Distributed Propulsion Drivetrain for Boundary Layer Ingestion
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Solution Overview
Problem
The existing commercial aircraft configurations, such as the tube-and-wing design, have reached limitations in fuel efficiency improvements, and radical reconfigurations are not viable within the current air transportation infrastructure, necessitating a novel fuel-efficient aircraft configuration that integrates propulsion systems with the airframe to enhance fuel efficiency.
Innovation Solution
A mechanically-distributed propulsion system is integrated into the fuselage, allowing boundary layer ingestion, with a direction-reversing transmission and propulsor fans positioned at the aft end to convert mechanical drive power into thrust, reducing thrust requirements and weight, and optimizing fuel efficiency through a tightly integrated design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a new aircraft configuration is developed to improve fuel efficiency, then fuel efficiency is improved, but compatibility with existing air transportation infrastructure deteriorates
Solution Approach 1:
The propulsion system is segmented from the traditional engine-nacelle configuration and distributed along the fuselage. Multiple smaller propulsors are distributed along the fuselage length, allowing the system to achieve new aerodynamic efficiencies while maintaining a familiar overall aircraft configuration that is compatible with existing infrastructure.
Solution Approach 2:
The propulsors are integrated within the fuselage structure itself, with the propulsion system nested inside the airframe. This allows the new configuration to be housed within the existing fuselage envelope, maintaining external dimensional compatibility with current airport gates and hangars.
2Use of energy by moving object
If engine efficiency is improved through higher bypass ratios, then propulsion efficiency is improved, but nacelle drag and propulsor weight increase
Solution Approach 1:
Instead of one large high-bypass engine, the propulsion system is divided into multiple smaller distributed propulsors along the fuselage. Each propulsor operates at lower individual power levels, reducing the weight and drag penalties associated with large single engines while maintaining overall propulsion efficiency.
Solution Approach 2:
Each distributed propulsor is optimized for its local position on the fuselage, with blade designs and operating parameters tailored to the specific airflow conditions at each location. This local optimization allows efficient operation without the excessive weight of a single large engine.
3Use of energy by moving object
If a mechanically-distributed propulsion system is integrated into the fuselage, then fuel efficiency is improved through boundary layer ingestion, but system complexity increases
Solution Approach 1:
The propulsion system is merged with the fuselage structure, combining the airframe and propulsion functions into a single integrated design. The fuselage itself becomes part of the propulsion system by providing boundary layer flow to the propulsors, reducing the need for separate intake structures and simplifying the overall system.
Solution Approach 2:
The fuselage boundary layer flow automatically serves as the intake for the distributed propulsors. The aircraft's own motion through the air generates the boundary layer that feeds the propulsors, eliminating the need for separate air intake systems and reducing mechanical complexity.
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 achieves a 71% reduction in fuel burn, 60 dB reduction in noise, and 87% reduction in low-temperature oxidation NOx, while maintaining compatibility with existing infrastructure and materials, and improving aerodynamic efficiency by integrating propulsion systems with the airframe.
Implementation Method 1
a propulsor fan coupled to the second rotating shaft to convert the mechanical drive power into thrust
Implementation Method 2
the direction-reversing transmission is configured to redirect the mechanical drive power received at the first rotating shaft from a first direction to face a second direction at the second rotating shaft
Implementation Method 3
integrating a propulsion system into the fuselage in a way that enables ingestion of the aircraft boundary layer to provide a fuel efficiency benefit
Data Source
AI summary
An aircraft with an integrated boundary layer ingesting propulsion having a mechanically-distributed propulsion system. The mechanically-distributed propulsion system may include an engine to generate a mechanical drive power, a drive shaft, a direction-reversing transmission, and a propulsor fan. The drive shaft may be operatively coupled to the engine to receive the mechanical drive power. The direction-reversing transmission may have a first rotating shaft and a second rotating shaft, the first rotating shaft operatively coupled to the drive shaft to receive the mechanical drive power, which is configured to redirect the mechanical drive power received at the first rotating shaft from a first direction to face a second direction at the second rotating shaft. The propulsor fan may be coupled to the second rotating shaft to convert the mechanical drive power into thrust.