Linear Ram Pump

[HuntingRoss]

I'd like to introduce you to my interpretation of the linear ram pump.

For your delight and delectation -

[VIDEO]https://www.youtube.com/watch?v=pcwbYkBphg0&list=PLbPpmQ1GdtLP7xj_IbXs-wZc_vkeMaDtp&index=1[/VIDEO]

[HuntingRoss]

[VIDEO]https://www.youtube.com/watch?v=pcwbYkBphg0[/VIDEO]

[mikrovolt]

[VIDEO]https://www.youtube.com/watch?v=pcwbYkBphg0[/VIDEO]

Thanks for the topic. I really like your magnetic valve and the future
advancement of ram pump technology.

Not an easy subject takes specialized hydraulics
I think maybe finding a smart plumber to explain a related art found in
industrial plumbing about the phenomena of water hammer.

" A sudden change in velocity "

https://www.youtube.com/watch?v=Yj88lQruKE4

[HuntingRoss]

The Hammer Effect

Nice link, microvolt.

I never had an equation for calculating the hammer pressure, AND it's a really simple one. Thanks.

[mikrovolt]

One source attributes the discovery to

Joukowsky.JPG

Is it fair to say that water reacts to compression because of bubbles ?

How do you find the excess pressure in a ram pump ?

[HuntingRoss]

How do you find the excess pressure in a ram pump ?

Hi mikrovolt

From the link you provided previously, the slide 'Uncontrolled Hydraulic Shock' at 3:41 states -

"the potential magnitude of these pressure or acoustic waves for the same intensity, energy pressure in water is 60 times greater than air"

The slide at 4:46 states -
"Rule of thumb formula for pressure increase P = 60 x (V x S)/T
P = Increase in pressure (pressure spike)
V = Fluid velocity in the system in 'feet per second'
S = Specific gravity
T = Time for valve to close in seconds
60 = Constant

The formula estimates the pressure spike which is added to the steady state flow pressure, slide at 7:16.

Is it fair to say that water reacts to compression because of bubbles ?

My depth of knowledge on the subject is not so vast that I'm likely to deliver great insight on the subject. But I would hazard a guess that a degree of compression is possible in water (considered incompressible) with the presence of dissolved gas, compared to a single phase liquid absent dissolved gas. The recoil demonstrated in the footage from your first link certainly seemed to create cavitation upon sudden closure of the valve (indicating the presence of dissolved gas)...which is to be expected when cavitation can be easily demonstrated behind the blade of a fast moving prop.

Again. From that video, I would presume that the compression of a liquid however slight would serve to lessen the impact due to the slight slowing of the fluid compared to single phase fluids which would suggest a sudden stop.

But. As hammer is caused by a rapid slowing rather than necessarily sudden stop then notional compression may have little real effect.

It certainly is a much more interesting subject than would first appear obvious. And given Blacoh's involvement tends to be due to poor initial system design it clearly remains a misunderstood issue for engineers that should know better.