Other teams began to roll out their own solutions once they had understood the aerodynamic benefits, placing their exhaust tailpipe in similar positions.
Although Red Bull had a head start over its competitors, the team had also put in a great deal of work with engine supplier, Renault, enabling it to extract even more performance through off-throttle blowing.
By clever manipulation of engine maps, Red Bull and Renault were able to ensure that some degree of airflow was still being expelled from the exhaust outlet to retain the seal on the diffuser - even when off-throttle. With that, the blown diffuser's main bugbear was eliminated as downforce was still being created during all phases of cornering. The FIA sought to discourage this practice, moving to change the regulations about the location of the exhaust for But this simply inspired F1's great technical minds to enact a workaround solution - and three different designs immediately emerged to try to counteract the new requirements.
The two most extreme solutions to arrive were from McLaren and Lotus, as they routed the exhaust within the sidepod to try to place the tailpipe in a position where they thought they'd gain the most aerodynamically. In the case of McLaren above , the fantail solution had a nozzle that was mated to the floor and blew through a long slot on its edge. It was supposed to act much in the same way as a skirt, creating a seal between the floor and the track. Not all good ideas work in the real world though, and this one didn't even make it through testing, as the team struggled with heat management issues and the rigidity of the exhaust against the flexibility of the floor.
McLaren had initially struggled with exhaust-blowing throughout , as the positioning of the outlets meant that the exhaust gases initially clung to the contours of the car, rather than pouring out to the corner of the diffuser. Meanwhile, Lotus opted to stretch the exhaust outlet all the way to the front of its floor. Its front-facing exhaust solution had shown promise when tested against other designs pursued by the team and also proved less susceptible to changes in throttle, resulting in an initially easier car to drive - but didn't stand up to the development of other teams and quickly fell down the order.
Meanwhile, Red Bull had come up with a less complex design that was swiftly followed by the rest of the grid. It created wide, low exhausts that sat on top of the floor and exited into the channel between the side of the tyre and the outer diffuser wall. This solution would help to mitigate a problem known as 'tyre squirt', in which jets of air are pushed laterally into the diffuser's path produced by the tyre's rotation and flex under load.
F1 teams and the FIA were once again set to be at loggerheads over the course of the coming races, with the latter unamused that the engine was technically being driven without command from the driver. It seems that cold-blowing, as it became known, was considered a borderline but acceptable tactic by the FIA.
This exhaust-blowing trick was achieved by cutting the fuel and spark and, combined with cylinder cutting, turned the engine which was still being revved into an air pump and was able to power the diffuser when off-throttle.
A practice that subsequently entered circulation was hot-blowing. This involved retarding the ignition and manipulating the torque maps in order to get a more potent gas plume to power the aerodynamics. Hot blowing wasn't viable over a long period, as it increased fuel consumption and affected the engine's lifespan. But used sparingly it could offer a tangible performance advantage. The FIA sought to reign in the practice and was set to introduce an in-season ban.
But, following lobbying from the teams, it instead altered the regulations to not only prevent off throttle blowing, but also rule out the floor mounted blown diffuser solutions.
This probably helps keep unwanted heat from the tires. But in Canada, where tire temperatures were low, this fence was removed. It could be that the tire heating effect could be a tunable parameter, by varying the heat shielding around the coke bottle area. Of course, other teams want to dissolve RedBull advantage, and start to develop their own blown diffusers. McLaren and Williams are expected to follow for the next race At Silverstone. Ferrari, Renault and Mercedes start the race with a diffuser blown only over the top, without window, which perhaps offers less potential then a through blown diffuser, but at least will be legal next year when double diffuser is banned by new rules, and preventing openings in the diffuser.
The blown element operates independently of the "double" element of the diffuser and whereas double diffusers are banned from next season, the blown diffuser is here to stay. On the end of season, Ferrari perfected their own blown diffuser. In the place of vertical windows used by RedBull racing RB6 racer, Ferrari employed horizontal slots over the top of diffuser.
A blown diffuser increases downforce on all corners , with the greatest effect on medium to low speed corners. It becomes increasingly less effective the faster the car goes. That's the reason why is Red Bull so strong on the tracks with medium speed corners.
BTW, Red Bull Racing clinched both the constructors' championship and the drivers' crown with Sebastian Vettel, with the victory in Abu Dhabi, the last race of season and Vettel become Formula 1's youngest-ever world champion, only 23 years old. This is all the proof that is needed about how good the outfit is now, with Adrian Newey as technical director and main designer.
In the top teams focused a lot of resources on extrapolating aerodynamic performance from their car's exhaust gases. By channelling the gases through the diffuser the teams boosted rear downforce and they also developed engine maps that meant the gases continued to flow even when the driver was off the throttle. For season FIA has outlaw blown diffusers and teams are forced to run with periscope exhausts.
