Acoustic Resonator Insert for Gas Turbine Airfoils
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Solution Overview
Problem
Conventional acoustic liners in gas turbine engines face space constraints and inefficiencies in treating noise due to non-optimal resonator lengths and limited surface area coverage, particularly in Fan Exit Guide Vanes (FEGVs), leading to suboptimal noise attenuation.
Innovation Solution
The introduction of an acoustic impedance control feature with acoustic resonator cells that satisfy specific length-to-depth and area ratio relationships, allowing for stacked resonator cells and integral formation with airfoils, enhancing acoustic damping without increasing physical size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional quarter-wave resonators with straight constant-area channels are used, then acoustic noise attenuation is achieved, but the required resonator depth is too large for practical space constraints in airfoils
Solution Approach 1:
The patent implements nested resonator cells where a first resonator cell is stacked on a second resonator cell, with the backing chambers fluidly connected through the second neck. This nesting arrangement allows multiple resonator volumes to be compacted into a reduced depth footprint while maintaining the acoustic resonance function for noise attenuation
Solution Approach 2:
The patent transitions from conventional straight constant-area channels to bent or curved channels that change direction within the resonator cell. This dimensional reconfiguration allows the acoustic path length to be extended in a compact space, achieving the required quarter-wave resonance length without increasing the linear depth of the resonator
2Object-affected harmful factors
If acoustic treatment is applied to airfoils with limited surface area, then some noise reduction is achieved, but the coverage is insufficient for effective overall noise control
Solution Approach 1:
The patent integrates acoustic resonator cells directly into the airfoil structure itself, making the noise attenuation function a local property of the airfoil rather than an add-on treatment. This allows the entire airfoil surface to potentially serve acoustic functions while maintaining aerodynamic performance
Solution Approach 2:
The airfoil structure serves dual functions: maintaining aerodynamic flow control and providing acoustic noise attenuation through integrated resonator cells. This multi-functionality maximizes the utility of the airfoil surface area without requiring separate dedicated acoustic treatment components
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
This solution achieves up to 70% reduction in required depth for acoustic damping while maintaining or improving absorption bandwidth, enabling effective noise reduction in gas turbine engines.
Implementation Method 1
GB 2005384A discloses a lining for a fluid-flow duct incorporating resonators of a Helmholtz type
Implementation Method 2
Conventional acoustic liners rely on quarter-wave resonances of straight constant-area channels
Data Source
Figure 1
Figure 2
Figure 3~4B
AI summary
An acoustic resonator (900, 1000) having a backing chamber (508, 512, 608, 612, 722, 822, 912, 1012) defining a respective volume V and a neck (506, 510, 606, 610, 720, 820, 910, 1010) arranged relative to the backing chamber and defining an opening (614, 718, 818, 916, 1016), wherein the neck has a length and a cross-sectional area. The acoustic resonator cell (502, 504, 602, 604, 714, 814, 906, 1006) satisfies the following relationships: (1) l/L = 0.2-0.8, where l is a length of the neck (506, 510, 606, 610, 720, 820, 910, 1010) and L is a depth of the backing chamber and (2) a/A = 0.02-0.20, where a is a cross-sectional area of the neck and A is a cross-sectional area of the backing chamber (508, 512, 608, 612, 722, 822, 912, 1012).