EXPERIMENTAL STUDY OF THE EFFECT OF HYDRODYNAMIC UNSTEADINESS ON A TURBULENT TUBE GAS FLOW STRUCTURE AND HEAT TRANSFER

1998 ◽  
Author(s):  
Guenrikh A. Dreitser ◽  
V. B. Bukharkin ◽  
V. M. Kraev ◽  
A. S. Neverov
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Flow Structure ◽  
Gas Flow

Flow Structure and Heat Transfer in Stagnation Flow CVD Reactor

2010 ◽  
Author(s):  
Nasir Memon ◽  
Yogesh Jaluria
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Flow Reactor ◽  
Chemical Vapor ◽  
Design Parameters ◽  
Stagnation Flow ◽  
Inlet Length ◽  
The Impact

An experimental study is undertaken to investigate the flow structure and heat transfer in a stagnation flow Chemical Vapor Deposition (CVD) reactor at atmospheric pressure. It is critical to develop models that predict flow patterns in such a reactor to achieve uniform deposition across the substrate. Free convection can negatively affect the gas flow as cold inlet gas impinges on the heated substrate, leading to vortices and disturbances in the normal flow path. This experimental research will be used to understand the buoyancy-induced and momentum-driven flow structure encountered in an impinging jet CVD reactor. Investigations are conducted for various operating and design parameters. A modified stagnation flow reactor is built where the height between the inlet and substrate is reduced when compared to a prototypical stagnation flow reactor. By operating such a reactor at certain Reynolds and Grashof numbers it is feasible to sustain smooth and vortex free flow at atmospheric pressure. The modified stagnation flow reactor is compared to other stagnation flow geometries with either a varied inlet length or varied heights between the inlet and substrate. Comparisons are made to understand the impact of such geometric changes on the flow structure and the thermal boundary layer. In addition, heat transfer correlations are obtained for the substrate temperature. Overall, the results obtained provide guidelines for curbing the effects of buoyancy and for improving the flow field to obtain greater film uniformity when operating a stagnation flow CVD reactor at atmospheric pressure.

Experimental study of heat transfer in rarefied gas flow in a circular tube with constant wall temperature

2018 ◽  
Vol 93 ◽  
pp. 326-333 ◽  
Author(s):  
Vadiraj Hemadri ◽  
G.S. Biradar ◽  
Nishant Shah ◽  
Richie Garg ◽  
U.V. Bhandarkar ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Wall Temperature ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Circular Tube ◽  
Rarefied Gas Flow ◽  
Constant Wall Temperature

scholarly journals Experimental research of incipient turbulent flow frequency spectra in hydrodynamic unsteadiness

2021 ◽  
Vol 13 (2) ◽  
pp. 91-102
Author(s):  
Viacheslav KRAEV
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Flow Structure ◽  
Experimental Research ◽  
Gas Flow ◽  
Frequency Spectra ◽  
Flow Acceleration ◽  
Aerospace Systems ◽  
Acceleration And Deceleration ◽  
Unsteady Conditions

Hydraulic and heat transfer processes play a very important role in the design and prototyping of aerospace technology. Unsteady conditions are the peculiarity of mostly aerospace systems. Flow acceleration and deceleration may significantly affect the heat transfer and hydrodynamic process in channels of aerospace systems. For unsteady process modeling, a fundamental research of unsteady hydrodynamic turbulent flow structure., Moscow Aviation Institute National Research University (MAI) has been building unsteady turbulent flow structures since 1989. An experimental facility was designed to provide gas flow acceleration and deceleration. Experimental data of a turbulent gas flow structure during flow acceleration and flow deceleration are presented. The frequency spectra of axial and radial velocity pulsations are based on experimental data. The results of experimental turbulent flow research demonstrate the fundamental hydrodynamic unsteadiness influence on the flow structure. The main results of the flow acceleration and deceleration experimental research show that there are tangible differences from the steady flow structure. The analysis of unsteady conditions influence on the turbulent pulsations generation and development mechanisms is presented. The results show the unsteady conditions influence onto turbulent vortexes disintegration tempo. The present paper describes a method of experimental research, methodology of data processing and turbulent accelerated and decelerated flow spectra results.

