Downstream-facing air sensor for icing condensation
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Solution Overview
Problem
Current air sensors fail to reliably measure total air temperature and humidity in icing conditions due to contamination from ice and water droplets, and existing designs struggle to separate these particles from the airflow effectively, leading to inaccurate readings.
Innovation Solution
A flared-end air sensor design with a thin rim and downstream-facing inlet, which minimizes the accumulation of water and ice by promoting shedding and reducing entrainment, ensuring a particulate-free airflow for accurate sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional air sensor design with upstream-facing inlet is used, then the sensor can sample air flow, but ice and water droplets are ingested into the sensor causing measurement contamination
Solution Approach 1:
The inlet of the air sensor is inverted to face downstream instead of upstream. This reversal prevents ice and water droplets from being drawn into the sensor while still allowing air sampling, thereby eliminating measurement contamination without sacrificing sampling capability
Solution Approach 2:
The downstream-facing inlet configuration converts the harmful effect of particle ingestion into a beneficial separation mechanism. The flow dynamics that would normally carry particles into the sensor now cause particles to be shed away from the inlet, while clean air is still sampled effectively
2Reliability
If heating is applied to avoid anti-icing, then ice accretion is prevented, but the heat contaminates the TAT measurements and humidity measurements
Solution Approach 1:
The harmful heating element is removed from the system. Instead of using heat to prevent ice accretion, the downstream-facing inlet design passively prevents particle ingestion through flow dynamics, eliminating the source of measurement contamination while maintaining anti-icing protection
Solution Approach 2:
The sensor design uses the natural flow dynamics of the air stream itself to prevent particle ingestion. The downstream-facing inlet leverages the existing flow field to shed particles away from the inlet, requiring no additional energy input or active control systems
3Strength
If the inlet opening has a thick rim, then structural strength is improved, but water and ice accumulate on the inlet causing particle ingestion
Solution Approach 1:
By reversing the inlet orientation to face downstream, the design changes the flow interaction with the rim. Instead of the rim acting as a trap for accumulating water and ice, the downstream flow causes particles to be shed away from the inlet area, eliminating accumulation regardless of rim thickness
Solution Approach 2:
The solution moves from addressing particle accumulation in the radial dimension (rim thickness) to addressing it in the axial dimension (inlet orientation). By changing the inlet direction along the flow axis, particle shedding occurs naturally without requiring changes to rim geometry
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 the ingestion of ice and water droplets, providing accurate measurements of temperature, humidity, and other air properties across a wide range of conditions, including mixed phase icing environments.
Implementation Method 1
The opening is provided at a flared end of the body that provides an enlargement of a cross-sectional area occupied by the air sensor, and has a peripheral edge with an average thickness of 5 mm or less
Data Source
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AI summary
An air flow sensor is provided with an opening facing downstream and having a thin downstream facing edge to prevent condensation or buildup of moisture thereon. The sensor has been found to reduce entrainment of particles in a mixed phase stream. The sensor is suitable for mounting to an aircraft, and to determining air temperature and relative humidity.