Session: 37-11 Combustors Design Methods
Paper Number: 81784
81784 - Parametric Studies and Simulations of a Hydrogen Micromix Combustor
The use of hydrogen as an alternative fuel in the combustion chamber of an aircraft turbine engine would offer a practical solution to reducing levels of emissions which contribute to atmospheric pollution. In recent years various designs of the basic system component of such an engine have been proposed being described as the hydrogen micromix combustor. This technology requires the design and development of a safe mechanism for hydrogen combustion which avoids auto-ignition and flashback and permits the initial balance and mixing of a hydrogen-air mixture to produce thrust from the combustion of hundreds of miniature low temperature diffusion flames which produce extremely low levels of NOx.
Much research and many articles have been published regarding the design and modelling of this technology using Computational Fluid Dynamics but the fundamental validity of such simulations particularly in terms of the consistency and accuracy of the levels of NOx produced for given numerical methods on systematically finer grids does not appear to have been explicitly addressed.
In this paper a potential geometry and typical operating conditions of such a micromix combustor has been selected for a critical examination of the numerical modelling with particular attention to the levels of NOx predicted. In particular the level of grid independence of the NOx modelling is assessed as well as the variations in NOx levels generated in the march towards steady state solutions for various numerical methods.
Additionally, a series of parametric studies associated with modifications of the basic micro-mix combustor design are explored to verify both the consistency in the numerical methods adopted as well as assessing the impact of such modifications on the overall micromix combustor performance.
Both commercial software (ANSYS-Fluent) and the CIRA software (NExT) developed in-house have been used for these simulations where both the Eddy Dissipation model and the Eddy Dissipation Concept model together with the Jachimowski chemical kinetic model have been implemented to simulate the turbulent chemical kinetics.
Results from the parametric study using different methods for both ANSYS-Fluent and NExT will be presented in terms of temperature, pressure and species concentration distributions, whereas for the systematic assessment of the accuracy and consistency of the NOx predictions on different grids only the results from ANSYS-Fluent using the Zeldovich model for NOx will be presented.
Presenting Author: Ainslie French CIRA Il Centro Italiano di Ricerche Aerospaziali
Presenting Author Biography: Dr Ainslie French received his degree in Maths and Physics at University College North Wales in 1986. He completed an MSc in Aerodynamics in 1988 and a PhD in Computational Fluid Dynam,ics in 1992 at Cranfield College of Aeronautics. He worked in the Aerodynamics division of DERA in the UK from 1990 to 1994 and has been working at CIRA (Il Centro Italiano di Ricerche Aerospaziali) from 1994 to the present.
Authors:
Ainslie French CIRA Il Centro Italiano di Ricerche AerospazialiGiuseppe Mingione CIRA (Centro Italiano di Ricerche Aerospaziali
Antonio Schettino CIRA (Centro Italiano di Ricerche Aerospaziali)
Pietro Roncioni CIRA (Centro Italiano di Ricerche Aerospaziali)
Pier Luigi Vitagliano CIRA (Centro Italiano di Ricerche Aerospaziali)
Mauro Minervino CIRA (Centro Italiano di Ricerche Aerospaziali)
Parametric Studies and Simulations of a Hydrogen Micromix Combustor
Paper Type
Technical Paper Publication