scholarly journals The Numerical Investigation of the Heat Transport in the Nanofluids under the Impacts of Magnetic Field: Applications in Industrial Zone

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Adnan ◽  
Umar Khan ◽  
Naveed Ahmed ◽  
Syed Tauseef Mohyud-Din ◽  
Ilyas Khan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Shear Stresses ◽  
Fluid Temperature ◽  
Science Literature ◽  
Electrically Conducting ◽  
Flow Parameters ◽  
Flow Investigation ◽  
Prandtl Numbers

The dynamics of the nanofluid flow between two plates that are placed parallel to each other is of huge interest due to its numerous applications in different industries. Keeping in view the significance of such flow, investigation of the heat transfer in the Cu-H2O nanofluid is conducted between parallel rotating plates. For more significant results of the study, the squeezing effects are incorporated over the plates that are electrically conducting. The nondimensional flow model is then treated analytically (VPM), and the results are sketched against the preeminent flow parameters. The remarkable heat transfer in the nanofluid is noticed against the Eckert and Prandtl numbers, whereas the Lorentz forces oppose the fluid temperature. Furthermore, the shear stresses at the walls drop and the local heat transfer rate rises due to increasing flow parameters. Finally, to validate the study, a comparison is made with existing available science literature and noted that the presented results are aligned with them.

scholarly journals Experimental study of the heat transfer of two parallel impinging jets

2021 ◽  
Vol 2119 (1) ◽  
pp. 012029
Author(s):  
M V Philippov ◽  
I A Chokhar ◽  
V V Terekhov ◽  
V I Terekhov
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Local Heat Transfer ◽  
Turbulent Jets ◽  
Local Heat ◽  
Impinging Jets ◽  
Jet Interaction ◽  
Flow Parameters ◽  
Integral Characteristics ◽  
Integral Heat

Abstract Local and integral characteristics of heat transfer are obtained at varying the Reynolds number Re = 5500, 11000, the distance between the jets y/D = 1.8, and the distance from the jets to the surface z/D = 0.5-10 for the system of two identical impinging jets. It is found in experiments that the effect of an adjacent jet leads to enhancement of local heat transfer at large distances between the nozzles and the barrier. It is also shown that an increase in the Re number increases integral heat transfer, and, at the same time, weakens the inter-jet interaction. The paper analyzes the scenarios of the behavior of local and integral heat transfer depending on the geometric and flow parameters of the system of two circular turbulent jets.

scholarly journals Laser interferometry - Report #HT-01-2017

2021 ◽  
Author(s):  
David Naylor
Keyword(s):  
Heat Transfer ◽  
Light Beam ◽  
Three Dimensional ◽  
Local Heat Transfer ◽  
Laser Interferometry ◽  
Local Heat ◽  
Temperature Fields ◽  
Fluid Temperature ◽  
Two Dimensional ◽  
Transfer Rates

An introduction is given to the optical setup and principle of operation of classical and holographic interferometers that are used for convective he at transfer measurements. The equations for the evaluation of the temperature field are derived and methods of analysis are discussed for both two-dimensional and three-dimensional temperature fields. Emphasis is given to techniques for measuring local heat transfer rates. For two-dimensional fields, a method is presented for measuring the surface temperature gradient directly from a finite (wedge) fringe interferogram. This “direct gradient method” is shown to be most useful for the measurement of low convective heat transfer rates. For three-dimensional fields, the equations for calculating the beam-averaged local heat flux are presented. The measurement of the fluid temperature averaged along the light beam is shown to be approximate. However, an analysis is presented showing that for most cases the error associated with temperature variations in the light beam direction is small. Digital image analysis of interferograms to obtain fringe spacings is also discussed briefly.

Local Internal Impingement Heat Transfer Near a 30 and 90 Deg Row of Film Cooling Holes: Part 1 — Effect of Flow Parameters

2006 ◽  
Author(s):  
Lei Xu ◽  
Haiping Chang ◽  
Jingyang Zhang
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Local Heat Transfer ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Heat Transfer Characteristics ◽  
Flow Parameters ◽  
Section Area ◽  
Cooling Hole ◽  
Film Cooling Holes

Experimental investigations of local impingement heat transfer characteristics near a row of film cooling holes in a simulated internal midchord region of gas turbine blade have been carried out. The research of heat transfer characteristics is focused on three film cooling hole diameter area located upstream and downstream a row of film holes. There is a line of equally spaced film cooling holes whose angles are 30 or 90 degrees. When there is no impingement, the investigation about the effect of the film cooling bleed has been carried out under different cross flow Reynolds Numbers and film outflow-to-crossflow mass flux ratios based on each film cooling hole/channel section area. The results indicate that the local heat transfer near the film cooling holes is enhanced with the increase of the crossflow Reynolds Numbers and film outflow-to-crossflow mass flux ratios based on each film cooling hole/channel-section area. The local heat transfer characteristic downstream film cooling holes is better than that upstream film cooling holes. The average Nusselt number of one time diameter area downstream the row of film holes is generally 40% more than that upstream the row of film cooling holes. The place closer to the hole will have stronger heat transfer whether upstream film cooling holes or downstream film cooling holes. When there is impingement, the impinging air is provided by a single line of equally spaced jets. The spacing of the jet holes is twice that of the film cooling holes with staggered arrangements. The local heat transfer near the row of film cooling holes has been studied experimentally through changing flow parameters, such as impinging Reynolds Numbers and mass flux ratios of crossflow-to-jet based on each channel/jet hole section area etc. A great number of experimental data has been obtained. Based on this, the effects of the flow parameters on the heat transfer characteristics have been obtained qualitatively and quantitatively. It can be the important reference for accurately designing gas turbine blade.

