Rotor Blade Cutback Distribution for Gas Turbine Noise Reduction
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Solution Overview
Problem
Current methods for controlling fan noise in gas turbine engines are complex, costly, and increase engine weight, and existing noise reduction techniques, such as trailing edge blowing, involve drilling holes which may not be efficient.
Innovation Solution
A gas turbine engine rotor design featuring a subset of blades with cutbacks at the leading or trailing edges, which alters the shockwave distribution to achieve symmetrical flow and reduce noise, while maintaining engine efficiency and minimizing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If forward swept blade design is used to control fan noise, then noise reduction is achieved, but device complexity and cost increase
Solution Approach 1:
The patent applies asymmetry by implementing a heterogeneous distribution of cutbacks where only a subset of blades have cutbacks at specific locations (leading edge, trailing edge, or both), while other blades remain unchanged. This asymmetric configuration creates a non-uniform shockwave distribution pattern that reduces noise compared to uniform blade designs, directly resolving the contradiction between noise reduction and design complexity.
2Object-affected harmful factors
If trailing edge blowing is used to control noise, then noise reduction is achieved, but manufacturing complexity increases due to drilling holes
Solution Approach 1:
The patent extracts the noise reduction function from complex active systems (like trailing edge blowing with holes) and implements it through a simple geometric modification (cutbacks) on a subset of blades. This removes the need for drilling holes and complex blowing systems, achieving noise reduction while maintaining ease of manufacture.
3Object-affected harmful factors
If variable nozzle is used to change fan running line, then noise reduction is achieved, but engine complexity, cost and weight increase
Solution Approach 1:
The patent applies local quality by modifying only a subset of blades with cutbacks at specific locations rather than changing the entire engine system with a variable nozzle. This localized modification achieves noise reduction through altered shockwave distribution without adding the weight and complexity of variable nozzle mechanisms.
4Object-affected harmful factors
If acoustic treatments are applied to fan and bypass stator vanes, then noise reduction is achieved, but device complexity increases
Solution Approach 1:
Instead of adding acoustic treatments to reduce noise, the patent inverts the approach by using geometric cutbacks on a subset of blades to alter the fundamental flow structure and shockwave distribution. This passive geometric modification achieves noise reduction without the complexity of acoustic treatment systems.
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 design achieves significant noise reduction, with up to 94% reduction in specific frequencies, and improves fan performance and bypass efficiency without increasing engine complexity or weight.
Implementation Method 1
zones of asymmetrical shockwave distribution of the flow around the rotor, such that, when in operation, a flow around the rotor has a substantially symmetrical shockwave distribution
Data Source
AI summary
A gas turbine engine includes rotor having a hub, and a plurality of blades extending generally radially from the hub. Each of the blades has an airfoil portion. The airfoil portion has a leading edge and a trailing edge defining a chordwise direction, and a root and a tip defining a spanwise direction. Only a sub-set of the blades has a cutback at at least one of the trailing edge and the leading edge. A method of designing and a method of assembling a rotor having noise reduction properties in a gas turbine engine is also presented.