Abstract
In recent years, several studies have sought to develop a generalised prediction method for flow-generated noise that is produced by the interaction of multiple elements in the airflow duct of an air-conditioning system. The prediction methods for single or multiple in-duct discontinuities are based on the assumption that there is a constant of proportionality between the fluctuating drag force and the steady drag force that acts on the flow spoilers. To develop a prediction method for multiple in-duct discontinuities, the concept of partially coherent sound fields is adopted to formulate the sound powers that are produced by the interaction of multiple in-duct elements at frequencies both below and above the cut-on frequency of the lowest transverse duct mode. An interaction factor is defined as the result of a simple relationship between the sound power that is due to the interaction of multiple in-duct elements and the sound power that is due to a single in-duct element. The method has been found to agree well for two in-duct elements with experimental studies. This paper introduces the recent developments in the prediction methods, and discusses the problems that are encountered in the development of the technique.
Original language | English |
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Pages (from-to) | 23-26 |
Number of pages | 4 |
Journal | HKIE Transactions Hong Kong Institution of Engineers |
Volume | 12 |
Issue number | 4 |
DOIs | |
Publication status | Published - 1 Jan 2005 |
Keywords
- Air Duct
- Flow-generated Noise
- Generalised Prediction Method
- In-duct Elements
- Sound Power Level
ASJC Scopus subject areas
- General Engineering