Technique: Red Bull exhausts

Despite the new rules concerning them for 2012, exhausts have maintained importance, particularly in the diffuser’s efficiency. Indeed, when properly guided between the tires and the ends of the diffuser, the exhaust gas flow, expelled at over 800 km/h and at high temperature, thus containing significant energy, can “seal” the extractor, meaning it prevents the high-pressure air from “leaking” out the sides (read our article “L’aérodynamique pour les nuls”) and thus reduces the efficiency of the diffuser.

Red Bull and Ferrari certainly haven’t been fooled, working tirelessly by testing numerous configurations throughout the beginning of the season. The Austrian team continued its efforts in Valencia with a new version that synthesized different solutions already observed in the paddock. A version that has been improved for this British Grand Prix (photo opposite, which you can find in high definition in [our Friday album](https://website-url), and diagram below).

Indeed, the new design, itself an evolution of the one that appeared at the Barcelona tests, achieves a triple effect. It features a hump (orange on the diagram above) borrowed from McLaren, which has been raised compared to the Valencia version (in the bottom left box), allowing better guidance of the exhaust gases in the direction of the exit (red). This hump is extended by a kind of launch ramp (dark blue) inspired by the original Sauber exhausts, which directs the flow between the tires and the diffuser (in blue in the top box) to effectively seal it. Finally, beneath this launch ramp and in continuity with the hump, a duct is carved, imagined by Adrian Newey’s technical teams.

This duct is divided into two parts by a small carbon piece that serves as a separator (light blue). The first part (yellow) leads to an opening (yellow in the top box) that allows air to be directed over the diffuser. The second part (green) ends with the only permitted hole in the diffuser (green in the top box), whose primary use is to allow the starter to pass through, but which is diverted here for purely aerodynamic reasons: as the section of this part of the duct narrows, the speed of the flow inside increases and its pressure decreases. Therefore, the air exits more quickly and consequently accentuates the differences in air speed and pressure on either side.

Without this duct, as was the case with Red Bull’s pontoons in Bahrain, the airflow circulating along the sides of the pontoons (purple lines) could not reach the diffuser because the high-speed exhaust gases, acting as a barrier, would prevent it. And when it was present before Bahrain, part of the exhaust gases, which was not properly directed due to the absence of the bulge, passed through the duct, causing a significant loss of diffuser efficiency during re-acceleration, as low-pressure, high-speed air was suddenly injected into the diffuser. Blocking the duct was therefore only a temporary solution, allowing for a bit of stability during acceleration, while redesigning a duct where much fewer exhaust gases would flow through.

And so, Red Bull theoretically finds itself with the best of the three models it was inspired by: the diffuser is effectively blown, as the gases are guided by the raised bump and launch ramp, while allowing it to be fed by the air passing above (pink lines) and on the side of the pontoons (purple lines, via the first part of the duct, in yellow), without the exhaust gases passing through the duct.