3.4 Pitot tube: measurement of airspeed o Definition of static pressure, the measurement of the static pressure Static pressure A measured here Static pressure orifice
3.4 Pitot tube: measurement of airspeed Definition of static pressure, the measurement of the static pressure
Definition of stagnation pressure, the measurement of the stagnation pressure essure gage C Total pressure measured here V=0 B 0 Pitot tube
Definition of stagnation pressure, the measurement of the stagnation pressure
The usage of Pitot tube The pressure at point C is the stagnation pressure po The speed at point C is equal to zero The pressure at point A is the static pressure p, The speed at point A is equal to free stream velocity K The speed and pressure and at point a and B are the same apply Bernoulli's equation, we have PA+apVA=PB+pV
The usage of Pitot tube. The pressure at point C is the stagnation pressure 0 p The pressure at point A is the static pressure 1 p The speed at point C is equal to zero The speed at point A is equal to free stream velocity V1 The speed and pressure and at point A and B are the same, apply Bernoulli’s equation, we have 2 2 2 1 2 1 pA + VA = pB + VB
O厂 p1+p12=p+0 2(p0-p1) o Combined instrument for the measurement of both static and total(stagnation) pressure Static pressure Total pressure felt here felt here
0 2 1 0 2 p1 + V1 = p + or 2( ) 0 1 1 p p V − = Combined instrument for the measurement of both static and total(stagnation) pressure
o Definition of dynamic pressure, the relationship between of the static pressure, total pressure and ddynamic pressure 2 q=- For incompressible flows 2 2 po static dynamic total pressure pressure pressure
Definition of dynamic pressure, the relationship between of the static pressure,total pressure and dynamic pressure. 2 2 1 q = V For incompressible flows 0 2 1 1 2 1 p + V = p static pressure dynamic pressure total pressure