Variable Guide Vane Control for Engine Transient Response
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Solution Overview
Problem
Existing methods for controlling transient power responses in gas turbine engines, such as active bleed valve actuation and passive actuation, either increase weight or decrease efficiency, and alternative techniques like casing treatment lower overall efficiency.
Innovation Solution
A system and method utilizing a variable geometry mechanism with a control unit, including a VGV position control module and an acceleration rate control module, dynamically adjusts the position of variable guide vanes to optimize engine response during rapid power transitions, enhancing inlet mass flow and acceleration rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If active bleed valve actuation is used to increase inlet mass flow and reduce response time, then engine transient response is improved, but engine weight increases
Solution Approach 1:
The patent extracts the bleed valve actuation function from the active control system and replaces it with a passive geometric solution. The variable guide vanes are configured to passively redirect airflow, eliminating the need for active bleed valve actuation mechanisms and their associated actuators, sensors, and control electronics, thereby reducing engine weight while maintaining improved transient response.
Solution Approach 2:
The variable guide vanes serve as an intermediary mechanism that mediates between the compressor inlet and the bleed valve system. By adjusting the guide vane angles, the system controls airflow distribution to achieve the desired transient response without requiring direct active bleed valve actuation, thus reducing the weight of moving components.
2Loss of time
If passive bleed valve actuation is used to increase inlet mass flow, then response time is reduced, but gas path temperature increases and gas generator speed decreases
Solution Approach 1:
The patent changes the geometric parameters of the variable guide vanes to optimize airflow distribution. By adjusting the guide vane angles dynamically, the system controls the mass flow rate and its distribution across the compressor, achieving rapid transient response while maintaining gas path temperature within acceptable limits and preventing excessive gas generator speed increases.
3Loss of time
If the running line is lowered to improve transient engine performance, then response time is reduced, but overall efficiency decreases and specific fuel consumption increases
Solution Approach 1:
The patent implements a dynamic control system that adjusts the variable guide vane positions in real-time based on engine operating conditions. This dynamic adjustment allows the system to optimize the running line position dynamically, achieving rapid transient response when needed while maintaining optimal efficiency during steady-state operation, thus resolving the contradiction between response time and overall efficiency.
4Loss of time
If casing treatment is used to improve transient response, then response time is reduced, but engine efficiency decreases
Solution Approach 1:
The patent segments the compressor inlet flow into multiple controllable streams using the variable guide vanes. Each set of guide vanes can be independently adjusted to control specific airflow paths, allowing precise management of mass flow distribution to achieve rapid transient response without the efficiency penalties associated with conventional casing treatment that affects the entire compressor periphery.
Data Source
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AI summary
There is provided a system (100) and method for controlling an engine (10). A request signal indicative of a demand for the engine (10) to output a required power level is first received. A position control signal is then generated in response to the request signal. The position request signal is indicative of a first request for adjusting a present position of a variable geometry mechanism of the engine towards a commanded position to achieve the required power level. An acceleration rate control signal is further generated on the basis of the position control signal. The acceleration rate control signal is indicative of a second request for adjusting an acceleration rate of the engine in accordance with the commanded position of the variable geometry mechanism. The position control signal and the acceleration rate control signal are then output to the engine (10).