Enhancing flow pattern upstream of New Hafeer Pump Station

Abstract A physical model with a scale of 1:20 was used to study the hydraulic characteristics of the flow in the forebay area of the pump station in Tian Wan Nuclear Power Plant Project Unit 5&6. The original layout scheme of the pump station forebay is limited by space, the turning radius of the intake gallery is small and the straight line section is short, the uniformity of water distribution is poor after seawater enters the forebay, the flow in the forebay cannot fully diffuse, the mainstream is concentrated, the flow distribution in the inlet section of each channel of the pump station is uneven, and the flow pattern is poor. Firstly, the distribution of water flow and uniformity of water distribution in the pump station forebay under different turning radius of tunnel are compared, and the turning radius of intake corridor is determined by calculating the head loss in different parts of tunnel. A variety of rectification facilities are arranged in the pumping station forebay, including modifying the grid type, setting diversion wall, diversion plate, energy dissipation beam, rectification bottom sill, etc. The recommended scheme is determined by hydraulic model test. The scheme can satisfy the requirement of uniformity of water distribution in the forebay, and the flow pattern along each section of the channel is also good.

Download Full-text

Numerical Simulation on the Flow Pattern in Forebay of Pumping Station

Volume 2: Applied Fluid Mechanics; Electromechanical Systems and Mechatronics; Advanced Energy Systems; Thermal Engineering; Human Factors and Cognitive Engineering ◽

10.1115/esda2012-82059 ◽

2012 ◽

Author(s):

Chao Liu ◽

Meining Lu

Keyword(s):

Numerical Simulation ◽

Flow Field ◽

Flow Pattern ◽

Turbulence Model ◽

Original Design ◽

3D Flow ◽

Diffusion Channel ◽

Pump Station ◽

Fluent Software ◽

Simulation Results

Based on FLUENT software, the standard k–ε turbulence model is adopted to simulate 3D-flow field in the forebay of a combined sluice-pump station. Flow field of the diffusion channel and suction passage is obtained after numerical simulation. Results show that flow in the fore-bay appears side-direction and vortexes exist in it and inlet of the suction passage. According to the results, optimum measures such as changing the wing wall form, extending the sluice pier, adding tri-prisms are conducted on the basis of original design. The vortexes are eliminated finally. Flow in diffusion channel appears front inflow and is improved effectively.

Download Full-text

Morphology and development of flow-pattern defect with extended nonagitated Secco etching

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172073 ◽

1994 ◽

Vol 52 ◽

pp. 868-869

Author(s):

Y. Pan

Keyword(s):

Flow Pattern ◽

Silicon Crystal ◽

Gate Oxide ◽

Crystal Growth Rate ◽

Etch Depth ◽

Force Microscopy ◽

Etch Pit ◽

Float Zone ◽

Atomic Force ◽

Multiple Step

The D defect, which causes the degradation of gate oxide integrities (GOI), can be revealed by Secco etching as flow pattern defect (FPD) in both float zone (FZ) and Czochralski (Cz) silicon crystal or as crystal originated particles (COP) by a multiple-step SC-1 cleaning process. By decreasing the crystal growth rate or high temperature annealing, the FPD density can be reduced, while the D defectsize increased. During the etching, the FPD surface density and etch pit size (FPD #1) increased withthe etch depth, while the wedge shaped contours do not change their positions and curvatures (FIG.l).In this paper, with atomic force microscopy (AFM), a simple model for FPD morphology by non-crystallographic preferential etching, such as Secco etching, was established.One sample wafer (FPD #2) was Secco etched with surface removed by 4 μm (FIG.2). The cross section view shows the FPD has a circular saucer pit and the wedge contours are actually the side surfaces of a terrace structure with very small slopes. Note that the scale in z direction is purposely enhanced in the AFM images. The pit dimensions are listed in TABLE 1.

Download Full-text