Fluid-dynamic loading of pipes conveying fluid with a laminar mean-flow velocity profile

2014 ◽  
Vol 50 ◽  
pp. 171-183 ◽  
Author(s):  
J. Kutin ◽  
I. Bajsić
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Dynamic Loading ◽  
Fluid Dynamic ◽  
Mean Flow ◽  
Flow Velocity Profile ◽  
Pipes Conveying Fluid ◽  
Mean Flow Velocity ◽  
Conveying Fluid

scholarly journals Turbulence Modeling Using Z-F Model and RSM for Flow Analysis in Z-SHAPE Ducts

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Mohammed Karbon ◽  
Ahmad K. Sleiti
Keyword(s):  
Steady State ◽  
Velocity Profile ◽  
Flow Velocity ◽  
Flow Separation ◽  
Experimental Results ◽  
Mean Flow ◽  
Flow Velocity Profile ◽  
The Mean ◽  
Mean Flow Velocity ◽  
Flow Reattachment

Turbulent flow in Z-shape duct configuration is investigated using Reynolds stress model (RSM) and ζ-f model and compared to experimental results. Both RSM and ζ-f models are based on steady-state RANS solutions. The focus was on regions where the RSM has over- or underpredicted the flow when compared to the experimental results and on regions where there are flow separations and high turbulence. The performance of predicting the flow reattachment length in each model is studied as well. RSM has shown the mean flow velocity profile results match reasonably well with the experiment. Advanced ζ-f turbulence model is introduced as user-defined function (UDF) code and applied to the Z-shape duct. It is found that the turbulent kinetic energy production in ζ equation is much easier to reproduce accurately. Both mean velocity gradient and local turbulent stress terms are also much easier to be resolved properly. The current research has found that not only ζ-f model takes less time to complete the simulation but also the mean flow velocity profile results are in better agreement with the experimental data than the RSM although both are coupled steady-state RANS. ζ-f model numerically resolved both the flow separation and reattachment regions better than the RSM. The current numerical results from ζ-f model are attractive and encouraging for wall-bounded flow applications where flow separation and flow reattachment are important for the flow mechanism.

scholarly journals Anterior-to-posterior wave of buccal expansion in suction feeding fishes is critical for optimizing fluid flow velocity profile

2008 ◽  
Vol 5 (28) ◽  
pp. 1309-1316 ◽  
Author(s):  
Kristin L Bishop ◽  
Peter C Wainwright ◽  
Roi Holzman
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Prey Capture ◽  
Peak Flow ◽  
Fluid Dynamic ◽  
Time Lag ◽  
Mouth Opening ◽  
Suction Feeding ◽  
Peak Flow Velocity ◽  
Flow Velocity Profile

In fishes that employ suction feeding, coordinating the timing of peak flow velocity with mouth opening is likely to be an important feature of prey capture success because this will allow the highest forces to be exerted on prey items when the jaws are fully extended and the flow field is at its largest. Although it has long been known that kinematics of buccal expansion in feeding fishes are characterized by an anterior-to-posterior wave of expansion, this pattern has not been incorporated in most previous computational models of suction feeding. As a consequence, these models have failed to correctly predict the timing of peak flow velocity, which according to the currently available empirical data should occur around the time of peak gape. In this study, we use a simple fluid dynamic model to demonstrate that the inclusion of an anterior-to-posterior wave of buccal expansion can correctly reproduce the empirically determined flow velocity profile, although only under very constrained conditions, whereas models that do not allow this wave of expansion inevitably predict peak velocity earlier in the strike, when the gape is less than half of its maximum. The conditions that are required to produce a realistic velocity profile are as follows: (i) a relatively long time lag between mouth opening and expansion of the more posterior parts of the mouth, (ii) a short anterior portion of the mouth relative to more posterior sections, and (iii) a pattern of movement that begins slowly and then rapidly accelerates. Greater maximum velocities were generated in simulations without the anterior-to-posterior wave of expansion, suggesting a trade-off between maximizing fluid speed and coordination of peak fluid speed with peak gape.