Formula 1 teams have been told that there will be stricter limitations on engine mapping next year, as part of a clampdown by the FIA to prevent teams exploiting exhausts gases. With the FIA keen to ensure that off-throttle blowing of exhausts does not continue, the governing body has issued a Technical Directive to teams informing them that there will now be severe limitations on what is allowed next year. FIA has made it clear that the version of the software used by F1's standard ECU will now put certain limitations on engine mapping.
Although the positioning of exhaust tailpipes will be more tightly controlled, there is still some potential for off-throttle engine mapping to be heavily exploited. Although the FIA move was not delighted all teams, with some expressing reservations in a meeting of the FIA's Technical Working Group, the majority of outfits have welcomed the move - because it effectively removes a grey area of car development.
The FIA argued earlier this season, during an intended push to ban off-throttle blown diffusers which eventually had to be abandoned, that such extreme engine maps were a breach of the famous Article 3. This was based on its view that there was an aerodynamic benefit from a moveable part engine and throttle , plus it was being influenced by the movement of the driver through the throttle.
Neither are allowed in the rules. This new hanges to the technical regulations have thrown things back into the melting pot and it remains to be seen who has done the best job of re-interpreting them. Change in exhaust exit pipe position, diameter and profile led to loss of rear-end downforce, sending aerodynamicists searching for fresh ways to regenerate it and rebalance their cars.
New positioning of the exhaust pipes exits and limitations are shown on picture below. Exits of the pipe can be positioned inside green box with exhaust tailpipe pointed upwards. But this was not sufficient to eliminate exhaust-blown diffusers.
Well, the first thing to note is that it is not possible to point the exhaust exit down at the diffuser in same way as before, this will not necessarily prevent the exhaust jet itself from blowing in that direction.
When an exhaust jet exits into a cross-stream of fresh air, the exhaust jet bend with the air stream, effect called "Downwash". If the exhaust exit is placed flush in the rearward face of sidepods sweeping downwards at a fairly steep angle, then the free stream airflow could deflect the exhaust jet downwards in direction of the diffuser.
The degree to which the jet is deflected is determined by the ratio between the velocity of the jet and the velocity of the cross-stream flow. The smaller the ratio, the more the jet is deflected. Basicaly, coanda effect dictates that gases will stay attached to a surface they are directed along. Of course, secret is to design this part of the bodywork and bodywork in front of the exhaust exit in the way to optimize this effect and give a proper and exact route for gasses to flow in direction we want.
Effect of diffuser blowing is not as strong as before, but with clever design and optimization you can get few percent of download more. With this set up the exhaust plume is curved downwards by both the shape of the bodywork aft of the tailpipe coanda and by the airflow passing over the sidepod downwash.
During pre-season testing, already few teams come with this new solution. Sauber Racing and McLaren found a way of shaping the sidepod and exhaust fairing to use these effects. They where able to consistently direct the exhaust jet at the gap between the diffuser and rear tire. Lotus was the last team to follow the trend for the Coanda-effect exhaust system, introducing it from Friday in Korea GP on Kimi Raikkonen's car, providing exhaust-boosted airflow over the rear brake ducts and around and over the diffuser sides.
Kimi continued to use it in qualifying and race, while team mate Romain Grosjean kept the old, central-blowing exhaust, which provides slightly more engine power. This leaves just Red Bull following the fully ramped sidepod design, and HRT remain with a simple periscope exhaust set up. Diffuser has low pressure inside, this will draw in high pressure airflow from outside the diffuser reducing its downforce.
Unable to blow directly into the diffuser since the rule changes, the gases are guided down channels inside the rear wheels, sealing the gap between the tires and the outer side of the diffuser and this serves as skirt to seal the side of the diffuser from leakage. Having the exhaust blow along the diffusers edge keeps these pressure regions separate and prevent the tire squirt upsetting the diffuser. Preventing these effects means the diffuser creates higher levels of downforce at the high rear ride-heights and large degrees of car rake and is more efficient.
During , last year before radical changes in engine , exhaust and ERS , Red Bull, Lotus and Sauber were the only teams who have their rear bodywork designed and optimized in such a way as to guide the exhaust gases all the way down to the area they want them - and Sauber have only done it in the last couple of races. Other teams tried to follow their lead, but with more or less success. As far as I can see it, during , and , Vettel was only person who drives in a fashion aimed at using this to best effect.
The rest of the field have it on their cars but have not adapted their driving style to use it as well as possible. And system itself was not as good as Red Bull's. Without doubt they push everything in this area to the limit but that is there for everyone to do. Vettel go with the fact that it will give him more rear grip if he nails the throttle very early after apex , so he does that.
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