Pitot Tube Heater Assembly With Isolated Coils for Ice Protection
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Solution Overview
Problem
Pitot tubes in aircraft are prone to ice accumulation, which can lead to operational failures due to ingested ice crystals and moisture, and existing heating elements may not effectively prevent ice formation, especially in extreme conditions.
Innovation Solution
A pitot tube design featuring a separate outer tube and tube sleeve with a heating element isolated from airflow, incorporating heater coils wrapped around the sleeve, water dams, and drain openings to manage ice and moisture, with the sleeve and outer tube fabricated using additive manufacturing and brazing for enhanced protection and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heating elements are placed inside the pitot tube to prevent ice accumulation, then ice prevention capability is improved, but the heating element becomes exposed to moisture and airflow which reduces reliability
Solution Approach 1:
The pitot tube is divided into separate components: an outer tube and an inner tube, with the heating element placed in the annular space between them. This segmentation allows the heating element to be protected from direct exposure to airflow and moisture while still effectively preventing ice accumulation on the pitot tube surface.
Solution Approach 2:
The annular space between the outer tube and inner tube serves as an intermediary chamber that houses the heating element. This intermediate space acts as a protective barrier, shielding the heating element from direct contact with moisture and airflow while allowing heat to be conducted to the pitot tube surface for ice prevention.
2Reliability
If a single integrated pitot tube structure is used, then manufacturing is simpler, but ice protection effectiveness is reduced
Solution Approach 1:
The pitot tube structure is segmented into an outer tube and an inner tube, creating distinct functional zones. The outer tube provides structural integrity and weather protection, while the inner tube contains the tube passage for airflow. This segmentation enables more effective ice protection by allowing independent optimization of each component's function.
3Ease of manufacture
If heating elements are exposed to airflow, then ice prevention is direct and effective, but manufacturing precision requirements increase
Solution Approach 1:
By segmenting the pitot tube into outer and inner tubes with an annular space between them, the heating element can be installed in a protected environment during manufacturing. This segmentation allows for more tolerant manufacturing processes compared to installing heating elements in direct exposure positions, as the annular space provides a buffer zone for positioning adjustments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively prevents ice accumulation, protects the heating element from moisture, and simplifies manufacturing, reducing costs while ensuring consistent and accurate heater coil application, thereby maintaining reliable airspeed measurements.
Implementation Method 1
A heating element is located between the outer tube and the tube sleeve
Implementation Method 2
the tube sleeve is secured to the outer tube via brazing
Data Source
AI summary
A pitot tube includes an outer tube extending from a first tube end to second tube end. The second tube end defines a tip portion of the pitot tube. A tube sleeve is located inside of the outer tube and defines a tube passage extending from the first tube end to the second tube end. A heating element is located between the outer tube and the tube sleeve. The heating element is isolated from airflow into the tube passage. A method of forming a pitot tube includes installing a heating element to an outer surface of a tube sleeve, the tube sleeve defining a tube passage of the pitot tube. The tube sleeve is secured in an outer tube such that the heating element is between the tube sleeve and the outer tube and is isolated from airflow through the tube passage.