What type of fan generally yiels the fastest output velocity?

[infamous_Q]

Hey everyone i was just wondering, for future reference, which type of fan generally yields the greatest output velocity/volumetric flowrate and a relatively low pressure drop (ie like +/- 10kpa sort of thing), assuming axial speed is the same for each of the general types of fans. This would be for an application in a tube approximately 2.5 - 4 cm in radius. If i need to be more specific let me know, of if there's a specific answer out there that'd be great too.
I know this is very vague, but thanks for your help guys!

 

[FredGarvin]

The output of any fan is going to be greatly dependent on the system it is attached to. You can do direct comparisons if they discharge to free air, but after that, their respective curves could vary greatly. So it looks like the answer is it depends.

What's the application?

 

[russ_watters]

Tough to look for high velocity and low pressure drop, since high velocity tends to mean high pressure drop (at the very least, it is a high velocity pressure, of course). In general, the most efficient type of fan is a centrifugal plug fan, but it is, of course, going to depend on your application whether that is really appropriate.

http://www.cincinnatifan.com/PlugFan.html

 

[infamous_Q]

alright, the application (in the most basic sense) is air flowing from one large tube (about 10cm in radius) to a small tube (2.5-5cm in radius) and then the air flows through the fan (seperately driven by a motor). Basically any type of fan can be applied to this (space isn't too much of an issue really, configuration comes later). I also have Solidworks and FloWorks at my disposal, so if there are basic designs out there that i could follow, then i can probably test these myself. The problem for me thus far is finding designs. And the faster the better.
Thanks again guys.

 

[russ_watters]

How much flow are you looking for and for what purpose?

 

[Gigabyte111]

just out of curiosity,

what are you trying to acomplish with building this device?

also the transition from the larger tube to the smaller tube would eithere have to be gradual, and semi-smooth, or it would have to be very very smooth, and then could be more abrupt

otherwise the air flow would be dissruped, thus reducing the overall efectiveness of the fan.

also, is the air being forced into the larger tube to exit throught the smaller tube, or is it being pushed into the smaller tube to exit from the larger tube?

if you are going for the maximum efficency, you should also make sure that your design is more efficent then your fan.

 

[infamous_Q]

- flow rates in excess of 1m^3/s are what I am looking for.
- large tube to smaller tube

 

[Gigabyte111]

- flow rates in excess of 1m^3/s are what I am looking for.

but why do you need such high rates? what would they be be used for.

 

[infamous_Q]

is it really that important or is it just that you're curious?

 

[FredGarvin]

So you're doing a hovercraft project? What is your reasoning behind wanting the highest velocity?

 

[Gigabyte111]

is it really that important or is it just that you're curious?

im just curious, because some of your reasearch might help me in a model Ufo i am building, that is and has been grounded until i get more money to by 4 extra ducted fans to supply the rest of the needed lift

 

[infamous_Q]

well, in regard to my research...there really isn't any, just some flakey ideas, this is the extent of it. and yes it's regarding some sort of hover craft, the idea for this is lift and propulsion, which is why the high flow rate is needed. Any ideas now? lol. thanks guys.