Question

If the value of Cp=1, then the local pressure can be given as ___________

(a) P = Pfreestream + q

(b) P = 0.5*ρ*V1^2

(c) P = Pfreestream

(d) P = 0

The question was asked in examination.

My enquiry is from Pressure Coefficient in section Inviscid & Incompressible Flow of Aerodynamics

Answer 1

The correct answer is (a) P = Pfreestream + q

To explain: For Cp=1, the flow becomes incompressible and in general Cp tells us how much p differs from Pfreestream in multiples of the dynamic pressure. When Cp=1, it tells that local pressure is one times the dynamic pressure above freestream static pressure.