Study on Spacer Grid Span Pressure Loss Under High Reynolds Number Flow Condition

2009 ◽  
Author(s):  
Kazuo Ikeda ◽  
Yasunao Yamaguchi ◽  
Juntaro Shimizu ◽  
Kaoru Okamoto
Keyword(s):  
Reynolds Number ◽  
Flow Condition ◽  
Pressure Loss ◽  
Reynolds Numbers ◽  
Cfd Model ◽  
Spacer Grid ◽  
Reynolds Number Flow ◽  
Rod Bundle ◽  
Number Flow ◽  
High Reynolds

Pressure loss coefficient of spacer grid is used as a key parameter for PWR core thermal hydraulic design. It has been obtained by single-phase hydraulic testing for many years. However, it is necessary to develop design tool for precise estimation of pressure loss of spacer grids as well as hydraulic tests to meet the needs of the worldwide nuclear fuel market. Recently, Computational Fluid Dynamics (CFD) analysis has been applied for estimation of flow field in a fuel rod bundle. In this study, the numerical simulation in a range of bare rod Reynolds numbers of the reactor flow condition is performed to examine the applicability of the CFD model for estimating spacer grid span pressure loss. For verification of the numerical estimation, the span pressure loss of 5×5 rod bundle with spacer grid is measured in Nuclear Development Corporation (NDC) hydraulic test facility up to bare rod Reynolds number as high as 500,000. The simulation shows good agreement with experimental data in the range of Reynolds numbers. The CFD model is also utilized to investigate the pressure loss as a function of distance from last passed spacer grid and to discuss the turbulent flow characteristics in the rod bundle with spacer grid under high Reynolds number flow condition.

Pressure and Vortex Shedding Patterns Around a Low Aspect Ratio Cylinder in a Sheared Flow at Transitional Reynolds Numbers

1981 ◽  
Vol 103 (1) ◽  
pp. 88-95 ◽  
Author(s):  
D. M. Rooney ◽  
R. D. Peltzer
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Reynolds Numbers ◽  
Pressure Measurements ◽  
Reynolds Number Flow ◽  
Sheared Flow ◽  
Number Flow ◽  
High Reynolds ◽  
First Time ◽  
Upstream Flow

Model tests were performed in a wind tunnel to determine vortex shedding patterns induced around a circular cylinder by spanwise shear in transitional Reynolds number flow. In addition, mean and fluctuating pressure measurements were obtained. The introduction of shear in the upstream flow generated two distinct cells of vortex frequencies behind the cylinder in the transcritical regime, thereby documenting for the first time that the re-established high Reynolds number shedding closely parallels patterns already observed in subcritical flow. The two cell pattern did not permit any correlation between shear level and cell length to be found.

Low Reynolds Number Flow Computations of a Sphere With Slip

2005 ◽  
Author(s):  
O. Pulat ◽  
R. N. Parthasarathy
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Reynolds Numbers ◽  
Water Medium ◽  
Reynolds Number Flow ◽  
Drag Forces ◽  
Falling Sphere ◽  
Number Flow ◽  
High Reynolds ◽  
Flow Past A Sphere

A computational fluid dynamics package (FLUENT) was used to simulate the conditions of a falling sphere through a water medium with a zero shear stress condition (full slip) for Reynolds numbers in the range. Comparisons of the results were made with simulations of the flow past a sphere with no slip. Specific differences were observed in the drag coefficient, drag forces, axial velocity, radial velocity, and wake characteristics. A significant reduction in the drag coefficient was observed with the presence of slip on the surface. With a decrease in the Reynolds number the decreases in the wake structure became negligible, however, the differences in drag coefficient became significant. At high Reynolds numbers, the wake was skewed towards the rear of the sphere, under the full slip condition.

