Measurements of a Wall Jet Impinging Onto a Forward Facing Step

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
D. C. Langer ◽  
B. A. Fleck ◽  
D. J. Wilson
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Cfd Simulation ◽  
Velocity Ratio ◽  
Water Channel ◽  
Cross Flow ◽  
Elliptical Cross Section ◽  
Navier Stokes ◽  
Wall Jet ◽  
Elliptical Cross

This study examines a horizontal wall jet impinging onto a forward facing vertical step in a cross-flow. Planar laser induced fluorescence (PLIF) experiments in a 68×40 mm2 water channel indicate how the wall-jet flow after impinging onto the step becomes a vertical jet with an elliptical cross section. This study proposes predictive empirical correlations for the aspect ratio and perimeter of the jet’s elliptical cross section based on the step geometry and the inlet flow conditions. A numerical model is also presented, which was produced from a commercial Reynolds averaged Navier–Stokes computational fluid dynamics (CFD) code with the k-ϵ closure model. The experimental results were well represented by correlations for the perimeter P and aspect ratio S using the parameters H (the step height), L∘ (the distance from the jet represented as a point source to the step), and R (the velocity ratio). The CFD simulation was able to predict the trends in the perimeter (under different conditions), aspect ratio, and the shape of the concentration profile, but overpredicted the jet’s perimeter by approximately 50%. The results of these tests are required as input parameters when modeling jet trajectories.

Jet Interaction in Cross Flow: Experimental and Numerical Model

2014 ◽  
Author(s):  
Celso Almeida ◽  
António A. Nunes ◽  
Senhorinha Teixeira ◽  
José Carlos Teixeira ◽  
Pedro Lobarinhas
Keyword(s):  
Wind Tunnel ◽  
Cross Section ◽  
Large Scale ◽  
Cfd Simulation ◽  
Free Stream ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Stream Velocity ◽  
Entire Cross Section ◽  
Injection Point

Ventilation of wide spaces often requires a correct mixing of a jet in a cross flow. The present paper describes the application of Computational Fluid Dynamics (CFD) to model the interaction of a free stream jet with a cross flow, taking into account temperature gradients between the two streams. The model uses the finite volume technique for solving the conservation equations of fluid: mass, momentum and energy. Buoyancy is described by the Boussinesq approximation. The convergence of the solution required a high mesh refinement in the region of flow interaction. The data were compared with experimental results obtained in a subsonic wind tunnel. The experiments were carried out along the 4.0 m long test section of a 1.4×0.8 low speed wind tunnel. The jets were injected at 90° through orifices 25 mm in diameter drawn from a plenum either at the same or higher temperature the free stream. The jet velocity to the free stream velocity ratio was set at 8 for a single jet and between 4 and 16 for multiple injections. Data include velocity, pressure and temperature. The results show that the injection of relatively small cross-flow rates can cause the development of large regions of interaction with the main flux, accompanied by the creation of large scale flow structures, which contribute effectively to rapid mixing of the two streams. A CFD simulation of temperature showed that a jet 30 diameters downstream (30D) is an extension of the plume covering almost half of the cross section and a good homogeneity, then the extension of the plume 120D which covers almost the entire cross section and an optimum mixing occurs. The CFD simulation temperature of 13 jets showed that a toroidal extension of the plume and a good homogenization as early as 30D downstream of the injection point, occurs.

Theoretical Analysis on the Secondary Flow in a Rotating Helical Pipe With an Elliptical Cross Section

2005 ◽  
Vol 128 (2) ◽  
pp. 258-265 ◽  
Author(s):  
Yitung Chen ◽  
Huajun Chen ◽  
Jinsuo Zhang ◽  
Hsuan-Tsung Hsieh
Keyword(s):  
Secondary Flow ◽  
Cross Section ◽  
Centrifugal Force ◽  
Stokes Equations ◽  
Elliptical Cross Section ◽  
Navier Stokes ◽  
Incline Angle ◽  
Elliptical Cross ◽  
Helical Pipe ◽  
Flow Intensity

In the present study, the flow in a rotating helical pipe with an elliptical cross section is considered. The axes of the elliptical cross section are in arbitrary directions. Using the perturbation method, the Navier-Stokes equations in a rotating helical coordinate system are solved. The combined effects of rotation, torsion, and geometry on the characteristics of secondary flow and fluid particle trajectory are discussed. Some new and interesting conclusions are obtained, such as how the number of secondary flow cells and the secondary flow intensity depends on the ratio of the Coroilis force to the centrifugal force. The results show that the increase of torsion has the tendency to transfer the structure of secondary flow into a saddle flow, and that the incline angle α increases or decreases the secondary flow intensity depending on the resultant force between the Corilois force and centrifugal force.

Design Formulae for Elliptical Cross-Section Helical Springs

1992 ◽  
Vol 114 (4) ◽  
pp. 667-669 ◽  
Author(s):  
Kosuke Nagaya ◽  
Yasuo Hirata ◽  
Toyoaki Tsurumi ◽  
Sadahiko Takeda ◽  
Ken-ichi Nagai ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Aspect Ratio ◽  
Cross Section ◽  
Maximum Stress ◽  
The Other ◽  
Elliptical Cross Section ◽  
Elliptical Cross ◽  
Design Formula ◽  
Helical Springs ◽  
Present Design

The maximum stress in elliptical cross-section coil springs with a certain aspect ratio becomes small as compared to the other springs used in practical machines. This article presents a simplified stress expression for designing elliptical cross-section coil springs. The stresses obtained by the present design formula are compared with those by calculated using numerical methods. It is ascertained that the present formula is applicable to design the elliptical cross-section coil springs.

