Ducted Fan Vortex Generator Lip Flow Control
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Solution Overview
Problem
Existing ducted fan technologies face challenges in efficiently generating thrust and controlling air separation at the lip portion of the duct, particularly during transitions and in crosswind conditions.
Innovation Solution
The ducted fan device features a plurality of fan devices with cylindrical smaller and larger ducts, where each fan is arranged on the inner side of the larger duct, and at least a part of the smaller duct is positioned outside the larger duct on the upstream side in the airflow direction. This configuration utilizes the Coanda effect and ejector effect to enhance airflow and thrust generation while controlling air separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If air flows into the duct at an angle to the axis during transition mode or crosswind, then the ducted fan can operate in various flight conditions, but air separation occurs at the lip portion reducing thrust efficiency
Solution Approach 1:
A vortex generator is introduced as an intermediary element at the lip portion of the duct. This vortex generator creates controlled vortices that act as a mediator between the angled incoming airflow and the duct interior, preventing flow separation while maintaining adaptability to various flight conditions including transition mode and crosswind operations
Solution Approach 2:
The invention changes the flow parameters by generating controlled vortices through the vortex generator. This alters the airflow characteristics at the lip portion, transforming the separated flow into a attached flow regime that maintains thrust efficiency across different flight conditions
2Device complexity
If conventional ducted fan configurations are used, then the structure is simple, but thrust generation efficiency is insufficient
Solution Approach 1:
Instead of redesigning the entire duct structure, the invention applies a localized modification at the lip portion using a vortex generator. This local quality change focuses the complexity only where needed (at the lip) to improve overall thrust generation efficiency while maintaining structural simplicity elsewhere
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 improves thrust generation, reduces noise, and enhances control over air separation at the lip portion of the duct, leading to improved performance in various flight conditions, including transitions and crosswinds.
Implementation Method 1
a vortex generator 34 extending in a radial direction from the inner circumferential surface of the duct 30. The vortex generator 34 generates a vortex in an airflow introduced into the duct 30
Implementation Method 2
the end face on the downstream side in the flow direction of every smaller duct is located downstream in the flow direction with respect to an end face on the upstream side in the flow direction of the larger duct
Data Source
AI summary
A ducted fan device includes: a plurality of fan devices each having a fan configured to be rotated about a first axis to generate an airflow and a cylindrical smaller duct surrounding the fan about the first axis and extending in a first axis direction; and a cylindrical larger duct extending in a second axis direction parallel to the first axis. Each of the fan devices is arranged on an inner side of the larger duct when viewed in the second axis direction. At least a part of the smaller duct is arranged outside the larger duct on an upstream side in a flow direction of an airflow when viewed in a direction orthogonal to the second axis.