《空气动力学》（双语版）Chapter 3 Fundamentals of Inviscid, incompressible Flow

For incompressible flow 22 o Applications of venturi tube 1吃>V V2<Ⅵ P2<p P2>p Convergent duct Divergent duct

For incompressible flow A1 V1 = A2 V2 Applications of venturi tube

Throat V 2 2 Pressure is a minimum at the throat

o Measurements of flow speed in a duct From Bernouli's equation V12=-(2-p1)+V2 From continuity equation we have A 2 Then 2 2 2 (P2-P1)+ 2

Measurements of flow speed in a duct. 2 2 1 2 2 1 ( ) 2 V = p − p +V  From Bernoulli’s equation From continuity equation, we have 1 2 1 2 V A A V = Then 2 1 2 2 1 2 1 2 1 ( ) 2 V A A V p p         = − + 

2(P2-p1) Vp4/1)2-1

( ) 1 2( ) 2 1 2 2 1 1 − − = A A p p V 

Airplane model A Test section Settling I Nozzle Diffuser cham ber (reservoir (a) Open-circuit tunnel Mote Nozzle Diffuser Test section Settling V1 cham ber reservoIr p. A b)Closed-circuit tunnel