Fan Case-Core Housing Strut Frame for Rigidity and Noise Reduction
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Solution Overview
Problem
In modern gas turbine engines with gear reduction, the structural fan exit guide vanes provide insufficient support for the fan case to the core housing, especially with longer low pressure compressors, leading to mounting challenges and potential instability.
Innovation Solution
Implementing a combination of radial struts and non-structural fan exit guide vanes with acoustic features, such as chambers and perforated face sheets, to provide additional rigidity and structural support between the fan case and core engine, while reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If structural fan exit guide vanes are used to provide support between fan case and core housing, then mounting is simplified, but structural integrity and stability are insufficient especially with longer low pressure compressors
Solution Approach 1:
The support structure is segmented into multiple functional components: radial struts for primary structural support, structural fan exit guide vanes for additional rigidity, and non-structural fan exit guide vanes for aerodynamic guidance. This segmentation allows each component to be optimized for its specific function while collectively providing the required structural integrity and ease of assembly.
Solution Approach 2:
The invention merges structural and non-structural fan exit guide vanes into a single integrated assembly that serves dual purposes: providing structural support through the rigidly mounted structural vanes and acoustic noise reduction through the non-structural vanes with acoustic features. This combination eliminates the need for separate structural supports while maintaining overall structural integrity.
2Reliability
If structural fan exit guide vanes are used, then some support is provided, but additional rigidity is needed for longer low pressure compressors
Solution Approach 1:
The radial struts are pre-installed to establish the primary structural framework between the fan case and core engine before the fan exit guide vanes are mounted. This preliminary structural support ensures that the assembly maintains adequate rigidity and stability, particularly for longer low pressure compressors, before additional components are added.
Solution Approach 2:
The support structure utilizes a composite arrangement of different vane types: structural fan exit guide vanes made from rigid materials for mechanical support, and non-structural vanes with acoustic features for noise reduction. This composite structure provides both the required rigidity and additional functional benefits without compromising overall stability.
3Strength
If traditional fan exit guide vanes are used, then structural support is provided, but noise emissions are not reduced
Solution Approach 1:
The fan exit guide vane assembly is designed to perform multiple functions simultaneously: structural fan exit guide vanes provide structural support and rigidity, while non-structural fan exit guide vanes with acoustic features (chambers and perforated face sheets) provide noise reduction. This multi-functional design eliminates the need for separate structural and acoustic components.
Solution Approach 2:
The non-structural fan exit guide vanes act as intermediary elements between the structural components and the external environment. These vanes with acoustic features absorb and dampen noise generated by the fan while allowing the structural vanes to maintain their load-bearing function, thus mediating between structural requirements and noise control.
Data Source
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 surrounds the fan rotor, and a core engine with a compressor section, including a low pressure compressor. The fan rotor delivers air into a bypass duct defined between the fan case and the core engine. A rigid connection is between the fan case and the core engine including a plurality of radial struts rigidly connected to the fan case, 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 and the core engine.