Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Interaction of acoustic waves and micron-sized surface roughness elements in a swept-wing boundary layer
KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre.
KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre.ORCID-id: 0000-0002-5913-5431
2016 (engelsk)Rapport (Annet vitenskapelig)
Abstract [en]

E↵ect of acoustic waves on the control performance of distributed micron-sized roughness elements in a swept-wing boundary layer is investigated through direct numerical simulations. The flow configuration conforms to experiments by Kachanov et al. (2015) who observed either no significant influence of acoustic waves on the transition location or small stabilisation e↵ect. In this work, a base set up for natural transition scenario is first established by introducing unsteady background noise in the boundary layer. The natural transition is then delayed using control roughness elements. Introduction of acoustic waves to the controlled flow promotes the transition location. In all these flow cases, stationary primary crossflow vortices dominate the disturbance environment and unsteady disturbances experience an explosive growth prior to transition. The spatial distribution of the energy production associated with z-type modes shows an increase in the local transfer of energy from the modified mean flow to perturbations. Simulation of flow with control roughness elements and acoustic waves as the only source of unsteady disturbances shows no influence of acoustic wave in transition to turbulence. 

sted, utgiver, år, opplag, sider
KTH Royal Institute of Technology, 2016.
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-196875OAI: oai:DiVA.org:kth-196875DiVA, id: diva2:1049476
Merknad

QC 20161125

Tilgjengelig fra: 2016-11-24 Laget: 2016-11-24 Sist oppdatert: 2016-11-25bibliografisk kontrollert
Inngår i avhandling
1. On stability and receptivity of boundary-layer flows
Åpne denne publikasjonen i ny fane eller vindu >>On stability and receptivity of boundary-layer flows
2016 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This work is concerned with stability and receptivity analysis as well as studies on control of the laminar-turbulent transition in boundary-layer flows through direct numerical simulations. Various flow configurations are considered to address flow around straight and swept wings. The aim of this study is to contribute to a better understanding of stability characteristics and different means of transition control of such flows which are of great interest in aeronautical applications.

Acoustic receptivity of flow over a finite-thickness flat plate with elliptic leading edge is considered. The objective is to compute receptivity coefficient defined as the relative amplitude of acoustic disturbances and TS wave. The existing results in the literature for this flow case plot a scattered image and are inconclusive. We have approached this problem in both compressible and incompressible frameworks and used high-order numerical methods. Our results have shown that the generally-accepted level of acoustic receptivity coefficient for this flow case is one order of magnitude too high.

The continuous increase of computational power has enabled us to perform global stability analysis of three-dimensional boundary layers. A swept flat plate of FSC type boundary layer with surface roughness is considered. The aim is to determine the critical roughness height for which the flow becomes turbulent. Global stability characteristics of this flow have been addressed and sensitivity of such analysis to domain size and numerical parameters have been discussed.

The last flow configuration studied here is infinite swept-wing flow. Two numerical set ups are considered which conform to wind-tunnel experiments where passive control of crossflow instabilities is investigated. Robustness of distributed roughness elements in the presence of acoustic waves have been studied. Moreover, ring-type plasma actuators are employed as virtual roughness elements to delay laminar-turbulent transition.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2016. s. 49
Serie
TRITA-MEK, ISSN 0348-467X ; 2016:17
Emneord
boundary layer receptivity, acoustic receptivity, swept-wing flow, crossflow vortices, roughness element, global stability analysis, direct numerical simulation, plasma actuator
HSV kategori
Forskningsprogram
Teknisk mekanik
Identifikatorer
urn:nbn:se:kth:diva-196878 (URN)978-91-7729-184-8 (ISBN)
Disputas
2016-12-09, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:15 (engelsk)
Opponent
Veileder
Merknad

QC 20161124

Tilgjengelig fra: 2016-11-24 Laget: 2016-11-24 Sist oppdatert: 2016-11-25bibliografisk kontrollert

Open Access i DiVA

fulltext(10281 kB)91 nedlastinger
Filinformasjon
Fil FULLTEXT01.pdfFilstørrelse 10281 kBChecksum SHA-512
af3bbe545c6cfdaf2892a2f9c4a21f1088d6715f0499e8ec3b63c58bc5dc4713dc24a83d86b73c369def2652bc4ba55f5b669c58927333aa61d80ee352cda63b
Type fulltextMimetype application/pdf

Personposter BETA

Shahriari, NimaHanifi, Ardeshir

Søk i DiVA

Av forfatter/redaktør
Shahriari, NimaHanifi, Ardeshir
Av organisasjonen

Søk utenfor DiVA

GoogleGoogle Scholar
Totalt: 91 nedlastinger
Antall nedlastinger er summen av alle nedlastinger av alle fulltekster. Det kan for eksempel være tidligere versjoner som er ikke lenger tilgjengelige

urn-nbn

Altmetric

urn-nbn
Totalt: 111 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf