Acoustics Research & Development (R&D)

ITS is active in acoustics Research and Development (R&D), with many contents produced by ITS human ressource.

Papers in relation to the acoustic properties of multilayered structures (planes or orthotropic partitions), made of plates and of porous media, play an important role here, with respect to their acoustic absorption as useful for reducing the reverberation of industrial or tertiary premises (acoustic correction) or for the reduction of noise by means of dissipative mufflers (e.g. for ventilation and air-conditioning systems, for the suction and discharge of fan, engine and turbo-machineries), or with respect to their acoustic absorption and their ability to limit sound transmission, which is sought for acoustic insulation panels (e.g. for machine enclosures, noise barriers and wall in industry, metal cladding in the construction or for claustras intended for offices or canteen).

Reports concerning research and development (R&D) works related to the acoustics and aerodynamics of fluid networks (under pressure when not conventional air systems) are numerous, both in terms of the performance of subsets such singularities such as ducts of different geometries, elbows, chimneys, nozzles, silencers of all kinds (which must be modeled for a correct consideration of their sound impact) as for the noise emitted by valves or gaseous jets including safety valves, and also for associated discharge parameters.

In addition, various documents deal with the propagation of sound, either outdoors (in relation to atmospheric absorption or to the presence of obstacles), or in premises (in relation to the phenomenon of reverberation) for problems related to noise decay (spatial or temporal).

ITS's research and development (R&D) works in acoustics (based on measurements and on simulations by the means of computation software with in-house programming), all related to the development of soundproofing products, devices and systems for building and industry, are the scientific background of ITS services offerings in the field of insulation and are illustrated by the contents produced, over time, by the human resource of ITS.

