Aircraft Propulsion Start-Up Control for Dual-Range Ignition
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Solution Overview
Problem
Existing aircraft gas turbine start-up strategies are inefficient and unreliable, requiring a stabilisation phase that prolongs the start-up time and increases the risk of over-temperature issues.
Innovation Solution
A propulsion system with a start-up control device that allows ignition of the combustion chamber in two distinct rotational speed ranges, eliminating the need for a stabilisation phase by activating ignition equipment during acceleration, and includes a control device to manage ignition attempts across these ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stabilisation phase is implemented during start-up to maintain rotational speed at a bearing speed, then the ignition equipment can be activated ready for use, but the start-up time is prolonged
Solution Approach 1:
The patent applies preliminary action by activating the ignition equipment during the acceleration phase before reaching the second ignition range, rather than waiting for a stabilisation phase. The control device is designed to activate ignition equipment such as spark plugs or igniters while the compressor shaft is still accelerating, so that ignition is ready to occur immediately when the shaft enters the second ignition range, eliminating the need for a time-consuming stabilisation phase.
Solution Approach 2:
The patent utilizes parameter changes by identifying and exploiting two distinct ignition ranges at different rotational speeds. The combustion chamber can be ignited in a first ignition range at lower speeds or a second ignition range at higher speeds (at least 40% of nominal speed). The control device monitors rotational speed and selects the appropriate ignition range, enabling rapid transition to the second range for faster start-up without requiring intermediate stabilisation.
2Productivity
If the compressor shaft is accelerated directly to high regime without stabilisation phase, then start-up time is reduced, but the risk of over-temperature and operability problems increases
Solution Approach 1:
The patent implements feedback through the control device that continuously monitors the rotational speed of the compressor shaft and the state of the combustion chamber. Based on this feedback, the control device determines when the shaft has entered the second ignition range and automatically activates the ignition equipment at the optimal moment. This closed-loop control ensures that rapid acceleration to high regime does not compromise reliability, as ignition occurs precisely when conditions are favorable.
Solution Approach 2:
The control device performs preliminary assessment of operating conditions during acceleration and prepares the ignition system in advance. By monitoring parameters such as rotational speed and atmospheric conditions, the control device ensures that ignition will occur at the optimal moment in the second ignition range, preventing over-temperature issues while maintaining rapid start-up capability.
3Reliability
If ignition is attempted only in the first ignition range at low rotational speed, then ignition can occur, but the start-up process requires unnecessary delay
Solution Approach 1:
The patent applies dynamics by making the ignition capability adaptive to the rotational speed regime. Instead of being restricted to a fixed low-speed ignition range, the system dynamically recognizes two distinct ignition ranges: a first range at lower speeds and a second range at higher speeds (at least 40% of nominal speed). The control device adjusts its strategy based on the current rotational speed, enabling the system to exploit the faster second ignition range when conditions permit, thereby improving start-up speed while maintaining reliable ignition capability.
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
Reduces start-up time, improves reliability and reproducibility by eliminating the need for a stabilisation phase and reducing the risk of over-temperature, while ensuring rapid ignition and restart capabilities.
Implementation Method 1
an electric starter for driving the compressor shaft
Implementation Method 2
an ignition device for igniting the combustion chamber
Implementation Method 3
a combustion chamber
Data Source
AI summary
A propulsion system includes a gas turbine designed so that a combustion chamber can be ignited in a first ignition range of rotational speeds of a compressor shaft. The system further includes a control device designed to control an electric starter to accelerate the compressor shaft and, when the compressor shaft is accelerated, to control an attempt to ignite the combustion chamber. The gas turbine is designed so that the combustion chamber can be ignited in a second ignition range which is higher than the first ignition range, but not between these two ignition ranges, and the ignition attempt is carried out in the second ignition range.