Turboprop Engine Ng-Limit Governing for Low-Power Stability
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Solution Overview
Problem
Power governing in turboprop engines is challenging, particularly at low power levels, leading to power variations and oscillations.
Innovation Solution
Implementing a power governing system that sets upper and lower limits for gas generator speed (Ng) based on power lever position, governing output power as a function of target power within these limits, and switching to maximum or minimum Ng when outside these limits to stabilize power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional power governing is used at low power levels, then the engine can operate at low power settings, but power variations and oscillations occur leading to unstable operation
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gas generator speed (Ng) based on the power lever position and operating conditions. The system modifies Ng within defined upper and lower limits to maintain stable output power, particularly at low power levels where conventional governing struggles. This involves changing the speed parameter in response to feedback from power measurements and operational state, resolving the contradiction between maintaining low power operation and ensuring operational stability.
2Power
If the power governing system allows Ng to vary freely to meet target power, then target power can be achieved, but power oscillations and variations increase
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual output power and comparing it to the target power, then adjusting the gas generator speed accordingly. The system uses feedback from power measurements and operational parameters to modify Ng within defined limits, achieving target power while maintaining stability. This closed-loop feedback mechanism resolves the contradiction between achieving target power and maintaining power stability.
Solution Approach 2:
The patent applies dynamics by making the power governing system adaptive and responsive to changing operating conditions. The gas generator speed limits and governing parameters are dynamically adjusted based on power lever position, ambient conditions, and engine state. This dynamic adaptation allows the system to achieve target power across varying conditions while maintaining stability, resolving the contradiction between power achievement and stability.
3Ease of operation
If conventional power governing is used, then the system can respond to power lever position changes, but the response causes power variations and oscillations
Solution Approach 1:
The patent applies parameter changes by smoothly transitioning the gas generator speed between defined limits in response to power lever position changes. The system modifies Ng within upper and lower bounds based on the power lever position and operating conditions, providing responsive control while minimizing power variations and oscillations. This controlled parameter adjustment resolves the contradiction between responsiveness and power stability.
Data Source
AI summary
There is provided a method and system for operating a turboprop engine of an aircraft. When a resulting value for Ng is between at least one upper limit and at least one lower limit, the output power is governed as a function of the target power. When the resulting value for Ng is on or outside of the at least one upper limit and the at least one lower limit, the output power is governed as a function of the maximum Ng and the minimum Ng.