At which flow regime does aerodynamic quantities such as coefficient of pressure, lift become independent of Mach number?

Subsonic

Hypersonic

Transonic

Supersonic

Correct Answer : Hypersonic

Explanation : For flows above Mach number 5 i.e. hypersonic flow, it is seen that the aerodynamic quantities such as coefficient of pressure, coefficient of life and wave drag become independent of the Mach number. This aspect was even described by Newton while formulating his Newtonian theory which states the coefficient of pressure is independent of Mach number at hypersonic speed.

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Why is hypersonic similarity parameter essential?

Hypersonic flow over cone

Supersonic flow over wedges

Hypersonic flow over slender bodies

Hypersonic flow over flat plate

Correct Answer : Option (C) : Hypersonic flow over slender bodies

Explanation : Hypersonic similarity parameter K is an important governing parameter in order to study the hypersonic flow i.e. flow with Mach number greater than 5 over slender bodies. It is given by the product of free stream Mach number and flow deflection angle.

For two bodies with same shape but different scales, which of these parameters must be equal for the flow to be same in hypersonic regime?

Mach number

Normal flow velocity

Tangential flow velocity

Product of Mach number and slenderness ratio

Correct Answer : Option (D) : Product of Mach number and slenderness ratio

Explaination : The product of Mach number and slenderness ratio along with gamma are the two parameters which appear in the non – dimensional equations. For a body that has same shape but have different scale ratio, if these parameters are same, the flow over them at hypersonic regime remain same. This is the physical meaning of the hypersonic similarity parameter.