Consistent Air Velocity
Consistent Air Velocity
(OP)
HVAC Engineers,
Need your advice on the design of a makeshift supply air diffuser that would provide consistent air velocity across the entire opening.
Due to the constraints of this project, I need to come up with a way to insure consistent air velocity across a diffuser that will be at a considerable length (+8'). This problem is exacerbated with the supply air having to come in at one end of this diffuser and it cannot be centered in the length. I need to maintain 150 FPM across the entire length of this diffuser.
I am having a hard time coming up with the correct formula for this to ensure the air opening area is properly sized so that the air does not decrease or increase in velocity at one end of the diffuser over the other. I need to make sure the diffuser is properly pressurized over its entirety to maintain the velocity.
This would be a rectangular diffuser as far as the plenum goes, but I am open to suggestions on whether rounded would serve me better.
Thank you.
Need your advice on the design of a makeshift supply air diffuser that would provide consistent air velocity across the entire opening.
Due to the constraints of this project, I need to come up with a way to insure consistent air velocity across a diffuser that will be at a considerable length (+8'). This problem is exacerbated with the supply air having to come in at one end of this diffuser and it cannot be centered in the length. I need to maintain 150 FPM across the entire length of this diffuser.
I am having a hard time coming up with the correct formula for this to ensure the air opening area is properly sized so that the air does not decrease or increase in velocity at one end of the diffuser over the other. I need to make sure the diffuser is properly pressurized over its entirety to maintain the velocity.
This would be a rectangular diffuser as far as the plenum goes, but I am open to suggestions on whether rounded would serve me better.
Thank you.





RE: Consistent Air Velocity
RE: Consistent Air Velocity
RE: Consistent Air Velocity
RE: Consistent Air Velocity
RE: Consistent Air Velocity
RE: Consistent Air Velocity
B.E.
You are judged not by what you know, but by what you can do.
RE: Consistent Air Velocity
The diagonal line would be the perforated plate and the arrows designate the airflow through the diffuser.
RE: Consistent Air Velocity
You are on the right track, give your self a little more room at the right hand end. Maybe an inch or so behind the screen.
then make absolutely sure that the free area of the perforated plate, is less, than the surface area of the incoming duct.
You want the air to pile up in there and re-distribute itself through the perforations.
B.E.
You are judged not by what you know, but by what you can do.
RE: Consistent Air Velocity
Are you saying to angle the perforated plate towards the diffuser outlet on the right hand side to within 11-10 inches of the outlet?
Also, would Solidworks fluid simulation be of any help here? I have access to it but not sure if it would be of any help.. has anyone had experience with it for a similar situation?
RE: Consistent Air Velocity
RE: Consistent Air Velocity
Linear slots:
http://www.acutherm.com/products/linear-vav-diffus...
Square diffusers:
http://www.titus-hvac.com/file/8313/vavdiffusers.p...
RE: Consistent Air Velocity
RE: Consistent Air Velocity
It might seem like an insignificant requirement but I need to stick with it.
I'll try to run a fluid simulation on it and see how it goes.
Thanks for the input.
RE: Consistent Air Velocity