Author: A. Brosh
Publisher:
ISBN:
Category :
Languages : en
Pages : 46

Get Book Here

Book Description

Author: Manouchehr Heidarpour
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
This study examines the effects of suction (i.e. lateral flow through the walls) on the structure of a fully developed turbulent pipe flow. Also the effect of suction on pressure gradient and pressure change is examined experimentally. The frictional characteristics of Irrigro$\sp{\circler,}$ the porous tubing used in this investigation, is studied by means of a comprehensive experimental program that considered different lengths of porous tubing. Three aspects of flow in porous pipes are investigated in this study, (i) a computational study of the effects of suction on the flow characteristics, (ii) an experimental study of the frictional characteristics of the porous tubing with no suction condition and (iii) an experimental study of pressure change along a porous tubing with lateral flow. The numerical study of turbulent pipe flow with wall suction rates ranging from A = 0 to 13 percent showed that in fully developed pipe flow, wall suction results in a more uniform velocity distribution with increased near-wall velocity values and reduced velocities near the centerline. The near-wall component of radial velocity, $\nu,$ increases with increasing distance from the wall in the zone near the pipe wall. The absolute levels of turbulent kinetic energy decrease with increasing suction rate. Wall suction increases the wall shear stress, $\tau\sb{\rm w},$ along the wall of the tube. The increase in $\tau\sb{\rm w}$ is significant even for the smallest suction rate (up to 30 percent) while such an increase is much higher for A = 13 percent (up to 360 percent). Analysis of the experimental friction loss data obtained for small diameter porous tubing in this study confirmed that the Colebrook and White (C-W) equation is a very accurate predictor of the friction factor for porous tubing with small diameter size and Reynolds numbers less than 100,000. These results are in agreement with the results of Aggarwal et al (1972). The value of the relative roughness obtained in this study showed that the porous tubing under study is smoother than most of the tubing used as laterals in the traditional trickle irrigation. Also, the fact that the friction factors agreed with the Colebrook-White law indicates that the physical roughness in the porous tubing under study corresponds very nearly to the equivalent sand roughness with a relative roughness of about e/D = 0.002. A relationship was established as a convenient and accurate head loss prediction equation (within 5% error) by combining a power function with the Darcy-Weisbach equation. The combination equation is correctable for viscosity changes and accurate for the porous pipe tubing under study. A pressure change and a pressure gradient prediction relationship were established in the transition zone of the Moody diagram for high suction rates, assuming a uniform radial flow rate along the suction region. The relationships presented herein are based on a control volume approach analysis and incorporated the data obtained from laboratory studies on the porous tubing under study.

Author: Harold L. Weissberg
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 250

Get Book Here

Book Description

Author: Reuben M. Olson
Publisher:
ISBN:
Category : Speed
Languages : en
Pages : 11

Get Book Here

Book Description

Author: Donald Hiroshi Tanaka
Publisher:
ISBN:
Category : Navier-Stokes equations
Languages : en
Pages : 72

Get Book Here

Book Description
The study of flow induced phenomena at the interface between a solid body and a fluid in contact with it is essential to the understanding of such vital engineering problems as drag, flow noise and other energy dissipation characteristics of turbulent flow. At present, investigations have been made of flow properties near a solid boundary and the results extrapolated to the boundary itself by means of energy and momentum conservation principles. The results of these experiments tend to support the theory; however, the data is sparse and many assumptions and secondary mathematical relations must be used before this can be achieved. In this study shear stress was measured at the wall itself using flush-mounted hot-film anemometers. The purpose was to test two models of the structure of the viscous sublayer. The test apparatus consisted of a pipe four inches in diameter and forty feet long connected to a water reservoir in a closed loop design. The test section was located near the end of the pipe to assure fully developed flow conditions. Fluctuating wall shear stress was measured to determine a model of the viscous sublayer.

Author: Jiann-Lih Hwang
Publisher:
ISBN:
Category :
Languages : en
Pages : 480

Get Book Here

Book Description

Author: Reuben M. Olson
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 234

Get Book Here

Book Description

Author: James T. Price
Publisher:
ISBN:
Category : Turbulence
Languages : en
Pages : 78

Get Book Here

Book Description

Author: N. Rajaratnam
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description

Author: R. W. Allen
Publisher:
ISBN:
Category :
Languages : en
Pages : 59

Get Book Here

Book Description
The report deals with the flow-friction induced by wall suction at the boundary walls of main channels in missile transpiration-cooling systems, gas-turbine heat exchangers, porous-wall chemical reactors, and pipe condensers of space power plants. The pronounced effect of wall suction on the friction of turbulent flow in these systems prompts a search for verified engineering flow-friction correlations. Results of a series of experiments are reported, together with an analysis of related experiments reported earlier in the literature. Comparisons are made with previous porous-pipe turbulent-flow experiments of Weissberg and Berman and with the later porous-pipe experiments of Burnage and the results of the self-similar analytical theory of turbulent pipe-flow with suction are also compared with experiment. (Author Modified Abstract).