Abstract
Noise is becoming one of the problems in many industrial applications. In this paper the aerodynamic noise in air duct system that arises from air flow passing over a surface of turning vanes is investigated. Based on Proudman's formula using Lighthill's acoustic analogy broadband acoustic noise model can be predicted. To model the turbulent flow in an air duct k - e turbulent model is used and required constants are obtained experimentally in a low speed wind tunnel followed by noise measurement in the vicinity of deflected airfoil. Several designs are investigated: Inner airfoil in the duct elbow, center positioned air foil, outer positioned and the overall combination of all previous cases. It was found that in order to satisfy all noise requirements and regulation, which are becoming more strict nowadays, the acoustic analysis and design must be performed in most industrial systems since the noise levels arising from the operating industrial equipment may represent occupational and health hazard.
Highlights
The accurate prediction of aerodynamically generated noise in air duct systems is necessary for noise control in industrial ducts, such as HVAC systems or pipelines
Acoustics analysis is related to fluid dynamics
Based on Proudman’s analogy, the flow induced acoustic intensity can be expressed in terms of standard steady-state variables corresponding to the turbulent kinetic energy k, and dissipation rate ε, which are conventionally used in CFD
Summary
In this paper the aerodynamic noise in air duct system that arises from air flow passing over a surface of turning vanes is investigated. To model the turbulent flow in an air duct k – ε turbulent model is used and required constants are obtained experimentally in a low speed wind tunnel followed by noise measurement in the vicinity of deflected airfoil. Several designs are investigated: Inner airfoil in the duct elbow, center positioned air foil, outer positioned and the overall combination of all previous cases. It was found that in order to satisfy all noise requirements and regulation, which are becoming more strict nowadays, the acoustic analysis and design must be performed in most industrial systems since the noise levels arising from the operating industrial equipment may represent occupational and health hazard
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