Experimental study of accidental industrial LPG releases

International audienceThe objective of the atmospheric dispersion research projects of INERIS are to develop models of flashing releases as encountered in realistic industrial environments. Equivalent source term models exist for flashing release in current long range dispersion models. Several factors can, however, invalidate simplified equivalent source models, especially in the very near field where obstacles can be found. To perform these objectives, INERIS took part in an European project called FLIE (Flashing Liquids in Industrial Environment). In this project, INERIS carried out large-scale experiments with propane and butane releases. The French ministry in charge of Environment also supported INERIS participation which dealt with the modelling of two-phase jets. This paper aims at presenting the large-scale experiments and the main results relative to the rain out observations. The experimental set-up is located in the INERIS test site. It allows performing propane and butane liquid releases at ambient temperature with a regulated pressure from the saturation pressure to 15 bar with an orifice (circular or rectangular shape) of an equivalent diameter from 10 mm to 25 mm. It is possible to realize free jets but also impinging jets by introducing obstacle at a maximum distance of 2 meters from the release point. To develop models requires experimental validation data. Up to now, little of experiments were carried out on a great scale with such a variety of measurements. The results revealed some new points related in particular to the rain-out which are seldom discussed in the literature and which can be useful to develop models of flashing releases. Another important lesson learnt is that pools formed by LPG release jets do not contain liquid exclusively but also a mixture with ice. This has a great influence on the pool evaporation

Characterisation of fuel volatile compounds using a new ionic microsensor

International audienceThe "Intermal combustion engines" project of the DIVA (Diagnostique Industriel et Vehicules Avances) [Industrial Diagnostics and Advanced Vehicle) research centre, funded by Region Picardie, aims to develop a real-time system capable of modifying the operating parameters of a diesel engine so as to optimise its pollutant emissions and fuel consumption

Infrared and ultraviolet properties of the Landau gauge quark propagator

We present a current summary of a program to study the quark propagator using lattice QCD. We use the Overlap and ``Asqtad'' quark actions on a number of lattice ensembles to assess systematic errors. We comment on the place of this work amongst studies of QCD Green's functions in other formulations. A preliminary calculation of the running quark mass is presented.Comment: 7 pages, Contribution to LHP03, Cairn

Improvement of the hazard identification and assessment in application of the Seveso II directive (part II)

National audienceThe Council Directive 96/82/EC of 9 December 1996 on the control of major-accident hazards involving dangerous substances, known as Seveso II Directive, aims at the prevention of major accidents in high risk industries, and the limitation of their consequences for human beings and environment. Although rules are well established to identify maximal hazard potential, there is no recognised method for taking into account, in the assessment of risk level, safety devices and safety management systems implemented by operators. This paper deals with the second stage of a global methodology aiming at better assessing benefits gained from safety devices and safety management systems, through accident scenarios selection. The methodology presented in this paper enables risk assessors and competent authorities to identify Reference Accidents Scenarios (RAS), by taking into account the influence of some safety barriers, in accordance with the Seveso II Directive requirements. This method could help stakeholders involved in the public risk-based decision-making process to evaluate the safety level of high-risk establishments. Since the risk management decisions are based on the risk assessment [12], and since the choices and hypothesis to define the RAS are arbitrary, there is a need to reach a consensus among all the stakeholders to limit the discrepancy in the decision and improve the transparency.La Directive européenne 96/82/EC du 9 Décembre 1982 sur le contrôle des accidents majeurs impliquant des substances dangereuses, connue également sous le nom de Directive Seveso II, a pour objectif la prévention des accidents majeurs dans les sites industriels à hauts risques, et la limitation de leurs conséquences pour les populations et l'environnement. Bien que les règles soient bien établies pour l'identification du risque potentiel, il n'y a pas de méthode reconnue pour la prise en compte, dans l'évaluation du potentiel maximal de danger, des dispositifs de sécurité et des systèmes de gestion de la sécurité mis en oeuvre par les exploitants. Cet article traite de la seconde étape d'une méthodologie générale, qui vise à mieux évaluer les améliorations apportées par les dispositifs de sécurité et des systèmes de gestion de la sécurité, à travers la sélection des scénarios d'accidents. La méthode présentée dans cet article permet aux évaluateurs du risque ainsi qu'aux autorités compétentes d'identifier les Scénarios Accidentels de Référence, qui prennent en compte l'influence de certaines barrières de sécurité, en accord avec les exigences de la Directive Seveso II. Cette méthode pourrait aider les parties prenantes impliquées dans le processus décisionnel de gestion publique basé sur les risques, afin d'évaluer le niveau de sécurité des établissements à hauts risques. Comme les décisions de gestion des risques sont basées sur l'évaluation des risques, et comme les choix et les hypothèses pour définir les Scénarios Accidentels de Référence sont arbitraires, il est nécessaire d'obtenir un consensus parmi les parties prenantes, afin de limiter les divergences dans les décisions et améliorer la transparence

The FLIC Overlap Quark Propagator

FLIC overlap fermions are a variant of the standard (Wilson) overlap action, with the FLIC (Fat Link Irrelevant Clover) action as the overlap kernel rather than the Wilson action. The structure of the FLIC overlap fermion propagator in momentum space is studied, and a comparison against previous studies of the Wilson overlap propagator in quenched QCD is performed. To explore the scaling properties of the propagator for the two actions, numerical calculations are performed in Landau Gauge across three lattices with different lattice spacing $a$ and similar physical volumes. We find that at light quark masses the acti ons agree in both the infrared and the ultraviolet, but at heavier masses some disagreement in the ultraviolet appears. This is attributed to the two action s having different discretisation errors with the FLIC overlap providing superior performance in this regime. Both actions scale reasonably, but some scaling violations are observed

Gluons, quarks, and the transition from nonperturbative to perturbative QCD

Lattice-based investigations of two fundamental QCD quantities are described, namely the gluon and quark propagators in Landau gauge. We have studied the Landau gauge gluon propagator using a variety of lattices with spacings from a = 0.17 to 0.41 fm. We demonstrate that it is possible to obtain scaling behavior over a very wide range of momenta and lattice spacings and to explore the infinite volume and continuum limits. These results confirm that the Landau gauge gluon propagator is infrared finite. We study the Landau gauge quark propagator in quenched QCD using two forms of the O(a)-improved propagator and we find good agreement between these. The extracted value of the infrared quark mass in the chiral limit is found to be 300 +/- 30 MeV. We conclude that the momentum regime where the transition from nonperturbative to perturbative QCD occurs is Q^2 approx 4GeV^2.Comment: 8 pages, 6 figures, 1 table. Talk presented by AGW at the Workshop on Lepton Scattering, Hadrons and QCD, March 26-April 5, 2001, CSSM, Adelaide, Australia. To appear in the proceeding