The analysis and optimization of an axial compressor

[摘要] ENGLISH ABSTRACT: Axial compressors are widely used in a variety of contexts. When compared to centrifugal compressors, axial compressors offer higher pressure ratios and efficiencies. Due to the complex relationship between blade shape and compressor performance, as well as the sensitivity of axial compressors to massflowrates, the design of an axial compressor is a challenging problem. These design difficulties can be circumvented using numerical design optimization.In this work, meta-model based design optimization (MBDO), a variant of numerical design optimization, is used to develop replacement blades for a low speed axial compressor. Two numerical models were developed: a lowfidelity, computationally inexpensive single stage model and a high fidelity, computationally expensive three stage model. For reasons of computational cost, the single stage model was used to evaluate the objective function in theoptimization process.An optimized blade design was developed, which delivered a 9:83% increase in pressure coefficient over the original design, when evaluated with the singlestage model. This increase was not sustained when evaluating the optimized design with the three stage model. After investigation, the cause was foundto be a high incidence angle near the hub and shroud, just outside the range in which incidence angle was constrained in the design problem. To compensate for this, the blade angles were manually adjusted, in order to lower theincidence angle. The adjusted blades delivered an increase of 8:54% over the original design, when evaluated with the three stage model.

[发布机构] Stellenbosch University