This article however moves to further explain both the reason for the Tunnel and the other components that go to exploit it's potential.
Starting at the front of the sidepod Red Bull have simply converged on the idea of airflow strakes above the sidepod in order to create vortices that energise the flow over the sidepod toward the exhaust plume
The original Sidepod Tunnel concept had a cutout in the sidepod ramp with a linear height of 50mm from the floor which utilizes the minimum radius rule. This concept had the Tunnels airflow exit just aft of sidepod ramp in order try and assist the airflow toward the coke bottle region. Red Bull have experimented with other iterations exiting inside the engine cover in the same way their new tunnel/duct system works but have always had a problem with airflow attachment.
Two theories are emerging in regard to the nature of the 2 ducts and whether the larger tunnel entrance combines with smaller entrance to form a larger airflow pattern as described below:
The image above shows that Tunnel 1 has a step as it enters the duct, this allows the airflow to merge with Tunnel 2's airflow and rotate the stream. This creates a spiraling vortex inside the ductingspeeding up the airflow and removing an element of the boundary layeras the air speeds through the tunnel. The tunnel acts like a Venturi tube with the entrances being the inlet, the duct speeds up the airflow as the duct creates the 'throat' and the lower engine cover exit or starter hole isthe outlet. (See Image Below)
This Tunnel section adds a new dimension to the airflow pattern giving the airflow from the exhaust plume a further means of interacting with the diffuser. Without the means of a better way of describing it, this concept adds another deck. Although not in the same direct way as the original DDD's (Double Deck Diffusers) as it's not part of the diffuser itself, it will increase the effectiveness of the diffuser.
As we can see below from the Australian spec RB8 the original intention was that the airflow from the exhaust and tunnel would converge above the floor and exit through the centralised starter hole.
As we can see below with the current iteration of the engine cover and internal ducting the air is still directed through the starter hole but no external airflow has interaction with this airflow
Driveshaft Fairing / Cowl
The other aspect we must look at for Red Bull is their usage of a cowl for their driveshafts, they have covered their driveshafts in the same way all the teams do with the suspension components. This is not a new feature for Valencia but the effectiveness of the new Tunnel/Duct system is utilised with the combination of this component. This has a many effects on the airflow:
- Creates another element in which to turn airflow and manage the airflow coming over the bodywork towards the rear of the car.
- Encloses the driveshaft, this removes the Magnus Effect on the exterior airflow. The Magnus effect can create lift something you want to reduce in this area as it will have an impact on the air you are trying to generate downforce with. More importantly though due a massive boundary layer build up it can create a huge chunk of drag too. Not being able to divert the exhaust gases in a precise manner means you would like to control the airflow aft of the exhausts as much as possible. Reducing the effects of this spinning element from the equations especially in such a critical area may be a shrewd move by Red Bull.
I believe that all of these factors in combination are the reason for Red Bull's leap in performance. They also tie in to the decrease in tyre wear that Sebastian and Mark had at Valencia. More rear downforce = a more stable rear end and will help reduce tyre degradation. This current configuration has only been developed due to Adrian Newey and Red Bull's determination to make the original concept work, meanwhile they have inadvertently come across a much stronger version of the original concept. If we see the strakes, floor and driveshaft cowls as one unit they give the appearance similar to that of the diffuser below which should enhance the diffusers airflow profile. I hope for the sake of the close championship battle we are currently seeing that the other teams already have similar concepts in development. As this in my eyes is not simply a one off for Valencia and will continue to provide Red Bull with a large gain over the other teams.
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