Three-Engine Aircraft Power Plant Regulation
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Solution Overview
Problem
Regulating the power distribution among main and secondary engines in a three-engined rotary wing aircraft power plant is complex, especially in optimizing power delivery to the main rotor, leading to instability and increased wear on engines.
Innovation Solution
A method that determines specific setpoints for the frequency and power of each engine group, with the main engines operating on a first setpoint for rotor frequency and the secondary engine operating on a second setpoint only when necessary, using proportional integral regulation to manage power distribution dynamically based on flight conditions and needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If proportional integral regulation is used to control the frequency of rotation of the main rotor, then the frequency can be controlled accurately, but the complexity of connections between engine computers increases
Solution Approach 1:
The patent divides the three engines into two distinct groups: a first group of two main engines (E1, E2) and a second group of one secondary engine (E3). Each group has its own dedicated regulator device (first regulator 15 for main engines, second regulator 25 for secondary engine). This segmentation allows independent control strategies for each group, reducing the complexity of inter-engine computer connections while maintaining accurate frequency control through the proportional integral regulation applied to each group separately.
2Reliability
If three identical engines are used in the power plant, then the power plant can respond reactively to engine failure, but the regulation of power distribution becomes more complex
Solution Approach 1:
The patent applies different operational roles and control characteristics to different engines within the three-engine configuration. The two main engines (E1, E2) are regulated by the first regulator device on a first setpoint for frequency of rotation, while the secondary engine (E3) is regulated by the second regulator device on a second setpoint for power delivery. This local differentiation in control strategy simplifies the overall power distribution regulation complexity while maintaining the reliability benefit of having three identical engines for reactive response to failures.
3Reliability
If secondary engines operate continuously to provide backup power, then reliability is improved, but wear on secondary engines increases
Solution Approach 1:
The patent implements dynamic operation of the secondary engines based on real-time power requirements. The second regulator device controls the secondary engine(s) to operate only when the flight power required exceeds the maximum power available from the first group of main engines. This dynamic on-demand operation maintains reliability by ensuring backup power availability when needed, while minimizing wear and extending the service life of secondary engines by keeping them idle during normal operating conditions.
Data Source
AI summary
A power plant comprising two engine groups and a main power transmission gearbox. Each engine group drives the main gearbox mechanically in order to rotate a main rotor of an aircraft at a frequency of rotation NR. A first engine group comprising two main engines is regulated on a first setpoint NR* for the frequency of rotation NR, while a second engine group comprising a secondary engine is regulated on a second setpoint W2* for power. The second setpoint W2* for power is determined so that each secondary engine operates only when a flight power Wvol necessary for the flight of the aircraft is greater than the sum of the main maximum powers WMax1 from each main engine.