Performance evaluation of a micro gas turbine centrifugal compressor diffuser
Date
2013-03
Authors
Krige, David Schabort
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
ENGLISH ABSTRACT: Micro gas turbines used in the aerospace industry require high performance with
a compact frontal area. These micro gas turbines are often considered
unattractive and at times impractical due to their poor fuel consumption and low
cycle efficiency. This led to a joint effort to investigate and analyze the
components of a particular micro gas turbine to determine potential geometry and
performance improvements. The focus of this investigation is the radial vaned
diffuser which forms part of a centrifugal compressor. The size of the diffuser is
highly constrained by the compact gas turbine diameter. The micro gas turbine
under consideration is the BMT 120 KS. The radial vaned diffuser is analyzed by
means of 1-D and 3-D (CFD) analyses using CompAero and FINETM/Turbo
respectively. The aim is to design a diffuser that maximizes the total-to-static
pressure recovery and mass flow rate through the compressor with minimal flow
losses. An experimental test facility was constructed and the numerical
computations were validated against the experimental data. Three new diffusers
were designed, each with a different vane geometry. The static-to-static pressure
ratio over the radial diffuser was improved from 1.39 to 1.44 at a rotational speed
of 120 krpm. The static pressure recovery coefficient was improved from 0.48 to
0.73 with a reduction in absolute Mach number from 0.47 to 0.22 at the radial
diffuser discharge.
AFRIKAANSE OPSOMMING: Mikro-gasturbines wat in die lugvaart industrie gebruik word, vereis ‘n hoë werkverrigting met ‘n kompakte frontale area. Hierdie gasturbines word menigmaal onaantreklik geag weens swak brandstofverbruik en n lae siklus effektiewiteit. Dit het gelei tot ‘n gesamentlike projek om elke komponent van ‘n spesifieke mikro-gasturbine te analiseer en te verbeter. Die fokus van dié ondersoek is die radiale lem diffusor wat deel vorm van ‘n sentrifugaalkompressor. Die deursnee van die diffusor word deur die kompakte gasturbine diameter beperk. Die mikro gasturbine wat ondersoek word is die BMT 120 KS. Die radiale lem diffusor word geanaliseer deur middel van 1-D en 3-D (BVD) berekeninge met behulp van CompAero en FINETM/Turbo onderskeidelik. Die doelwit is om ‘n diffusor te ontwerp met ‘n verhoogde massavloei en drukverhouding oor die kompressor. ‘n Eksperimentele toetsfasiliteit is ingerig om toetse uit te voer en word gebruik om numeriese berekeninge te bevestig. Die staties-tot-stasiese drukstyging oor die radiale diffusor is verbeter van 1.39 tot 1.44 by ‘n omwentelingspoed van 120 kopm. Die statiese drukherwinningskoeffisiënt is verbeter van 0.48 tot 0.73 met ‘n vermindering in die absolute Machgetal vanaf 0.47 tot 0.22 by die radiale diffusor uitlaat.
AFRIKAANSE OPSOMMING: Mikro-gasturbines wat in die lugvaart industrie gebruik word, vereis ‘n hoë werkverrigting met ‘n kompakte frontale area. Hierdie gasturbines word menigmaal onaantreklik geag weens swak brandstofverbruik en n lae siklus effektiewiteit. Dit het gelei tot ‘n gesamentlike projek om elke komponent van ‘n spesifieke mikro-gasturbine te analiseer en te verbeter. Die fokus van dié ondersoek is die radiale lem diffusor wat deel vorm van ‘n sentrifugaalkompressor. Die deursnee van die diffusor word deur die kompakte gasturbine diameter beperk. Die mikro gasturbine wat ondersoek word is die BMT 120 KS. Die radiale lem diffusor word geanaliseer deur middel van 1-D en 3-D (BVD) berekeninge met behulp van CompAero en FINETM/Turbo onderskeidelik. Die doelwit is om ‘n diffusor te ontwerp met ‘n verhoogde massavloei en drukverhouding oor die kompressor. ‘n Eksperimentele toetsfasiliteit is ingerig om toetse uit te voer en word gebruik om numeriese berekeninge te bevestig. Die staties-tot-stasiese drukstyging oor die radiale diffusor is verbeter van 1.39 tot 1.44 by ‘n omwentelingspoed van 120 kopm. Die statiese drukherwinningskoeffisiënt is verbeter van 0.48 tot 0.73 met ‘n vermindering in die absolute Machgetal vanaf 0.47 tot 0.22 by die radiale diffusor uitlaat.
Description
Thesis (MScEng)--Stellenbosch University, 2013.
Keywords
Micro gas, Turbine performance, Centrifugal compressor, Radial diffuser, Dissertations -- Mechanical engineering, Theses -- Mechanical engineering, Gas turbines