Mistuned Gas Turbine Rotor Airfoils for Flutter Resistance
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Solution Overview
Problem
Gas turbine engines experience aerodynamic instability and flutter due to natural vibratory frequencies of airfoils, which are detrimental to their operation, and existing solutions have not effectively addressed this issue.
Innovation Solution
A mistuned rotor design for gas turbine engines is implemented, where airfoils have intentionally varied suction and pressure side surface shapes based on operating states to alter natural vibratory frequencies, reducing susceptibility to flutter and acoustic energy generation. The manufacturing method involves determining specific working and static shapes for airfoils using a processor to create a user interface for precise manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If airfoils have uniform surface shapes, then manufacturing is simpler and consistent, but the rotor is more susceptible to flutter due to natural vibratory frequencies
Solution Approach 1:
The patent applies local quality by varying the surface shape of airfoils in specific regions (suction side and pressure side) while maintaining uniformity in other areas. This localized geometric variation changes the natural vibratory frequencies of individual airfoils, making them less susceptible to flutter, while minimizing the overall complexity of the rotor design.
Solution Approach 2:
The patent introduces asymmetry by creating deliberate differences in the suction side and pressure side surface shapes of airfoils. This asymmetric geometry modification alters the aerodynamic and structural characteristics of each airfoil, thereby changing their natural frequencies and reducing susceptibility to flutter without requiring complete redesign of all airfoil features.
2Stability of the object's composition
If airfoils are mistuned to reduce flutter susceptibility, then rotor stability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes by modifying specific geometric parameters of the airfoil surface (such as curvature, thickness distribution, or camber) within defined ranges. These controlled parameter variations achieve the desired mistuning effect for flutter reduction while establishing clear manufacturing specifications that balance precision requirements with manufacturability.
3Object-generated harmful factors
If airfoil surface shapes are varied to alter natural frequencies, then acoustic energy generation is reduced, but design and analysis complexity increases
Solution Approach 1:
The patent reduces acoustic energy generation by applying local quality modifications to airfoil surfaces in regions that significantly influence noise generation (such as the suction side near the leading edge). This targeted approach effectively mitigates acoustic emissions while limiting the scope of geometric variations, thereby controlling the increase in design and analysis complexity.
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
The mistuned rotor design effectively reduces the susceptibility to flutter and acoustic energy generation by tailoring natural vibratory frequencies, enhancing the operational stability and efficiency of gas turbine engines.
Implementation Method 1
Each airfoil of the plurality of airfoils has a span that extends from 0% at the root to 100% at the tip, a chord that extends from 0% at the leading edge to 100% at the trailing edge and a pressure side opposite a suction side
Implementation Method 2
During the operation of the fans and compressors, due to a natural vibratory frequency of the airfoils, the fans and compressors may experience aerodynamic instability, or flutter
Data Source
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AI summary
A mistuned rotor for a gas turbine engine includes a plurality of airfoils (112, 114) and each airfoil has a span (S) that extends from 0% at a root to 100% at a tip, a chord (CH) that extends from 0% at a leading edge (206) to 100% at a trailing edge (208) and a pressure side opposite a suction side. The pressure side of each airfoil has a pressure side surface shape and the suction side of each airfoil has a suction side surface shape based on an operating state of the rotor. Each airfoil has the same suction side surface shape between 10% and 90% of the chord and between 80% and 100% of the span at a first state. At least one first airfoil has a different suction side surface shape between 10% and 90% of the chord and between 80% and 100% of the span than at least one second airfoil at a static state of the rotor. A method of manufacturing a mistuned rotor includes determining a second working shape and a third working shape for at least one of the suction or pressure side surface that are different from each other.