Effect of fiber length, flow rate, and concentration on velocity profiles of cellulosic fiber suspensions

2013 ◽  
Vol 224 (10) ◽  
pp. 2301-2310 ◽  
Author(s):  
E. J. Tozzi ◽  
D. M. Lavenson ◽  
M. J. McCarthy ◽  
R. L. Powell
Keyword(s):  
Flow Rate ◽  
Fiber Length ◽  
Velocity Profiles ◽  
Fiber Suspensions ◽  
Cellulosic Fiber

scholarly journals STEREOLOGICAL ESTIMATION OF TOTAL FIBER LENGTH IN ANISOTROPIC FIBER SUSPENSIONS

1979 ◽  
Vol 35 (7) ◽  
pp. T280-T282
Author(s):  
Takashi Komori ◽  
Kunio Makishima
Keyword(s):  
Fiber Length ◽  
Fiber Suspensions ◽  
Anisotropic Fiber

Development of Pulse Ultrasonic Doppler Method for Flow Rate Measurements of Power Plant: Characteristics of Sound Pressure Distributions and Evaluation of the Hybrid Ultrasonic Flowmetering System Using TOF and UDM

2006 ◽  
Author(s):  
Hiroshige Kikura ◽  
Yuto Inoue ◽  
Masanori Aritomi ◽  
Michitsugu Mori
Keyword(s):  
Velocity Profile ◽  
Ultrasonic Velocity ◽  
Flow Rate ◽  
Time Of Flight ◽  
Velocity Profiles ◽  
Instantaneous Velocity ◽  
Rate Measurement ◽  
Flow Rate Measurement ◽  
Doppler Method ◽  
Flow Metering

A multi-beam pulse ultrasonic Doppler method has been developed for a new type of flow metering system. This new system is a hybrid of the time-of-flight type ultrasonic flowmeter and the ultrasonic velocity profile type flowmeter, having the advantages of these two types. Our final purpose is to apply the hybrid ultrasonic flow metering system to an accurate flow rate measurement of feed- or recirculation- water in nuclear power plants. The pulse ultrasonic Doppler method (UDM) has the capability to obtain instantaneous velocity profiles along an ultrasonic beam. The principle of the UDM flowmeter, which is one of the ultrasonic velocity profile type flowmeters, is based on the integration of an instantaneous velocity profile over a pipe diameter. The multi-beam system is expected to eliminate installation problems such as those of entry length, and also to follow transient flow rate more precisely by increasing the number of ultrasonic transducers. However, it needs reflectors for receiving ultrasonic Doppler signals. On the other hand, the time-of-flight (TOF) ultrasonic flow metering system does not need any reflector, but it needs profile factors (PFs) which depend on velocity profiles. PF is one of the important experimental coefficients for the accurate flow rate measurement. Therefore PFs must be corrected according to the changes in flow conditions. In the present study, we investigated to what degree the hybrid ultrasonic flow metering system can adjust the profile factors of the time-of-flight ultrasonic flow meters by using the multi-beam pulse ultrasonic Doppler method in metallic wall piping.

Arterial bifurcation flows – effects of flow rate and area ratio

1976 ◽  
Vol 54 (6) ◽  
pp. 795-808 ◽  
Author(s):  
I. A. Feuerstein ◽  
O. A. El Masry ◽  
G. Round
Keyword(s):  
Flow Rate ◽  
Tracer Particle ◽  
Velocity Profiles ◽  
Area Ratio ◽  
Arterial System ◽  
Surface Shear ◽  
Shear Rates ◽  
Bifurcation Surface ◽  
Parent Tube ◽  
Flow Symmetry

Velocity profiles and surface shear rates, for three model symmetrical bifurcations made of glass from dimensions based on the arterial system, were investigated. The models studied had area ratios of 0.75, 1.02, and 1.29, with a common included angle of 75°. Area ratio and parent tube flow rate were the two independent variables evaluated. Measurements were made with a tracer particle technique using cinephotography. Velocity profiles had their highest values on the inside, and lowest values on the outside, of the branch. Flow symmetry existed in the plane perpendicular to the plane of the bifurcation. Surface shear rates remained well above the daughter-tube developed values, between two and six diameters downstream from the carina. Shear rates below the daughter-tube developed value were found on the outside wall between the carina and two daughter-tube diameters downstream. Vortex-like flow was absent in this region for the 0.75 area ratio branch and was found above 900 Reynolds number in the 1.29 area ratio branch. The disturbed flow described by others in this region may not contain vortex-like streamlines for the physiologically important 0.75 area ratio.

