Variable Inlet Guide Vane for Gas Turbine Windmilling
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Solution Overview
Problem
Gas turbine engines face challenges in starting and restarting, particularly in the air, where traditional starters may not be effective at higher speeds, relying on windmilling to drive compressor and turbine rotors, which requires increasing windmilling speed for efficient airflow.
Innovation Solution
Incorporating a variable inlet guide vane and a variable area nozzle in the compressor section, controlled by a programmed system that adjusts positions based on aircraft altitude, airspeed, and low spool speed to maximize airflow and windmilling speed, combined with a gear reduction system and a starter for enhanced starting capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional starter is used to start the engine in the air, then the engine can be started at lower speeds, but the starter becomes ineffective at higher speeds
Solution Approach 1:
The inlet guide vane is made dynamically adjustable with multiple discrete positions (fully open, intermediate, closed) to adapt to different flight conditions and speed ranges, allowing the system to transition from starter-assisted starting at low speeds to windmilling starting at high speeds
Solution Approach 2:
The system changes the airflow parameter by adjusting the inlet guide vane position based on aircraft speed and altitude, optimizing the windmilling effect at high speeds while maintaining compatibility with starter operation at lower speeds
2Speed
If windmilling is relied upon for starting at higher speeds, then the starter is not needed, but the windmilling speed must be increased for efficient airflow
Solution Approach 1:
The inlet guide vane is positioned in advance to the fully open position before windmilling starts, preparing the airflow path to maximize the windmilling effect and ensure efficient airflow into the compressor section from the outset
Solution Approach 2:
The system optimizes airflow parameters by adjusting the inlet guide vane to fully open position, increasing the volume and velocity of air entering the compressor section, thereby enhancing windmilling speed and airflow efficiency simultaneously
3Speed
If the inlet guide vane is positioned to maximize airflow for windmilling, then windmilling speed increases, but airflow control during normal operation may be affected
Solution Approach 1:
The inlet guide vane system is designed with multiple discrete positions (fully open for windmilling, intermediate for transition, closed for ground starting) that are dynamically selected based on operational mode, allowing full airflow for windmilling while maintaining precise airflow control during normal operation
Solution Approach 2:
The control system uses feedback from aircraft speed, altitude, and engine parameters to automatically select the appropriate inlet guide vane position, ensuring optimal windmilling performance when needed while maintaining proper airflow control during normal engine operation
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
The solution effectively increases windmilling speed and airflow, enabling more efficient engine startup and restart, particularly in flight conditions, by optimizing airflow through the compressor section and bypass duct, thereby improving engine performance and reliability.
Implementation Method 1
a variable inlet guide vane which is movable between distinct angles to control the airflow approaching the compressor section
Implementation Method 2
Windmilling typically occurs as the compressor and fan rotors are driven by the air being forced into the core engine, and the bypass duct, as the aircraft continues to move
Implementation Method 3
The compressor section compresses air and delivers air into a combustion section
Implementation Method 4
Air in the compressor is passed downstream into a combustor section where it is mixed with fuel and ignited
Implementation Method 5
Products of this combustion pass downstream over turbine rotors, driving them, and in turn drive the compressor and fan
Data Source
AI summary
A gas turbine engine includes a compressor section, the compressor section including a variable inlet guide vane which is movable between distinct angles to control the airflow approaching the compressor section. A control is programmed to position the vane at startup of the engine to direct airflow across the compressor section. The engine includes a fan for delivering bypass air into a bypass duct positioned outwardly of a core engine including the compressor section. The position of the vane is configured to direct airflow across the compressor section while an aircraft associated with the gas turbine engine is in the air, and to increase a windmilling speed of the compressor section and the turbine rotors. A method and variable inlet vane are also disclosed.