抽吸孔板的气动实验及附面层抽吸数值模拟

 为了给附面层抽吸提供可靠的抽吸边界条件 ,通过对孔板厚径比t/d =0.1～ 2.67,开孔率ε =6.3%～ 23%的多孔板进行实验 ,建立了附面层抽吸孔板小孔马赫数与孔板前后压差、孔板厚径比、孔板开孔率间的关系。发现随着孔板前后压差的加大 ,小孔马赫数增加 ,当孔板前后压差达到一定值时 ,小孔发生壅塞 ,小孔马赫数不再变化 ,孔内流动达到壅塞状态。与此同时 ,总结出了附面层抽吸孔板小孔马赫数的经验公式。为了进一步检验所得经验式的准确性 ,还用实验所得经验式作为附面层抽吸边界条件 ,对来流马赫数分别为1.98,1.58和 0.8三种情况下的附面层抽吸流场进行了数值模拟。计算结果准确反映了超声来流和亚声来流条件下的附面层抽吸的流动特征 ,抽吸流量与Willis和Syberg的实验结果吻合较好 ,表明给定的附面层抽吸边界条件是正确、可行的。

EXPERIMENTAL INVESTIGATION OF AERODYNAMIC CHARACTERISTICS OF POROUS PLATES AND NUMERICAL SIMULATION OF BOUNDARY LAYER SUCTION

An experimental investigation of aerodynamic characteristics of porous plates is performed in order to develop a reliable boundary layer condition for the numerical simulation of the flow with boundary layer suction. In the experiments, the ratio t/d of the plate thickness to the hole diameter ranges from 0.1 to 2.67 and the porosity ε of the plate from 6.3% to 23%. The experimental results show that the average Mach number in the hole relates with pressure drop over the porous plate, the ratio of the plate thickness to the hole diameter and the porosity of the plate. The Mach number in the hole will increase with the increase of pressure drop over the porous plate for a given plate. When the pressure drop reaches a certain value, the average Mach number in the hole will remain a constant value and the flow in the hole reaches the critical state. An empirical relation about the Mach number in the hole, pressure drop over the porous plate, the ratio of the plate thickness to the hole diameter and the porosity of the plate is established in this paper. In order to validate the empirical formula for boundary layer suction, numerical simulation of flow over a flat plate with boundary layer suction at free Mach number of 1.98, 1.58 and 0.8 is fulfilled by use of the empirical formula for boundary layer suction. The characteristics of flow over the porous plate are reasonably simulated and the flow rate of suction is in fairly good agreement with experimental data reported by B.P.Willis and J.Syberg. Therefore, the empirical formula described in this paper can be used in the numerical simulation of intake flow field with boundary layer suction.