ASSESSMENT OF TURBULENCE MODELING FOR ENGINEERING PREDICTION OF SWIRLING VORTICES IN THE NEAR BURNER ZONE

Measurements and computations of a number of isothermal swirling flows are reported. The focus is on two categories of swirling flows: high confinement flows in geometries representative of gas turbines and low confinement flows encountered in industrial and experimental furnaces. The flow geometries consisted of a solid-body vortex generator, a burner quarl, and a cylindrical furnace. The measurement techniques utilized are discussed, with emphasis on measurement errors. In order to identify the flow features that the computer models are expected to predict, the physics of the flows is treated in detail. In the finite difference computations, three models of turbulence were tested: a Reynolds stress model (RSM), an algebraic stress model (ASM), and the k-ε model. Attention was paid to numerical related errors, and an effort was made to minimize the effect of numerical diffusion. A major conclusion is that reliable predictions of swirling vortices that were originally in solid-body rotation can be made, if fine numerical grids are used in conjunction with the QUICK method and either the RSM or the ASM. In terms of the overall flow structure, no substantial differences between the RSM and ASM predictions were observed. In the solid-body-rotation flows analyzed, the transport of the Reynolds stresses was of little importance. © 1990.