空气滤清器声学性能模拟.ppt

1、Study of an Air Filter,Influence of an Air Filter on the Acoustic Behavior of an Air Cleaner using Actran,Objectives,Compute the acoustic transparency (Transmission loss) of an air cleaner using Actran. Study the influence of the air filter on the transmission loss and the energy balance. The freque

2、ncy range of computations is 10Hz; 3000Hz,Air Cleaner Geometry,Air Filter,The filter is made of a rubber sealing and an undulated paper sheet To model the filter within Actran, a foam layer will be placed at the filter position. This foam is modeled using the POROUS_RIGID (Biot model) formulation av

3、ailable in Actran with the following material properties: Fluid density = 1.225 kg/m3 Porosity = 0.98 Flow resistivity = 100000 N.s/m4 Tortuosity = 1.2 Viscosity =1.821e-05 Ns/m2 A more complete POROUS_UP formulation is also available (see next slide),Volume Absorbent Material,To model foam, rock wo

4、ol, Porous elements : Biot model Material properties (frequency dependant): Foam skeleton : Young modulus, density, Fluid properties : fluid density, Foam properties : tortuosity, resistivity, porosity, Rigid porous elements : same as for POROUS materials except that skeleton is rigid,Computations,A

5、 first computation is performed without the filter = the filter is replaced by standard air Plane mode is injected at the inlet side. Non reflective boundary conditions are used at the outlet side The injected power, reflected power and transmitted power are automatically outputted by Actran Then a

6、second computation is performed with the air filter Model statitistics 11236 nodes, 48198 elements CPU time : 2 seconds per frequency on a standard Win XP PC RAM consumption : 100MB,Results Transmission Loss,TL = 10*log10(Incident_Power/Transmitted_Power),Results Power Balance,Without Filter,With Filter,Results SPL Maps,SPL dB,Inlet duct,Outlet duct,Conclusions,The use of Actran to study the acoustic effect of air filter is demonstrated Actran includes the required porous material library to correctly account for this kind of components The air filter considerably reduces the acou