Air Data Probe Bulkheads for Moisture Tolerance
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Solution Overview
Problem
Air data probes experience measurement errors and moisture-related issues due to atmospheric moisture accumulation, which becomes increasingly problematic with stricter rain and ice regulations and the use of fly-by-wire flight controls.
Innovation Solution
The air data probe design includes a thermocouple for accurate temperature measurement, offset conduits to prevent particle ingestion, and a bulkhead with capillary tubes and elongated pressure conduits to resist menisci formation and moisture accumulation, enhancing moisture tolerance and reducing pressure sensor errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional air data probe design is used, then manufacturing simplicity is maintained, but moisture accumulation causes measurement errors and pressure spikes
Solution Approach 1:
The probe structure is divided into multiple chambers (first chamber, second chamber, third chamber) separated by bulkheads, with each chamber serving specific functions for moisture management and pressure measurement. This segmentation allows moisture to be contained and managed in specific zones while maintaining accurate pressure measurements in isolated chambers.
Solution Approach 2:
Capillary tubes are introduced as intermediary elements between chambers to control fluid flow and pressure equalization. These capillary tubes act as mediators that allow controlled interaction between chambers while preventing direct moisture ingress into pressure sensing areas, thus improving measurement reliability without requiring complete isolation.
2Measurement precision
If offset conduits are added to prevent particle ingestion, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The conduits are positioned asymmetrically with offsets in both radial and circumferential directions. The first conduit and second conduit are offset from each other, and the third conduit is offset from the first conduit, creating an asymmetric configuration that effectively blocks particle ingress paths while maintaining pressure measurement accuracy. This asymmetric layout prevents particles from following direct axial paths into sensing chambers.
3Reliability
If bulkheads with capillary tubes are installed, then moisture tolerance increases, but manufacturing complexity increases
Solution Approach 1:
The bulkheads integrate multiple functions into single components: they separate chambers, provide mounting surfaces for capillary tubes, and incorporate conduit passages. The capillary tubes are integrated directly into the bulkhead structure, combining moisture management and pressure equalization functions in one assembly step, which reduces the number of separate components and assembly operations required.
Solution Approach 2:
The bulkheads serve multiple purposes simultaneously: they act as chamber separators, provide structural support, incorporate capillary tube openings for moisture management, and contain conduit passages for pressure transmission. This multi-functionality reduces the overall component count and simplifies the assembly process despite the increased functional requirements.
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 solution provides improved accuracy and reduced corrosion, increased moisture tolerance, and enhanced heater control, leading to better aerodynamic performance and reduced maintenance risks by minimizing extreme temperature spikes and moisture-related errors.
Implementation Method 1
a thermocouple having a sense end in the forward tip to measure the temperature in the forward tip
Implementation Method 2
The integrally formed bulkhead includes capillary tubes and elongated pressure conduits to resist menisci formation and moisture accumulation
Data Source
AI summary
An air data probe includes a probe head defining a longitudinal axis between a forward tip and aft base. A port opening is defined in the forward tip. A first conduit is in fluid communication with the port opening to guide fluid flow from the port opening to a first chamber. The first chamber is downstream from the port opening. A second conduit, offset radially and circumferentially from the first conduit, is in fluid communication with the first chamber to guide fluid flow from the first chamber to a second chamber. The second chamber is downstream from the first chamber. The offset between the first and second conduits is configured to prevent particle ingestion from the port opening from entering the second conduit.