Manifold Pressure Damping Assembly for Turbofan Fuel Flow Oscillations
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Solution Overview
Problem
Turbofan engines experience high-frequency fuel flow oscillations due to fuel-coupled combustor dynamics, which can degrade engine performance and efficiency, and existing solutions either impact emissions and Specific Fuel Consumption (SFC) or add weight and cost to the engine.
Innovation Solution
A manifold pressure damping assembly that includes one or more closed volumes coupled in flow communication with the manifold through flow restrictors, operating passively to dampen pressure oscillations within a desired frequency range without additional control or modulation, breaking the instability loop formed by combustor, engine vibration, and fuel manifold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active tuning devices are incorporated to mitigate fuel-coupled combustor dynamics, then fuel flow oscillations are reduced, but weight and cost increase
Solution Approach 1:
A passive acoustic impedance device is introduced as an intermediary element between the fuel manifold and the combustor. This device mediates the pressure oscillations by providing acoustic impedance that disrupts the feedback loop, reducing fuel flow oscillations without requiring active control systems or adding significant weight to the engine.
2Object-affected harmful factors
If active tuning devices are incorporated to mitigate fuel-coupled combustor dynamics, then fuel flow oscillations are reduced, but cost increases
Solution Approach 1:
The patent employs a simple passive acoustic impedance device that can be manufactured at low cost using basic materials and construction methods. Rather than expensive active control systems, this approach uses a straightforward structural solution that is easy to manufacture and maintain, significantly reducing the cost burden while effectively mitigating fuel flow oscillations.
3Object-affected harmful factors
If main fuel flow is limited to avoid acoustic zone, then fuel-coupled combustor dynamics are mitigated, but emissions and SFC deteriorate
Solution Approach 1:
The patent extracts the problematic acoustic feedback loop from the system by introducing a passive acoustic impedance device that isolates the fuel manifold from combustor pressure oscillations. This allows the engine to operate at optimal fuel flow rates without being constrained by acoustic zone limitations, thereby maintaining efficient fuel consumption and emissions performance while still mitigating fuel-coupled combustor dynamics.
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 reduces the need to manage fuel-coupled acoustics, enhancing operational efficiency and reducing operational limitations, while being cost-effective and lightweight, suitable for various engine fuel manifolds.
Implementation Method 1
one or more closed volumes coupled in flow communication with a manifold through one or more flow restrictors... effectively reduces the need to manage fuel-coupled acoustics... dampen pressure oscillations within a desired frequency range
Data Source
AI summary
A manifold pressure damping assembly that includes one or more closed volumes coupled in flow communication with a manifold through one or more flow restrictors is provided.