Numerical Simulation and Experimental Verification of a Vertical Jet in Swirling Cross-Flow

2012 ◽  
Vol 235 ◽  
pp. 90-95
Author(s):  
Shun Li Kou ◽  
Guo Neng Li
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Flow Velocity ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Tunable Laser ◽  
Simulation Method ◽  
Numerical Results ◽  
Cross Flow Velocity ◽  
Vertical Jet

In order to investigate the bending and mixing characteristics in a vertical jet issuing into a swirling cross-flow, large eddy simulation method was employed to simulate the flow field of a jet in swirling cross-flow. Several jet to cross-flow velocity ratios (r=15, 30, 60) were investigated. The numerical results were compared to the experimental data measured from a phase tunable laser and CCD system. The Reynolds number Re based on the characteristic length of the cross-flow tunnel and the jet velocity lies between 22,537 and 90,146. Numerical results showed that the penetration depth of the vertical jet maintains nearly unchanged when the jet to cross-flow velocity ratio is large enough (r>30), which agreed well with the experimental data and was different from the flow field of jet in straight cross-flow. On the other hand, the case of r=60 obtained largest spread width, and the spread width maintains relatively large in a large penetration zone, which is consist with the experimental finding.

Theoretical Analysis of CO2 Bubble Formation in Anode Flow Field of μDMFC

2014 ◽  
Vol 635-637 ◽  
pp. 346-353 ◽  
Author(s):  
Miao Miao Li ◽  
Jun Geng ◽  
Ru Peng Zhu
Keyword(s):  
Mathematical Model ◽  
Theoretical Analysis ◽  
Flow Field ◽  
Flow Velocity ◽  
Liquid Velocity ◽  
Bubble Formation ◽  
Cross Flow ◽  
Carbon Paper ◽  
Gas Velocity ◽  
Cross Flow Velocity

A mathematical model was established and validated to predict the microbubble diameter when it departing from the carbon paper and moving into the channel of μDMFC. Single bubble behaviors were studied using the model, which took the gas velocity, liquid cross-flow velocity, micro porous diameter and other parameters into account. Results indicate that the microbubble departure diameter decreases with the increasing liquid velocity, and increases with the increasing micro porous diameter and increasing gas velocity.

Cross Flows in Bounded Three-Dimensional Turbulent Boundary Layers

1973 ◽  
Vol 15 (4) ◽  
pp. 274-284 ◽  
Author(s):  
J. H. Horlock
Keyword(s):  
Experimental Data ◽  
Flow Velocity ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Cross Flow ◽  
Turbulent Boundary Layers ◽  
Cross Flow Velocity ◽  
Flow Through ◽  
Bounding Surfaces ◽  
Analytical Expressions

A study is made of the flow normal to the mainstream direction (cross flow) that takes place in three-dimensional ‘bounded’ turbulent boundary layers near a wall, i.e. boundary layers restricted by the presence of bounding surfaces normal to that wall. Such boundary layers are present in the flow through rows of blades in a turbo machine. Analytical expressions for the cross-flow velocity profiles are derived for these ‘bounded’ boundary layers and are compared with experimental data.

Effects of alternating elliptical chamber on jet impingement heat transfer in vane leading edge under different cross-flow conditions

2021 ◽  
pp. 1-17
Author(s):  
K. Xiao ◽  
J. He ◽  
Z. Feng
Keyword(s):  
Heat Transfer ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Leading Edge ◽  
Longitudinal Vortices ◽  
Impingement Jet ◽  
Flow And Heat Transfer ◽  
Impingement Heat Transfer ◽  
Cross Flow Velocity ◽  
The Cross

ABSTRACT This paper proposes an alternating elliptical impingement chamber in the leading edge of a gas turbine to restrain the cross flow and enhance the heat transfer, and investigates the detailed flow and heat transfer characteristics. The chamber consists of straight sections and transition sections. Numerical simulations are performed by solving the three-dimensional (3D) steady Reynolds-Averaged Navier–Stokes (RANS) equations with the Shear Stress Transport (SST) k– $\omega$ turbulence model. The influences of alternating the cross section on the impingement flow and heat transfer of the chamber are studied by comparison with a smooth semi-elliptical impingement chamber at a cross-flow Velocity Ratio (VR) of 0.2 and Temperature Ratio (TR) of 1.00 in the primary study. Then, the effects of the cross-flow VR and TR are further investigated. The results reveal that, in the semi-elliptical impingement chamber, the impingement jet is deflected by the cross flow and the heat transfer performance is degraded. However, in the alternating elliptical chamber, the cross flow is transformed to a pair of longitudinal vortices, and the flow direction at the centre of the cross section is parallel to the impingement jet, thus improving the jet penetration ability and enhancing the impingement heat transfer. In addition, the heat transfer in the semi-elliptical chamber degrades rapidly away from the stagnation region, while the longitudinal vortices enhance the heat transfer further, making the heat transfer coefficient distribution more uniform. The Nusselt number decreases with increase of VR and TR for both the semi-elliptical chamber and the alternating elliptical chamber. The alternating elliptical chamber enhances the heat transfer and moves the stagnation point up for all VR and TR, and the heat transfer enhancement is more obvious at high cross-flow velocity ratio.

