Cerfacs Enter the world of high performance ...

The 11 December 2020 at 14h00

PhD defense: Quentin MALÉ – “Numerical Investigation of Pre-Chamber Ignition in Internal Combustion Engines”

Marie LABADENS |  Cerfacs, Toulouse - Salle administration by videoconference |  

Abstract :

Homogeneous lean combustion is a great opportunity to reduce Interna Combustion Engine (ICE) emissions (both greenhouse gases and pollutants) if combined with responsible use. Unfortunately, burning lean mixtures and meeting the demands of ICEs is complicated by low reactions rates, extinction, instabilities and mild heat release. There is therefore a need for breakthrough technologies thwarting the adverse effects of lean combustion to leverage lean-burn strategies in ICEs. The Pre-Chamber Ignition (PCI) concept has demonstrated its capabilities to induce very high burning rates enabling ultra-lean premixed mixtures to be burnt efficiently. This is achieved through the creation of multiple highly turbulent jets of hot burnt gases issuing into the main chamber of the engine. However, the optimization of the size of the pre-chamber orifices is something very complex that is not yet clearly understood. Small holes must be used in order to generate enough turbulence in the main chamber, but these small holes can also inhibit the ignition of the main chamber because of too high jet cooling and/or speed. Therein lies the challenge of this research work: how to design the holes connecting pre- and main chambers to maximize burning rates without exceeding the ignition limit?

To answer this question, multiple numerical tools were used: kinetically detailed Direct Numerical Simulation (DNS), Large Eddy Simulation (LES) and zero-dimensional modelling. DNS was used to build precise knowledge on jet ignition. Especially, it helped to understand how the jet injection speed and temperature govern ignition and revealed specific ignition and combustion flame structures. It also allowed to build models to predict the outcome of an ignition sequence. LES was used to study the whole PCI concept in a real engine. It allowed to analyse the flow entering and leaving the pre-chamber, to measure the cooling and quenching effects in the connecting ducts, and to analyse the ignition and combustion processes for both normal and abnormal combustion cases. Finally, a zero-dimensional model has been developed based on a multi-zone approach. It integrates key sub models to account for thermal effects in the ducts and to predict the outcome of the jet ignition attempts in the main chamber. Therefore, it provides a crucial tool to answer the research question by evaluating the result of multiple PCI designs in term of main chamber ignition at a low computational cost.

Keywords: combustion, ignition, internal combustion engine, pre-chamber, simulation


Christine MOUNAIM-ROUSSELLE  PRISME laboratory, Orléans            Referee
Ronan VICQUELIN EM2C laboratory, Paris SaclayReferee
Nicolas NOIRAYETH ZürichMember
Frédéric RAVET Renault, Boulogne-BillancourtInvited member
Thierry POINSOTIMFT, ToulouseAdvisor
Olivier VERMOREL CERFACS, Toulouse Co advisor


Medal of the Academy of Air and Space: 3 CERFACS researchers awarded !

Brigitte Yzel |  11 July 2022

The Air and Space Academy awarded Carlos Pérez Arroyo, Gabriel Staffelbach and Jérôme Dombard with the Vermeil medal 2022, to honor the excellence of their work in the realization of the FULLEST project, the first high-fidelity simulation of an aircraft engine. Thanks to PRACE for awarding the access to the Joliot-Curie supercomputer (GENCI hosted at CEA/TGCC) and to DGAC for the funding of the ATOM project (No 2018-39) led by SAFRAN Tech. FULLEST also benefited from developments done in European projects:  EXCELLERAT (H2020 823691) and EPEEC (H2020 801051).  Read more


CERFACS |  4 July 2022

CERFACS will participate to the Paris meeting dedicated to the memory of Roland Glowinski from July 5th to 7th. Thierry Poinsot will present the advances of HPC in the field of energy and combustion. Roland Glowinski was CERFACS direcfor for 3 years in the 90s and largely shaped present activities of our research center.Read more