Tech Talk: Ferrari's blown wheel-nuts in China
Ferrari made a step forward at the weekend to close in on, or possibly even pass, Red Bull as the second quickest team in race-trim after Fernando Alonso took third behind the Mercedes duo.
One of the noticeable upgrades was the Italian team's blown front wheel hubs. This certainly isn't a new concept, with both Red Bull and Williams using similar systems last year.
However this year, both have dropped the innovation. Not because it doesn't work, but because the FIA introduced tighter wheel-nut regulations to include a fail-safe should a wheel not be secured properly. This rendered both Red Bull and Williams solutions unusable without major redesigns - of which they're most likely working on.
Ferrari have managed to design their blown-hubs with the fail-safe included - the idea is actually believed to have come from Lotus after Ferrari signed their head of aerodynamics, Dirk de Beer, late last year. Lotus are expected to race their version soon.
The innovation takes airflow from the new enlarged brake-ducts which feed a channel running through the spinning axle. The airflow then exits out of the centre of the wheel-nut (see hollow wheel-nut above).
Without the blowing effect (see green arrows below), the airflow coming off the front-wing endplate hits the front-tyre and then, due to the curved shape of the wheel, follows the contour and is directed toward the cooling opening. This is a waste of critical flow.
By pushing air through the wheel-nut, it pushes the wake coming off the front-wing endplate further outward (see orange arrows as they meet the blue arrows). This improves the outwash effect and channels the airflow toward the sidepods and crucially, toward the diffuser.
The additional airflow also reduces drag by decreasing the low pressure area behind the front tyre and increases brake cooling efficiency.