Lobed Air Diffuser Inserts for Ceiling-Guided Jet Mixing
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Solution Overview
Problem
Existing air diffusion devices in fan coil units fail to effectively mix conditioned air with ambient air, leading to significant temperature differences that result in cold drafts due to the air jet's short range and rapid descent towards the ground, compromising user comfort.
Innovation Solution
The use of lobed inserts in the diffusion device increases the contact surface area between the air jet and ambient air, generating additional longitudinal vortices and utilizing the Coanda effect to direct the air jet towards the ceiling, thereby enhancing mixing and maintaining a satisfactory range without rapid descent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lobed inserts are added to increase mixing, then temperature homogeneity improves, but device complexity increases
Solution Approach 1:
The diffusion device is segmented into multiple functional components: a base grille structure and multiple lobed inserts positioned within the grille. Each insert comprises several lobes that segment the air flow into multiple streams, increasing the contact surface area between conditioned air and ambient air. This segmentation enables enhanced mixing and temperature homogeneity while maintaining a modular structure that limits overall device complexity.
Solution Approach 2:
The inserts feature curved or rounded lobe surfaces instead of sharp edges. This curvature promotes smoother air flow separation and enhances the generation of longitudinal vortices along the air jet. The rounded portions of the lobes create more effective flow induction and mixing compared to angular geometries, improving temperature homogeneity without requiring overly complex geometries.
2Temperature
If lobed inserts with rounded portions are used to generate vortices, then mixing is enhanced, but manufacturing complexity increases
Solution Approach 1:
The lobes incorporate rounded portions with specific radius of curvature that balance manufacturing feasibility with vortex generation effectiveness. These curved surfaces can be produced using standard molding or bending processes, avoiding the need for complex multi-step manufacturing. The rounded geometry naturally promotes longitudinal vortex formation and enhances mixing efficiency while remaining compatible with conventional manufacturing methods.
3Length of moving object
If deflectors are positioned to direct air jet towards ceiling, then Coanda effect is utilized increasing range, but device complexity increases
Solution Approach 1:
The diffuser structure is divided into a base grille and separate lobed inserts that can be independently positioned and adjusted. This segmentation allows the deflectors to be optimally positioned within the grille structure to direct air jets toward the ceiling, utilizing the Coanda effect to extend jet range. The modular design enables this directional control without requiring a completely redesigned complex structure.
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 solution reduces the temperature difference between the air jet and ambient air by approximately 20%, prevents the air from falling quickly, and ensures a longer range, improving user comfort by homogenizing air temperatures and preventing drafts.
Implementation Method 1
the shearing of the primary fluid by the corrugated trailing edge generates additional longitudinal vortices
Implementation Method 2
These two phenomena increase the mixing of the supply air with the ambient air
Implementation Method 3
the jet of air blown through the grille does not benefit from the Coanda effect which tends to press the jet of air against the ceiling and increases the range of the jet
Data Source
Figure 1
Figure 2~5
Figure 3~4
AI summary
Device (1) for diffusing a jet of air, comprising at least one insert, which comprises lobes for separating, into two differently oriented flows, a flow of air ejected through the diffusion device, these lobes delimiting a thin and wavy trailing edge. It further comprises at least two deflectors (8) arranged on either side of the insert (10), which between them define an orifice (O10) for the passage of the air jet around the insert and which guide the jet of air in a predetermined direction.