Acoustics and aeraulics, related disciplines, form the basis of ITS human resources expertise: study / engineering for the design of soundproofing equipment (silencers and other sound attenuation devices).
- for Heating, Ventilation and Air Conditioning (HVAC) networks, in order to allow the control of sound environments (i.e. of acoustical comfort) of buildings, industrial or not, and constructions - including Public Access Buildings (PAB) - in particular with regard to noise from equipment such as those involved in an air conditioning installation, or such as a refrigeration unit, a heat pump
- for industrial installations with fluid(s) network(s): in relation to various production or transformation methods, with cooling systems for machines or processes, with the supply of combustion air and with the exhaust of exhaust gases from ovens, engines or turbines, for air condensers, for air coolers (and also for cooling towers) or for - last but not least - aeroacoustic wind tunnels
With respect to projects involving noise sources whose sound emissions are variable (in number, level and frequency), and for which the objectives can be very different (depending on the limits imposed at specified locations, sometimes: in application of regulations or technical constaints e.g. specifications), in terms of acoustics and aeraulics, ITS expertise responds in particular to the following issues, for all or part (i.e. for components, considered individually) of a network:
- prediction of the sound impact on the basis of the consideration of the sound power levels of each noise source, the sound propagation conditions inside the system, i.e. for each component: insertion loss, self-noise (linked to the flow of the transported fluid) and also taking account of any diversions; the output data are, as appropriate: a sound power level (ref. 1pW) or a sound pressure level (réf. 20 µPa) at one (or more) specified location(s)
- prediction of aerodynamic performance based on the consideration of the characteristics of each component; the output data are in general the total pressure loss, necessary for the selection of the energy source of the network e.g. fan (centrifugal or axial), compressor, surpressor, turbine or any other turbomachine
They thus are particularly important: elbows, straight lengths, section changes, outlets, filters: for all, one should not neglect the influence of temperature or that of the fluid speed.
But that's not all, far from it.
In the field of acoustics and aeraulics, in terms of study / engineering, the expertise of ITS also includes (and above all, because more rare ?) the tailor made sizing and design of soundproofing devices that silencers are.
Whatever their operating principle (dissipative, resonant, reactive), ITS can define their geometry, both for the front section (often: circular, square or rectangular) and the length as for the internal parts (if it comes to a silencer with splitters or with a peripheral lining: width of the airways and thickness of the absorbent lining, possibly covered with a surfacing or a membrane acting as a resonator for low frequency attenuation; if it comes to reactive silencers: diameter and lengths of non-perforated tubes used as quarter-wave resonators).
For baffle silencers, and for cylindrical silencers, with or without central pod (widely used in aeraulic networks in buildings and for industrial installations), ITS also studies and defines the acoustic characteristics of the material used for the lining taking into account imperatives linked to technical considerations varying from one project to another e.g. resistance to abrasion due to air flow and to effluents, behavior with temperature, sensitivity to pressure or to water vapor content (e.g. in case of humid air).
For such silencers studied by ITS in terms of acoustics and aeraulics, the calculation note prepared by ITS provides reliable and precise simulation results regarding performance: insertion loss, flow noise and total pressure loss, for which a prediction is made by ITS, are comparable to those with ISO 7235 Acoustics - Laboratory measurement procedures for silencers in ducts and terminal units.
It must be said that ITS has adopt a wide range of calculation tools and means, enriched over time:
- some calculation means and tools, developed by the human resources of ITS e.g. the software SILDIS Pack 1-8, inside which we find Module 1 prediction of the acoustic and aeraulic performance of silencers (cf. link here); they have been validated by numerous comparisons between simulations and measurements for ever more precise simulations, in contexts ever (more) extended and always more demanding in terms of technicality; these software are published and marketed by ITS, with possible applications in the building as in industry (including: for gases other than air and for networks of pressurized fluids)
- other calculation means and tools, for which licenses have been acquired from less specialized software publishers (from CFD, FEM, BEM), for which interfacing with output data from the SILDIS software (e.g. for surface admittance of multilayered acoustic structures, plane or curved: then used as input data for this other sotware) allows simulations, in a way that is ITS’ own, applicable to unusual (and very specific) geometries
In addition, ITS expertise in acoustics and aeraulics in terms of study / engineering is extended by the marketing of silencers which, in addition to their guaranteed performance, are distinguished by their manufacturing quality (choice of the best materials, application of demanding calculation codes, use of the best assembly techniques and protection against corrosion) and their durability.