Session: 04-12: Ignition I

Paper Number: 79181

79181 - Effect of Strong Azimuthal Swirl on Ignition and Light-Around in an Annular Combustor 

The airworthiness of an aircraft is highly dependent on its ignition and relight capability.  However, the ignition dynamics of annular combustors are only beginning to be understood due to the complex transient processes involved, the computational methods and resources required and the development of annular combustion facilities with sufficient access for advanced measurements.  In recent years, laboratory annular combustors have been conceived to study this highly transient process. So far, laboratory-scale combustors have used simplified geometries which do not reflect the more complex designs of real engines.  For instance, the presence of dilution holes used in Rich-Quench-Lean staging introduces more complex flow fields in the combustion chamber that can significantly alter the flame stability, ignition, and light around times.  A collaborative effort between SAFRAN Helicopter Engines and the Norwegian University of Science and Technology (NTNU) led to the construction of an atmospheric annular combustor which closely resembles an actual working engine, known as the SAFRAN spinning combustor.  A modified annular test bed has been developed with fuel injectors positioned in a manner to promote a strong mean azimuthal flow, incorporate a perforated combustor backplane for cooling, and a circumferential distribution of dilution ports downstream of the main flame zone.  This enabled independent control of the injector equivalence ratio and global equivalence ratio.  It is found that careful selection of the fuel ratio between adjacent fuel injectors can significantly improve the ignition limit. High-speed imaging and photomultiplier measurements were obtained to characterise the ignition dynamics and light-round times for different operating conditions.  Large-Eddy Simulations were also performed and show good agreement with the measured light-round times.  A staged combustion system was implemented to obtain more realistic behaviour of a real engine leading to the observations of dominant flame branch propagation and evidence of each flame serving as a pilot for next flame downstream.

Presenting Author: Yi Hao Kwah Norwegian University of Science and Technology

Presenting Author Biography: Yi Hao obtained his Master of Engineering at the National University of Singapore, and Diplôme d'ingénieur at École Centrale Paris in 2018. Joining the ANNULIGhT Marie Sklodowska Curie ITN European project as a PhD candidate, Yi Hao has been working under Professor James Dawson at the Norwegian University of Science and Technology (NTNU) on combustion dynamics in annular combustors. In collaboration with SAFRAN Helicopter Engines, he is currently involved in the experimental investigation of ignition and lean blow-off phenomena of a laboratory-scale combustor developed using spinning combustion technology.

Authors:

Yi Hao Kwah Norwegian University of Science and Technology
Pasquale Walter Agostinelli Safran Helicopter Engines - CERFACS
Stéphane Richard Safran Helicopter Engines
Gorka Exilard Safran Helicopter Engines
Stéphane Pascaud Safran Helicopter Engines
Laurent Gicquel CERFACS
James Dawson Norwegian University of Science and Technology