Investigation of unsteady wake-separated boundary layer interaction using particle-image-velocimetry

2007-05-17
Uzol, Oğuz
Cranstone, Alex
Hodson, Howard
The current paper presents an experimental investigation of the interaction between unsteady wakes and the separated boundary layer on the suction side of an ultra-high-lift low-pressure turbine airfoil. Two-dimensional Particle Image Velocimetry (PIV) measurements of the unsteady boundary layer over the T106C LP turbine profile were performed in a low speed linear cascade facility, at selected phases of passing wakes. The wakes are created by moving cylindrical bars across the inlet of the test section. Various phenomena were investigated such as separation and transition characteristics, vortex structures within the unsteady boundary layer, their interaction and effects on the transition process, the corresponding vortex shedding mechanisms and the unsteady behaviour of the separation bubble due to the wake- boundary layer interaction. The current measurements suggest that rollup vortices are generated as the wake approaches the separated shear layer on the suction surface before the wake centerline starts impinging on the blade. At this instant, the bubble is sufficiently high for the free shear layer to roll up into a vortex and the incoming wake is highly distorted (strained) due to the velocity field within the blade passage, and the turbulence distribution within the wake is not symmetrical. Vortices within the boundary layer, identified using the swirl strength distributions calculated from the eigenvalues of the velocity gradient tensor, seem to be coalescing and forming bigger scale structures, which in turn break up into smaller but higher swirl strength eddies. In between the passing wakes, the separation bubble grows in both in height and length, trying to return to its steady state shape.
52nd ASME Turbo Expo 2007

Suggestions

Measurement of jet multiplicity distributions in t(t)over-bar production in pp collisions at root s=7TeV
Chatrchyan, S.; et. al. (Springer Science and Business Media LLC, 2014-08-01)
The normalised differential top quark-antiquark production cross section is measured as a function of the jet multiplicity in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC with the CMS detector. The measurement is performed in both the dilepton and lepton+jets decay channels using data corresponding to an integrated luminosity of 5.0 fb(-1). Using a procedure to associate jets to decay products of the top quarks, the differential cross section of the t (t) over bar production is de...
Development of an automatic design and analysis tool for axial compressors
Kündeş, Necmettin Anıl; Aksel, Mehmet Haluk; Baran, Özgür Uğraş; Department of Mechanical Engineering (2017)
In this thesis, an automatic design and analysis tool is developed for the design of an axial flow compressor and to check the required design conditions of the designed compressor by using three dimensional CFD analyses automatically. The developed tool mainly consists of six parts which are mean line design, calculations based on radial equilibrium theory, parametrization, generation of three dimensional blade geometry, mesh generation and solver. A new design study for an axial flow compressor begins wit...
Study of high-p(T) charged particle suppression in PbPb compared to pp collisions at root s(NN)=2.76 TeV
Chatrchyan, S.; et. al. (Springer Science and Business Media LLC, 2012-03-01)
The transverse momentum spectra of charged particles have been measured in pp and PbPb collisions at root s(NN) = 2.76 TeV by the CMS experiment at the LHC. In the transverse momentum range p(T) = 5-10 GeV/c, the charged particle yield in the most central PbPb collisions is suppressed by up to a factor of 7 compared to the pp yield scaled by the number of incoherent nucleon-nucleon collisions. At higher p(T), this suppression is significantly reduced, approaching roughly a factor of 2 for particles with p(T...
Investigation of the effect of structural damping on wind turbine wind-induced fatigue loads
Kocan, Cagri; Özgen, Gökhan Osman (2022-09-01)
This paper presents a quantitative investigation of the effect of structural damping ratios of the tower and blade vibration modes of wind turbines on wind-induced fatigue loads at critical blade and tower sections. Fatigue loads are used as a relative measure of fatigue life in wind turbine design applications. By increasing the structural damping ratio of each one of the critical structural modes which highly contribute to the overall vibration response, short-term and lifetime fatigue loads at critical t...
Measurement of the elliptic anisotropy of charged particles produced in PbPb collisions at root s(NN)=2.76 TeV
Chatrchyan, S.; et. al. (2013-01-01)
The anisotropy of the azimuthal distributions of charged particles produced in root s(NN) = 2.76 TeV PbPb collisions is studied with the CMS experiment at the LHC. The elliptic anisotropy parameter, upsilon(2), defined as the second coefficient in a Fourier expansion of the particle invariant yields, is extracted using the event-plane method, two- and four-particle cumulants, and Lee-Yang zeros. The anisotropy is presented as a function of transverse momentum (p(T)), pseudorapidity (eta) over a broad kinema...
Citation Formats
O. Uzol, A. Cranstone, and H. Hodson, “Investigation of unsteady wake-separated boundary layer interaction using particle-image-velocimetry,” presented at the 52nd ASME Turbo Expo 2007, Montreal, CANADA, 2007, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/40190.