The Influence of Including a Partially Smooth Section in the 2nd Leg of an Internally Ribbed Two Pass Cooling Channel

2006 ◽  
Author(s):  
Detlef Pape ◽  
Sean Jenkins ◽  
Jens von Wolfersdorf ◽  
Bernhard Weigand ◽  
Martin Schnieder
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Three Dimensional ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Internal Cooling ◽  
Fluid Temperature ◽  
Turbine Engine ◽  
Pressure Losses ◽  
Uniform Manner

Internal cooling schemes for blades in a gas turbine engine often are subject to compromises between increased pressure losses in return for greater levels of heat transfer required to maintain durability levels in the engine’s harsh environment. Rib configurations have been the subject of much study in past years, however these configurations are normally presumed to be used in “full-coverage” mode, meaning that the ribs are placed in the channel in a continuous and uniform manner. This study investigates the interaction between the bend effects downstream of a 180° bend, which cause higher local heat transfer, and the effect of ribs. Some of the ribs directly downstream of the 180° bend in the 2nd leg of a two pass high aspect ratio (4:1) channel were removed and the effect on heat transfer was assessed. Experimental results showed that the heat transfer level recovered quickly once ribs were encountered. As expected, some decrease in heat transfer was observed in the region where ribs were removed; however total pressure losses in the channel were also much lower. Results include detailed two-dimensional heat transfer distributions determined by the transient liquid crystal method as well as an analysis of the balance between pressure recovery and local heat transfer levels. Generally, for the accuracy of the transient liquid crystal technique in complex three-dimensional flows, strongly varying fluid temperatures present in and downstream of the bend region must be taken into account. For this study, time and position dependent fluid temperature distributions were measured to account for these effects, making it possible to obtain high quality heat transfer results in those regions.

Heat Transfer in a Radially Rotating Four-Pass Serpentine Channel With Staggered Half-V Rib Turbulators

2000 ◽  
Vol 123 (1) ◽  
pp. 39-50 ◽  
Author(s):  
G. J. Hwang ◽  
S. C. Tzeng ◽  
C. P. Mao ◽  
C. Y. Soong
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Enhancement ◽  
Serpentine Channel ◽  
Ribbed Channel ◽  
Flow Parameters ◽  
Rib Turbulators ◽  
Rib Arrangement

The present work is concerned with experimental investigation of the convective heat transfer in a radially rotating four-pass serpentine channel. Two types of staggered half-V rib turbulators are considered to examine their effects on heat transfer enhancement. The coolant air is pressurized and pre-cooled to compensate for the low rotating rate and low temperature or density difference in key parameters of thermal and flow characteristics. The geometric dimensions are fixed, whereas the ranges of the thermal and flow parameters in the present measurements are 20,000⩽Re⩽40,000,0⩽Ro⩽0.21, and Gr/Re2∼O10−2. The present results disclose the effects of the pressurized flow, rib arrangement, channel rotation, and centrifugal buoyancy on the local heat transfer in each passage of the channel. Finally, the present data are fitted on correlation equations for evaluation of local heat transfer in the rotating four-pass ribbed channel configurations considered.

A Comparison of the Transient and Heated-Coating Methods for the Measurement of Local Heat Transfer Coefficients on a Pin Fin

1989 ◽  
Vol 111 (4) ◽  
pp. 877-881 ◽  
Author(s):  
J. W. Baughn ◽  
P. T. Ireland ◽  
T. V. Jones ◽  
N. Saniei
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Uniform Heat Flux ◽  
Fluid Temperature ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Heat Transfer Coefficients ◽  
The Difference

Measurements of the local heat transfer coefficients on a pin fin (i.e., a short cylinder in crossflow) in a duct have been made using two methods, both of which employ liquid crystals to map an isotherm on the surface. The transient method uses the liquid crystal to determine the transient response of the surface temperature to a change in the fluid temperature. The local heat transfer coefficient is determined from the surface response time and the thermal properties of the substrate. The heated-coating method uses an electrically heated coating (vacuum-deposited gold in this case) to provide a uniform heat flux, while the liquid crystal is used to locate an isotherm on the surface. The two methods compare well, especially the value obtained near the center stagnation point of the pin fin where the difference in the thermal boundary condition of the two methods has little effect. They are close but differ somewhat in other regions.

