Gas Turbine Vane Leading Edge Thickness for Noise Reduction
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Solution Overview
Problem
Gas turbine engines with variable area fan nozzles and fan exit guide vanes generate noise due to upstream turbulence interactions, which increases the total effective perceived noise level (EPNL) during flight conditions.
Innovation Solution
The design includes a second airflow structure with a leading edge region whose thickness is based on the wake thickness produced by the first airflow structure, and a vane with a suction surface, pressure surface, and leading edge region that forms a profile parallel to the velocity profile of the wake, optimizing the leading edge thickness to reduce noise generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fan exit guide vanes are used to de-swirl airflow, then aerodynamic performance is improved, but noise is generated due to turbulence interaction
Solution Approach 1:
The leading edge of the fan exit guide vane is designed with a non-uniform thickness distribution, where the thickness varies along the span to match the wake thickness from the upstream blade. This local variation in geometry allows the vane to interact differently with the turbulent wake in different regions, reducing noise generation while maintaining overall aerodynamic performance.
Solution Approach 2:
The invention changes the geometric parameter of the leading edge thickness based on the wake characteristics. By adjusting the leading edge thickness to be proportional to the wake thickness, the flow interaction is modified to reduce turbulence-induced noise while preserving the de-swirling function.
2Productivity
If variable area fan nozzle is used to modulate engine cycle, then engine performance is optimized, but noise is generated due to upstream turbulence interaction
Solution Approach 1:
The fan exit guide vane leading edge is designed with spatially varying thickness properties that are tailored to the local wake conditions. This local optimization allows the nozzle to modulate engine performance while minimizing noise generation at critical locations where turbulence interaction occurs.
3Object-generated harmful factors
If leading edge thickness is reduced to minimize wake interaction, then noise is reduced, but aerodynamic performance may be compromised
Solution Approach 1:
Rather than uniformly reducing the leading edge thickness, the invention applies a non-uniform thickness distribution that is optimized for each spanwise location. This allows noise reduction in regions where wake interaction is most problematic while maintaining sufficient thickness in regions where aerodynamic performance is critical.
Solution Approach 2:
The leading edge thickness is designed to dynamically adapt to the wake characteristics through its geometric profile. The thickness distribution is optimized to provide the right balance between noise reduction and performance maintenance under different operating conditions.
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 approach reduces noise levels by up to 5 dB in sound power level, particularly in the dominant frequency range, while maintaining aerodynamic performance and minimizing impact on fan nozzle exit area.
Implementation Method 1
The second airflow structure includes a leading edge region. A thickness of the leading edge region is based on a thickness of a wake in the airflow produced by the first airflow structure when the airflow passes between the first airflow structure and the second airflow structure.
Data Source
AI summary
A gas turbine engine includes a first airflow structure and a second airflow structure disposed aft of the first airflow structure. The second airflow structure includes a leading edge region. A thickness of the leading edge region is based on a thickness of a wake in the airflow produced by the first airflow structure when the airflow passes between the first airflow structure and the second airflow structure.