godlameroso wrote: ↑07 Feb 2022, 15:59
More air over the diffuser increases mass flow, since that part creates upwash, the pressure is higher than the diffuser. More mass and more upwash = greater pressure difference between diffuser and upper surface.
Flow doesn't move from low to high pressure. So you are missing out a few factors there.
Never said it does. Force is transmitted from the high pressure side to the low side. The top part of the diffuser is the high side, the inner part of the diffuser is the low side. Since there is less pressure, the high pressure side on top will create a force in the low pressure direction. Take your hands and put them together, if you press your right side towards your left side, if the pressure is equal you won't move, if your left hand has less pressure it gives way to the right. That's what's happening with the diffuser. The part above has higher pressure than the part below, the part below gives way.
If you move air in a direction where its pressure rises, where it slows down(like a parachute), the air's kinetic energy becomes converted to pressure energy. The faster the air is moving, the greater the collision, the faster you clap your hands, the louder the sound. You want clean fast air to collide with the pressure increasing surfaces to impart greater kinetic force. The pressure increasing surfaces are going to slow down that air anyway, and those surfaces are going to generate pressure difference between the top of the car and the bottom of the car.
Faster travelling air imparts more kinetic energy, but to satisfy Bernoulli's principle, the faster the fluid, the lower its static pressure, as this compensates for the increase in kinetic energy...until it doesn't(choked flow/pressure increase(like smacking into a barn/or the diffuser in a turbine inlet)).