  • Report PhR09-000  Comparisons between measurements and predictions of the properties of dry air in terms of thermodynamics and fluid dynamics (2009)
  • Report PhR08-005  Review of the computation scheme of dissipative silencers (2008)
  • Report PhR16-006  Acoustic development program for ITS: aperiodic report of the implementation (2016)
  • Report PhR08-007  Comparisons between measurements and prediction with a 5-parameters model for the COmputation of Acoustic Layers (2008)
  • Report PhR16-008  User’s manual for the software SILDIS (2016)
  • Report PhR08-009  Overview of the properties of some materials in the context of the design of sound proofing equipments involving porous media (2008)
  • Report PhR14-011  Acoustic and aeraulic design of dissipative silencers: the status of the Art (2014)
  • Report PhR14-012  Comparisons between measurements and predictions of the transmission loss of a single-leaf (plane) partition consisting of a monolithic, isotropic plate (and related considerations) (2014)
  • Report PhR16-013  Sound Impact Limitation Design for Industrialized Solutions: a single Excel based software for a wide range of applications (presentation brochure for the software SILDIS) (2016)
  • Report PhR08-014  Procedure for the use of Excel based programs with a restricted access (2008)
  • Report PhRxx-015  Collection of soundproofing constructions systems: a companion to “User’s manual for the software SILDIS” (20xx)
  • Report PhR16-016  Comparisons between measurements and predictions of the sound absorption of a multilayered (plane) acoustic structure (2016)
  • Report PhR09-017  Comparisons between measurements and predictions of the sound transmission of a single-leaf (plane) partition consisting of a porous medium (2009)
  • Report PhR09-018  Comparisons between measurements and predictions of the sound transmission of a single-leaf (plane) partition consisting of a monolithic, orthotropic plate (2009)
  • Report PhR09-020  Comparisons between measurements and predictions of the sound transmission of  a (plane) partition consisting of a monolithic, isotropic plate covered by a porous medium (2009)
  • Report PhR09-023  Acoustic design of plane partitions: the status of the Art (2009)
  • Report PhR09-024  Comparisons between measurements and predictions of the sound transmission of a double-leaf (plane) partition consisting of 2 monolithic, isotropic plates (2009)
  • Report PhR09-025  Comparisons between measurements and predictions of the sound transmission of a double-leaf (plane) partition consisting of 1 monolithic, isotropic plate and 1 monolithic, orthotropic plate (2009)
  • Report PhR09-026  Comparisons between measurements and predictions of the sound transmission of a triple-leaf (plane) partition consisting of (3) monolithic, isotropic plates (2009)
  • Report PhR09-027  Comparisons between measurements and predictions of the sound transmission of a (plane) plate with an extensional damping (2009)
  • Report PhR09-030  Sécurisation du programme de calcul SILDIS  (2009)
  • Report PhR15-031  Comparisons between measurements and prediction of the acoustic performance of rectangular dissipative silencers. Part 1: propagation loss with or without flow (2015)
  • Report PhR09-032  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers. Part 2: bypass correction (2009)
  • Report PhR09-033  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers. Part 3: reflection loss (2009)
  • Report PhR09-034  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers. Part 4: insertion loss without self noise (2009)
  • Report PhR09-035  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers. Part 5: self noise (2009)
  • Report PhR13-037  Comparisons between measurements and predictions of the aeraulic performance of rectangular dissipative silencers.  (2013)
  • Report PhR13-041  Comparisons between measurements and prediction of the acoustic performance of square dissipative silencers. Part 1: propagation loss with or without flow (2013)
  • Report PhR09-047  Comparisons between measurements and predictions of the aeraulic performance of square dissipative silencers. (2009)
  • Report PhR09-051  Comparisons between measurements and prediction of the acoustic performance of round dissipative silencers. Part 1: propagation loss with or without flow (2009)
  • Report PhR09-055  Comparisons between measurements and predictions of the acoustic performance of round dissipative silencers. Part 5: self noise (2009)
  • Report PhR09-057  Comparisons between measurements and predictions of the aeraulic performance of round dissipative silencers. (2009)
  • Report PhR16-061  Comparisons between measurements and prediction of the acoustic performance of round dissipative silencers with a central pod. Part 1: propagation loss with or without flow (2016)
  • Report PhR17-065  Comparisons between measurements and prediction of the acoustic performance of round dissipative silencers with a central pod. Part 5: self noise (2017)
  • Report PhR17-067  Comparisons between measurements and predictions of the aeraulic performance of round dissipative silencers with a central pod (2017)
  • Report PhR09-071  Comparisons between measurements and prediction of the acoustic performance of resonant silencers made of Pine Tree splitters with a rear lining. Part 1: propagation loss with or without flow (2009)
  • Report PhR09-075  Comparisons between measurements and prediction of the acoustic performance of resonant silencers made of Pine Tree splitters with a rear lining. Part 5: self noise (2009)
  • Report PhR09-081  Comparisons between measurements and prediction of the acoustic performance of resonant silencers made of Pine Tree splitters with a lateral lining. Part 1: propagation loss with or without flow (2009)
  • Report PhR10-085  Comparisons between measurements and prediction of the acoustic performance of resonant silencers made of Pine Tree splitters with a lateral lining. Part 5: self noise (2010)
