Relevant bibliographies by topics / Friction factor (f)

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Friction factor (f)'

Author: Grafiati
Published: 5 June 2025
Last updated: 16 July 2025

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Journal articles on the topic "Friction factor (f)"

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Sous, Damien, Solène Déalbéra, Denis Morichon, and Héloïse Michaud. "WAVE FRICTION FACTOR OVER ROUGH SEABEDS." Coastal Engineering Proceedings, no. 38 (May 29, 2025): 3. https://doi.org/10.9753/icce.v38.currents.3.

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In the presence of large roughness, such coral reef or rocks, frictional wave dissipation is expected to play a crucial role in wave transformation, possibly dominating over depth-induced breaking dissipation (Monismith et al. 2015). The wave friction factor, f w, is a key parameter for the representation of frictional wave dissipation in phase-averaged numerical models. Based on laboratory experiments of surf zone dynamics over a series of roughness layouts, the present study aims to provide further insight on (I) the validity of the existing fwin low ranges of Ao/Kr, i.e. in the presence of large roughness, and (ii) to decipher the connection between wave frictional dissipation and the architectural structure of the seabed roughness.
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López-Silva, Maiquel, Hernández Dayma Sadami Carmenates, Nancy Delgado-Hernández, and Bereche Nataly Noelia Chunga. "Explicit pipe friction factor equations: evaluation, classification, and proposal." Revista Facultad de Ingeniería, Universidad de Antioquia, no. 111 (October 9, 2023): 38–47. https://doi.org/10.17533/udea.redin.20230928.

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The Colebrook equation has been used to estimate the friction factor (<em>f</em>) in turbulent fluids. In this regard, many equations have been proposed to eliminate the iterative process of the Colebrook equation. The goal of this article was to perform an evaluation, classification, and proposal of the friction factor for better development of hydraulic projects. In this study, Gene Expression Programming (GEP), Newton-Raphson, and Python algorithms were applied. The accuracy and model selection were performed with the Maximum Relative Error (∆<em>f/f</em>), Percentage Standard Deviation (PSD), Model Selection Criterion (MSC), and Akaike Information Criterion (AIC). Of the 30 equations evaluated, the Vatankhah equation was the most accurate and simplest to obtain the friction factor with a classification of very high, reaching a value of ∆<em>f/f</em>&lt;0.5% and 1.5&lt;PSD&lt;1.6. A new equation was formulated to obtain the explicit&nbsp;<em>f&nbsp;</em>with fast convergence and accuracy. It was concluded that the combination of GEP, error theory, and selection criteria provides a more reliable and strengthened model.
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Khan, Waseem Asghar, Muhammad Arif, Mogtaba Mohammed, et al. "Numerical and Theoretical Investigation to Estimate Darcy Friction Factor in Water Network Problem Based on Modified Chun-Hui He’s Algorithm and Applications." Mathematical Problems in Engineering 2022 (February 15, 2022): 1–11. http://dx.doi.org/10.1155/2022/8116282.

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In this work, we applied the modified Chun-Hui He’s algorithm to evaluate for estimation of flow friction factor f for value of friction factor by using Colebrook–White relation. The speedy, precise, and consistent evaluation of flow friction factor f are essential for evaluation of pressure dips and streams in complex network prototypes at distinct values of diameters of pipes. Friction factor estimated outcomes are applied in everyday engineering routine. Numerous computational systems tested for distinguishing of water pipe networks resolution, such as Hardy Cross method (HCM), Newton method (NM), and modified Newton method (MNM), are presented. As a novelty, a modified Newton method tabulated data, graphical results, and comparisons that are presented with different numerical schemes.
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Heeraman, Jatoth, Ravinder Kumar, Prem Kumar Chaurasiya, Naveen Kumar Gupta, and Dan Dobrotă. "Develop a New Correlation between Thermal Radiation and Heat Source in Dual-Tube Heat Exchanger with a Twist Ratio Insert and Dimple Configurations: An Experimental Study." Processes 11, no. 3 (2023): 860. http://dx.doi.org/10.3390/pr11030860.

