Variable Pitch Outlet Guide Vanes for Gas Turbine Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current gas turbine engines emit significant noise during takeoff and landing operations, contributing to community and cabin noise, which exceeds acceptable levels and violates regulations, necessitating a solution to reduce noise while maintaining thrust levels.
Innovation Solution
A control system that adjusts the pitch angle of fan blades, outlet guide vanes, and speed of the fan to optimize thrust split between unducted and ducted streams, using controllers to independently manage engine geometries and operating conditions to reduce noise and maintain overall engine thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the fan speed and outlet guide vane pitch angle are increased to maintain thrust during takeoff and landing, then engine performance is improved, but noise emissions increase and exceed regulatory limits
Solution Approach 1:
The patent applies dynamics by making the outlet guide vanes variable-pitch rather than fixed, allowing the pitch angle to be dynamically adjusted based on operating conditions. The controller modifies the pitch angle of the outlet guide vanes in response to detected fan speeds and noise-sensitive conditions, enabling the engine to maintain thrust while reducing noise during takeoff and landing operations
Solution Approach 2:
The patent changes physical parameters by adjusting both the fan speed and outlet guide vane pitch angle as controllable variables. The controller modifies these parameters dynamically - reducing fan speed and adjusting outlet guide vane pitch angle - to achieve noise reduction while maintaining acceptable thrust levels during noise-sensitive operations
2Object-generated harmful factors
If the fan speed is reduced to lower noise emissions, then noise regulations are complied with, but engine thrust and performance decrease
Solution Approach 1:
The system dynamically adjusts the outlet guide vane pitch angle in response to fan speed reductions. When the controller detects reduced fan speed (which lowers noise), it simultaneously modifies the outlet guide vane pitch angle to compensate for thrust loss, ensuring that noise reduction does not come at the expense of excessive thrust degradation
Solution Approach 2:
The controller uses feedback from fan speed detection and noise-sensitive condition monitoring to continuously adjust both fan speed and outlet guide vane pitch angle. This closed-loop control ensures that thrust requirements are met while maintaining noise emissions within regulatory limits during takeoff and landing
Data Source
AI summary
Systems and methods for controlling an unducted turbofan engine to limit noise. The unducted turbofan engine may include an unducted fan drivingly coupled with a low-pressure turbine and a plurality of unducted outlet guide vanes. The unducted fan may include a plurality of fan blades and a pitch angle of the fan blades may be variable. A pitch angle of the unducted outlet guide vanes may be variable. A controller is configured to control the engine to limit noise based on a noise sensitive condition.