Computational methods for modelling port flows in gas-turbine combustors

Abstract

The objective of the present paper is to describe a computational technique which has been developed to allow the detailed geometry of the air-admission ports to be included in computational fluid dynamic studies of gas-turbine combustors. As CFD modelling of combustors continues to improve, it is likely that it will become commonplace to consider complete geometry descriptions of combustors (i.e. external as well as internal) in associated flow calculations, rather than carry out separate calculations, as is more usual currently. It will therefore be both necessary and desirable to include in the calculation the various geometrical features used in port design to control air admission and overall flow splits, (e.g. radiused/plunged/chuted holes, splitter plates, etc.). This requires modifications to standard mesh generation practices which are outlined and demonstrated here. As an illustration of the success and capabilities of the current method, flow field calculations are presented which contrast the changes in flow-split (as a consequence of discharge coefficient changes) and flow-patterns which are predicted when port geometry is varied from a plain hole to a plunged/chuted hole typical of some current designs.