Significance of Lorentz Force and Thermoelectric on the Flow of 29 nm CuO–Water Nanofluid on an Upper Horizontal Surface of a Paraboloid of Revolution

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
I. L. Animasaun ◽  
B. Mahanthesh ◽  
A. O. Jagun ◽  
T. D. Bankole ◽  
R. Sivaraj ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Cross Flow ◽  
Horizontal Surface ◽  
Integration Scheme ◽  
Flowing Fluid ◽  
Paraboloid Of Revolution ◽  
Hall Parameter ◽  
Cross Flow Velocity

Combination of electric and magnetic forces on charged molecules of flowing fluid in the presence of a significant electromagnetic fields on surfaces with a nonuniform thickness (as in the case of upper pointed surface of an aircraft and bonnet of a car which are examples of upper horizontal surfaces of a paraboloid of revolution—uhspr) is inevitable. In this study, the influence of imposed magnetic field and Hall effects on the flow of 29 nm CuO–water nanofluid over such object is presented. Suitable similarity variables were employed to nondimensionalize and parameterize the dimensional governing equation. The numerical solutions of the corresponding boundary value problem were obtained using Runge–Kutta fourth-order integration scheme along with shooting technique. The domain of cross-flow velocity can be highly suppressed when the magnitude of imposed magnetic strength and that of Hall parameter are large. A significant increase in the cross-flow velocity gradient near an upper horizontal surface of the paraboloid of revolution is guaranteed with an increase in the Hall parameter. Enhancement of temperature distribution across the flow is apparent due to an increase in the volume fraction.

scholarly journals Biofouling Mitigation Approaches during Water Recovery from Fermented Broth via Forward Osmosis

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 307
Author(s):  
Stavros Kalafatakis ◽  
Agata Zarebska ◽  
Lene Lange ◽  
Claus Hélix-Nielsen ◽  
Ioannis V. Skiadas ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Feed Solution ◽  
Mitigation Strategies ◽  
Water Recovery ◽  
Operational Parameters ◽  
Solution Ph ◽  
Sustainable Solutions ◽  
Cross Flow Velocity

Forward Osmosis (FO) is a promising technology that can offer sustainable solutions in the biorefinery wastewater and desalination fields, via low energy water recovery. However, microbial biomass and organic matter accumulation on membrane surfaces can hinder the water recovery and potentially lead to total membrane blockage. Biofouling development is a rather complex process and can be affected by several factors such as nutrient availability, chemical composition of the solutions, and hydrodynamic conditions. Therefore, operational parameters like cross-flow velocity and pH of the filtration solution have been proposed as effective biofouling mitigation strategies. Nevertheless, most of the studies have been conducted with the use of rather simple solutions. As a result, biofouling mitigation practices based on such studies might not be as effective when applying complex industrial mixtures. In the present study, the effect of cross-flow velocity, pH, and cell concentration of the feed solution was investigated, with the use of complex solutions during FO separation. Specifically, fermentation effluent and crude glycerol were used as a feed and draw solution, respectively, with the purpose of recirculating water by using FO alone. The effect of the abovementioned parameters on (i) ATP accumulation, (ii) organic foulant deposition, (iii) total water recovery, (iv) reverse glycerol flux, and (v) process butanol rejection has been studied. The main findings of the present study suggest that significant reduction of biofouling can be achieved as a combined effect of high-cross flow velocity and low feed solution pH. Furthermore, cell removal from the feed solution prior filtration may further assist the reduction of membrane blockage. These results may shed light on the challenging, but promising field of FO process dealing with complex industrial solutions.

A Family of Hodograph Models for the Cross Flow Velocity Component of Three-Dimensional Turbulent Boundary Layers

1972 ◽  
Vol 94 (2) ◽  
pp. 321-329 ◽  
Author(s):  
J. R. Shanebrook ◽  
D. E. Hatch
Keyword(s):  
Flow Velocity ◽  
Boundary Layers ◽  
Velocity Component ◽  
Three Dimensional ◽  
Cross Flow ◽  
Turbulent Boundary Layers ◽  
Flow Profiles ◽  
Rectangular Channels ◽  
Cross Flow Velocity ◽  
The Cross

A family of hodograph models for the cross flow velocity component of three-dimensional, turbulent boundary layers is presented. The principal advantage of this family is its flexibility which allows a wide variety of possible shapes for the hodograph. An integral method based on this family is developed and applied to data obtained in curved, rectangular channels. For the cases treated, the method gives acceptable results for cross flow profiles with and without flow reversal. Suggestions for refining the method are given.

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