Advanced liner cooling numerical analysis for low emission combustors

The aim to reach very low emission limits has recently changed several aspects of combustor fluid dynamics. Among them, combustor cooling experienced significant design efforts to obtain good performances with unfavourable conditions. This paper deals with simplified 1D and complete 3D conjugate numerical simulations of effusion cooling configurations, performed in the first two years of the European research project INTELLECT D.M. Geometries are derived from typical LPP combustor cooling configurations, which feature low coolant mass flow rate and high pressure losses (compared to typical blade cooling parameters). Results are obtained in terms of local distributions of effectiveness and discharge coefficient. Comparison among simulations allowed to derive useful indications on overall effectiveness behaviour. The configuration simulated in this paper represents a combustor liner with effusion cooling: the plate tested on the CNRS-LCD test rig of Poitiers is composed by two different patterns of effusion cooling. Furthermore, to be the most representative of a combustor chamber, an air flow bleed at the exit of the cold flow is introduced. On the investigated plate SNECMA performed 3D conjugate (coupling fluid/thermal) calculations using a 3D CFD code named N3S-Natur and ABAQUS, a well known 3D thermal code. The codes take into account the effusion cooling area as an homogenous wall described by a permeability, a discharge coefficient for the CFD code and a convective flow (hcon, Tcon) for the thermal one. That means that such simulations are not solving the flow inside each hole. The fluid code also enables to compare the experimental adiabatic effectiveness measurements on this plate, but the aim is before all the overall effectiveness. Conjugate calculations were also performed by means of a procedure employing 1D correlative fluid analysis and 2D metal conduction study. Finally, complete 3D CFD conjugated calculations has been carried out on the plate to verify the validity of assumptions and results obtained with simplified approaches previously exposed.