scholarly journals Heat Transfer and Fluid Mechanics Measurements in Transitional Boundary Layer Flows

1985 ◽  
Vol 107 (4) ◽  
pp. 1007-1015 ◽  
Author(s):  
T. Wang ◽  
T. W. Simon ◽  
J. Buddhavarapu
Keyword(s):  
Heat Transfer ◽  
Turbulent Flows ◽  
Plate Boundary ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Shear Stresses ◽  
Boundary Layer Flows ◽  
Transfer Coefficients ◽  
Reynolds Analogy ◽  
Heat Transfer Coefficients

Experimental results are presented to document hydrodynamic and thermal development of flat-plate boundary layers undergoing natural transition. Local heat transfer coefficients, skin friction coefficients, and profiles of velocity, temperature, and Reynolds normal and shear stresses are presented. A case with no transition and transitional cases with 0.68 percent and 2.0 percent free-stream disturbance intensities were investigated. The locations of transition are consistent with earlier data. A late-laminar state with significant levels of turbulence is documented. In late-transitional and early-turbulent flows, turbulent Prandtl number and conduction layer thickness values exceed, and the Reynolds analogy factor is less than, values previously measured in fully turbulent flows.

Convective Heat Transfer in the Stagnation Zone of an Axisymmetric Upward Jet Impinging on a Stationary Flat Surface

2015 ◽  
Author(s):  
Dennis Soltis ◽  
Brian Sangeorzan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flat Surface ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Bond Number ◽  
Nozzle Diameter ◽  
Stagnation Zone ◽  
Oil Viscosity ◽  
Prandtl Numbers

Experiments were conducted to measure the local heat transfer coefficient in the stagnation zone of an upward, free oil jets impinging upon a stationary, heated flat surface. Six tube-style nozzles were used having diameters ranging from 0.864 mm to 3.073 mm. The oil viscosity ratio, based upon the nozzle and surface temperatures, varied from 0.472 to 0.903. The fluids tested included Prandtl numbers ranging from 62 to 142, and by varying the flow rate the Reynolds number ranged from 268 to 3,810. Testing demonstrated that the Reynolds number, which includes the nozzle diameter as the characteristic length, did not account properly for the effect of nozzle diameter on the heat transfer rate. Introduction of the Bond number into the Nusselt number correlation did allow a good correlation for all nozzle diameters.

Local Heat Transfer Coefficients for Condensation in Stratified Countercurrent Steam-Water Flows

1983 ◽  
Vol 105 (4) ◽  
pp. 706-712 ◽  
Author(s):  
H. J. Kim ◽  
S. G. Bankoff
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rectangular Channel ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Flow Rates ◽  
Heat Transfer Coefficients ◽  
Flow Parameters ◽  
Eddy Transport

A study of steam condensation in countercurrent stratified flow of steam and subcooled water has been carried out in a rectangular channel inclined 33 deg to the horizontal. The variables in this experiment were the inlet water and steam flow rates, and the inlet water temperature. Condensation heat transfer coefficients were determined as functions of local steam and water flow rates, and the degree of subcooling. Correlations are given for the local Nusselt number for the smooth and for the rough interface regimes, and also for the dimensionless wave amplitude. A turbulence-centered model is also developed. It is shown that better agreement with the data can be obtained if the characteristic scales in the turbulent Nusselt number and Reynolds numbers are related to measured interfacial parameters rather than the bulk flow parameters. The important effect of interfacial shear, missing in previous eddy-transport models, is thus implicitly included.

Uneven Wall Heat Flux Effect on Local Heat Transfer in Rotating Two-Pass Channels With Two Opposite Ribbed Walls

1996 ◽  
Vol 118 (4) ◽  
pp. 864-876 ◽  
Author(s):  
Shou-Shing Hsieh ◽  
Wei-Jen Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Fluid Temperature ◽  
Bulk Fluid ◽  
Aspect Ratios ◽  
Uneven Heating

The influence of rotation and uneven heating condition on the local heat transfer coefficient in rotating, two-pass rib-roughened (rib height e/DH ≈ 0.17 − 0.20; rib pitch p/e = 5) rectangular channels with cross-sectional aspect ratios of 1 and 1.5 were studied for Reynolds numbers from 5000 to 25,000 and rotation numbers from 0 to 0.6152. Regionally averaged Nusselt number variations along the duct have been determined over the trailing and leading surfaces for two pass channels. In general, Coriolis-induced secondary flows are shown to enhance local heat transfer over the trailing (leading) surface in the first (second) pass compared to a duct without rotation. Centrifugal buoyancy is shown to influence the heat transfer response with heat transfer being imposed on both leading and trailing surfaces as the wall-to-bulk fluid temperature difference is increased with other controlling parameters fixed. Results also indicate a slight decrease in heat transfer coefficient for an increase in passage aspect ratio. Results are compared with previous studies. It is found that the results agree quite well with those reported by other works for two-pass flow channels.

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