CFD Saves Time in Reverse Engineering a Steam Turbine
by Design World Staff
Thursday, February 26, 2009
NVision’s Contract Service Div. recently
reverse engineered the complete core of a steam turbine for a major OEM
in six weeks compared to the six months budgeted for the project.
“Measuring the critical blade geometry accurately made it possible for
the turbine manufacturer to perform simulations that helped to redesign
the blades and diaphragms to substantially improve the energy
efficiency of the hundreds of existing turbines,” said Steve Kersen,
president, NVision.
The
turbine rotor in this application measured 11 ft by 6 ft and was not
available as a CAD model. NVision technicians scanned all of the
turbine components in three weeks using the NVision HandHeld
Non-contact Scanner and touch probe at the OEM’s site and the MAXOS
scanner.
Computational fluid dynamics (CFD) technology
shows how flow affects the performance of turbine blades and quickly
and inexpensively evaluates alternative geometries by determining their
impact on energy efficiency. To run CFD simulation it is essential to
have a CAD model that accurately depicts the as-built turbine geometry.
Nearly all of the turbines that are prime candidates for design
upgrades were designed without a CAD model so reverse engineering was
an essential first step to improving the turbine blade design.
The
turbine rotor in this application measures 11 ft in length and 6 ft in
diameter. NVision technicians scanned all of the turbine components in
three weeks using the NVision HandHeld Non-contact Scanner and touch
probe at the OEM’s site and the MAXOS scanner in NVision’s Wixom,
Michigan facility.
The
NVision MAXOS scanner can measure complex geometry even if it has a
shiny surface without the need for spraying and it is unaffected by the
limitations of ball radius compensation.
The MAXOS
scanner can measure complex geometry even if it has a shiny surface
without the need for spraying and it is unaffected by the limitations
of ball radius compensation found with traditional coordinate measuring
machines.
Next technicians used NVision software to convert
the point clouds to STL file format. The STL model was converted to a
fully parametric CAD model, which took another three weeks. NVision
engineers edited the resulting CAD models by hand to correct machining
inaccuracies in the as-built parts. The CAD models were then used by
the turbine manufacturer as the basis for the CFD simulations used to
design new blades and diaphragms with improved energy efficiency.
NVision Inc.
www.nvision3d.com
MPF