Two-Phase Flow (Oil and Water) in Ducts with the Elliptical Cross-Section: Modeling and Simulation

2019 ◽  
Vol 24 ◽  
pp. 61-75
Author(s):  
J.L. de Oliveira ◽  
A.G. Barbosa de Lima ◽  
R. Pereira Ramos ◽  
H. Luma Fernandes Magalhães ◽  
W.R. Gomes dos Santos ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Cross Section ◽  
Operating Cost ◽  
Circular Cross Section ◽  
Elliptical Cross Section ◽  
Two Phase ◽  
Elliptical Cross ◽  
Ansys Cfx ◽  
Velocity Pressure

In the oil industry, pipelines (circular ducts) are widely used for the transportation of oil and yours derived. Because of their advantages, such as low operating cost and increased safety during transportation, pipelines have become indispensable for transporting oil in large quantities and for long distances. As an alternative to this problem, the transport of oil and water can be accomplished using ducts with an elliptical cross-section. Thus, this work has the objective of studying the flow of oil and water in cylindrical ducts with an elliptical cross-section by using the Ansys CFX software. Results of the velocity, pressure and volumetric fraction distributions of the oil and water phases are presented and analyzed. By applying the same inlet velocity to oil and water, revealed that the elliptical duct, with aspect ratio equal to 5.0, has a pressure drop less (84.2%) than the pressure drop obtained for one duct of circular cross-section (aspect ratio equal to 1.0).

scholarly journals Semi analytical method for calculating Dean's vortex in Torus of elliptical cross section

2019 ◽  
Vol 286 ◽  
pp. 07004
Author(s):  
S. Ajgoun ◽  
J. Khalid Naciri ◽  
R. Khatyr
Keyword(s):  
Cross Section ◽  
Analytical Method ◽  
Stokes Equations ◽  
Fluid Motion ◽  
Stationary Flow ◽  
Elliptical Cross Section ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Elliptical Cross ◽  
Curved Pipe

Based on the work of Dean (1927 and 1928) [1-2] and Cuming (1952) [3], the stationary flow of an incompressible Newtonian fluid through a curved pipe of uniform curvature and with elliptic cross section is studied. The Navier-Stokes equations are expressed in toroïdal coordinates system (s,r,θ). Following Dean’s approach, the governing equations for the fluid motion through a curved elliptical channel are solved by using an original semi analytical method for the resolution of a biharmonic equation. The main interest in this study is to test and validate in the case of an elliptical cross section the proposed semi-analytical method. The latter can then be used for other geometries for which explicit solutions are not available.

Magnetization and AC loss in a superconductor with an elliptical cross-section and arbitrary aspect ratio

2002 ◽  
Vol 377 (1-2) ◽  
pp. 156-164 ◽  
Author(s):  
Bennie ten Haken ◽  
Jan-Jaap Rabbers ◽  
Herman H.J. ten Kate
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Ac Loss ◽  
Elliptical Cross Section ◽  
Elliptical Cross

The Case for the Elliptical Spine

2003 ◽  
Vol 125 (2) ◽  
pp. 217-220
Author(s):  
Gerald L. McIntyre ◽  
Allan D. Kraus
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Circular Cross Section ◽  
Elliptical Cross Section ◽  
Input Admittance ◽  
Elliptical Cross ◽  
Fin Efficiency ◽  
Temperature Excess

The spine (fin) efficiency is abandoned and the input admittance, defined as the ratio of the heat dissipated by the spine to the temperature excess at the spine base, is established as the parameter for comparison of the performance of the spines of circular, square and elliptical cross section. It is shown that the square cross section outperforms the circular cross section and by adjusting the aspect ratio of the elliptical spine, the spine can meet and eventually surpass the performance of the square spine.

Saint–Venant torsion of anisotropic elliptical bar

2017 ◽  
Vol 45 (3) ◽  
pp. 286-294 ◽  
Author(s):  
István Ecsedi ◽  
Attila Baksa
Keyword(s):  
General Solution ◽  
Cross Section ◽  
Elliptical Cross Section ◽  
Elliptical Cross

The object of this article is the Saint–Venant torsion of anisotropic, homogeneous bar with solid elliptical cross section. A general solution of the Saint–Venant torsion for anisotropic elliptical cross section is presented and some known results are reformulated. The case of non-warping cross section is analysed.

scholarly journals The Tidal Potential of a Homogeneous Torus with an Elliptical Section of the Sleeve

2016 ◽  
Vol 25 (3) ◽  
Author(s):  
B. P. Kondratyev ◽  
N. G. Trubitsyna
Keyword(s):  
Cross Section ◽  
Kuiper Belt ◽  
Analytical Form ◽  
Elliptical Cross Section ◽  
External Region ◽  
Elliptical Cross ◽  
Tidal Potential ◽  
Gravitational Model ◽  
Elliptical Section

AbstractIn this paper the problem of the tidal potential of a homogeneous gravitating torus with an elliptical cross-section sleeve is solved. In particular, the potentials in analytical form in the vicinity of the center of the torus and its external region are found. This torus can serve as a gravitational model of the Kuiper belt.

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