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Wait, at 3:25 you said the area spacing between impeller blades is increased radially to convert kinetic energy to pressure energy.And the argument you give is that as per Bernoulli equation increase in area leads to decrease in velocity. But the thing is the impeller blade is supplying energy to the water and therefore Bernoulli equation cannot be applied. Moreover the reference frame is also not inertial but a rotating frame which imparts centrifugal force which we should also take into account. The reasons should be explained taking into considerations these two factors also.
Hi John, Very good presentation as usual I have some doubts 1. Why should the number of channels be less for fluids with high suspended solids and more for fluids with less suspended solids?? 2. Though fully closed impellers have the highest mechanical strength compared to the other two types, why aren't they used for pumping slurries and why open impellers having the lowest mechanical strength are being used for pumping slurries ?
Regarding your second question, slurry pump impellers are often closed. In fact they will almost exclusively be closed because the front shroud has pump out vanes on the outside to prevent frontal recirculation. The only time you will have an open impeller on a slurry pump is if you have stringy fibrous material, froth or the pump size is really small.
The pump impeller draws liquid away from the suction of the pump, which just like sucking on a straw is going to attempt to form some sort of vacuum. This is why net positive suction head to prevent cavitation is very important.
Why is it beneficial to have the increasing channel area toward the outside of the impeller? Also every flow simulation I have seen shows the velocity of the fluid being very high at the outermost part of the channel, which makes sense because that's where the vane linear velocity is at its highest. Wouldn't this expansion in area create unwanted low pressure at the outermost portion of the channel? I understand that this increase in area is sort of inherit to the design of a round object haha, but has anyone done flow tests on an impeller with widening vanes to keep the channels the same area? They must have right?
If a centrifugal pump is fails to deliver water or other expected fluid when first started, what could be the cause? A.pump is not prime B. Impeller flood C. Water seal is pluggged D. Seal ring is improperly located. Sir, can answer this question? Thank you .
Not in a system that’s flowing. The simplest way to understand it is that in fluid flow, there’s three forms of energy. Height or potential, kinetic or velocity, and pressure. Now take two points in the flow. The total energy at the two points have to equal. If you add up the three forms of energy at point A, it has to equal the energy at point B. If any form of energy goes up, another form has to go down an equal amount. The easiest example is if a pipe goes higher by 1 foot, an increase in height or potential, the pressure has to drop by 1 foot. About .4 psi for water. If velocity drops with an increase in area, pressure has to increase by an equal amount. This is what’s happening in the impeller and also the volute. Of course, point B will actually have a little less energy than A because some will be lost to friction.
I recently was running a pump application calculation switching from a closed vane impeller to a semi open vane impeller... the speed needed to pump the same volume decreased by approximately 50rpm with the semi open impeller. Which, will require a drive change... WHY?!
Want to continue learning about engineering with videos like this one? Then visit:
courses.savree.com/
Want to teach/instruct with the 3D models shown in this video? Then visit:
savree.com/en
Thank you sir, when I read this in a textbook it was not very clear to me, great presentation.
Well explained
Thanks. Very helpful video. Salute to your dedication.
Great breakdown ⭐️⭐️⭐️⭐️⭐️
Its good and respeact,
The perfect video.... exists
Thanks bro for that effort
nice presentation
Lovely presentation
Wait, at 3:25 you said the area spacing between impeller blades is increased radially to convert kinetic energy to pressure energy.And the argument you give is that as per Bernoulli equation increase in area leads to decrease in velocity. But the thing is the impeller blade is supplying energy to the water and therefore Bernoulli equation cannot be applied. Moreover the reference frame is also not inertial but a rotating frame which imparts centrifugal force which we should also take into account. The reasons should be explained taking into considerations these two factors also.
good one
Very interesting Video 👍
Very nice video
great video! very HD
Thanks 🙏
what is the function of wear plate?
wouldn't it be better if there was no viscous drag on the outside of the closed impeller?
Hi John,
Very good presentation as usual
I have some doubts
1. Why should the number of channels be less for fluids with high suspended solids and more for fluids with less suspended solids??
2. Though fully closed impellers have the highest mechanical strength compared to the other two types, why aren't they used for pumping slurries and why open impellers having the lowest mechanical strength are being used for pumping slurries ?
Because particles may get stuck
Regarding your second question, slurry pump impellers are often closed. In fact they will almost exclusively be closed because the front shroud has pump out vanes on the outside to prevent frontal recirculation. The only time you will have an open impeller on a slurry pump is if you have stringy fibrous material, froth or the pump size is really small.
Why in eye of impeller there's nagative pressure and why it's suck the Fluid?
The pump impeller draws liquid away from the suction of the pump, which just like sucking on a straw is going to attempt to form some sort of vacuum. This is why net positive suction head to prevent cavitation is very important.
Why is it beneficial to have the increasing channel area toward the outside of the impeller? Also every flow simulation I have seen shows the velocity of the fluid being very high at the outermost part of the channel, which makes sense because that's where the vane linear velocity is at its highest. Wouldn't this expansion in area create unwanted low pressure at the outermost portion of the channel? I understand that this increase in area is sort of inherit to the design of a round object haha, but has anyone done flow tests on an impeller with widening vanes to keep the channels the same area? They must have right?
If a centrifugal pump is fails to deliver water or other expected fluid when first started, what could be the cause?
A.pump is not prime
B. Impeller flood
C. Water seal is pluggged
D. Seal ring is improperly located.
Sir, can answer this question? Thank you .
Hope you passed your test without cheating lol
Good🌸
Can anyone explain how area of impeller is πBD
What about the impeller diameter amd pressure?
Do you have any courses on mixers?
What is the minimum width at the eye & mouth of impeller
Sir i want to pump thick hot sauce using open impeller cetrinfugal pump, is it possible?
how does increasing area increase the pressure? isnt pressure force per area and any unit of increase in pressure should decrease it?
Not in a system that’s flowing.
The simplest way to understand it is that in fluid flow, there’s three forms of energy. Height or potential, kinetic or velocity, and pressure.
Now take two points in the flow. The total energy at the two points have to equal. If you add up the three forms of energy at point A, it has to equal the energy at point B.
If any form of energy goes up, another form has to go down an equal amount. The easiest example is if a pipe goes higher by 1 foot, an increase in height or potential, the pressure has to drop by 1 foot. About .4 psi for water.
If velocity drops with an increase in area, pressure has to increase by an equal amount. This is what’s happening in the impeller and also the volute.
Of course, point B will actually have a little less energy than A because some will be lost to friction.
hi savree basic operating of pump must used euler pump equation and velocity triangles to calculation
I recently was running a pump application calculation switching from a closed vane impeller to a semi open vane impeller... the speed needed to pump the same volume decreased by approximately 50rpm with the semi open impeller. Which, will require a drive change... WHY?!
Because the flow rate increased
4:45 don’t mind me just wanna mark my spot for future explanations lol
it got released at night ;)
impeller
As Area Increase pressure decreases
These are a bitch to machine.