Apple unveils the all-new Mac Pro and Pro Display XDR

[matts-uk]

I'm sure the designers of the fan have their reasons whatever it is, hell it could just be they found most of the 'air noise' was coming from near the hub and blocked it off lol.

Apple cynicism remains high I see (pun intended). Within the discipline of impellor design the hub is called the 'eye' and a larger eye is proven to reduce the volume of material (air in this case) that the impellor ends up recirculating.

It is a loooonnnng time since I had to do rotational velocity calculations for impellors and propellors but as far as I remember... The basic principle is that for a single revolution a point on the edge of a disk travels a much longer circumference than a point near the centre on the same radius. For both tip and root of a fan blade to start and end the revolution at the same time (which they must), the tip must travel significantly faster than the root. Convert the velocities to pressure and all other things being equal, there is a standing pressure gradient that rises from the edge of the eye (low) to the tip of the blade (high). Hence, a larger eye reduces the pressure differential and hence the volume of air that ends up being recirculated near the root as the 'system' seeks equilibreum.

I would agree that Apple has lost it's way since Jobs' passing. Like him or loathe him Jobs was a technology visionary, as proved by the two stints at Apple and the one at Next Step. Tim Cook is not a visionary of any sort - He is an accountant(!)

[3dcandy]

Apple cynicism remains high I see (pun intended). Within the discipline of impellor design the hub is called the 'eye' and a larger eye is proven to reduce the volume of material (air in this case) that the impellor ends up recirculating.

It is a loooonnnng time since I had to do rotational velocity calculations for impellors and propellors but as far as I remember... The basic principle is that for a single revolution a point on the edge of a disk travels a much longer circumference than a point near the centre on the same radius. For both tip and root of a fan blade to start and end the revolution at the same time (which they must), the tip must travel significantly faster than the root. Convert the velocities to pressure and all other things being equal, there is a standing pressure gradient that rises from the edge of the eye (low) to the tip of the blade (high). Hence, a larger eye reduces the pressure differential and hence the volume of air that ends up being recirculated near the root as the 'system' seeks equilibreum.

I would agree that Apple has lost it's way since Jobs' passing. Like him or loathe him Jobs was a technology visionary, as proved by the two stints at Apple and the one at Next Step. Tim Cook is not a visionary of any sort - He is an accountant(!)

Jonny Ives gone as well...

[Xlucine]

Apple cynicism remains high I see (pun intended). Within the discipline of impellor design the hub is called the 'eye' and a larger eye is proven to reduce the volume of material (air in this case) that the impellor ends up recirculating.

It is a loooonnnng time since I had to do rotational velocity calculations for impellors and propellors but as far as I remember... The basic principle is that for a single revolution a point on the edge of a disk travels a much longer circumference than a point near the centre on the same radius. For both tip and root of a fan blade to start and end the revolution at the same time (which they must), the tip must travel significantly faster than the root. Convert the velocities to pressure and all other things being equal, there is a standing pressure gradient that rises from the edge of the eye (low) to the tip of the blade (high). Hence, a larger eye reduces the pressure differential and hence the volume of air that ends up being recirculated near the root as the 'system' seeks equilibreum.

I would agree that Apple has lost it's way since Jobs' passing. Like him or loathe him Jobs was a technology visionary, as proved by the two stints at Apple and the one at Next Step. Tim Cook is not a visionary of any sort - He is an accountant(!)

You convert the velocities to pressure via the angle of attack (and coefficient of lift of each blade section), hence the higher geometric pitch on fan blades as they near the hub to flatten out the pressure gradient. Granted it's not a 1:1 relationship between AoA and geometric pitch, due to the different inflow (and even assuming constant inflow velocity then hydrodynamic pitch increases towards the hub), but the pressure difference between the root and tip is more than just a function of blade speed