◆ Keep in mind!! Any result derived from Bernoullis equation holds for incompressible flow only
Keep in mind !!!!! Any result derived from Bernoulli’s equation holds for incompressible flow only
3.5 Pressure coefficient o Definition of the pressure coefficient p-p q where 2 q The pressure coefficient is a nondimensional value it can be used throughout aerodynamics, for both compressible fow and incompressible flow
3.5 Pressure coefficient Definition of the pressure coefficient − = q p p Cp where 2 2 1 q = V The pressure coefficient is a nondimensional value, it can be used throughout aerodynamics, for both compressible flow and incompressible flow
o For incompressible flow, the pressure coefficient can be expressed in terms of velocity only If Vo and poo are defined as the freestream velocity and pressure. And v and p are the velocity and pressure at an arbitrary point in the flow Then, with Bernoull's equation Po+opv=p+pr 2 2 or p-p2=p(V2-72)
For incompressible flow, the pressure coefficient can be expressed in terms of velocity only If and are defined as the freestream velocity and pressure. And and are the velocity and pressure at an arbitrary point in the flow. Then, with Bernoulli’s equation, V p V p 2 2 2 1 2 1 p + V = p + V or ( ) 2 1 2 2 p − p = V −V
p-p q 2 2 p-p 2 2 2 p(V-12) p-12 2 O厂 2 Valid for 二 P-P=1 incompressible P flow only
− = q p p Cp ( ) 21 2 2 p − p = V − V 2 2 2 21( ) 21 − = − = V V V q p p Cp or 2 1 = − − = VV q p p Cp Valid for incompressible flow only
=0 C.=1 < C.>0 v>V C.<0 = C.=0 P=p+q。 > p<p
= + = = = = V V p p p p q C V V C V V C V V C V C p p p p p 0 0 0 0 1