中文摘要：

用数值方法探讨了入口射流角度对顶部对称送风方式的方腔内流动的影响．计算的物理模型为固定宽高比为1，进风角度口分别取20°，45°，70°，90°，110°，135°及160°计算结果表明，不同的射流角度对通风方腔内流动的影响是明显的．随进风角度的变化，在不同的控制参数下，方程的解呈现多样的、不稳定的非线性特征，可归结为定常解（稳态解）、周期性振荡解、非周期性振荡解．在选定的计算参数下，当进风角度的变化范围在20°≤θ≤160°时，考虑纯强制对流，θ为135°的流场最先失稳振荡；考虑自然对流的作用，θ为70°的流场最易失稳振荡．

英文摘要：

A numerical study was made on the mixed-convection in a 2D rectangular cavity using a two dimensional unsteady laminar mathematical model for investigating the influence of the inlet flow angle and the aspect ratio. The SIMPLE（semi-implicit method for pressure-linked equations） method on a staggered grid was adopted here, and the governing differential equations were discretized by the QUICK （quadratic upwind interpolation of coveetive kinematics） scheme. Numerical calculations were carried out under the air supply mode of two symmetric top side inlets with seven values of θ （inlet flow angle, defined as the angle between the inlet flow direction and x-direction） = 20°, 45°, 70°, 90°, 110°, 135°, 160°, with the Richardson number Ri = 0,0.5 and the Reynolds number（ Re, based on the rectangular cavity width and the average velocity of jet at the inlet） given in a range of 1 000 to 3 000. The numerical results show that the symmetric steady flow at θ = 135°（proved to be the most unstable with those seven values of θ） of the given air supply mode loses its stability at Re = 1 000, Ri = 0, and the flow pattern of 70° is proved to be the most unstable in the range of 0from 20° to 90° at Re = 1 000, Ri = 0.5. Results also show that depending on the values of Re and Ri, the flow inside the cavity with different inlet angle may be： steady, periodic, quasiperiodic or turbulent, even though the boundary conditions are steady and symmetric. Further, certain features of dynamical systems like bifurcation, multiplicity, etc can also be are also seen.