In order to cut down excessive experiments, acoustic response of the different fan ducted discharge (equipment) was studied based on numerical method. The sound pressure level(SPL) in each component of a duct-plenum-r...In order to cut down excessive experiments, acoustic response of the different fan ducted discharge (equipment) was studied based on numerical method. The sound pressure level(SPL) in each component of a duct-plenum-reverberant room model was drawn and SPL deviation was analyzed. The trends of the curves were explained by the diffracti on and end reflection at the duct discharge. Models with different room dimensions, duct lengths, duct cross sections, duct locations and duct elbow were constructed, and their response was analyzed and compared. The results show that the SPL curves are smooth in the duct discharge cross section, but seriously fluctuant in the reverberant room; SPL in the duct discharge is only sensitive to duct dimensions, while that of the reverberant room is regularly influenced by all the dimension and arrangement factors. Small room and short duct help to increase room SPL. Elbow has an indistinct influence on all the components’ sound field. Finally, suggestion to reduce the deviation of experiment results was proposed.展开更多
The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-...The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies.展开更多
The article presents a new approach to the tasks of noise assessment and reduction in the urbanized environment endangered by road noise sources. It was proposed to include the acoustic quality model in the currently ...The article presents a new approach to the tasks of noise assessment and reduction in the urbanized environment endangered by road noise sources. It was proposed to include the acoustic quality model in the currently applied quantitative noise assessment in the management of urbanized environment. In particular, this model takes into account subjective features of sound quality, i.e.： loudness, sharpness, roughness, and fluctuation strength as well as noise mmoya^ce assessment obtained in laboratory conditions. The proposed way can be used in estimating investment costs of an acoustic barrier at the design stage展开更多
文摘In order to cut down excessive experiments, acoustic response of the different fan ducted discharge (equipment) was studied based on numerical method. The sound pressure level(SPL) in each component of a duct-plenum-reverberant room model was drawn and SPL deviation was analyzed. The trends of the curves were explained by the diffracti on and end reflection at the duct discharge. Models with different room dimensions, duct lengths, duct cross sections, duct locations and duct elbow were constructed, and their response was analyzed and compared. The results show that the SPL curves are smooth in the duct discharge cross section, but seriously fluctuant in the reverberant room; SPL in the duct discharge is only sensitive to duct dimensions, while that of the reverberant room is regularly influenced by all the dimension and arrangement factors. Small room and short duct help to increase room SPL. Elbow has an indistinct influence on all the components’ sound field. Finally, suggestion to reduce the deviation of experiment results was proposed.
基金Project(11174065)supported by the National Natural Science Foundation of China
文摘The multi-dimensional time-domain computational fluid dynamics(CFD) approach is extended to calculate the acoustic attenuation performance of water-filled piping silencers. Transmission loss predictions from the time-domain CFD approach and the frequency-domain finite element method(FEM) agree well with each other for the dual expansion chamber silencer, straight-through and cross-flow perforated tube silencers without flow. Then, the time-domain CFD approach is used to investigate the effect of flow on the acoustic attenuation characteristics of perforated tube silencers. The numerical predictions demonstrate that the mean flow increases the transmission loss, especially at higher frequencies, and shifts the transmission loss curve to lower frequencies.
文摘The article presents a new approach to the tasks of noise assessment and reduction in the urbanized environment endangered by road noise sources. It was proposed to include the acoustic quality model in the currently applied quantitative noise assessment in the management of urbanized environment. In particular, this model takes into account subjective features of sound quality, i.e.： loudness, sharpness, roughness, and fluctuation strength as well as noise mmoya^ce assessment obtained in laboratory conditions. The proposed way can be used in estimating investment costs of an acoustic barrier at the design stage
