal coupling is described and commented