Aero-engine blade chord length measurement using secant rotation
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Solution Overview
Problem
Existing methods for calculating the profile chord length of aero-engine blades are prone to calculation errors due to complex convex hull structures and close measuring points, which can compromise the aerodynamic performance and safety of the blades.
Innovation Solution
A method and system using secant rotation iteration to determine and calculate the profile chord length of aero-engine blades, where a secant line is rotated or translated to intersect with the pressure surface, and then rotated within the leading and trailing edge point sets to find tangent points and calculate the chord length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the convex hull method is used to calculate chord length, then measurement efficiency is improved, but calculation accuracy deteriorates due to complex structure and close measuring points
Solution Approach 1:
The patent extracts and eliminates the problematic convex hull structure from the measurement process. Instead of using the complex convex hull method that causes calculation errors with close measuring points, the invention directly calculates chord length by identifying extreme points and computing the distance between them, thereby removing the source of calculation errors while maintaining measurement efficiency.
Solution Approach 2:
The patent creates a simplified mathematical model (copy) of the blade profile that captures the essential geometry needed for chord length calculation without requiring the complex convex hull construction. By working with this simplified model defined by extreme points and parametric equations, the system achieves accurate chord length measurement without the computational complexity and errors of the convex hull approach.
2Measurement precision
If direct measurement of chord length is performed, then measurement accuracy can be maintained, but measurement efficiency deteriorates due to difficulty in determining chord line position and tangency
Solution Approach 1:
The patent replaces the manual/mechanical process of determining chord line position and verifying tangency with an automated mathematical calculation system. By using parametric equations to define the blade profile and systematically identifying extreme points through coordinate comparison, the invention automates what would otherwise be complex manual measurement tasks, thereby maintaining accuracy while dramatically improving efficiency.
Solution Approach 2:
The patent transforms the measurement approach by changing from direct physical measurement to mathematical parameter calculation. By representing the blade profile through parametric equations and calculating chord length as a function of identified extreme point coordinates, the system converts a difficult measurement problem into a straightforward computational task that maintains accuracy while improving efficiency.
3Device complexity
If measuring points are deleted to simplify convex hull creation for small radius blades, then device complexity is reduced, but measurement precision deteriorates due to wrong convex hull structure
Solution Approach 1:
The patent extracts and removes the problematic convex hull construction step entirely from the measurement process. By directly identifying extreme points and calculating chord length between them using parametric equations, the invention eliminates the need to create and manage complex convex hull structures, thereby removing the source of errors that occur when measuring points are deleted for small radius blades.
Data Source
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AI summary
The invention discloses a method and system for determining and calculating a profile chord length of an aero-engine blade based on secant rotation iteration, and belongs to the field of profile inspection of the aero-engine blade. The method includes: taking a connection line between two most distant points in a blade profile measuring point set as a secant, and rotating or translating the secant to enable the secant to intersect with a pressure surface so as to obtain a leading edge point set and a trailing edge point set; and rotating the secant in a range of the leading edge point set and the trailing edge point set to obtain tangent points of the secant and leading and trailing edges, and calculating a distance between the two tangent points to obtain chord length. The chord length calculated through the method with high accuracy, the size of a blade can be controlled through the chord length of the blade, and meanwhile, if the chord length is too short, the strength of the blade is reduced, the impact resistance and the aerodynamic performance of the blade are further affected, and thus the aerodynamic performance and safety of the blade can be guaranteed when the chord length of the blade is detected through the method.