Variable Cycle Compensation in Gas Turbine Engines
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Solution Overview
Problem
Existing gas turbine engines face challenges in achieving rapid thrust response due to the slower adjustment of engine thrust compared to the faster variable geometry changes.
Innovation Solution
The implementation of a variable cycle compensation system in a gas turbine engine, which includes an electric component such as a motor-generator and an actuation system like a variable area turbine or nozzle, allows for faster adjustment of power production and absorption by communicating commands based on current operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If variable geometry components are adjusted to change thrust, then thrust response speed is improved, but engine spool rotation adjustment becomes the limiting factor
Solution Approach 1:
The patent introduces a power absorption system as an intermediary component that decouples the thrust response from spool rotation inertia. This system absorbs excess power during rapid thrust changes, allowing variable geometry components to adjust thrust independently without being constrained by spool speed changes, thus resolving the coordination complexity between these two systems
Solution Approach 2:
The patent extracts the power management function from the spool rotation system by adding a dedicated power absorption system. This separation allows the variable geometry system to control thrust response while the power absorption system independently manages the energy balance, eliminating the bottleneck caused by spool inertia
2Power
If fuel flow rate is increased to accelerate spool rotation, then engine thrust is improved, but response time is slower compared to variable geometry adjustment
Solution Approach 1:
The patent implements preliminary action by having the power absorption system ready to immediately absorb excess power when variable geometry components are adjusted. This pre-positioned capability allows thrust to change rapidly through geometry adjustment without waiting for spool rotation to catch up, significantly reducing thrust adjustment time
Solution Approach 2:
The patent replaces the purely mechanical fuel-flow-to-thrust conversion with a hybrid system where power absorption (a different mechanical approach) supplements the variable geometry system. This substitution enables faster thrust response by bypassing the slower fuel flow rate adjustment and spool acceleration process
3Speed
If variable cycle system adjusts power production rapidly, then thrust response is improved, but power imbalance occurs between production and absorption
Solution Approach 1:
The patent implements feedback control where the controller continuously monitors both power production and power absorption levels, and dynamically adjusts the variable cycle system and power absorption system to maintain balance. This closed-loop control ensures rapid power adjustment while preventing instability, resolving the contradiction between speed and reliability
Solution Approach 2:
The patent makes the power absorption capacity dynamic and adjustable rather than fixed. The power absorption system can adapt its absorption rate to match the variable cycle system's power production changes, enabling rapid response while maintaining flexibility to preserve power balance 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 solution enables faster and more precise control of thrust response, reducing the dependence on spool speed inertia and enhancing the engine's ability to replicate commanded thrust profiles during events like snap acceleration or high-frequency oscillations.
Implementation Method 1
The electric component is a motor-generator... the electric component adds power as the electric motor
Implementation Method 2
the electric component absorbs power as the electric generator to produce electrical power for an aircraft use or recharging of a battery system
Implementation Method 3
The controller is further operable to... calculate a plurality of commands to a plurality of power production and absorption subsystems for adjusting the variable cycle... The output of the electric component is compensated to increase or decrease an ability of the variable cycle system to produce or absorb power
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An aspect includes a variable cycle system (210) of a gas turbine engine (20). The variable cycle system (210) includes an actuation system (205), an electric component (212), and a controller (216). The actuation system (205) is configured to adjust a variable cycle of turbomachinery (202) of the gas turbine engine (20). The electric component (212) is operable to provide a shaft power supply or a load corresponding respectively to an adjustment of the turbomachinery (202). The controller (216) is operable to adjust an output of either or both of the actuation system (205) and the electric component (212) for separate control of thrust and cycle responses.