Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


Airflow through venturi

Airflow through venturi

Airflow through venturi

We wish to modify a venturi/eductor to make sure that we are getting the best vacuum possible when a compressed air motive is applied to it. I was hoping to find someone or company that is knowledgeable in this type of equations?

RE: Airflow through venturi

Apply a vacuum gage and a big compressor, and measure what you get.
If it's not enough, get a bigger compressor.

Or, better, get a water-driven eductor and use water as your motive fluid; it's much less noisy than air.
This one should work fairly well on city water, for not a lot of money:

A search on eductors, venturi pumps, and related phrases will bring up half a dozen well known companies that produce this stuff to fairly high precision, with predictable performance. The market is not large, and you need to cut away a lot of material from a billet to make the parts, so they can be fairly expensive.

Mike Halloran
Pembroke Pines, FL, USA

RE: Airflow through venturi

Thanks for your email Mike. What I need is someone that can actually calculate the flows based on a design print that I would forward over. This was an actual eductor we had made years ago and the company is no longer around. What we where looking at doing is to tweak the drawing to be able to power with 400 cfm or air and 750 cfm of air, at present the design was made to use 500 cfm of air(motive) and to know what dimensions(ports sizes) and lengths that would need to be changed. It's basically someone that knows this science and how to design them. I have attached a photo of the current one showing it together with the nozzle. We tried increasing the hole size in the nozzle to accommodate more air but the other dimensions would need adjustment also to fine tune this whole unit that will give us the best flows and deepest vacuum possible. Does anyone know of a company or person that can assist with this type of design work?

RE: Airflow through venturi

That thread mentions S-K and Fox Valve.
A quick search also brings up:
Jacoby Tarbox
Alfa Laval

Surely one of them, or a friend or emeritus thereof, can be persuaded to help.
Just pick up the phone, and social-engineer your way to the real engineers.

ISTR that I found a set of equations in one of those thick ME Handbooks, which are all in storage right now, and tried to work through them. Eventually I just scaled an illustration in a catalog, and tried to sort of duplicate that.
I made one, a long time ago, from standard tubing fittings, that worked well enough to atomize some solvent and spray it on something I was trying to degrease.
I've made another from pipe fittings with a laser-cut core, that was intended to suck condensed water out of big exhaust pipes without being burned up by the exhaust gas. It worked well enough to do that, and to help drain a flooded floor.
I.e., it's fairly easy to make an eductor that works well enough to amaze people who have never seen one work, but predicting and adjusting and optimizing its performance takes some experience that I don't have.

Good luck.

Mike Halloran
Pembroke Pines, FL, USA

RE: Airflow through venturi

Ah HA... air ejector system.

Suggest searching NACA tech report server http://ntrs.nasa.gov/search.jsp using terms 'air ejector'

NOTE: the term 'air inductor' will not work... the term 'inductor' is interpreted as an electrical component/function.

The jet I work on has a 'air mover system' [which is actually an air ejector] which is placed downstream of a heat exchanger [HE]. ON THE GROUND [no airspeed], pressurized air is pumped thru the many ejector nozzles inducing air flow from the inlet, thru the HE, the out the exhaust port [airflow is essentially 'pulled' thru the system]. When airborne, this 'air mover system' is turned-off and dynamic air-flow is brought-in thru the NACA inlet, up-stream of the HE... which then pushes air thru the same HE duct to the [same] exhaust port [around/thru the non-operating air-mover nozzles].

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion"]
o Learn the rules like a pro, so you can b

RE: Airflow through venturi

seriously, have you tried a google search for "venturi equations" ?

there seems to be lots of stuff ... some have to be able to help you ...

another day in paradise, or is paradise one day closer ?

RE: Airflow through venturi

Looking at your other posts you seem to be involved in sand conveying systems.
There is a body of knowledge in this trade for air operated vacuum venturis, as a component in air conveying systems.
I have used these devices in the aircraft trade for pickup of spent plastic paint stripping media from stripping booth floors.
I am posting a link to one manufacturer, this may lead you to others. I get the idea that you really don't want engineering help, that you just want a company to do the job for you.

You are judged not by what you know, but by what you can do.

RE: Airflow through venturi

I can try to help. Could you supply some more info please? Compressed air pressure, description and flow rate of fluid you want to entrain

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close