Bleed Valve Tortuous Flow Path for Gas Turbine Noise Reduction
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Solution Overview
Problem
Gas turbine engines generate undesirable noise due to the venting of high pressure air, which is disruptive during low power operations like aircraft approach or ground operations, affecting nearby residents and ground crew.
Innovation Solution
A bleed valve with a housing defining a tortuous path using multiple rings and swirl vanes is employed to reduce the pressure of the vented air, incorporating serrated terminal segments and angled vanes to minimize noise by reducing turbulent kinetic energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure air is vented directly from the compressor section, then the venting function is achieved, but undesirable noise is generated due to mixing with lower pressure air in the fan bypass duct
Solution Approach 1:
The venting path is segmented into multiple sections using a series of rings (first ring, second ring, third ring, fourth ring) spaced apart from each other. This segmentation creates a tortuous path that divides the direct high-pressure venting into staged pressure reductions, thereby reducing noise while maintaining the venting function.
Solution Approach 2:
The housing defines a tortuous path using curved and angled surfaces, including rings positioned at different angles and swirl vanes that create rotational flow. This curvature transforms the direct linear flow into a multi-directional tortuous path, reducing pressure gradually and minimizing noise generation.
2Object-generated harmful factors
If a tortuous path with multiple rings is used to reduce pressure, then noise is reduced, but device complexity increases
Solution Approach 1:
Multiple functional elements (rings for pressure reduction, swirl vanes for flow rotation, serrations for turbulence control) are merged into a single integrated housing structure. This consolidation achieves noise reduction through multiple mechanisms while avoiding the complexity of separate components for each function.
Solution Approach 2:
The housing serves multiple functions simultaneously: it defines the tortuous path, positions the rings and swirl vanes, provides structural support, and guides the fluid flow. This multi-functionality reduces the need for additional specialized components, thereby managing complexity while achieving noise reduction.
3Object-generated harmful factors
If swirl vanes and serrations are added to reduce turbulent kinetic energy, then noise is further reduced, but manufacturing complexity increases
Solution Approach 1:
Serrations are applied locally at specific positions on the rings rather than throughout the entire housing structure. This localized application of complexity achieves the desired reduction in turbulent kinetic energy and noise while minimizing the overall manufacturing complexity by limiting intricate features to only where they are most effective.
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 reduces noise by minimizing turbulent kinetic energy levels and peak Mach numbers, thereby reducing the mixing noise associated with venting high pressure air from gas turbine engines.
Implementation Method 1
The housing defines a tortuous path for the fluid flow from the inlet to the outlet configured to reduce a pressure of the fluid flow from the inlet to the outlet within the housing
Implementation Method 2
The terminal segment includes a plurality of serrations. The at least one swirl vane is coupled within the housing at an angle relative to a central axis that extends through the housing
Data Source
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AI summary
A bleed valve for a gas turbine engine includes a housing that defines an inlet upstream from an outlet. The bleed valve includes a poppet movable relative to the housing between a first position, in which the poppet closes the inlet, and a second position, in which the inlet is open and configured to receive a fluid flow. The housing defines a tortuous path for the fluid flow from the inlet to the outlet configured to reduce a pressure of the fluid flow from the inlet to the outlet within the housing. The tortuous path is defined by a plurality of rings positioned about the poppet, with each ring of the plurality of rings spaced apart from an adjacent ring of the plurality of rings between the inlet and the outlet to define the tortuous path.