Slotted Fan Blade Design for Airflow Separation

Solution Overview

Problem

Conventional fan blade designs require higher angles of incidence to achieve significant air movement, leading to inefficiencies and increased airflow separation, whereas the goal is to enhance air movement at reduced angles of incidence.

Innovation Solution

A novel fan blade design featuring a primary airfoil with a longer chord and a secondary smaller chord airfoil in a slotted configuration, with a twist along the span to optimize angle of incidence, minimizing airflow separation and increasing downward air movement by creating a higher pressure differential between the upper and lower surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional fan blade designs use higher angles of incidence to achieve significant air movement, then air movement is improved, but airflow separation increases and efficiency decreases

Engineering Contradiction:

Improveair movementVSAvoidairflow separation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The fan blade is divided into multiple airfoil elements (primary airfoil and secondary airfoils) arranged in a stacked configuration. This segmentation allows each airfoil element to operate at optimized local angles of incidence, generating effective air movement while reducing overall airflow separation compared to a single conventional blade operating at high incidence angles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a conventional two-dimensional airfoil section to a three-dimensional stacked airfoil configuration. Multiple airfoil elements are arranged vertically with spacing between them, creating a multi-layered structure that enhances air movement capability while maintaining lower individual incidence angles, thereby reducing airflow separation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If conventional fan blade designs use higher angles of incidence to achieve significant air movement, then air movement is improved, but efficiency decreases

Engineering Contradiction:

Improveair movementVSAvoidefficiency

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The fan blade is divided into multiple airfoil elements (primary airfoil and secondary airfoils) arranged in a stacked configuration. This segmentation allows each airfoil element to operate at optimized local angles of incidence, generating effective air movement while reducing overall airflow separation compared to a single conventional blade operating at high incidence angles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a conventional two-dimensional airfoil section to a three-dimensional stacked airfoil configuration. Multiple airfoil elements are arranged vertically with spacing between them, creating a multi-layered structure that enhances air movement capability while maintaining lower individual incidence angles, thereby reducing airflow separation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If a single airfoil design is used, then structural simplicity is maintained, but air movement performance is limited

Engineering Contradiction:

Improveair movementVSAvoidblade structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The fan blade is divided into multiple airfoil elements (primary airfoil and secondary airfoils) arranged in a stacked configuration. This segmentation allows each airfoil element to operate at optimized local angles of incidence, generating effective air movement while reducing overall airflow separation compared to a single conventional blade operating at high incidence angles.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple airfoil elements are merged into a single integrated blade structure through vertical stacking with controlled spacing. This combination creates a multi-element airfoil system that achieves enhanced air movement performance while maintaining structural integrity as a unified blade assembly.

Inventive Principle:

Principle #5Merging (Combining)

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 design achieves a 31% increase in airflow at a reduced angle of incidence, producing faster and thicker downdrafts with improved performance compared to traditional flat blade designs, as demonstrated by 2D and 3D analyses.

Implementation Method 1

The air movement mechanism is based on increased pressure differential between the upper and lower surface of the primary airfoil which is based on increased camber and the addition of a secondary airfoil

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

The slotted configuration between the primary airfoil and secondary airfoil allows for higher pressure fluid from the lower surface of the primary airfoil to flow through the slot and re-energize the flow along the upper surface of the secondary airfoil, resulting in attached flow

Methodology Applied

Scientific EffectFlow re-energization: Venturi Effect

Data Source

PatentUS20240418089A1Fan blade design

Publication Date: 2024.12.19 BERMUDEZ ONOPA RAMON DAVID

AI summary

The novel fan blade functions by capturing the air mass via an upper, larger airfoil with a lower, smaller chord airfoil arrangement that channels air through the slot between the larger and smaller airfoil that are both twisted along the span of the blade. This design generates air movement more effectively and achieves significantly better performance than a traditional fan blade design.