Unsteady Boundary Layers on a Flat Plate Disturbed by Periodic Wakes: Part I—Measurement of Wake-Affected Heat Transfer and Wake-Induced Transition Model

1996 ◽  
Vol 118 (2) ◽  
pp. 327-336 ◽  
Author(s):  
K. Funazaki
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Rotating Disk ◽  
Measured Data ◽  
Transition Model ◽  
Time Diagram ◽  
Test Conditions ◽  
Intermittency Factor ◽  
Unsteady Boundary Layers ◽  
Good Agreement

Measurements of wake-affected heat transfer distributions on a flat plate are made by use of a wake generator that consists of a rotating disk and several types of circular cylinder. The main purpose of this study is to construct a wake-induced transition model in terms of an intermittency factor, considering the evolution of the wake-induced turbulent region, a so-called turbulent patch in a distance–time diagram. A comparison between the proposed transition model and the measured heat transfer data reveals that the transition model yields good agreement with the measured data of all test conditions in this study.

scholarly journals Unsteady Boundary Layers on a Flat Plate Disturbed by Periodic Wakes: Part I — Measurement of Wake-Affected Heat Transfer and Wake-Induced Transition Model

1994 ◽  
Author(s):  
K. Funazaki
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Rotating Disk ◽  
Circular Cylinders ◽  
Transition Model ◽  
Time Diagram ◽  
Test Conditions ◽  
Intermittency Factor ◽  
Unsteady Boundary Layers ◽  
Good Agreement

Measurements of wake-affected heat transfer distributions on a flat plate are made by use of a wake generator that consists of a rotating disk and several types of circular cylinders. The main purpose of this study is to construct a wake-induced transition model in terms of an intermittency factor, considering the evolution of the wake-induced turbulent region, a so-called turbulent patch in a distance-time diagram. A comparison between the proposed transition model and the measured heat transfer data reveals that the transition model yields good agreement with the measured data of all test conditions in this study.

scholarly journals A Theory for Wake-Induced Transition

1989 ◽  
Author(s):  
R. E. Mayle ◽  
K. Dullenkopf
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Flow ◽  
Flat Plate ◽  
Free Stream ◽  
Plate Boundary ◽  
Transition Model ◽  
Model Comparisons ◽  
Turbulent Wakes ◽  
Flat Plate Boundary Layer

A theory for transition from laminar to turbulent flow as the result of unsteady, periodic passing of turbulent wakes in the free stream is developed using Emmons’ transition model. Comparisons made to flat plate boundary layer measurements and airfoil heat transfer measurements confirm the theory.

scholarly journals Extension of Weighted Sum of Gray Gas Data to Mathematical Simulation of Radiative Heat Transfer in a Boiler with Gas-Soot Media

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Samira Gharehkhani ◽  
Ali Nouri-Borujerdi ◽  
Salim Newaz Kazi ◽  
Hooman Yarmand
Keyword(s):  
Heat Transfer ◽  
Absorption Coefficient ◽  
Radiative Heat ◽  
Measured Data ◽  
Weighted Sum ◽  
Gas Temperature ◽  
Zone Method ◽  
Plant Site ◽  
Good Agreement ◽  
Steam Production

In this study an expression for soot absorption coefficient is introduced to extend the weighted-sum-of-gray gases data to the furnace medium containing gas-soot mixture in a utility boiler 150 MWe. Heat transfer and temperature distribution of walls and within the furnace space are predicted by zone method technique. Analyses have been done considering both cases of presence and absence of soot particles at 100% load. To validate the proposed soot absorption coefficient, the expression is coupled with the Taylor and Foster's data as well as Truelove's data for CO2-H2O mixture and the total emissivities are calculated and compared with the Truelove's parameters for 3-term and 4-term gray gases plus two soot absorption coefficients. In addition, some experiments were conducted at 100% and 75% loads to measure furnace exit gas temperature as well as the rate of steam production. The predicted results show good agreement with the measured data at the power plant site.

