Module 5 Supersonic Waves Flashcards
What are the air properties before and after an oblique shockwave?
It is very important on stability of the flight control
Oblique shockwaves are compressive supersonic waves, so the air pressure increases when it passes through an oblique shockwave.
Similar to a normal shockwave
What does B mark in a oblique shockwave?
The angle between the oblique shockwave and the airflow direction before the shockwave. Shock angle
What is deflection angle?
The surface is deflected up at an angle.
What happens if the deflection angle is greater than the maximum deflection angle?
the oblique shockwave will be detached from the leading edge of the deflected corner.
A bow shockwave will from if mach number reaches the detachment number.
What are expansion waves?
A compressible airflow expands when it travels into an increasing volume location or encounters a pressure decreasing disturbance.
Give a an example of a formation of a expansion wave?
Pressure expansion wave will be formed at the entrance of the disturbance, for example: Airflow travels past a surface that is deflected down
What occurs if the air is supersonic flow and the expansion wave cannot propagate with the airflow?
A series of expansion waves at different stages will be formed, this is called a expansion region when a supersonic airflow passes the convex corner.
What are the air properties after a expansion wave?
When supersonic flow is deflected away from the relative airflow the air pressure will decrease and airspeed will increase.
A mach will be formed at the surface which is an expansion wave.
What is the angle between the incoming airflow and the mach wave?
mach angle
There is not heat transfer in the expansion process, what does this mean?
This is a isentropic process (reversible adiabatic process)
incoming mach number is smaller than the outgoing mach number
Energy equation can be used
What is the size of the expansion region dependent on?
greater he deflection angle of the surface, lower the pressure and higher the airspeed or mach number is going to be after the expansion region.
What is the limit of expansion?
When air expands so much that the pressure decreases to 0, then the air speed will reach the highest possible value and the expansion region will be at its limit
What is a isentropic process?
Thermodynamic property of air has not changed.
How does the airflpw change after a oblique shockwave?
It flows in the parallel direction to the deflected surface.
What conditions the size of the expansion region.?
The incoming mach number and the deflected surface.
