Frederic Ravet

Frederic Ravet
Renault · Mechanical division

Doctor of Engineering

About

44
Publications
7,864
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364
Citations
Introduction
Frederic Ravet currently works at the Mechanical division, Renault. Frederic does research in fluid dynamic for combustion, lubrication, cooling (...) applications

Publications

Publications (44)
Preprint
Full-text available
This paper presents a multi-chamber, multi-zone engine model to predict the ignition of a lean main chamber by a pre-chamber. The two chambers are connected by small cylindrical holes: the flame is ignited in the pre-chamber, hot gases propagate through the holes and ignite the main chamber through Turbulent Jet Ignition (TJI). The model original f...
Article
Full-text available
This work uses multiple three-dimensional Direct Numerical Simulations (DNSs) to i) investigate the ignition process of a cold lean premixed mixture at atmospheric conditions by a jet of hot burnt gases that may be cooled before injection ii) evaluate models able to predict the outcome of such a scenario in terms of ignition. Understanding and bein...
Article
Full-text available
Using homogeneous lean mixtures is an efficient way to reduce fuel consumption and pollutant emissions in internal combustion engines. However, lean combustion requires breakthrough technologies to induce reliable ignition and fast combustion. One of these technologies uses pre-chamber to create multiple hot turbulent jets and provide ignition site...
Article
For engine knock prediction, surrogate fuels are often composed of iso-octane and n-heptane since they are the components of the Primary Reference Fuel (PRF). By definition, a PRF has no octane sensitivity (S = RON-MON). However, for a commercial gasoline fuel holds RON > MON and therefor S > 0. More complex surrogates are Toluene Reference Fuels (...
Article
Full-text available
Big Challenges on Joliot-Curie - Before it goes in full production, a series of Grand Challenges – large scale simulations from academic and industry research – were carried out on Joliot-Curie supercomputer, from June to September 2018, to check that the system is functioning properly. These Grand Challenges represent a unique opportunity for sele...
Article
Cycle-to-cycle variations are important to consider in the development of spark-ignition engines to further increase fuel conversion efficiency. Direct numerical simulation and large eddy simulation can predict the stochastics of flows and therefore cycle-to-cycle variations. However, the computational costs are too high for engineering purposes if...
Article
Following the resonance theory by Bradley and co-workers, engine knock is a consequence of an auto-ignition in the developing detonation regime. Their detonation diagram was developed using direct numerical simulations and was applied in the literature to engine knock assessment using large eddy simulations. In this work, it is analyzed if the deto...
Chapter
In order to increase the efficiency of the engine and reduce emissions, right sizing plays a predominant role. Validation of turbulent combustion in engine environment using numerical tools is even more challenging. For better understanding of the thermodynamic and chemical behaviour of gas, a proper CFD models set-up should be used to represent tu...
Article
Engine knock is an important phenomenon that needs consideration in the development of gasoline-fueled engines. In our days, this development is supported using numerical simulation tools to further understand and predict in-cylinder processes. In this work, a model tool chain which uses a detailed chemical reaction scheme is proposed to predict th...
Chapter
In this chapter an experimental and numerical simulation were carried out for diesel spray to investigate its characteristics over a wide range of pressure. It would be helpful to predict the spray behavior such as penetration length, atomization, droplet distribution and spray angle for different pressure differences, covering low to high injectio...
Conference Paper
Full-text available
Fuel properties have a major impact on engine knock and therefore need to be considered in detail in spark ignition engine simulations. In our method, the auto-ignition and emissions are calculated based on a new reaction scheme for mixtures of iso-octane, n-heptane, toluene and ethanol (ETRF). Surrogates can be formulated with close agreement to t...
Conference Paper
Full-text available
Fuel properties have a major impact on engine knock and therefore need to be considered in detail in spark ignition engine simulations to find the knock limit spark advance. In our method, the auto-ignition and emissions are calculated based on a reaction scheme for mixtures of iso-octane, n-heptane, toluene and ethanol (ETRF) that allows for a fle...
Conference Paper
The current trend of downsizing used in gasoline engines, while reducing fuel consumption and CO2 emissions, imposes severe thermal loads inside the combustion chamber. These critical thermodynamic conditions lead to the possible auto-ignition (AI) of fresh gases hot-spots around Top-Dead-Center (TDC). At this very moment where the surface to volum...
Conference Paper
Full-text available
Soot modeling is key issue in the design process of a Diesel combustion chamber. Close future Euro-peans standards evolution will be only on the mass emissions but also on size particles. Consequently, be able to predict size particles at the engine out is crucial for current combustion chamber developments. In addition, pollutants emission Europea...
Article
