Reverse Venturi

[alw24]

ALL,

Does anyone know of a device that can act as a reverse venturi, so that the pressure increases and the velocity decreases. I know of air ejectors and steam ejectors but I need for this to happen with nothing being introduced into the flow, or at least it being a catalyst and not seeing it at the end flow.
Any help would be much appreciated!

Regards

 

[dickon17]

A venturi uses both priciples. In the leading cone, pressure decreases as velocity increases. In the trailing cone, pressure increases as velocity decreases. Why do you ask the question? What are you seeking? A pump will increase pressure for you.

 

[alw24]

Just looking for an inexpensive way to increase pressure and decrease velocity without using a pump, and not using any other outside means.
So what your saying is the cone leading to the venturi orifice is decreasing pressure and increasing velocity but then when you come out of the orifice the flow begins to have pressure increase and velocity decrease?

 

[dickon17]

Yes, that is exacly right. However, there is an efficiency loss due to turbulence/friction through the venturi. How much pressure increase do you need and why do you need it?

 

[alw24]

So can I get an overall increase in pressure say from 10 PSIG to 30 PSIG or whatever increase if at all possible. I am using this to decrease pricing in my equipment being sold. My prices are directly effected by the amount of ACFM a customer needs and a higher pressure mean less ACFM and this will make the customer happy and buy my product.

Thanks for your help again.

 

[dickon17]

I am sorry, I do not yet understand the requirement sufficiently to make any kind of reasonable suggestion. Exactly what are you trying to achieve?

 

[insideman]

A divergent-convergent duct is used with airplane radiators to slow the and increase the pressure at the radiator. This actually produces a bit of thrust!
But pressure increases of the magnitude you are seeking are not in the cards. Do the analysis!

 

[djack77494]

alw,
I'm not sure what you are asking. According to Bernoulli, Pressure WILL increase as velocity decreases. A simple pipe reducer (installed as an expander) achieves this effect. Of course, this simplistic approach is not very efficient, and you will have hydraulic losses. In theory, with an efficient nozzle, the final pressure achievable would be the total fluid pressure = static pressure + dynamic pressure at the nozzle's outlet.
Doug