Ventilation Device Airflow Opening Porous Material Noise Reduction
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Solution Overview
Problem
Ventilation systems in buildings generate disturbing noise due to airflow through ventilation devices, limiting the maximum pressure drop that can be achieved without exceeding recommended sound effect levels, which restricts airflow and increases energy consumption.
Innovation Solution
Incorporating an air-permeable material in the airflow opening of ventilation devices to reduce noise generation and turbulence, allowing for higher pressure throttling while maintaining desired ventilation properties, by affecting the airflow velocity profile and covering a portion of the airflow opening to achieve effective sound attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pressure drop over the ventilation device is increased to achieve specified airflow through devices closer to the fan, then the ventilation effectiveness is improved, but the sound effect level exceeds recommended maximum values
Solution Approach 1:
The patent applies a porous sound-absorbing material arranged in the airflow opening of the ventilation device. This material allows airflow to pass through while absorbing sound waves generated by the air flow, thereby reducing the sound effect level. The porous structure provides multiple pathways for air molecules to traverse, dissipating acoustic energy through friction and conversion to heat, thus enabling higher pressure drops without exceeding sound thresholds.
Solution Approach 2:
The sound-absorbing material acts as an intermediary element between the airflow and the surrounding environment. It mediates the interaction by allowing air to pass through while simultaneously absorbing the harmful sound effects generated during airflow, thus protecting the environment from excessive noise while maintaining ventilation functionality.
2Stress or pressure
If the airflow opening size is reduced to throttle pressure and achieve desired airflow, then the pressure distribution is optimized, but the sound generation increases due to turbulence
Solution Approach 1:
The porous material in the airflow opening transforms the sharp pressure throttling effect into a more gradual pressure reduction across the porous structure. This distributes the pressure drop across multiple small pathways rather than a single restricted opening, reducing turbulence and associated sound generation while achieving the desired pressure distribution.
Solution Approach 2:
The patent converts the harmful effect of turbulence-induced sound into a beneficial outcome by using the porous material to create controlled, laminar-like flow patterns. The material transforms the chaotic turbulent flow that generates noise into a more orderly flow through its porous structure, thereby converting the harmful turbulence into a beneficial low-noise flow regime while maintaining pressure control.
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 air-permeable material significantly reduces noise generation and turbulence, enabling higher pressure throttling without exceeding sound threshold values, thus optimizing ventilation systems for effective airflow and reduced energy consumption.
Implementation Method 1
an air-permeable material is arranged in the airflow opening... to reduce noise generation and turbulence... achieving effective sound attenuation
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A ventilation device 21 configured to be connected to a mouth of a ventilation duct 9 between the ventilation duct and an outside space. The ventilation device comprises an airflow opening 27 for passage of an airflow 30 between the ventilation device and the outside space. An air-permeable material 29 is arranged in the airflow opening 27.