Angled Effusion Holes Combustor Liners Noise Reduction
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Solution Overview
Problem
Current gas turbine engine combustors face challenges in reducing noise levels, particularly from pressure and acoustic vibrations within the combustion chamber, with existing solutions like Helmholtz resonators being complex to manufacture and double wall constructions only effective for specific noise frequency ranges.
Innovation Solution
A combustor design featuring inner and outer liners with angled effusion holes in both primary and secondary sections, where the density of effusion holes in the primary section is equal to or greater than in the secondary section, directing airflow at specific angles to create a time delay and decouple noise frequencies, reducing noise emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Helmholtz resonators are used as damping elements to reduce noise, then noise levels are reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies effusion holes (porous structure) in the combustor liners to reduce noise. The liners contain a plurality of effusion holes that allow controlled airflow while attenuating noise, replacing complex Helmholtz resonators with a simpler porous/effusion hole structure that achieves noise reduction without increasing manufacturing complexity
Solution Approach 2:
The patent varies the density of effusion holes in different sections of the combustor (higher density in primary section, lower density in secondary section) to optimize noise reduction across different frequency ranges. This parameter variation allows broadband noise attenuation while maintaining a simple, manufacturable structure
2Object-affected harmful factors
If double wall construction with impingement holes and effusion holes is used, then specific range of noise frequencies is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the noise reduction function from the complex double wall construction with separate impingement and effusion holes, simplifying it to a single wall structure with effusion holes that performs both cooling and noise reduction functions
Solution Approach 2:
The effusion holes in the combustor liners serve multiple functions simultaneously: they provide cooling airflow to the liner walls, reduce noise across broadband frequencies, and maintain structural integrity. This multi-functionality eliminates the need for separate impingement hole systems
3Object-affected harmful factors
If effusion hole density in primary section is equal to or greater than secondary section, then broadband low-frequency noise is attenuated, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies different effusion hole densities to different sections of the combustor: higher density in the primary combustion section and lower density in the secondary section. This local quality variation optimizes noise reduction for broadband low-frequency noise while accommodating manufacturing capabilities through clear regional differentiation rather than requiring uniform high precision across the entire structure
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 angled effusion hole design effectively attenuates broadband low-frequency noise by shifting phase and reducing amplitude, achieving noise reduction without increasing manufacturing complexity or cost, while maintaining combustion efficiency.
Implementation Method 1
directing the effusion airflow along a direction extending at a first angle with respect to a surface of the wall and at a second angle with respect to a radial plane extending radially from a central axis of the combustor to produce a time delay between a noise generated in the compressor section and at least one of a noise generated in the combustor and a noise amplified in the combustor
Implementation Method 2
The angled effusion hole design effectively attenuates broadband low-frequency noise by shifting phase and reducing amplitude
Implementation Method 3
The angled effusion hole design effectively attenuates broadband low-frequency noise by shifting phase and reducing amplitude
Data Source
AI summary
A combustor having liners with a plurality of angled effusion holes defined therethrough at a first angle with respect to a surface of the liners and at a second angle with respect to a corresponding radial plane. A density of the effusion holes defined in a primary section receiving the fuel nozzles is at least equal to a density of the effusion holes defined in a secondary downstream section.