连续式跨声速风洞轴流压缩机气动设计与低噪声设计

连续式跨声速风洞是采用轴流压缩机驱动的、可持续运行的变密度回流式风洞。一方面，此类风洞具有运行工况范围宽的典型特征，驱动风洞主回路气流的轴流压缩机需要具备在宽工况范围稳定高效运行的能力；另一方面，良好的风洞试验段动态流场品质要求轴流压缩机进出口气流噪声不高于140 dB。宽工况范围的高效稳定运行要求和低噪声设计要求给连续式跨声速风洞轴流压缩机的研制带来挑战。针对试验段马赫数为0.2～1.6的典型连续式跨声速风洞轴流压缩机研制，重点分析了连续式跨声速风洞压缩机的载荷特性；分析了以动静叶调节有效性、设计点选取、做功系数与流量系数选择、子午流道形式选择为核心内容的压缩机气动设计基本原则及轴流压缩机低噪声设计思想；给出并分析了相应的设计结果与试验测试结果。分析表明:当轴流压缩机反动度大于0.5时，动叶调节比静叶调节更有效，反之则静叶调节更有效；对于试验段马赫数为0.2～1.6的连续式跨声速风洞轴流压缩机设计而言，压缩机设计点宜选取在马赫数为1.4附近，设计点对应的流量系数和做功系数宜分别选取在0.6和0.25左右；采用等外径子午流道的形式可有效提升压缩机气动性能；合理选择压缩机级间距因子和压缩机动、静叶片数之比可有效抑制压缩机气动噪声。

Aerodynamic and aero-acoustic design of continuous transonic wind tunnel compressor

The continuous transonic wind tunnel, which is generally a closed-circuit variable-density wind tunnel, is an excellent platform for aerodynamic mechanism research and advanced aero vehicles development. A cost-effective and stable continuous transonic wind tunnel requires its driver, usually a multistage axial-flow compressor, to have wide operating range with high adiabatic efficiency and sufficient surge margin. On the other hand, the good test section flow quality requires the outlet and inlet aero-acoustic noise of the compressor lower than 140 dB. Developing a multi-stage axial-flow compressor with high adiabatic efficiency, sufficient surge margin and low noise level working under extra-wide operating conditions faces many challenges. Thus, the effectiveness of the variable geometry method, including variable rotor blade and variable stator vanes, the choice of design point and its corresponding load coefficient and flow coefficient, and the choice of meridional type and the basic principles related to low-noise axial-flow compressor design, were analyzed for the purpose of providing some guidance for designing such a compressor. For compressors with the reaction degree higher than 0.5, the variable rotor blade is more effective. For compressors with the reaction degree lower than 0.5, the variable stator vanes method is more effective than variable rotor blade method. For wind tunnels with operating range from Ma=0.2–1.6, the design point of the compressor should be around Ma=1.4 and its corresponding loading coefficient and flow coefficient are about 0.6 and 0.25 respectively. The constant tip radius meridional type has advantages in aerodynamic performance improvement. Larger rotor-stator spacing and appropriate rotor/stator number ratio are effective in suppressing the compressor noise emission.