ACTRAN在汽车空调领域的应用 SAIC.ppt

Aero-acoustic Predictions of Industrial Dashboard HVAC Systems Industrial Context Turbulent flow in HVAC ducts is emerging as one of the key sources of automobile cabin noise ? specifications from OEM’s to suppliers Continuous reduction of development cost and timing ? need for more numerical prediction and less prototyping and testing Test Case Presentation Objective: Predict accurately the aerodynamic noise generated by an automotive ventilation duct and register Ventilation duct 5cm 12cm CFD Computations CFD computation was performed with ANSYS Fluent The boundary layer on the register vanes was not taken into account Acoustic Model Acoustic computations were performed with ACTRAN harmonic Finite/Infinite Element solver The ACTRAN model has 3 components: Source region: Finite fluid elements Aerodynamic sources computed by ACTRAN from the CFD results are applied here Second fluid region for pure propagation: Finite fluid elements No sources are present Infinite element domain: Allows noise computation in the far field Acts as a perfect non-reflecting boundary condition This model is valid up to 3000Hz Max frequency based on chosen mesh size Analysis process and theory support higher frequency analyses with finer mesh Performance CFD and CAA computations were on a standard 64 bit Linux machine Run times met industrial requirements on typical compute resources: CFD computation: ~ 15h on 18 CPU’s CAA Computation: 5 minutes per frequency on 2 CPU’s RAM consumption = 13Gb Total computational time ~ 6h30 on 2 CPU’s up to 3000Hz Results – 1/2 Sources are more intense at low frequency The main noise sources are located in the jet at low frequencies and around the register at high frequencies Acoustic Pressure Field (dB) Aerodynamic Sources Experimental Measurements Experimental measurements were performed by VISTEON in their acoustic laboratory Numerical results show good agreement with experimental measurements A better agreement could be reached?: A lo