2 Phase Air Flow in a Tube, research material?

[Helepolis]

Hello all,
As part of a larger experiment, we are running a two-phsee (apologize if the term is wrong) Poiseuille air flow throug a tube.
We have a main (glass) tube that goes through a fitting with a small nozzle in the middle (see attached photo).

The main flow of air flows through the main glass tube (as already mentioned the flow is a developed Poiseuille flow) at low Reynolds number (laminar flow Re<300) with flow rate of x1.
At some time point, a measured jet (bolus) of air is injected through the nozzle with flow rate of x2.
The bolus was marked with fluorescent tracer particles.

We ran several experiments where x1=x2, x1<x2 and x1>x2.
We noticed that no matter what we did we had trouble maintaining the bolus tightly packed, it got dispersed (to some extent, depending on the parameters set) as it exits the nozzle tip.

The nozzle's length is such that the air flow of the bolus is developed at exit and the main flow is settled after passing the entrance of the nozzle to the main pipe.

I would apriciate some ideas on how to reduce the bolus dispersion (different nozzle types) and refranses to research material.

 

[MikeHalloran]

Since there's no liquid, it's not two-phase flow, as normally understood.

A gas is going to mix with another gas just by means of diffusion.

To try to keep the flows separate, match the velocities at the point of injection.
I.e., match the bulk velocity of the injection nozzle to the core velocity of the flow around the nozzle, assuming the injection nozzle is considerably smaller than the larger lumen.
I'm also assuming that the injection nozzle enters the larger lumen upstream, and is bent downstream so that both flows are going in the same direction at injection.

Try again to attach your photo; I may have misunderstood the problem absent same.




Mike Halloran
Pembroke Pines, FL, USA

 

[rb1957]

how turbulent is the flow around the nozzle (injecting the bolus into the stream) ? at the same speed there should be not much mixing of the flows.

another day in paradise, or is paradise one day closer ?