Combustor flow computations in general coordinates with a multigrid method

Abstract

. -A computational approach has been developed and applied to calculate the single phase combusting turbulent flowfields. The approach attempts to strike a reasonable balance to handle two competing aspects of the modeling work, namely, the complicated physical and chemical interactions of the flow, and the requirements in resolving the threedimensional geometrical constraints of the combustor contours, film cooling slots, and circular dilution holes. The algorithm employs the non-orthogonal curvilinear coordinates, the second-order accurate discretizations, a multigrid iterative solution procedure, the standard k-E turbulence model, and a combustion model comprising of an assumed probability density function and the conserved scalar variable formulation. This paper gives an account of the overall computational approach, including recent advances in the solution procedure of the coupled pressure and velocity variables, the 3-D grid generation algorithm, 2-D adaptive grid method applied to recirculating turbulent reacting flows, and theory/data assessments for 3-D combusting flows in a modern annular gas-turbine combustor. Such a numerical approach can be useful in aiding combustor design. Two of the significant ways in which the performance level of aircraft turbine engine have been improved are by use of higher pressure ratio compressors and higher turbine inlet temperatures. While these approaches have the potential of improving the engine performance, they have also resulted in an increasingly hostile environment for the engine combustor and turbine components [I]. The rapidly escalating cost of cut-and-try component development testing efforts directed towards improving hot section durability and aerothermal performance has necessitiated the development o f sophisticated and more fundamentally based combustor analysis methods. This has included the development of turbulent reacting flow models and suitable numerical algorithms, as assessed in Ref. [2]. Recent rapid advances in computer technology have permitted the extension of these computational models to fully 3-D elliptic form suitable for detailed analytical simulation of the internal aerothermal flowfield of conventional