Structure of Turbulent Flow in Subchannel of Rod Bundle Downstream of Spacer Grid With Hybrid Flow Mixing Device

2002 ◽  
Author(s):  
Dong Seok Oh ◽  
Wang Kee In ◽  
Tae Hyun Chun
Keyword(s):  
Rectangular Channel ◽  
Cross Flow ◽  
Mixing Efficiency ◽  
Lateral Velocity ◽  
Spacer Grid ◽  
Turbulent Diffusion Coefficient ◽  
Rod Bundle ◽  
Flow Mixing ◽  
A Cell ◽  
Rod Array

An experiment was performed in a wind tunnel to investigate the flow structure in a rod bundle with a hybrid vane grid. The hybrid vane is a flow-mixing device, which consists of two pairs of primary and secondary vanes in a cell. The test section is a rectangular channel (300 mm × 300 mm × 2400 mm) including 3 × 3 rod (75 mm diameter) array with a spacer grid. The pitch to diameter ratio of the rod array is 1.33. The flow structures downstream the grid are measured at Reynolds number of 1.2 × 105 for 35-degree deflecting angle of the hybrid flow-mixing vane. The data are obtained for the distributions of the time mean axial velocity, lateral velocity, and turbulent intensities in 3 component directions over a center subchannel along axial locations and compared with the previous results of split vane grid that has two vanes in a cell. The results show that the mixing efficiency of the hybrid vane grid could be similar with that of the split vane grid because swirl factor of the hybrid vane grid is higher than that of split vane grid and the magnitude of axial turbulent intensity, turbulent diffusion coefficient, and cross flow factor is similar to each other in spite of differences of the vane numbers and shape in a cell between hybrid and split vane grids.

Computational Fluid Dynamics Simulation of Flow-Mixing and Heat Transfer in 4 × 4 Rod Bundle With a Twist-Vane Spacer Grid

2019 ◽  
Vol 5 (4) ◽  
Author(s):  
Ganesh Lal Kumawat ◽  
Anuj Kumar Kansal ◽  
Naresh Kumar Maheshwari ◽  
Avaneesh Sharma
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Atomic Energy ◽  
Cfd Simulations ◽  
Spacer Grid ◽  
Fuel Rod ◽  
Rod Bundle ◽  
Flow Mixing ◽  
Computational Fluid Dynamics Cfd

The clearance between fuel rods is maintained by spacer grid or helical wire wrap. Thermal-hydraulic characteristics inside fuel rod bundle are strongly influenced by the spacer grid geometry and the bundle pitch-to-diameter (P/D) ratio. This includes the maximum fuel temperature, critical heat flux, as well as pressure drop through the fuel bundle. An understanding of the detailed structure of flow mixing and heat transfer in a fuel rod bundle geometry is therefore an important aspect of reactor core design, both in terms of the reactor's safe and reliable operation, and with regard to optimum power extraction. In this study, computational fluid dynamics (CFD) simulations are performed to investigate isothermal turbulent flow mixing and heat transfer behavior in 4 × 4 rod bundle with twist-vane spacer grid with P/D ratio of 1.35. This work is carried out under International Atomic Energy Agency (IAEA) co-ordinated research project titled as “Application of Computational Fluid Dynamics (CFD) Codes for Nuclear Power Plant Design.” CFD simulations are performed using open source CFD code OpenFOAM. Numerical results are compared with experimental data from Korea Atomic Energy Research Institute (KAERI) and found to be in good agreement.

scholarly journals Experimental studies of a single flexibly-mounted rod in a triangular rod bundle in cross-flow

2018 ◽  
Vol 148 ◽  
pp. 09002
Author(s):  
Sabine Upnere ◽  
Normunds Jekabsons ◽  
Sergejs Dementjevs ◽  
Michael Wohlmuther
Keyword(s):  
Experimental Studies ◽  
Cross Flow ◽  
Flow Induced Vibration ◽  
Rod Bundle ◽  
Rod System ◽  
Flow Induced Vibrations ◽  
The Stability ◽  
Paul Scherrer ◽  
Fixed Array ◽  
Rod Array

Experiments on flow-induced vibrations using a closely-packed triangular rod array with a pitch-todiameter ratio of 1.1 in water cross-flow was carried out at Paul Scherrer Institute. The bundle consists of 21 row of five rods in each one. Single flexibly-mounted test rod (TR) is in the fourth row in an otherwise fixed array. The test rod can freely move in the transverse and in-line direction. Two accelerometer sensors were attached at both ends of the TR to measure the rod response on the fluid flow. The effect of flow rate on the stability of the flexibly-mounted TR has been analysed. During experiments, it reveals a set of conditions and tendencies for the flow-induced vibration in the closely-packed multi-rod system.

Flow and Temperature Fields Measurement Inside Rod Bundle by the Combined Use of PIV and LIF Technique

2018 ◽  
Author(s):  
Xing Li ◽  
Sichao Tan ◽  
Zhengpeng Mi ◽  
Peiyao Qi ◽  
Yunlong Huang
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Great Influence ◽  
Reactor Core ◽  
Transfer Characteristic ◽  
Index Of Refraction ◽  
Temperature Fields ◽  
Spacer Grid ◽  
Rod Bundle ◽  
Combined Use

Thermal hydraulic research of reactor core is important in nuclear energy applications, the flow and heat transfer characteristics of coolant in reactor fuel assembly has a great influence on the performance and safety of nuclear power plants. Particle image velocimetry (PIV) and Laser induced fluorescence (LIF) are the instantaneous, non-intrusive, whole-field fluid mechanics measuring method. In this study, the simultaneous measurement of flow field and temperature field for a rod bundle was conducted using PIV and LIF technique. A facility system, utilizing the matching index of refraction approach, has been designed and constructed for the measurement of velocity and temperature in the rod bundle. In order for further study on complex heat and mass transfer characteristic of rod bundle, the single-phase experiments on the heating conditions are performed. One of unique characteristics of the velocity and temperature distribution downstream the spacer grid was obtained. The experimental results show that the combined use of PIV and LIF technique is applied to the measurement of multi-physical field in a rod bundle is feasible, the measuring characteristics of non-intrusive ensured accuracy of whole field data. The whole field experimental data obtained in rod bundle benefits the design of spacer grid geometry.

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