Turbulent Flow of Water in Plane Curved Channels of Finite Depth

1963 ◽  
Vol 85 (3) ◽  
pp. 377-390 ◽  
Author(s):  
O. G. Brown ◽  
A. W. Marris
Keyword(s):  
Experimental Study ◽  
Shear Flow ◽  
Turbulent Flow ◽  
Finite Depth ◽  
Width Ratio ◽  
Mean Flow ◽  
Curved Channel ◽  
Flow Acceleration ◽  
Curved Channels ◽  
Convex Wall

An experimental study of turbulent flow in a plane curved channel of depth-to-width ratio 8:1 and mean radius-to-width ratio 1.83:1 by means of measured distributions of mean peripheral velocity and pressure and flow visualization methods using dye. It appears that due to the large depth-to-width ratio, the secondary flow, though appreciable, is apparent mainly in the end plate regions. Even so it has a pronounced effect on the flow near the inner (convex) wall. It appears that the sharp curvature is effective in quenching the turbulence of the entering rectilinear shear flow at the inner wall of the curved channel by causing a mean flow acceleration in this region. The study indicates that localized backflows can occur at the inner wall at the meeting of secondary and main flows under near-laminar conditions.

STEADY STATE HEAT TRANSFER TO FULLY DEVELOPED TURBULENT FLOW IN A CURVED CHANNEL

1957 ◽  
Vol 35 (4) ◽  
pp. 410-434
Author(s):  
A. W. Marris
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Mean Flow ◽  
Curved Channel ◽  
Mean Velocity ◽  
Fully Developed Turbulent Flow ◽  
Angular Velocities ◽  
The Mean

A vorticity transfer analogy theory of turbulent heat transfer is developed first for the case of fully developed turbulent flow under zero transverse pressure and temperature gradients such as that in the annulus between concentric cylinders rotating with different angular velocities or in a "free vortex". The mean flow is assumed to be two-dimensional. The theory, which requires that the turbulence be statistically isotropic, yields a temperature distribution in agreement with experiment except in narrow regions immediately adjacent to the boundaries. An argument is given to show that the boundary layer thickness should be of the order of the reciprocal of the square root of the mean velocity, these boundaries are introduced, and Nusselt moduli are defined and their dependence on Reynolds and Prandtl numbers is investigated.The temperature distributions for the case of non-zero transverse temperature and pressure gradients, i.e. for the case of flow in a curved channel in which the fluid does not flow back into itself, are then obtained and the applicability of the simpler equations for zero transverse gradients to this case is investigated.

scholarly journals Experimental study and performance comparison on various types of rectangular piano key side weirs at a 120° section of a 180° curved channel

2020 ◽  
Vol 10 (10) ◽  
Author(s):  
Yaser Mehri ◽  
Solmaz Esmaeili ◽  
Jaber Soltani
Keyword(s):  
Experimental Study ◽  
Discharge Coefficient ◽  
Performance Comparison ◽  
Effective Length ◽  
Bend Angle ◽  
Curved Channel ◽  
Curved Channels ◽  
Water Conveyance ◽  
And Performance ◽  
Side Weirs

Abstract Application of side weirs with high effective length is necessary to discharge excessive flows, to control the flow in water conveyance systems, and irrigation and drainage systems. Most of the studies on the side weirs have been conducted on the straight channels and linear weirs. The flow pattern on the outer arc of the curved channels and its suitability for side weir can be used and combined with the piano key weirs. So far, no comparison has been made on rectangular piano key side weirs (RPKSW) at a 120° Section of a 180° Curved Channel. In this study, an experimental study was performed on A-, B-, C-, and D-type RPKSW at a bend angle of 120 degrees. The results showed that the specific energy at two ends of the RPKSWs was the same, with a slight difference of 3.4% for A-Type, 1.3% for B-Type, 1.1% for C-Type, and 1.8% for D-Type weirs. The discharge coefficients of the studied weirs were also investigated, and it was concluded that B-Type weir has better performance than other weirs. On average, the discharge coefficient of B-Type weir was 9.9%, 21.2%, and 24.1% higher than that of A-Type, C-Type, and D-Type weir, respectively. It was shown that the ratio of P/h1 is the main parameter affecting the weir discharge coefficient. Finally, an empirical equation was proposed for each weir. The proposed equation has MAE = 0.028 for A-Type weir, MAE = 0.041 for B-Type weir, MAE = 0.049 for C-Type weir, and MAE = 0.053 for D-Type weir.

