MixSim: Retreat Curve impeller: How do I tell the impeller diameter?
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I've been given the task to simulate a retreat curve impeller with a given diameter. In MixSim, there is no option to enter the impeller Diameter. What can I do? Try the following: - activate the check box (toggle option) "FixZoneDimensions?". This will advise MixSim to display the (now fixed) MRF zone dimensions in the preview graphics. - Modify the definition of the "RotZoneDia" parameter: Remove the " + [BladeThickness]" from the definition, so that the whole definition reads simply "[Diameter]". - By this, MixSim will calculate, display, and visualize the impeller diameter as the diameter of the MRF zone boundary (parameter "RotZoneDia"). - Now play with the other parameters. You will find that... + The "Blade Length" is the length of the blade along its *curved* center line, from the hub surface to the blade tip. + If you set the blade curve radius to a very high value (100 meters or 1000 meters), the blade becomes (almost) straight, and the impeller diameter equals almost exactly the expression "2 * blade_length + hub_diameter". A small deviation in this equation results from MixSim accounting for the blade *thickness* also. This becomes obvious when you reduce the "Blade Curve Radius" again. + The automatic calculation of the impeller Diameter (which we display and visualize through the "RotZoneDia" parameter) does currently NOT take into account the.. o Retreat Angle and... o Blade Angle ...parameters. - Please REMEMBER to add " + [BladeThickness]" to the equation defining the "RotZoneDia" parameter. Also, if you are using the "Retreat Angle" or the "Blade Angle" parameter, please consider double-checking the calculated MRF zone dimensions by temporarily fixing and viewing them in the preview graphics. - Finally, consider releasing the "FixZoneDimensions?" check box (toggle button) again, so that MixSim can grow the MRF zone when there is sufficient space available for that. |
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