Integral Epoxy Cap Probe for Gas Turbine Tip Clearance
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Solution Overview
Problem
Traditional capacitance-based fan blade tip clearance (BTC) probes alter the engine structure, reducing gas turbine engine efficiency by disrupting the air seal and requiring modifications that compromise performance.
Innovation Solution
A fully integral epoxy cap probe is designed with a body, frame, and sensor elements made from specific materials, including hydrophobic and conductive resins, which are integrated into the fan case to monitor tip clearance without altering the engine structure, using a monolithic structure and soft leads to maintain aerodynamic integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional cap probes are installed to monitor tip clearance, then measurement capability is provided, but engine efficiency is reduced due to structural alterations
Solution Approach 1:
The probe structure is merged with the outer air seal structure, where the probe body forms an integral part of the air seal assembly. This integration eliminates the need for separate structural modifications while maintaining both the measurement capability and the aerodynamic sealing function, thereby resolving the contradiction between measurement precision and energy loss.
Solution Approach 2:
The probe structure serves multiple functions simultaneously: it provides tip clearance measurement capability while also maintaining the outer air seal integrity. The integrated design allows the same structure to fulfill both measurement and sealing roles, preventing the energy loss that would result from separate structural modifications.
2Ease of manufacture
If traditional cap probes alter engine structure to accommodate sensors, then sensor installation is enabled, but aerodynamic integrity is compromised
Solution Approach 1:
The sensor housing and air seal structure are merged into a single integrated component. This eliminates the need for separate structural alterations while providing adequate space for sensor installation and maintaining aerodynamic integrity, as the integrated structure is designed to preserve the original airflow paths and sealing surfaces.
3Ease of manufacture
If structural modifications are made for probe installation, then probe mounting is achieved, but component life is reduced due to increased thermal loads
Solution Approach 1:
The probe mounting structure is integrated with the existing air seal components rather than requiring separate structural modifications. This integration ensures that the mounting process does not create additional stress concentration points or alter thermal pathways, thereby preserving the original component life while achieving probe installation.
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 allows for precise monitoring of tip clearance without reducing engine efficiency, maintaining aerodynamic performance and extending component life by minimizing thermal loads and structural alterations.
Implementation Method 1
a capacitance-based BTC probe (cap probe) may be placed in the outer air seal to monitor this gap
Implementation Method 2
the second material comprises at least one of a hydrophobic dielectric resin, epoxy, and/or thermoset material
Data Source
AI summary
A fully integral epoxy cap probe may comprise a body having a cavity disposed radially outward of a fan blade and comprising a first material, a frame disposed within the cavity and comprising a second material, a first sensor element and a ground plane disposed within the frame, the first sensor element and the ground plane comprising a third material, and a first soft lead in electronic communication with the first sensor element and the ground plane.