On the low-Reynolds-number flow in a helical pipe

1981 ◽  
Vol 108 ◽  
pp. 185-194 ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Reynolds Numbers ◽  
Order Unity ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Helical Pipe ◽  
Number Flow ◽  
High Reynolds ◽  
Curvature And Torsion

A non-orthogonal helical co-ordinate system is introduced to study the effect of curvature and torsion on the flow in a helical pipe. It is found that both curvature and torsion induce non-negligible effects when the Reynolds number is less than about 40. When the Reynolds number is of order unity, torsion induces a secondary flow consisting of one single recirculating cell while curvature causes an increased flow rate. These effects are quite different from the two recirculating cells and decreased flow rate at high Reynolds numbers.

Low Reynolds number flow around and heat transfer from a heated circular cylinder

2010 ◽  
Vol 1 (1-2) ◽  
pp. 15-20 ◽  
Author(s):  
B. Bolló
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Reynolds Number Flow ◽  
Two Dimensional Flow ◽  
Number Flow ◽  
Low Reynolds ◽  
Increasing Temperature

Abstract The two-dimensional flow around a stationary heated circular cylinder at low Reynolds numbers of 50 < Re < 210 is investigated numerically using the FLUENT commercial software package. The dimensionless vortex shedding frequency (St) reduces with increasing temperature at a given Reynolds number. The effective temperature concept was used and St-Re data were successfully transformed to the St-Reeff curve. Comparisons include root-mean-square values of the lift coefficient and Nusselt number. The results agree well with available data in the literature.

Measurement of Velocity Profiles of Laminar to Turbulent Water Flows in a Tube Using Particle Image Velocimetry

2004 ◽  
Author(s):  
Meredith R. Martin
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Glass Tube ◽  
Reynolds Numbers ◽  
Velocity Profiles ◽  
Reynolds Number Flow ◽  
Image Velocimetry ◽  
Dye Visualization ◽  
Number Flow

The transition from laminar to turbulent in-tube flow is studied in this paper. Water flow in a glass tube with an inside diameter of 21.7 mm was investigated by two methods. First, a dye visualization test using a setup similar to the 1883 experiment of Osborne Reynolds was conducted. For the dye visualization, Reynolds numbers ranging from approximately 1000 to 3500 were tested and the transition from laminar to turbulent flow was observed between Reynolds numbers of 2500 and 3500. For the second method, a particle image velocimetry (PIV) system was used to measure the velocity profiles of flow in the same glass tube at Reynolds numbers ranging from approximately 500 to 9000. The resulting velocity profiles were compared to theoretical laminar profiles and empirical turbulent power-law profiles. Good agreement was found between the lower Reynolds number flow and the laminar profile, and between the higher Reynolds number flow and turbulent power-law profile. In between the flow appeared to be in a transition region and deviated some between the two profiles.

scholarly journals The Effect of Surface Roughness of a Body in the High Reynolds-Number Flow

1995 ◽  
Vol 2 (1) ◽  
pp. 23-32
Author(s):  
Tsutomu adachi
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
High Reynolds Number ◽  
The Body ◽  
Reynolds Number Flow ◽  
Flow Phenomena ◽  
Number Flow ◽  
High Reynolds ◽  
Cryogenic Wind Tunnel ◽  
Effect Of Surface

In this paper, first, the principle, structures, operations, and performances of the cryogenic wind tunnel are described. By changing the pressure, temperature and velocity of gas a high Reynolds-number flow(5×104<Re<107)can be obtained. From the research results, a high Reynolds-number flow with comparatively low power, LN consumptions was attained. It was with Mach-number independent of each other, o show some examples of high Reynolds-number flow, the effects of surface roughness and grooves on the surface of a cylinder on the flow are measured using models with various values of roughness and size. A model test of an airship was also conducted. With the high Reynolds-number flow, the thickness of the boundary layer becomes thinner. Then the surface conditions of a body have great effect on the flow phenomena and on the drag of the body. Some attempts to reduce the drag of the body were shown.

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