Blade Wear Measurement Using Rotating Cam and Positioning System
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Solution Overview
Problem
Existing methods for measuring blade wear in turbomachines do not allow for repetitive measurements due to variability in the insertion point of the measuring device between blades, and require disassembly of the turbomachine for accurate assessment.
Innovation Solution
A device with a rotating shaft and elliptical cam is used to measure blade wear by inserting the cam between adjacent blades, featuring a positioning system that maintains constant alignment, allowing for repetitive and systematic wear assessment without disassembly, using a torquemeter to measure the twisting torque required to space out the blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring device with an end cam is used to measure blade wear by inserting it between adjacent blades, then blade wear can be measured, but the insertion point of the cam cannot be kept constant between measurements
Solution Approach 1:
A positioning device is introduced as an intermediary element between the measuring device and the blades. This positioning device includes a positioning element that engages with a reference feature on the turbine housing or blade assembly, ensuring that the measuring device is consistently positioned at the same location for each measurement. The positioning element acts as a mediator that translates the general insertion action into a precise, repeatable position.
Solution Approach 2:
The invention replaces manual positioning methods with a mechanical positioning system that uses geometric constraints and reference features. Instead of relying on operator skill to insert the cam at the same location each time, the mechanical positioning system automatically ensures consistent placement through physically defined reference surfaces and engagement features that guide the measuring device to the correct position.
2Measurement precision
If traditional measuring methods are used for blade wear assessment, then wear measurement is possible, but the turbomachine must be disassembled
Solution Approach 1:
The measuring device is extracted from the need for disassembly by designing it to access the blades through the existing gap between adjacent blades in the rotating assembly. The end cam is inserted laterally between blades that are already positioned close together during normal operation, allowing measurement without removing blades from the rotor or disassembling the turbine housing.
Solution Approach 2:
Instead of accessing the blades from the end of the rotor (which would require disassembly), the measurement is performed by accessing the blades from the radial direction between adjacent blades. This inverted approach to measurement access allows the measuring device to engage the blades in their installed position, eliminating the need for disassembly while maintaining measurement capability.
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
Enables repetitive and comparable measurements of blade wear across multiple pairs of blades without disassembling the turbomachine, providing accurate wear assessment through consistent positioning and torque measurement, facilitating the determination of blade replacement or reuse based on torque values.
Implementation Method 1
the elastic deformation obtained for a certain twisting torque applied to the cam provides a blade wear rate
Data Source
Figure 1~1a
Figure 2
Figure 3
AI summary
A method and device for measuring the wear of blades (8) of a turbomachine (1), each blade (8) comprising a respective sector (17) connected to its free end, according to which a cam (24) is introduced between a pair of adjacent blades (8) of the turbomachine (1) and blocked, by means of positioning devices (28, 29), in a certain position and with a certain orientation with respect to the pair of blades (8); the cam (24) being thus rotated, by applying a twisting torque, so as to reciprocally space out the two blades (8) by elastic deformation; and the twisting torque applied to obtain the elastic deformation providing a wear rate of the blades (8).