A new turbomachinery analysis code called SWIFT has been developed
at the NASA Lewis Research Center. SWIFT solves thin-layer Navier-Stokes
equations with the Baldwin-Lomax turbulence model and an explicit
finite-difference scheme. Preconditioning allows the code to be
used for all speed ranges, from incompressible to supersonic flows.
Multiblock capability allows three types of grids to be patched
together to simulate many types of turbomachinery geometries,
including hub and tip clearances. In addition, code users can
analyze multistage turbomachinery by using a steady averaging-plane
approach. This approach uses linearized characteristic boundary
conditions to pass information accurately between the stages.
SWIFT has been validated for an isolated transonic compressor
rotor and used to look at tip clearance flows in detail (ref.
1). The code has recently been validated for the two-stage Space
Shuttle Main Engine fuel turbine. For these calculations, a seven-block
grid with just over one million grid points was used. The calculations
required about 4 hours of CPU time on the Cray C-90 computer at
the NASA Ames Research Center, but they can be run overnight on
a fast workstation. The figure shows colored contours of surface
pressure on the four turbine blade rows. Tip clearances were modeled
for the rotors, and the tip pressure distributions can be seen.
Computed pressure distributions compare well with experimental
data on the stators at midspan and on the endwalls. Computed values
of surface heat transfer also compare reasonably well with experimental
data on the stators and first rotor.
1. Chima, R.V.: Calculation of Tip Clearance Effects in a Transonic
Compressor Rotor. ASME Paper GT-114 (Also NASA TM-107216), 1996.
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Last updated April 29, 1997
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