  • Report PhR13-090  Comparisons between measurements and predictions of the acoustic performance of rectangular duct wall. Part 1: break-out sound transmission loss (2013)
  • Report PhR11-091  Comparisons between measurements and predictions of the acoustic performance of circular duct wall.Part 1: break-out sound transmission loss (2011)
  • Report PhR13-094  Comparisons between measurements and predictions of the acoustic performance of round bends. Part 1: insertion loss without self noise (2013)
  • Report PhR13-095  Comparisons between measurements and predictions of the acoustic performance of round bends. Part 2: self noise (2013)
  • Report PhR13-096  Comparisons between measurements and predictions of the acoustic performance of round bends. Part 3: insertion loss with self noise (2013)
  • Report PhRxx-100  Comparisons between measurements and predictions of the acoustic performance of rectangular ducts wall. Part 2: sound power level radiated by (duct) wall (20xx)
  • Report PhRxx-101  Comparisons between measurements and predictions of the acoustic performance of circular ducts wall. Part 2: sound power level radiated by (duct) wall (20xx)
  • Report PhR15-104  Comparisons between measurements and predictions of the spatial decay of speech in open-plan offices (2015)
  • Report PhR15-105  Comparisons between measurements and predictions of the sound spatial decay in industrial spaces (2015)
  • Report PhR15-107  Comparisons between measurements and predictions of exhaust ducts directivity  (2015)
  • Report PhR15-108  Comparisons between measurements and predictions of sound attenuation during propagation in air (2015)
  • Report PhR16-111  Comparisons between measurements and predictions of control valves aerodynamic noise.Part 1: flow indicators (2016)
  • Report PhR16-112  Comparisons between measurements and predictions of control valves aerodynamic noise. Part 2: noise level (2016)
  • Report PhR13-115  Comparisons between measurements and predictions of the acoustic performance of rectangular bends. Part 2: self noise (2013)
  • Report PhR16-117  Comparisons between measurements and predictions of control valves aerodynamic noise  (2016)
  • Report PhRxx-121  Comparisons between measurements and prediction of the acoustic performance of conventional splitter silencers versus silencers with discontinued splitters. Part 1: propagation loss with or without flow (20xx)
  • Report PhRxx-122  Comparisons between measurements and prediction of the acoustic performance of conventional splitter silencers versus silencers with discontinued splitters. Part 2: bypass correction (20xx)
  • Report PhRxx-123  Comparisons between measurements and prediction of the acoustic performance of conventional splitter silencers versus silencers with discontinued splitters. Part 3: reflection loss (20xx)
  • Report PhRxx-124  Comparisons between measurements and prediction of the acoustic performance of conventional splitter silencers versus silencers with discontinued splitters. Part 4: insertion loss without self noise (20xx)
  • Report PhRxx-125  Comparisons between measurements and prediction of the acoustic performance of conventional splitter silencers versus silencers with discontinued splitters. Part 5: self noise (20xx)
  • Report PhR16-131  Comparisons between measurements and prediction of the acoustic performance of rectangular dissipative silencers with discontinued splitters. Part 1: propagation loss with or without flow (2016)
  • Report PhRxx-132  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers with discontinued splitters. Part 2: bypass correction (20xx)
  • Report PhRxx-133  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers with discontinued splitters. Part 3: reflection loss (20xx)
  • Report PhRxx-134  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers with discontinued splitters. Part 4: insertion loss without self noise (20xx)
  • Report PhR15-135  Comparisons between measurements and predictions of the acoustic performance of rectangular dissipative silencers with discontinued splitters. Part 5: self noise (2015)
  • Report PhR15-137  Comparisons between measurements and prediction of the aerodynamic performance of rectangular dissipative silencers with discontinued splitters (2015)
  • Report PhR16-139  On the comparison of the performance of silencers with continuous and discontinuous splitters: 2 case studies with the software SILDIS (2016)
  • Report PhR13-141  Comparisons between measurements and predictions of the acoustic performance of straight round ducts. Part 1: insertion loss without self noise (2013)
  • Report PhR13-142  Comparisons between measurements and predictions of the acoustic performance of straight round ducts. Part 2: self noise (2013)
  • Report PhR13-143  Comparisons between measurements and predictions of the acoustic performance of straight round ducts. Part 3: insertion loss with self noise (2013)
  • Report PhR13-151  Comparisons between measurements and predictions of the acoustic performance of straight rectangular ducts. Part 1: insertion loss without self noise (2013)
  • Report PhR13-152  Comparisons between measurements and predictions of the acoustic performance of straight rectangular ducts. Part 2: self noise (2013)
  • Report PhR13-153  Comparisons between measurements and predictions of the acoustic performance of straight rectangular ducts. Part 3: insertion loss with self noise (2013)
  • Report PhR13-161  Comparisons between measurements and predictions of nozzle reflection (2013)
  • Report PhR14-171  Comparisons between measurements and predictions of sound decay in enclosed spaces. Part 1: temporal sound decay after noise-off (2014)
  • Report PhR14-172  Comparisons between measurements and predictions of sound decay in enclosed spaces. Part 2: reverberation time (2014)
  • Report PhR17-173  Comparisons between measurements and predictions of sound decay in enclosed spaces. Part 3: spatial sound decay (2017)
  • Report PhR16-181  Comparisons between measurements and prediction of jet noise. Part 1: turbulence noise. Sub-part 1: acoustic efficiency (2016)
