Laser Thermography for Wind Turbine Rotor Blade Testing
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Solution Overview
Problem
Current methods for testing rotor blades of wind power installations are time-consuming and costly, especially for those located on the open sea, as they require the wind power installations to be stopped and cannot be performed during operation due to the need for thermography methods that cannot handle moving components.
Innovation Solution
A method involving the transmission of an aiming laser beam to detect reflection on the rotor blade, followed by a higher power measurement laser beam to heat and measure temperature changes at multiple points, allowing for quick and efficient testing without stopping the installation, using a test apparatus with an aiming light source, detection apparatus, measurement laser, and temperature measurement tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermography method is used to test rotor blade, then structural faults can be detected, but the wind power installation must be stopped and the method cannot be used during operation
Solution Approach 1:
The patent replaces traditional contact-based thermography heating methods with a laser-based heating system. The laser beam can be transmitted through optical fibers to heat the rotor blade surface remotely, enabling non-contact heating that works during rotation. This substitution allows the testing to proceed without stopping the wind power installation while maintaining fault detection capability.
Solution Approach 2:
The patent introduces an intermediary system consisting of optical fibers and laser transmission apparatus that mediates between the heat source and the rotating rotor blade. This intermediary allows energy transfer without direct mechanical contact, enabling the heating process to occur during blade rotation and eliminating the need to stop the installation for testing.
2Reliability
If rotor blade is accessed for testing, then structural faults can be checked, but the process becomes time-consuming and costly
Solution Approach 1:
The patent replaces manual inspection procedures with an automated laser-based thermography system. The laser heating combined with infrared camera monitoring creates a rapid, automated testing process that eliminates time-consuming manual access and inspection, significantly reducing testing duration while maintaining detection accuracy.
Solution Approach 2:
The patent enables continuous testing during rotor blade operation rather than requiring separate shutdown periods for inspection. The laser heating and temperature monitoring can proceed continuously as the blade rotates, eliminating idle time and making the testing process as efficient as the operational process itself.
3Productivity
If high power laser beam is used to heat rotor blade during rotation, then testing can be performed during operation, but safety risks increase due to moving components
Solution Approach 1:
The patent uses optical fibers as intermediaries to transmit laser energy to the rotating blade. This indirect transmission method allows precise control of laser delivery and enables quick disconnection or redirection if safety issues arise, reducing the harmful effects of high-power lasers while maintaining operational testing capability.
Solution Approach 2:
The patent incorporates feedback mechanisms where the reflected aiming light is detected and used to control the measurement laser beam. This feedback loop ensures precise targeting and allows real-time adjustment of laser power and positioning, enhancing safety during rotational operation by preventing unintended heating or damage.
4Measurement precision
If aiming light beam power density is increased to improve detection accuracy, then impact point can be precisely identified, but damage risk to rotor blade increases
Solution Approach 1:
The patent uses a low-power aiming laser beam transmitted before the measurement laser beam to precisely identify and mark the impact point on the rotor blade. This preliminary action allows the subsequent high-power measurement laser to be accurately positioned without repeatedly exposing the blade to high power, reducing cumulative damage risk while maintaining detection precision.
Solution Approach 2:
The patent applies different power densities to different stages of the testing process: a low power density for the aiming beam to prevent damage, and a higher power density for the measurement beam at the precisely identified impact point. This localized quality approach ensures measurement precision where needed while minimizing harmful effects overall.
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 rapid and accurate testing of rotor blades during operation, reducing maintenance costs and time, while ensuring safety and comprehensive coverage of the rotor blade surface, even in challenging environments like the open sea.
Implementation Method 1
detection of any reflection of the aiming light beam on an impact point on the rotor blade by a detection apparatus
Implementation Method 2
electrically controlled transmission of a measurement laser beam with a measurement laser beam power density which is greater than the aiming light beam power density, onto the impact point, such that the rotor blade is heated at the impact point
Implementation Method 3
measurement of a temperature change at the impact point
Data Source
AI summary
The invention relates to a method for testing a rotor blade (13.1) of a wind power plant (1), which sweeps across a rotor blade surface to be covered during operation of the wind power plant, comprising the following steps: emitting a target light beam (20), in particular a target light beam having a power density, in a direction of the target light beam onto the rotor blade surface to be covered; detecting a possible reflection of the target light beam by a detection device at a point of incidence (16) on the rotor blade; electrically controlled emission of a measurement laser beam (21) which has a power density that is larger than the power density of the target light beam immediately after detection of the reflection at the point of incidence so that the rotor blade is heated at the point of incidence; measuring a temperature distribution at the point of incidence; and repeating the steps (a) to (d) for several points of incidence.