Capacitance Probe Cooling Channels for High-Temperature Clearance Sensing

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Solution Overview

Problem

Current capacitance probes are limited to operating at temperatures below 2270°F due to thermal insulation around the center conductor, which prevents effective heat transfer and increases the risk of debris deposition, leading to electrical performance degradation.

Innovation Solution

A cooling system is implemented within the capacitance probe center conductor, comprising channels that allow cooling air to directly contact and cool the center conductor, bypassing thermal insulation, thereby maintaining effective thermal management and reducing debris accumulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal insulation is provided around the center conductor, then electrical performance is maintained, but heat transfer from the center conductor to the probe housing is prevented, causing the center conductor temperature to approach gas path temperature

Engineering Contradiction:

Improveelectrical performanceVSAvoidcenter conductor temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The probe is divided into thermally isolated segments: the center conductor is electrically and thermally separated from the probe housing through insulation rings, allowing independent temperature management. This segmentation enables the housing to be cooled while the center conductor operates at higher temperatures necessary for electrical performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the probe are given different thermal properties: the probe housing has high thermal conductivity for heat dissipation, while the center conductor and its immediate surroundings have thermal insulation properties. This local differentiation allows each component to operate at its optimal temperature range.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the center conductor is exposed to high temperature gas path, then measurement capability is maintained, but debris deposition on the center conductor face increases, causing electrical performance degradation

Engineering Contradiction:

Improvemeasurement capabilityVSAvoiddebris deposition

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

Cooling air is supplied to the center conductor face before debris can accumulate and cause electrical degradation. The cooling channels are designed to deliver cool air directly to the conductor surface, preemptively preventing thermal and contaminant buildup that would otherwise occur during operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Cool air rushes through the cooling channels and across the center conductor face at high velocity, quickly removing heat and preventing debris adhesion. The rapid airflow skips over potential contamination zones, reducing residence time for debris deposition.

Inventive Principle:

Principle #21Skipping (Rushing through)

3Temperature

If cooling channels are added to cool the center conductor, then temperature control is improved, but probe complexity increases

Engineering Contradiction:

Improvecenter conductor temperature controlVSAvoidprobe structure

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The cooling channels are merged with the existing probe structure, integrating the cooling function into the housing and center conductor design. The channels utilize the same structural components, eliminating the need for separate cooling systems and reducing overall complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The probe housing serves multiple functions: it provides structural support, electrical insulation, and now thermal management through integrated cooling channels. The center conductor also serves dual purposes as both the electrical measurement element and a component with internal cooling pathways, reducing the need for additional dedicated cooling parts.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 cooling system enables capacitance probes to operate at higher temperatures without increasing size or impacting performance, reducing debris-related electrical degradation and enhancing thermal efficiency.

Implementation Method 1

a cooling system is implemented within the capacitance probe center conductor, comprising channels that allow cooling air to directly contact and cool the center conductor

Methodology Applied

Scientific EffectForced Convection: Forced Convection

Data Source

PatentUS20250372284A1Cooling for capacitance probe center conductor

Publication Date: 2025.12.04 RTX CORP

AI summary

A capacitance probe for measuring clearances within a gas turbine engine includes a center conductor having a face that is exposed to a high temperature source of the gas turbine engine, a connection line connected to the center conductor. A probe housing surrounds the center conductor, the connection line and the connection circuitry. The probe housing defines an opening for exposing the face of the center conductor to the high temperature source of the gas turbine engine. The probe housing and the center conductor define at least one cooling channel that passes through the center conductor to provide cooling air from a cool air source to the high temperature source to provide cooling to the face of the center conductor.