Vortex structures and heat transfer in a wall-bounded pin matrix: LES with a RANS wall-treatment

The present paper reports on the analysis of the motion of adhesive particles and deposit formation in a 3D linear compressor cascade in order to investigate the fouling in turbomachinery flows. The unsteady flow field is provided by a prior hybrid large-eddy simulation (LES)/Reynolds-averaged Navier-Stokes (RANS) computation. The particles are individually tracked and the deposit formation is evaluated on the basis of the well-established Thornton and Ning model. Although the study is limited to three regions of the blade, where the most relevant turbulent phenomena occurs, the prediction of fouling shows good agreement with real situations. Deposits form near the casing and the hub, in the zones where there are strong vortical structures originated by the tip leakage and hub vortices. On the blade, the deposit analysis is focused on three main regions: (a) along the stagnation region on the leading edge; (b) on the suction side, where the particles are conveyed by the hub vortex towards blade surfaces; and (c) on the pressure side, where a clean zone forms between leading edge and the blade surface, as can be seen in real compressors. [DOI: 10.1115/1.4006840

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“…Details of the model and numerical validation are presented in Ref. [15] and are not reported here for brevity.…”

Section: Flow Configuration and Dispersion/deposition Modelmentioning

confidence: 99%

“…In the last few decades, computing power has been increasing rapidly; hence, numerical models and simulations are widening the field of application, including the detailed description of the turbulence in industrial applications [12][13][14][15], the particle tracking, and deposit formation analysis (i.e., Refs. [16][17][18][19]).…”

Section: Introductionmentioning

confidence: 99%

An Integrated Particle-Tracking Impact/Adhesion Model for the Prediction of Fouling in a Subsonic Compressor

Borello

Rispoli

Venturini

2012

Journal of Engineering for Gas Turbines and Power

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“…the flow in a bundle of staggered cylinders placed between heated endwalls simulating internal cooling of turbine blades [5] and the tip leakage flow in a 3D linear compressor cascade [3]. It an ongoing project the ζ -f model is used as near wall counterpart for a seamless hybrid LES/RANS approach [3,6].…”

Section: Rans Equationsmentioning

confidence: 99%

DNS Scrutiny of the ζ-f Elliptic-Relaxation Eddy-Viscosity Model in Channel Flows with a Moving Wall

Borello

Orlandi

2011

Flow Turbulence Combust

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In this paper we present a Direct Numerical Simulations (DNS) of channel flow with stationary and moving walls. Three cases, Poiseuille-type with U W /U b = 0.75, intermediate-type with U W /U b = 1.215, and Couette-type with U W /U b = 1.5 (U W and U b are the wall and the bulk velocity), were compared with the pure Poiseuille U W /U b = 0, at a bulk Reynolds number equal to 4,800 corresponding to Re τ = 288. The DNS results were used to scrutinize the capabilities of ζ -f eddy viscosity model (based on the elliptic relaxation concept) in reproducing the nearwall turbulence in non conventional flows where the shear stress structures are strongly different with respect to the cases used for models calibration. The ζ -f model (also in its basic formulation) demonstrated to have good prospects to reproduce the main phenomenology of such class of flows due to its built-in capabilities to account separately for the different (and opposite) near wall effects on turbulence: the damping due to viscosity and pressure reflection. The results of the computations demonstrated that standard ζ -f model can reasonably reproduce the phenomenology of these flows in terms of velocity and turbulent kinetic energy profiles and budgets.

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“…To the knowledge of the authors there are no LES of heat transfer from finite-height circular cylinders. Somewhat related to the present study are LES of heat transfer for other geometrical configurations, such as in pin-fin flow ( [5] -albeit here the endwall was heated and not the cylindrical pins) and in flow around heated cubes [20,25], which also represent finite-height obstacles.…”

Section: Introductionmentioning

confidence: 99%

Forced Convection Heat Transfer from a Finite-Height Cylinder

García-Villalba

Palau-Salvador

Rodi

2014

Flow Turbulence Combust

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This paper presents a large eddy simulation of forced convection heat transfer in the flow around a surface-mounted finite-height circular cylinder. The study was carried out for a cylinder with height-to-diameter ratio of 2.5, a Reynolds number based on the cylinder diameter of 44 000 and a Prandtl number of 1. Only the surface of the cylinder is heated while the bottom wall and the inflow are kept at a lower fixed temperature. The approach flow boundary layer had a thickness of about 10% of the cylinder height. Local and averaged heat transfer coefficients are presented. The heat transfer coefficient is strongly affected by the free-end of the cylinder. As a result of the flow over the top being downwashed behind the cylinder, a vortex-shedding process does not occur in the upper part, leading to a lower value of the local heat transfer coefficient in that region. In the lower region, vortex-shedding takes place leading to higher values of the local heat transfer coefficient. The circumferentially averaged heat transfer coefficient is 20% higher near the ground than near the top of the cylinder. The spreading and dilution of the mean temperature field in the wake of the cylinder are also discussed.

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Vortex structures and heat transfer in a wall-bounded pin matrix: LES with a RANS wall-treatment

Cited by 49 publications

References 15 publications

An Integrated Particle-Tracking Impact/Adhesion Model for the Prediction of Fouling in a Subsonic Compressor

An Integrated Particle-Tracking Impact/Adhesion Model for the Prediction of Fouling in a Subsonic Compressor

DNS Scrutiny of the ζ-f Elliptic-Relaxation Eddy-Viscosity Model in Channel Flows with a Moving Wall

Forced Convection Heat Transfer from a Finite-Height Cylinder

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