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Venturi Design

09/13/2010 6:20 AM

What is the right taper upstream and downstream of a venturi tube in order to get the maximum suction pressure? Can the two sides be identical?

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#1

Re: Venturi Design

09/13/2010 8:37 AM

Clarification request: is this thread about a Venturi tube, which is a flow measuring device, or is it about an ejector, which is a fluidic vacuum-generating device?

The answer is: "that which introduces the fluid into the throat of the Venturi at the highest achievable Mach Number."

→ Perry, "The Chemical Engineer's Handbook", any edition.

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#6
In reply to #1

Re: Venturi Design

09/14/2010 8:34 AM

I am looking for an eductor design. ..... You have answered what i am looking for theoretically i.e highest possible Mach no. of the inlet fluid is what we should design for. ..... Are there any thumb rules in the taper design. ..... My application is for a domestic appliance where the flow rate is not very high and hence i need to create the maximum suction at the throat.

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#2

Re: Venturi Design

09/14/2010 1:12 AM

Like PWS asked - what is the use to be?

Correctly designed inlet/outlet cones never have the same angle that I have seen.

Perrys and Marks (as I remember) plus a Shell Oil design guide are definitive guides for venturi design.

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#5
In reply to #2

Re: Venturi Design

09/14/2010 7:55 AM

Hi Russ,

I've had a look on Google for both the Shell Oil guide and "Marks" publication, but haven't turned anything up as yet. Do you have any more details for these references ?

Thanks

DesEng

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#8
In reply to #5

Re: Venturi Design

09/14/2010 10:52 AM

Marks' Standard Handbook for Mechanical Engineers

I also searched for the Shell book that I mentioned and found nothing. I had a copy years back but it is long lost. I the topic was flow measurement of all types with one section on venturis for flow measurement.

As you are interested in an ejector stack the Marks would be more useful. They are quite useful if you can afford the power required.

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#3

Re: Venturi Design

09/14/2010 2:55 AM

if it is for measuring the pressure difference then refer to the HVAC hand book

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#4
In reply to #3

Re: Venturi Design

09/14/2010 3:27 AM

I am looking for an eductor design. ..... I guess PWS has answered what i am looking for theoretically i.e highest possible Mach no. of the inlet fluid is what we should design for. ..... Are there any thumb rules in the taper design. ..... My application is for a domestic appliance where the flow rate is not very high and hence i need to create the maximum suction at the throat.

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#7

Re: Venturi Design

09/14/2010 9:10 AM

I apologize up front since I haven't college or much of any formal training. But the fellow is asking for maximum performance - all the time! However no one has mentioned that in order to get max with a 'set' configuration - the pressures need to be steady on each side of the venturi. Because different pressures on either side will mean different requirements for maximum performance. I suppose you then need to consider tuning ports to balance things out. Good luck. Carlos

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#9
In reply to #7

Re: Venturi Design

09/14/2010 11:40 AM

Hello,

You can get the right design by using "CFD" based tools.

Regards

Madhav Chowdhary

SWEE Technologies

Pune city, India

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#10

Re: Venturi Design

09/14/2010 12:39 PM

Hi Admeraj,

Keeenan et al originally produced the theory for ejector/eductor design that has been subsequently validated using CFD and experimental apparatus. A copy of their 1950 paper (journal of applied mechanics ) can be found here

This paper should provide you with all the info you need to design your own ejector.

Good luck

DesEng

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#12
In reply to #10

Re: Venturi Design

09/15/2010 2:03 AM

Thanks. This was useful.

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#13
In reply to #12

Re: Venturi Design

09/15/2010 9:19 AM

Glad to of help.

and glad to notch up my first GA

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#11

Re: Venturi Design

09/14/2010 12:59 PM

Aitkens Mfg in houston Texas makes them

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Users who posted comments:

admeraj (3); Anonymous Poster (2); Carlos J. Valdez (1); design-engineer (3); madhavchowdhary (1); PWSlack (1); russ123 (2)

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