Aerodynamically shaped static pressure sensing probe

• US 20050000280A1
• Filed: 07/01/2003
• Published: 01/06/2005
• Est. Priority Date: 07/01/2003
• Status: Active Grant

• Current Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Original Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Inventors: Moynihan, Patrick J., Foster, Roger D., Heine, Paul F., Owens, David G.
• Granted Patent: US 6,915,687 B2
• Time in Patent Office: Days
• US Class Current: 73/170.20
• CPC Class Codes: B64D 43/02 for indicating aircraft speed or stalling conditions
• CPC Class Codes: G01P 13/025 indicating air data, i.e. flight variables of an aircraft, e.g. angle of attack, side slip, shear, yaw
• CPC Class Codes: G01P 5/165 Arrangements or constructions of Pitot tubes

Abstract

A static pressure sensing probe has an aerodynamically shaped cross section, and extends laterally from an aircraft surface sufficiently so that an outer end of the probe is a short distance outside the boundary layer on the aircraft surface on which the probe is mounted. The probe has surface corrugations or ridges along the probe, and the ridges include an upstream ridge adjacent the leading edge, and a downstream ridge spaced rearwardly from the upstream ridge. The ridges cause pressure disturbances along the probe surfaces. Static pressure sensing ports are positioned on the surfaces of the probe relative to the ridges in regions of pressure disturbances caused by the ridges. The probes can be mounted on opposite sides of the aircraft and pneumatically or electrically connected to average the pressures from selected sets of ports.

Claims

1. A static pressure sensing probe for use with an aircraft, the probe having an aerodynamically shaped cross section and a length protruding from a probe base, the aerodynamically shaped cross section extending substantially the entire length of the probe, the probe length being sufficient so the probe aerodynamically shaped cross section extends beyond a boundary layer of air when the probe is mounted on a surface of an aircraft, at least one surface corrugation on the probe extending along the probe axial length outwardly of the boundary layer from the probe base, and a first pressure sensing port on the probe.

2. The probe of claim 1 wherein the surface corrugation is an upstream corrugation relative to air flowing over the probe, a second downstream surface corrugation on the probe formed substantially parallel to the upstream surface corrugation, a second pressure sensing port on the probe, the first and second pressure sensing ports being positioned adjacent to the upstream and second downstream corrugations at locations to provide a selected static pressure function at each of the pressure sensing ports.

3. The probe of claim 1, wherein said corrugation comprises a ridge raised upwardly from a generally aerodynamically shaped upper surface of the probe.

4. The probe of claim 3 wherein the at least one surface corrugation and the first pressure sensing port are on a top surface of the probe, and further comprising a second bottom corrugation on a bottom surface of the probe, extending along the probe axial length outwardly from the boundary layer from the probe base, and a second pressure sensing port on the bottom surface of the probe.

5. The probe of claim 4 further comprising the second pressure sensing port positioned at a location wherein the sensed static pressure at the second pressure sensing port is at a desired relationship to static pressure sensed at the first pressure sensing port.

6. The probe of claim 5, wherein the second pressure sensing port is positioned at a location wherein static pressures sensed at the first and second pressure sensing ports are substantially equal at a known orientation of the probe relative to airflow across the probe.

7. The probe of claim 5, wherein the probe comprises top and bottom spaced walls having the top and bottom surfaces, the spaced walls forming a pressure chamber, and the first and second ports both opening to the pressure chamber.

8. The probe of claim 2, wherein the corrugations cause a normalized pressure function (P_m−

P)/q_c to change at different locations in a direction on the probe substantially parallel to the direction of air flow over the probe, and wherein P_m is measured pressure, P is local static pressure, and q_c is total pitot pressure minus true static pressure.

22. The static pressure sensing probe of claim 1 wherein the first pressure sensing port is in a selected position adjacent to the at least one surface corrugation.

