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 fans, engines 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 walls in industry, metal cladding in the construction or for claustras intended for offices or canteens).

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 and updated, over time, by the human resource of ITS.

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