This paper examines the performance of a large new multi storey building which relies exclusively on natural ventilation. The building is designed to provide the main library and associated functions for Coventry University. The research outlines the sophisticated control systems necessary for such a building and provides an analysis of the strategies and techniques required for its implementation. A case study of user satisfaction demonstrates that a large naturally ventilated building can provide a pleasant comfortable environment for occupants.
This paper deals with techniques aiming at reducing noise entering into naturally ventilated buildings while reducing airflow path resistance.The description of the combined experimental and theoretical approach is made. A method is suggested to enable the acoustic and airflow performance of apertures for natural ventilation systems to be designed simultaneously.
Microperforated sound absorbers have been successfully implemented in suspended ceilings, transparent panel absorbers or other applications. That principle of microperforation has been introduced to further engineering areas such as duct systems where the air flows through the micorperforation. So along with the ventilation aspects, the sound absorption effects need to be taken into account. In that aim, the theory of a microperforated absorber was extended by the effects due to airflow through the microperforation.
New equations derived from the recent ASHRAE-sponsored research project RP-1026 will enable HVAC system designers to better predict aero-acoustic performance of sheet metal plenums. This paper deals primarily with the aerodynamic performance of flow-through plenums and presents new
total pressure drop equations for some of the most common plenum configurations. Comparisons are made between these equations, computational fluid dynamics (CFD) analyses, and hand-calculation methods. The practical uses of plenums are discussed along with prescriptive rules of thumb to help
The analytical model described in the first part of the paper is partially validated here by comparing the theoretical results to experimental data collected in a series of model test experiments in an open-jet anechoic wind tunnel. The emphasis is on the validation of the trailing-edge noise model. A comparison is made with existing numerical computations in the literature. The transfer function is found to be roughly invariant with respect to flow conditions encountered on an isolated airfoil. Furthermore, a first application of the model to a cooling fan is presented.
This paper, the first of 2 parts, is dedicated to the analytical modeling of the broadband noise radiated by subsonic fans, such as encountered in HVAC or engine cooling applications. A fan noise prediction scheme is proposed on the basis of single-airfoil linearised unsteady aerodynamics theories. Spanwise distributed sources only are investigated, corresponding to three basic mechanisms, namely the noise from impingement of upstream turbulence, the trailing edge noise associated with turbulent boundary layer scattering, and vortex shedding noise.
This paper is a description of the design process of a new generation low noise axial fan. The emphasis is on the practical use of acoustic knowledge issued from published work and engineer know-how. The use of date issued from numerical simulation is also presented.
This paper presents a comparison of the predicted and measured acoustic system effect induced by a box with a lateral opening at the inlet of an axial flow fan. The objective of this study carried out on an academic configuration, is to develop and validate prediction models for real cases.
Noise measurements were made at 10 locations in ‘canyon’ streets in Athens with aspect ratio (height/width) varying from 3:1 to 1:1. The main purpose of the measurements was to examine the vertical variation in noise in the canyons to indicate the natural