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The goal of this research was to convey an outlook of heat transfer and friction factor study in experimental detail with a double-pipe heat exchanger (DPHE). In process heat transformation (HT) and friction factor(f) in a (DPHE) counter-flow with a twisted tape (TT) arrangement by dimple inserts. The grooves were a kind of concavity that enhanced thermal transfer while only slightly degrading the lower pressure. Heat transmission (HT) and friction factor(f) were investigated employing dimples and protrusions of varying diameters and a uniform diameter (D) to the diameter-to-depth ratio (D/H). The impact of using twisted tape with various dimpled diameters D = 2, 4, and 6 mm at a uniform (D/H) = 1.5, 3 and 4.5 on heat transmission and friction factor properties were discussed. The dimple diameter (D) was directly connected to the friction coefficient (f), hence the highest value of friction factor was established at (D) = 6 mm. Furthermore, the best performance of Nusselt number (Nu) and performance evaluation criteria (PEC) was determined at a diameter of D = 4 mm. As a result, dimpled twisted tape additions are an excellent and cost-effective approach to improve heat transformation in heat exchangers. With fluid as a water, lower parameters, and higher Reynolds number (Re) resulted in better thermal conditions. Thermal performance and friction factor(f) correlations were developed with regard to the geometry of the dimple diameter (D) and its ratio (D/H) and ‘Re’, and a good correspondence with the experimental data was achieved. The novel geometry caused a smaller pressure drop despite its higher convection heat transfer coefficient. The results also showed that raising the ‘Re’ and nanofluid concentration, the pressure drop increased.
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Ali Sabri Abbas and Ayad Ali Mohammed. "Enhancement Of Plate-Fin Heat Exchanger Performance with Aid of Various Types of Fin Configurations: A Review." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 99, no. 2 (2022): 48–66. http://dx.doi.org/10.37934/arfmts.99.2.4866.

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This study is a review of recent studies on heat transfer enhancement in plate fin-heat exchangers (PFHE) with plain and offset (OSF) fins. Thermal designing parameters such as the coefficient of heat transfer, Nusselt number, hydraulic diameter, Colburn factor (j), friction factor (f) and Reynold's number of PFHE was presented in this review for both straight and offset types. According to the results, by replacing plain fins into OSF, the pressure increases because of the increasing of f-factor, while there is a significant increase in Nusselt number and then the heat transfer. The j &amp; f factors, are the most essential two parameters of researching the heat exchanger that were represented as functions of Reynolds number and other geometrical parameters. At the same Reynolds number, the J-factor declines and the friction factor f increases as the fin pitch increases for the same fin height and fin thickness.
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Beans, E. W., and K. C. Masiulaniec. "Frictional Flow Properties of Coal-Oil Slurries at Low Reynolds Number." Journal of Energy Resources Technology 108, no. 3 (1986): 211–13. http://dx.doi.org/10.1115/1.3231267.

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The pipe friction factor (f) and the pressure loss coefficient for a 90-deg EL (K90) were measured for coal-oil slurries at Reynolds numbers less than 100. A range of mass fractions (0 to 0.4) was examined for a single particle distribution. The pipe friction factor correlated well with the established relationship for laminar flow (f = 64/ReD) where Reynolds number is based on slurry properties. The loss coefficient for the elbow has a similar correlation.
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Kam, Heng Keong, Wen Chiet Cheong, Chan Chin Wang, and Ying Pio Lim. "Development of Lubricants Evaluation for Different Friction Laws by Using Rigid-Plastic Finite Element Method." Advanced Materials Research 626 (December 2012): 584–88. http://dx.doi.org/10.4028/www.scientific.net/amr.626.584.

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A simulator based on rigid-plastic finite element method is developed with two common friction law: Coulomb friction law and constant shear friction law are imposed. This project is to develop a simple method to identify tribological properties of various lubricants by metal forming method. In this project, the influence of different lubricants was studied by using ring compression test. The deformation of the ring compression test was measured to obtain an experimental friction calibration curves under different lubricants. To model the friction effect, theoretical friction calibration curves for Coulomb friction law and shear friction law are generated under various parameter of μ, coefficient of friction (Coulomb friction law) and m, shear factor (constant shear friction law). The experimental and theoretical friction calibration curves were compared and the result shows corresponding. The friction of the lubricants was further verified by using a common method: pulling a block on flat surface with load sensor yields the friction force, F in the basic equation F=μN where N is the normal force. The results match the calibration curves too.
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Li, You Tang, Bo Chen, and Rui Feng Wang. "Effect of Friction on the Stress Field Strength of Gear Cracks." Key Engineering Materials 452-453 (November 2010): 493–96. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.493.

