【作者】 王云飞；

【导师】 陈浮；

【作者基本信息】 哈尔滨工业大学 ， 动力机械及工程， 2012， 硕士

【摘要】 近年来，微型涡轮发动机得到了航空航天、能源动力等有关领域的高度重视。高转速离心压气机作为微型涡轮发动机的核心部件之一，其性能状况至关重要。压气机在高空低雷诺数条件下工作时，由于气体的密度和温度较低，粘性力作用加强，会使得流道内的流动情况迅速恶化，从而影响其性能。因此，有必要研究雷诺数对流道内流场结构的影响，为设计不同雷诺数下高性能的离心压气机提供理论基础。本文针对某型离心压气机，利用CFX软件进行数值模拟。首先假定流动为全湍流，对单流道内部流动情况计算，得出不同雷诺数时离心压气机的工作特性线；其次，考虑蜗壳的影响对全通道流动进行计算，将得到的总性能参数与单流道计算结果相比较，并对压气机工作于近喘点、最高效率点和近堵塞点时的流动特性做了深入研究和分析；最后，考虑附面层内流动形式存在由层流向湍流的转捩情况，引入转捩模型对单流道流动状况进行计算和分析，并与全湍流模型的单流道计算结果进行了对比。研究结果表明，随着雷诺数的下降，离心压气机的效率明显降低。其工作高度为20km时的最高效率与地面状态相比，单流道全湍流模型计算时下降了约9%；全通道全湍流模型计算结果降低了10%；引入转捩模型后，单流道效率下降了8%左右。低雷诺数下，二次流损失、叶型损失等都会明显增加，气流的分离位置提前，分离区扩大，高熵增区增加，流道内还存在气流的再附、转捩以及逆转捩等复杂现象，近喘振点和近堵塞点工况处的流动情况更加恶劣，稳定工作范围显著减小，变工况性能受到影响。全通道计算时，由于蜗壳损失的影响，压气机稳定工作范围比单通道计算结果小，且工作于不同高度下最高效率值比单通道低6%左右。引入转捩模型后得到的结果为雷诺数越低，压气机效率下降越快，而且下降是非线性的。更多还原

【Abstract】 Micro turbine engine has attracted more and more attentions in the field ofaerospace and energy power in recent years. The performance condition of thecentrifugal compressor with high rotation speed, which is one of the cores of microturbine engine, plays a significant role. When the compressor is working at the lowReynolds number condition with high altitude, due to the low air density andtemperature, the viscous force enhances. So the flow situation in the passage is rapidlyworse and the performance decreases. Therefore, it is necessary to study the structure offlow field at different Reynolds numbers. It can provide a theoretical basis for thedesign of high-performance centrifugal compressor at different Reynolds numbers.A centrifugal compressor was investigated in this paper. Numerical simulationusing the CFX software was proceeded. Firstly, the flow situation of single passage wascalculated. Then characteristic lines in the conditions of different Reynolds numberswere obtained. Secondly, the result of calculation of whole passages was compared withthat of single passage. Detailed analysis of result with whole passages at differentcharacteristic points was performed. Finally, the flow situation of single passage withtransition model was calculated and analyzed.The results show that, with the drop of Reynolds number, the efficiency of thecentrifugal compressor decrease markedly. When the operating height is20kilometers,the efficiency of the compressor declines about9percent in the single passagecalculation,10percent in the whole passages calculation and8percent in the calculationof single passage with transition model respectively. The secondary flow loss andprofile loss increased significantly at low Reynolds number. The position of flowseparation moved ahead. There were reattachment, transition and inverse transition inthe flow passage. The flow situation was more severe near the working condition ofstall and choke. Owing to the effect of the volute, compared with the result ofcompressor in single passage, the stable operation range of compressor in wholepassages obviously reduces and the peak efficiency descends approximately6percent.The fall of efficiency of compressor in single passage with transition model is nonlinear.更多还原