Water Hammer Theory Explained

When a there is a sudden or instantaneous change of flow in a pipe this causes water hammer. Usually this occurs when a valve such as a tap or faucet closes quickly. Water hammer can generate very high transient pressures which could burst a pipe and can generate pipeline vibrations. In this video the process of water hammer is explained and you are shown how to calculate the pressure rise using the Joukowsky equation. The video also proves the Joukowsky equation from first principles. To use the Joukowsky equation you need to know the fluid density, fluid velocity and sonic wave speed in the pipeline. The video shows how to use Hookes law to calculate the wave speed and how this formula is modified to take into account the pipeline wall thickness and young’s modulus.
The video gives an example of how to calculate the surge pressures and wave speed for a 15mm cooper pipe.
Water hammer is part of the larger subject of transient flow or surge analysis. Water hammer is the special case when the flow is stop very rapidly or instantaneously.
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Fluid Mechanics are consultant hydraulic engineers who can analyse and design for surge and water hammer in pipelines.

[@jakobrassi9816]

Thank you for explaining this, this is a very good video. Even 5 years later after being uploaded it is still appreciated by future people, thank you again.

[@Anas-nr6tg]

Exactly what I was looking for, thanks

[@Steven9675]

This is for fluid, condensed fluid. Do you have a session such as this covering steam? I have heard pipes under streets which sounded as though the pounding would break the concrete and would like to see it as related here? Please? Steven

[@manwithtoys9209]

I'm a bit confused. Don't we need to add the calculated delta p to the line pressure to work out the maximum shock pressure before calculating the safety factor (i.e. piping rated pressure / maximum shock pressure)?

[@WladyslawAntonsiewicz9627]

how can we exactly apply this study to calculate the pressure in a compression chamber of a Ram pump... i haven't find a good research of this pump... you explain so nice ... thanks

[@lsouzaleal]

Thank you for explanation. Which equation can be used for gas?

[@omaralnajjar3623]

What doez it mean when you find the SF?

[@Prashant_Bohra]

while finding out rate of mass change, why do we consider the sonic speed(c)?

[@benmoussayoucef4699]

how we can calculate the water hammer if we have 02 pipes in series with diffrent diameter...thank you sir

[@WladyslawAntonsiewicz9627]

I have a question of I have a variable diameter tube.. and connected behind to the tank ... does the wave get to the tank or it stops when the diameter changes ? Thanks

[@AmitKumar-sg8oj]

Sir, could you please explain the effect of different pipe materials on wave velocity

[@PandionStudios]

Thanks Mike. I'm trying to use this to find the air pressure rise on a plunger, being suddenly pushed forwards against the incoming flow. Would you say this would act like the valve being shut instantaneously or would it have a negative time value? So would a negative pressure against the flow (pushing against) create a higher pressure wave front, what sort of multiplier should be used in this instance? I guess it would be added to the flow velocity? One more question, how would we modify this if it isn't in a pipe and it essentially had infinite area as it's convex rather than concave. Setting A to zero in CAP would basically mean Cx0xP = 0? So no pressure rise? Or is this where the flexibility adjustment would come in as the flexibility of the surrounding fluid.

[@kirushanthank.5692]

can you do the pressure propagation in given time and boundary condition

[@miguelmachado4725]

Thank you Mike! Great explanation. Do you know if the modified equation of “c” in flex pipe applies for gases? (i.e. steam).

[@anilsharma-ev2my]

Can. You give equation for Bell siphoning Siphon Inverted siphoning Herons fountain So we got maximum free energy for daily use or we give enough zig zag motion to water hammer so it's boiling with own energy Consider we have 100 meter pipe having zig zag fittings so we got maximum hammering and we can increases the temperature for boiling 100 degrees Celsius ???? So how many rounds will it required ?

[@manjugosain8662]

Can water hammer happen in a 4 storied hospitals fire fighting system of pipes.It has a dedicated water tank with a powerful pump.

[@gummamurthy553]

sir thank you for your great effort in fluid transients. i have doubt that what should be the preset air pressure in the air chamber if static head is 100m

[@SCRSAMI]

is the sonic velocity and acoustic velocity the same thing?

[@DreamEvil121]

just what i needed, thank you

[@rizkyfarizanfiqri7920]

before i am very thank full to professor (mike crowley) has posted about water hammer video which very help me cause i am student of mechanical engineering has thesis to analysis of fluid dynamic phenomena concerning on water hammer (creating hydraulic ram pump with harnessing water hammer as main power). But i still confusing about effect of water hammer after it is rising up the pressure causes water having supersonic velocity after the valve closed, my question actually very simple but i still cannot get the answer. "after water having happened, the water's behave always makes reflection cause the valve closed...and how long the reflection of water inside the pipe ?" Hopefully you can reply my question, that is big favorable to me...

[@Harry-si6ox]

I assume that water supply is elastic pipe (flexible pipe like PPR, plastic pipe etc) this much pressure absorbed in the pipe

[@enzoorciuoli328]

No reflection must have air or will burst system see eng 577

[@rahulkumargarg3224]

I am a research scholar working on water hammer analysis in the pipeline. I want to make a test rig for an experiment showing water hammer phenomena in both for rapid and slow valve closure. my operating pressure is 7 Bar. please advise me how to construct my experimental test rig.

[@srb1855]

Very nicely explained. 👍

[@nickkrasovsky238]

Thanks brother, very fascinating

[@alongkotphoosangad9882]

thank u for more knowledge about fluid

[@marwansallouta2101]

Great explanation, Thank you.

[@omni167]

Thanks for the video. How do we handle the pressure transients in a system?

[@ghafoorhussain5196]

Increase the valve closure time

[@calebsonntangog3995]

sir, can i ask what is that E and e stands for in finding the Sonic velocity at the equation? i cant hear what it stands for. thanks.

[@MikeCrowley]

E is the young's modulus and e is the wall thickness

[@calebsonntangog3995]

thank you sir.

[@calebsonntangog3995]

right now im working on harnessing the force of water hammer. for my project study.

[@mohammedabdin3199]

So helpful. Thank you sir

[@prash2541]

thank you this is amazing

[@arjunsankar3887]

Exceptional

[@khofifahmilleanisa4819]

thank you so much

[@walinoorkhanpaikan2660]

If possible, analyse the water hammer problem analyse in excel.

[@thearcascensionretreatcent3628]

I sped this up to the highest and it’s still sooo slow lol

[@thearcascensionretreatcent3628]

But thank you!!

[@thearcascensionretreatcent3628]

I mean a little arrogant. Come on. It’s water. If youre looking at KZbin for instructions the calculations aren’t that sophisticated. But bravo now I’ll translate! you tell me what a typical hypothesis would

[@AMR_1425]

Thanks Mike...very good info here