Segmented Variable Fan Outlet Guide Vanes for Airflow Distortion Control
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Solution Overview
Problem
Fan blades in gas turbine engines experience operability issues due to variations in intake airflow and pressure fluctuations, leading to inefficiencies and performance degradation.
Innovation Solution
A fan assembly with a variable leading edge outlet guide vane assembly that includes independently rotating tip and hub segments, controlled by actuation assemblies, to adjust the direction of fan exit air and reduce incidence, allowing for flexible management of airflow distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed outlet guide vane assembly is used, then the structure is simple, but it cannot accommodate variations in intake airflow and pressure fluctuations
Solution Approach 1:
The outlet guide vane assembly is divided into multiple independently rotatable vanes with segmented structures (leading edge portion, mid portion, trailing edge portion). Each segment can be independently positioned to accommodate different airflow conditions, allowing the system to adapt to varying intake airflow and pressure fluctuations without requiring a complete redesign of the entire assembly.
Solution Approach 2:
The outlet guide vane assembly transitions from a fixed structure to a dynamic one where individual vanes and their segments can rotate independently about their spanwise axes. This dynamic capability enables real-time adjustment to match changing airflow conditions, resolving the contradiction between adaptability and structural simplicity.
2Adaptability or versatility
If the entire leading edge rotates as a single unit, then the structure is simple, but it cannot provide independent control of different spanwise sections
Solution Approach 1:
The leading edge is segmented into multiple independently rotatable sections (first leading edge segment, second leading edge segment, etc.), each capable of independent rotation about the spanwise axis. This segmentation enables differentiated control of various spanwise sections to address localized airflow distortions while maintaining a relatively simple overall structure.
Solution Approach 2:
Different spanwise sections of the outlet guide vane can be positioned at different angles to optimize performance for specific local airflow conditions. This local quality approach allows targeted correction of airflow distortions at different radial positions without affecting other sections, providing precise control where needed.
3Reliability
If outlet guide vanes are used to correct airflow distortions, then fan operability improves, but the device complexity increases
Solution Approach 1:
The outlet guide vane assembly incorporates dynamic rotation capabilities allowing individual vanes to adjust their pitch angles in response to varying airflow conditions. This dynamic adjustment improves fan operability and reliability by maintaining optimal airflow angles across different operating conditions without requiring an overly complex fixed structure.
Solution Approach 2:
The outlet guide vanes are positioned and angled in advance to pre-correct anticipated airflow distortions before they reach the fan inlet. This preliminary action prevents operability issues before they occur, improving reliability while using a relatively straightforward mechanical arrangement.
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
Enhances fan operability and performance by accommodating complex intake and inlet duct geometries, maintaining airflow stability, and improving efficiency and performance margins under varying conditions.
Implementation Method 1
the leading edge portion includes a first tip segment configured to rotate about a leading edge pitch axis and a first hub segment located radially inward of and separate from the first tip segment, the first hub segment configured to independently rotate about the leading edge pitch axis relative to the first tip segment
Implementation Method 2
configured to adjust a direction of incoming fan exit air received from the plurality of fan blades and reduce incidence between the outlet guide vane assembly and the fan exit air
Data Source
AI summary
A fan assembly for a gas turbine engine includes a fan duct, a fan, and an outlet guide vane assembly located in the fan duct axially downstream of the fan. The outlet guide vane assembly includes a first variable leading edge outlet guide vane that extends radially relative to the central axis and includes a leading edge portion and a fixed aft portion, the leading edge portion including a tip segment configured to rotate about a leading edge pitch axis and a hub segment located radially inward of and separate from the tip segment, the hub segment configured to independently rotate about the leading edge pitch axis relative to the tip segment. The assembly further includes two unique actuation assemblies each configured to rotate one of the tip and hub segments.