FOREIGN PRIORITY

This application claims priority to India Patent Application No. 201911002095, filed Jan. 17, 2019, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.

BACKGROUND

Exemplary embodiments pertain to the art of aircraft sensors such as pitot tubes, and more particularly to aerodynamic performance and ice protection of pitot tubes.

A pitot tube is widely used to determine airspeed of an aircraft or other vehicle, or to measure air or gas velocities in industrial applications. In particular, by measuring stagnation pressure of a fluid driven into the pitot tube, together with a measured static pressure, the airspeed of the aircraft can be determined. In certain flight conditions, the pitot tube may be subject to ice accumulation from moisture in the air. For this reason, pitot tubes are equipped with heating elements to prevent such ice accumulation. Further, in other conditions, the pitot tube may ingest ice crystals which then accumulate inside of the pitot tube and cause failure in its operation. A typical pitot tube is substantially cylindrical with an internal diameter containing the heating elements, or coils to prevent ice accumulation.

From wind tunnel experiment it is found that by increasing the pitot tube length and modifying the outside profile of the pitot tube tip, aerodynamic performance of the pitot tube can be improved. Such modifications can, however, have a negative effect on ice accumulation prevention in the pitot tube.

BRIEF DESCRIPTION

In one embodiment, a pitot tube includes an outer tube extending from a first tube end to second tube end, the second tube end defining a tip portion of the pitot tube, the tip portion including an inlet opening. A tube sleeve inside of the outer tube at least partially defines a tube passage extending from the first tube end to the second tube end. The tube sleeve includes a sleeve outer surface having a sleeve body portion having a first outer diameter and a sleeve tip portion located at the tip portion of the pitot tube. The sleeve tip portion has a second outer diameter smaller than the first outer diameter. A heating element is located between the outer tube and the tube sleeve at at least the sleeve tip portion.

Additionally or alternatively, in this or other embodiments the heating element is located at both of the sleeve tip portion and the sleeve body portion.

Additionally or alternatively, in this or other embodiments the heating element is one or more heater coils wrapped around the tube sleeve.

Additionally or alternatively, in this or other embodiments the tube sleeve includes one or more sleeve grooves in the sleeve outer surface to accommodate the heater coils.

Additionally or alternatively, in this or other embodiments the tube passage includes a passage throat portion extending from the inlet opening, and a passage body portion extending from the passage throat portion opposite the inlet opening. The throat portion has a smaller throat opening diameter than a body opening diameter of the passage body portion.

Additionally or alternatively, in this or other embodiments the tip portion of the pitot tube converges from an inlet opening diameter at the inlet opening toward the passage throat portion.

Additionally or alternatively, in this or other embodiments the throat opening diameter is less than the inlet opening diameter.

Additionally or alternatively, in this or other embodiments one or more water dams extend from the tube sleeve into the tube passage.

Additionally or alternatively, in this or other embodiments one or more drain openings extend from the tube passage through the tube sleeve and through the outer tube.

Additionally or alternatively, in this or other embodiments the tube sleeve is secured to the outer tube via one of brazing or laser metal deposition.

In another embodiment, a method of forming a pitot tube includes forming a tube sleeve, the tube sleeve defining a tube passage and including a sleeve outer surface having a sleeve body portion having a first outer diameter, and a sleeve tip portion located at a tip portion of the pitot tube. The sleeve tip portion has a second outer diameter smaller than the first outer diameter. The tube passage includes a throat portion extending from a first end of the tube sleeve, and a body portion extending from the throat portion to a second end of the tube sleeve. The throat portion has a smaller throat opening diameter than a body opening diameter of the body portion. A heating element is installed at at least the sleeve tip portion of the tube sleeve. The tube sleeve is secured in an outer tube such that the heating element is between the tube sleeve and the outer tube.

Additionally or alternatively, in this or other embodiments installing the heating element to the tube sleeve includes forming one or more sleeve grooves in the outer surface of the tube sleeve, and installing the heating element in the one or more grooves.

Additionally or alternatively, in this or other embodiments the heating element is a heater coil.

Additionally or alternatively, in this or other embodiments the heating element is installed at both the sleeve tip portion and the sleeve body portion.

Additionally or alternatively, in this or other embodiments the tube passage includes a passage throat portion extending from an inlet opening, and a passage body portion extending from the passage throat portion opposite the inlet opening, the throat portion having a smaller throat opening diameter than a body opening diameter of the passage body portion.

Additionally or alternatively, in this or other embodiments a converging portion is formed in the outer tube from an inlet opening diameter at the inlet opening toward the passage throat portion.

Additionally or alternatively, in this or other embodiments the throat opening diameter is less than the inlet opening diameter.

Additionally or alternatively, in this or other embodiments one or more water dams extend from the tube sleeve into the tube passage.

Additionally or alternatively, in this or other embodiments one or more drain openings extend from the tube passage through the tube sleeve and through the outer tube.

Additionally or alternatively, in this or other embodiments the tube sleeve is secured to the outer tube via one of brazing or laser metal deposition.

