Heat transfer and hydraulic resistance of supercritical-pressure coolants. Part II: Experimental data on hydraulic resistance and averaged turbulent flow structure of supercritical pressure fluids during heating in round tubes under normal and deteriorated heat transfer conditions

2013 ◽  
Vol 58 (1-2) ◽  
pp. 152-167 ◽  
Author(s):  
V.A. Kurganov ◽  
Yu.A. Zeigarnik ◽  
I.V. Maslakova
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbulent Flow ◽  
Hydraulic Resistance ◽  
Flow Structure ◽  
Supercritical Pressure ◽  
Turbulent Flow Structure

Heat Transfer and Hydraulic Resistance in Turbulent Flow in Vertical Round Tubes At Supercritical Pressures. Part 1. Results From Numerical Simulations Using Algebraic Turbulent Viscosity Models

2020 ◽  
Author(s):  
Georgii Glebovich Yankov ◽  
Vladimir Kurganov ◽  
Yury Zeigarnik ◽  
Irina Maslakova
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbulent Flow ◽  
Hydraulic Resistance ◽  
Turbulent Viscosity ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Heating And Cooling ◽  
Prediction Techniques ◽  
Vertical Tubes

Abstract The review of numerical studies on supercritical pressure (SCP) coolants heat transfer and hydraulic resistance in turbulent flow in vertical round tubes based on Reynolds-averaged Navier-Stokes (RANS) equations and different models for turbulent viscosity is presented. The paper is the first part of the general analysis, the works based on using algebraic turbulence models of different complexity are considered in it. The main attention is paid to Petukhov-Medvetskaya and Popov et al. models. They were developed especially for simulating heat transfer in tubes of the coolants with significantly variable properties (droplet liquids, gases, SCP fluids) under heating and cooling conditions. These predictions were verified on the entire reliable experimental data base. It is shown that in the case of turbulent flow in vertical round tubes these models make it possible predicting heat transfer and hydraulic resistance characteristics of SCP flows that agree well with the existed reliable experimental data on normal and certain modes of deteriorated heat transfer, if significant influence of buoyancy and radical flow restructuring are absent. For the more complicated cases than a flow in round vertical tubes, as well as for the case of rather strong buoyancy effect, more sophisticated prediction techniques must be applied. The state-of-the-art of these methods and the problems of their application are considered in the Part II of the analysis.

Turbulent flow structure and heat transfer in an inclined bubbly flow. Experimental and numerical investigation

2017 ◽  
Vol 52 (1) ◽  
pp. 115-127 ◽  
Author(s):  
A. E. Gorelikova ◽  
O. N. Kashinskii ◽  
M. A. Pakhomov ◽  
V. V. Randin ◽  
V. I. Terekhov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Numerical Investigation ◽  
Flow Structure ◽  
Bubbly Flow ◽  
Turbulent Flow Structure

On Calculating Heat Transfer and Pressure Drop of Supercritical-Pressure Coolants

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Vladimir A. Kurganov ◽  
Yuri A. Zeigarnik ◽  
Irina V. Maslakova
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Thermophysical Properties ◽  
High Heat ◽  
Supercritical Pressure ◽  
Heat Transfer Deterioration ◽  
Normal Heat ◽  
Turbulent Flow Structure ◽  
Heat Loads

Specific features of thermophysical properties of single-phase supercritical-pressure (SCP) coolants and typical ranges of their thermodynamic state that determine heat-transfer regularities are presented. A brief analysis of the existing concepts on SCP-coolants heat transfer under turbulent flow in tube is given. Typical features of normal and deteriorated heat-transfer regimes are described. The simple classification of deteriorated heat-transfer regimes at high heat loads that make it possible to distinguish the causes and appraise a degree of heat-transfer deterioration danger is proposed. The results from the studies of the hydraulic-resistance structure under the regimes of normal and deteriorated heat transfer are considered and the conditions, when a one-dimensional (1-D) (homogeneous) flow model can be used in hydraulic calculations, are revealed. Using sounding measurements data, the interrelation between heat-transfer deterioration and radical changes in the averaged turbulent flow structure due to fluid thermal acceleration and Archimedes forces effects is analyzed. The recommendations on calculating normal heat transfer with an account of refined standards on thermophysical properties of water and carbon dioxide are presented. The review and analysis of the existing criteria for forecasting heat-transfer deterioration and assessing the boundaries of the normal heat-transfer range are given, and the correlations for describing deteriorated heat transfer are presented.

