Gas Turbine Flow Splitter with Helmholtz Boreholes
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Solution Overview
Problem
Modern gas turbine engines produce significant noise due to airflow interactions with the engine section stator (ESS), which escapes through the bypass duct, contributing to overall noise pollution, and existing noise reduction technologies are inadequate in addressing this specific source of noise.
Innovation Solution
The gas turbine engine incorporates a flow splitter with noise-attenuation boreholes on its external surface, which are designed as Helmholtz resonators to reduce noise by dissipating acoustic energy, featuring cylindrical or prismatic boreholes that open into an internal cavity, arranged to minimize blockage and optimize noise attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If noise-attenuation boreholes are added to the flow splitter, then noise attenuation capability is improved, but device complexity increases
Solution Approach 1:
The flow splitter incorporates multiple boreholes of varying sizes and configurations throughout its structure, creating a porous-like architecture that allows acoustic energy to enter and be dissipated within the internal cavity, effectively attenuating ESS interaction tone noise while maintaining structural integrity
Solution Approach 2:
The boreholes are arranged in a nested pattern where smaller boreholes are positioned within regions defined by larger boreholes, creating multiple levels of noise attenuation pathways that efficiently reduce noise across different frequencies without requiring a separate complex noise control system
2Loss of energy
If multiple boreholes are formed in the flow splitter, then acoustic energy dissipation is improved, but manufacturing complexity increases
Solution Approach 1:
The flow splitter is designed with modular sections where groups of boreholes are arranged in repeating patterns along the splitter structure, allowing the component to be manufactured in segments that can be assembled together, thereby reducing overall manufacturing complexity while maintaining effective noise attenuation across the entire surface
3Object-affected harmful factors
If boreholes are positioned around the leading edge, then noise attenuation is improved, but risk of blockage increases
Solution Approach 1:
The boreholes are arranged in an asymmetric pattern that is denser in regions experiencing lower contamination risk and sparser in areas more susceptible to blockage, optimizing the balance between noise attenuation effectiveness and reliability by positioning more boreholes where they are less likely to be blocked while maintaining adequate noise reduction coverage
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 implementation of noise-attenuation boreholes in the flow splitter effectively reduces ESS interaction tone noise, enhancing the overall noise reduction capabilities of the engine by dissipating acoustic energy and minimizing noise pollution.
Implementation Method 1
One or more of the boreholes may be arranged as Helmholtz resonators. The boreholes may be for acoustic attenuation of noise, and in particular, noise in or arising from the gas turbine engine.
Implementation Method 2
The boreholes may be for acoustic attenuation of noise... effectively reduces ESS interaction tone noise, enhancing the overall noise reduction capabilities of the engine by dissipating acoustic energy
Data Source
Figure 1~2
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AI summary
A gas turbine engine comprising a fan, an engine core located downstream of the fan so as to receive a first portion of flow from the fan, a bypass duct located downstream of the fan and radially outside the engine core, so as to receive a second portion of flow from the fan, and a flow splitter (23) defining the location at which the flow from the fan splits into the first and second portions, wherein the flow splitter comprises one or more noise-attenuation boreholes (40a, 40b) formed in an exterior surface (30) of the flow splitter.