Dead Leg Calculation - extent of turbulence 1

[wobblybob]

Hello All,

I have a water cooled vertical pipe, 4 metres high and 200mm bore. The bottom of this pipe is blanked off. At the top of the pipe, water is delivered by a 25mm bore inlet at 34 litres per minute (1.15 metres per second). The outlet is also at the top.
Does anybody know how to calculate the extent of influence the moving water has on the rest of the pipe, i.e. the length of dead leg existing in the pipe.

Thanks is advance,

Bob

 

[wobblybob]

Just to make things clear.

This is not the design of the vessel. The situation has arisen out of a mistake in manufacture. The feed pipe should have been extended to the bottom but was forgotten.

Thanks,

Bob

 

[BRIS]

Temperature difference (density) must be the controlling factor.

If there is no temperature difference I guess the length of mixing will be very shallow. Need to look at the diffusion of a 25mm dia jet at a velocity of 1.15 m sec. I have a good reference somewhere - will get back on that if nobody provides an answer in the meantime.

 

[wobblybob]

Thanks Bris,

The temperatures involved:

Inlet temp approx 15 celsius
Pipe temp approx 50 celsius

Bob

 

[BRIS]

Based on diffusion of submerged jets (Albertson ASCE 1948) the physical penetration of the jet due to the velocity will only be some 200mm.

Temperature diffusion/thermodynamics is the control but is not my field.

 

[wobblybob]

Many Thanks, Bris.

Much appreciated.

Bob