Good advice Scott, gonna add that to my reference files however I do have a few questions running across my mind when I try to picture this.
1. Easiest one first; Where can you get canned smoke? I can probably find that myself by Googling it but I’m to busy asking questions.
2. What is a “Lip or Venturi shroud”? I can picture a box shroud and I assume the venturi looks like the factory shrouds which transition from a square or rectangle into the round shape surrounding the blade right, but what is a Lip shroud?
3. “no less than 1/2 the diameter of the fan hub away” that would be a pretty large distance for an auto or truck, wouldn’t it? The fan hub diameter on my 6 blade fan is about 3 1/2” and I would have to move the radiator forward a bunch to satisfy that.
4. By a 1” lip I assume you mean that the opening should be flared with a 1” leg on the lip? I take it that this is to help kill the tip losses where the high and low pressure tends to spill out with an open un-shrouded blade?
5. My 6 blade fan profile is 1 3/4”. I’ll round the decimals out here to the closest fraction because we are working with sheet metal. In this case your saying that the back of the box (assuming you are using a box shroud) should be about 9/16” behind the front of the blade leading edge, with the lip extending back another 1” thus ending it at 1 9/16” behind the leading edge of the blade. This only leaves 3/16” of the blade profile behind the lip on this particular blade. This violates the rule ending the lip 2/3 at of the blade profile, which would be at station 1 5/32”. Where would you make your adjustment, by moving the shroud to comply with the back of the box, at the end of the lip or the 1” length of the lip???
And I would think even 20ga would be way heavy, I would think something like 24 or 26ga. would be more in the ballpark for a shroud of this size.
Pain in the ars aren’t I!
Denny Graham
Sandwich, IL
