Pressure, Frictional Resistance, and Flow Characteristics of the Partially Wetted Rotating Disk

1968 ◽  
Vol 90 (2) ◽  
pp. 395-404 ◽  
Author(s):  
H. N. Ketola ◽  
J. M. McGrew
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Pressure Gradient ◽  
Flow Characteristics ◽  
Frictional Resistance ◽  
Rotating Disk ◽  
Practical Applications ◽  
Stationary Wall ◽  
Spacing Ratio ◽  
Analytical Expressions

A theory of the partially wetted rotating disk is described and experimental data presented which verify the application of this theory in practical applications. Four different flow regimes may be identified according to the value of the disk Reynolds number and the spacing ratio between the disk and stationary wall. The analytical expressions for prediction of the pressure gradient developed and the frictional resistance are uniquely determined by the disk Reynolds number, spacing ratio, and the degree of wetting of the disk.

Influence of Flow Characteristics on the Discharge Coefficient of a Multiperforated Wall

2005 ◽  
Author(s):  
Jean-Louis Champion ◽  
Pasquale Di Martino ◽  
Xavier Coron
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
General Expression ◽  
Discharge Coefficient ◽  
Flow Characteristics ◽  
Coolant Flow ◽  
Asymptotic Value ◽  
Rate Of Increase ◽  
Classical Correlations

The aim of this study is to determine the discharge coefficient of a multiperforated wall sample designed by AVIO, and more precisely to show the influence of each surrounding flow (inside holes, coolant and main flows). Results obtained are compared to correlations from literature. As previously observed, it is found that the discharge coefficient is strongly dependent on the Reynolds number relative to the hole flow (Reh). The influence of the coolant flow has been proved. The comparison with classical correlations shows many differences: i) on the expected asymptotic value ii) on the rate of increase for the lowest values of Reh. This influence is not taken into account by classical correlations deduced from experiments carried out without crossflow. Based on our experiments, we determined a general expression of Cd. Experimental data are fitted with a function of type Cd = A(1−exp(−B.Reh)), where A and B are expressed as functions of the Reynolds number (Re2) of the coolant flow.

scholarly journals Characterization of the Behavior of Confined Laminar Round Jets

2012 ◽  
Author(s):  
D. Tyler Landfried ◽  
A. Jana ◽  
M. L. Kimber
Keyword(s):  
Reynolds Number ◽  
Poiseuille Flow ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Expansion Ratio ◽  
Downstream Location ◽  
Practical Applications ◽  
Free Jet ◽  
Laminar Jet ◽  
Jet Behavior

Confined laminar fluid jets have many practical applications in industry. Several examples include expansions in pipes and flow of gas into a large plenum. While much consideration has been given experimentally to heat transfer and pressure gradients within the confinement, little attention has been paid to quantify the velocity profiles and transitions between various flow behaviours. Using a finite volume CFD code, OpenFOAM ®, the Navier-Stokes equations were solved for varying expansion ratio, 1/ε = renclosure/rj, and varying Reynolds numbers. In the present analysis, Reynolds number based on the inlet jet diameter is varied from 30 to 70, well within the accepted range for laminar jet behavior. The expansion ratio, 1/ε is varied from 20–200. Of primary focus in the current study are compact correlations for the jet centreline velocity as a function of jet Reynolds number, Rej and expansion ratio. Similar functional dependences for the “linear” decay region of the jet, and the location of the stagnation point on the enclosure wall, are also investigated. These are all important features of the global flow field for the confined jet. Results suggest that initially, the flow characteristics are identical to a free jet. At some downstream location, the presence of the enclosure is felt by the jet and deviations begin to be seen from free jet behavior. This transition region continues until at a sufficiently large downstream location, the flow becomes fully developed, internal Poiseuille flow. In this paper, we analyse these transition regions and offer explanations and practical correlations to successfully predict the important flow physics that occur between free jet behavior and Poiseuille flow. Key dimensionless parameters are identified, the magnitude of which can be used to classify the flow conditions.

scholarly journals Investigating the Effect of Heterogeneous Hull Roughness on Ship Resistance Using CFD

2021 ◽  
Vol 9 (2) ◽  
pp. 202
Author(s):  
Soonseok Song ◽  
Yigit Kemal Demirel ◽  
Claire De Marco Muscat-Fenech ◽  
Tonio Sant ◽  
Diego Villa ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Reynolds Number ◽  
Shear Stress ◽  
Flow Characteristics ◽  
Cfd Simulations ◽  
Ship Resistance ◽  
Wigley Hull ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Research into the effects of hull roughness on ship resistance and propulsion is well established, however, the effect of heterogeneous hull roughness is not yet fully understood. In this study, Computational Fluid Dynamics (CFD) simulations were conducted to investigate the effect of heterogeneous hull roughness on ship resistance. The Wigley hull was modelled with various hull conditions, including homogeneous and heterogeneous hull conditions. The results were compared against existing experimental data and showed a good agreement, suggesting that the CFD approach is valid for predicting the effect of heterogeneous hull roughness on ship resistance. Furthermore, the local distributions of the wall shear stress and roughness Reynolds number on the hull surface were examined to assess the flow characteristics over the heterogeneous hull roughness.

