Wind Turbine Rotor Blade Pressure Spectrum Analysis for Flow Stall Detection
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Solution Overview
Problem
Wind turbines experience OAM noise due to critical flows causing flow stalls, which are difficult to detect and manage, especially when angle of attack exceeds a certain value, leading to increased low-frequency noise radiation over long distances.
Innovation Solution
A method to evaluate the flow on a rotor blade by recording a pressure spectrum, determining characteristic values, forming an indicator value from their relationship, and assessing for critical flows to adjust the rotor blade angle and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the angle of attack is increased to improve power generation, then power output is improved, but flow stall occurs causing OAM noise and reduced reliability
Solution Approach 1:
The patent applies preliminary action by detecting critical flow conditions before flow stall occurs. The pressure spectrum analysis and indicator value evaluation identify impending flow separation, allowing the control system to adjust the angle of attack in advance to prevent flow stall and OAM noise generation, thus maintaining both power output and flow stability
Solution Approach 2:
The patent implements feedback through continuous monitoring of pressure spectra on the rotor blade surface and evaluation of indicator values that characterize flow conditions. This feedback loop enables real-time detection of critical flow states and triggers control actions to adjust the angle of attack, preventing flow stall while maintaining optimal power generation
2Measurement precision
If pressure measurement is used to detect flow conditions, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent applies the taking out principle by extracting only the essential information from the pressure spectrum - specifically the indicator value that characterizes flow conditions. Rather than processing the entire complex pressure spectrum, the method extracts the relevant frequency range and calculates a simplified indicator value, reducing measurement system complexity while maintaining flow detection accuracy
Solution Approach 2:
The patent replaces complex mechanical flow measurement systems with acoustic pressure spectrum analysis. By using pressure sensors to measure acoustic signals and analyzing the frequency spectrum, the system achieves accurate flow detection without complex mechanical instrumentation, simplifying the overall measurement system
3Power
If flow stall is allowed to occur naturally, then power generation is maximized, but low-frequency noise radiation increases over long distances
Solution Approach 1:
The patent applies preliminary anti-action by taking measures to prevent flow stall before it occurs. The pressure spectrum analysis detects critical flow conditions in advance, and the control system adjusts the angle of attack to prevent flow separation. This preliminary intervention avoids the generation of intense low-frequency noise associated with flow stall while maintaining near-optimal power generation
4Object-generated harmful factors
If throttled operation is used to reduce OAM noise, then noise modulation is reduced, but power output decreases
Solution Approach 1:
The patent applies preliminary action by detecting critical flow conditions before OAM noise generation begins. By identifying impending flow stall through pressure spectrum analysis and adjusting the angle of attack in advance, the system prevents noise modulation without requiring throttled operation, thus maintaining both low noise levels and optimal power output
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 method allows for early detection and reduction of critical flows, thereby minimizing low-frequency noise modulation and improving flow conditions, reducing noise radiation and operational interference.
Implementation Method 1
Recording at least a part of a pressure spectrum of a pressure, in particular wall pressure, on the rotor blade at at least one measuring position
Data Source
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AI summary
The invention relates to a method for evaluating an inflow on a rotor blade (108) of a wind turbine (100), having the following steps: - detecting at least one part of a pressure spectrum of a pressure (P), in particular wall pressure, on the rotor blade (108) at at least one measuring position, - determining at least two characteristic values (P1, P2) from the pressure spectrum, - forming an indicator value (I) from a relationship of the at least two characteristic values (P1, P2) to each other, and - evaluating whether a critical inflow (24) is present on the basis of the indicator value (I).