Air Data Probe Asymmetric Inlet for Moisture Resistance

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Solution Overview

Problem

Conventional air data probes experience measurement errors due to moisture accumulation, which forms menisci at pressure ports, affecting the accuracy of airspeed and altitude calculations.

Innovation Solution

The air data probe features a wall tap port inlet with an elongated, non-circular perimeter that opens at an angle, preventing a full meniscus from forming and reducing moisture-induced pressure errors, achieved through specific shapes like teardrop, racetrack, or elliptical designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional circular wall tap port inlet is used, then the device structure is simple and easy to manufacture, but moisture accumulates and forms menisci that cause pressure measurement errors

Engineering Contradiction:
Improvepressure measurement accuracyVSAvoidinlet perimeter shape complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies asymmetry by changing the inlet perimeter from a symmetric circular shape to an asymmetric elongated shape with different dimensions in perpendicular directions. This asymmetric geometry prevents the formation of complete menisci that would otherwise form in circular ports, thereby eliminating moisture-induced pressure errors while maintaining manufacturing feasibility through standard machining operations.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If the wall tap port inlet is modified with an elongated perimeter, then meniscus formation is prevented and pressure accuracy improves, but the inlet design becomes more complex

Engineering Contradiction:
Improvemoisture resistanceVSAvoidinlet fabrication difficulty
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by modifying the geometric parameters of the inlet perimeter from a circular configuration (equal dimensions in all directions) to an elongated configuration (different dimensions in perpendicular directions). Specifically, the inlet has a first dimension in a first direction and a second dimension in a second perpendicular direction, where these dimensions are different, creating an elongated shape that prevents meniscus formation while remaining manufacturable through conventional processes.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If moisture accumulates in the pressure ports, then the probe can be used in various atmospheric conditions, but measurement errors occur due to meniscus formation

Engineering Contradiction:
Improveoperational environment rangeVSAvoidairspeed and altitude accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies the 'blessing in disguise' principle by converting the harmful effect of moisture accumulation into a beneficial outcome. Instead of preventing moisture accumulation (which would require complex heating or drying systems), the elongated inlet geometry is designed to work with moisture presence, preventing complete meniscus formation and ensuring that even when moisture is present, accurate pressure measurements are maintained. This allows the probe to operate reliably in moist environments without sacrificing measurement precision.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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

This design maintains pressure accuracy in dry conditions and improves performance in moist environments by minimizing meniscus formation and pressure errors compared to traditional circular inlets.

Implementation Method 1

The wall tap port inlet has an elongated inlet perimeter... configured to prevent a full meniscus from forming or only permits a weak meniscus to be formed over the port

Methodology Applied
Scientific EffectMeniscus formation: Capillary Action

Data Source

PatentEP2700952B1Moisture resistant air data probes
Publication Date: 2016.04.20 ROSEMOUNT AEROSPACE INC
  • EP2700952B1 patent drawingFigure 1~2
  • EP2700952B1 patent drawingFigure 3~8
  • EP2700952B1 patent drawingFigure 9~13

AI summary

An air data probe includes a probe head (102). The probe head defines a longitudinal axis (A-A) with a forward tip (101) and aft base (103) and includes a wall tap port inlet (106) defined in the probe head aft between the forward tip and the aft base. The wall tap port inlet (106) opens on an angle relative to the longitudinal axis, wherein the wall tap port inlet has an elongated inlet perimeter configured to resist the formation of a meniscus, or otherwise reduce moisture induced pressure errors.