Wind-Related Heat Transfer Coefficient for Flat-Plate Solar Collectors

1987 ◽  
Vol 109 (2) ◽  
pp. 108-110 ◽  
Author(s):  
S. Shakerin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Separation Bubble ◽  
Convective Heat Transfer Coefficient ◽  
Leading Edge ◽  
The Heat Transfer Coefficient ◽  
Good Agreement

Experiments were performed to evaluate the convective heat transfer coefficient for a flat plate mounted in a wooden model of a roof of a building. The experiments were carried out in a closed-circuit wind tunnel and included parametric adjustments of the roof tilt and Reynolds number, based on the length of the plate. The roof tilt was set at 0, 30, 45, 60, and 90 degrees and the Reynolds number ranged from 58,000 to 250,000. A transient, one lump, thermal approach was used for heat transfer calculations. Due to a separation bubble at the leading edge of the model, i.e., the roof, at angles of attack of less than 40 degrees, the flow became turbulent after reattachment. This resulted in a higher heat transfer than previously reported in the literature. At higher angles of attack, the flow was not separated at the leading edge and remained laminar. The heat transfer coefficient for higher angles of attack, i.e., α > 40 deg, was found to be approximately independent of the angle of attack and in good agreement with the previously published results.

Unsteady Boundary Layers on a Flat Plate Disturbed by Periodic Wakes: Part II—Measurements of Unsteady Boundary Layers and Discussion

1996 ◽  
Vol 118 (2) ◽  
pp. 337-344 ◽  
Author(s):  
K. Funazaki
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Boundary Layers ◽  
Time Domain ◽  
Indirect Effect ◽  
Transition Model ◽  
Hot Wire ◽  
Turbulent Spot ◽  
Boundary Layer Interaction ◽  
Unsteady Boundary Layers

As the second part of the study, detailed hot-wire anemometry measurements of wake-affected boundary layers on the flat plate are made. These measurements are organized in order, first, to check the standpoint of the modeling of the wake-induced transition proposed in Part I, and second, to observe wake–boundary layer interaction in detail from a viewpoint of direct and indirect effect of the wake passage upon turbulent spot generation within the boundary layer, as described by Walker (1993). The validity of the presumed state of the wake-affected boundary layer in the distance–time domain, which constitutes the basis of the transition model, is confirmed to great extent. However, it is also found that the criterion for the onset of the wake-induced transition adopted in Part I should be reconsidered. Some successful attempts are therefore made to specify the transition onset.

scholarly journals Propagation of Cigarette Static Burn

2001 ◽  
Vol 19 (6) ◽  
pp. 277-287 ◽  
Author(s):  
K Miura ◽  
S Kitao ◽  
Y Egashira ◽  
N Nishiyama ◽  
K Ueyama
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Measured Data ◽  
Propagation Model ◽  
Heating Period ◽  
Front Line ◽  
Rate Determining Step ◽  
Cigarette Paper ◽  
Time Required ◽  
Good Agreement

AbstractA propagation model of cigarette static burn at the cigarette periphery is proposed. Propagation of cigarette static burn is characterized by intermittent burn of the cigarette paper. The burning rate depends on the period of flash burn of the paper and is independent of the burning width. By measuring the local temperature near the front line of the burning propagation, the rate-determining step was identified as the time required to ignite the paper. A mathematical analysis was performed by calculating the heat transfer at the periphery during the paper heating period, and it was revealed that the thermal properties of the cigarette are the dominant factors of cigarette static burn. Modeling results showed good agreement with measured data.

A Theory for Wake-Induced Transition

1990 ◽  
Vol 112 (2) ◽  
pp. 188-195 ◽  
Author(s):  
R. E. Mayle ◽  
K. Dullenkopf
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Flow ◽  
Flat Plate ◽  
Free Stream ◽  
Plate Boundary ◽  
Transition Model ◽  
Model Comparisons ◽  
Turbulent Wakes ◽  
Flat Plate Boundary Layer

A theory for transition from laminar to turbulent flow as the result of unsteady, periodic passing of turbulent wakes in the free stream is developed using Emmons’ transition model. Comparisons made to flat plate boundary layer measurements and airfoil heat transfer measurements confirm the theory.

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