Basic Fluid Dynamics: Calculating Exit Velocity & Mass Flow Rate

AI Thread Summary
To calculate exit velocity and mass flow rate from a vessel under pressure, one can use basic fluid dynamics principles. Ignoring friction, the exit velocity can be estimated by the height the fluid would reach, which is approximately 30 feet for water at one atmosphere, translating to about 45 feet per second. Doubling the pressure increases the exit velocity by the square root of two. For a 1mm hole in a balloon inflated to 1 bar, the air would exit at a speed proportional to the pressure difference. This approach provides a simplified method for estimating fluid dynamics in a pressurized vessel.
bootsnbraces
Messages
13
Reaction score
0
Hi guys and girls,

I hope you can help an electronics engineer out of his place in the mechanical world:rolleyes:

My very basic question is for a vessel holding a liquid at a given pressure and a given opening in the vessel how can i calculate exit velocity and mass flow rate? Like if i blow a balloon up to say 1 bar (good balloon huh:)) and then put a 1mm hole inside it how fast will the air be traveling as it leaves the balloon?


I don't need anything to detailed ( not worried about internal friction losses etc) and for now i can assume the vessel is fed by constant pressure mechanism i.e it won't drop pressure as it empties!

Any help gratefully recieved
 
Physics news on Phys.org
Ignoring friction, the exit velocity should be just enough to squirt a stream back up to the height of the surface of the fluid.

That's about 30 feet for water at one atmosphere. 30 feet at one g is about 45 feet per second. Double the pressure and you multiply the stream velocity by sqrt(2).
 

Thread 'Derivation of Hamilton's Principle: Questions'

I have recently been really interested in the derivation of Hamiltons Principle. On my research I found that with the term ##m \cdot \frac{d}{dt} (\frac{dr}{dt} \cdot \delta r) = 0## (1) one may derivate ##\delta \int (T - V) dt = 0## (2). The derivation itself I understood quiet good, but what I don't understand is where the equation (1) came from, because in my research it was just given and not derived from anywhere. Does anybody know where (1) comes from or why from it the...
View full post »

Similar threads

Does Fluid Dynamics Explain Pressure Gradients in a Frictionless Tube?
Replies
48
Views
6K
Would the velocity of a fluid increase right after exiting a pipe into open air?
Replies
13
Views
4K
Flow of air through an open tube with a balloon
Replies
9
Views
4K
Pressure Gradient for Nitrous Flow
Replies
2
Views
1K
Why Does Hagen-Poiseuille Predict Higher Exit Velocity Than Bernoulli?
Replies
11
Views
3K
What's the pressure long before the fluid exits a pipe?
Replies
13
Views
1K
What causes pressure and is it isotropic in a moving fluid?
Replies
14
Views
3K
Doublet flow in Fluid Dynamics between two spheres or cylinders
Replies
0
Views
1K
How can Bernoulli's principle help explain pressure changes in fluid dynamics?
Replies
6
Views
2K
Applicability of potential flow theory (fluid dynamics)
Replies
3
Views
3K

Hot Threads

Recent Insights

Back
Top