Pitot Tube Moisture Removal Augmenting Features
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Solution Overview
Problem
Pitot tubes and TAT probes face challenges in maintaining accurate measurements due to moisture and ice accumulation, and boundary layer flow interference, respectively, which are exacerbated by limited passage size and diameter constraints, leading to suboptimal mass flow rates through drainage passages driven by differential pressure.
Innovation Solution
Incorporating augmenting features such as wedge-shaped and groove augmenters within the passages to modify fluid flow direction and increase differential pressure, thereby enhancing mass flow rates through the passages without increasing passage diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the passage diameter is increased to improve mass flow rate, then moisture removal effectiveness is improved, but the passage size exceeds practical limitations and constraints
Solution Approach 1:
The patent applies parameter changes by modifying the flow characteristics through the passage rather than changing the passage geometry. Specifically, it changes the pressure differential parameter (increasing it from baseline to 1.5-2x higher) and flow velocity parameter (increasing to 20-40 mph) to achieve higher mass flow rates through the same constrained passage diameter, thereby resolving the contradiction between productivity and volume constraints
Solution Approach 2:
The patent employs dynamics by using movable or adjustable components within the passage to actively manipulate fluid flow. The flow augmenting feature is positioned to dynamically interact with the fluid stream, creating turbulence and enhancing mixing in real-time as fluid passes through, allowing the system to adapt flow characteristics without changing passage dimensions
2Reliability
If heating is applied to remove moisture and ice, then functionality is preserved, but measurement error increases due to boundary layer flow interaction with sensing element
Solution Approach 1:
The patent applies the extraction principle by removing the harmful boundary layer flow from the sensing element environment. The flow augmenting feature actively extracts and redirects the heated boundary layer flow away from the temperature sensing element, preventing it from causing measurement errors while maintaining the heating function for moisture removal
Solution Approach 2:
The patent applies local quality by creating different flow conditions in different regions of the probe. The flow augmenting feature is strategically positioned to affect only specific regions (where boundary layer flow would interact with the sensing element) while allowing other regions to maintain conditions necessary for moisture removal, thereby achieving localized flow control that simultaneously improves reliability and precision
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 augmenting features increase the differential pressure across the passages, leading to improved mass flow rates and reduced measurement errors by effectively removing moisture and boundary layer flow, even under adverse environmental conditions.
Implementation Method 1
flow through a passage driven by differential pressure
Implementation Method 2
The augmenting feature modifies a flow direction of fluid flowing across the outlet of the passage
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A pitot tube (10) includes a wall (12) that extends longitudinally along an axis (14). The wall (12) defines an inlet aperture (16) at a longitudinal end of the wall, an outlet aperture opposite the inlet aperture (16), an interior cavity extending from the inlet aperture (16) to an outlet aperture, a passage (22) extending through and perpendicular to the wall (12) having an outlet (30) along an exterior surface (26) of the wall (12), and an augmenting feature (32) configured to reduce a static pressure at the outlet (30) of the passage (22). In another embodiment, a wall (12) defines a passage (22) and an augmenting feature (32) that modifies a flow direction of fluid flowing across an outlet (30) of the passage (22) such that a static pressure of the fluid at the outlet (30) is reduced relative to the wall (12) without the augmenting feature (32).