Turbomachine Acceleration Control for High- and Low-Shaft Synchronization
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Solution Overview
Problem
Aircraft turbomachines experience a time lag between the high-pressure and low-pressure shafts during acceleration due to the use of a reduction gear, leading to delayed fan acceleration and increased time to achieve target thrust.
Innovation Solution
A control method involving power injection into the high-pressure shaft followed by withdrawal to accelerate the high-pressure shaft to target speed, then transferring power to the low-pressure shaft, utilizing reversible electric machines and a control system to synchronize shaft acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a reduction gear is placed between the low-pressure shaft and the fan, then the fan speed can be reduced, but the acceleration time of the low-pressure shaft increases significantly
Solution Approach 1:
The control system performs preliminary action by detecting when the high-pressure shaft reaches a predetermined rotational speed and immediately initiating power withdrawal. This提前 action allows the low-pressure shaft to receive power transfer before the high-pressure shaft completes its full acceleration, thereby reducing the overall acceleration time despite the presence of the reduction gear
Solution Approach 2:
The control system acts as an intermediary that coordinates power transfer between the high-pressure and low-pressure shafts. By detecting the rotational speed of the high-pressure shaft and controlling the reversible electric machine, the system mediates the power flow to optimize acceleration while accommodating the reduction gear's inertial effects
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 the lag between high-pressure and low-pressure shaft accelerations, enabling faster fan acceleration and reduced time to achieve target thrust.
Implementation Method 1
a first reversible electric machine (11) connected to said high-pressure shaft (8), said first reversible electric machine (11) being able to operate, on the one hand, as an electric generator, withdrawing mechanical power from the high-pressure shaft (8), and on the other hand, as an electric motor, injecting mechanical power onto the high-pressure shaft (8)
Data Source
Figure 1~2
Figure 3
AI summary
The invention concerns a method for regulating the acceleration of a turbomachine, the turbomachine comprising a combustion chamber, a high-pressure turbine situated downstream from the combustion chamber and that rotates a high-pressure shaft, and a low-pressure turbine situated downstream from the high-pressure turbine and that rotates a low-pressure shaft, characterised in that the method comprises the following steps: - Injecting (100) mechanical power onto the high-pressure shaft until the speed of the high-pressure shaft reaches a target value, then - Drawing (200) mechanical power from the high-pressure shaft in order to maintain the speed at the target value.