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I'm no expert on flow dynamics and I'm new to EDF, but from what I've read so far on this forum, everything that smooths airflow through the duct is very important.
Without the spinner, air will have to change direction very suddenly as it hits the hub face vs. flowing smoothly around the spinner into the fan blades. I've learned that small things like this can take a huge toll on fan efficiency. Just my .02 worth, by all means get a second opinion.... Jim |
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My experience is that it depends on the model, and in particular on the inlet ducting. If the airflow has already a slight turbulence at and around the spinner location, it won't matter much whether it's on or off. It seems the air will create its own spinner... I was quite astonished on some of my earlier models to notice the absence of any detectable effect when you took the spinner off. If the ducting is really straight & smooth I have noticed though some significant changes in sound when you take the spinner off, ie increased turbulence.
If you do have the time and patience, I would suggest though to painstakingly balance the prop and spinner, it's worth the effort, http://aeneas.ps.uci.edu/edf/fan/balancer_1.jpg One thing that seems to have very little effect (around less than 1/2 oz of st thrust in a HW-609) is the streamlined carbon fiber cone aft of the motor, http://aeneas.ps.uci.edu/edf/mig17/p3010006.jpg |
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Last edited by Herb; Sep 14, 2001 at 01:34 PM.
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