Hybrid Rotorcraft Power Split for One-Engine-Inoperative Capability
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Solution Overview
Problem
Traditional helicopter power systems using two gas turbine engines are inefficient and heavy, requiring larger engines to meet one-engine-inoperative power requirements, which increases weight, fuel consumption, and maintenance costs.
Innovation Solution
A hybrid electric system for rotorcraft that includes two thermal engines and an electrical machine, where the thermal engines are sized below the one-engine-inoperative power requirement, and the electrical machine provides the remaining power needed to meet safety regulations, allowing for smaller, lighter engines and reduced maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two gas turbine engines are sized to meet one-engine-inoperative power requirements, then safety requirements are satisfied, but engine weight and fuel consumption increase
Solution Approach 1:
The patent replaces the mechanical power delivery system with a hybrid electric architecture. Instead of relying on oversized mechanical engines to meet OEI requirements, the system uses two smaller engines coupled with an electrical machine (generator/motor) and energy storage device. The electrical machine can rapidly deliver or absorb power to compensate for engine failure, allowing the thermal engines to be sized for normal operation rather than emergency contingencies.
Solution Approach 2:
The patent changes the power delivery parameters by introducing an electrical interface between the engines and the load. The electrical machine acts as a buffer that can instantly provide or absorb power, changing the temporal and quantitative characteristics of power delivery. This allows the thermal engines to operate at optimal parameters continuously rather than being oversized for peak emergency demands.
2Reliability
If two gas turbine engines are sized to meet one-engine-inoperative power requirements, then safety requirements are satisfied, but fuel consumption increases
Solution Approach 1:
The electrical power transmission system replaces the direct mechanical coupling, enabling more efficient power management. The electrical machine can precisely control power flow and rapidly respond to power demands without the inefficiencies of mechanical torque transmission, reducing overall energy consumption while maintaining safety capabilities.
Solution Approach 2:
By changing to electrical power delivery, the system optimizes energy parameters. The electrical machine minimizes power losses during transmission and allows the thermal engines to operate at more efficient operating points, reducing fuel consumption while maintaining the ability to meet OEI power requirements through electrical power supplementation.
3Power
If larger engines are used to meet one-engine-inoperative requirements, then power availability is improved, but maintenance costs increase
Solution Approach 1:
The patent segments the power delivery function into multiple independent components: two smaller thermal engines, an electrical machine, and an energy storage device. This segmentation allows each component to be optimized for its specific function and sized appropriately, rather than requiring one or two oversized engines. Smaller, specialized components are generally more efficient and require less intensive maintenance than larger, multi-functional engines.
Solution Approach 2:
Replacing the purely mechanical engine system with a hybrid electric system reduces maintenance requirements. Electrical machines and power electronics generally have fewer moving parts and lower maintenance needs compared to large mechanical engines. The system trades complex electrical systems for reduced mechanical complexity, overall reducing maintenance burden.
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
The hybrid electric system reduces weight, fuel consumption, and maintenance costs while providing improved performance and efficiency, enabling safer and more efficient rotorcraft operations.
Implementation Method 1
an electrical machine (e.g., useable as a motor and a generator)
Implementation Method 2
a first thermal engine (103a), a second thermal engine (103b)
Data Source
Figure 1
Figure 2
AI summary
A hybrid electric system for a rotorcraft can include a first thermal engine (103a), a second thermal engine (103b), and an electrical machine (105). The first thermal engine (103a) can be sized to produce a maximum first thermal engine power that is below a one-or-more-engine-inoperative (OEI) requirement power and the second thermal engine (103b) can be sized to produce a maximum second thermal engine power that is below the OEI requirement power. The electrical machine (105) can be sized to provide at least a remaining power needed to reach the OEI requirement power in an OEI state.