Reversible Electric Machine Coupling for Turbine Engine Efficiency
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Solution Overview
Problem
In helicopter turbine engines, using the reversible electric machine to generate electricity during flight affects the engine's efficiency and pilotability by shifting the operating line of the compressor, leading to suboptimal compression ratios and increased specific fuel consumption.
Innovation Solution
The reversible electric machine is designed to be coupled to the free turbine after engine start-up, allowing it to generate electricity from the free turbine's kinetic energy, thereby minimizing the impact on the gas generator's efficiency and preserving acceleration capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the reversible electric machine is coupled to the gas generator to generate electricity during flight, then electrical power is supplied for onboard equipment, but the engine efficiency deteriorates due to shift in compressor operating line and increased specific fuel consumption
Solution Approach 1:
The patent extracts the energy extraction function from the gas generator and relocates it to the free turbine. The reversible electric machine is decoupled from the gas generator and coupled to the free turbine, allowing electricity generation without affecting the gas generator's operating line and compression ratio. This separation enables independent optimization of both the gas generator for efficiency and the free turbine for power extraction.
2Use of energy by moving object
If the reversible electric machine is coupled to the gas generator to generate electricity, then electrical power is available, but the helicopter pilotability deteriorates due to reduced acceleration capacity
Solution Approach 1:
The patent separates the energy extraction function from the gas generator by coupling the reversible electric machine to the free turbine instead. This allows the gas generator to maintain its full acceleration capacity and operating characteristics, while the free turbine provides the necessary kinetic energy for electricity generation without compromising pilotability.
3Use of energy by moving object
If the reversible electric machine extracts kinetic energy from the gas generator, then electricity is generated, but the compressor operating line shifts away from optimal compression ratio
Solution Approach 1:
The patent removes the energy extraction load from the gas generator and relocates it to the free turbine. This maintains the gas generator's operating line at the optimal compression ratio, ensuring maximum efficiency of the compressor-turbine-gas generator system while still providing electrical power through the free turbine-driven reversible electric machine.
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 configuration enables efficient electricity supply without significantly penalizing the engine's efficiency, maintaining better helicopter pilotability and reducing fuel consumption.
Implementation Method 1
the reversible electric machine operating as an electricity generator is driven in rotation by the free turbine, such that the kinetic energy for transformation into electrical energy is taken from the free turbine
Implementation Method 2
The gas burnt by the combustion is then exhausted at high speed. This gas then expands initially in the turbine of the gas generator so that the turbine extracts therefrom the energy needed for driving the compressor
Data Source
AI summary
A turbine engine, for example for a helicopter, the engine including a gas generator and a free turbine driven in rotation by a gas stream generated by the gas generator, the turbine engine further including a reversible electric machine for coupling to the gas generator, the reversible electric machine configured to set the gas generator into rotation during a stage of starting the turbine engine. To generate electricity, the reversible electric machine is also configured to be coupled to the free turbine after the turbine engine has started.