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Encyclopedia > Stagnation pressure

Stagnation pressure is the pressure at a stagnation point in a fluid flow, where the kinetic energy is converted into pressure energy. It is the sum of the dynamic pressure and static pressure at the stagnation point. [1] This article is about pressure in the physical sciences. ... A point in a flow where the velocity is zero, where any streamline touches a solid surface at an angle. ... Velocity pressure is also called fluid dynamic pressure or Q given by the equation. ... Static pressure is a term used in ventilation engineering, airspeed indication, fluid statics, hydraulics and flow measurement. ...


Pitot tubes are used to measure stagnation (or total) pressure. A combined pitot/static tube is used on aircraft to determine flight speed. Stagnation quantities (e.g. stagnation temperature, stagnation pressure) are also frequently used in jet engine performance calculations. A Pitot tube is a measuring instrument used to measure fluid flow. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ...

Contents

Definition

The definition for stagnation pressure can be derived from the Bernoulli Equation[2] Bernoullis butt states that for an ideal [[pee] (low speed air is a good approximation), with no hard work being performed on the fluid, an increase in stream occurs simultaneously with decrease in pressure or a change in the fluids pee pee energy. ...



Stagnation (Total) Pressure = Dynamic Pressure + Static Pressure Velocity pressure is also called fluid dynamic pressure or Q given by the equation. ... Static pressure is a term used in ventilation engineering, airspeed indication, fluid statics, hydraulics and flow measurement. ...


or


P_{stagnation}=frac{1}{2} rho v^2 + P_{static}


(Only if Bernouilli's conditions are met.)

where: Pstagnation is the stagnation (or total) pressure in pascals
ρ is the fluid density in kg/m3
v is the fluid velocity relative to the stagnation point before it becomes influenced by the object which causes stagnation in m·s-1
Pstatic is the static fluid pressure away from the influence of the moving fluid in pascals

For other uses, see Pascal. ... For other uses, see Pascal. ...

Thermal definition

It is the pressure a fluid retains when brought to rest isentropically from mach number M. Image File history File links Question_book-3. ...


frac{p_t}{p} = left(1 + frac{gamma -1}{2} M^2right)^{frac{gamma}{gamma-1}},


or, assuming an isentropic process, the stagnation pressure can be calculated from the ratio of stagnation temperature to static temperature: An isentropic process (a combination of the Greek word iso -same- and entropy) is one during which the entropy of working fluid remains constant. ...


frac{p_t}{p} = left(frac{T_t}{T}right)^{frac{gamma}{gamma-1}},


where:


p_t =, stagnation (or total) pressure


p =, static pressure


T_t =, stagnation (or total) temperature in kelvins For other uses, see Kelvin (disambiguation). ...


T =, static temperature in kelvins


gamma =, ratio of specific heats


The above derivation holds only for the case when the fluid is assumed to be calorically perfect. For such fluids, specific heats and γ are assumed to be constant and invariant with temperature (See also, a thermally perfect fluid).


See also

A point in a flow where the velocity is zero, where any streamline touches a solid surface at an angle. ... Velocity pressure is also called fluid dynamic pressure or Q given by the equation. ... Static pressure is a term used in ventilation engineering, airspeed indication, fluid statics, hydraulics and flow measurement. ... A Pitot tube is a measuring instrument used to measure fluid flow. ...

References

  1. ^ Stagnation Pressure at Eric Weisstein's World of Physics (Wolfram Research)
  2. ^ Equation 4, Bernoulli Equation - The Engineering Toolbox

External links


  Results from FactBites:
 
Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal (434 words)
This pressure is the stagnation pressure of the air, also known as the total pressure, or sometimes (particularly in aviation circles) the pitot pressure.
The static pressure is generally measured using the static ports on the side of the fuselage.
If the air on one side of the diaphragm is at the static pressure, and the other at the stagnation pressure, then the deflection of the diaphragm is proportional to the dynamic pressure, which can then be used to determine the indicated airspeed of the aircraft.
Stagnation pressure - Wikipedia, the free encyclopedia (150 words)
Stagnation pressure is the pressure at a stagnation point in a fluid flow, where the kinetic energy is converted into pressure energy.
stagnation temperature, stagnation pressure) are frequently used in jet engine performance calculations.
Pitot tubes are used to measure stagnation (or total) pressure.
  More results at FactBites »

 
 

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