A database of PIV measurements within a turbomachinery stage and sample comparisons with unsteady RANS

Uzol, Oğuz
Chow, Y.-C.
Katz, J.
Meneveau, C.
This paper describes an experimental database obtained using two-dimensional Particle Image Velocimetry (PIV) measurements within an axial turbomachinery stage, and presents sample unsteady Reynolds Averaged Navier - Stokes (RANS) simulations to illustrate its applicability for turbomachinery model validation. The experiments are performed in a refractive-index-matched facility that provides unobstructed view, and cover the entire second stage of a two-stage axial pump. The data were obtained at ten different rotor phases covering one rotor blade-passing period, and at mid-span. Several features of the data at selected phases have already been presented and discussed in prior publications. Here we present the complete database together with sample CFD results. Two-dimensional unsteady RANS simulations are performed using the commercial flow solver FLUENTTM, with two standard turbulence models, i.e. Renormalization Group (RNG) k-epsilon and Reynolds Stress Transport Model (RSM). The spatially non-uniform inlet velocity and turbulence boundary conditions are provided from the experimental data. Detailed side-by-side comparisons of measured and computed velocity as well as turbulence fields within the entire stage are presented using line distributions within the rotor - stator gap and the stator wake regions, as well as whole-field animations. The results show that, although there is reasonable agreement, in general, between the experimental results and the computational simulations, some critical flow features are not correctly predicted. The turbulent kinetic energy levels are generally too high in the simulations, with substantial amount of unphysical turbulence generation near the blade leading edges, especially in the case of RNG k-epsilon model. Also, wake diffusion is underestimated. The results highlight the usefulness of comparisons that cover the entire unsteady flow in a passage, as afforded by the present database and side-by-side animations.


A variational multiscale constitutive model for nanocrystalline materials
Gürses, Ercan (Elsevier BV, 2011-03-01)
This paper presents a variational multi-scale constitutive model in the finite deformation regime capable of capturing the mechanical behavior of nanocrystalline (nc) fcc metals. The nc-material is modeled as a two-phase material consisting of a grain interior phase and a grain boundary effected zone (GBAZ). A rate-independent isotropic porous plasticity model is employed to describe the GBAZ, whereas a crystal-plasticity model which accounts for the transition from partial dislocation to full dislocation m...
A modular regularized variational multiscale proper orthogonal decomposition for incompressible flows
Eroglu, Fatma G.; Kaya Merdan, Songül; Rebholz, Leo G. (Elsevier BV, 2017-10-01)
In this paper, we propose, analyze and test a post-processing implementation of a projection-based variational multiscale (VMS) method with proper orthogonal decomposition (POD) for the incompressible Navier-Stokes equations. The projection-based VMS stabilization is added as a separate post-processing step to the standard POD approximation, and since the stabilization step is completely decoupled, the method can easily be incorporated into existing codes, and stabilization parameters can be tuned independe...
An accurate nonlinear 3d Timoshenko beam element based on Hu-Washizu functional
Soydas, Ozan; Sarıtaş, Afşin (Elsevier BV, 2013-09-01)
An accurate 3d mixed beam element that is efficient especially in nonlinear analysis is presented in this paper. The mathematical theory is based on Hu-Washizu principle that uses three-fields in the variational form. The composition of the variational form ensures independent selection of displacement, stress and strain fields. Timoshenko beam theory is extended to three dimensions for deriving strains from displacement field. Numerical integration of stress strain relations along control sections is carri...
A fully implicit finite element method for bidomain models of cardiac electromechanics
Dal, Hüsnü; Göktepe, Serdar (Elsevier BV, 2013-01-01)
We propose a novel, monolithic, and unconditionally stable finite element algorithm for the bidomain-based approach to cardiac electromechanics. We introduce the transmembrane potential, the extracellular potential, and the displacement field as independent variables, and extend the common two-field bidomain formulation of electrophysiology to a three-field formulation of electromechanics. The intrinsic coupling arises from both excitation-induced contraction of cardiac cells and the deformation-induced gen...
Search for Dijet Resonances in 7 TeV pp Collisions at CMS
Khachatryan, V.; et. al. (American Physical Society (APS), 2010-11-01)
A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9 pb(-1) collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence ...
Citation Formats
O. Uzol, Y.-C. Chow, J. Katz, and C. Meneveau, “A database of PIV measurements within a turbomachinery stage and sample comparisons with unsteady RANS,” JOURNAL OF TURBULENCE, pp. 1–20, 2007, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/43266.