Felt-Throttle Supply Air Device for Low-Noise Flow Control
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Solution Overview
Problem
Existing supply air devices face challenges in controlling air flow while minimizing sound generation and accommodating high and low air pressures, with traditional solutions often resulting in high sound levels due to turbulence and pressure differences.
Innovation Solution
A supply air device featuring a chamber with a permeable side wall and a throttle member that adjusts the exposure of a felt layer to control airflow, utilizing a nonwoven fiber felt and a metal wire net structure to reduce sound generation and maintain low sound levels even at high pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional damper or perforated plate is used to throttle air flow, then air flow control is achieved, but high sound levels are generated due to turbulence at the edges
Solution Approach 1:
The patent applies porous materials (felt) as the throttling element instead of solid dampers or perforated plates. The felt allows air to pass through its porous structure while minimizing turbulence and edge effects that generate sound. This resolves the contradiction by providing flow control through the inherent porosity of the material rather than through sharp edges or openings that create turbulent flow and noise.
Solution Approach 2:
The patent uses a composite structure combining felt (porous material) with a support framework (wire net or rigid support). This composite approach provides both the flow control functionality of the porous felt and the structural integrity needed to withstand high pressure differences, while the felt layer dampens turbulence and reduces sound generation compared to solid materials alone.
2Volume of moving object
If high pressure is used in the system to accommodate reduced duct dimensions, then space efficiency is improved, but sound generation and turbulence increase
Solution Approach 1:
The felt acts as a pressure-resistant porous medium that can withstand high pressure differences while maintaining laminar flow characteristics. The porous structure distributes the pressure drop across many small pathways rather than concentrating it at sharp edges, thereby reducing turbulence and sound generation even when operating at high pressures required for compact duct installations.
Solution Approach 2:
The patent changes the physical parameter of the throttling element from solid or perforated (with sharp edges) to porous (with gradual pore structures). This parameter change allows the system to operate at high pressures while maintaining low sound levels, as the porous structure transforms the pressure drop mechanism from turbulent edge flow to distributed porous flow.
3Object-generated harmful factors
If a felt layer is used to reduce sound generation, then sound levels are minimized, but manufacturing complexity and cost may increase
Solution Approach 1:
The felt is a relatively simple porous material that can be manufactured and installed without complex processes. It replaces expensive and complex active noise control systems or multi-layer acoustic treatments, providing cost-effective sound reduction. The felt can be cut and installed similarly to traditional duct materials, maintaining ease of manufacture and installation.
Solution Approach 2:
The felt layer is a simple, replaceable component that can be easily installed and replaced if needed. Compared to complex acoustic treatment systems or precision-engineered low-noise dampers, the felt provides an economical solution that prioritizes functionality and ease of replacement over long-term durability, aligning with the principle of using simple, affordable components for noise 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 device effectively controls airflow with minimal sound generation, maintaining acceptable sound levels up to 200 Pa and 120 l/s, while also providing a self-cleaning mechanism through unrestricted flow portions and a cost-effective, easy-to-manufacture design.
Implementation Method 1
a first portion of the side wall adjacent the first end of the tube comprises a layer of felt through which air is discharged
Implementation Method 2
the pressure drop is controlled by viscous dissipation in the micro-passages within the porous media
Implementation Method 3
capable of controlling an air flow with minimal generation of sound... maintaining acceptable sound levels up to 200 Pa
Implementation Method 4
a throttle member slidably connected to the first tube to change a degree of exposure of the side wall to control air flow
Data Source
Figure 1~2
Figure 3~4
Figure 5~11
AI summary
Supply Air device (1) for controlling supply air flow to a building space, comprising a chamber (2) having a supply air inlet (3) and an air outlet (4). A first tube (10) in the chamber is connected at an open first end (11) to the supply air inlet, wherein the first tube has a side wall (13) which is permeable to air. A throttle member (30) is slidably connected to the first tube to change a degree of exposure of the side wall to control air flow through said side wall to the outlet. The exposable side wall comprises a layer of felt (14) through which air is discharged.