Experimental Investigation of Mean Flow Profile Effects on Impedance Eduction

2021 ◽  
Vol 263 (1) ◽  
pp. 5858-5868
Author(s):  
Victor Kopiev ◽  
NIkolay Ostrikov ◽  
Stanislav Denisov ◽  
MIkhail Yakovets ◽  
Maxim Ipatov
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Cross Section ◽  
Three Dimensional ◽  
Descent Method ◽  
Gradient Descent Method ◽  
Flow Profile ◽  
Mean Flow ◽  
Flow Velocity Profile ◽  
Made In

The results of experimental and computational studies of the three-dimensional mean flow velocity profile influence on the impedance eduction are presented. In order to measure the three-dimensional velocity profile, the TsAGIâ€(tm)s “Interferometer with flow†facility was upgraded so that additional holes were made in one cross section of the rectangular duct. As a result, it became possible to measure the longitudinal flow velocity in this cross section along 6 lines using a Pitot tube or a hot wire anemometer. The full three-dimensional velocity profile is determined by interpolating the values measured.Experimental results of the velocity profile for various experiment conditions are presented. Based on the numerical solution of the three-dimensional Pridmore-Brown equation by means of Finite Element Method and the gradient descent method, the problem of impedance eduction are investigated. The influence of the flow velocity profile and the form of functional on the obtained impedance values are discussed. The impedance values educted by means of this approach are compared with the impedance values obtained using two-dimensional impedance eduction methods, which didnâ€(tm)t taking into account the three-dimensional non homogeneity of the flow velocity field.

Investigation of the influence of the flow structure on the accuracy of flow measurement before a hydrometric structure in an open channel

2020 ◽  
pp. 41-44
Author(s):  
Anatoly Kusher
Keyword(s):  
Velocity Profile ◽  
Flow Velocity ◽  
Water Flow ◽  
Flow Measurement ◽  
Water Discharge ◽  
Critical Depth ◽  
Flow Measurements ◽  
Study Results ◽  
Flow Velocity Profile ◽  
Upstream Flow

The reliability of water flow measurement in irrigational canals depends on the measurement method and design features of the flow-measuring structure and the upstream flow velocity profile. The flow velocity profile is a function of the channel geometry and wall roughness. The article presents the study results of the influence of the upstream flow velocity profile on the discharge measurement accuracy. For this, the physical and numerical modeling of two structures was carried out: a critical depth flume and a hydrometric overfall in a rectangular channel. According to the data of numerical simulation of the critical depth flume with a uniform and parabolic (1/7) velocity profile in the upstream channel, the values of water discharge differ very little from the experimental values in the laboratory model with a similar geometry (δ < 2 %). In contrast to the critical depth flume, a change in the velocity profile only due to an increase in the height of the bottom roughness by 3 mm causes a decrease of the overfall discharge coefficient by 4…5 %. According to the results of the numerical and physical modeling, it was found that an increase of backwater by hydrometric structure reduces the influence of the upstream flow velocity profile and increases the reliability of water flow measurements.

Experimental Investigation of the Acoustic Reflection Coefficient of a Modeled Gas Turbine Impingement Cooling Section

2012 ◽  
Author(s):  
Christoph Jörg ◽  
Michael Wagner ◽  
Thomas Sattelmayer
Keyword(s):  
Reflection Coefficient ◽  
Flow Velocity ◽  
Gas Turbines ◽  
Acoustic Energy ◽  
Quality Data ◽  
Mean Flow ◽  
Impingement Cooling ◽  
Acoustic Reflection ◽  
The Mean ◽  
Mean Flow Velocity

The thermoacoustic stability of gas turbines depends on a balance of acoustic energy inside the engine. While the flames produce acoustic energy, other areas like the impingement cooling system contribute to damping. In this paper, we investigate the damping potential of an annular impingement sleeve geometry embedded into a realistic environment. A cold flow test rig was designed to represent real engine conditions in terms of geometry, and flow situation. High quality data was delivered by six piezoelectric dynamic pressure sensors. Experiments were carried out for different mean flow velocities through the cooling holes. The acoustic reflection coefficient of the impingement sleeve was evaluated at a downstream reference location. Further parameters investigated were the number of cooling holes, and the geometry of the chamber surrounding the impingement sleeve. Experimental results show that the determining parameter for the reflection coefficient is the mean flow velocity through the impingement holes. An increase of the mean flow velocity leads to significantly increased damping, and to low values of the reflection coefficient.

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