CFD software’s success with flush
Computational fluid dynamics (CFD) software from Flomerics has slashed the design time of an innovative flush valve
US company Johnson Design’s Denali Flushometer flush valve delivers a fixed volume of water independent of the position of the restriction on the rolling diaphragm which is randomly installed at various positions during the valve assembly.
Engineering manager Dustin Borg used Flomerics’ EFD.Lab to evaluate the performance of the valve as the restriction was rotated 360º, in order to ensure that it delivered the right amount of water in each position.
“It reduced the time required to optimise the design by enabling us to evaluate design concepts in software without having to build a prototype,” Borg said.
Flush valves take advantage of pressure differentials between the inlet and control chambers. The pilot valve, when engaged by the handle, vents the control chamber – lowering its pressure and allowing the rolling diaphragm to open, which begins the flush cycle. Rolling diaphragms expose only a small area of unsupported diaphragm to pressure differentials, resulting in much lower forces.
“But it’s usually not possible to determine in advance where the restriction on the rolling diaphragm will end after the valve is assembled,” Borg said. “One valve of the same model may deliver 1.5 gallons while another will deliver 1.7 gallons. We decided to overcome this problem in the Denali Flushometer by evening out the pressure that the valve is exposed to around its entire circumference.”
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