Performance evaluation of a micro gas turbine centrifugal compressor diffuser

[摘要] ENGLISH ABSTRACT: Micro gas turbines used in the aerospace industry require high performance witha compact frontal area. These micro gas turbines are often consideredunattractive and at times impractical due to their poor fuel consumption and lowcycle efficiency. This led to a joint effort to investigate and analyze thecomponents of a particular micro gas turbine to determine potential geometry andperformance improvements. The focus of this investigation is the radial vaneddiffuser which forms part of a centrifugal compressor. The size of the diffuser ishighly constrained by the compact gas turbine diameter. The micro gas turbineunder consideration is the BMT 120 KS. The radial vaned diffuser is analyzed bymeans of 1-D and 3-D (CFD) analyses using CompAero and FINETM/Turborespectively. The aim is to design a diffuser that maximizes the total-to-staticpressure recovery and mass flow rate through the compressor with minimal flowlosses. An experimental test facility was constructed and the numericalcomputations were validated against the experimental data. Three new diffuserswere designed, each with a different vane geometry. The static-to-static pressureratio over the radial diffuser was improved from 1.39 to 1.44 at a rotational speedof 120 krpm. The static pressure recovery coefficient was improved from 0.48 to0.73 with a reduction in absolute Mach number from 0.47 to 0.22 at the radialdiffuser discharge.

[发布机构] Stellenbosch University