Fractal Orifices for Flowmetering

2012 ◽  
Author(s):  
Franck C. G. A. Nicolleau ◽  
Stephen B. M. Beck ◽  
Andrzej F. Nowakowski
Keyword(s):  
Wind Tunnel ◽  
Flow Rate ◽  
Velocity Profiles ◽  
Symmetric Design ◽  
Flow Properties ◽  
Mean Velocity ◽  
Fractal Pattern ◽  
The Mean

In this article we study the return to axi-symmetry for a flow generated after fractal plates in a circular wind tunnel. We consider two sets of plates: one orifice-like and one perforated-like. The mean velocity profiles are presented at different distances from the plate and we study the convergence of a flow rate based on these profiles. The return to axi-symmetry depends on how far was the original plate from an axi-symmetric design. It also depends on the level of iteration of the fractal pattern. In line with results for other flow properties [1, 2] It seems that there is not much to be gained by manufacturing fractal plates with more than three iteration levels.

Influence of Pipe Roughness on the Performance of Ultrasonic Meters for Flow Rate Measurement

2011 ◽  
Author(s):  
Alcir de Faro Orlando ◽  
Ana Luisa Ferreira ◽  
Jose´ Alberto Pinheiro
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Flow Velocity ◽  
Flow Rate ◽  
Velocity Profiles ◽  
Rate Measurement ◽  
Flow Rate Measurement ◽  
Flow Meters ◽  
Field Distortion ◽  
Pipe Roughness

Ultrasonic flow meters have been recently used for flow rate measurement because they are a non-intrusive device and have the capability of making diagnostics of their performance and flow field distortion between two consecutive calibrations. The available completely developed flow velocity profiles in the literature is discussed in this paper and integrated along the meter ultrasonic path to simulate its performance. It was shown that for Reynolds number up to 1,000,000 and relatively roughness values smaller than ε = 0.00012 the flow is in the hydraulically smooth regime. Also, it was shown that the ratio between the area velocity and the average path velocity (kh) decreases close to centerline and increases close to the wall, when roughness increases.

Numerical Optimization of the Inlet Velocity Profile Ingested by the Conical Draft Tube of a Hydraulic Turbine

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Sergio Galván ◽  
Marcelo Reggio ◽  
Francois Guibault
Keyword(s):  
Velocity Profile ◽  
Flow Rate ◽  
Numerical Optimization ◽  
Draft Tube ◽  
Velocity Profiles ◽  
Plant Performance ◽  
Swirl Number ◽  
Inlet Velocity ◽  
Turbine Performance ◽  
Low Head

Past numerical and experimental research has shown that the draft tube inlet velocity is critically important to hydropower plant performance, especially in the case of low-head installations. However, less is known about the influence of flow parameters on turbine performance particularly swirl distribution. Based on the influence of draft tube flow characteristics on the overall performance of a low-head turbine, this research proposes a methodology for optimizing draft tube inlet velocity profiles as a new approach to controlling the flow conditions in order to yield better draft tube and turbine performance. Numerical optimization methods have been used successfully for a variety of design problems. However, addressing the optimization of boundary conditions in hydraulic turbines poses a new challenge. In this paper, three different vortex equations for representing the inlet velocity profile are applied to a cone diffuser, and the behavior of the objective function is analyzed. As well, the influence of the quantitative correlation between the swirling flow at the cone inlet and the analytical blade shape, flow rate, and swirl number using the best inlet velocity profiles is evaluated. We also include a discussion on the development of a flow structure caused by the inlet swirl parameters. Finally, we present an analysis of the influence of flow rate and swirl number on the behavior of the optimization process.

Secondary Flows in Centrifugal Pump Impellers: PIV Measurements and CFD Computations

2009 ◽  
Author(s):  
R. W. Westra ◽  
L. Broersma ◽  
K. van Andel ◽  
N. P. Kruyt
Keyword(s):  
Reynolds Number ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Stokes Equations ◽  
Suction Side ◽  
Velocity Profiles ◽  
Secondary Flows ◽  
Design Flow ◽  
Low Velocity ◽  
Flow Rates

Two-dimensional Particle Image Velocimetry measurements and three-dimensional Computational Fluid Dynamics (CFD) analyses have been performed of the flow field inside the impeller of a low specific-speed centrifugal pump operating with a vaneless diffuser. Flow rates ranging from 80% to 120% of the design flow rate are considered in detail. It is observed from the velocity measurements that secondary flows occur. These flows result in the formation of regions of low velocity near the intersection of blade suction side and shroud. The extent of this jet-wake structure decreases with increasing flow rate. Velocity profiles have also been computed from Reynolds-averaged Navier-Stokes equations with the Spalart-Allmaras turbulence model, using a commercial CFD-code. For the considered flow rates the qualitative agreement between measured and computed velocity profiles is very good. Overall, the average relative difference between these velocity profiles is around 7%. Additional CFD computations have been performed to assess the influence of Reynolds number and shape of the inlet velocity profile on the computed velocity profiles. It is found that the influence of Reynolds number is mild. The shape of the inlet profile only has a weak effect at the shroud.

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