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Based on elasticity theory, the stress field and stress intensity factor of gear crack are discussed. The effect of friction coefficient and crack shape on equivalent stress, displacement at crack tip and stress intensity factor were analyzed by using general finite element software ANSYS, and the formula of stress intensity factor of gear crack was revised. The results showed that the equivalent stress, displacement at crack tip and stress intensity factor increased with the friction coefficient for the same crack. For the same f and different a/c, the front friction surface played a major role when a/B﹤0.05, and the post friction surface played a major role when a/B﹥0.05. The stress intensity factor increase at first, and then decrease with the increase of a/c.
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Lamyaa Najah Snodi. "ESTIMATION OF (Nγ) FOR STRIP AND CIRCULAR FOOTINGS USING THE METHOD OF CHARACTERISTICS". Diyala Journal of Engineering Sciences 4, № 2 (2011): 1–11. http://dx.doi.org/10.24237/djes.2011.04201.

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By using the method of characteristics (commonly referred to as the slip line method), the values of the bearing capacity factor Nγ were computed for rigid surface strip and circular footings with smooth and rough bases. The analyses of bearing capacity for vertically loaded footings using the method of characteristics have been implemented in the publicly available computer program ABC, then Nγ –values were calculated theoretically. The supporting soil is modeled as a frictional Mohr – Coulomb material. For both footings, the value of the bearing capacity factor Nγ was found to increases significantly with an increase in the angle of internal frictionf. When friction angle of soil f ≤25°, the computed values of Nγ for circular footing were found to smaller than those for strip footing and for larger values of f, the magnitude of Nγ for circular footing were greater than those for strip footing for both smooth and rough base of footings. On the other hand, the magnitude of Nγ for rough footings was seen be higher than for a footings with smooth base. The obtained results were compared with those available in the literature, and reasonable agreements were observed.
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Eiamsa-ard, S., and P. Promthaisong. "Counter-rotation vortex flows and heat transfer mechanisms in a V-spirally-corrugated tube." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 233, no. 7 (2019): 928–52. http://dx.doi.org/10.1177/0957650919829367.

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The flow and heat transfer behavior of newly designed V-corrugated tubes with various numbers of starts ( N = 2, 3, 4, and 5), depth ratios ( DR = 0.02–0.14), and pitch ratios ( PR = 1.0–2.0) were studied in the turbulent flow region (5000 ≤ Re ≤ 20,000). The friction factor ( f), friction factor ratio ( f/ f0), Nusselt number ( Nu), Nusselt number ratio ( Nu/ Nu0), and thermal enhancement factor ( TEF) values are reported. The computational results indicate that the conventional spirally-corrugated tube create swirl flows while V-corrugated tubes generate a counter-rotating vortex flow that impinges upon the lower zone of the tubes and enhances fluid transfer between tube core and near-wall regions. The results also show that the f, Nu, f/ f0, Nu/ Nu0 monotonically increase with decreasing PR, increasing DR and N, while the TEF is dependent on a tradeoff between f/ f0 and Nu/ Nu0. Over the studied range, the f/ f0, Nu/ Nu0, and TEF were in the ranges of 1.36–43.82, 1.00–5.35, and 0.80–2.11, respectively. The maximum TEF, 2.11, was achieved with a V-corrugated tube with an N of 4, DR of 0.06, and PR of 2.0 at Re = 5000.
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Dissertations / Theses on the topic "Friction factor (f)"

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Moraes, Alisson Gomes de. "Entropia máxima na modelação do fator de atrito (f) de escoamento forçado." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3147/tde-11082010-155259/.