This paper is focused on the experimental and numerical investigation of tumble motion on a single cylinder optical engine on three important parameters like engine load conditions, engine speed and level of tumble. Experiments are conducted in an optical engine and the velocity fields are measured with the aid of advanced particle image velocimetr...
Article
Full-text available
The global objective of this work is to show the capabilities of the Eulerian–Lagrangian spray atomization (ELSA) model for the simulation of Diesel sprays in cold starting conditions. Our main topic is to focus in the analysis of spray formation and its evolution at low temperature 255 K (-18°C) and nonevaporative conditions. Spray behavior and se...
Article
The main objective of this study is to determine the appropriate boundary conditions for the distribution of droplet sizes, speed of the fuel settling at the nozzle of the injector and droplet penetration by numerical simulation using STARCD for a 3-holes injector of ULC-GE. In this study, the Eulerian-Lagrangian approach has been used to model the...
Article
It is the aim of this paper the evaluation and validation of the Eulerian-Lagrangian Spray Atomization (ELSA) model implemented in a CFD code by Renault. ELSA is an integrated model for capturing the whole spray evolution, particularly including primary break-up and secondary atomization. Two-dimensional simulations have been performed during the s...
Article
Full-text available
Two-stroke engines have dropped out of the automobile market for a long time due to severe drawbacks. Unfortunately, the comparison with the performances of four-stroke engines was not in favour of two-stroke ones. Nevertheless, the needs of a more compact engine with a better ratio of the mass and size versus power motivated research efforts at th...
Article
Turbulence and combustion inside a compression machine, experimentally studied by Guibert et al. [Flow Turbulence and Combust. 84(1): 79–85, 2010], are simulated to get some insight on flow-physics and ignition scenarios of a reactive-gas mixture pushed by a piston through a turbulence-grid, to be compressed in a 55 cubic-centimeter volume. Large E...
Article
Full-text available
Many approaches have been used to simulate the spray structure especially in modelling fuel sprays, i.e., Eulerian, Lagrangian, Lagrangian-Eulerian, Eulerian-Eulerian and Eulerian-Lagrangian approaches. The present study uses an Eulerian-Lagrangian spray atomisation (ELSA) method which is an integrated model for capturing the whole spray evolution...
Conference Paper
Full-text available
During the last fifteen years, Computational Fluid Dynamics (CFD) has become one of the most important tools to both understand and improve the diesel spray development in Internal Combustion Engine (ICE). Most of the approaches and models used pure Eulerian or Lagrangian descriptions to simulate the spray behavior. However, each one of them has bo...
Article
CNG is one of the most promising alternate fuels for passenger car applications. CNG is affordable, is available worldwide and has good intrinsic properties including high knock resistance and low carbon content. Usually, CNG engines are developed by integrating CNG injectors in the intake manifold of a baseline gasoline engine, thereby remaining g...
Article
The introduction of alternative fuels is crucial to limit greenhouse gases. CNG is regarded as one of the most promising clean fuels given its worldwide availability, its low price and its intrinsic properties (high knocking resistance, low carbon conten). One way to optimize dedicated natural gas engines is to improve the CNG slow burning velocity...
Article
Full-text available
Probability Density Function (PDF) is often selected to couple chemistry with turbulence for complex reactive flows since complex reactions can be treated without modeling assumptions. This paper describes a preliminary investigation into the use of the particles approximation of this transport equation approach applied to diesel combustion. The mo...
Conference Paper
Turbulent combustion in internal engines is known to cover a wide range of regimes and flame topology. Engine turbulent combustion modeling should account for these various regimes observed, as auto-ignition, premixed, partially premixed or diffusion flames. The corresponding reaction zones are controlled by spray evaporation, and vapor fuel turbul...
Conference Paper
A modeling study of benzene formation was performed in five low-pressure, rich, laminar premixed flames with acetylene, ethylene, propene, benzene and heptane as fuels. Three published detailed reaction mechanisms were tested against molecular beam mass spectrometry (MBMS) species profiles for each flame. Differences between the three mechanisms we...
Article
Some assumptions have to be made to deal with combustion and aerodynamical phenomena simultaneously. We propose a turbulent combustion model where we consider a one step reaction for chemical modelling. Consequently, only two variables are sufficient to describe the problem. In fact, the combustion can be characterized by the consumption of one of...
Article
Some assumptions have to be made to deal with combustion and aerodynamical phenomena simultaneously. We propose a turbulent combustion model where we consider a one step reaction for chemical modelling. Consequently, only two variables are sufficient to describe the problem. In fact, the combustion can be characterized by the consumption of one of...
Article
The ECFM CLE-H is a new approach developed by CORIA [1] [2], [3] to simulate the different phases of Diesel combustion; auto-ignition, premixed and diffusion flame burning. The original proposal was based on two modelling for the two flame structures: premixed and diffusion flame. Particular emphasis was put on improving modelling for the diffusion...

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