Total pressure

The total pressure is referred to as a stagnation pressure, static pressure and total pressure, and describes the condition in a flowing medium. The pressure in a fluid is related to the flow velocity. The total pressure is the pressure that comes when the flow is lossless delayed until almost to a standstill and would. This is often at a stagnation point flow of the case. For compressible and incompressible fluids, different mathematical descriptions for the total pressure result. In connection with liquids ( incompressible ), one speaks frequently on the total pressure and gases ( compressible ) often from the static pressure.

Incompressible case

For an incompressible fluid raises the total pressure as the sum of static and dynamic pressure dar. The static pressure is the pressure that a comoving with the flow observer would feel. The total pressure is calculated as follows:

With:

By the said context can be derived from the measurement of static pressure and total pressure, as can be vergenommen with a Prandtlsonde, determine the flow rate.

For gas flows with low velocities arise only small, negligible changes in density, so that in these cases can also be expected incompressible.

Compressible case

For a compressible fluid, there is a concise relationship between density, pressure and temperature, which leads in conjunction with a flow on the laws of gas dynamics.

Measurement of the total pressure

A reliable means of measuring the total pressure in a flow is the pitot tube.