Three Component LDV Velocity Measurements in a Can Type Research Combustor for CFD Validation: Part 1 — Isothermal

Abstract

A two-c•oinpolleiit fibre optic LDV system has 1,c , c•11 employed to pleasure three llleall velocity colll ,uiiellts and five Revllulcls Stress cullll>lnlcllts ill it cullfined, isotllernial strollglyy swirling flowfiel(1. The prim ry ol)jectivl• is to provide complete 1)ellclllll<u•k data for cullli,a.risons with uhlliic•rio'al frrc•tlic•tiultS based oil practical lllucl.('ls for furl)ulellt swirling flows and thereby gltitle the cic•velul,lllcllt of such 111MICls. Results of initial nlodclhng work are prescutccl and even at this early stage ill the prugrmimte, the snlleriority of the Revllulcls Stress moclellhig al,l,ruaccll is clearly illustrated tirtutgll c•ulllpiIrisolls with the results from exl>erhilellt mill it tVl,ic•rtl I,• -F itiotll•1. Measurements slit )\V the radial vebsity (01111)1 il('ilt (close to the swiller exit) to he of the sal ie magiiitucl.e its the axial and swirl collipollellts. Velocity measurements obtained close to the cu1111mstur wall slloulcl be treated with1 carttiull as these were must affected it signal lluise as it result of illterllal wall rc•.fiections. NOMENCLATURE 1 = l(u + x7 2 + c7 2 ); turbulent kinetic ellergti V =pressure 11, 2', u' = fluctuating velocity c•olllpullellts X, 1', H = axial,radial and azunutlial coordinates U2 , x7 2 , zu 2 = Reyllulcls llurlll<ll stresses TIFF, 1x77, Tfm = Revllolcls sllc',tr stresses D = combustor diallle ter = axial flux of axial miionieiitnlll Go = axial flux of angular lllomnellttilll L = characteristic length scale N = sample size R, = conll>ustor radius S = swirl llullll )er U. T'. 11 -= lily lll vc•locity collll)ollellts _ axial velocity, illnllecliately upstrealll of swirlce1 = uncertainty in velocity L y) = swirler vane angle o', (J,,, la j^• = standard lleviatioll of 11ieasitrc 1 i1.1li11. radial and swirl velocities length an(l tlierel)u% smaller c•o1111nlstors, (4) improved stal,ility, (5) uniform l,atterll factor (leading to illcreased turbine life) amid (6) imiiproved l,low-off lilllits.Detailed knowledge of confined swirling flows and flames is required for proper clesigli aiitl perftn'mntince control of turbine and ramjet combustors. The majority of the research to elate has the ('(11111111)11 goal of increasing the umiderstallcliiig of such comiiplex llowlields and illlprovillg the acc uracv of the conipu-

USAF Summer Research Program - 1995 Summer Faculty Research Program Final Reports, Volume 5A, Wright Laboratory

“…), to complete the description of the flow field. Also included in these figures, for comparative purposes, are the velocity measurements made by Ahmed et al (1992) for the isothermal swirling flow case using the same geometry, swirler, and inlet reference flow velocity as used in this reacting flow study. …”