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foo9008
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The jet is assumed to be a free jet (unconfined by a tube) so the (gauge) pressures at the very inlet and the very outlet are assumed to be zero.foo9008 said:
Unconfined tube? What is that? i could see the pipe thereChestermiller said:
I don't think they meant to show it as a pipe. I think they meant to show it as an unconfined jet. This is my interpretation anyway.foo9008 said:
unconfined jet ? what is that ? what's the difference between unconfined jet and pipe?Chestermiller said:
When you shoot water out of a hose, that's an unconfined jet.foo9008 said:
why in unconfined tube (jet) the pressure at both end are assumed to be 0 ?Chestermiller said:
form your explanation above , do you mean the jet coming from a hose which enter the stationary blade?Chestermiller said:
You have the right idea. What I'm saying is that it will increase at the blade surface, but, at the free surface, the jet is still in contact with the air, so the pressure at the free surface will still be zero. In the region where the jet is in contact with the blade (and changing direction), the fluid pressure will vary across the diameter of the jet, from a high value at the blade surface to zero at its free surface.foo9008 said:
do you mean both my idea aforementioned correct ?Chestermiller said:
foo9008 said:
I don't know how to say it any better. In the region where the liquid is changing direction when in contact with the blade, the pressure within the liquid varies across the cross section of the jet from a high value at the blade surface (as you said, pressure will increase ") to a value of zero at the free surface of the jet, all within the same cross section of the jet.
do yuou mean the water pressure increases from the inlet to the bent part of the pipe , then it decreases to 0 at the outlet of the pipe ? since at the outlet of the pipe , the pressure acting is no longer water pressure , but atmospheric pressure?Chestermiller said:
No, no, no. I said it increases across the diameter of the jet. A pressure gradient across the diameter of the jet is required to change the direction of all parcels of fluid comprising the jet (both near the wall and near the free surface), because each parcel is being accelerated (i.e.,changing direction).foo9008 said:
You need to understand 2 things:
I thought when the water is flowing and friction is ignored , the velocity of water across the straight pipe would be constant ? thus , the pressure gradient would be constant ? ( consequence of beroulli's principle ) ?Chestermiller said:
That's only if the streamlines are straight. If the streamlines are curved, the pressure varies between streamlines. How else could the parcels of fluid be accelerated normal to a curved path (centripetal acceleration)? After the streamlines straighten out again, the pressure becomes uniform across the cross section again.foo9008 said:
Chestermiller said:
Yes.foo9008 said:
We can, but it's easier to use gauge pressure.
Pressure in bent pipe refers to the force per unit area that is exerted on the walls of a pipe as a result of fluid flowing through it. This pressure is caused by the resistance of the fluid to flow and can vary depending on the fluid's velocity, density, and the geometry of the pipe.
In a bent pipe, pressure changes due to the change in direction of the fluid flow. As the fluid moves through the curve, it experiences a centrifugal force that causes it to push against the inner walls of the pipe, resulting in an increase in pressure on the outer side of the curve and a decrease on the inner side.
The main factors that affect pressure in a bent pipe are the fluid's velocity, density, and the curvature of the pipe. Higher fluid velocities and densities, as well as tighter curves, will result in higher pressure in the bent pipe.
Pressure in a bent pipe can be measured using a pressure gauge or manometer. These instruments use the principle of fluid pressure to determine the force per unit area exerted by the fluid on the pipe's walls. The units of measurement for pressure are typically pounds per square inch (psi) or pascals (Pa).
Understanding pressure in bent pipe is important in various industries, such as plumbing, hydraulics, and fluid dynamics. It is also crucial in designing and maintaining pipelines, as well as in optimizing the flow of fluids through curved pipes. Additionally, knowledge of pressure in bent pipe is essential in preventing and troubleshooting issues such as leaks and blockages in pipelines.
