Question

a diamond airfoil is placed in a supersonic flow at a positive angle of attack. an expansion fan forms below the diamond airfoil at the leading edge and an oblique shock forms above the diamond airfoil at the leading edge. then:

Answer 1

In a supersonic flow, a diamond airfoil at a positive angle of attack forms an expansion fan below it and an oblique shock above it.

Step-by-step explanation:

In this scenario, a diamond airfoil is placed in a supersonic flow at a positive angle of attack. This leads to the formation of an expansion fan below the diamond airfoil at the leading edge, and an oblique shock forms above the diamond airfoil at the leading edge.

Expansion fans occur when a fluid (in this case, air) is accelerated and its speed exceeds the local speed of sound. The expansion fan allows for smooth compression of the air, reducing its speed and increasing its pressure. On the other hand, oblique shocks are formed when a supersonic flow encounters an obstacle at an angle. These shocks result in a sudden decrease in velocity and an increase in pressure.

So, in summary, placing a diamond airfoil at a positive angle of attack in a supersonic flow leads to the formation of an expansion fan below and an oblique shock above the airfoil's leading edge.