scholarly journals Supercritical flow at an abrupt drop: flow patterns and aeration

1998 ◽  
Vol 25 (5) ◽  
pp. 956-966 ◽  
Author(s):  
H Chanson ◽  
L Toombes
Keyword(s):  
Shock Waves ◽  
Open Channel ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Three Dimensional Flow ◽  
Supercritical Flow ◽  
Drop Flow ◽  
Supercritical Flows ◽  
The Impact

Stepped waterways and cascades are common features of storm waterways, at dam outlets, and in water treatment plants. At an abrupt drop, open channel flows are characterized by the presence of shock waves and a substantial flow aeration. There is, however, little information on the basic flow characteristics. The study presents new experimental data obtained in a 0.5-m-wide stepped flume with an unventilated nappe. The investigations describe the three-dimensional flow patterns, including shock waves, standing waves, and spray, downstream of the nappe impact. The characteristics of the flow patterns are similar to those observed with abrupt expansion supercritical flows. Downstream of the drop brink, substantial aeration takes place along the nappe interfaces and the flow downstream of the impact is deaerated.Key words: abrupt drop, supercritical flow, shock waves, flow patterns, cascade.

scholarly journals Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin
Keyword(s):  
Turbulent Flow ◽  
Open Channel ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Recirculation ◽  
Tandem Cylinders ◽  
Flow Development ◽  
The Mean ◽  
Recirculation Length

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.

Numerical Investigation of Positive Displacement Rotary Lobe Pump With Twisted Rotors

2014 ◽  
Author(s):  
Xiaojun Jiang ◽  
Yi Li ◽  
Zhaohui He ◽  
Cui Baoling ◽  
Wenlong Dong
Keyword(s):  
Flow Structure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Dynamic Flow ◽  
Flow Fluctuation ◽  
Flow Field Characteristics ◽  
Lobe Pump ◽  
The Impact

The three-dimensional flow field characteristics are obtained by performing numerical simulation of flow in a lobe pump with twisted rotors. The relationship between the dynamic flow structure and the flow fluctuation is explored. Actually, the viscous incompressible Navier-Stokes equations are solved within an unsteady flow model. The dynamic mesh technique is applied to obtain the dynamic flow structure. By comparing the simulated results of straight rotor with those of twisted rotor, the effect of rotor shape on the flow fluctuation was revealed. Finally, the impact of the lobes number of rotors on flow pulsations is discussed. The results show that there is an intrinsic relationship between the flow fluctuation and the vortex in the lobe pump. The use of twisted rotors can effectively improve the internal flow characteristics of lobe pump and reduce flow fluctuation. With the increase of the number of lobes, the lobe pump output is more stable and capacity has been improved.

Three-dimensional flow patterns in cracking furnaces with long-flame burners

AIChE Journal ◽  
2001 ◽  
Vol 47 (2) ◽  
pp. 388-400 ◽  
Author(s):  
Geraldine J. Heynderickx ◽  
Arno J. M. Oprins ◽  
Guy B. Marin ◽  
Erik Dick
Keyword(s):  
Three Dimensional ◽  
Flow Patterns ◽  
Three Dimensional Flow ◽  
Dimensional Flow

Three-dimensional flow structure at fixed 70° open-channel confluence with bed discordance

2019 ◽  
Vol 58 (3) ◽  
pp. 434-446 ◽  
Author(s):  
Olga Birjukova Canelas ◽  
Rui M.L. Ferreira ◽  
Sebastián Guillén-Ludeña ◽  
Francisco C. Alegria ◽  
António H. Cardoso
Keyword(s):  
Flow Structure ◽  
Open Channel ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Channel Confluence

Prediction of Particle Impact on an Archimedes Screw Runner Blade for Micro Hydro Turbine

2013 ◽  
Vol 465-466 ◽  
pp. 552-556
Author(s):  
Muhammad Ammar Nik Mutasim ◽  
Nurul Suraya Azahari ◽  
Ahmad Alif Ahmad Adam
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Particle Impact ◽  
Three Dimensional Flow ◽  
Navier Stokes Equation ◽  
Runner Blade ◽  
Computational Fluid Dynamics Cfd ◽  
The Subject ◽  
The Impact

Energy is one of the most important sources in the world especially for developing countries. The subject study is conducted to predict the behaviour of particle due to errosion from the river through the achimedes screw runner and predict the impact of particle toward blade surface. For this reason, computational fluid dynamics (CFD) methods are used. The three-dimensional flow of fluid is numerically analyzed using the Navier-Stokes equation with standard k-ε turbulence model. The reinverse design of archimedes screw blade was refered with the previous researcher. Flow prediction with numerical results such as velocity streamlines, flow pattern and pressure contour for flow of water entering the blade are discussed. This study shows that the prediction of particle impact occurs mostly on the entering surface blade and along the leading edge of the screw runner. Any modification on the design of the screw runner blade can be analyze for further study.

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