The Steady-State and Dynamic Characteristics of a Full Circular Bearing and a Partial Arc Bearing in the Laminar and Turbulent Flow Regimes

1967 ◽  
Vol 89 (2) ◽  
pp. 143-153 ◽  
Author(s):  
F. K. Orcutt ◽  
E. B. Arwas
Keyword(s):  
Steady State ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Dynamic Characteristics ◽  
Reynolds Numbers ◽  
Operating Parameters ◽  
Design Data ◽  
Design Charts ◽  
Laminar And Turbulent Flow

The steady-state and dynamic characteristics of a full circular bearing and a centrally loaded, 100 deg, arc bearing are calculated for a range of eccentricity ratios to 0.95 and of mean Reynolds numbers to 13,300, and presented in design charts. These are compared with the measured performance of these bearings over the same ranges of the operating parameters. There is good correlation between the theoretical and test data, leading to the conclusion that the present turbulent lubrication analysis may be used to obtain general design data for self-acting bearings, operating in the superlaminar flow regime, to supplement that presently existing for laminar flow bearings.

The Steady-State and Dynamic Characteristics of the Tilting-Pad Journal Bearing in Laminar and Turbulent Flow Regimes

1967 ◽  
Vol 89 (3) ◽  
pp. 392-400 ◽  
Author(s):  
F. K. Orcutt
Keyword(s):  
Steady State ◽  
Turbulent Flow ◽  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Calculated Data ◽  
Operating Parameters ◽  
Experimental Measurements ◽  
Tilting Pad ◽  
Laminar And Turbulent Flow ◽  
Tilting Pad Journal Bearing

Calculated steady-state and dynamic characteristics are given for the four-pad, tilting-pad journal bearing with preload coefficients of 0 and 0.5 and for mean Reynolds up to 12,000. The calculated characteristics are compared with experimental measurements over the same range of operating parameters. Correlation is good, leading to the conclusion that the calculated data are effective for design analysis of rotor-bearing systems using tilting-pad bearings.

Heat transfer enhancement using second mode self-oscillating structures

2019 ◽  
Vol 30 (7) ◽  
pp. 3827-3842
Author(s):  
Samer Ali ◽  
Zein Alabidin Shami ◽  
Ali Badran ◽  
Charbel Habchi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flow Regime ◽  
Vortex Generator ◽  
Reynolds Numbers ◽  
Content Type ◽  
Laminar Flow Regime ◽  
Second Mode

Purpose In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs). Design/methodology/approach Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers. Findings For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG. Practical implications The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones. Originality/value The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

Loss Characteristics of Orifices and Nozzles

1978 ◽  
Vol 100 (3) ◽  
pp. 299-307 ◽  
Author(s):  
S. H. Alvi ◽  
K. Sridharan ◽  
N. S. Lakshmana Rao
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Discharge Coefficient ◽  
Critical Reynolds Number ◽  
Reynolds Numbers ◽  
Center Line ◽  
Laminar Regime ◽  
Variation Of Parameters ◽  
Turbulent Flow Regime

Loss characteristics of sharp-edged orifices, quadrant-edged orifices for varying edge radii, and nozzles are studied for Reynolds numbers less than 10,000 for β ratios from 0.2 to 0.8. The results may be reliably extrapolated to higher Reynolds numbers. Presentation of losses as a percentage of meter pressure differential shows that the flow can be identified into fully laminar regime, critical Reynolds number regime, relaminarization regime, and turbulent flow regime. An integrated picture of variation of parameters such as discharge coefficient, loss coefficient, settling length, pressure recovery length, and center line velocity confirms this classification.