9. A static pressure sensing probe having a base, an outer end, a leading edge facing in the direction of an air flow, and a trailing edge, the probe cross section perpendicular to a length of the probe between the base and the outer end defining upper and lower surfaces that have convex aerodynamically contoured surface portions adjacent the respective leading and trailing edges, at least a first ridge on at least one surface of the probe extending along the length of the probe, said ridge having sufficient height from the adjacent portions of the one surface to cause a static pressure disturbance of air flowing across the one surface, wherein the local static pressure rises and falls as it flows over the first ridge, a pressure sensing port on the probe positioned adjacent to the first ridge and at a position that is selected to have a different static pressure from the pressures at the convex surface portions.

10. The probe of claim 9, and wherein there is a second ridge on the one surface spaced toward the trailing edge of the probe from the first ridge, and causing a second static pressure disturbance, and a second pressure sensing port on the probe positioned adjacent to the second ridge at a selected position to sense pressure in a region of the second static pressure disturbance.

11. The probe of claim 10, wherein the first ridge and the second ridge are both on the upper surface of the probe.

12. The probe of claim 9, wherein the first ridge is spaced from the leading edge of the probe, and one convex surface portion extending between the first ridge and the leading edge.

13. The probe of claim 10, wherein said aerodynamically shaped cross section has vertically spaced top and bottom surfaces, and the upper and lower surfaces having the convex surface portions tapering toward each other in a downstream direction from the first and second ridges, each of the upper and lower surfaces having first and second ridges and first and second pressure sensing ports.

14. The probe of claim 13 wherein the probe has at least first and second chambers therein, the first pressure sensing ports in both the upper and lower surfaces opening to the first chamber, and the second pressure sensing ports in both the upper and lower surfaces opening to the second chamber.

15. The probe of claim 9, wherein the length of the probe positions the outer end outside of and adjacent to the boundary layer of an aircraft on which the probe is mounted.

16. The probe of claim 9, wherein the length of the probe is maintained to be not substantially greater than 10 cm.

17. A method of forming a family of static pressure sensing probes, with each probe having a base, an outer end, and a length extending between the base and the outer end, and having a generally aerodynamically shaped cross section, at least one corrugation extending along the length of the probe at a location to cause a pressure disturbance comprising rising and falling static pressures as air flows over the corrugation, the method comprising determining a selected air speed of an aircraft on which the probe is to be mounted, and determining an outward extent of a boundary layer of air on a surface of an aircraft at the location where the base of the probe is to be mounted, providing a probe length that positions the outer end a outside of but adjacent to the outward extent of the boundary layer, determining the pressure pattern of air flow across the corrugation at the selected air speed, positioning at least one pressure sensing port at a desired location relative to the corrugation where a sensed pressure function is at a desired level, and with the desired location outwardly from the base sufficient to be to the exterior of the outward extent of boundary layer air on the surface of the aircraft on which a probe is to be mounted.

18. The method of claim 17, including providing the family of probes as a separate probe for each of a selected number of different aircraft.

19. The method of claim 17, including providing at least two corrugations on the probe, one being downstream of the other sufficiently far so that a pressure disturbance caused by the upstream corrugation does not substantially affect a pressure disturbance at the downstream corrugation, determining the pressure pattern across both of the corrugations, and selecting a pressure level for positioning at least two ports in the probe, one port adjacent each of the at least two corrugations.

20. A static pressure sensing probe for use with an aircraft, the probe having a leading edge and a trailing edge and having convex upper and lower surfaces between the leading and trailing edges to form an aerodynamically shaped cross section, and the probe having an axial length protruding outwardly from a probe base which is mountable on an aircraft surface, the probe axial length being sufficient so the probe aerodynamically shaped cross section extends outwardly beyond a boundary layer of air when the probe is mounted on a surface of an aircraft, at least one surface corrugation on at least one probe surface, the at least one surface corrugation extending along the probe axial length outwardly of the boundary layer from the probe base, and a pressure sensing port on the at least one probe surface.

21. The static pressure sensing probe of claim 20 wherein the pressure sensing port is in a selected position adjacent to the at least one surface corrugation.