The fan on a PS4 is a blower type fan that you often see in laptops.
Cold air is drawn through the back of the PS4 and exhausted out by vents on the front of the Ps4.
Because it works 45 degrees to a normal fan you find in a pc or a tower case for a 120mm fan.
If placed directly in the right position above the blower type fan it forces a higher volume of air down to the blower type fan of the PS4.
The static pressure is in creased in in Cmf is increased greatly.
The faster you can force cold air at a higher speed or flow rate the better the cooling effect is on the Gpu or cpu of the console.
Much like ramping the fan speed up in rpm of a fan fitted to a cpu cooler of a pc.