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Enabling high-fidelity measurements of turbulent boundary layer flow over wing sections in the MTL wind tunnel.
KTH, School of Engineering Sciences (SCI), Mechanics.
2019 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

A reinforced fiber-glass model of a NACA 4412 wing profile is designed and set-up in the Minimum Turbulence Level (MTL) wind tunnel facility at KTH. The model has 65 pressure taps orifices, and the set-up includes two mounting panels designed to allow for particle image velocimetry (PIV) and hot wire anemometry (HWA) measurements of the boundary layer (to be performed in a future campaign). In a first experimental campaign pressure scans are conducted at three angles of attack of interest (5,10 and 12 degrees), and at four different Reynolds numbers based on chord length and inflow velocity (200,000, 400,000, 1,000,000, and 1,640,000). The preliminary results show good agreement with DNS and LES data, however, the effective angle of attack of the wing is affected by the interference of the test section. In order to obtain proper flow conditions for future campaigns inside the test section, wall inserts are designed using 2D k-omega SST simulations. The side-walls are streamlined and the final geometry is corrected to account for the boundary-layer growth over them. The inserts are shown to avoid early separation near the trailing edge at higher angles of attack (10 and 12 degrees), but the 2D simulations fail to capture the aforementioned angle-of-attack issue affecting the pressure distributions. Future extensions of the present insert design should include both 3D simulations of the test-section and a robust optimization procedure to prescribe the resulting pressure distribution.

Abstract [sv]

En NACA 4412 vingprofilsmodel av förstärkt glasfiber utformas och installeras enligt Minimum Turbulence Level (MTL) i vindtunnelanläggningen på KTH. Modellen har 65 tryckluftsöppningar, och uppsättningen innehåller två monteringspaneler som är utformade för att möjliggöra mätningar av particle image velocimetry (PIV) and hot wire anemometry (HWA) hos gränsskiktet (som ska utföras i en framtida kampanj). I en första experimentell kampanj utförs tryckskanningar vid tre anfallsvinklar av intresse (5, 10, och 12 grader) samt vid fyra olika Reynolds-nummer (200 000, 400 000, 1 000 000 och 1 640 000). De preliminära resultaten visar god överensstämmelse med DNS- och LES-data, men den effektiva anfallsvinkeln på vingen påverkas av störningar från testsektionen. För att tillhandahålla korrekta flödesförhållanden för framtida kampanjer i testdelen är vägginsatser konstruerade med 2D k-omega SST-simuleringar. Sidoväggarna är strömlinjeformade och den slutliga geometrin korrigeras för att ta hänsyn till gränsiktets tillväxt. Insatserna undviker den tidig separation som sker nära bakkanten vid högre anfallsvinklar (10 och 12 grader), men 2D-simuleringarna misslyckades med att fånga det ovan nämnda anfallsvinkelproblemet som påverkar tryckfördelningarna.

Place, publisher, year, edition, pages
2019. , p. 85
Series
TRITA-SCI-GRU ; 2019:398
Keywords [en]
Fluid mechanics, aerodynamics, turbulence, RANS, wind-tunnel experiments, insert design
Keywords [sv]
Strömningsmekanik, aerodynamik, turbulens, RANS, vindtunnel experiment, inlaga designen
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-264842OAI: oai:DiVA.org:kth-264842DiVA, id: diva2:1375078
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Available from: 2019-12-04 Created: 2019-12-04 Last updated: 2019-12-04Bibliographically approved

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