HVAC Door Gap Protrusions for Airflow Noise Reduction
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Solution Overview
Problem
HVAC systems generate undesirable noise due to high-speed laminar air flow through gaps between doors and housing walls, leading to whistles or hisses during operation.
Innovation Solution
Incorporating a noise-reducing feature with protrusions on the housing wall to break up air flow structures, inducing turbulent flow and reducing air vibration and noise, which can be achieved by arranging protrusions of specific shapes and sizes on the wall to disrupt smooth air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a door is positioned in a partially open position to allow air flow through the HVAC system, then air flow is enabled, but high-speed laminar flow through the gap generates undesirable noise
Solution Approach 1:
The noise-reducing feature segments the air flow structure by introducing protrusions that divide the continuous laminar flow into multiple smaller flow paths, disrupting the formation of coherent vortices that generate noise while still allowing air to pass through the gap
Solution Approach 2:
The protrusions change the flow parameters by transitioning the air flow from laminar to turbulent regime, which dissipates energy more effectively and reduces the coherent structures that produce audible noise, achieving noise reduction of up to 10 decibels
2Object-generated harmful factors
If the gap between the door and housing wall is reduced to minimize noise, then noise is reduced, but air flow restriction increases
Solution Approach 1:
The noise-reducing feature introduces a third dimension by adding protrusions that extend into the gap space, creating a multi-level flow path that reduces noise-generating coherent structures while preserving the overall air flow capacity through the gap
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 solution effectively reduces audible noise by up to 10 decibels without interfering with the normal operation of the HVAC system, maintaining functionality and reducing unwanted sound frequencies.
Implementation Method 1
break up, into several smaller structures, an air flow structure formed when air flowing through the gap contacts an edge of the door, thereby reducing air vibration in the gap and reducing noise
Data Source
AI summary
A HVAC system includes a housing including at least one wall, an air flow path defined at least partially by the at least one wall, and a door disposed in the air flow path, where the door is configured to i) block a flow of air through the air flow path when the door is in at least one closed position, and ii) allow the flow of air through the air flow path when the door is in a position other than the at least one closed position. A gap is formed between the door and the at least one wall when the door is in the position other than the at least one closed position. The HVAC system further includes a noise-reducing feature defined on at least a portion of the at least one wall. The noise-reducing feature configured to break up, into several smaller structures, an air flow structure formed when air flowing through the gap contacts an end of the door, thereby reducing air vibration in the gap and reducing noise of the HVAC system during operation thereof.