Prognosis the Erosion-Corrosion Rates for Slurry Seawater Flow in Steel Pipeline Using Neural System

2014 ◽  
Vol 1025-1026 ◽  
pp. 355-360 ◽  
Author(s):  
Ahmed El-Shenawy ◽  
Mohamed Shehadeh
Keyword(s):  
Corrosion Rate ◽  
Turbulent Flow ◽  
Reynolds Numbers ◽  
Neural System ◽  
Time Interval ◽  
Steel Pipes ◽  
Erosion Corrosion ◽  
Laminar And Turbulent Flow ◽  
The Neural Networks ◽  
A New Technique

The work of this paper proposes a new technique for estimating and predicting erosion corrosion rate for laminar and turbulent flow in pipes. The technique depends on the neural networks Artificial Intelligent algorithms. Based on experimental results, which was applied to A 106 carbon-steel pipes, the networks are trained. Four velocities (Reynolds numbers) are used for laminar and four for turbulent regimes. The experiments also used seawater containment three different concentrations of sand. For each experiment the iron losses were measured six times in three hours’ time interval. The proposed estimating/predicting system managed to find values between the readings as well as predict the behavior of the erosion corrosion rate for extra three hours. The estimated/predicted results have been developed to find the transient zone between the Laminar and Turbulent flow regimes and investigating its effects on the erosion-corrosion behavior.

Effects of Roughness on Turbulent Flow in Microchannels and Minichannels

2008 ◽  
Author(s):  
Timothy P. Brackbill ◽  
Satish G. Kandlikar
Keyword(s):  
Experimental Study ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Roughness Parameter ◽  
Reynolds Numbers ◽  
Turbulent Regime ◽  
Roughness Effects ◽  
Relative Roughness ◽  
Roughness Elements ◽  
Moody Diagram

The effect of roughness ranging from smooth to 24% relative roughness on laminar flow has been examined in previous works by the authors. It was shown that using a constricted parameter, εFP, the laminar results were predicted well in the roughened channels ([1],[2],[3]). For the turbulent regime, Kandlikar et al. [1] proposed a modified Moody diagram by using the same set of constricted parameters, and using the modification of the Colebrook equation. A new roughness parameter εFP was shown to accurately portray the roughness effects encountered in laminar flow. In addition, a thorough look at defining surface roughness was given in Young et al. [4]. In this paper, the experimental study has been extended to cover the effects of different roughness features on pressure drop in turbulent flow and to verify the validity of the new parameter set in representing the resulting roughness effects. The range of relative roughness covered is from smooth to 10.38% relative roughness, with Reynolds numbers up to 15,000. It was found that using the same constricted parameters some unique characteristics were noted for turbulent flow over sawtooth roughness elements.

Laminar and Turbulent Flow Past a Hydrofoil Predicted by a Distributed Vorticity Method

2020 ◽  
Author(s):  
Chunlin Wu ◽  
Spyros A. Kinnas
Keyword(s):  
Turbulent Flow ◽  
Eddy Viscosity ◽  
Current Method ◽  
Reynolds Numbers ◽  
Synchronous Communication ◽  
Coupling Scheme ◽  
Computational Domain ◽  
Computationally Efficient ◽  
Flow Past ◽  
Laminar And Turbulent Flow

Abstract A distributed viscous vorticity equation (VISVE) method is presented in this work to simulate the laminar and turbulent flow past a hydrofoil. The current method is proved to be more computationally efficient and spatially compact than RANS (Reynolds-Averaged Navier-Stokes) methods since this method does not require unperturbed far-field boundary conditions, which leads to a small computational domain, a small number of mesh cells, and consequently much less simulation time. To model the turbulent flow, a synchronous coupling scheme is implemented so that the VISVE method can resolve the turbulent flow by considering the eddy viscosity in the vorticity transport equation, and the eddy viscosity is obtained by coupling VISVE with the existing turbulence model of OpenFOAM, via synchronous communication. The proposed VISVE method is applied to simulate both the laminar flow at moderate Reynolds numbers and turbulent flow at high Reynolds numbers past a hydrofoil. The velocity and vorticity calculated by the coupling method agree well with the results obtained by a RANS method.

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