Experimental Study on the Effect of Localized Blockages on the Friction Factor of a 61-Pin Wire-Wrapped Bundle

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Mason Childs ◽  
Robert Muyshondt ◽  
Rodolfo Vaghetto ◽  
Duy Thien Nguyen ◽  
Yassin Hassan
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Flow Behavior ◽  
Fluid Pressure ◽  
Transition Flow ◽  
Flow Area ◽  
Number Range ◽  
Rod Bundle ◽  
Transition Flow Regime ◽  
Friction Factor Correlation

Abstract The thermal-hydraulic behavior of the flow in rod bundles has motivated numerous experimental and computational investigations. Previous studies have identified potential for accumulation of debris within the small subchannels of typical wire-wrapped assemblies with subsequent total or partial blockage of subchannel coolant flow. A test campaign was conducted to study the effects of localized blockages on the bundle averaged friction factor of a tightly packed wire-wrapped rod bundle. Blockages were installed within the bundle, and fluid pressure drop was measured across one wire pitch for a Reynolds number range of 500–17,200. The Darcy–Weisbach friction factor of the perturbed rod bundle geometry was compared with that of the unblocked bundle, as well as with the predictions of a well-established friction factor correlation. Differing effects based on blockage size and location for various flow regimes were studied. A number of conclusions can be made about the effects of the blockages on the friction factor, such as an increasing effect of the blockage on friction factor with an increase in Reynolds number, a change in flow behavior in the turbulent transition flow regime near Reynolds number 3000, differences in effect on friction factor for different types of subchannel blockage, and a nonlinear trend in friction factor variation with flow area impeded for edge subchannels. To this end, all data and quantified uncertainty produced in this study are made available for comparison and validation of advanced computational tools.

Heat Transfer for High Aspect Ratio Rectangular Channels in a Stationary Serpentine Passage With Turbulated and Smooth Surfaces

2013 ◽  
Author(s):  
Matthew A. Smith ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Flow Behavior ◽  
Reynolds Numbers ◽  
Hydraulic Diameter ◽  
Internal Cooling ◽  
Number Range ◽  
Aspect Ratios ◽  
Parallel Configuration

Heat transfer distributions are presented for a stationary three passage serpentine internal cooling channel for a range of engine representative Reynolds numbers. The spacing between the sidewalls of the serpentine passage is fixed and the aspect ratio (AR) is adjusted to 1:1, 1:2, and 1:6 by changing the distance between the top and bottom walls. Data are presented for aspect ratios of 1:1 and 1:6 for smooth passage walls and for aspect ratios of 1:1, 1:2, and 1:6 for passages with two surfaces turbulated. For the turbulated cases, turbulators skewed 45° to the flow are installed on the top and bottom walls. The square turbulators are arranged in an offset parallel configuration with a fixed rib pitch-to-height ratio (P/e) of 10 and a rib height-to-hydraulic diameter ratio (e/Dh) range of 0.100 to 0.058 for AR 1:1 to 1:6, respectively. The experiments span a Reynolds number range of 4,000 to 130,000 based on the passage hydraulic diameter. While this experiment utilizes a basic layout similar to previous research, it is the first to run an aspect ratio as large as 1:6, and it also pushes the Reynolds number to higher values than were previously available for the 1:2 aspect ratio. The results demonstrate that while the normalized Nusselt number for the AR 1:2 configuration changes linearly with Reynolds number up to 130,000, there is a significant change in flow behavior between Re = 25,000 and Re = 50,000 for the aspect ratio 1:6 case. This suggests that while it may be possible to interpolate between points for different flow conditions, each geometric configuration must be investigated independently. The results show the highest heat transfer and the greatest heat transfer enhancement are obtained with the AR 1:6 configuration due to greater secondary flow development for both the smooth and turbulated cases. This enhancement was particularly notable for the AR 1:6 case for Reynolds numbers at or above 50,000.

