连续式风洞大开角扩散段流动控制数值模拟

NUMERICAL SIMULATION OF FLOW CONTROL OF WIDE-ANGLE DIFFUSER IN CLOSED-CIRCUIT CONTINUOUS TRANSONIC WIND TUNNEL

在连续式跨声速风洞中，大开角对抑制压缩机尾流扰动和提高换热器入口气流品质有重要作用，依靠设计经验和上程估算等传统风洞设计方法，无法对大开角扩散段流动控制进行有效设计。为增强大开角扩散段防分离能力，提高出口气流品质，降低损失，采用计算流体力学方法，结合适当的边界条件，对使用阻尼网进行整流的不同设计方案进行了模拟，从结果可以看到，阻尼网布置位置和开孔率对大开角段内和出151的流动状态有很大影响，第一层阻尼网应位于分离点之前，开孔率介于0．6～0．66，第二层阻尼网布置位置应靠近出口，开孔率介于0．56～0．66之间；最后对大开角段内的流动机理和压力恢复效率进行了探讨。研究结果表明：数值模拟能够得出较为合理的参数匹配，有效提高流场指标。

The wide-angle diffuser （WAD） plays a vital role to restrain compressor wake distortion and to im- prove the flow quality before the heat exchanger in a closed-circuit continuous transonic wind tunnel. There is no reasonable path to design an optimal WAD with screens based on the design method of a conventional wind tun- nel, such as the previous design experience and engineering correlations technology. The computational fluid dy- namics （CFD） with proper boundary conditions was used to compare the performance of different configurations for capacity of separation control, the improvement of the outlet flow quality and decrease of the pressure loss. The position and opening to the sectional area ratio of screens has an important effect on the flow regimes inside and outlet of WAD based on the details of numerical results. The first screen should be placed at just before the separation point, and the ratio of opening to sectional area is between 0.6 and 0.66. It is recommended that the second screen is near to the outlet of WAD using the porosity of 0.56-0.66. Flow behaviors in WAD, such as uniformity, separation and turbulence level, were significantly improved by the certain combination of the pa- rameters mentioned above. Further investigations on flow mechanism and pressure recovery efficiency were taken It is concluded that the optimal design of WAD could be obtained in terms of numerical results.