Air Entrainment Explained

Sections :

00:00 – Introduction
01:02 – Airlock Explanation
02:29 – Airlock Causes
04:34 – Difference Between Airlock and Mild Cavitation
05:29 – Tips to Control Airlock
10:39 - Conclusion

Air Entrainment – A distant cousin of Cavitation
Imagine that you are stuck in a locked room, wanting to go out but there is no escape. How much torture would that be for you? That is the amount of torture that the liquid experiences when air or vapor gets entrapped in a pump system.
Let us discuss about Airlock, how it occurs in the pump system, what are its causes and effects and 4 tips on how to control them, so that you can consider applying them in your pump system rightaway.

References:
Suction Side Problems – Gas Entrainment by James. H. Ingram

Air Release Valve

Vortex Impeller
Inducer
Side Channel Pump

Side Channel Impeller
Choi, Won & Yoo, Il & Park, Mu & Chung, Myung. (2013). Experimental study on the effect of blade angle on regenerative pump performance. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy. 227. 585-592. 10.1177/0957650913487731.

Side Channel Operating Principle - Sero Pumps

Kryptonite

CC0 - Audio :

Vortex Diagram – Pump World 1978 Edititon

Attributions: Licensed under CC

[yhdong]

Thanks very helpful for my project report on pumps

[samersalama]

I'm working on cavitation behavior in sewage centrifugal pumps and I'm facing problem with air bubbles

I have a closed system consisting of:

- 2 cubic meter stainless tank

- Suction line (5m) DN100 with valve

- Pressure line (8m) DN150 and DN100 with valve

- Centrifugal pump with 2 channels impeller, maximum capacity 250 m3/hr (Qopt 170 m3/hr - 14m)

- visual inspection tools installed at the suction side of the pump (light and camera)

Suction and delievery lines are at the same level from the tank side, but inside the tank the delievery line has an elbow and 50 cm pipe towards above
Running the system with fully opened valve at suction side

1- When I run the system at very low capacities like 0, 2 Qopt, I do not have air bubbles, but it appears just when I drop the NPSHa (and the air bubbles are not cavitation, it is just swimming air bubbles)


2- when I increase the flow rate around the Qopt by opening the delievery valve, I can see more air bubbles coming to the pressure side of the pump around infront of the impeller, and this disturbs the visual inspection



3- When I run the system at a higher flow rate at Qopt or higher, I can not even see the impeller from the air bubbles


I have done so many trials and errors, but they did not solve the problem

I put the system under high pressure to check for leakage, but I could not find any leakage
I put the system under low pressure for one day trying to suck the air from water
I let the system running for 4 hours just trying to get rid of the air from the water, then I tried to measure, but it did not help
I changed some connections
I tried even with different pump with vortex 8 blades impeller

I hope you have an advice regarding such problem

Please do not hesitate to contact me for any further required data

[jinakim_energy]

I have a question about air entrainment.
1. What is pump power presented when the flow is reduced by air entrainment issue? Is it reduced as the flowrate reduces?
2. When the air is passing through the pump with liquid, is the air also pressurized and stay in gaseous phase? Or it is not pressurized and dessolved into the liquid?
My question sounds humble a bit. But i really need to get this thing through in my head.