Summary of Work Group 5 Activities

As objective of WG5 (https://smartcats.eu/wg5/), significant progress has been made in the experimental and numerical simulation of various combustion systems, from laboratory to industrial scale.

A review of the topics addressed by the WG5 participants shows that the main areas of interest were related to a broad range of subjects including, but not limited to fuel- injection and pollutant formation, fuel-flexibility and novel combustion technologies, furnace optimization and burner design.

The research efforts have been particularly focused on the development of numerical tools and scale-bridging facilities for MILD and diluted combustion, oxy-condition deployment. Numerical studies mainly looked at turbulence-chemistry interactions approaches for these non-conventional combustion systems. In such regimes, the separation of turbulent and chemical scales vanishes, and standard flamelet-based approaches become inappropriate. Finite-rate based approaches based on Perfectly Stirred Reactor and Partially Stirred Reactor closures have been successfully applied to lab-scale and semi-industrial configurations, in the context of both RANS and LES closures for turbulence description.

Flamelet-generated manifold (FGM) approaches, with appropriate selection of progress variables, have been also proposed with very promising results.

In parallel, significant efforts have been dedicated to the development of reliable and robust reduction procedures of detailed chemical mechanisms, to allow their use in CFD simulations, without significantly compromising the accuracy of the predictions. New and conventional reduction methods were evaluated (PCA & Kriging, DRG-related techniques, CSP …), for the a priori and on-the-fly development of kinetic schemes of several smart energy carriers valid in a wide range of conditions, relevant for turbines, furnaces, engines and co-combustion systems.

At the same time, attention has been devoted to the development of methods for the quantification of uncertainties affecting the prediction of detailed kinetic schemes.

In addition, a detailed evaluation on the error sources for several techniques, employed in combustion systems, including electron-ionization (EI), photoionization (PI) molecular-beam mass spectrometry (MBMS) has been made.

Design and/or optimization and set up of scales bridging facilities for MILD Combustion applications have been the results of strong interaction among action participants, both from research centre and companies and led to the identification of peculiar configuration with high fuel and operational flexibility.