Turbine Blade Defect Detection Using Phased Array Ultrasonic Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting defects in turbine blades, such as cracks, are ineffective when the blades are installed on a rotor, as they require dismantling or cannot access the complex geometry of the inner hub area, leading to unreliable and time-consuming testing.
Innovation Solution
A method using a phased-array ultrasonic test with a fixing device made of deformable material to attach a probe to the turbine blade surface, allowing for precise emission and reception of ultrasonic pulses, comparison with reference signals, and evaluation of echo signals to detect defects without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ultrasonic testing is performed on turbine blades in the installed state, then productivity and reliability are improved, but the complexity of accessing the inner hub area and dealing with complex geometry increases
Solution Approach 1:
The probe is integrated into the hub structure, with the piezoelectric element nested within a housing that is itself integrated into the wheel disc hub. This nested arrangement allows the testing device to be embedded within the component being tested, enabling direct access to the inner hub area without external manipulation or disassembly.
Solution Approach 2:
A coupling agent is introduced as an intermediary substance between the probe's acoustic lens and the turbine blade surface. This mediator enables effective ultrasonic transmission across the interface, overcoming the geometric complexity and accessibility issues by creating a reliable acoustic coupling path through the complex geometry.
2Measurement precision
If the probe is integrated into the hub, then measurement precision is improved, but the ease of manufacture decreases
Solution Approach 1:
The integrated probe assembly is manufactured as a separate modular unit and then installed in the hub. This segmentation allows the probe to be manufactured and calibrated independently with high precision, while the hub can be manufactured separately. The modular approach simplifies the overall manufacturing process compared to creating a fully integrated monolithic structure.
Solution Approach 2:
The piezoelectric element is electrically connected to the evaluation device through electrical contacts that pass through the hub structure. By changing the electrical connection parameters and using through-hub wiring, the probe can be precisely positioned and electrically connected without requiring complex integrated circuitry within the hub itself, thus improving manufacturability while maintaining measurement precision.
3Reliability
If ultrasonic testing is performed on the inner hub area, then reliability is improved, but the difficulty of detecting and measuring increases due to geometry-related reflectors
Solution Approach 1:
The evaluation device continuously monitors the ultrasonic echo signals and compares them against reference values. This continuous evaluation process allows for real-time distinction between geometry-related reflectors and actual defects by analyzing signal patterns over time, thereby improving reliability while managing the complexity of signal interpretation through automated continuous assessment.
Solution Approach 2:
Reference ultrasonic echo signals are pre-determined for the specific hub geometry before actual testing. These reference signals, which capture the expected reflections from geometric features without defects, are stored and used for comparison during testing. This preliminary action simplifies defect detection by providing a baseline for comparison, reducing the difficulty of interpreting signals in the presence of geometry-related reflectors.
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 reliable, fast, and reproducible detection of defects in turbine blades in the installed state, reducing costly dismantling and allowing for early detection and monitoring of fatigue or vibration cracks.
Implementation Method 1
an ultrasonic pulse signal is emitted and an echo signal caused by reflections on defects or shape boundaries is received
Implementation Method 2
which has a piezoelectric element as a transducer for non-contact testing
Data Source
AI summary
The invention relates to a method and a measuring and evaluation device for determining defects in a turbine blade and to a fixing device for fixing a probe to a turbine blade surface.