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Esta tese apresenta um desenvolvimento do fator de atrito (f) para escoamentos incompressíveis. O desenvolvimento é baseado no modelo clássico de Colebrook-White e no recente modelo da Entropia Máxima. Este desenvolvimento pode ser considerado como um modelo conceitual, porém não completamente, por causa do relacionamento entre o número de Reynolds (Re) e o parâmetro de entropia (M) determinado através de ajustes numéricos realizados com bons dados experimentais. Quatro algoritmos de cálculo foram criados para simplificar a aplicação do modelo, evidenciando sua eficácia e a eficiência.<br>This thesis presents a development of friction factor (f) for incompressible pipe flow calculation. The development is based on the classical Colebrook-White model and on the recent maximum entropy model. The development cam be considered as a conceptual one, but not completely, because the relationship that links the Reynolds number (Re) to the entropy parameter (M) was determined by numerical fitting on accurate but experimental data. Four calculation algorithms were produced to simplify the model applications, evidencing efficiency and effectiveness.
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Book chapters on the topic "Friction factor (f)"

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Kepekçi, Haydar. "CFD Analysis of the Influence of Twisted Tape Width and Thickness on Flow Characteristics in Pipe Flow." In Doğanın Ritmi, Enerjinin Dönüşümü, Üretimin Gücü (I. Ulusal Enerji Dönüşümü ve Sürdürülebilirlik Konferansı). İstanbul Gedik Üniversitesi, 2025. https://doi.org/10.61150/gedikyay.250305.

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This study investigates the impact of twisted tape geometry on heat transfer performance in pipe flow, focusing on width ratio, thickness, and flow velocity variations. A 25 mm diameter and 1-meter-long pipe were utilized, with water as the working fluid. The analyses considered flow velocities of 0.05 m/s and 0.2 m/s, twisted tape width ratios (20%, 40%, 80%), and thicknesses (0.5 mm, 1 mm, 2 mm). Key parameters such as Reynolds number (Re), Nusselt number (Nu), friction factor (f), and pressure drop (ΔP) were calculated. The results revealed that increasing the width ratio and thickness of the twisted tape significantly influenced the hydraulic diameter, altering the Re and Nu values. Higher width ratios improved heat transfer but increased friction and pressure loss. Similarly, thicker twisted tapes elevated flow resistance, affecting pressure loss and heat transfer performance. At higher flow velocities, turbulent flow enhanced heat transfer, reflected by increased Nu, though at the expense of friction and pressure losses. Baseline comparisons without twisted tape showed significantly lower heat transfer performance. These findings highlight the critical role of optimized twisted tape design in balancing heat transfer efficiency and pressure loss for improved system performance.
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"F FOR FAKE? FRICTION OVER FACTION." In Understanding Television. Routledge, 2005. http://dx.doi.org/10.4324/9780203976258-11.

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Sridhar, W., D. Srinivasa Rao, G. Dharmaiah, and V. Sujatha. "ALIGNED MAGNETIC FIELD-ENHANCED MHD MIXED CONVECTION AND HEAT TRANSFER ON A MOVING INCLINED POROUS SURFACE." In Futuristic Trends in Contemporary Mathematics & Applications Volume 3 Book 3. Iterative International Publisher, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bfcm3p4ch1.

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The primary objective of this study is to investigate the combined effects of magnetohydrodynamic (MHD) mixed convection flow along with heat transfer on an inclined permeable sheet in motion, subjected to an aligned magnetic field. To attain this goal, precise solutions for the partial differential equations (PDEs) are derived using perturbation techniques. The research explores the impact of several factors, including radiation thermo, chemical reaction, Hall current and the aligned magnetic field. Notably, it is noted that higher values of the Schmidt number (Sc) and the parameter γ lead to a reduction in fluid concentration. Conversely, elevated values of parameters ϕ, Prandtl number (Pr), and the mixed convection parameter (F) result in a decrease in temperature. The velocity of the fluid is found to increase with higher values of the Grashof numbers (Gr), Görtler numbers (Gc), thermal buoyancy parameter (α), mixed convection parameter (F), and the permeability parameter (K). On the contrary, the velocity decreases when parameters of non-dimentional such as the Hartmann number (M), Sc, Pr, ξ, power-law index (m), and ϕ are increased. Further analysis reveals that the Sherwood number experiences a decline with increasing Sc and γ values. Conversely, the Nusselt number rises as the parameters F, ϕ, and Pr increase. Additionally, the study shows that an increase in the permeability parameter (K), Gr, and Gc results in a higher skin-friction coefficient, whereas an increase in parameters M, α, F, Sc, m, and ξ leads to a decrease in the skin-friction coefficient. To validate the findings, graphs are generated and compared with the calculated results. In summary, the study sheds light on the interplay between mixed convection, heat transfer, MHD effects, and aligned magnetic fields in a porous medium, providing valuable insights into the intricate fluid dynamics and thermal behavior.
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Conference papers on the topic "Friction factor (f)"

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Ridwan, Sandra Mayang Dika, Nasaruddin Salam, Rustan Tarakka, and Muhammad Ihsan Mukrim. "Experimental Study of Flow Characteristics and Changes in Density Concentration in Two-Phase (Liquid-Solid) Fluid Systems." In International Conference on Research in Engineering and Science Technology (IC-REST) 2023. Trans Tech Publications Ltd, 2025. https://doi.org/10.4028/p-v5z9cz.