Heat Transfer and Turbulent Flow Structure in Channels With Miniature V-Shaped Rib-Dimple Hybrid Structures on One Wall

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Peng Zhang ◽  
Yu Rao ◽  
Yanlin Li ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
Flow Structure ◽  
Pressure Loss ◽  
Numerical Study ◽  
Hybrid Structures ◽  
Numerical Computations ◽  
Turbulent Flow Structure ◽  
Near Wall

An experimental and numerical study has been conducted on heat transfer and turbulent flow structure in channels with novel hybrid structures with miniature V-shaped ribs and dimples on one wall. One miniature V-shaped rib was arranged immediately upstream each individual dimple to form the hybrid structure, which aims at inducing additional near-wall secondary flow interacting with the dimple vortex flow and further improving the heat transfer. Steady-state convective heat transfer experiments were done to obtain the heat transfer and pressure loss of the turbulent flow over the surfaces with the miniature V rib-dimples for the Reynolds numbers from 18,700 to 60,000. In addition, the turbulent flow structure in the V rib-dimpled channels has been predicted by carrying out numerical computations. The experimental results indicated that the overall heat transfer enhancement of the miniature V rib-dimpled channels can be increased by up to about 60.0% compared with the counterpart of the dimpled only channel, and by about 23.0% compared with the counterpart of the miniature V ribbed only channel. The miniature V ribs showed appreciable effects on the heat transfer and pressure loss characteristics for the turbulent flow over the V rib-dimpled surfaces. The numerical computations showed that the miniature V rib upstream each dimple produced strong near-wall downwashing secondary flow, which significantly changed the flow patterns and intensified the turbulent flow mixing inside and outside the dimple and above the surrounding wall. These unique near-wall flow characteristics generated a significant heat transfer improvement in both the magnitude and the uniformity.

scholarly journals Experimental research of turbulent flow frequency spectra

2020 ◽  
Vol 12 (2) ◽  
pp. 87-97
Author(s):  
Viacheslav KRAEV
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbulent Flow ◽  
Flow Structure ◽  
Experimental Research ◽  
Gas Flow ◽  
Turbulent Structure ◽  
Hydrodynamic Process ◽  
Frequency Spectra ◽  
Isothermal Conditions

Hydraulic and heat transfer processes play a very important role in the design and prototyping of aerospace technology. In most cases this technique works under non-isothermal conditions. Non-isothermal conditions may significantly affect heat transfer and hydrodynamic process. Fundamental research of Non-isothermal turbulent flow is required for further engineering modeling. Models for unsteady processes calculation must be based on fundamental turbulent structure research. Moscow Aviation Institute National Research University (MAI) has been building non-isothermal turbulent flow structures since 1989. An experimental facility was designed to provide gas flow heating. Experimental data of a turbulent gas flow structure in isothermal and non-isothermal conditions are presented. The frequency spectra of axial and radial velocity pulsations are based on experimental data received. The results of experimental turbulent flow research demonstrate fundamental non-isothermal processes influence on the flow structure. The main results of non-isothermal experimental research show that there are three specific zones in turbulent flow structure: wall area, maximal turbulent structure transformation and flow core. The analysis of non-isothermal conditions influence on turbulent pulsations generation and development mechanisms is presented. The results show significant distinction in turbulent flow spectra between isothermal and non-isothermal conditions. The present paper describes a method of experimental research, methodology of data processing and non-isothermal turbulent flow spectra results.

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