Acoustic Shield for Compressor Bleed Slot Noise Reduction
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Solution Overview
Problem
Gas turbine engine compressors generate significant noise due to supersonic gas flow and pressure waves at the blade passing frequency, leading to 'buzz saw' noise and pressure spikes, which are not effectively mitigated by existing technologies.
Innovation Solution
A centrifugal compressor with an acoustic shield positioned adjacent to bleed slots, featuring a concave shaped wall or honeycomb liner tuned to specific frequencies, which absorbs and reflects acoustic pressure waves, reducing noise intensity without degrading compressor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bleed holes/slots are used to prevent engine surge and increase operational range, then engine reliability is improved, but compressor noise is generated and worsened
Solution Approach 1:
An acoustic shield is introduced as an intermediary element between the bleed slots and the surrounding environment. The shield blocks the direct propagation of acoustic waves from the bleed slots, reducing noise while preserving the bleed function for surge prevention and operational range extension
Solution Approach 2:
The acoustic shield utilizes the acoustic pressure waves generated by the compressor in a controlled manner. By positioning the shield to reflect and redirect these waves, the system converts the harmful noise into a controlled acoustic field that can be directed away from sensitive areas while maintaining the bleed function
2Productivity
If supersonic gas flow is used to increase compression efficiency, then productivity is improved, but buzz saw noise and pressure spikes are generated
Solution Approach 1:
The acoustic shield serves as a mediator that intercepts acoustic waves generated by supersonic flow at the blade tips. By blocking these waves before they propagate to the inlet duct, the shield reduces buzz saw noise while allowing the supersonic flow to maintain compression efficiency
Solution Approach 2:
The acoustic shield is designed to interact with the vibrational acoustic waves generated by supersonic flow. The shield's geometry and positioning enable it to dampen and dissipate these vibrations, converting the harmful acoustic energy into minimal disturbance while preserving the supersonic flow regime
3Object-generated harmful factors
If acoustic shield is positioned close to bleed slots for maximum noise reduction, then noise is reduced, but compressor performance may be degraded
Solution Approach 1:
The acoustic shield is designed with adjustable positioning capabilities, allowing the distance between the shield and bleed slots to be optimized. This dynamic adjustment enables the system to achieve maximum noise reduction while maintaining sufficient clearance to preserve compressor performance and airflow characteristics
Solution Approach 2:
The acoustic shield's design parameters including distance from bleed slots, shield geometry, and material properties are optimized to achieve the right balance. By carefully selecting these parameters, the system achieves effective noise reduction while maintaining compressor performance through controlled acoustic interference patterns
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 acoustic shield effectively reduces sound power levels by dissipating acoustic pressure waves, minimizing noise intensity while maintaining operational performance of the compressor.
Implementation Method 1
The acoustic shield is spaced at a distance from the one or more bleed slots such that acoustic pressure waves generated by the compressor are absorbed and reflected by the acoustic shield
Implementation Method 2
The acoustic shield is spaced at a distance from the one or more bleed slots such that acoustic pressure waves generated by the compressor are absorbed and reflected by the acoustic shield
Data Source
AI summary
An assembly for reducing compressor noise includes a compressor and an acoustic shield. The compressor has a rotor with a plurality of blades mounted thereto. Additionally, the compressor has one or more bleed slots therein. The acoustic shield is disposed adjacent to the one more bleed slots and spaced at a distance therefrom.