  • Report PhR16-182  Comparisons between measurements and prediction of jet noise. Part 1: turbulence noise. Sub-part 2: sound power  (2016)
  • Report PhR16-184  Comparisons between measurements and prediction of jet noise. Part 1: turbulence noise. Sub-part 4: spectrum (2016)
  • Report PhR16-191  Comparisons between measurements and prediction of jet noise. Part 2: chocked jet noise. Sub-part 1: acoustic efficiency (2016)
  • Report PhR16-192  Comparisons between measurements and prediction of jet noise. Part 2: chocked jet noise. Sub-part 2: sound power  (2016)
  • Report PhR16-193  Comparisons between measurements and prediction of jet noise. Part 2: chocked jet noise. Sub-part 3: peak frequency (2016)
  • Report PhR16-194  Comparisons between measurements and prediction of jet noise. Part 2: chocked jet noise. Sub-part 4: spectrum (2016)
  • Report PhR16-202  Comparisons between measurements and prediction of jet noise. Part 3: undefined jet noise. Sub-part 2: sound power  (2016)
  • Report PhR16-204  Comparisons between measurements and prediction of jet noise. Part 3: undefined jet noise. Sub-part 4: spectrum (2016)
  • Report PhRxx-211  Comparisons between measurements and prediction of jet noise. Part 1: spectrum of turbulence noise (20xx)
  • Report PhRxx-212  Comparisons between measurements and prediction of jet noise. Part 2: spectrum of shock noise (20xx)
  • Report PhRxx-213  Comparisons between measurements and prediction of jet noise. Part 3: power of unspecified noise (20xx)
  • Report PhR16-221  Comparisons between measurements and predictions of safety valves noise (emissions). Part 1: flow indicators (2016)
  • Report PhR16-222  Comparisons between measurements and predictions of safety valves noise (emissions). Part 2: noise level (2016)
  • Report PhR16-230  Comparisons between measurements and predictions of piping systems flow indicators (2016)
  • Report PhR17-241  Comparisons between measurements and prediction of the acoustic performance of simple expansion chamber muffers without extended tubes. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-242  Comparisons between measurements and prediction of the acoustic performance of simple expansion chamber muffers without extended tubes. Part 1: insertion loss with or without flow (2017)
  • Report PhR17-251  Comparisons between measurements and prediction of the acoustic performance of simple expansion chamber muffers with inlet extended tube. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-261  Comparisons between measurements and prediction of the acoustic performance of simple expansion chamber muffers with outlet extended tube. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-271  Comparisons between measurements and prediction of the acoustic performance of simple expansion chamber muffers with inlet & outlet extended tubes. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-281  Comparisons between measurements and prediction of the acoustic performance of double expansion chamber muffers without extended tubes. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-291  Comparisons between measurements and prediction of the acoustic performance of double expansion chamber muffers with inlet extended tube. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-301  Comparisons between measurements and prediction of the acoustic performance of double expansion chamber muffers with outlet extended tube. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-311  Comparisons between measurements and prediction of the acoustic performance of double expansion chamber muffers with inlet & outlet extended tubes. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-321  Comparisons between measurements and prediction of the acoustic radiation of a termination being open & unflanged. Part 1: end correction (2017)
  • Report PhR17-322  Comparisons between measurements and prediction of the acoustic radiation of a termination being open & unflanged. Part 2: reflection coefficient (2017)
  • Report PhR17-323  Comparisons between measurements and prediction of the acoustic radiation of a termination being open & unflanged. Part 3: radiation impedance (2017)
  • Report PhR17-331  Comparisons between measurements and prediction of the acoustic radiation of a termination being open & flanged. Part 1: end correction (2017)
  • Report PhR17-332  Comparisons between measurements and prediction of the acoustic radiation of a termination being open & flanged. Part 2: reflection coefficient (2017)
  • Report PhR17-333  Comparisons between measurements and prediction of the acoustic radiation of a termination being open & flanged. Part 3: radiation impedance (2017)
  • Report PhR17-341  Comparisons between measurements and prediction of the acoustic radiation of a termination being connected & coaxial. Part 1: end correction (2017)
  • Report PhR17-351  Comparisons between measurements and prediction of the acoustic radiation of a termination being connected & staggered. Part 1: end correction (2017)
  • Report PhR17-381  Comparisons between measurements and prediction of the acoustic performance of triple expansion chamber muffers without extended tubes. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-391  Comparisons between measurements and prediction of the acoustic performance of triple expansion chamber muffers with inlet extended tube. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-401  Comparisons between measurements and prediction of the acoustic performance of triple expansion chamber muffers with outlet extended tube. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-411  Comparisons between measurements and prediction of the acoustic performance of triple expansion chamber muffers with inlet & outlet extended tubes. Part 1: transmission loss with or without flow (2017)
  • Report PhR17-421  Comparisons between measurements and prediction of the acoustic performance of simple expansion chamber muffers with overlapping tubes. Part 1: transmission loss with or without flow (2017)

