fluent在喷管中的应用.pdf

FLUENT 在喷管流动中的应用 喷管流场模拟的技术难点 喷管流场模拟的技术难点 复杂的几何外形（尤其需要考虑到喷管内流场时） 复杂的几何外形（尤其需要考虑到喷管内流场时） 复杂的物理现象 复杂的物理现象 气流掺混、卷吸、膨胀波系与压缩波系的相互干扰 气流掺混、卷吸、膨胀波系与压缩波系的相互干扰 飞行器的工况往往有较大的变化（亚声速、跨声速与超声速） 飞行器的工况往往有较大的变化（亚声速、跨声速与超声速） 计算量大（尤其在非定常计算时） 计算量大（尤其在非定常计算时） 要求CFD软件具有如下特点： •与CAD软件有很好的接口 •多种算法 •适应于射流场的物理模型 •高性能并行技术 CTR Transition Duct Problem Description Studied experimentally by Davis and Gessner ( 1992) Computed by Demuren(1993), Sotiropoulos and Patel (1994,1995) Low Mach-number flow, ReD = 39,000 The cross-section changes from a circle to rectangle. The salient features are the pressure-driven secondary flow and stream-wise vortices. − ∇p Vector plot on the duct wall Taken from Davis and Gessner (1992) CTR Transition Duct Mesh 64,200-cell hex mesh 195,000-cell adapted mesh CTR Transition Duct Structured Vs. Unstructured Unstructured hexahedral O-type structured mesh mesh (used in this study) (used by others*) Polar singularity Highly skewed mesh *Sotiropoulos and Patel (1994, 1995) CTR Transition Duct Boundary Conditions Inlet The BC’s for the axial velocity (U) and 6 Reynolds stresses were obtained by interpolating the experimental data. V=W=0 ε was obtained from: ∂U ′ ′ =≅ ε − P u v ∂y Exit Mass-conserving extrapolation Wall Wall functions CTR Transition Duct Results - Pressure and Skin-Friction Station 5