Interstage Disk-Cavity/Brush Seal Numerical Flow Visualization Study

This paper presents work-in-progress results and model developments that are directed towards the computational fluid dynamics simulation of the secondary flow system in a gas turbine engine. Numerical flow visualization results of the 2-D axisymmetric rotational fluid flow (Re=10⁵) in a generic cross section of an interstage turbine cavity are displayed. The core flow is driven by an imposed pressure drop along the vane row of the main flow path. Three interconnected disk cavities separated by a brush seal are located along the secondary flow path. A new computational algorithm was developed in order to predict the flow patterns and leakages for different seal and cavity configurations. The code is based on the numerical solution of the transient laminar Navier-Stokes equations, written in primitive variables and approximated on a nonuniform rectangular collocated grid. The program uses a mass and momentum conservative formulation as well as a set of boundary conditions for pressure and conservation of mass. The pressure solution uses the Poisson equation under a direct implementation procedure. A time dependent Alternating Direction Implicit (ADI) method is also used for the solution of all primitive variables. This integrated computational approach allows the simulation of the rotating disk cavity vortex flow periodic features, as well as their impact on leakage flow and sealing effectiveness. In the present study this approach is used to numerically investigate the flow through the brush. The main purpose of this study is to present an integrated brush seal/disk cavity flow model, to demonstrate the effectiveness of this approach, and to emphasize the necessity for further work in this direction.