Air flow Flashcards
What does the term laminar flow mean
air flows smoothly in a streamlined manner
What does the term turbulent flow mean
Air molecules travel in random motion which is superimposed on the overall flow direction
What does the term flow separation mean
separated air flow which is not moving in the direction of general air flow
Where on the CL v Angle of attack graph does it show where air separation begins
Where graph has stop being linear an tapers off
What is Cl limited by during take-off and landing
Stall
How does an increase in camber effect Cl
Cl increases
What causes shockwaves
Before getting to the wing, air is undisturbed. However when it hits the wing there are abrupt changes in it’s speed, temperature and pressure which lead to shockwaves
What causes a sonic boom
Due to a sudden change in pressure. “vapour cone” is due to change in temperature as air condenses slightly, you can see it clearly
What is the speed of sound in m/s
340m/s
Calculating Mach number
airspeed/speed of sound
What type of flow is it when M
Subsonic flow:
air flow behaves normally
What Mach number region is subsonic flow
M
What type of flow is it when 0.7
Transonic flow:
Compressibility becomes important, same locally supersonic flow
Bernoulli’s equation breaks down
What Mach number region is transonic flow
0.7
What type of flow is it when M > 5
Hypersonic flow:
Heat becomes a massive issue!
Only relevant to rockets