Vorticity Shedding and Acoustic Resonance Excitation of Two Tandem Spirally Finned Cylinders in Cross-Flow

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Mohammed Alziadeh ◽  
Atef Mohany
Keyword(s):  
Reynolds Number ◽  
Strouhal Number ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Acoustic Resonance ◽  
Root Diameter ◽  
Circular Cylinders ◽  
Resonance Excitation ◽  
Equivalent Diameter ◽  
Spacing Ratio

Abstract The aeroacoustic response of two tandem spirally finned cylinders is experimentally investigated. Three different pairs of finned cylinders are studied with fin pitch-to-root diameter ratios (p/Dr) ranging between 0.37≤p/Dr≤0.74. The spiral fins are crimped similar to those used in industrial heat exchangers. The results of the finned cylinders are compared with bare, circular cylinders with a modified equivalent diameter (Deq). The spacing ratio (L/Deq) between the cylinders are kept constant at L/Deq=2.00. The Strouhal number (StDeq) of the tandem finned cylinders is found to be higher compared to the tandem bare cylinders, resulting in an earlier onset of coincidence resonance. Moreover, unlike the tandem bare cylinders, the Strouhal number of the finned cylinders did not depend on the Reynolds number, suggesting that the flow characteristics around the finned cylinders are unaffected by Reynolds number. Only the tandem finned cylinders with the lowest fin pitch-to-root diameter ratio (p/Dr=0.37) were capable of exciting precoincidence acoustic resonance. The precoincidence resonance mechanism is similar to that observed in in-line tube bundles.

scholarly journals Numerical Computations for Flow Patterns and Force Statistics of Three Rectangular Cylinders

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Hamid Rahman ◽  
Shams-ul-Islam ◽  
Waqas Sarwar Abbasi ◽  
Raheela Manzoor ◽  
Fazle Amin ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Vortex Shedding ◽  
Lift Coefficient ◽  
Flow Characteristics ◽  
Drag And Lift Coefficients ◽  
Aspect Ratios ◽  
Spacing Ratio ◽  
Drag And Lift ◽  
Rectangular Cylinders

In this work, numerical simulations are performed in order to study the effects of aspect ratio (AR) and Reynolds number (Re) on flow characteristics of three side-by-side rectangular cylinders for fixed spacing ratio ( g ), using the lattice Boltzmann method (LBM). The Reynolds number varies within the range 60 ≤ Re ≤ 180, aspect ratio is between 0.25 and 4, and spacing ratio is fixed at g  = 1.5. The flow structure mechanism behind the cylinders is analyzed in terms of vorticity contour visualization, time-trace analysis of drag and lift coefficients, power spectrum analysis of lift coefficient and variations of mean drag coefficient, and Strouhal number. For different combinations of AR and Re, the flow is characterized into regular, irregular, and symmetric vortex shedding. In regular and symmetric vortex shedding the drag and lift coefficients vary smoothly while reverse trend occurs in irregular vortex shedding. At small AR, each cylinder experiences higher magnitude drag force as compared to intermediate and large aspect ratios. The vortex shedding frequency was found to be smaller at smaller AR and increased with increment in AR.

scholarly journals Comparison of velocity distribution in turbulent diffusion jet given by the integral model and code CFD FLUENT 6.0

2005 ◽  
Vol 27 (1) ◽  
pp. 51-58
Author(s):  
Bui Van Ga ◽  
Pham Thi Kim Loan ◽  
Nhan Hong Quang
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Velocity Distribution ◽  
Turbulent Diffusion ◽  
Integral Model ◽  
Practical Applications ◽  
Cpu Time ◽  
Exit Nozzle ◽  
Time Calculation ◽  
The Difference

Integral model is simple in utilization, low in CPU time calculation, suitable for a lot of practical applications of turbulent diffusion jet. However the assessment of accuracy of the model should be carried out by experimental data and by results of available multidirectional codes. The present paper shows the comparison of velocity profiles given by the integral model and the CFD FLUENT 6.0 Code. The difference in results given by the two models is lower than 10% when Reynolds number at the exit nozzle below 5000.

