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Courtesy of Lowara
Lowara, a leader in the European residential and commercial pump market,
was established in 1968 in Montecchio Maggiore, Vicenza, Italy. Specializing
in the use of stainless steel technology, Lowara has been part of the
ITT Fluid Technology division since 1977. This division is the world's
largest producer of pumps and complementary products for water and industrial
fluid applications.
Lowara has been using FLUENT since January 2001, and today CFD is an
integral part of their design cycle. The geometry for each new pump or
pump component is analyzed in detail to see how it influences the flow
behavior. As part of this process, FLUENT is used as a virtual test rig.
Whenever a new product has to be studied, the actual operating conditions
are simulated before a prototype is manufactured and tested. This approach
allows Lowara to reduce the number of prototypes and tests, and ultimately
the time-to-market.
The Lowara CO500 pump
While most of Lowara's business relies on mass production, it is
not uncommon to occasionally have specific requests from customers that
need to be satisfied. For example, Lowara was recently asked to modify
one of its products in order to perform at a specific duty point, with
the restriction that the modification not seriously impact the product
cost. Before designing a prototype for a modified pump, FLUENT was used
to investigate the standard pump geometry at different operating conditions:
the duty points corresponding to the best efficiency point and the upper
limit of the working range. As a first step, the geometry of the standard
pump was imported into GAMBIT from a CAD system, and an unstructured tetrahedral
mesh of about 500,000 cells was built. The moving reference frame (MRF)
modeling approach was used to simulate the impeller motion. The numerical
results were very close to experimental values for total head and hydraulic
efficiency. These results, combined with the knowledge that the interaction
between the impeller and diffuser was weak in this pump,assured the engineers
that there was no need to use the morepowerful (yet more time-consuming)
sliding mesh technique. Indeed, the good agreement between the numerical
results and experimental tests (within 2% for the hydraulic efficiency)
suggested that the MRF model should also be used for simulations of the
prototype.
Path lines through the modified pump
During the next phase of the project, several design iterations for the
prototype were studied. Through these simulations, it was possible to
understand how each modification influenced the fluid behavior in the
pump. After assessing a number of solutions, the engineers were able to
determine how best to optimize the geometry in a way that would satisfy
the customer's request.
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