Affinity laws

Affinity laws are kind of like rules that tell us how different factors affect each other when we're talking about pumps or fans. Imagine that you have a fan that you can adjust the speed on. There are three things that will change when you turn the fan up or down: the flow rate, the total head, and the power required to run the fan.

Let's start with flow rate. Flow rate is how much air the fan is moving – like how much it's blowing on you if you're standing in front of it. Affinity laws tell us that if we double the speed of the fan, we'll double the flow rate. If we triple the speed, we'll triple the flow rate. So, as the speed goes up, the flow rate goes up.

Next, let's talk about total head. Total head is the pressure that the fan is creating, kind of like how hard it's blowing on you. Affinity laws tell us that if we double the speed of the fan, we'll quadruple the total head. If we triple the speed, we'll increase the total head by a factor of nine. So, as the speed goes up, the total head goes up even more.

Finally, let's talk about power. Power is the amount of energy that the fan is using to run. Affinity laws tell us that if we double the speed of the fan, we'll increase the power required by a factor of eight. If we triple the speed, we'll increase the power required by a factor of 27. So, as the speed goes up, the amount of power required goes up a lot.

Overall, affinity laws help us understand how different factors are related when we're working with pumps or fans. We know that as the speed goes up, the flow rate and total head go up, but the amount of power required goes up by even more.