Virtual Probe Blade Tip Timing Analysis
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Solution Overview
Problem
Current blade tip timing analysis techniques are inadequate for extracting blade tip amplitudes for engine orders with cycles that are integer multiples of the shroud segment angle, leading to high condition numbers and large uncertainties in displacement calculations in gas turbine engines.
Innovation Solution
A method involving the use of virtual probes to adjust probe angles and engine orders, allowing for the calculation of blade tip displacement amplitudes by iteratively optimizing the condition number, enabling analysis of blade tip timing data spaced at integer multiples of a base angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If timing probes are positioned at integer multiples of the shroud segment angle, then the probe placement is feasible under stress and thermal factors, but high condition numbers result leading to large uncertainty in blade tip displacement calculations
Solution Approach 1:
The patent creates a virtual probe that copies the function of a physical probe but with optimized angular positioning. The virtual probe is calculated using the measured data from existing probes, allowing the system to achieve precise measurements without physically relocating probes under stress and thermal constraints.
Solution Approach 2:
The patent changes the angular position parameter of the virtual probe to a non-integer multiple of the base angle, optimizing it to reduce the condition number. This parameter optimization enables precise blade tip displacement calculations while maintaining the physical constraint of having probes only at integer multiples of the shroud segment angle.
2Device complexity
If current blade tip timing analysis techniques are used with probes at integer multiples of base angle, then the system is simple to implement, but it cannot accurately extract blade tip amplitudes for engine orders with cycles that are integer multiples of the base angle
Solution Approach 1:
The virtual probe creates a virtual measurement point that enables accurate extraction of blade tip amplitudes for problematic engine orders. This copying approach adds minimal computational complexity while dramatically improving measurement capability for specific engine order cases.
Solution Approach 2:
The virtual probe acts as an intermediary that bridges the gap between the limited physical probe positions and the requirement for accurate measurements at all engine orders. It mediates the measurement process by providing the necessary angular diversity without requiring physical probe relocation.
3Measurement precision
If virtual probe angle is optimized to reduce condition number, then uncertainty in displacement calculations is reduced, but additional computational iterations are required
Solution Approach 1:
The patent performs partial optimization by iterating through a reasonable range of virtual probe angles (e.g., 0 to 360 degrees) rather than exhaustively searching all possible configurations. This partial action achieves sufficient condition number reduction to improve measurement precision while avoiding excessive computational time.
Solution Approach 2:
The optimization process changes the virtual probe angle parameter systematically through iterations, stopping when a satisfactory condition number is achieved or when the maximum iteration limit is reached. This parameter optimization balances precision improvement with computational efficiency.
Data Source
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AI summary
A method of analysing blade tip timing data obtained from an array (Pk) of stationary timing probes (3) that are spaced at integer multiples of a base angle. Replace one of the probes (3) with a virtual probe (Pv) to give a virtual probe set (42). Set an initial probe angle (θv) and an initial engine order (EOv) for the virtual probe (Pv). Calculate the condition number (CN) for the virtual probe set (42). If the condition number (CN) at least meets a threshold criterion, solve the virtual probe set (42) for blade tip displacement amplitude. Else increment the virtual probe angle (θv) and/or the virtual engine order and iterate from calculating the condition number. Else reinstate the replaced probe (3) and replace a different probe (3) from the array of probes (Pk) with the virtual probe (Pv); then iterate from setting the initial virtual probe angle and engine order.