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Indonesia is a country prone to hydrological disasters, with high potentials to mud flows in some areas. The mud flows need to be channeled to the appropriate place, and the piping system is one of the best alternatives. Through this research, the analysis of flow characteristics and changes in the density concentration in two-phase (liquid-solid) fluid systems is presented. One-inch diameter transparent PVC pipe was used as the test pipe. The pressure drop, experimental friction factor, and Reynolds number on the experimental variables show an interesting relation between the variables. At 10% ratio of liquid-solid discharge, the flow discharge ranges from 0.00000800 m³/s to 0.00001817 m³/s, while at 100% ratio, the discharge reaches 0.00002133 m³/s. The ratios of liquid-solid discharge ratio of 10% to 100% have influences on increasing pressure reduction (∆P). At increasing density from 1000 to 1010 (at mixture ratios of 10% to 20%), the pressure drop (∆P) also tends to increase. At 10%, the f value ranges from 0.0005004 to 0.0011364, where the experimental friction factor tends to be lower than the theoretical friction factor.
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Haidar, Ahmad, and Jose Palacios. "Experimental Model Validation of a Passive Balancing Device for Supercritical Helicopter Driveshafts." In Vertical Flight Society 72nd Annual Forum & Technology Display. The Vertical Flight Society, 2016. http://dx.doi.org/10.4050/f-0072-2016-11565.

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A system of passive balancing devices could potentially be used to suppress vibrations in helicopter tailrotor driveshafts. Passive balancing devices for rotary shafts consist of masses restricted by concentric guides about the shaft axis. At supercritical shaft speeds, the balancing masses automatically adjust to counter imbalance due to uneven load distribution. The problem is highly nonlinear and requires comprehensive modeling to achieve satisfactory prediction of the balancing behavior. A frequency-scaled tailrotor driveshaft test rig was fabricated to test the performance of a passive balancing device and to validate a comprehensive model. The model includes balancing mass collisions and balancing mass interaction with the balancer track through friction. Experimentally, the passive balancing device on average reduced driveshaft transverse vibrations by 62% at steady-state. Models available in the literature predicted vibration amplitudes to within 68% of the experimental values. The new balancing model improved the prediction of shaft vibration amplitudes by a factor of 3.9 when compared to published models (18% vs. 68%). This suggests that friction and mass collisions cannot be ignored in passive balancer modeling and that passive balancing is a viable solution for suppressing driveshaft vibrations.
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Chavez, Andrea, Jason Fetty, Jesse Meisterling, and Treven Baker. "Bringing Direct Bolt Preload Measurement to the Aerospace Industry." In Vertical Flight Society 72nd Annual Forum & Technology Display. The Vertical Flight Society, 2016. http://dx.doi.org/10.4050/f-0072-2016-11522.

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Many helicopter components are held together with fastened joints that include threaded bolts. Bolt preload is important for keeping fastened joints from loosening or sliding. In the aerospace industry, bolt preload is typically set by applying a specified torque. Common procedures for clamping a joint include the use of a calibrated torque wrench to apply the specified torque. While a torque wrench will display the torque applied to a clamped bolt assembly, the preload (or bolt tension) must be inferred. However, a significant factor relating applied torque to the acquired bolt tension is the friction between the bolt threads and joint interface. Tension measurement techniques are available in the aerospace industry, but they are not common. A small amount of contamination or lubricant can significantly alter the torque-tension relationship. Under the Future Advanced Rotorcraft Drive Systems (FARDS) agreement, Bell Helicopter, IntellifastTM, and the Army Aviation Development Directorate (ADD) - Aviation Applied Technology Directorate (AATD) developed and tested a technology that directly measures the tension in the bolted flexure joints of a KAFLEX drive shaft coupling. The main purpose of testing was to validate bolt tension measurement to demonstrate the Technology Readiness Level (TRL) suitable for flight test. Testing performed under the FARDS agreement for this new technology included measuring the variation in bolt preload when set to a specific torque and then dynamically testing the joint to simulate flight time. Correlation was obtained between joint movement and the reduction in bolt preload. This paper summarizes the test results and shows the importance of directly measuring bolt preload in a fastened assembly to ensure joint integrity.
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Gaggioli, Richard A. "An Alternative (Preferable) Friction Factor." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13126.

