Gas Turbine Fan Acoustic Attenuator Design
Solution Overview
Problem
Modern gas turbine engines experience significant acoustic noise due to airflow interactions with the fan and engine section stator, which reflects and refracts within the engine, leading to noise pollution that is difficult to attenuate effectively in the interstage flow region.
Innovation Solution
A gas turbine engine design incorporating an acoustic attenuator on the radially-inner boundary of the interstage flow region, comprising multiple components such as the fan root platform, fan seal structure, and stator root platform, which are equipped with acoustically attenuating materials or Helmholtz resonators to absorb or cancel acoustic waves, forming a continuous or partially continuous radially-inner boundary to reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic attenuators are added to the interstage flow region, then noise attenuation is improved, but device complexity increases
Solution Approach 1:
The acoustic attenuator incorporates porous absorptive material that allows acoustic waves to pass through while being absorbed, converting sound energy into thermal energy through viscous dissipation in the porous structure. This effectively attenuates noise in the interstage flow region without requiring complete blockage of the flow path.
Solution Approach 2:
The acoustic attenuator is nested within the existing interstage flow region, utilizing the space between the fan and engine section stator. The attenuator is positioned on the radially-inner boundary and extends axially within the available space, fitting into the existing engine architecture rather than adding external components.
2Object-affected harmful factors
If acoustic attenuator is placed on radially-inner boundary, then noise attenuation is improved, but manufacturing precision requirements increase
Solution Approach 1:
The acoustic attenuator comprises a shell structure that defines the radially-inner boundary of the interstage flow region. This shell can be formed as a continuous or segmented structure that is relatively simple in geometry, reducing manufacturing complexity while still effectively containing the acoustic attenuating material and defining the flow path.
3Object-affected harmful factors
If acoustic attenuator covers entire radially-inner boundary, then noise attenuation is improved, but loss of substance increases
Solution Approach 1:
The use of porous absorptive material allows the acoustic attenuator to be permeable to air flow while absorbing acoustic energy. The porous structure provides flow paths through the attenuator material, minimizing flow blockage while maintaining acoustic attenuation effectiveness across the radially-inner boundary.
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 solution effectively attenuates acoustic noise in the interstage flow region, reducing the overall noise level of the gas turbine engine by absorbing or canceling acoustic waves, thereby addressing the challenge of noise pollution from gas turbine engines.
Implementation Method 1
an acoustic attenuator provided on at least a portion of a rotatable section of a radially-inner boundary of the interstage region to attenuate acoustic waves in the interstage flow region
Implementation Method 2
the acoustic attenuator may comprise a shell and porous absorptive material contained by the shell
Implementation Method 3
or Helmholtz resonators to absorb or cancel acoustic waves
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A gas turbine engine comprising: a fan comprising a plurality of fan blades; a support structure downstream of the fan comprising an engine section stator configured to guide air received from the fan, the fan being rotatable with respect to the engine section stator; an interstage flow region defined between the fan blades and the engine section stator; and an acoustic attenuator provided on at least a portion of a radially-inner boundary of the interstage region to attenuate acoustic waves in the interstage flow region.