A Quick Guide To: Diffusers

Diffusers, most commonly heard of as the RBR pioneered ‘double diffuser’, have been a hot topic over the past few seasons. But what actually is it, and why do F1 cars need one?

read on for more :)

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Before we go into what the ‘diffuser’ component actually does, we need to understand how it links to the rest of the car. The diffuser (see top right picture) is located on the rear underside of the car, and so the concepts engineered around it link directly to the floor of the car. 

The Venturi System

The floor of an F1 car may look flat and uninteresting but it is actually a very complicated structure. It is the most efficient downforce-producing component on the car (the force the air exerts on the car, pushing it onto the road and giving it more grip and stability). The added benefit is that the floor has the minimal drag effect on the car.

But how does it create downforce when it’s already beneath the car, may you ask? 

The floor, together with the front wing and rear diffuser, forms what is called a venturi. In its simplest form, a venturi is a tube with the middle bit squished! Here is a pretty gif

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The surface of the track acts as the squished bit in the middle of the tube, and the air flows under the floor of the car and out the other end. 

The area where the air enters into the tube is called the ‘inlet’, the squished bit is called the ‘throat' and the area downstream of the squished bit is called- no prizes for guessing- the diffuser!

When air flows through this venturi, aka underneath the floor of the car, the air accelerates as it enters the throat, and the pressure of the air drops. This pressure will be lower than the pressure on top of the car, therefore downforce has been created! 

So the main aim of the diffuser on an F1 car is to direct the flow of air out of the back of the venturi floor system, and thereby producing downforce, which decreases laptimes and increases handling capabilities of the car.

On the car

Diffusers are made from carbon fibre, and can produce 30-40% of the total downforce on a car, if designed properly! 

When the diffuser is viewed from the rear, you can see a number of vertical stakes. These are designed to ‘clean up’ the airflow and make it tidy as it exits the diffuser, to help maintain the aerodynamic efficiency. 

Unlike the front and rear wings, the diffuser is not adjustable, although changes to the ride height of the car can affect the performance of the diffuser. 

So that’s the basics! There are plenty of clever engineering tricks teams have played with the diffuser. Adrian Newey has been the front runner in pioneering new ideas and a post on double/blown diffusers is coming soon! :)