Diagnostics of metal samples using the results of experimental and theoretical study of positively charged microparticles formed upon sample destruction

2018 ◽  
Vol 84 (10) ◽  
pp. 23-28
Author(s):  
D. A. Golentsov ◽  
A. G. Gulin ◽  
Vladimir A. Likhter ◽  
K. E. Ulybyshev
Keyword(s):  
Experimental Data ◽  
Early Stage ◽  
Experimental Studies ◽  
Material Model ◽  
Total Charge ◽  
Cross Sectional ◽  
Practical Applications ◽  
Mechanical And Electrical Properties ◽  
Order Of Magnitude ◽  
Using Data

Destruction of bodies is accompanied by formation of both large and microscopic fragments. Numerous experiments on the rupture of different samples show that those fragments carry a positive electric charge. his phenomenon is of interest from the viewpoint of its potential application to contactless diagnostics of the early stage of destruction of the elements in various technical devices. However, the lack of understanding the nature of this phenomenon restricts the possibility of its practical applications. Experimental studies were carried out using an apparatus that allowed direct measurements of the total charge of the microparticles formed upon sample rupture and determination of their size and quantity. The results of rupture tests of duralumin and electrical steel showed that the size of microparticles is several tens of microns, the particle charge per particle is on the order of 10–14 C, and their amount can be estimated as the ratio of the cross-sectional area of the sample at the point of discontinuity to the square of the microparticle size. A model of charge formation on the microparticles is developed proceeding from the experimental data and current concept of the electron gas in metals. The model makes it possible to determine the charge of the microparticle using data on the particle size and mechanical and electrical properties of the material. Model estimates of the total charge of particles show order-of-magnitude agreement with the experimental data.

Study on the Flow Characteristics of Shengli Oilfield Super Heavy Oil

2017 ◽  
Vol 10 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Wang Shou-long ◽  
Li Ai-fen ◽  
Peng Rui-gang ◽  
Yu Miao ◽  
Fu Shuai-shi
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Heavy Oil ◽  
Flow Characteristics ◽  
Fluid Viscosity ◽  
Linear Flow ◽  
Start Up ◽  
Non Linear ◽  
Core Permeability ◽  
Velocity Pressure

Objective:The rheological properties of oil severely affect the determination of percolation theory, development program, production technology and oil-gathering and transferring process, especially for super heavy oil reservoirs. This paper illustrated the basic seepage morphology of super heavy oil in micro pores based on its rheological characteristics.Methods:The non-linear flow law and start-up pressure gradient of super heavy oil under irreducible water saturation at different temperatures were performed with different permeable sand packs. Meanwhile, the empirical formulas between start-up pressure gradient, the parameters describing the velocity-pressure drop curve and the ratio of gas permeability of a core to fluid viscosity were established.Results:The results demonstrate that temperature and core permeability have significant effect on the non-linear flow characteristics of super heavy oil. The relationship between start-up pressure gradient of oil, the parameters representing the velocity-pressure drop curve and the ratio of core permeability to fluid viscosity could be described as a power function.Conclusion:Above all, the quantitative description of the seepage law of super heavy oil reservoir was proposed in this paper, and finally the empirical diagram for determining the minimum and maximum start-up pressure of heavy oil with different viscosity in different permeable formations was obtained.

scholarly journals Fibre-induced drag reduction

2008 ◽  
Vol 602 ◽  
pp. 209-218 ◽  
Author(s):  
J. J. J. GILLISSEN ◽  
B. J. BOERSMA ◽  
P. H. MORTENSEN ◽  
H. I. ANDERSSON
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Elastic Layer ◽  
Turbulent Drag Reduction ◽  
Rigid Polymer ◽  
Fibre Concentration ◽  
Induced Drag ◽  
Turbulent Drag

We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction is derived by adopting the concept of the elastic layer.

Liquid Jet Impingement Cooling of a Rotating Disk

1986 ◽  
Vol 108 (3) ◽  
pp. 540-546 ◽  
Author(s):  
H. J. Carper ◽  
J. J. Saavedra ◽  
T. Suwanprateep
Keyword(s):  
Reynolds Number ◽  
Average Nusselt Number ◽  
Convective Heat Transfer Coefficient ◽  
Jet Impingement ◽  
Rotating Disk ◽  
Liquid Jet ◽  
Flow Rates ◽  
Impingement Cooling ◽  
Angular Velocities ◽  
Jet Nozzle

Results are presented from an experimental study conducted to determine the average convective heat transfer coefficient for the side of a rotating disk, with an approximately uniform surface temperature, cooled by a single liquid jet of oil impinging normal to the surface. Tests were conducted over a range of jet flow rates, jet temperatures, jet radial positions, and disk angular velocities with various combinations of three jet nozzle and disk diameters. Correlations are presented that relate the average Nusselt number to rotational Reynolds number, jet Reynolds number, jet Prandtl number, and dimensionless jet radial position.

Sign in / Sign up

Export Citation Format

Share Document