An Experimental and Analytical Study of Single-Phase Liquid Flow in a Horizontal Well

1997 ◽  
Vol 119 (1) ◽  
pp. 20-25 ◽  
Author(s):  
H. Yuan ◽  
C. Sarica ◽  
S. Miska ◽  
J. P. Brill
Keyword(s):  
Experimental Data ◽  
Friction Factor ◽  
Horizontal Well ◽  
Flow Behavior ◽  
Reynolds Numbers ◽  
Test Facility ◽  
Phase Liquid ◽  
Rate Ratios ◽  
Friction Factor Correlation ◽  
Better Than

A new test facility was designed and constructed to simulate flow in a horizontal well with a single perforation. A total of 635 tests were conducted with Reynolds numbers ranging from 5000 to 60,000 with influx to main rate ratios ranging from 1/5 to 1/100, and also for the no-influx case. The flow behavior in a single-perforation new friction expression for a single-perforation horizontal well was developed. A new simple correlation for the horizontal well friction factor was developed by applying experimental data to the general friction factor expression. The new friction factor correlation and experimental data were compared with the Asheim et al. (1992) data and model, and showed that the new correlation performed better than the Asheim et al. (1992) model.

Heat Transfer And Pressure Drop Of An Angled Discrete Turbulator At Elevated Reynolds Numbers Up To 900,000

2021 ◽  
pp. 1-29
Author(s):  
Sam Ghazi-Hesami ◽  
Dylan Wise ◽  
Keith Taylor ◽  
Peter Ireland ◽  
Étienne Robert
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Enhance Heat Transfer ◽  
Near Surface ◽  
Number Range ◽  
Smooth Channel

Abstract Turbulators are a promising avenue to enhance heat transfer in a wide variety of applications. An experimental and numerical investigation of heat transfer and pressure drop of a broken V (chevron) turbulator is presented at Reynolds numbers ranging from approximately 300,000 to 900,000 in a rectangular channel with an aspect ratio (width/height) of 1.29. The rib height is 3% of the channel hydraulic diameter while the rib spacing to rib height ratio is fixed at 10. Heat transfer measurements are performed on the flat surface between ribs using transient liquid crystal thermography. The experimental results reveal a significant increase of the heat transfer and friction factor of the ribbed surface compared to a smooth channel. Both parameters increase with Reynolds number, with a heat transfer enhancement ratio of up to 2.15 (relative to a smooth channel) and a friction factor ratio of up to 6.32 over the investigated Reynolds number range. Complementary CFD RANS (Reynolds-Averaged Navier-Stokes) simulations are performed with the κ-ω SST turbulence model in ANSYS Fluent® 17.1, and the numerical estimates are compared against the experimental data. The results reveal that the discrepancy between the experimentally measured area averaged Nusselt number and the numerical estimates increases from approximately 3% to 13% with increasing Reynolds number from 339,000 to 917,000. The numerical estimates indicate turbulators enhance heat transfer by interrupting the boundary layer as well as increasing near surface turbulent kinetic energy and mixing.

An Experimental Procedure for Determining Both the Density and Flow Rate From Pressure Drop Measurements in a Cylindrical Pipe

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
Ghislain Michaux ◽  
Olivier Vauquelin ◽  
Elsa Gauger
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Pressure Change ◽  
Gas Mixture ◽  
Gas Extraction ◽  
Cylindrical Pipe ◽  
Flow Area ◽  
Number Range ◽  
Experimental Procedure ◽  
Pressure Drops

An experimental procedure was developed for determining both the density and flow rate of a gas from measurements of pressure drops caused by an abrupt flow area contraction in a cylindrical pipe. Experiments were carried out by varying the density and flow rate of a light gas mixture of air and helium, spanning a Reynolds number range from 0.2×104 to 3.4×104. From experimental results, a procedure was then proposed for evaluating the density from pressure change measurements in the scope of light gas extraction experiments.

Friction Factor Directly From Roughness Measurements

2001 ◽  
Author(s):  
Elling Sletfjerding ◽  
Jon Steinar Gudmundsson
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Power Spectrum ◽  
Friction Factor ◽  
High Reynolds Number ◽  
Gas Flow ◽  
Relative Roughness ◽  
High Reynolds ◽  
Friction Factor Correlation ◽  
Roughness Measurements

Abstract Pressure drop experiments on natural gas flow in 150 mm pipes at 80 to 120 bar pressure and high Reynolds number were carried out for pipes smooth to rough surfaces. The roughness was measured with an accurate stylus instrument and analyzed using fractal methods. Using a similar approach to that of Nikuradse the measured friction factor was related to the measured roughness values. Taking the value of the relative roughness and dividing it by the slope of the power spectrum of the measured roughness, a greatly improved fit with the measured friction factor was obtained. Indeed, a new friction factor correlation was obtained, but now formulated in terms of direct measurement of roughness.

