Appliance Design - June 2008 - (Page 38)

FaNS & BlowErS Optimizing Flow In these close-ups underneath a wolf cooktop, vector arrows show direction of air movement and colors show velocity; blue is slower, red is faster. CFD simulations speed the product design process. by jeff waters Jeff Waters is account executive at Blue Ridge Numerics, Charlottesville, Va. 38 applianceDESIGN June 2008 ppliances have issues. Flow and thermal issues to be exact. The movement of air, water, and other fluids at proper temperatures is vital to every appliance. Adding the ever-increasing demand for efficiency and environmental controls yields complex interactions that can determine the success or failure of a new or updated product. Efforts to optimize thermal and flow characteristics for appliances can be aided by utilizing CFD early in the product development cycle. Using automated software to visualize flow and heat issues early in the design process enables greater design experimentation, reduces costs incurred with physical testing, and speeds the development cycle. One appliance company that has benefited from upfront CFD is Wolf Appliance, Madison, Wis., which uses CFdesign software from Blue Ridge Numerics, Charlottesville, Va. Wolf has integrated the software into the development process for all of its products, including wall ovens, warming drawers, electric cooktops, induction cooktops, and dishwashers. Appliance design challenges at Wolf are far from simple. Take, for example, the company’s signature oven. For proper selfcleaning, the interior surface of an oven door needs to reach at least 800 DegF for two hours, while about 2 in. away, the stainless a steel surface must stay below 150 DegF to ensure consumer safety. A typical Wolf electric oven has five heating elements and two convection fans for even cooking; if there is a design flaw in the elements or the fans, the result could be uneven cooking and inefficient performance. Ben Hanson, design engineer for advanced product development at Wolf Appliance, has found that using CFdesign early in the development process can flag design flaws that may not have been seen until the prototyping stage. Discovering a flaw at that point previously had resulted in the project taking a major step backwards or concessions being made to work around the issue. Hanson cites Wolf ’s double-wall oven as an example of the value of upfront CFD. The oven has two cooling fans, and during initial design it appeared as if they would function properly. But when the CFdesign analysis was run, Wolf ’s engineers found that the air ducting was not segregated enough. Hot air was re-looping between the two fans, causing the cooling system to run hotter than desired. The design was brought back into SolidWorks CAD software, where the ducting was changed and tested again in CFdesign until the problem was solved. Correcting the issue enabled Wolf to pass UL and CSA testing and increase the oven’s www.applianceDESIGN.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - June 2008

Appliance Design - June 2008 Contents Editorial Shipments/Forecasts News Watch 21st Annual Excellence in Design Winning Designs Combine State-of-the-art Technology with . . . Meet the Judges Design Marts Fans & Blowers Mother Nature Has Her Own Ideas About Designing for Fluid Flow . . . Using CFD Simulation Software Early in the Product Development . . . Electronics Digital Signal Controllers Enable Digital Motor Control . . . Classifieds Meetings Advertiser’s Index Association Report: AHRI

Appliance Design - June 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.