Blower fans have more pressure, that is why they are used, they can accelerate much more the air, this also brings more noise, because the same air volume is being compressed through a smaller outlet! Also, you need to find if your outlet has a more turbulent or more laminar flow. Usually, more noisy, more turbulent. A constriction in air flow creates a turbulence. But if the centrifugal fan is well done, it has a more laminar output then the axial one. Also, if you put an air filter, or more complex air pathway, axial fan will lose much more performance then the centrifugal.

I'm going to conjecture that the axial fan's blades stall (since they're aerofoils) when the outlet is blocked, leading to a huge increase in drag due to the turbulent air, which in turn slows the fan and uses more power. In contrast, the centrifugal fan does not use aerofoil blades and therefore cannot stall, and the fact that it is moving less (no) air means that it needs less power to do so, and speeds up.

Centrifugal blowers were always used for air cooling of large radio transmitter ceramic vacuum tubes (ignoring water cooling). If you Google image search 4CX250 or YC-156, you will get an idea of the constricted airflow heatsink design as well as the pressurised air box used to facilitate air flow through the fins. Cooling requirements are specified in the tube datasheets, and are specified in cubic feet per minute (CFM) as well as inches of water back pressure, using a manometer. You can construct a back pressure test rig using a shoe box, and a water manometer can be made from plastic tubing. This test would show the pressure difference between blower and axial.

Done hvac 20 years. This is the same with blower motors. Ppl thunk that if u were to have super dirty air filters, coils crushed return vent etc that it will make the amp draw go up. WRONG. It cuts the amo draw down by like a third. The air is no longer blowing through the blower and out the outlet it is no longer moving air and spinning with very little load. The air is coming from the side and just moving round and round with nowhere to go

I have a Asus RTX 2080ti Turbo. The blower fan can get the job done. But it is mutch more loud than a oprn card would be.

Many years ago i was helping a friend with a car that kept over heating. He had a large electric fan that moved a HUGE volume of air very quickly. I suggested he replace it with one that moved the same volume but at a slow speed and then proven went away. The issue wasn't how much air that was being moved but how long it was in contact with the radiator. The slower moving air was able to pull more heat away for the same volume than if it was rushing through the fins faster. This is the same thing I look at any time I'm selecting a fan. Faster or more isn't always better.

The unrestricted blower fan wil move a lot of air, but once the exhaust is blocked the air cannot move trough the fan. Thus the blades 'see' no load and are able to speed up to the maximum possible rpm for the given voltage. The only load the centrifugal fan needs to overcome is the weight of the motor and blades + some minor eddy currents that form at the inlet. A centrifugal fan behaves like a pump, by moving air from one end to the other a pressure difference is created and the surrounding air will naturally move towards a vacuum. The axial fan (airfoils basically) is designed to efficiently move a lot of air (lift) per rotation and cannot handle large pressure differences. Putting the axial fan on the table, the blades will see a lot of resistance from the blocked flow. The table is fixed so the only thing that can now move is the fan itself, the fan will try to move upwards but must overcome its own weight. Power will increase to the point of wire resistance (voltage divided by resistance) or to a point where pressure on both ends is equal. Axial fans do have design variations to handle pressure, but these are considerably louder compared to a similar sized centrifugal fan.This is why you see large turbo fans on commercial jets, while fighter jets have small turbo fans to be able to achieve higher speeds.

I just wonder how quiet a modern one would be. People always bring up how loud they were in the early 2000s... but cmon.. PC part makers DIDN'T CARE ABOUT NOISE back then 😅. It only makes me _more_ curious how a modern PC blower would've sounded if they had stayed more popular and had gone through the same technological advancements.

Let’s say the heatsink area is 8x8cm and you want the fan to blow over the whole heatsink. Wouldn’t you want a larger blower fan/smaller axial fan? How do two fans of the same exhaust opening size compare?

My view when differentiating centrifugal and axial fans is in terms of air flow, I choose centrifugal fans because of their extraordinary suction power and very strong bursts of air, but if we look at them from a design perspective, I prefer axial fans, because axial fans often compete in making designs, even though the air flow is not as strong as a centrifugal fan. Therefore, my collection mostly collects axial fans.

Can you provide the part number of the blower fan! I plant to use it to boost the cooling of my laptop

Blower fans are great when you need to push or suck air through a filter

That's interesting and not sure why the difference in behavior, looking forward to blower vs axial fan video.

Loving these vids. Oh wow I almost forgot about blower fans xD, interested now. Also pls test a phanteks t30 : )

What happens when a blower sucks??

You should try sleeve bearing centrifugal fan

no front but i just wanna have some hard numbers which fan will blow out 200w at 900rpm the most effectivly

I had a blower fan graphics card on my PC in 2005, never ever will I have a blower fan on anything again because the sound it made was so bad that you had to use ear protection when running the PC... I now use silent 14cm noctua fans and some 12cm fans where it was not room for 14cm, and also a large 25cm fan. Bigger the better, more air flow for less sound.