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Old Feb 08, 2013, 12:49 AM
TheyreComingToTakeMeAway!
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just a question, on the rear portion in the first picture, are the vanes going the same direction as the airflow so they have no net effect and therefore all the "straightening" is done in the inlet side?

very cool design too, i like the idea that all the moving parts are totally contained
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Old Feb 08, 2013, 05:01 AM
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Old Feb 08, 2013, 05:04 AM
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derk,

I am not completely sure, how the stator blades have to be shaped. I compared some designs. This is a first attempt, the pitches of the stators are subject for optimization. Have a look at the cross section. The stator is supposed to catch the rotating stream and bend it back straight. The upper surface of the trailing edge is pretty much in line with direction of flight. Maybe the pitch needs to be a little higher. Many designs have a more curved airfoil for the stators, I will look into this but didn't want to introduce too many parameters I don't know the effect of Input is always welcome...

Chris
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Old Feb 08, 2013, 07:55 PM
TheyreComingToTakeMeAway!
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someone else chime in if i'm way off base with this idea; i would think that the airfoil on the front stators should be reversed to try and get the incoming air to rotate into the direction of the fan, so the blades are going "into the wind". this could add more load to the motor so it might be better off keeping that section straight and using the rear ones like ordinary fans do, it would have less direct effect to your motor loads and still straighten your efflux.

again, i could be wrong, your guess is probably better than mine as i have not built that many edf planes
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Old Feb 08, 2013, 08:42 PM
Life begins at transition
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In a perfect world (hence the design of the SM110-52), the inlet guide vanes apply the same amount of swirl as the rotor, but in different directions. Which would mean no stators (outlet guide vanes) would be needed.

For multi-stage compressors, the OGVs set the inlet conditions for the next stage, which is why they look different to what we're used to.

IGVs can be used to either increase or decrease the AoA of the rotor, to make the motor's life easier or harder. If the rotor is pushing into the wind, it'll be harder (but should get more thrust too); if it's got a bit of a helping hand from the IGVs it'll reduce the load (and thrust).

Was there a particular aero reason for both IGVs and OGVs, or was it more structural?
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Old Feb 09, 2013, 02:29 AM
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The reason for two stators is that I want to have the motor in front to get the cg rigght and to have a short tail pipe to plug on. I am also making a standard configuration (outtake stator) for testing and future projects with the type of fan I already produced (with spinner). That one would reach way into the wing of the squall, so the wings wouldn't be connected so well, when I make the tail pipe removable. Also the fin then has to be attached to the removable part. It's doable and maybe I go that way if the efficiency looks much better with one stator. I have build pusher motor setups all the time now, usually with thin straight vanes to hold the motor. This is the first time I can make more fancy structures.

Please Odysis, in short, is the principal orientation of both stators correct? I do want to add load to the motor. Maybe I shouldn't? As I see it, the intake stator turns the stream against the movement of the fan. The outtake stator catches the stream that now rotates in the direction of the fan and straightes it. How else would the foils need to be oriented? Maybe more positive camber is required, then it looks clearer. Maybe the pitches are not perfect, especially the outtake one could be more straight or more cambered. But for a first try, is it way off?

On my first run I wanted to vary the blade counts, on the second one the pitches and maybe camber.

Looking at the gws edf stator, it has much less pitch but the same orientation. I don't think that one is perfect. The wemotec microfan has cambered stator blades, where the trailing edge is straight and the leading edge is pointing against the rotation. Like I have done just more camber. Nitro is doint that too.

Thanks for help...

Chris
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Old Feb 09, 2013, 02:36 AM
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The OGVs are relatively easy - they should point straight out at the TE (actually, about 3 or 4 degrees past straight, as the Kutta condition isn't absolute...)
IGVs can be anything from non-existant to both ways if coupled with OGVs. IGV only is very difficult to do, hence they're not seen often.

With the motor out the front, both sets make perfect sense. Perhaps have three forward sections made up, say 5deg into the rotor, straight and 5 deg away from the rotor. Then you can use that to fine tune the load on the motor without printing a new rotor?
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Old Feb 09, 2013, 03:40 AM
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Thanks for the input, I might make a straight intake version, with the current orientation of the airfoil, or should I also use a symmetric airoil then?

BTW, guess how much a set of 24 parts for 6 fans costs in frosted ultra detail

Chris
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Old Feb 09, 2013, 04:24 AM
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A symmetrical for zero camber (straight). Not sure how you could use the current airfoil with a straight? The LE of the IGV needs to point straight forward, it's just the angle of the TE that changes. Likewise, the TE of the OGV points straight backward.

I'm guessing less than the postage! Once SW brought that in, I couldn't justify printing a couple of fans to try things out
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Old Feb 09, 2013, 04:30 AM
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It's 10Euro+ 8Euro shipping for one unit with six fan sets. I think that is really cheap to try things out. You just have to think ahead and print a couple of sets at a time.

Chris
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Old Feb 09, 2013, 06:17 AM
Life begins at transition
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8e's not bad at all; it's $20 to get down here!

The results guys are getting with FUD look great though, can't wait to see how yours turn out (and push the plane around!)
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Old Feb 09, 2013, 04:10 PM
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BTW, I see a simple reason why to implement OGVs: Even if the IGVs do a perfect job on the swirl, there needs to be something to hold the cone behind the fan. It could be attached to the fan of course, but not at this length. A non rotating cone is better anyway, cause it doesn't cause additional swirl. The cone optimizes the transition from FSA at the fan to 0.85*FSA at the outlet...

Chris

P.S.: here is the latest set. At the top right you see the standard configuration without IGVs and motor behind the fan. I also added a second motor frame to each fan assembly and working out a different coil shape. Not finished yet. Will order on monday...
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Old Feb 09, 2013, 10:51 PM
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Let the parts sit in soapy water (I use dawn dish soap) for about half an hour or so. Then use as much water pressure as you are comfortable with using to clean the parts off. It gets rid of the excess residue.
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Old Feb 11, 2013, 04:13 AM
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One last question before I order the first set. Does anybody have experience in making fits with the frosted ultra detail material? I need to choose the correct size for the hub ID so the motor frame slides in and sits tight. At the moment, the diameters are identical, but I fear that it won't fit this way. Should I make the hub ID something like 50um wider?

Thanks

Chris
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Old Feb 13, 2013, 05:14 PM
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Exact, or smaller. Remember, you can lose material, but you can't add it. The printings aren't exactly identical every time. I have had rotors that slide right off while others fit nice and snug.
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