Turbine Tip Clearance Measurement Using Shared RF Circuitry
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Solution Overview
Problem
Traditional tip clearance measurement systems require separate circuits and coaxial cables for reference and main frequencies, leading to increased weight, cost, and potential errors due to redundant circuitry, which complicates the measurement of turbine blade tip clearance efficiently.
Innovation Solution
A tip clearance measurement system utilizing a single coaxial cable for both reference and main frequencies, with shared RF circuitry that generates and processes signals, allowing for weight savings and reduced error by using the same waveguide for both frequencies applied at different times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate circuits and coaxial cables are used for reference and main frequencies, then signal processing reliability is improved, but device weight and complexity increase
Solution Approach 1:
The patent combines separate reference frequency and main frequency circuits into a single shared circuit architecture. The same waveguide and signal processing components are used for both frequencies, eliminating redundant circuitry and reducing overall device weight while maintaining signal processing reliability through proper frequency multiplexing and switching mechanisms
Solution Approach 2:
The waveguide and associated circuit components are designed to handle both reference and main frequencies universally. A single coaxial cable and shared circuitry perform multiple functions by processing different frequencies at different time intervals, reducing the number of dedicated components needed for each frequency while preserving measurement accuracy
2Measurement precision
If separate circuits are used for reference and main frequencies, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges separate analysis circuits for reference and main frequencies into a shared circuit structure. By using the same waveguide and signal processing components for both frequencies with proper timing and switching, the system reduces circuit complexity and component count while maintaining the measurement precision required for accurate tip clearance determination
Solution Approach 2:
The system employs periodic switching between reference frequency and main frequency operation. The shared circuitry alternates between processing reference signals and main measurement signals in time-division multiplexed fashion, allowing a single circuit to perform functions previously requiring separate dedicated circuits, thereby reducing complexity while preserving measurement accuracy
3Reliability
If redundant circuitry is used for both frequencies, then signal processing reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines redundant reference and main frequency circuits into a single manufactured assembly. By designing the waveguide and signal processing components to handle both frequencies universally, the system reduces the total component count and assembly complexity, directly lowering manufacturing costs while maintaining measurement reliability through proper frequency management and switching protocols
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 approach enables accurate measurement of turbine blade tip clearance with significant weight savings and reduced operational costs by eliminating the need for redundant circuitry and cables, while minimizing measurement errors.
Implementation Method 1
the probe directs electromagnetic (EM) waves toward the turbine blade. In addition, the probe monitors the reflection of the EM waves (as they reflect off the turbine blades) and uses the monitored reflections to determine the distance between the blade tips and the stationary case
Data Source
Figure 1
Figure 2
AI summary
A tip clearance measurement system (TCMS) includes a probe (16) and sensing circuitry (18). The probe (16) directs microwave signals toward a turbine blade (12) and receives microwave signals reflected by the turbine blade (12). The sensing circuitry (18) includes a switch having a first state in which a main frequency is provided at an output of the switch and a second state in which a reference frequency is provided at an output of the switch. The sensing circuitry (18) further includes a first conditioning circuit that receives a frequency provided at the output of the switch and provides a conditioned frequency to the probe (16) and a second conditioning circuit that receives both the conditioned frequency provided by the first conditioning circuit and a reflected frequency received by the probe (16), and provides a conditioned output based on the conditioned frequency and reflected frequency.