Fluid-solid heat transfer coupling
This thesis documents the application of a computer code developed by the author
which makes possible the coupling of heat transfer between fluid and solid thermal
models. The code was written using FORTRAN and couples the commercial
computational fluid dynamics (CFD) software FLUENT with the Rolls-Royce finite
element analysis program, SC03.
The thermal modelling of a solid domain bounded by a fluid typically uses heat
transfer correlations to define the heat flux at those boundaries. Considerable
engineering judgement is required to appropriately select and apply these
correlations, so that they accurately model the flow and geometry being considered.
The objective of the coupling code is to replace the correlations with a CFD model of
the fluid. The coupling is achieved by extracting metal temperatures determined from
the finite element solver, using them to define CFD boundary conditions, and passing
heat fluxes from the resulting CFD solution back to the finite element model. The
finite element model then solves the newly defined problem and the process is
repeated until a converged solution is obtained.
The coupling code was evaluated through its application to two test cases. The first
was an axisymmetric representation of a compressor stator well rig, the experimental
apparatus or which comprised a two stage axial compressor, driven by a single stage
axial turbine. The coupling code was used to model a temperature transient generated
in the rig by injecting liquid nitrogen into the mainstream annulus, upstream of the
compressor stages. For the second test case, an industrial application was chosen
with real engine geometry. Using an axisymmetric finite element whole engine
model of the Rolls-Royce Trent 500 aero-engine the code was employed to couple
both axisymmetric and three dimensional representations of the fluid domain
surrounding the pre-swirl system. Following the successful completion of these two
test cases, the coupling code (now known as SC89) was production released by
Rolls-Royce in July 2004 and is now available to their engineering community, as a
design tool worldwide.