Ventilation Pipe
Ventilation Pipe
(OP)
Hi folks,
I am designing a ventilation pipe for one underground tunnel. The pipe is a 500 mm dia 105 m high, made of seamless carbon steel. The volume it requires to cater is 47 cubic m/sec (cumec) which gives an air velocity of 239 m/sec.
I need your advise on aerodynamic behaviour of pipe, especially on vibrations considering Mach number is very close to 1.
Thanks in advance,
flame
I am designing a ventilation pipe for one underground tunnel. The pipe is a 500 mm dia 105 m high, made of seamless carbon steel. The volume it requires to cater is 47 cubic m/sec (cumec) which gives an air velocity of 239 m/sec.
I need your advise on aerodynamic behaviour of pipe, especially on vibrations considering Mach number is very close to 1.
Thanks in advance,
flame





RE: Ventilation Pipe
RE: Ventilation Pipe
I am not worried about the power demand as water will push the air through the system at normal pressure. So this is in fact air relief pipe, not a ventilation as I wrogly said.
Now my worries are exactly what you have warned, noise and perhaps vibrations. I have not dealt with pipes having to pass air at such speeds. How do I assess it? What is the better way out? As far as drag is concerned, I can take that into account in structural design.
Thanks.
RE: Ventilation Pipe
It would seem that the tunnel should be filled SLOWLY while all air is vented.
The airflow by itself can be handled without significant difficulty.
However, you absolutely must ensure that the water is not allowed near the entrance to the vent pipe if it is venting at a high flow rate. If the air/water interface hits this opening with any significant velocity, there will be a severe waterhammer that may fracture the tunnel. For an instantaneous velocity change, the waterhammer overpressure is on the order of 60 PSI/(ft/s), or 13.6 bar/(m/s).
RE: Ventilation Pipe
RE: Ventilation Pipe