scholarly journals Boolean-Based Surface Procedure for the External Heat Transfer Analysis of Dams during Construction

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Yu Hu ◽  
Zheng Zuo ◽  
Qingbin Li ◽  
Yunling Duan
Keyword(s):  
Heat Transfer ◽  
External Heat ◽  
Arch Dam ◽  
Heat Transfer Analysis ◽  
High Arch Dam ◽  
Element Analysis ◽  
External Heat Transfer ◽  
Water Side ◽  
Insulation Effect ◽  
Set Up

The external heat transfer of dams during construction is complex because such transfer is location specific and time varying. An external thermal model is developed in this paper. Five types of external heat flux are considered in the mathematical model: air-side convection, electromagnetic radiation, absorbed solar input, water-side convection, and surface insulation effect. A method for extracting and classifying the external surfaces of dams on the basis of Boolean operations is proposed. Heat transfer conditions can be automatically set up for each step according to the proposed method, and the method can be used as a preprocessing facility for finite element analysis. A 285 m high arch dam in Southwest China is examined as a study case. The model is implemented and found to correctly identify different types of external surfaces. Simulation result agrees well with the monitored temperatures.

Experimental Study of Surface Roughness Effects on a Turbine Airfoil in a Linear Cascade: Part I—External Heat Transfer

2010 ◽  
Author(s):  
M. Lorenz ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Surface Roughness ◽  
Rough Surfaces ◽  
External Heat ◽  
Roughness Height ◽  
Heat Transfer Analysis ◽  
Roughness Effects ◽  
External Heat Transfer

The present experimental study is part of a comprehensive heat transfer analysis on a highly loaded low pressure turbine blade and endwall with varying surface roughness. Whereas a former paper [1] focused on full span heat transfer of a smooth airfoil and surface roughness effects on the endwall, in this work further measurements at the airfoil midspan with different deterministic surface roughness are considered. Part I investigates the external heat transfer enhancement due to rough surfaces whereas part II focuses on surface roughness effects on aerodynamic losses. A set of different arrays of deterministic roughness is investigated in these experiments, varying the height and eccentricity of the roughness elements, showing the combined influence of roughness height and anisotropy of the rough surfaces on laminar to turbulent transition and the turbulent boundary layer as well as boundary layer separation on the pressure and suction side. It is shown that — besides the known effect of roughness height — eccentricity of roughness plays a major role in the onset of transition and the turbulent heat transfer. The experiments are conducted at several free-stream turbulence levels (Tu1 = 1.4% to 10.1%) and different Reynolds numbers.

Measurement of the parameters of external heat transfer by dilatometry

1977 ◽  
Vol 33 (1) ◽  
pp. 825-827
Author(s):  
V. S. Batalov ◽  
V. S. Batmanov ◽  
Yu. S. Grigor'ev ◽  
A. N. Perminov
Keyword(s):  
Heat Transfer ◽  
External Heat ◽  
External Heat Transfer

scholarly journals INFLUENCE OF SURFACE HEATING TEMPERATURE ON EXTERNAL HEAT-EXCHANGE IN WET VIBRO-FLUIDIZED BED

2018 ◽  
Vol 59 (5) ◽  
pp. 77
Author(s):  
Boris G. Sapozhnikov ◽  
Anastasiya M. Gorbunova ◽  
Yuliya O. Zelenkova ◽  
Nina P. Shiryaeva
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Fluidized Bed ◽  
Heating Temperature ◽  
Heating Surface ◽  
External Heat ◽  
Porous Particles ◽  
External Heat Transfer

Experimental data are given on the influence of the temperature of the heating surface, placed to a wet vibro-fluidized bed of non-porous particles, and higher that the saturation temperatures on the external heat-transfer coefficient at conductive supply of the heat.

scholarly journals Effect of Discrete Surface Disturbances on Vane External Heat Transfer

1997 ◽  
Author(s):  
R. S. Bunker
Keyword(s):  
Heat Transfer ◽  
Turbulence Intensity ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Suction Side ◽  
External Heat ◽  
Freestream Turbulence ◽  
External Heat Transfer ◽  
Enhancement Factors ◽  
Surface Disturbances

A transonic linear vane cascade has been utilized to assess the effects of localized surface disturbances on airfoil external heat transfer coefficient distributions, such as those which may be created by the spallation of thermal barrier coatings. The cascade operates at an overall pressure ratio of 1.86, with an inlet total pressure of about 5 atm. Cascade Reynolds numbers based on axial chord length and exit velocity range from 2.2 to 4.8 · 106. Surface disturbances are modeled with the use of narrow trip strips glued onto the surface at selected locations, such that sharp forward facing steps are presented to the boundary layer. Surface locations investigated include the near leading edge region on either side of the stagnation point, the midchord region of the pressure side, and the high curvature region of the suction side. Heat transfer enhancement factors are obtained for disturbances with engine representative height-to-momentum thickness ratios, as a function of Reynolds number. Enhancement factors are compared for both smooth and rough airfoil surfaces with added disturbances, as well as low and high freestream turbulence intensity. Results show that leading edge heat transfer is dominated by freestream turbulence intensity effects, such that enhancements of nearly 50% at low turbulence levels are reduced to about 10% at elevated turbulence levels. Both pressure and suction side enhancement factors are dominated by surface roughness caused effects, with large enhancements for smooth surfaces being drastically reduced for roughened surfaces.

An Experimental Study of Turbine Vane Heat Transfer With Leading Edge and Downstream Film Cooling

1990 ◽  
Vol 112 (3) ◽  
pp. 477-487 ◽  
Author(s):  
N. V. Nirmalan ◽  
L. D. Hylton
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Leading Edge ◽  
External Heat ◽  
Gas Temperature ◽  
Temperature Ratio ◽  
External Heat Transfer ◽  
Turbine Vane

This paper presents the effects of downstream film cooling, with and without leading edge showerhead film cooling, on turbine vane external heat transfer. Steady-state experimental measurements were made in a three-vane, linear, two-dimensional cascade. The principal independent parameters—Mach number, Reynolds number, turbulence, wall-to-gas temperature ratio, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio—were maintained over ranges consistent with actual engine conditions. The test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, coolant-to-gas temperature ratio, and coolant-to-gas pressure ratio. The vane external heat transfer data obtained in this program indicate that considerable cooling benefits can be achieved by utilizing downstream film cooling. The downstream film cooling process was shown to be a complex interaction of two competing mechanisms. The thermal dilution effect, associated with the injection of relatively cold fluid, results in a decrease in the heat transfer to the airfoil. Conversely, the turbulence augmentation, produced by the injection process, results in increased heat transfer to the airfoil. The data presented in this paper illustrate the interaction of these variables and should provide the airfoil designer and computational analyst with the information required to improve heat transfer design capabilities for film-cooled turbine airfoils.

scholarly journals Influence of marine kaolin mortar mixed with effective microorganism on external heat transfer

2020 ◽  
Vol 849 ◽  
pp. 012043
Author(s):  
F A Yusop ◽  
A Mohamed ◽  
H M Nor ◽  
A R M Sam ◽  
N H A Khalid ◽  
...  
Keyword(s):  
Heat Transfer ◽  
External Heat ◽  
External Heat Transfer ◽  
Effective Microorganism
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