scholarly journals Remote Measurement of Heat Flux from Power Plant Cooling Lakes

2013 ◽  
Vol 52 (6) ◽  
pp. 1366-1378
Author(s):  
Alfred J. Garrett ◽  
Robert J. Kurzeja ◽  
Eliel Villa-Aleman ◽  
James S. Bollinger ◽  
Malcolm M. Pendergast
Keyword(s):  
Boundary Layer ◽  
Power Plant ◽  
Turbulent Boundary Layer ◽  
Correlation Coefficients ◽  
Radiation Energy ◽  
Boundary Layer Theory ◽  
Remote Measurement ◽  
Thermal Imagery ◽  
Buoyancy Driven Convection ◽  
Power Plant Cooling

AbstractLaboratory experiments have demonstrated a correlation between the rate of heat loss q″ from an experimental fluid to the air above and the standard deviation σ of the thermal variability in images of the fluid surface. These experimental results imply that q″ can be derived directly from thermal imagery by computing σ. This paper analyses thermal imagery collected over two power plant cooling lakes to determine if the same relationship exists. Turbulent boundary layer theory predicts a linear relationship between q″ and σ when both forced (wind driven) and free (buoyancy driven) convection are present. Datasets derived from ground- and helicopter-based imagery collections had correlation coefficients between σ and q″ of 0.45 and 0.76, respectively. Values of q″ computed from a function of σ and friction velocity u* derived from turbulent boundary layer theory had higher correlations with measured values of q″ (0.84 and 0.89). This research may be applicable to the problem of calculating losses of heat from the ocean to the atmosphere during high-latitude cold-air outbreaks because it does not require the information typically needed to compute sensible, evaporative, and thermal radiation energy losses to the atmosphere.

scholarly journals A Kriging-based elliptic extended anisotropic model for the turbulent boundary layer wall pressure spectrum

2018 ◽  
Vol 840 ◽  
pp. 25-55 ◽  
Author(s):  
Myriam Slama ◽  
Cédric Leblond ◽  
Pierre Sagaut
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Correlation Coefficients ◽  
Space Time ◽  
Wall Pressure ◽  
Anisotropic Model ◽  
Velocity Correlation ◽  
New Model ◽  
Wall Pressure Fluctuations

The present study addresses the computation of the wall pressure spectrum for a turbulent boundary layer flow without pressure gradient, at high Reynolds numbers, using a new model, the Kriging-based elliptic extended anisotropic model (KEEAM). A space–time solution to the Poisson equation for the wall pressure fluctuations is used. Both the turbulence–turbulence and turbulence–mean shear interactions are taken into account. It involves the mean velocity field and space–time velocity correlations which are modelled using Reynolds stresses and velocity correlation coefficients. We propose a new model, referred to as the extended anisotropic model, to evaluate the latter in all regions of the boundary layer. This model is an extension of the simplified anisotropic model of Gavin (PhD thesis, 2002, The Pennsylvania State University, University Park, PA) which was developed for the outer part of the boundary layer. It relies on a new expression for the spatial velocity correlation function and new parameters calibrated using the direct numerical simulation results of Sillero et al. (Phys. Fluids, vol. 26, 2014, 105109). Spatial correlation coefficients are related to space–time coefficients with the elliptic model of He & Zhang (Phys. Rev. E, vol. 73, 2006, 055303). The turbulent quantities necessary for the pressure computation are obtained by Reynolds-averaged Navier–Stokes solutions with a Reynolds stress turbulence model. Then, the pressure correlations are evaluated with a self-adaptive sampling strategy based on Kriging in order to reduce the computation time. The frequency and wavenumber–frequency wall pressure spectra obtained with the KEEAM agree well with empirical models developed for turbulent boundary layer flows without pressure gradient.

Study of the Cooling Wall Boundary Layer with Underfloor Supply Room

2011 ◽  
Vol 287-290 ◽  
pp. 2575-2578
Author(s):  
Xiao Hua Li ◽  
Dao Guang Lin
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Laminar Boundary Layer ◽  
Air Temperature ◽  
Boundary Layer Theory ◽  
Calculation Formula ◽  
Theory Analysis ◽  
Temperature Calculation ◽  
Wall Boundary Layer ◽  
Main Region

Based on the underground supply room properties and the boundary layer theory, this paper derived the temperature calculation formula of the laminar boundary layer and turbulent boundary layer, respectively; then discussed the mass flow calculation formula of the boundary layer; at the end experiment indicated the boundary layer definitely exits between the main region and the outside structure, whose temperature is between the air temperature of the main region and the air temperature of the wall. It validated that the theory analysis is correct.

Effect of Uncooled Inlet Length and Nozzle Convergence Angle on the Turbulent Boundary Layer and Heat Transfer in Conical Nozzles Operating With Air

1967 ◽  
Vol 89 (4) ◽  
pp. 341-350 ◽  
Author(s):  
D. R. Boldman ◽  
J. F. Schmidt ◽  
R. C. Ehlers
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Theory ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Half Angle ◽  
Inlet Length ◽  
Pipe Inlet ◽  
Peak Value

Nozzle boundary layer and heat transfer measurements are presented for nozzles having half angles of convergence of 30 and 60 deg, each operating in conjunction with a short and long uncooled pipe inlet. The long inlet, which produced a fully developed turbulent boundary layer at the nozzle entrance, did not significantly alter the nozzle heat transfer distribution relative to values obtained with the short pipe inlet. Peak heat transfer coefficients for the high convergence nozzle were nearly 40 percent higher than the peak value for the 30 deg half angle of convergence nozzle. Measured heat transfer coefficients were compared to predictions based on a boundary layer theory and a pipe flow type correlation.

A New Empirical Relationship Between The Form-Parameters H32 and H12 in Boundary Layer Theory

1962 ◽  
Vol 66 (621) ◽  
pp. 588-589 ◽  
Author(s):  
Hans Fernholz
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Velocity Profile ◽  
Skin Friction ◽  
Empirical Relationship ◽  
Boundary Layer Theory ◽  
Two Dimensional ◽  
Energy Integral ◽  
The Third ◽  
The Relationship

Provided the relationship between the form-parameters H32 and H12is known, the two-dimensional turbulent boundary layer may be calculated by means of the approximate theories of Walz and Truckenbrodt without the necessity for an explicit law for the velocity profile. This relationship H32=f(H12) introduces the influence of the velocity profiles into the calculation. It is the third empirical relationship—beside those for skin friction and dissipation— which is needed to solve the momentum and energy integral equations. The formulae or curves for H32=f(H12) which are given in published papers show considerable deviations from each other so that it was felt necessary to investigate this relationship again. Fig. 1 shows the different curves.

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