Session: 03-06 Liquid fuels

Paper Number: 83166

83166 - Validation and Assessment of a Numerical Methodology for Turbulent Liquid Fuel Jets in High-Speed Crossflow 

Environmental concerns have been addressed by various legislative bodies by setting highly ambitious targets to reduce emissions, in particular CO₂ and NOx, for both stationary and aero gas turbine applications. This implies the need to develop more sustainable combustion technologies, such as advanced mixing technologies, which will allow better control on the combustion process to further reduce emissions, by enhancing the uniformity of the fuel-air mixture.

For lean combustion technology, sufficient mixing helps to move away from stoichiometric combustion, the flame temperature of which enormously promotes the production of NOx. Good fuel-air mixing is also essential to avoid fuel-rich pockets, where unburnt hydrocarbon and soot are likely to be produced.  For low emissions gas turbines using liquid fuels, such as diesel, jet in crossflow is one the approaches to achieve efficient liquid jet breakup and evaporation as well as superior mixing characteristics.

In order to develop low emissions fuel spray technologies that use transverse jets, it is important that the current numerical tools have the ability to accurately predict the jet breakup, both primary and secondary, evaporation mechanisms, to properly assess the performance of an injector design. However, because the numerical tools often use model constants that are calibrated with experimental data mostly only applicable to a specific range of operating conditions, a particular test fluid or injection method, it is very challenging to assess the accuracy of the predicted results without further experimental validation. To the author’s best knowledge, the breakup mechanism and the predictive capabilities of the breakup models used to guide the design of novel injectors for fuel transverse jets at elevated pressure and high-speed turbulent crossflow have not been reported in full detail.

Thus, the main focus of this study is to compare and assess the capabilities of the breakup models used in state-of-the-art CFD, including a stochastic approach that relies less on experimental model constants, to predict the spray characteristics of turbulent jets in crossflow at different pressures, gas Weber numbers and momentum flux ratios that are more representative of gas turbine applications. This study will be conducted by using STAR-CCM+. The purpose of this study is also to develop and validate a numerical methodology to guide the design of an experimental test rig on visualising and measuring diesel jet breakup at such simulated conditions. The simulated results will be compared to experimental data to validate and calibrate the breakup models through a parametric and sensitivity study.

Presenting Author: Malika Zghal Cranfield University

Presenting Author Biography: Malika Zghal is currently pursuing a PhD in aerospace sponsored by Siemens Energy at Cranfield University in the United Kingdom. Her PhD project focuses on the development of numerical modelling (CFD) approaches with experimental and numerical analysis to predict liquid-fuel spray characteristics under representative combustor inlet conditions for low-emissions gas turbine combustion systems. She previously graduated top of her class with a Bachelor of Engineering (B.Eng.) in mechanical engineering from Université Laval in Canada. She previously worked as a graduate researcher for hydraulic turbines at Université Laval and more recently in R&D as a CFD analyst for the combustion system for Siemens Energy Canada.

Authors:

Malika Zghal Cranfield University
Xiaoxiao Sun Cranfield University
Pierre Gauthier Siemens Energy
Vishal Sethi Cranfield University