Boundary Layer Bypass Ducting for Aircraft Drag Recovery
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Solution Overview
Problem
Conventional aircraft designs face challenges in efficiently utilizing boundary layer air due to the turbulent nature of the air at different speeds, leading to inefficient fan blade designs that either optimize at a single speed or provide mediocre performance across a range of speeds, thereby reducing engine efficiency.
Innovation Solution
A drag recovery scheme using a boundary layer bypass duct system that routes boundary layer air around the engine and reintroduces it aft of the fan in a mixer-ejector scheme, increasing mass flow and reducing delta-V to achieve equivalent thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If engines are positioned far away from the blended wing body using large heavy pillars, then engine placement is achieved, but boundary layer air cannot be received and drag increases
Solution Approach 1:
The invention extracts the boundary layer air from the blended wing body surface using separate intake ducts positioned away from the engine, allowing the engine to be placed far from the body without losing access to boundary layer air. The heavy pillars are eliminated entirely, replacing them with a distributed duct system that collects boundary layer air from multiple locations along the wing body.
Solution Approach 2:
The invention introduces boundary layer intake ducts as intermediary components that mediate between the blended wing body surface and the engine. These ducts capture boundary layer air at locations远离the engine and transport it to the engine intake, enabling the engine to receive beneficial boundary layer air even when positioned far from the body on lightweight pylons.
2Productivity
If fan blade designs optimize for a single speed, then performance at that speed is maximized, but performance across a range of speeds becomes mediocre
Solution Approach 1:
The invention implements a dynamic boundary layer ingestion system where the intake ducts and flow management components can adapt to different flight conditions. The system dynamically adjusts the amount and characteristics of boundary layer air ingested based on flight speed, allowing fan blade designs to maintain high efficiency across a broader speed range rather than being optimized for a single operating point.
3Loss of energy
If boundary layer air is routed around the engine intake and reintroduced aft of the fan using a bypass duct system, then mass flow increases and drag is reduced, but system complexity increases
Solution Approach 1:
The invention segments the boundary layer air intake and bypass system into multiple distributed ducts along the blended wing body rather than using a single complex duct. This segmentation allows each duct to be relatively simple in design while collectively achieving the desired mass flow increase and drag reduction when all ducts work together in the bypass arrangement aft of the fan.
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 system enhances engine efficiency by utilizing boundary layer air effectively, reducing drag and increasing thrust, particularly at higher flight speeds, without causing vibration or noise penalties.
Implementation Method 1
boundary layer air from a top surface of the blended wing body
Implementation Method 2
Mixer-ejectors mix the boundary layer flow to increase mass flow
Implementation Method 3
a nozzle configured to direct the boundary layer air and the fan exhaust out of a nozzle exit
Data Source
AI summary
Technologies are described herein for a drag recovery scheme using a boundary layer bypass duct system. In some examples, boundary layer air is routed around the intake of one or more of the engines and reintroduced aft of the engine fan in the nozzle duct in a mixer-ejector scheme. Mixer-ejectors mix the boundary layer flow to increase mass flow.