Replenishable Clearance Tip Probe for Turbine Blade Gap Measurement
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Solution Overview
Problem
Existing non-contact probes for measuring clearance between rotating and stationary components in turbomachinery face challenges such as reliability under elevated temperatures and vibrations, and introduce technical complexities, while contact-based probes require advanced signal handling and may compromise structural integrity.
Innovation Solution
A probe assembly with a replenishable, contacting elongated clearance tip that breaks upon contact with the rotating component, using a tip advancement system to extend a new tip, and a controller to determine clearance based on the tip's length, with options for electrically conductive or piezoelectric materials to sense contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-contact probes are used to measure clearance, then measurement capability is achieved, but device complexity and reliability issues arise under elevated temperatures and vibrations
Solution Approach 1:
The patent replaces complex non-contact measurement systems (radiation-based probes, capacitance probes with advanced signal handling) with a simple mechanical contact-based breakable tip probe. The clearance measurement is achieved through direct mechanical contact where the tip breaks upon touching the rotating blade, eliminating the need for complex signal processing while maintaining measurement capability under harsh conditions
Solution Approach 2:
The patent employs disposable breakable tips that are inexpensive and replaceable. Each tip is designed to break after a single use when it contacts the rotating blade, and new tips are continuously supplied to maintain measurement capability. This approach trades the longevity of expensive non-contact probes for the simplicity and reliability of cheap, replaceable mechanical tips
2Measurement precision
If non-contact probes are used, then clearance measurement is possible, but reliability deteriorates under elevated temperatures and vibrations
Solution Approach 1:
The patent replaces sensitive non-contact measurement systems with a robust mechanical contact system. The breakable tip probe uses simple mechanical principles (contact and fracture) that are inherently more reliable under elevated temperatures and vibrations compared to radiation-based or capacitance-based non-contact probes that require controlled conditions and advanced signal handling
3Strength
If contact-based probes are used, then structural integrity is maintained, but measurement complexity increases
Solution Approach 1:
The patent extracts the complex signal handling and processing components from the measurement system, leaving only the essential mechanical contact element (the breakable tip). The measurement function is simplified to the point where the tip either breaks or doesn't break, providing clear binary feedback without requiring complex signal interpretation circuits or processing algorithms
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
Provides accurate and repeatable clearance measurements without the complexity of non-contact probes, expanding applicability beyond characterization tests and ensuring structural integrity.
Implementation Method 1
an elongated clearance tip extending from the stationary component toward the rotating component... a controller configured to determine a clearance between the stationary component and the rotating component based on a length of the elongated clearance tip extending from the stationary component at a time of contact with the rotating component
Implementation Method 2
the elongated clearance tip includes an electrically conductive material, and the controller detects contact of the elongated clearance tip with the rotating component in response to sensing of an electrical signal communicating through the elongated clearance tip and the rotating component
Implementation Method 3
the elongated clearance tip includes a piezoelectric material, wherein the controller detects contact of the elongated clearance tip with the rotating component in response to sensing of an electrical signal communicating through the elongated clearance tip and the rotating component
Data Source
AI summary
A probe assembly for determining a clearance between a stationary component and a rotating component is provided. A gas turbine system and a related method are also provided. The probe assembly includes an elongated clearance tip extending from the stationary component toward the rotating component. A controller is configured to determine a clearance between the stationary component and the rotating component based on a known length of the elongated clearance tip extending from the stationary component at a time of contact with the rotating component. A tip advancement system is configured to advance a new elongated clearance tip toward the rotating component from the stationary component in response to the elongated clearance tip breaking from the contact with the rotating component.