High Speed Aerodynamics Flashcards
what speed is considered subsonic flow?
this is speeds below mach 0.75
what speeds are considered transonic?
these are speeds between Mcrit and M1.3
what speed becomes supersonic?
these are speeds above M1.3
What happens to all the variables in a normal subsonic shockwave?
static pressure - increases velocity - decreases temperature - increases total pressur e- decreases density - increases
what is MCrit
the speed at which at least one portion of the upper surface reaches mach 1
what happens to shockwaves as you start to increase mach number?
- shockwave moves rearwards
- second shockwave is formed under wing
- both move rearwards until mach 1 where they are both at the back
- M1.05 bow wave forms ahead of wing
- at mach 1.3 the shockwave attaches to the wing
what happens to the shockwave angle as you increase mach number?
the shockwave angle becomes more acute the faster that you fly.
what happens to the variables in an oblique shockwave?
pressure - increases
velocity - decreases
total pressure - decreases
what happens to Total pressure and velocity in a shockwave?
they both decrease
what happens in shockwave compression?
temp -increases
total pressure - decreases
density - increases
velocity - decreases
what is high speed buffet?
separated airflow from the shockwaves hits the tailplane and acts like turbulence.
what happens in shockwave expansion?
temp -decreases
total pressure - increases
density - decreases
velocity - increases
what’s the equation for mach shockwave angle?
1/mach no
affect of angle of attack on mcrit?
with increase in angle of attack the mcrit value will decrease.
what is a shock stall and why does it occur?
loss of lift due to airflow seperation when flying faster than MCRIT