Sound enclosures for gas turbines (November 2016)

Energy production based on the use of gas turbines (in single cycle or in combined cycle), is widely used in countries without a highly developed nuclear power plant fleet.

Such power stations make possible to have large production capacities within a relatively short period of time in order to satisfy the growing needs of the populations.

In many cases, these facilities base the very existence of the electrical network of regions or countries.

In other cases, gas-fired power stations are used to manage electricity consumption peaks when other modes of production, even at full capacity, are temporarily insufficient in view of increased demand e.g. due to exceptional circumstances.

Such installations involve very powerful thermodynamic rotating machine using fossil fuels being in particular gaseous (e.g. natural gas) or liquids (e.g. fuel oil, crude oil) whose noise emissions are very high and require means of preventing nuisance for the personnel of the power plant as for its neighbors.

ITS will participate in the construction of sound enclosures for two high-power gas turbines (more than 120 MW in single cycle, more than 190 MW in combined cycle) for a power plant in the Middle East.

The overall acoustic performance of these soundproofing equipment will be due to their ability to prevent the propagation of noise - very important in terms of sound power level: typically 135 dB (A) and very broad in terms of frequency spectrum: typically 20 to 20 kHz - towards the outside of the power plant, not only through its wall and roof, but also through the components of the sophisticated ventilation systems required for proper operation.

The modalities of assembly and dismantling / reassembly of these equipments will be functionalities significantly impacting their quality and their durability, taking into account the site data (e.g. climatic conditions, seismic risks) and local building codes superimposing on international rules and standards being  otherwise all important challenges for such a project.

Improving the acoustics of a meeting room (January 2017)

A meeting room is a space for which the objective in terms of acoustics is to offer to the participants (actors or spectators of the meeting) a comfort for speech and listening during an extended period of time even though, (especially in the frequency range 500-2000 Hz), the speech intelligibility may be insufficient due to inappropriate quality of the construction (sometimes: although the premises are recent and therefore supposed to take into account the auditory well-being of the occupants as it should be self-evident nowadays). 

For a meeting room, such a symptom of a lack of acoustic comfort frequently causing recriminations can (often) be directly related to an excessive reverberation of the considered space and (thus) require remedial actions. 

Indeed, the results of the reverberation time measurements carried out in such cases often indicate that the internal acoustics of the space under consideration are perfectible, notwithstanding the absence of specific regulations applicable in this case. 

