Turbulence intensity measurements across a NGV cooled cascade with representative lean burn combustor outflow

Significant turbulence levels can be achieved at the exit of modern lean-burn aeroengine combustors, due to the limited interaction between swirling mainflow and liner flows. In this study, hot wire anemometry was exploited to assess the turbulence intensity across a film-cooled NGV cascade, installed downstream of a non-reactive lean burn combustor simulator. The interpretation of the turbulence measurements was improved thanks to the average flow field and pressure results, gathered by five hole probe investigation. The results showed that the swirling mainflow was responsible for very high turbulence intensities on the combustor exit plane. Important turbulence intensities were also found at the NGV exit, due to the conservation of the residual swirling structure and to its interaction with the endwall flows. The effect of nozzle film-cooling injection was also assessed: a limited effect was found, with film-cooling injection generally leading to slightly reduced turbulence intensities.