Stagnation pressure

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Total Pressure redirects here. Total pressure may also refer to a sum of partial pressures.

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 pressure a fluid retains when brought to rest isentropically from mach number M.

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

or, assuming an isentropic process, the stagnation pressure can be calculated from the ratio of stagnation temperature to static temperature:

\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

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).

Stagnation quantities (e.g. stagnation temperature, stagnation pressure) are frequently used in jet engine performance calculations.

Pitot tubes are used to measure stagnation (or total) pressure. A combined pitot/static tube is used on aircraft to determine flight speed..

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