HVAC Door Gap Noise Reduction Using Protrusions for Turbulent Flow
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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 above or below the door, which breaks up the air flow structure into smaller structures, inducing turbulent flow and reducing air vibration and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a door is positioned in a partially open position to allow air flow, then air flow control is achieved, but high-speed laminar flow through the gap generates undesirable noise
Solution Approach 1:
The patent introduces a noise-reducing feature as an intermediary element positioned in the air flow path between the door and housing wall. This feature disrupts the laminar flow structure and converts it to turbulent flow, which reduces the generation of whistle and hiss noises while still allowing air to pass through the gap when the door is in a partially open position.
2Object-generated harmful factors
If the door is in a closed position to block air flow, then noise is reduced, but air flow control functionality is compromised
Solution Approach 1:
The noise-reducing feature is applied locally at the gap region between the door and housing wall, rather than modifying the entire door or housing structure. This localized intervention selectively addresses the noise problem in the air flow path while preserving the overall door functionality and air flow control capabilities when the door is closed or open.
3Object-generated harmful factors
If protrusions are added to break up air flow structure, then noise is reduced by up to 10 decibels, but device complexity increases
Solution Approach 1:
The noise-reducing feature is segmented into multiple protrusions that are distributed across the surface. These protrusions work collectively to break up the laminar flow into turbulent flow, achieving noise reduction of up to 10 decibels. The segmented structure is simpler than alternative solutions such as acoustic liners or active noise control systems.
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 noise reduction achieved is up to 10 decibels, maintaining normal system operations without interfering with door functionality or internal parts.
Implementation Method 1
substantially laminar high speed flow of the air travels through a gap
Implementation Method 2
breaks 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
Data Source
Figure 1A~3
Figure 4A~4H
Figure 5A~5B
AI summary
A HVAC system includes a housing (12) including at least one wall (14), an air flow path (18) defined at least partially by the at least one wall (14), and a door (20) 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 (24) 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 (28) 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.