弯扭管道对离心压气机失速先兆特性影响机理研究

The stall inception behaviors determined the stable operating range of compressor, which is always the hot topic in the compressor research field. Due to the limitations of space and installation, the inlet of centrifugal compressor in turbocharging system usually need to install the bent-torsional pipe, which induces the inlet distortion and thus influence the compressor performance and stability. Currently, the mechanism of inlet bent-torsional pipe influence on the stall inception behaviors of a centrifugal compressor has not been studied yet. Therefore, in the present project, for the inlet conditions of the bent and bent-torsional inlet pipes with different installation angle, the centrifugal compressor with volute has been studied. The compressor performance experiment, casing wall static pressure steady measurement and high-response unsteady pressure measurement have been conducted. And based on the unsteady simulation for the stall process, the bent-torsional pipe influence on the stall typical behaviors, such as inception position, stall region size and stall evolution process, has been studied. Then the roles of static pressure circumferential distortion and swirl distortion in the stall inception influence has been determined. The interaction effect between the inlet bent-torsional pipe and outlet volute also has been summarized. Finally, the key flow patterns for the stall inception formation structure have been revealed. The results and conclusions of the project can improve the design of inlet pipes and centrifugal compressors in turbocharging system, propose the asymmetric flow control method to widen the compressor operating range and acquire a deeper understanding for the compressor stall mechanism.

失速先兆特性决定了压气机的稳定工作范围，一直是压气机研究领域的热点。由于受到空间大小和结构布置的限制，增压系统中离心压气机进口通常安装弯扭形式的进气管道，会造成压气机进口流场畸变，影响压气机性能和稳定性。目前对弯扭管道影响压气机失速先兆特性的内在机理尚未开展充分研究，为此，本项目针对带有蜗壳的离心压气机，在具有不同安装角度的弯曲/弯扭管道的进口条件下，进行压气机性能实验、轮缘壁面静压测量和高频瞬态静压测量，并结合失速过程的非定常数值模拟，研究弯扭管道对压气失速先兆发生位置、尺度大小、发展过程等特征的影响规律；明确静压周向畸变和旋涡畸变在对失速先兆影响中的主导性问题；揭示进口弯扭管道与出口蜗壳影响间的相互作用机制；发现制约失速先兆结构的关键流动形态。研究结果将为复杂增压系统中弯扭管道及压气机的精细化设计，采用非对称流动控制措施改善压气机稳定性，完善压气机失速先兆机理等打下基础。

明确离心压气机中失速先兆的发生发展机理能够进一步提升压气机性能和稳定性，也是揭示弯扭管道进口对压气机失速特性影响机制的前提。因此本项目针对离心压气机开展了高频瞬态压力测量实验、轮缘壁面静压分布测量实验及非定常数值模拟，形成了对离心压气机失速特性及弯扭管道影响的深入认识。取得的主要成果如下：（1）基于瞬态压力测量实验，开展了采用静压波形不规则度与偏度的旋转不稳定性识别方法研究、基于自相关系数的失速预警方法研究及不同转速下离心压气机失速特性存在的差异性研究。从时域和频域角度获得了全转速下离心压气机的完整失稳路径，明确了旋转不稳定性与失速之间的差异及相互联系。（2）针对离心压气机失稳信号存在宽频分布等特点，而传统的时域频域方法在分析非线性失稳信号方面存在不足，开展了基于变分模态分解的非线性失稳信号辨识与重构方法，获得了对离心压气机失稳信号更精确的识别和更全面的分析。（3）开展了弯扭管道进口离心压气机失速先兆特性实验与数值研究，获得了在进口弯扭管道和出口蜗壳耦合作用下，离心压气机在全工况范围内周向静压分布图谱，总结出了进/出口畸变相互作用强度随压气机流量的变化规律。研究了离心压气机前缘涡结构的时空演化规律，数值模拟结果与瞬态压力测量结果相一致，进一步验证并深入揭示了离心压气机失速机理。项目完成了预定研究目标，在国内外重要学术期刊发表SCI论文6篇，包括热机气动领域权威期刊ASME Journal of Turbomachinery、Chinese Journal of Aeronautics和Energy等。