Friction Factor Behavior From Flat-Plate Tests of 12.15 mm Diameter Hole-Pattern Roughened Surfaces

2011 ◽  
Author(s):  
Thanesh Deva Asirvatham ◽  
Dara W. Childs ◽  
Stephen Phillips
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Friction Factor ◽  
Dynamic Pressure ◽  
Reynolds Numbers ◽  
Stagnation Temperature ◽  
Flat Plates ◽  
Number Range ◽  
Current Test ◽  
Rough Plate

A flat-plate tester is used to measure the friction-factor behavior for a hole-pattern-roughened surface facing a smooth surface with compressed air as the medium. Measurements of mass flow rate, static pressure drop and stagnation temperature are carried out and used to find a combined (stator + rotor) Fanning friction factor value. In addition, dynamic pressure measurements are made at four axial locations at the bottom of individual holes of the rough plate and at facing locations in the smooth plate. The description of the test rig and instrumentation, and the procedure of testing and calculation are explained in detail in Kheireddin in 2009 and Childs et al. in 2010. Three hole-pattern flat-plates with a hole-pattern diameter of 12.15 mm were tested having depths of 0.9, 1.9, and 2.9 mm. Tests were done with clearances at 0.254, 0.381, and 0.653 mm, and inlet pressures of 56, 70 and 84 bar for a range of pressure ratios, yielding a Reynolds-number range of 100,000 to 800,000. The effects of Reynolds number, clearance, inlet pressure, and hole depth on friction factor are studied. The data are compared to friction factor values of three hole-pattern flat-plates with 3.175 mm diameter holes with hole depths of 1.9, 2.6, and 3.302 mm tested in the same rig described by Kheireddin in 2009. The test program was initiated mainly to investigate a “friction-factor jump” phenomenon cited by Ha et al. in 1992 in test results from a flat-plate tester using facing hole-pattern plates where, at elevated values of Reynolds numbers, the friction factor began to increase steadily with increasing Reynolds numbers. Friction-factor jump was not observed in any of the current test cases.

Experimental Investigation of the Air Flow Behavior and Heat Transfer Characteristics in Microchannels With Different Channel Lengths

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Zhi Tao ◽  
Zhibing Zhu ◽  
Haiwang Li
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Critical Reynolds Number ◽  
Flow Behavior ◽  
Channel Length ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Poiseuille Number ◽  
Channel Lengths

This paper attempts to experimentally investigate the influence of channel length on the flow behavior and heat transfer characteristics in circular microchannels. The diameters of the channels were 0.4 mm and the length of them were 5 mm, 10 mm, 15 mm, and 20 mm, respectively. All experiments were performed with air and completed with Reynolds number in the range of 300–2700. Results of the experiments show that the length of microchannels has remarkable effects on the performance of flow behavior and heat transfer characteristics. Both the friction factor and Poiseuille number drop with the increase of channel length, and the experimental values are higher than the theoretical ones. Moreover, the channel length does not influence the value of critical Reynolds number. Nusselt number decrease as the increase of channel length. Larger Nusselt numbers are obtained in shorter channels. The results also indicate that in all cases, the friction factor decreases and the Poiseuille number increases with the increase of the Reynolds number. It is also observed that the value of critical Reynolds number is between 1500 and 1700 in this paper, which is lower than the value of theoretical critical Reynolds number of 2300.

Heat Transfer Performance of Titanium Oxide in Ethylene Glycol Based Nanofluids under Transition Flow

2014 ◽  
Vol 660 ◽  
pp. 684-688 ◽  
Author(s):  
Khamisah Abdul Hamid ◽  
Wan Hamzah Azmi ◽  
Rizalman Mamat ◽  
Nur Ashikin Usri
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Reynolds Number ◽  
Ethylene Glycol ◽  
Titanium Oxide ◽  
Transition Region ◽  
Constant Heat Flux ◽  
Transition Flow ◽  
Enhancement Of Heat Transfer ◽  
Number Range