Relaxation of Spatially Advancing Coherent Structures in a Turbulent Curved Channel Flow

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Koji Matsubara ◽  
Tomoya Ohishi ◽  
Keisuke Shida ◽  
Takahiro Miura
Keyword(s):  
Small Scale ◽  
Computational Domain ◽  
Mean Flow ◽  
Curved Channel ◽  
Concave Wall ◽  
Convex Wall ◽  
Mean Pressure ◽  
Coherent Vortex ◽  
The Mean ◽  
Scale Turbulence

A direct numerical simulation is made for the incompressible turbulent flow in the 180 deg curved channel with a long straight portion connected to its exit port. An examination is made for how the organized coherent vortex grows and decays in the curved channel: the radius ratio of 0.92, the aspect ratio of 7.2, and the succeeding straight section length of 75 times the channel half width. The 1552 × 91 × 128 ( = 18,427,136) grids are allocated to the computational domain. The frictional-velocity-based Reynolds number is kept at 150 to resolve the long domain including curved and straight regions. In contrast to that the coherent vortex grows along the concave wall, the vortex remains strong in the convex-wall side after the curvature accompanying a tail of the small-scale turbulence near the convex wall. The dissimilarity between the onset and disappearing of the coherent vortex essentially comes from the mean pressure gradient, which aids or averts the near-wall fluid oppositely between the curvature inlet and the exit. The mean flow is decelerated near the inlet of the convex wall to destabilize the flow and to trigger the onset of the coherent vortex. Contrary, the mean flow is accelerated near the exit of the convex wall to weaken the coherent vortex, and is decelerated near the exit of the concave wall to enhance the turbulence. Therefore, the turbulence enhancement and attenuation occurs oppositely between the inlet and exit of the curvature, and the coherent vortex draws a wake in the convex-side rather than the concave-side where it starts.

Radial Distributions of Temporal-Mean Peripheral Velocity and Pressure for Fully Developed Turbulent Flow in Curved Channels

1960 ◽  
Vol 82 (3) ◽  
pp. 528-536 ◽  
Author(s):  
A. W. Marris
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Rectangular Cross Section ◽  
Width Ratio ◽  
Curved Channels ◽  
Peripheral Velocity ◽  
Wide Range ◽  
Fully Developed Turbulent Flow ◽  
The Mean ◽  
Moving Fluid

Experimental results are presented for the radial distributions of pressure and peripheral velocity for the turbulent flow of water in two closed curved channels of rectangular cross section and large depth-to-width ratio. The traverses were taken at the equatorial section of the channel and sufficiently far around the curve for the effect of curvature on the mean motion to be fully established. The two channels employed had widely differing mean-radius-to-width ratios n. The data obtained for a wide range of flow rates in the channel with a larger n indicated that Reynolds similarity existed between the flows in this channel. These data are compared with the pressure and velocity profiles predicted by potential flow theory and with a semiempirical logarithmic velocity distribution. Results obtained for the channel with smaller n showed that at above a certain Reynolds number an anomaly occurred in the flow, manifesting itself as an unstable “belt” of faster moving fluid, which moved outward from the inner wall as the Reynolds number was increased. This effect, considered to be the consequence of upstream stall, was accompanied by an adverse longitudinal-pressure gradient at the inner wall of the channel. It appeared to be eliminated by the insertion of an upstream splitter vane.

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