Perforated Windband Structure for Crosswind Pressure Balancing
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Solution Overview
Problem
Upblast fans used for exhaust gas dilution often generate significant noise and can create pressure differentials that lead to vortex formation, reducing air induction and dilution efficiency, particularly under windy conditions.
Innovation Solution
A windband with an elongate housing, perforated air inducer, and discharge sleeve is designed to minimize pressure differentials by inducing ambient air and reducing noise through acoustic materials and fin structures, enhancing the dilution of noxious gases while maintaining air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic silencers are mounted on or incorporated within the nozzle of an upblast fan to reduce noise, then noise levels are reduced, but back pressure or vortex phenomenon is created under certain conditions
Solution Approach 1:
The windband housing is divided into multiple sections with internal baffle structures that segment the exhaust flow path. This segmentation allows noise reduction through distributed acoustic treatment while maintaining pressure balance by creating multiple flow paths that prevent vortex formation.
Solution Approach 2:
Acoustic silencing materials are introduced as intermediary elements within the windband housing to absorb and dissipate noise energy from the exhaust jet, reducing noise propagation while the housing structure itself acts as a pressure-balancing intermediary to prevent back pressure buildup.
2Quantity of substance
If wind blows against the side of a stack or windband, then ambient air downstream exhibits low pressure phenomenon creating vortex, but this reduces air induction and dilution efficiency
Solution Approach 1:
The windband housing creates a pressure-equalizing structure that balances the low pressure differential between upstream and downstream sides during crosswind conditions. The elongated housing design with specific opening configurations maintains equipotential pressure distribution, preventing vortex formation and ensuring continuous ambient air induction.
Solution Approach 2:
The invention transitions from a simple vertical stack to an elongated horizontal windband structure that extends perpendicular to the exhaust jet. This dimensional change allows the structure to span across potential vortex paths, using its length to equalize pressure differentials and maintain stable air induction regardless of wind direction.
3Productivity
If tall exhaust stacks are used to deliver exhaust gases at higher altitude for dilution, then gas dilution efficiency is improved, but device complexity and space requirements increase
Solution Approach 1:
The invention merges the exhaust nozzle, windband housing, and acoustic silencing functions into a single integrated upblast fan assembly. This combination eliminates the need for separate tall stacks by using the fan's own housing as the windband structure, reducing device complexity while maintaining dilution efficiency through high-velocity jet injection.
Solution Approach 2:
The invention changes the operational parameters by using high-velocity exhaust injection at ground level rather than passive gravitational rise through tall stacks. The upblast fan creates sufficient jet velocity to achieve the same dilution effect as tall stacks, but through active kinetic energy injection rather than passive structural elevation.
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 noise and pressure differentials, minimizing vortex formation and ensuring efficient air induction and dilution of exhaust gases, even under windy conditions, thereby reducing the risk of noxious gases being drawn back to ground level.
Implementation Method 1
assisting in the minimization of a pressure differential between an upwind side of said windband and a downwind side of said windband
Implementation Method 2
A windband with an elongate housing, perforated air inducer, and discharge sleeve is designed to minimize pressure differentials by inducing ambient air and reducing noise through acoustic materials
Implementation Method 3
provide a high velocity jet of gas that is expelled upwardly into the atmosphere. The significant velocity of the gas permits it to achieve a sufficient altitude to provide for a dilution of the gas with ambient air
Implementation Method 4
a wind band is utilized to inject or entrain atmospheric air within the high velocity jet of exhaust gas to further mix ambient air with the exhaust, and to dilute the effects of any noxious components
Data Source
AI summary
A windband for an exhaust fan system. The windband comprises an elongate housing receivable about a exit nozzle of the exhaust fan system, an air inducer formed from a perforated material and positioned adjacent the bottom portion of the elongate housing, and a discharge sleeve positioned adjacent and secured to the top portion of the elongate housing. The discharge sleeve is formed from a perforated material and forms a passageway through which gas from the nozzle and induced ambient air passing through the elongate housing are discharged. The perforated air inducer and discharge sleeve together assist in the minimization of a pressure differential between an upwind side of the windband and a downwind side of the windband when the windband is subjected to wind striking the windband at an angle.