Five F1 tech talking points of 2017: Wider scope for diffuser development

Our final Formula 1 technical round-up of 2017 ends by focusing on the rear of the car, as we delve into the diffuser development across the grid.

The diffuser is an important part of the aerodynamic structure of an F1 car, which contributes a significant amount of downforce. So as part of the new ruleset, the diffuser width and height was expanded by 50mm in the FIA’s efforts to get the cars going four to five seconds per lap faster. The point at which the diffuser throat was introduced was also moved forward – ahead of the rear axle – to increase the worked volume further.

Increasing diffuser volume helps to develop a more pronounced pressure differential between the top surface of the floor and the underside of the car, providing a greater boost to rear-end downforce.

Here is a short insight into some of the ways that the 2017 grid maximised their overall diffuser performance.

Red Bull’s rakish looks

For a number of years, Red Bull Racing has pursued a very aggressive attitude to the rake angle of the car, keeping the front of the car as low to the ground as possible while keeping the rear high to maximise the volume of air under the car.

Using the front of the floor as a point to accelerate the airflow, the underfloor is then able to generate greater areas of low pressure, improving the overall downforce characteristics of the car.

Although such a design, if not implemented correctly, can result in separation of airflow attachment – and hence producing an inefficient floor – Red Bull’s honing of this concept over the past few seasons has allowed the team to run more extreme rake angles.

This is also an example of using other parts of the car to maximise floor performance, and Red Bull has also made a large amount of progress in defining its bargeboard designs to assist with sealing the floor, ensuring that the larger exposed volume under the floor is not unsettled by turbulence.

Thanks to the successes of Red Bull’s extreme rake philosophy, it has become a design feature that Mercedes has suggested will appear on next year’s car.

Ferrari and Mercedes show different philosophies

The two 2017 title protagonists Ferrari and Mercedes offered different solutions to the 2017 diffuser regulations, each seeking to find the maximum performance at the rear end of the car.

Mercedes used a squarer design, with a slot to the rear in order to combat separation in the underfloor flows as the diffuser ends. With separation, a vortical region is created which cuts the effectiveness of the diffuser, producing a drop-off in downforce.

Ferrari, on the other hand, used a more bevelled design to interact with the numerous elements around the rear axle. This offers a greater platform to clean up the rotational flows associated with the wheel movement, which can have an adverse effect on the pressure distribution around the diffuser.

In preparation for 2018, Ferrari trialled a design solution in practice for Abu Dhabi more similar to Red Bull’s diffuser design, which uses a slightly more sculpted exit - with broken up strakes on the diffuser sides - to manage the flow produced by the rear wheels.

This has also increased the volume of the diffuser, offering the potential of more rear-end downforce.