A detailed investigation into the aerodynamics of a modern gas turbine combustor is
reported in this thesis. The main objectives of this work were to examine the interactions
between the various features of the internal flow field, and between the external and
internal aerodynamics, and to obtain sufficient flow field data for validation of CFD
codes. A new experimental facility was developed to allow optical access for high quality
internal and external measurements of the isothermal flow field in a three sector segment
of an annular gas turbine combustor whose geometry is typical of the combustors in use in
current turbofan engines. A specialised traverse system was designed to enable
measurements of the flow field by a three component Laser Doppler Anemometry (LDA)
system, and a considerable effort was made to maximise the accuracy of the LDA system.
Measurements of three orthogonal mean velocity components and all six Reynolds
stresses were obtained throughout a burner sector of the combustor. A set of data has been
obtained that is sufficiently extensive for use as a benchmark data set for CFD validation.
Measurements in the feed annuli showed that the behaviour of the flow was as
expected. Internal measurements revealed a strong coupling between the flow in the feed
annuli and the flow entering the flame tube through primary and secondary ports.
Differences in the geometries and flow splits in the inner and outer annuli caused
significant differences between the opposed jets inside the flame tube. The initial pitch
angle and axial and radial momentum components of the jets were found to be strongly
dependent on the ports' feed conditions. Differences between the opposed jets, due to
differences in their feed conditions, affected the location of their impingement and the
trajectory of the jet fluid after impingement. The impingement process was also found to
The centre primary jets, which are downstream of the fuel injector, displayed a
dramatically increased sensitivity to their feed conditions, caused by the low pressure in
the recirculation induced by the swirler. This caused the jets to be deflected in opposite
directions, with no impingement. The flow field in the primary zone was thus
substantially altered, with serious implications for the performance of the combustor.
These results also demonstrate the importance of coupling the internal and external flows
in all experimental and computational models.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.