Nucleate Boiling Heat Transfer in Spray Cooling

1996 ◽  
Vol 118 (3) ◽  
pp. 668-671 ◽  
Author(s):  
J. Yang ◽  
L. C. Chow ◽  
M. R. Pais
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Experimental Study ◽  
Boiling Heat Transfer ◽  
Gas Flow ◽  
Nucleate Boiling ◽  
Spray Cooling ◽  
Droplet Impingement ◽  
Impingement Cooling ◽  
Nucleate Boiling Heat Transfer

An experimental study to determine the effect of liquid and secondary gas flow in droplet impingement cooling is presented. The nucleate boiling regime in particular is analyzed. A correlation to predict the Nusselt number based on the liquid film thickness is derived and compared with the experimental data.

scholarly journals Experimental Study of Near-Wall Liquid Film Outflow with Co-Current Gas Flow from Nozzle into Vacuum. 2. Flow Structure behind Nozzle

2019 ◽  
Vol 20 (3) ◽  
pp. 1-12
Author(s):  
Yuri N. Vyazov ◽  
◽  
Victor G. Prikhodko ◽  
Igor V. Yarygin ◽  
Vyacheslav N. Yarygin ◽  
...  
Keyword(s):  
Experimental Study ◽  
Liquid Film ◽  
Flow Structure ◽  
Gas Flow ◽  
Near Wall

Flow Structure and Heat Transfer in a Stagnation Flow CVD Reactor

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Nasir Memon ◽  
Yogesh Jaluria
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Flow Reactor ◽  
Chemical Vapor ◽  
Design Parameters ◽  
Stagnation Flow ◽  
Inlet Length ◽  
The Impact

An experimental study is undertaken to investigate the flow structure and heat transfer in a stagnation flow chemical vapor deposition (CVD) reactor at atmospheric pressure. It is critical to develop models that predict flow patterns in such a reactor to achieve uniform deposition across the substrate. Free convection can negatively affect the gas flow as cold inlet gas impinges on the heated substrate, leading to vortices and disturbances in the normal flow path. This experimental research will be used to understand the buoyancy-induced and momentum driven flow structure encountered in an impinging jet CVD reactor. Investigations are conducted for various operating and design parameters. A modified stagnation flow reactor is built where the height between the inlet and substrate is reduced when compared with a prototypical stagnation flow reactor. By operating such a reactor at certain Reynolds and Grashof numbers, it is feasible to sustain smooth and vortex free flow at atmospheric pressure. The modified stagnation flow reactor is compared with other stagnation flow geometries with either a varied inlet length or varied heights between the inlet and substrate. Comparisons are made to understand the impact of such geometric changes on the flow structure and the thermal boundary layer. In addition, heat transfer correlations are obtained for the substrate temperature. Overall, the results obtained provide guidelines for curbing the effects of buoyancy and for improving the flow field to obtain greater film uniformity when operating a stagnation flow CVD reactor at atmospheric pressure.

Mathematical Modelling of the Flow Structure and Heat Transfer in a Channel with a Porous Insert

2014 ◽  
Vol 1013 ◽  
pp. 257-263
Author(s):  
Oleg V. Matvienko ◽  
Aleksei Bubenchikov ◽  
Anastasiya Baigulova
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Flow Structure ◽  
Porous Layer ◽  
Gas Flow ◽  
Flow Section ◽  
Initial Flow ◽  
Porous Insert ◽  
Structural Frame ◽  
Averaged Model

The paper deals with the results of studying the flow structure and heat transfer in a cylindrical channel with a porous insert. While formulating the problem the space-averaged model of interpenetrating continuums was used. The modelled system is described by the equations of continuity, motion and thermal conductivity of a gas phase, as well as the equations of thermal conductivity for a porous backfill. The results of the research show that, due to the displacement of the gas flow from the wall region to the central part of the channel, in the initial flow section a low-temperature area is formed at the inner boundary of the porous layer. The temperature of the structural frame in the initial flow section also decreases because of its cooling by the flow displaced from the wall. In the downward flow direction heating-up of the structural frame occurs due to heat transfer from the gas flow moving in the axial zone. In addition, the structural frame performs the role of a thermal reservoir and, in turn, heats the gas flow in the porous layer.

scholarly journals UNSTEADY FRICTION AND HEAT TRANSFER IN THE INITIAL PIPELINE SECTION AT THE RESET OF THERMAL LOAD

2018 ◽  
Vol 20 (5-6) ◽  
pp. 22-28
Author(s):  
K. H. Gilfanov ◽  
N. D. Yakimov ◽  
N. Y. Minvaleev ◽  
E. G. Sheshukov ◽  
N. W. Bogdanova
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Thermal Load ◽  
Gas Flow ◽  
Cylindrical Channel ◽  
Thermal Characteristics ◽  
Boundary Layer Theory ◽  
Wall Friction ◽  
High Temperature Gas

The results of numerical and experimental study of wall friction and heat transfer in a short cylindrical channel are presented. Hydrodynamic and thermal characteristics of nonstationary high-temperature gas flow are determined. The results are summarized in the framework of boundary layer theory.

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