BLAST WAVE VISUALIZATION AND DENSITY MEASUREMENT AROUND CYLINDERS IN CROSS FLOW: EXPERIMENTAL AND NUMERICAL STUDY

The present work focusses on the numerical study of Vortex-Induced Vibrations (VIV) of an elastically mounted cylinder in a cross flow at moderate Reynolds numbers. Low mass-damping experimental studies show that the dynamic behavior of the cylinder exhibits a three-branch response model, depending on the range of the reduced velocity. However, few numerical simulations deal with accurate computations of the VIV amplitudes at the lock-in upper branch of the bifurcation diagram. In this work, the dynamic response of the cylinder is investigated by means of three-dimensional Large Eddy Simulation (LES). An Arbitrary Lagrangian Eulerian framework is employed to account for fluid solid interface boundary motion and grid deformation. Numerous numerical simulations are performed at a Reynolds number of 3900 for both no damping and low-mass damping ratio and various reduced velocities. A detailed physical analysis is conducted to show how the present methodology is able to capture the different VIV responses.

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Experimental and Numerical Study on the Effects of the Relative Position of Film Hole and Orientation Ribs on the Film Cooling With Ribbed Cross-Flow Coolant Channel

Volume 7B: Heat Transfer ◽

10.1115/gt2020-14389 ◽

2020 ◽

Author(s):

Bingran Li ◽

Cunliang Liu ◽

Lin Ye ◽

Huiren Zhu ◽

Fan Zhang

Keyword(s):

Heat Transfer ◽

Relative Position ◽

Film Cooling ◽

Numerical Study ◽

Cross Flow ◽

Internal Cooling ◽

Transfer Coefficients ◽

Cooling Performance ◽

Heat Transfer Coefficients ◽

Numerical Studies

Abstract To investigate the application of ribbed cross-flow coolant channels with film hole effusion and the effects of the internal cooling configuration on film cooling, experimental and numerical studies are conducted on the effect of the relative position of the film holes and different orientation ribs on the film cooling performance. Three cases of the relative position of the film holes and different orientation ribs (post-rib, centered, and pre-rib) in two ribbed cross-flow channels (135° and 45° orientation ribs) are investigated. The film cooling performances are measured under three blowing ratios by the transient liquid crystal measurement technique. A RANS simulation with the realizable k-ε turbulence model and enhanced wall treatment is performed. The results show that the cooling effectiveness and the downstream heat transfer coefficient for the 135° rib are basically the same in the three position cases, and the differences between the local effectiveness average values for the three are no more than 0.04. The differences between the heat transfer coefficients are no more than 0.1. The “pre-rib” and “centered” cases are studied for the 45° rib, and the position of the structures has little effect on the film cooling performance. In the different position cases, the outlet velocity distribution of the film holes, the jet pattern and the discharge coefficient are consistent with the variation in the cross flow. The related research previously published by the authors showed that the inclination of the ribs with respect to the holes affects the film cooling performance. This study reveals that the relative positions of the ribs and holes have little effect on the film cooling performance. This paper expands and improves the study of the effect of the internal cooling configuration on film cooling and makes a significant contribution to the design and industrial application of the internal cooling channel of a turbine blade.

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Quantitative Density Measurement of the Interaction Field of Side Jet and Cross Flow by Colored-Grid Background Oriented Schlieren (CGBOS) Technique

29th International Symposium on Shock Waves 1 ◽

10.1007/978-3-319-16835-7_78 ◽

2015 ◽

pp. 495-500

Author(s):

M. Ota ◽

T. Inage ◽

Y. Kikuma ◽

H. Kawakami ◽

Y. Miwa ◽

...

Keyword(s):

Density Measurement ◽

Cross Flow ◽

Interaction Field ◽

Background Oriented Schlieren

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Large Eddy Simulation of Cross Flow in Pipe Junction

Volume 2: CFD and FSI ◽

10.1115/omae2018-77751 ◽

2018 ◽

Author(s):

Jiajun Chen ◽

Yue Sun ◽

Hang Zhang ◽

Dakui Feng ◽

Zhiguo Zhang

Keyword(s):

Large Eddy Simulation ◽

Stokes Equations ◽

Numerical Study ◽

Three Dimensional ◽

Cross Flow ◽

Exciting Force ◽

Navier Stokes ◽

Pipe Network ◽

Eddy Simulation ◽

Large Eddy

Mixing in pipe junctions can play an important role in exciting force and distribution of flow in pipe network. This paper investigated the cross pipe junction and proposed an improved plan, Y-shaped pipe junction. The numerical study of a three-dimensional pipe junction was performed for calculation and improved understanding of flow feature in pipe. The filtered Navier–Stokes equations were used to perform the large-eddy simulation of the unsteady incompressible flow in pipe. From the analysis of these results, it clearly appears that the vortex strength and velocity non-uniformity of centerline, can be reduced by Y-shaped junction. The Y-shaped junction not only has better flow characteristic, but also reduces head loss and exciting force. The results of the three-dimensional improvement analysis of junction can be used in the design of pipe network for industry.

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Computational Fluid Dynamics Evaluation of Heat Transfer Correlations for Sodium Flows in a Heat Exchanger

Journal of Heat Transfer ◽

10.1115/1.4000707 ◽

2010 ◽

Vol 132 (5) ◽

Cited By ~ 3

Author(s):

Seok-Ki Choi ◽

Seong-O Kim ◽

Hoon-Ki Choi

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Turbulence Model ◽

Numerical Solutions ◽

Numerical Study ◽

Cross Flow ◽

Turbulence Models ◽

Parallel Flow ◽

Sst Model ◽

Heat Transfer Correlations

A numerical study for the evaluation of heat transfer correlations for sodium flows in a heat exchanger of a fast breeder nuclear reactor is performed. Three different types of flows such as parallel flow, cross flow, and two inclined flows are considered. Calculations are performed for these three typical flows in a heat exchanger changing turbulence models. The tested turbulence models are the shear stress transport (SST) model and the SSG-Reynolds stress turbulence model by Speziale, Sarkar, and Gaski (1991, “Modelling the Pressure-Strain Correlation of Turbulence: An Invariant Dynamical System Approach,” J. Fluid Mech., 227, pp. 245–272). The computational model for parallel flow is a flow past tubes inside a circular cylinder and those for the cross flow and inclined flows are flows past the perpendicular and inclined tube banks enclosed by a rectangular duct. The computational results show that the SST model produces the most reliable results that can distinguish the best heat transfer correlation from other correlations for the three different flows. It was also shown that the SSG-RSTM high-Reynolds number turbulence model does not deal with the low-Prandtl number effect properly when the Peclet number is small. According to the present calculations for a parallel flow, all the old correlations do not match with the present numerical solutions and a new correlation is proposed. The correlations by Dwyer (1966, “Recent Developments in Liquid-Metal Heat Transfer,” At. Energy Rev., 4, pp. 3–92) for a cross flow and its modified correlation that takes into account of flow inclination for inclined flows work best and are accurate enough to be used for the design of the heat exchanger.

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