Gas Turbine Flow Guide Apertures for Acoustic Attenuation
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Solution Overview
Problem
Gas turbine engines face challenges in acoustic attenuation, particularly in reducing vibratory loads caused by acoustic waves and structural resonance, which can lead to instability and flutter in components like seals due to insufficient damping.
Innovation Solution
The introduction of a flow guide assembly with strategically arranged apertures along its length, increasing in open area percentage from an acoustic-structural coincidence frequency point to the outlet, disrupts acoustic waves by dissipating them through grazing flow and jetting effects, thereby reducing the likelihood of resonance and enhancing aeromechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic attenuation is increased by adding damping structures, then vibratory loads are reduced, but device complexity increases
Solution Approach 1:
The flow guide assembly incorporates a porous structure with multiple apertures distributed across its surface. This porous configuration allows acoustic waves to interact with the structure through grazing flow and jetting effects at the aperture edges, dissipating acoustic energy without requiring additional damping materials or complex attenuation structures.
Solution Approach 2:
The apertures in the flow guide assembly utilize the existing flow field to provide acoustic attenuation. The grazing flow and jetting effects generated by the apertures themselves create the damping mechanism, eliminating the need for separate active damping systems or complex acoustic treatment structures.
2Object-affected harmful factors
If apertures are added to the flow guide assembly for acoustic attenuation, then acoustic waves are disrupted, but flow pressure may be affected
Solution Approach 1:
The apertures are strategically distributed across the flow guide assembly with varying local characteristics. The aperture distribution is optimized to provide acoustic attenuation through grazing flow and jetting effects while maintaining adequate flow pressure. Local variations in aperture size, spacing, and orientation allow different regions to serve different acoustic frequencies without compromising overall flow pressure.
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 effectively attenuates acoustic waves, reducing vibratory loads and the risk of flutter, while maintaining flow pressure and structural integrity, thus improving the durability and stability of gas turbine engine components.
Implementation Method 1
disrupts acoustic waves by dissipating them through grazing flow and jetting effects
Implementation Method 2
disrupts acoustic waves by dissipating them through grazing flow and jetting effects
Data Source
Figure 1
Figure 2
Figure 3~4C
AI summary
A section (100) for a gas turbine engine (20) includes a rotating structure, a stationary structure (89), and a flow guide assembly (78, 178, 278, 378) arranged generally between the rotating structure and the stationary structure (89). A flow path (80) is defined between the flow guide assembly (78, 178, 278, 378) and one of the rotating structure and the stationary structure (89). The flow guide assembly (78, 178, 278, 378) includes a plurality of apertures (82, 182, 282, 382) configured to disrupt acoustic waves of air in the flow path (80). A seal (76) is configured to establish a sealing relationship between the rotating structure and the stationary structure (89), and wherein an inlet (80a) to the flow path (80) is adjacent the seal (76). A gas turbine engine (20) and a method of disrupting acoustic waves in a flow path (80) of a gas turbine engine (20) are also disclosed.