Engineers
from Stanford University, Honeywell International
and ANSYS are working together with simulation
software to create more energy-efficient aircraft engines at lower costs.
As demand grows
for increased gas turbine efficiency, engine manufacturers are challenged with
creating designs that operate at higher temperatures. But that becomes a
significant challenge as temperatures approach the melting point of some engine
component material. A well-established method for maintaining turbine blade
temperatures at acceptable levels is to employ “film-cooling,” a technique in
which cooler, compressor-discharge air is detoured around the combustor then
ejected from precisely-machined holes placed over the surface of the turbine
airfoil. Excessive use of compressor air for turbine film cooling can, however,
reduce engine efficiency.
Historically,
film-cooling-hole-placement on turbine airfoils has been optimized by elaborate
experiments, sometimes necessitating engine testing. For decades, research
engineers have been developing computer simulations of film cooling geometries
with the ambition of reducing – if not eliminating – the need for expensive,
time-consuming rig testing.
Stanford, with
support from Honeywell and ANSYS, is performing a new type of
testing with 3-D magnetic resonance velocimetry to measure the velocity and
concentration field in a test section. These methods measure the turbulent
interaction of crossflow jets with the main flow, for a variety of jet
configurations and orientations. These data sets provide an important benchmark
against which the large available range of ANSYS turbulence models and
computational methods can be compared. The objective is to develop validated
models, methods and best practices for prediction of film cooling.
"This is
the first time that an engineering software company has supported an extensive
test series like this, and it illustrates the commitment of ANSYS to the
continued upgrade of the turbulence models in ANSYS computational fluid
dynamics solutions," said John K. Eaton, the Charles Lee Powell Foundation
professor in Stanford’s School of Engineering. “Our combined efforts are aimed
at validating the turbulent mixing models in these tools over entire complex
flow fields, something that has never been done before. Conducting this testing
over a wide range of film cooling conditions provides a comprehensive test of
the predictive capability."
“At
30,000 feet in the air, there’s little margin for error,” said Brad Hutchinson, global
industry director for industrial equipment and rotating machinery at ANSYS. “By always focusing on solving the most complex
problems – like the thin film cooling challenge Honeywell and Stanford
are addressing – ANSYS ensures that our customers
are armed with the tools that will help them to create the most innovative
products on the market.”
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