WAVE Acoustic_WAVE声学仿真计算
合集下载
相关主题
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
Ricardo
© Ricardo plc 2006
Key Features
Advanced 3D Modelling – To obtain high frequency resolution for acoustic analysis, a silencer must be subdivided into smaller units, and details of internal pipes, baffles and perforates added. This is done using two- or three-dimensional arrays of complex Y-Junctions to form a mesh that defines each distinct volume of the silencer. The Y-Junctions are separated by 0-length ducts, which serve as boundary elements between the Y-Junctions. Open passages are created using ducts with the same diameter as the Y-Junctions while baffle holes or perforate sections are created with smaller diameter ducts.
WAVE Advanced Training
Basic Acoustic Training
© Ricardo plc 2006
Introduction
One of WAVE’s key features is its ability to accurately predict intake and exhaust noise. By predicting gas velocities at the intake and exhaust orifices, WAVE is able to supply noise source data which can be post processed to give a predicted sound pressure level. WNOISE emulates a laboratory NVH analysis system, using standard DSP techniques to process WAVE-generated data in the same way as measured data, allowing acoustic problems to be identified. WAVE allows you to run a fully coupled simulation giving simultaneous prediction of noise and performance and can therefore demonstrate any tradeoffs. Interactions between the source and the noise are captured. This coupled with our advanced 3D pre processors and sophisticated acoustic post processor means that WAVE is unparalleled as an intake and exhaust noise analysis tool. WAVE can be used to simulate a transmission loss test bench.
© Ricardo plc 2006
Leabharlann Baidu
Ricardo
Understanding WNOISE
Before comencing the tutorial it is important to get a basic understanding of WNOISE
– A WAVE model is treated as a set of potential noise sources attached to a vehicle, which may be stationary or moving. There are two basic noise sources produced by a WAVE model: flow sources such as exhaust and intake orifices and pressure sources. – Flow sources radiate noise to the free field to be measured by all free-field microphones. Any number of flow sources may be activated from a single WAVE model and any number of free-field microphones may be used to measure the radiated noise. Free-field microphones may be stationary or moving. Sources attached to a moving vehicle and/or moving microphones will give rise to Doppler effects; suitably positioned microphones will give rise to stereo effects. Combining a moving vehicle with suitably positioned microphones can give highly realistic simulations of vehicle pass-by noise.
© Ricardo plc 2006
Ricardo
Understanding WNOISE
– Once measured, either by external (free-field) or internal (pressure sensor) microphones, all noise data can be processed and analyzed in the same way. The processing and analysis system is based on typical acoustic test and measurement systems currently available. It allows for processing of steadystate and transient WAVE data in a range of ways including frequency and order analysis; order tracking; speed-spectral mapping and frequency response analysis. Plotted data may have A/B/C acoustic weighting filters applied. Acoustic weighting filters simulate the human ear’s response to sound stimuli.
© Ricardo plc 2006
– Several years ago this would have been a very labour intensive process, with mufflers taking up to a week to create. Modification of the design would require major reworking of model which again would be very laborious.
© Ricardo plc 2006
Ricardo
WAVE modeling for Acoustics
In this tutorial we will take a pre-built model as a starting point and after modifying it slightly, perform an acoustic analysis using WNOISE and WavePost. We will then identify a possible problem area and use countermeasures to try and improve the acoustics of the intake system. Using WavePost and WNOISE we should be able to easily compare results from both models and assess the impact that the modifications have had on the engine performance and intake noise.
Ricardo
© Ricardo plc 2006
Key Features
Post processing – WNOISE is one of WAVE’s dedicated post-processors. It is comprised of noise radiation models and acoustic processing and analysis tools. It is used to simulate noise measurement experiments using a WAVE model to provide the noise sources. Transmission loss test bench – The acoustic analysis capabilities within WAVE allow for modeling of an acoustic piston (speaker producing white noise) and determination of the transmission loss between two locations. Concentric tube resonator – A preprocessing capability allows the automatic modeling of a concentric tube resonator based on user-specified geometric and operating parameters. This feature significantly reduces the time and effort required to produce a WAVE model of a silencer.
Ricardo
Key Features
As we have already seen, the pre-processors WaveBuild3D and WaveMesher have made it very straightforward to create and modify analysis quality models.
Ricardo
© Ricardo plc 2006
Understanding WNOISE
Before commencing the tutorial it is important to get a basic understanding of WNOISE (cont.)
– Pressure sources are measured by WAVE’s pressure sensors placed inside ducts or junctions in the WAVE model. Analysis of pressure sensor data is often carried out to provide validation data and as input to other analysis packages requiring processed pressure data as an input. – All microphones can have measured noise transfer functions activated. Measured noise transfer functions are normally used to replicate the acoustic characteristics of a vehicle body to allow interior noise prediction.
