Radial Strut Fan Case Connection for Gas Turbine Torque Management
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Solution Overview
Problem
Modern gas turbine engines with gear reduction systems face challenges in providing adequate structural support and noise reduction between the fan case and core engine, particularly with longer low pressure compressors that require improved mounting solutions to manage torque and loads effectively.
Innovation Solution
The implementation of a rigid connection between the fan case and core engine using a combination of radial struts and fan exit guide vanes, where non-structural vanes with acoustic features and structural vanes are strategically positioned to reduce noise and enhance structural integrity, with the structural vanes comprising 15-30% of the total vanes and radial struts providing additional rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fan exit guide vanes are used to connect fan case and core housing, then structural support is provided, but noise is generated during operation
Solution Approach 1:
The connection system is segmented into two functional components: structural fan exit guide vanes that provide rigid connection and acoustic features that reduce noise. This segmentation allows each component to optimize its specific function without compromising the other.
Solution Approach 2:
Acoustic features such as acoustic chambers and perforated face sheets are introduced as intermediary elements between the structural vanes and the operating environment. These intermediaries absorb and dissipate noise while allowing the structural vanes to maintain their connection function.
2Adaptability or versatility
If gear reduction is incorporated to reduce fan rotor speed, then operational flexibility is improved, but structural support requirements increase
Solution Approach 1:
The fan exit guide vanes serve multiple functions simultaneously: they provide structural support to connect the fan case to the core housing, guide airflow from the fan rotor, and through their acoustic features, reduce noise. This multi-functionality addresses the increased structural requirements without compromising operational flexibility.
Solution Approach 2:
The vanes utilize composite construction combining structural materials for rigidity with acoustic damping materials or features (such as perforated surfaces and chambers) to reduce noise. This composite approach allows the same component to meet both structural and acoustic requirements.
3Object-generated harmful factors
If non-structural vanes with acoustic features are added, then noise is reduced, but device complexity increases
Solution Approach 1:
The acoustic features are merged with the existing fan exit guide vane structure rather than being separate add-on components. The acoustic chambers and perforated face sheets are integrated into the vane design, allowing noise reduction without proportionally increasing complexity.
Solution Approach 2:
Acoustic features are applied locally to specific portions of the vanes where noise generation is most prominent, rather than uniformly across all components. This localized approach reduces noise effectively while minimizing the overall increase in device complexity.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3C
AI summary
A gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction to reduce a speed of the fan rotor relative to a speed of the fan drive turbine. A fan case (108) surrounds the fan rotor, and a core engine with a compressor section, including a low pressure compressor. The fan rotor (106) delivers air into a bypass duct defined between the fan case (108) and the core engine. A rigid connection is between the fan case (108) and the core engine including a plurality of radial struts (116, 152) rigidly connected to the fan case (108), and to the core engine. A plurality of non-structural fan exit guide vanes and the non-structural fan exit guide vanes are provided with an acoustic feature to reduce noise. The non-structural fan exit guide vanes are rigidly mounted to at least one of the fan case (108) and the core engine.