Variable-Speed Auxiliary Power Unit for Aircraft
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Solution Overview
Problem
Auxiliary power units on aircraft consume excessive fuel when operating at intermediate power levels due to fixed rotation speed, leading to inefficient energy production and potential turbine damage during sudden load peaks.
Innovation Solution
A variable-speed gas turbine auxiliary power unit with energy storage and power management systems to regulate turbine speed and manage power transients, allowing for optimized fuel consumption and protection against sudden demand increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the gas turbine operates at constant nominal speed, then the electrical frequency remains stable, but fuel consumption increases at intermediate power levels
Solution Approach 1:
The patent implements variable speed operation of the gas turbine, allowing it to operate at different rotation speeds (e.g., 50%, 75%, 100% of nominal speed) depending on the power demand. This dynamic operation enables the turbine to optimize fuel consumption at each power level while the energy storage system compensates for frequency variations, thus resolving the contradiction between energy efficiency and operational simplicity
Solution Approach 2:
The energy storage system acts as an intermediary between the variable-speed gas turbine and the electrical network. It absorbs or releases energy to compensate for frequency deviations caused by variable turbine speed, thereby maintaining stable electrical frequency output while allowing the turbine to operate at fuel-efficient variable speeds
2Power
If the gas turbine accelerates quickly to meet sudden load peaks, then power demand is met, but the turbine may exceed surge margin or temperature limits
Solution Approach 1:
The energy storage system is pre-charged during normal operation to store available energy. When sudden load peaks occur, this pre-stored energy is immediately released to meet the power demand, allowing the turbine to accelerate more gradually and safely without exceeding surge margin or temperature limits, thus preventing turbine damage while still meeting power requirements
Solution Approach 2:
The energy storage system provides a cushion of available energy that absorbs the initial shock of sudden load peaks. This cushioning effect prevents direct transmission of abrupt power demands to the turbine, protecting it from dangerous acceleration rates and allowing controlled, safe operation while still responding to power needs
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 fuel consumption by up to 20% at intermediate power levels and prevents turbine damage during load peaks by using stored energy to smooth acceleration, enhancing overall energy efficiency and reliability.
Implementation Method 1
a gas turbine and an electricity generator mechanically connected to an outlet shaft of the gas turbine
Implementation Method 2
hot gas is not mechanically linked to the second spool
Implementation Method 3
an electricity generator mechanically connected to an outlet shaft of the gas turbine
Implementation Method 4
energy storage means... enabling power transients between two speeds of rotation of the turbine to be covered
Data Source
AI summary
A unit (1′, 10′, 100′) for generating non-propulsive electrical power for use on board an aircraft, the unit (1′, 10′, 100′) comprising an electricity production device (3, 30) comprising a gas turbine (31) and an electricity generator (32) mechanically connected to an outlet shaft (33) of the gas turbine (31), said electricity generator (32) including output electrical connections (320) for being electrically connected to an electrical power supply network (2, 20, 200) on board an aircraft.The unit (1′, 10′, 100′) includes energy storage means (5) and regulator means (6) configured to control the speed of rotation of the gas turbine (31) as a function of the electrical power required by the on-board electrical power supply network (2, 20, 200).