Spectral measurements of turbulent momentum transfer in fully developed pipe flow

1973 ◽  
Vol 61 (1) ◽  
pp. 173-186 ◽  
Author(s):  
K. Bremhorst ◽  
T. B. Walker
Keyword(s):  
Momentum Transfer ◽  
Pipe Flow ◽  
Negative Transfer ◽  
Turbulent Heat Transfer ◽  
Wall Region ◽  
Turbulent Heat ◽  
Spectral Measurements ◽  
Transfer Processes ◽  
Spectral Components ◽  
Turbulent Momentum

Measurements of the spectral components of turbulent momentum transfer for fully developed pipe flow are presented. The results indicate that near the wall (y+ < 15) two types of momentum transfer processes occur. A net positive transfer takes place in the higher frequency range of the energy-containing part of the turbulence spectrum whereas a net negative transfer returns low momentum to the wall region at the lower end of the spectrum. Examination of the turbulence at various y+ shows that the significant features of the turbulence spectra scale on frequency at any given Reynolds number, thus leading to an interpretation of the flow structure which is consistent with the hydrogen-bubble visualization data of Runstadler, Kline & Reynolds (1963). The results are consistent with a flow model in which disturbances extend from the sublayer to the core of the flow. Recent turbulent heat transfer measurements are also interpreted successfully by this model.

Structure of Turbulent Velocity and Temperature Fluctuations in Fully Developed Pipe Flow

1979 ◽  
Vol 101 (1) ◽  
pp. 15-22 ◽  
Author(s):  
M. Hishida ◽  
Y. Nagano
Keyword(s):  
Pipe Flow ◽  
Dominant Role ◽  
Temperature Fluctuations ◽  
Temperature Fields ◽  
Inertial Subrange ◽  
Wall Region ◽  
Turbulent Heat ◽  
Temperature Spectrum ◽  
Axial Heat ◽  
Heat Transport Process

An experimental investigation of the turbulent structure of velocity and temperature fields has been made in fully developed pipe flow of air. In the near-wall region, the coherent quasi-ordered structure plays a dominant role in the turbulent heat transport process. The turbulent axial heat flux as well as the intensities of velocity and temperature fluctuations reach their maximums in this region, but these maximum points are different. The nondimensional intensities of velocity and temperature fluctuations are well described with the “logarithmic law” in the turbulent part of the wall region where the velocity-temperature cross-correlation coefficient is nearly constant. In the turbulent core, the velocity and temperature fluctuations are less correlated. The spectra of velocity and temperature fluctuations present −1 slope at low wavenumbers in the wall region and −5/3 slope in the inertial subrange. The temperature spectrum for the inertial-diffusive subrange indicates the −8/3 power-law.

Modeling and Simulations of Deteriorated Turbulent Heat Transfer in Wall-Heated Cylindrical Tube

2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Prasad Vegendla ◽  
Rui Hu
Keyword(s):  
Heat Transfer ◽  
Nuclear Power ◽  
Three Dimensional ◽  
Cylindrical Tube ◽  
Fluid Flows ◽  
Turbulent Heat Transfer ◽  
Wall Region ◽  
Turbulent Heat ◽  
Modeling And Simulations ◽  
Computational Fluid Dynamics Cfd

Abstract This paper discusses the modeling and simulations of deteriorated turbulent heat transfer (DTHT) for a wall-heated fluid flows, which can be observed in gas-cooled nuclear power reactors during pressurized conduction cooldown (PCC) event due to loss of force circulation flow. The DTHT regime is defined as the deterioration of normal turbulent heat transport due to increase of acceleration and buoyancy forces. The computational fluid dynamics (CFD) tools such as Nek5000 and STAR-CCM+ can help to analyze the DTHT phenomena in reactors for efficient thermal-fluid designs. Three-dimensional (3D) CFD nonisothermal modeling and simulations were performed in a wall-heated circular tube. The simulation results were validated with two different CFD tools, Nek5000 and STAR-CCM+, and validated with an experimental data. The predicted bulk temperatures were identical in both CFD tools, as expected. Good agreement between simulated results and measured data were obtained for wall temperatures along the tube axis using Nek5000. In STAR-CCM+, the under-predicted wall temperatures were mainly due to higher turbulence in the wall region. In STAR-CCM+, the predicted DTHT was over 48% at outlet when compared to inlet heat transfer values.

