Flow Measurements in a Reactive Model of a Gas Turbine Combustion Chamber

Abstract

The results of the investigation of the flow in a transparent (quartz tube) downscaled (≈1:3) model of a lean-premix type gas turbine combustion chamber are presented and discused. The model was tested at atmospheric pressure in reacting conditions; flow measurements were taken by a two-channel fiber-optic laser doppler velocimeter, using Al2O3 seeding of the air flowrate. The measurements cover a wide flow field inside the combustion chamber, including flame development and recirculating regions. Long-time samples (10–20 s) were used in order to achieve a good accuracy in the measurement of average flow conditions over the whole flow field; this involved a limited capability of representation of high-frequency components of turbulence, which could be locally obtained with optimization of the data rate and seeding conditions. Fast measurements were also locally performed where the seeding conditions were favourable. Integral variables and power spectra for reacting conditions show some distinctive aspects for the turbulence structure of reacting turbulent flows in confined spaces. Further measurements cover the outlet throat section of the premix combustor, demonstrating the persistence of a radial flow component on account of wall curvature effects and a certain degree of asimmetry in the inlet velocity distribution.