flboy wrote:I think the large truck pulling you over and pushing you out aren't as much about the airflow around and over the trailer as much as they are about the low pressure area behind the trailer (which the vortex generators affect).. At least that is the way I understand it. I am not thinking about efficiency in this case.
Maybe someone can explain it better, but as the truck approaches from behind it is pushing air causing a higher air pressure and the low behind the trailer is attracted, the opposite when they pass by with the low pressure behind them and high in front of me..
Certainly crosswinds stability is affected by the surface area and profile, but I am think specifically of that sucking in and pushing out semi trailer and large buses create when they pass by me in the same direction of travel when I am towing the CTC
Anybody?
Don,
I think you bring up a good discussion point. It makes sense that if you reduce some of the drag/suction at the rear of CT, then the push and pull of large passing vehicles should also diminish.
This website has a brief description of ideas to reduce trailer drag: [urlhttp://www.part20.eu/en/applications/trailer/[/url]. They're not too aesthetic but the vanes applied to the sides and top of the trailer seem to be pretty effective in reducing the negative pressure at the rear of the trailer. I think this is the concept of air tabs.
Another random thought came to mind would be trying out "Gurney flap" or "wickerbill" on the sides or top of the trailer. A cheap way of trying this out would be to use metal roof drip edge from HD or Lowes. They're about $3 for a 10' stick. I'm an open wheel racing fan - primarily F1 - and have seen a sawtooth pattern cut into the wickerbill to increase its effectiveness. Perhaps triangular notches could be cut into the drip edge to generate additional vorteces. To me, this might be a way to test out the concept before spending big bucks on air tabs.
Take care,
Tom