I don't have a degree in hydrodynamics, but I never understood how, on fans, you can increase airflow without adding noise, decreasing static pressure, changing airflow pattern, or flat out lying about the specs.
The noise comes mostly from the blades and airflow, not the motor. So changing blade shape can reduce noise. Some changes are inspired by nature, like trying to imitate the leading edge of an owl's wing (extremely silent in flight) when designing the blade edges. The blade shape can make or break a fan, and there's where you squeeze out the most efficiency or perfoirmance. Just look at any other place fans are used like planes or helicopters.
Because there are way more variables in there than just those. It looks like going to the 6-pole motor allows for a slower max speed, which probably means higher torque ratings. So you design the fan to run slower, but with a blade that is designed to push more air per revolution. That doesn't mean they push more air than a faster, louder design, just that they push more air than the previous version without being any louder.
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meacupla - Thursday, June 11, 2015 - link
I don't have a degree in hydrodynamics, but I never understood how, on fans, you can increase airflow without adding noise, decreasing static pressure, changing airflow pattern, or flat out lying about the specs.close - Thursday, June 11, 2015 - link
The noise comes mostly from the blades and airflow, not the motor. So changing blade shape can reduce noise. Some changes are inspired by nature, like trying to imitate the leading edge of an owl's wing (extremely silent in flight) when designing the blade edges.The blade shape can make or break a fan, and there's where you squeeze out the most efficiency or perfoirmance. Just look at any other place fans are used like planes or helicopters.
djc208 - Thursday, June 11, 2015 - link
Because there are way more variables in there than just those. It looks like going to the 6-pole motor allows for a slower max speed, which probably means higher torque ratings. So you design the fan to run slower, but with a blade that is designed to push more air per revolution.That doesn't mean they push more air than a faster, louder design, just that they push more air than the previous version without being any louder.