Flowrate of compressed air required
Flowrate of compressed air required
(OP)
How do I determine what flowrate of compressed air at fixed pressure is required to force a ballast tank full of water submerged at 70m with a volume of 60m^3. The outlet line size is 2inches for the water outlet and the air inlet is 1 inch. Please help if you can. The air will expand as the vessel starts floating up right which makes it even more complicated.





RE: Flowrate of compressed air required
Just tell us your safety precautions and we will try to help.
RE: Flowrate of compressed air required
RE: Flowrate of compressed air required
RE: Flowrate of compressed air required
Perhaps you should consult this with someone who has experience in this kind of manoeuvres, a supplier delivers not only manpower but also experience
Now to your question from a very theoretical point of view . To lift the element you need to equalize the gross weight of the element with the weight of the displaced water by air. Therefore you need to know the weight of the element plus the weight of the water inside of the element. Once you have displaced more weight than the remaining water and the net weight then the buoyancy will start lifting the element.
http://en.wikipedia.org/wiki/Buoyancy
Now comes the second part of your problem. I agree to your conclusion that the compressed air inside of the element will start to expand and displace more water out of the compartments as soon as the upward movement starts, increasing the buoyancy and the accordingly the speed. This could be dangerous, that is why I think you need some professional help.
Submarines perform sometimes emergency surfacing, the huge ships partially jump out of the water. This is a good example of uncontrolled buoyancy.
Only as example:
If you put 60 m3 (Pressurized at the operation conditions 60 m) and the buoy was designed to float with 360 m3 (pressurized at operation conditions 4 m3?) there will not be enough buoyancy.
rgs
RE: Flowrate of compressed air required
RE: Flowrate of compressed air required
Roy