TAT Probe Frontal Area Reduction for Deicing
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Solution Overview
Problem
Conventional Total Air Temperature (TAT) probes face issues in icing conditions due to accretion of water droplets and ice crystals, leading to congestion and erroneous readings, and suffer from boundary layer separation at low mass flows causing turbulence and uncorrectable temperature errors.
Innovation Solution
A TAT probe design with a reduced frontal projected area, featuring an airflow inlet with a first surface parallel to the airflow and a second inclined surface to facilitate pressure gradient and boundary bleed, along with a perpendicular sensor flow passage and corner bleed vents to minimize particle impact and heat control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If conventional TAT probes use an air bump with significant projected area for inertial filtering and boundary layer control, then particle separation performance is improved, but particle impact and surface liquid accumulation increase leading to degraded performance in precipitation environments
Solution Approach 1:
The patent changes the geometric parameters of the probe, specifically reducing the projected area of the air bump and modifying the inlet geometry. This parameter change maintains the inertial filtering capability while reducing the surface area exposed to particle impacts, thereby decreasing liquid accumulation and improving performance in precipitation environments.
Solution Approach 2:
The patent reorients the sensor flow passage to be perpendicular to the mounting surface, changing the dimensional arrangement of components. This spatial reconfiguration allows the sensing element to be positioned where it is less exposed to particle impacts while still receiving adequately filtered airflow, thus resolving the contradiction between filtering performance and particle exposure.
2Reliability
If TAT probes incorporate heating elements for anti-icing performance, then ice formation is prevented, but boundary layer heating creates extraneous heat sources leading to DHE (Deicing Heater Error) and uncorrectable temperature errors
Solution Approach 1:
The patent applies heating elements selectively to specific regions of the probe housing rather than uniformly across all surfaces. By concentrating heating only where ice accretion is most likely to occur (on the external housing), the design prevents ice formation while minimizing heating of the internal boundary layer that would otherwise create measurement errors.
Solution Approach 2:
The patent segments the heating function by separating external housing heating (for anti-icing) from internal boundary layer control. This segmentation allows independent optimization of each function: robust heating for ice prevention on the outside, while maintaining thermal isolation and minimal heating inside the sensing region to preserve measurement accuracy.
3Measurement precision
If TAT probes use internal thermal isolation of the temperature element to minimize DHE, then measurement accuracy is improved, but internal accretion may form and grow on the isolated element leading to rapid blockage and erroneous measurements
Solution Approach 1:
The patent introduces a heated boundary layer as an intermediary protective mechanism. By maintaining a warm layer of air between the external environment and the internally isolated temperature element, this intermediary layer prevents ice and water droplets from reaching and blocking the sensing element, thus protecting it while preserving its thermal isolation and measurement accuracy.
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
Improves deicing performance by reducing erroneous temperature measurements and maintaining accurate air temperature readings in icing conditions by minimizing particle accretion and heat-related errors.
Implementation Method 1
the second surface may be inclined relative to the first surface to help facilitate a desirable pressure gradient and boundary bleed passage function
Implementation Method 2
the second surface may be inclined relative to the first surface to help facilitate a desirable pressure gradient and boundary bleed passage function
Implementation Method 3
The air bump aids inertial filtering and also provides a means of boundary layer bleed control
Implementation Method 4
Flow separation creates two problems for the accurate measurement of TAT. The first has to do with turbulence and the creation of irrecoverable losses
Implementation Method 5
Anti-icing performance is facilitated by heater elements embedded in the housing walls
Implementation Method 6
The internal temperature element is typically thermally isolated from the main heated probe so that DHE is minimized
Data Source
AI summary
Deicing performance of a total air temperature (TAT) probe may be improved by reducing the size of a frontal projected area upstream of an inertial bend of the TAT probe. In accordance with various embodiments, a TAT probe may comprise an airflow inlet having a first surface substantially parallel to an incoming airflow, a primary airflow passage through the TAT probe from the airflow inlet to a primary airflow outlet, and a total air temperature sensor assembly disposed within a sensor flow passage. In various embodiments, the sensor flow passage may be oriented perpendicular to a mounting surface of the TAT probe. Further, the first surface may be perpendicular to the sensor flow passage. In various embodiments, the airflow inlet may have a second surface that is inclined relative to the first surface to help facilitate a desirable pressure gradient and boundary bleed passage function.