Adiabatic Effectiveness and Flow Field Measurements in a Realistic Effusion Cooled Lean Burn Combustor

Abstract

Over the last ten years there have been significant technological advances toward the reduction of NOx emissions from civil aircraft engines, strongly aimed at meeting stricter and stricter legislation requirements. Nowadays, the most prominent way to meet the target of reducing NOx emissions in modern combustors is represented by lean burn swirl stabilized technology. The high amount of air admitted through a lean-burn injection system is characterized by very complex flow structures such as recirculations, vortex breakdown and precessing vortex core, that may deeply interact in the near wall region of the combustor liner. This interaction makes challenging the estimation of film cooling distribution, commonly generated by slot and effusion systems. The main purpose of the present work is the characterization of the flow field and the adiabatic effectiveness due to the interaction of swirling flow, generated by real geometry injectors, and a liner cooling scheme made up of a slot injection and an effusion array. The experimental apparatus has been developed within EU project LEMCOTEC and consists of a non-reactive three sectors planar rig; the test model is characterized by a complete cooling system and three swirlers, replicating the geometry of a GE Avio PERM (Partially Evaporated and Rapid Mixing) injector technology. Flow field measurements have been performed by means of a standard 2D PIV (Particle Image Velocimetry) technique, while adiabatic effectiveness maps have been obtained using PSP (Pressure Sensitive Paint) technique. PIV results show the effect of coolant injection in the corner vortex region, while the PSP measurements highlight the impact of swirled flow on the liner film protection separating the contribution of slot and effusion flows. Furthermore an additional analysis, exploiting experimental results in terms of heat transfer coefficient, has been performed to estimate the net heat flux reduction (NHFR) on the cooled test plate.

Study of an effusion-cooled plate with high level of upstream fluctuation

“…However, the analysis to link the turbulent flow structures to the ACE performance was limited. Similar research was done by Andreini et al [19] using the PSP technique.…”

The effect of effusion holes inclination angle on the adiabatic film cooling effectiveness in a three-sector gas turbine combustor rig with a realistic swirling flow

“…Results of Figure 9 highlight deep modifications in the flow field varying the coolant injection angle and strong interaction phenomena near the wall between the mainstream and the cooling flows. A different extension of the investigation area was achieved for the two configurations, both covering however the region As already shown in [28], two well-distinct counter rotating vortices are generated by the 30 As a general result, the 90 • perforation tends to lift up the swirler jet, reducing its opening angle and As expected, the highest film covering is achieved by the geometry with the lower inclination angle, where the coolant slant injection is capable to limit jet penetration and to take benefit from superposition effects. The high resolution color maps obtained allow to appreciate the different shape of coolant wall traces produced by each jet.…”

“…For further information, an extensive description of the technique operating principles and the experimental procedure are reported in previous works conducted by the authors [37] [28].…”

Prediction of Liner Metal Temperature of an Aeroengine Combustor with Multi-Physics Scale-Resolving CFD

“…Additionally, it is characterized by lower weight and complexity compared to double-wall schemes, in addition to being less prone to dust clocking. This cooling technique has been widely investigated, both experimentally and numerically, on flat plate, standard mainstream conditions [ 5 , 6 , 7 , 8 ], as well as under the influence of swirling flows [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”