Design of a centrifugal compressor impeller for micro gas turbine application

[摘要] ENGLISH ABSTRACT: The use of micro gas turbines (MGTs) for the propulsion of unmanned aerialvehicles (UAVs) has become an industry standard. MGTs offer betterperformance vs. weight than similar sized, internal combustion engines. The frontcomponent of an MGT serves the purpose of compressing air, which issubsequently mixed with a fuel and ignited to both power the turbine which drivesthe compressor, and to produce thrust. Centrifugal compressors are typically usedbecause of the high pressure ratios they deliver per stage. The purpose of thisproject was to design a centrifugal compressor impeller, and to devise amethodology and the tools with which to perform the aforementioned. Acompressor impeller adhering to specific performance and dimensionalrequirements was designed. The new compressor was designed using a mean-lineperformance calculation code. The use of the code was vindicated throughcomparison with the results from a benchmark study. This comparison includedmean-line, Computational Fluid Dynamic (CFD), and experimental results: thenew design mean-line results were compared to the results of CFD simulationsperformed on the same design. The new design was optimised using an ArtificialNeural Network (ANN) and Genetic Algorithm. Prior to and during optimisation,the ANN was trained using a database of sample CFD calculations. A FiniteElement Analysis (FEA) was done on the optimised impeller geometry to ensurethat failure would not occur during operation. According to CFD results, the finaldesign delivered good performance at the design speed with regards to pressureratio, efficiency, and stall margin. The mechanical stresses experienced duringoperation were also within limits. Experimental results showed good agreementwith CFD results of the optimised impeller.Keywords: micro gas turbine, centrifugal compressor, impeller, CFD,experimental, optimisation, FEA.

[发布机构] Stellenbosch University