What should be the shape of the nozzle to achieve supersonic speed?

Divergent

Convergent

Convergent-Divergent

Divergent-Convergent

Correct Answer : Convergent-Divergent

Explanation : In order to achieve supersonic speed from rest we use a convergent divergent nozzle. This is because in the convergent section the flow is subsonic and is accelerated with decreasing cross-sectional area of the nozzle. The flow reaches sonic speed at the throat after which it is further accelerated in the divergent section as the supersonic flow increases with the increasing cross-sectional area of the nozzle.

Recently Updated in Aerodynamics Questions

Which of these laws is used to find the heat flux at a point in the fluid?

Fourier law

Fick�s law

Kepler�s law

Newton�s law

Correct Answer : Option (A) : Fourier law

Explanation : Fourier law which is also known as the law of heat conduction is used to find out the heat flux at any point in the fluid. It is given by the formula:

Where, heat flux is in the y – direction
Minus sign indicates that the heat flows from high temperature to low temperature and thus q?_y is in opposite direction to the temperature gradient.

What happens to the shear stress if the thickness between the two plates is increased in a Couette flow?

Increases

Decreases

Remains same

Becomes infinite

Correct Answer : Option (B) : Decreases

Which of these laws is obeyed by a Newtonian fluid?

Prandtl law

Newtonian law

Shear stress law

Incompressible fluid law

Correct Answer : Option (C) : Shear stress law

Explanation : Newtonian fluids are characterized by those fluids that obey the shear stress law. Aeronautics domain makes use of newtonian fluids only (air, other gases). Those fluids that don’t obey shear stress law are known as non – newtonian fluids (blood).