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An alternative to the traditional friction factor for pipe flow is presented (φ = [R]f). For incompressible flows, the correlation of this new friction factor with Reynolds Number [R] and Relative Roughness [ε] is presented graphically, and appears much simpler and more intuitive than the Moody Diagram (or other equivalents). Moreover, relatively simple curve-fit formulas for representing φ explicitly as a function of R and ε are presented for various flow regimes, along with measures of error associated with these approximate formulas.
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Jeng, T. M., T. Y. Wu, P. L. Chen, S. F. Chang, and Y. H. Hung. "Flow Friction Behavior in Porous Channels." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80168.

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A series of experimental studies on the flow friction behavior in a rectangular channel filled with various porous metallic foam materials have been performed. The rectangular channel has a cross-sectional area 60mm × 25.4mm with a length of 60mm. The parameters and conditions of interest in the study are the Reynolds number (Re) and medium porosity/pore density (ε/PPI). The ranges of the above-mentioned parameters are: Re=2058-6736 and ε=0.7-0.93/5-40PPI. Their effects on flow friction characteristics in such porous metallic foam channels have been systematically explored. In the study, the porous flow parameters including the Darcy number (Da), inertia coefficient (CF) and Darcy friction factor (f) are investigated. The combined effects of foam porosity and Reynolds number are examined in detail. From the results, the relevant new empirical correlations of Da and CF are proposed, respectively; and a new correlation of the friction factor in terms of ε, Da and Re is presented. Besides, the results reveal that all the ratios of f/fε=1 are much greater than unity and reach the orders of around hundreds to thousands. This manifests that it needs more pumping power to maintain the same flow rate as in a hollow channel. Finally, the experimental data of f/fε=1 is correlated in the study.
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Tu, Jih-Hsing, Fangang Tseng, and Ching-Chang Chieng. "Experimental Study on Roughness Effect for Laminar Micro-Channel Gas Flow." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/mems-23866.

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Abstract Present study investigates the roughness effect on laminar gas flow for microchannels ranging from 40 to 600 μm with various roughness heights (40–82 nm) by systematical experiments. The micro-channels are manufactured by micro-machining technology and KOH anisotropic etching is employed to achieve various roughness patterns. Experimental results shows that higher product levels of Reynolds number (Reh) and friction factor (f) are obtained for microchannels of larger size and smaller relative roughness and friction factor f approaches to laminar flow theory value f0 for very smooth channel but the ratio of (f/f0) decreases as the surface roughness increases.
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Shinde, Pradeep, and Cheng-Xian Lin. "Uncertainty Analysis in Louver Fin Aluminum Heat Exchangers." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38411.

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Uncertainty estimate, although an important subject, is not carried out in a consistent way by different researchers. In this paper, the authors performed a systematic analysis to enumerate the uncertainty calculation procedure for the brazed aluminum microchannel heat exchangers with louvered fins. Using the basic method suggested by Moffat (1988), the present study elaborates the uncertainty estimation of Reynolds number, Colburn j-factor, and friction f-factor for a liquid-air brazed aluminum heat exchanger system. The important factors and their calculation procedure associated with the uncertainty analysis are discussed. The procedure is verified and the uncertainties are estimated for a standard microchannel heat exchanger configuration available in the market. The effect of the measurement variables on the uncertainty factor is illustrated in figures. The range of uncertainties for Reynolds number, Colburn j-factor and friction f-factor are examined within the investigate parameter ranges. The study provides the calculation procedures and conditions as future reference for uncertainty analysis of louver fin brazed aluminum heat exchangers, in particular. The paper also discusses uncertainty estimation for heat exchanger systems, in general.
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Wongcharee, Khwanchit, Somsak Pethkool, and Chinaruk Thianpong. "Heat Transfer Enhancement in a Double Pipe Heat Exchanger by Insertion of Propeller-Type Swirl Generators." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22427.

