Aft Engine Boundary Layer Ingestion Fan
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Solution Overview
Problem
Conventional aircraft propulsion systems face inefficiencies due to drag, which is not adequately addressed by existing boundary layer ingestion systems that often result in nonuniform airflow and efficiency losses in turbofan jet engines.
Innovation Solution
The introduction of an aft engine configured as a boundary layer ingestion fan, mounted at the aircraft's aft end, which includes a fan with blades and a nacelle, and a structural support system extending from the fuselage to the nacelle, allowing for efficient ingestion and consumption of boundary layer air to reduce drag and enhance thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If boundary layer ingestion systems are used to route slow moving air into turbofan jet engines, then drag is reduced by reenergizing the boundary layer airflow, but the relatively slow moving flow with nonuniform velocity profile causes efficiency loss in the engines
Solution Approach 1:
The boundary layer flow is segmented into multiple streams using分流 vanes, which divide the slow moving nonuniform flow into separate channels. This allows different portions of the boundary layer to be processed independently, enabling more uniform distribution to the engine while maintaining drag reduction benefits.
Solution Approach 2:
A mixing section with mixing vanes is introduced as an intermediary between the boundary layer ingestion and the engine inlet. This mixing section redistributes the nonuniform velocity profile into a more uniform flow pattern, acting as a mediator that preserves both drag reduction and engine efficiency.
2Object-generated harmful factors
If boundary layer air is ingested into the engine, then the boundary layer is reenergized and drag is reduced downstream, but the nonuniform velocity profile of the ingested air minimizes or negates the drag reduction benefits
Solution Approach 1:
The boundary layer flow is pre-processed before entering the engine through a mixing section that uniformizes the velocity profile. This preliminary action of flow conditioning ensures that the air is properly prepared for efficient engine ingestion, maximizing net propulsive thrust while maintaining drag reduction.
Solution Approach 2:
The velocity distribution parameter of the boundary layer air is changed from nonuniform to uniform through the mixing section. This parameter transformation allows the air to maintain its drag-reducing properties while being suitable for efficient engine operation and maximizing propulsive thrust.
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 effectively reduces aircraft drag while maintaining engine efficiency by utilizing the aft engine to ingest and energize boundary layer air, thereby improving the net propulsive thrust of the aircraft.
Implementation Method 1
an aft engine configured as a boundary layer ingestion fan, mounted at the aircraft's aft end, which includes a fan with blades and a nacelle
Data Source
AI summary
A propulsion system for an aircraft is provided having an aft engine configured to be mounted to the aircraft at an aft end of the aircraft. The aft engine includes a fan rotatable about a central axis of the aft engine having a plurality of fan blades attached to a fan shaft. The aft engine also includes a nacelle encircling the plurality of fan blades and a structural support system for mounting the aft engine to the aircraft. The structural support system extends from the fuselage of the aircraft, through the fan shaft, and to the nacelle when the aft engine is mounted to the aircraft. The aft engine may increase a net thrust of the aircraft when mounted to the aircraft.