When I first started writing about blowers, it was a revelation to me that fluids like air move only from areas of high pressure to low pressure. To someone without a background in physics, fluid dynamics can be confusing and counterintuitive. But if you think about blowers and how they work, it can be helpful in understanding fluids and how they move around.
Let’s start with a very simple example. Hold out your left hand. Now, with your right hand, straighten your fingers and fan your right hand. You should feel the air moving over your left hand caused by the movement of your right hand. Why does this happen? Have you ever thought about why it happens? “Sure,” you might be thinking. “It just makes sense. That’s what happens when you fan something.” But why does it happen? What’s happening is that as your hand moves back and forth, it causes the air around it to become pressurized. One of the realities of fluid dynamics is that a pressurized fluid seeks equilibrium with nearby bodies of fluids with different pressures. In other words, air pressure is constantly seeking to equalize itself. The expression of this reality is that air flows from areas of high pressure to low pressure. When you pressurize the air by moving your hand, what you feel on your other hand is the highly pressurized air moving to an area of lower pressure, which is the rest of the room. The movement of your hand influences the direction of that flow, and your other hand happens to experience that flow.
A blower is like a bunch of hands connected to an axle or axis. They function the same way as the hand, except on a much larger scale.