The needs to improve the efficiency of coolants undeniably become one of the concerns in cooling systems technologies nowadays. Nanofluid as coolant is invented and studied where it can provide better option for users due to augmentation in properties. This study provides experimental investigation on Titanium Oxide dispersed in water and ethylene glycol mixture under transition region with Reynolds number range of 2000 < Re <10000. Three volume concentrations are used which are 0.5 %, 1.0 % and 1.5 % for heat transfer experimental investigation under working temperature of 30 °C at constant heat flux of 600 W. The Nusselt number of the nanofluid increase with the increasing of Reynolds number at 1.5 % concentration, slightly higher than based fluid. The finding on the heat transfer coefficient shows enhancement of 2.1 % achieved by Titanium Oxide nanofluid at 1.5 % volume concentration. For 0.5 % and 1.0 % concentration, no enhancement of heat transfer achieved for the fluid flow under transition region at temperature of 30 °C.

Turbulent flow in smooth and rough pipes

2007 ◽  
Vol 365 (1852) ◽  
pp. 699-714 ◽  
Author(s):  
J.J Allen ◽  
M.A Shockling ◽  
G.J Kunkel ◽  
A.J Smits
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Outer Layer ◽  
Strong Support ◽  
Reynolds Numbers ◽  
Mean Velocity ◽  
Number Range ◽  
Princeton University ◽  
Smooth Pipe ◽  
Logarithmic Region

Recent experiments at Princeton University have revealed aspects of smooth pipe flow behaviour that suggest a more complex scaling than previously noted. In particular, the pressure gradient results yield a new friction factor relationship for smooth pipes, and the velocity profiles indicate the presence of a power-law region near the wall and, for Reynolds numbers greater than about 400×10 3 ( R + >9×10 3 ), a logarithmic region further out. New experiments on a rough pipe with a honed surface finish with k rms / D =19.4×10 −6 , over a Reynolds number range of 57×10 3 –21×10 6 , show that in the transitionally rough regime this surface follows an inflectional friction factor relationship rather than the monotonic relationship given in the Moody diagram. Outer-layer scaling of the mean velocity data and streamwise turbulence intensities for the rough pipe show excellent collapse and provide strong support for Townsend's outer-layer similarity hypothesis for rough-walled flows. The streamwise rough-wall spectra also agree well with the corresponding smooth-wall data. The pipe exhibited smooth behaviour for , which supports the suggestion that the original smooth pipe was indeed hydraulically smooth for Re D ≤24×10 6 . The relationship between the velocity shift, Δ U / u τ , and the roughness Reynolds number, , has been used to generalize the form of the transition from smooth to fully rough flow for an arbitrary relative roughness k rms / D . These predictions apply for honed pipes when the separation of pipe diameter to roughness height is large, and they differ significantly from the traditional Moody curves.

Turbulent Friction Factor for a Rod Bundle in Consideration of a Subchannel Geometry

2002 ◽  
Author(s):  
Joo Hwan Park ◽  
Chang Joon Jeong ◽  
Myung Seung Yang ◽  
Dong Suk Oh
Keyword(s):  
Friction Factor ◽  
Measurement Data ◽  
Experimental Results ◽  
Flow Area ◽  
Theoretical Derivation ◽  
Turbulent Friction ◽  
Law Of The Wall ◽  
Rod Bundle ◽  
Two Parameters ◽  
Geometry Parameter

A generalized turbulent friction factor for a rod bundle was developed based on “Law of the Wall” for a tube. It was included two parameters which are one parameter of hydraulic diameter and flow area of a subchannel and rod bundle and another parameter (called geometry parameter hereinafter) of subchannel configuration and pitch-to-diameter ratio (P/D) for a single subchannel. The turbulent geometry parameter for a single subchannel has been used as a constant on the previous works but it was found to be dependent on subchannel shapes and P/D from the present work. Hence, it was modeled as a function of the subchannel shapes and P/D from 1.0 to 1.5. The turbulent geometry parameters for single subchannels were validated by the theoretical derivation of a triangular and square subchannel. Those are compared and agreed well with the previous measurement data for 4 kinds of subchannel types such as a triangular, a square, a wall and a corner subchannel. The present model of turbulent friction factor for a rod bundle included the turbulent geometry parameter has been compared with the various experimental results for circular tubes and hexagonal tubes with various rod numbers. The predicted turbulent friction factors for those rod bundles were agreed excellently with experimental results.

Sign in / Sign up

Export Citation Format

Share Document