Understanding Powder Behavior under Centrifugal Force

[Asdr]

Homework Statement

How does powder behave under centrifugal force? Let's imagine that we put the powder in a box and start rotating it. How can I understand how the powder will behave? Will it be flat and stick to the outer side of the box or...?

Relevant Equations

No equations are required. Knowing ansys probably would help

How does powder behave under centrifugal force? Let's imagine that we put the powder in a box and start rotating it. How can I understand how the powder will behave? Will it be flat and stick to the outer side of the box or...?

 

[berkeman]

Welcome to PF.

Do you mean like a rectangular box? What axis is the axis of rotation? Can you post a sketch?

And where does the "Laser" come into this?

How much powder is there in this "box"? Is it half-full? 1/10th full? What kind of powder? What is the spin rate?

 

[Astronuc]

Homework Statement:: How does powder behave under centrifugal force? Let's imagine that we put the powder in a box and start rotating it. How can I understand how the powder will behave? Will it be flat and stick to the outer side of the box or...?
Relevant Equations:: No equations are required. Knowing ansys probably would help

How does powder behave under centrifugal force? Let's imagine that we put the powder in a box and start rotating it. How can I understand how the powder will behave? Will it be flat and stick to the outer side of the box or...?

It depends on the flow characteristics of the powder.

What are the body forces acting on the powder?

 

[Asdr]

Welcome to PF.

Do you mean like a rectangular box? What axis is the axis of rotation? Can you post a sketch?

And where does the "Laser" come into this?

How much powder is there in this "box"? Is it half-full? 1/10th full? What kind of powder? What is the spin rate?

First of all, thank you for answering. I have to design an innovative apparatus that is based on selective laser sintering (basically it is 3D printing), but our idea is to make the box with powder (for ex aluminum) spin so centrifugal force will compress the powder making it denser. The laser comes from outside and should be probably directed by mirrors. We are not quite sure about the idea, we don't really know how powder behaves when the box is spinning. Overall, the goal is to make the powder flat and to point a laser beam to create a part. Idk, maybe you will have some creative solution for us)

 

[Asdr]

It depends on the flow characteristics of the powder.

What are the body forces acting on the powder?

Thank you for answering! Centrifugal force and you can assume that powder is like a fluid (water maybe, but denser). In fact, we will be using aluminum powder. Here is the design. Maybe you have a creative solution to make a powder in the box, which is spinning, flat. And how would you design mirrors so they will direct laser beams into the box?

 

[Astronuc]

Centrifugal force and you can assume that powder is like a fluid (water maybe, but denser).

Centrifugal force and gravity, and friction within the particles and on the wall of the container to be coated. How uniform will the coating be?

To aim a laser at the inner surface, one would need to aim the laser into the interior of the chamber (box) and hit a 45° angle mirror to deflect the laser beam from vertical to horizontal.

Has one thought about the traverse of the sintering laser on the surface of the box?

 

[italicus]

Homework Statement:: How does powder behave under centrifugal force? Let's imagine that we put the powder in a box and start rotating it. How can I understand how the powder will behave? Will it be flat and stick to the outer side of the box or...?
Relevant Equations:: No equations are required. Knowing ansys probably would help

How does powder behave under centrifugal force?

I imagine the powder is considered a real fluid, not a perfect one. Let’s suppose an initial omogeneous distribution into the box, and the box cylindrical for simplicity.
When you make the cylinder rotate, a thin boundary layer attached to the inside Wall rotates with it. Tangential forces are transmitted to adiacent layers, and so on.
But can one consider the fluid compressible or not? Local density could change, the powder isn’t water; do you know a bucket containing water and put in rotation? In a gravitational field, the surface of water becomes a paraboloid . But with powder things are different.
Viscosity and density play their role. Anyway a centrifugal effect is present.

There are operating machines in engineering industry , air compressors , that use energy to compress air and send it in recevoirs; between them, an important class is that of centrifugal compressors. If you want an idea about the way they work, have a look at this :

https://en.wikipedia.org/wiki/Air_compressor

mechanics and thermodynamics are involved here .