基于ANSYS CFX 的噪音分析.ppt

1/25/05 ANSYS, Inc. Propietary OVERVIEW OF NOISE CAPABILITIES IN ANSYS CFX Thabet Belamri ANSYS Canada Ltd October 2006 Outline Noise modeling background Lighthill acoustic analogy Ffowcs Williams and Hawkings model Lowson Model ANSYS CFX noise capabilities Advance turbulence modelling Near field applications: automotive, turbomachinery Far field applications: turbomachinery Noise source strength calculation Conclusions Noise modeling background Noise modeling background Noise modeling background Noise modeling background Noise modeling background Noise Modeling Background Noise Modeling Background Noise Modeling Background Noise Modeling Background ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities DNS Length scale variation ? 103 Unrealistic calculation times LES Wall bounded flows ? grid requirements Boundary conditions: Inlet, walls, ... URANS Damping of small structures Single-mode behaviour ANSYS CFX Noise Capabilities Detached Eddy Simulation (DES) URANS LES Turbulence length scale vs. grid width Scale-Adaptive Simulation (SAS) Model-inherent transition URANS mode ? LES mode Less grid sensitive ANSYS CFX Noise Capabilities New k-?t model ? Rotta ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities Mesh: Box around the Plate Cylinder Height of domain: 10 diameters (D=0.2m) wall-normal distance around 1-3 *10 -4 m obstacle edges resolution: step sizes around 0.02*D (height) -0.03*D (circumf.) ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities L ? W ? D = 5 ? 1 ? 1 Depth = 0.1 m ANSYS CFX Noise Capabilities Transient pressure measured @ 10 floor locations (K20-K29) Power Spectrum Density (PSD) obtained from: Data Simulations Rossiter modes ANSYS CFX Noise Capabilities ANSYS CFX Noise Capabilities ANSYS CFX Noise Capab