Quote:
Originally Posted by Cycle
I was under the assumption that according to the Bernoulli equation, the stagnation point is where the forward motion of the vehicle has caused the air to come to rest (or even reverse direction and create eddies), and therefore stagnation pressure is highest at that point where the air is stopped.
https://en.wikipedia.org/wiki/Stagnation_point
"On a streamlined body fully immersed in a potential flow, there are two stagnation points—one near the leading edge and one near the trailing edge."
The stagnation point at the rear of a vehicle is otherwise known as the wake. It causes wake drag... does it not cause the same effect (in this case, pressure drag) at the front of the vehicle?
Here's a research paper that discusses frontal pressure drag:
http://www.ara.bme.hu/oktatas/letolt...cleaerodyn.pdf
If we removed that high pressure stagnation point and transferred it to the rear of the vehicle, would it not act to reduce forebody pressure drag (and coincidentally wake drag), especially if we're heating and expanding that air before we put it out back of the vehicle?
Here's a good discussion of it:
Does putting an opening on the front of a vehicle nose increase drag? - Aerodynamic engineering - Eng-Tips |
As long as the vehicle has a front,it will have a stagnation point(s).It's not the issue.
Pressure drag is the differential between the front and the back.
Streamlining eliminates the wake which renders the highest possible base pressure,eliminating pressure drag altogether,leaving only skin friction drag and drag associated with the sloughing boundary layer.