Bending the Limits Part 2

As stated in the previous post, aerodynamical adaptions are a very efficient way of boosting a vehicles performance. The following technique is a lot more complicated than the bio-mimicry discussed before, however this method holds great promise. The biggest difference is that one should make a whole lot of adaptions and is not something just anyone can accomplish. The technique is called ‘Boundary layer suction’.

Without going into too much detail, the boundary layer is the region closest to an object wherein the speed internally differs. In other words, one ‘layer’ of air has a different speed than the layer immediately above or below it, which results in viscous friction. This flow in general is closely attached to the surface and doesn’t let go, however, this layer can separate from the surface and causes a large increase in drag. This happens for example when the angle of attack of a wing becomes too high and stall occurs.

sans-titre-2500ddb

The idea behind boundary layer suction is that one sucks away this layer before it has the chance to separate. This not only increases the extent to where the flow stays attached, one also is able to extend the range of the laminar flow, decreasing the drag even more. However, this suction also costs energy, so one should try to calculate the net gain in energy before considering this technique. It holds great opportunities for aerospace, but would it be something also applicable to cars as well?

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2 thoughts on “Bending the Limits Part 2

  1. Is there really a lot of gain still to be made by further aerodynamically optimizing cars? One would think that rolling resistance also accounts for a lot of the energy required to keep driving, no?

    • Rolling resistance does account for a lot of the losses, that is indeed true. And thus, there can also be gained a lot from improving this. However, during my team in the solar team, the aerodynamic losses of our car made op 65 – 70 % of the total losses. Keep in mind that that car was very aerodynamical which can’t be said of the nowadays cars. Truth be told, our car also weighed a lot less in comparison to other cars and therefor other cars have a significantly higher rolling resistance compared to our car, but that is why the use of a monocoque structure (as discussed in previous posts) would already be a step forward to solve this. So in my opinion, there is definitely a huge gain to be made aerodynamically.

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