What is the shape of the pressure curve on the upper surface of a circular arc airfoil at zero angle of attack?

Pressure first increases instantly and then decreases linearly in a straight line

Pressure increases and becomes constant till the trailing edge of the airfoil

Pressure increases and becomes constant, and then becomes negative instantly

Pressure decrease follows a parabolic path and then becomes atmospheric pressure again

Correct Answer : Pressure first increases instantly and then decreases linearly in a straight line

Explanation : According to shock expansion theory, shock wave interactions determine the aerodynamic loads on the surface of the airfoil. Detached shock is formed on the blunt edge which increases the pressure and then it is linearly decreased along the upper length of the airfoil.

Recently Updated in Aerodynamics Questions

If there is a supersonic flow over a blunt edge, then the detached shock is observed. Where is the oblique shock observed in the detached shock?

On the blunt edge point

Far away from the edge

Just above the blunt edge point

Near the trailing edge of the section

Correct Answer : Option (C) : Just above the blunt edge point

Explanation : In a detached shock, the normal shock is observed on the blunt edge and then slowly loses strength and becomes an oblique shock just above the edge point. Finally the detached shock becomes a Mach line far away from the edge.

What is true about the flow properties above and below the discontinuity?

The pressure on both sides are different

The pressure on both sides are equal

The flow direction of both sides are different

The density and temperature are the same on both the sides

Correct Answer : Option (B) : The pressure on both sides are equal

Explanation : On either side of the discontinuity the flow direction needs to be same. The pressure is also same on both sides as the flow is not turning.

What is the shape of the pressure curve on the upper surface of a thin diamond wedge airfoil at zero angle of attack?

Pressure increases and becomes constant

Pressure decrease follows a parabolic path

Pressure decreases linearly in a straight line

Pressure increases instantly and becomes constant, and then suddenly becomes negative and becomes constant

Correct Answer : Option (D) : Pressure increases instantly and becomes constant, and then suddenly becomes negative and becomes constant

Explanation : According to shock expansion theory, shock wave interactions determine the aerodynamic loads on the surface of the airfoil. Oblique shock and expansion waves decrease and increase the pressure respectively.