Theoretical Model of Wall Heat Transfer in Turbulent Flow

2011 ◽  
Vol 201-203 ◽  
pp. 171-175
Author(s):  
Wei Zheng Zhang ◽  
Xiao Liu ◽  
Chang Hu Xiang
Keyword(s):  
Heat Transfer ◽  
Theoretical Model ◽  
Turbulent Flow ◽  
Local Heat ◽  
Turbulent Heat Transfer ◽  
Wall Region ◽  
Turbulent Heat ◽  
Wall Heat Transfer ◽  
Local Heat Flux ◽  
Turbulent Wall

The turbulent flow in the near-wall region affects the wall heat transfer dominantly. The farther it is from the wall, the less effect it has. So a two-step mechanism of the turbulent wall heat transfer is released: first, the energy is transferred to the outside of the viscous sub-layer by the rolling of the micro-eddy; secondly, the energy gets to the wall by conduction. Then, a theoretical model of wall heat transfer is developed with this concept. The constant in the model is confirmed by experiment and simulation of the transient turbulent heat transfer in pipe flow. Finally, the model is used to predict the local heat flux under different conditions, and the results agree well with the experimental results as well as the simulation results.

Large Eddy Simulation of Turbulent Heat Transfer in Curved-Pipe Flow

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Changwoo Kang ◽  
Kyung-Soo Yang
Keyword(s):  
Heat Transfer ◽  
Pipe Flow ◽  
Temperature Fluctuations ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Subgrid Scale ◽  
Curved Pipe ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean

In the present investigation, turbulent heat transfer in fully developed curved-pipe flow has been studied by using large eddy simulation (LES). We consider a fully developed turbulent curved-pipe flow with axially uniform wall heat flux. The friction Reynolds number under consideration is Reτ  = 1000 based on the mean friction velocity and the pipe radius, and the Prandtl number (Pr) is 0.71. To investigate the effects of wall curvature on turbulent flow and heat transfer, we varied the nondimensionalized curvature (δ) from 0.01 to 0.1. Dynamic subgrid-scale models for turbulent subgrid-scale stresses and heat fluxes were employed to close the governing equations. To elucidate the secondary flow structures due to the pipe curvature and their effect on the heat transfer, the mean quantities and various turbulence statistics of the flow and temperature fields are presented, and compared with those of the straight-pipe flow. The friction factor and the mean Nusselt number computed in the present study are in good agreement with the experimental results currently available in the literature. We also present turbulence intensities, skewness and flatness factors of temperature fluctuations, and cross-correlations of velocity and temperature fluctuations. In addition, we report the results of an octant analysis to clarify the correlation between near-wall turbulence structures and temperature fluctuation in the vicinity of the pipe wall. Based on our results, we attempt to clarify the effects of the pipe curvature on turbulent heat transfer. Our LES provides researchers and engineers with useful data to understand the heat-transfer mechanisms in turbulent curved-pipe flow, which has numerous applications in engineering.

Characterization of Turbulent Heat Transfer in Ribbed Pipe Flow

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Changwoo Kang ◽  
Kyung-Soo Yang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pipe Flow ◽  
Temperature Fields ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Mean Flow ◽  
Transfer Enhancement ◽  
Pitch Ratio ◽  
The Mean

In the current investigation, we performed large eddy simulation (LES) of turbulent heat transfer in circular ribbed-pipe flow in order to study the effects of periodically mounted square ribs on heat transfer characteristics. The ribs were implemented on a cylindrical coordinate system by using an immersed boundary method, and dynamic subgrid-scale models were used to model Reynolds stresses and turbulent heat flux terms. A constant and uniform wall heat flux was imposed on all the solid boundaries. The Reynolds number (Re) based on the bulk velocity and pipe diameter is 24,000, and Prandtl number is fixed at Pr = 0.71. The blockage ratio (BR) based on the pipe diameter and rib height is fixed with 0.0625, while the pitch ratio based on the rib interval and rib height is varied with 2, 4, 6, 8, 10, and 18. Since the pitch ratio is the key parameter that can change flow topology, we focus on its effects on the characteristics of turbulent heat transfer. Mean flow and temperature fields are presented in the form of streamlines and contours. How the surface roughness, manifested by the wall-mounted ribs, affects the mean streamwise-velocity profile was investigated by comparing the roughness function. Local heat transfer distributions between two neighboring ribs were obtained for the pitch ratios under consideration. The flow structures related to heat transfer enhancement were identified. Friction factors and mean heat transfer enhancement factors were calculated from the mean flow and temperature fields, respectively. Furthermore, the friction and heat-transfer correlations currently available in the literature for turbulent pipe flow with surface roughness were revisited and evaluated with the LES data. A simple Nusselt number correlation is also proposed for turbulent heat transfer in ribbed pipe flow.

scholarly journals Turbulent heat transfer in a pipe flow with a pair of twisted tapes.

1991 ◽  
Vol 57 (535) ◽  
pp. 1033-1037
Author(s):  
Kunio HIJIKATA ◽  
Kazutaka MINAMI ◽  
Takao NAGASAKI ◽  
Yoshiyuki AOYAMA
Keyword(s):  
Heat Transfer ◽  
Pipe Flow ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Twisted Tapes
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