Three-Stream Gas Turbine Fan Layout for Noise-Efficiency Balance
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Solution Overview
Problem
Gas turbine engines face challenges in achieving a balance between increased thrust generation, reduced noise, and high propulsive efficiency due to limitations in fan diameter, weight, and thermal demands, with conventional noise reduction methods being insufficient for stringent community noise requirements.
Innovation Solution
A three-stream gas turbine engine design incorporating specific acoustic spacing between fan blades and outlet guide vanes, along with targeted airflow ratios through the bypass and core ducts, to optimize noise reduction and propulsive efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If fan diameter is increased to generate more thrust, then thrust generation is improved, but weight and packaging constraints are worsened
Solution Approach 1:
The patent changes the acoustic spacing parameter between fan blades and outlet guide vanes to optimize noise reduction while maintaining thrust generation, rather than simply increasing fan diameter to increase thrust
2Object-generated harmful factors
If conventional noise reduction methods are applied, then some noise reduction is achieved, but stringent community noise requirements are not met
Solution Approach 1:
The patent applies parameter changes by optimizing the acoustic spacing between fan blades and outlet guide vanes within specific ranges (0.05 to 0.2 times the fan blade diameter) to achieve noise reduction that meets stringent community noise requirements
Solution Approach 2:
The patent employs variable geometry outlet guide vanes that can adjust their position dynamically to optimize acoustic spacing under different operating conditions, enabling consistent noise reduction across various engine states
3Object-generated harmful factors
If acoustic spacing is optimized for noise reduction, then noise generation is reduced, but propulsive efficiency must be maintained
Solution Approach 1:
The patent optimizes acoustic spacing parameters to reduce noise while maintaining propulsive efficiency by ensuring the spacing falls within specific ranges that balance acoustic performance with aerodynamic efficiency
Solution Approach 2:
Variable geometry outlet guide vanes allow dynamic adjustment of acoustic spacing to maintain optimal noise reduction and propulsive efficiency across different operating conditions, preventing efficiency penalties
4Use of energy by moving object
If airflow ratios through bypass and core ducts are adjusted, then propulsive efficiency is improved, but thermal management demands increase
Solution Approach 1:
The patent adjusts airflow ratio parameters between bypass and core ducts to optimize propulsive efficiency while managing thermal demands through controlled air distribution
Data Source
AI summary
A gas turbine engine includes a turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct; a primary fan driven by the turbomachine; a nacelle surrounding the primary fan; and a secondary fan located downstream of the primary fan within the inlet duct. The gas turbine engine is characterized by a thrust to power airflow ratio, a core bypass ratio, a blade effective acoustic length, an acoustic spacing length, and an inlet-to-nacelle ratio.