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This paper describes an experimental study of turbulent convective heat transfer and flow friction characteristics in a double tube heat exchanger equipped with propellers (2 blade-type). The propellers are used as the decaying swirl generators in the inner tube. The experiments were performed using the propellers with four different interval lengths (l = 1D, 2D, 3D and 4D where D is diameter of the inner tube), for the Reynolds number ranging from 5000 to 32,000, using water with temperature of 27°C and 70°C as cold and hot working fluids, respectively. The data of the tube equipped with the propellers are reported together with those of the plain tube, for comparison. The obtained results demonstrate that the heat transfer rate in term of Nusselt number (Nu) and friction factor (f) in the tube with propellers are higher than those in the plain tube at the similar operating conditions. This is due to the chaotic mixing and efficient interruption of thermal boundary layer caused by the propellers. In addition, the Nusselt number and friction factor in the tube fitted with the propellers increase as the interval length decreases. Depending on Reynolds number and interval length, Nusselt numbers and friction factors in the tube fitted with the propellers are augmented to 1.95 to 2.3 times and 5.8 to 13.2 times of those in the plain tube. In addition, the correlations of the Nusselt number (Nu) and the friction factor (f) for tube fitted with the propellers are reported and the performance evaluation to access the real benefits of using the turbulators is also determined.
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Moon, H. K., T. O’Connell, and B. Glezer. "Channel Height Effect on Heat Transfer and Friction in a Dimpled Passage." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-163.

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The heat transfer enhancement in cooling passages with dimpled (concavity imprinted) surface can be effective for use in heat exchangers and various hot section components (nozzle, blade, combustor liner, etc.), as it provides comparable heat transfer coefficients with considerably less pressure loss relative to protruding ribs. Heat transfer coefficients and friction factors were experimentally investigated in rectangular channels which had concavities (dimples) on one wall. The heat transfer coefficients were measured using a transient thermochromic liquid crystal technique. Relative channel heights (H/d) of 0.37, 0.74, 1.11 and 1.49 were investigated in a Reynolds number range from 12000 to 60000. The heat transfer enhancement (NuHD) on the dimpled wall was approximately constant at a value of 2.1 times that (Nusm) of a smooth channel over 0.37≤H/d≤1.49 in the thermally developed region. The heat transfer enhancement ratio Nu¯HD/Nusm was invariant with Reynolds number. The friction factors (f) in the aerodynamically fully developed region were consistently measured to be around 0.0412 (only 1.6 to 2.0 times that of a smooth channel). The aerodynamic entry length was comparable to that of a typical turbulent flow (Xo/Dh = 20), unlike the thermal entry length on dimpled surface which was much shorter (xo /Dh&lt;9.8). The thermal performance Nu¯HD/Nusm/f/fsm1/3≅1.75 of dimpled surface was superior to that 1.16&lt;Nu¯HD/Nusm/f/fsm1/3&lt;1.60 of continuous ribs, demonstrating that the heat transfer enhancement with concavities can be achieved with a relatively low-pressure penalty. Neither the heat transfer coefficient distribution nor the friction factor exhibited a detectable effect of the channel height within the studied relative height range (0.37≤H/d≤1.49).
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Zou, Jiang, and Xiao-Feng Peng. "Effects of Roughness on Liquid Flow Behavior in Ducts." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98143.

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Abstract:
In this paper, liquid laminar flow friction in micro/mini ducts is considered for investigating the effects of roughness. The available research in this field is briefly reviewed, and the results are comprehensively discussed. The flow behavior is theoretically analyzed in the region adjacent to rough wall, and one of roughness effects is considered equivalent to the reduction of flow cross area, which is referred to the constricted flow model. A modified formula and coefficient η are introduced to correct the reduction value of hydraulic diameter. Two important factors, the space of two neighboring roughness elements and the reattachment length, are involved in accounting for the flow cross-section reduction. Eventually, an expression of flow resistance calculation is reduced in terms of relative roughness ε/d, parameter A and Reynolds number Re. Based on the ultimate friction factor formula, the influences of relative roughness ε/d, parameter A and Reynolds number Re on friction coefficient f are discussed by figuring and comparing f variation with those parameters.
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