Total pressure probe

A method of sensing total pressure using a probe which has an alignment portion having a first passageway disposed in the alignment portion about a longitudinal axis of symmetry, a sensor portion spaced from the alignment portion leaving a plenum therebetween in fluid communication with the first passageway, and a bleed portion wherein the bleed portion is in fluid communication with the plenum and the working medium flow path, comprising the steps of:

• diverting a portion of the flow from the working medium flow path to the passageway of the alignment portion;
• converting substantially all of the total pressure of the diverted flow to a static pressure and to velocity pressure at the inlet to the alignment passageway wherein the velocity pressure results from flow along streamlines parallel to the alignment passageway;
• converting a portion of the static pressure of the diverted flow to velocity pressure wherein the velocity pressure results from flow along streamlines parallel to the longitudinal axis of the alignment passageway;
• converting substantially all of the velocity pressure of the working medium fluid leaving the alignment passageway and entering the plenum to static pressure at the entrance to the sensor portion;
• converting the static pressure of the working medium fluid into velocity pressure in the bleed portion of the probe such that the static pressure of the free stream is equal to the static pressure in the bleed portion of the probe at the point of communication between the bleed portion and the working medium flow path to duct the working medium gases from the plenum into the working medium flow path.

A pressure probe in fluid communication with a region outside of the probe for sensing the total pressure of working medium fluid in a flow path for working medium gases which comprises:

• means for diverting a portion of the flow from the working medium flow path to the pressure probe which includes
• means for ducting the diverted portion of the flow in a first direction;
• and
• means for converting the total pressure of the flow into static pressure and into velocity pressure wherein the velocity pressure results from flow along streamlines parallel to the first direction;
• means for detecting static pressure;
• means for converting substantially all of the velocity pressure of the diverted flow to static pressure at a region adjacent to the means for detecting static pressure;
• and
• means for ducting all of the diverted flow away from the probe into the region outside of the pressure probe.

A pressure probe for sensing total pressure in a flow path for working medium gases, the probe having working medium gases passing through the probe which comprises:

• an alignment portion which includes
• a first passageway in fluid communication with the working medium flow path, the first passageway having a longitudinal axis, and
• a wall bounding the passageway, the wall forming an inlet which converges in the downstream direction such that the absolute value of the slope of the wall at a first point in the inlet with respect to the longitudinal axis of the passageway is greater than the absolute value of the slope of the wall in the inlet at a second point downstream of the first point;
• a sensor portion spaced axially from the alignment portion leaving a plenum therebetween, the sensor portion having a second passageway which is oriented in axial alignment with the first passageway and which is in fluid communication with the plenum;
• wherein the probe has at least one third passageway having an inlet in fluid communication with said plenum and an outlet which adapts the third passageway to be in fluid communication with a region outside of the probe to establish a difference in static pressure under operative conditions between the inlet to the alignment portion and the outlet of the third passageway such that the portion of the working medium gases which enters the alignment portion is discharged from the third passageway.