How can I design a laminar air flow in a particle environment?

Question

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I have a situation where I need to look at a wall with a video camera. The video camera is mounted in a dusty environment where a constant flow of particles are moving downwards. I want to use pressurized air to remove the particles in the zone ahead of the camera. How should I design a device making it possible to blow away the particles in this area. Is it a matter of using many small pipes next to each other or generating different air speeds and hence different local pressures?

Thanks for your help,

Lucas Jensen

Answer 1

What is the distance between the lens and the wall? if it is moderate, then I suspect a bundle of tubes might work well, the flow doesn't have to be perfectly laminar to just shield a lens. If the distance is quite short, I wouldn't think any special control of the flow would be needed at all However if the distance is long it becomes more of a challenge, but not knowing the distance (nor having any real experience with the subject) I can't give specific information. I think I would experiment, build a housing like your illustration, with small tubes or perhaps a corrugated sheet of thin metal or plastic as flow straighteners and just try it with various air flows.

Answer 2

It is highly unlikely you will achieve laminar flow using air, unless the velocity is extremely small (say, 1 cm/s), or the characteristic length scale is extremely small (a few millimeters across). Your situation has neither of these things, so turbulent airflow is much more likely.

However, that is not a problem. If you need to blow dust away, or at least make it move quickly enough that the video camera won't see it, why not use an ordinary fan?

Answer 3

Why not pull the particles toward the area above the camera then exist them out below the camera?
Just use very high volume, low velocity movement.
This should create a sideways U-shape particle movement.
If you blow air out, It will hit the wall and create turbulence cause even more dust to re-circullate.
Let me know how it works out.

Answer 4

we have a simple Hood with a fan and HEPA filter and get class 100 clean for particulates >.5 Micron