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Influence of pre-history and leading edge contouring on aero-performance of a 3D nozzle guide vane
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.ORCID iD: 0000-0001-5162-2289
Siemens LLC Energy Oil & Gas Design Department, Rusia.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.ORCID iD: 0000-0002-1033-9601
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
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2013 (English)In: Proceedings of the ASME Gas Turbine India Conference -2013- ; presented at ASME 2013 Gas Turbine India Conference, December 5-6, 2013, Bangalore, India, ASME Press, 2013Conference paper, Published paper (Refereed)
Abstract [en]

Experiments are conducted to investigate the effect of the pre-history in the aerodynamic performance of a threedimensional nozzle guide vane with a hub leading edge contouring. The performance is determined with two pneumatic probes (5 hole and 3 hole) concentrating mainly on the endwall. The investigated vane is a geometrically similar gas turbine vane for the first stage with a reference exit Mach number of 0.9. Results are compared for the baseline and filleted cases for a wide range of operating exit Mach numbers from 0.5 to 0.9. The presented data includes loading distributions, loss distributions, fields of exit flow angles, velocity vector and vorticity contour, as well as, mass-averaged loss coefficients. The results show an insignificant influence of the leading edge fillet on the performance of the vane. However, the pre-history (inlet condition) affects significantly in the secondary loss. Additionally, an oil visualization technique yields information about the streamlines on the solid vane surface which allows identifying the locations of secondary flow vortices, stagnation line and saddle point.

Place, publisher, year, edition, pages
ASME Press, 2013.
Keyword [en]
Aero-dynamic performance, Gas turbine vanes, Loading distribution, Loss coefficients, Loss distribution, Nozzle guide vanes, Three-dimensional nozzles, Visualization technique, Aerodynamics, Gas turbines, Mach number, Nozzles
National Category
Energy Engineering
Research subject
SRA - Energy
Identifiers
URN: urn:nbn:se:kth:diva-92190ISI: 000349928500021Scopus ID: 2-s2.0-84896678919OAI: oai:DiVA.org:kth-92190DiVA: diva2:512602
Conference
ASME 2013 Gas Turbine India Conference, GTINDIA 2013; Bangalore, Karnataka; India; 5 December 2013 through 6 December 2013
Note

QC 20140625

Available from: 2012-03-28 Created: 2012-03-28 Last updated: 2017-11-29Bibliographically approved
In thesis
1. Aerodynamic Investigations of a High Pressure Turbine Vane with Leading Edge Contouring at Endwall in a Transonic Annular Sector Cascade
Open this publication in new window or tab >>Aerodynamic Investigations of a High Pressure Turbine Vane with Leading Edge Contouring at Endwall in a Transonic Annular Sector Cascade
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Efficiency improvement is an important aspect to reduce the use of fossil-based fuel in order to achieve a sustainable future. Gas turbines are mainly fossil-fuel based turbomachines, and, therefore, efficiency improvement is still the subject of many on-going research activities in the gas turbine community. This study is incorporated into a research project that investigates design possibilities of efficiency improvement at the high pressure turbine (HPT) stage.

In the search for HPT-stage efficiency gains, leading edge (LE) contouring near the endwall is one of the methods found in the published literature that has shown a potential to increase the efficiency by decreasing the amount of secondary losses. The overall objective of the thesis is to contribute to the development of gas turbine efficiency improvements in relation to the HPT stage. Particularly, the influence of the LE fillet on losses and flow structure is investigated concentrating on the secondary flow. The core investigation is of an experimental nature. Detailed investigations of the flow field in an annular sector cascade (ASC) are presented with and without the LE fillet, using a geometric replica of a modern gas turbine nozzle guide vane (NGV) with a contoured tip endwall. Furthermore, a separate investigation is performed on a hub-cooled NGV, which focuses on endwalls, specifically the interaction between the hub film cooling and the mainstream (MS).

The experimental investigations indicate that the LE fillet has no significant effect on the flow and energy losses of the investigated NGV. The reason why the LE fillet does not affect the losses might be due to the use of a three-dimensional vane with an existing typical fillet over the full hub and tip profile. Findings also reveal that the complex secondary flow depends heavily on the incoming boundary layer. Oil flow visualisation for the baseline case displays a clear saddle point, with a separation line where the horseshoe (HS) vortex separates into the suction side (SS) and the pressure side (PS), whereas for the filleted case, the saddle point is not noticeable. The investigation of a cooled vane, using a tracer gas carbon dioxide (CO2), reveals that the upstream platform film coolant is concentrated along the SS surfaces and does not reach the PS of the hub surface, leaving it less protected from the hot gas.

Abstract [sv]

För att åstadkomma en uthållig kraftproduktion i framtiden och en minskning i användandet av fossila bränslen är effektivitetsförbättringar av central betydelse. Gasturbiner är i grund och botten fossilbaserade turbomaskiner och därför bedrivs forsknings- och utvecklingsarbete kring verkningsgradsförbättringar. Den här studien ingår i ett forskningsprojekt som undersöker designmodifieringar med målet att höja verkningsgraden för ett högtrycksturbinsteg.

Förändringar av bladets eller ledskenans framkantsgeometri nära ändväggarna har i den öppna litteraturen funnits vara en lovande metod för att minska ändväggsförlusterna. Det övergripande målet med denna studie är att bidra till utvecklingen av effektiva högtrycksturbinsteg för gasturbiner. Kärnan i undersökningen är experimentell. Särskilt påverkan från förändring av framkanten på förluster och flödesstruktur undersöks, med fokus på det sekundära flödet. Detaljerade strömningsundersökningar i ett bågformat statorgitter bestående av en geometrisk replika av en stator från en modern gasturbin presenteras, med och utan geometrisk förändring av framkanten. Vidare så genomförs en separat undersökning av en filmkyld ledskena utan framkantsförändring med fokus på interaktionen mellan filmkylningen vid inre ändväggen och huvudflödet.

De experimentella undersökningarna visar att den undersökta geometriska förändringen av framkanten inte är av signifikant betydelse för strömningsförlusterna med den studerade ledskenan. Anledningen till att designförändringen inte påverkar förlusterna kan bero på användandet av en tredimensionell ledskena med en existerande typisk kärlradie mellan ledskenan och ändväggarna. Observationerna visar också att den komplexa ändväggsströmningen är starkt beroende av det inkommande gränsskiktets egenskaper. Oljevisualisering för referensledskenan visar en tydlig stagnationspunkt på ändväggen där gränsskiktet delas upp likt en hästskoformation i virvlar på sug- respektive trycksidan av ledskenan. För den modifierade framkanten har ingen tydlig stagnationspunkt på ändväggen observerats. Spårgasundersökningar med den filmkylda ledskenan visar att filmkylningen på den inre plattformen är koncentrerad längs sugsidan och når inte trycksidan på plattformen som därmed är mindre skyddad mot den varma gasströmningen.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xx, 93 p.
Series
Trita KRV Report, ISSN 1100-7990 ; 12/02
Keyword
high pressure turbine, secondary flow, leading edge contouring, endwall, experimental investigations, losses, flow field, hub cooling flow, högtrycksturbinen sekundärströmning, framkantsmodifiering, ändvägg, experimentell undersökning, förluster, strömningsfält, filmkylning av inre platform
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-92204 (URN)978-91-7501-293-3 (ISBN)
Presentation
2012-04-13, M3, Brinellvägen 64, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20120330Available from: 2012-03-30 Created: 2012-03-28 Last updated: 2012-04-17Bibliographically approved

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