Joint Experimental and numerical sTudy of H2 Plasma-Assisted Combustion – JETHPAC

A major challenge for our society is to ensure access to reliable energy with low impact on the climate and the environment. To this end, sustainably produced hydrogen (H2) is an alternative to the fossil fuels used today, emitting carbon dioxide. However, the use of H2 as a fuel requires the adaptation of current combustion chambers in order to maximise efficiency, limit the emission of nitrogen oxides (NOx), and ensure safety. NOx emission regulations require the use of lean or ultra-lean premixed combustion for H2, which raises ignition and flame stability issues. The objective of this project is to develop the use of plasma discharges in H2 mixtures, an excellent candidate to i) guarantee a timely ignition after H2 injection in the combustion chamber, and ii) control combustion instabilities.
Over the last twenty years, Non-Equilibrium Plasma (NEP) discharges including Nanosecond Repetitively Pulse Discharges (NRPD) have been studied by the scientific community to control combustion in hydrocarbon-air mixtures. Many works now demonstrate their ability to sustain lean combustion and mitigate combustion instabilities. NRPD can also be used to ignite a mixture effectively without large heat deposition, by generating reactive radicals that will initiate the oxidation of the fuel at low temperature. This ensures smooth and reliable ignition of combustible mixtures, without too high pressure rise and risk of detonation.
Although the NRPD efficiency has been evidenced for hydrocarbon mixtures, their use in complex systems fully or partially fed with H2 is yet to be investigated. Based on experiments conducted at ETH Zürich and numerical simulations conducted at CERFACS, both fundamental and practical research questions will be investigated in this project. First, the effects of NRPD discharges in H2-containing mixtures will be established in a canonical channel flow configuration. Based on this knowledge, we will design the discharge parameters in order to optimise the ignition by radical generation from the plasma. We will then study both experimentally and numerically the effects of NRPD discharges in a realistic complex configuration, close to an industrial system. Both the smooth ignition and the control of combustion instabilities will be investigated. The 3-dimensional computations of the configurations will provide essential information for the understanding of the associated physics. New phenomenological models for plasma physics will be derived to make the computation of such complex configurations possible, overcoming the huge cost of fully coupled plasma-combustion simulation.
This research project will provide knowledge for the design of NRPD systems, leveraging the combustion of hydrogen in lean regimes to allow the use of this carbon-free fuel in combustion systems. For this reason, the project has the potential of a very strong impact on the energy production and transport industry.