© Ricardo plc 2006
Key Features
Advanced 3D Modelling – To obtain high frequency resolution for acoustic analysis, a silencer must be subdivided into smaller units, and details of internal pipes, baffles and perforates added. This is done using two- or three-dimensional arrays of complex Y-Junctions to form a mesh that defines each distinct volume of the silencer. The Y-Junctions are separated by 0-length ducts, which serve as boundary elements between the Y-Junctions. Open passages are created using ducts with the same diameter as the Y-Junctions while baffle holes or perforate sections are created with smaller diameter ducts.
WAVE Advanced Training
Basic Acoustic Training
© Ricardo plc 2006
Introduction
One of WAVE’s key features is its ability to accurately predict intake and exhaust noise. By predicting gas velocities at the intake and exhaust orifices, WAVE is able to supply noise source data which can be post processed to give a predicted sound pressure level. WNOISE emulates a laboratory NVH analysis system, using standard DSP techniques to process WAVE-generated data in the same way as measured data, allowing acoustic problems to be identified. WAVE allows you to run a fully coupled simulation giving simultaneous prediction of noise and performance and can therefore demonstrate any tradeoffs. Interactions between the source and the noise are captured. This coupled with our advanced 3D pre processors and sophisticated acoustic post processor means that WAVE is unparalleled as an intake and exhaust noise analysis tool. WAVE can be used to simulate a transmission loss test bench.
© Ricardo plc 2006
Leabharlann Baidu
Ricardo
Understanding WNOISE
Before comencing the tutorial it is important to get a basic understanding of WNOISE
– A WAVE model is treated as a set of potential noise sources attached to a vehicle, which may be stationary or moving. There are two basic noise sources produced by a WAVE model: flow sources such as exhaust and intake orifices and pressure sources. – Flow sources radiate noise to the free field to be measured by all free-field microphones. Any number of flow sources may be activated from a single WAVE model and any number of free-field microphones may be used to measure the radiated noise. Free-field microphones may be stationary or moving. Sources attached to a moving vehicle and/or moving microphones will give rise to Doppler effects; suitably positioned microphones will give rise to stereo effects. Combining a moving vehicle with suitably positioned microphones can give highly realistic simulations of vehicle pass-by noise.
© Ricardo plc 2006
Ricardo
Understanding WNOISE
– Once measured, either by external (free-field) or internal (pressure sensor) microphones, all noise data can be processed and analyzed in the same way. The processing and analysis system is based on typical acoustic test and measurement systems currently available. It allows for processing of steadystate and transient WAVE data in a range of ways including frequency and order analysis; order tracking; speed-spectral mapping and frequency response analysis. Plotted data may have A/B/C acoustic weighting filters applied. Acoustic weighting filters simulate the human ear’s response to sound stimuli.
© Ricardo plc 2006
– Several years ago this would have been a very labour intensive process, with mufflers taking up to a week to create. Modification of the design would require major reworking of model which again would be very laborious.
© Ricardo plc 2006
Ricardo
WAVE modeling for Acoustics
In this tutorial we will take a pre-built model as a starting point and after modifying it slightly, perform an acoustic analysis using WNOISE and WavePost. We will then identify a possible problem area and use countermeasures to try and improve the acoustics of the intake system. Using WavePost and WNOISE we should be able to easily compare results from both models and assess the impact that the modifications have had on the engine performance and intake noise.
Ricardo
© Ricardo plc 2006
Key Features
Post processing – WNOISE is one of WAVE’s dedicated post-processors. It is comprised of noise radiation models and acoustic processing and analysis tools. It is used to simulate noise measurement experiments using a WAVE model to provide the noise sources. Transmission loss test bench – The acoustic analysis capabilities within WAVE allow for modeling of an acoustic piston (speaker producing white noise) and determination of the transmission loss between two locations. Concentric tube resonator – A preprocessing capability allows the automatic modeling of a concentric tube resonator based on user-specified geometric and operating parameters. This feature significantly reduces the time and effort required to produce a WAVE model of a silencer.
Ricardo
Key Features
As we have already seen, the pre-processors WaveBuild3D and WaveMesher have made it very straightforward to create and modify analysis quality models.
Ricardo
© Ricardo plc 2006
Understanding WNOISE
Before commencing the tutorial it is important to get a basic understanding of WNOISE (cont.)
– Pressure sources are measured by WAVE’s pressure sensors placed inside ducts or junctions in the WAVE model. Analysis of pressure sensor data is often carried out to provide validation data and as input to other analysis packages requiring processed pressure data as an input. – All microphones can have measured noise transfer functions activated. Measured noise transfer functions are normally used to replicate the acoustic characteristics of a vehicle body to allow interior noise prediction.