ITS will contribute to improve the acoustic comfort of a meeting room (capable of accommodating up to 120 people), near Lyon (Rhône-Alpes region, France) in relation to a situation involving existing office premises (yet new) that one might consider (at least for some of them), unsuitable for their use since they are perfectly devoid of materials capable of absorbing sounds. 

The improvement of the acoustic performance (in relation to its duration of reverberation) of what is for the time being a very reverberant ready-to-fit platform will imply the use of absorbent acoustic linings for some wall and for the roof (the considered space is located on the top floor of an office building) carefully selected for their acoustical properties. 

On the one hand, the design of the installations aiming at increasing auditory comfort, based on a distribution of the absorbent materials and on installation systems harmonized with the existing architectural choice (i.e. the enhancement of the metal elements of building structure and envelope) and on the other hand the selection of colors particularly becoming and luminous will contribute - no doubt - to obtain a meeting room keeping all promises, i.e. where it will be good to meet to inquire, to share information and even to debate in a constructive way as it should in a professional context.

Filtration systems for gas turbines (December 2016)

Gas turbines are a mode of production of electric power, privileged over others for variables reasons depending on the case, including sometimes the fact that it involves power stations of which footprint is moderate (when compared to the footprint of coal-fired plants or of nuclear power stations), which can be therefore a priori implanted almost everywhere and whose location can be notably guided by the proximity of consumers (e.g. in industrial zones when it is not in a semi-urban environment) or by the proximity of fuel deposits (e.g. gas, crude oil).

The fight against noise pollution that they may generate is not the only field of intervention of ITS.

Indeed, these plants with very variable production capacity (from a few MW for the smallest ones to several hundred MW for the largest ones) are based on the use of machine affiliated to internal combustion engine requiring combustion air and a fluid for its (complex) forced ventilation systems sufficiently clean.

In case of plants which are sometimes located in places as hostile as a desert where recurring sandstorms occur, specific devices must be envisaged in order to allow the proper functioning and durability of the various high-tech equipment involved by the various operating principles used.

ITS will participate in the construction of filtration systems for two high-power gas turbines (more than 120 MW single cycle, more than 190 MW combined cycle) for a power plant in North Africa.

The quality of the air once filtered will obviously constitute a major criterion of judgment of the quality of these systems, the modalities of their maintenance (e.g. the replacement of the consumables) also constituting an essential aspect.

As often happens for installations upgrading projects providing the implementation a posteriori of equipment not originally planned, the design of devices which are both efficient and compatible with the existing equipment e.g. sufficiently compact to enable their addition in a gas turbine environment where little space is available for them will be a major challenge.

As always in regard to gas turbines filtration, the choice of optimum filter media and their integration in a sophisticated system whose piloting requires specific instrumentation will be key factors for success.

Soundproofing works in a power plant (February 2017)

Gas-fired power plants are based on the use of combustion turbines whose noise emissions (as well as those of their ancillary equipment) are very important: they should be maintained at an acceptable level for the neighborhood as well as for the employees operating within the perimeter of the plant.

Among the most notable sources of noise, mention may be made of the turbine itself, of course, but also of the gas module, of the injection module or even of sets of duct surfaces, in particular in the upstream part of the exhaust system, where the sound emissions are not attenuated by a silencer.

In such cases, it is necessary to design and construct soundproofed buildings to limit noise diffusion, with ventilation systems being appropriate to the evacuation of the calorific energy dissipated by the various organs.

ITS will be involved in soundproofing works in a power plant whose production is based on the use of a high-power gas turbine (more than 120 MW in single cycle, over 190 MW in combined cycle) in western Africa.

The goal of the project will be to not exceed the limits for exposure to noise, namely in relation to a sound power level for the turbine of the order of 135 dB (A), which is very wide in terms of frequency spectrum (typically 20 to 20 kHz).

International rules and standards will be applied for the design and construction of the considered buildings, for which removable sub-assemblies, sometimes of large dimensions, will have to be provided for the maintenance operations of the various enclosed hardware.

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