Coolant Flow Distribution and Pressure Loss in ONAN Transformer Windings—Part I: Theory and Model Development

2004 ◽  
Vol 19 (1) ◽  
pp. 186-193 ◽  
Author(s):  
J. Zhang ◽  
X. Li
Keyword(s):  
Pressure Loss ◽  
Model Development ◽  
Flow Distribution ◽  
Coolant Flow ◽  
Theory And Model

Role of Complicated Flow Fields in Lower Plenum on Coolant Flow Distribution to Core of ABWR

2012 ◽  
Author(s):  
Shun Watanabe ◽  
Yutaka Abe ◽  
Akiko Kaneko ◽  
Fumitoshi Watanabe ◽  
Kazuki Hirao
Keyword(s):  
Numerical Simulation ◽  
Pressure Loss ◽  
Flow Distribution ◽  
Coolant Flow ◽  
Flow Structures ◽  
Cfd Analysis ◽  
The Core ◽  
Flow Experiment ◽  
Power Outputs

In order to achieve increase of power outputs of an ABWR, it is extremely important to evaluate coolant flow in a lower plenum. Numerical simulation is helpful to predict the coolant flow, and thus verification experiments are needed. Hence, the present study is focusing on the construction of benchmark of CFD code. The objective of the study is to clarify relation between flow distribution to the core and the complicated flow structures in the lower plenum. We constructed a 1/10 model of a lower plenum to conduct flow experiment for validation of CFD analysis. In the experiment, it turned out that coolant flow distribution becomes to be uniform at core support beam, and there are complicated flows like vortices around side entry orifices. Regarding differential pressure distribution, it was revealed that profile of the region including side entry orifices is very dominant. This pressure loss might be caused by contraction flow at the orifices. Such flow structures were also described by CFD analysis. As good performance of analysis, we investigated flow distribution to the core particularly by using CFD results. And relation between the flow distribution and the complicated flow structures were also discussed.

Study on Pressure Loss Induced by Complicated Flow Through Lower Plenum of BWR

2010 ◽  
Author(s):  
Shun Watanabe ◽  
Yutaka Abe ◽  
Akiko Kaneko ◽  
Fumitoshi Watanabe ◽  
Kenichi Tezuka
Keyword(s):  
Flow Structure ◽  
Pressure Loss ◽  
Nuclear Power ◽  
Flow Distribution ◽  
Velocity Profiles ◽  
Differential Pressure ◽  
Coolant Flow ◽  
Fluid Behavior ◽  
Piv Measurement ◽  
Power Outputs

One of the strategies of cost reduction of nuclear power generation is the increase of power outputs. Especially, in order to achieve performance upgrade of Advanced Boiling Water Reactor (ABWR), it is extremely important to evaluate coolant flow in the lower plenum of ABWR. With the plenty construction in the lower plenum, it is thought that the flow structure is complicated. Moreover, according to the previous studies, there is strong evidence that vortexes arise around side entry orifice when coolant flows in there. Such complicated flow may affect the pressure loss (differential pressure in the lower plenum) and the coolant flow distribution to each core fuel assemblies, and consequently it would influence advancement of fuel economics. Although the simulation results by a CFD code can predict such complicated flow in the lower plenum, the accuracy of simulation data are not enough. Hence, the present study is focusing on the establishment of the benchmark of CFD code by using the visualization method in the lower plenum of ABWR. The objective of the present study is to investigate correlation between the structure of vortexes and complicated flow in upstream of core support beam, and the effect of such fluid behavior to the differential pressure. In the constructed model of the lower plenum of ABWR, velocity profiles were measured by LDV (Laser Doppler Velocimetry) and PIV (Particle Image Velocimetry) techniques. And differential pressure of constructed model is measured by differential pressure instrument. Each measurement was worked out in the range of Reynolds number from 103 to 104. It was found from the LDV measurement that the velocity at the center of the test section was faster than that near the wall in upstream. In downstream, the velocity profiles showed the tendency to be flat in the core support beam. Vortexes were observed around side entry orifice by PIV measurement. Concerning differential pressure, it is necessary to examine correlation between complicated flow structure and differential pressure. Thus in the present study, the differential pressure distribution of constructed model is experimentally investigated.

A Highly Efficient Integrated Silicon-Microchannel Cooler for Multi-Module Electronic Microsystems-Model Design, Optimization and Performance Validation

2020 ◽  
pp. 1-38
Author(s):  
Jiejun Wang ◽  
Tao Wang ◽  
Qiuyan Li ◽  
Yiming Li ◽  
Chuangui Wu ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flow Distribution ◽  
Development Trend ◽  
High Heat ◽  
Coolant Flow ◽  
Maximum Temperature ◽  
High Heat Flux ◽  
Highly Efficient ◽  
And Performance ◽  
Performance Validation

Abstract Recently, the development trend of multi-module and multi-function in electronic microsystems makes the ever-increasing heat flux problem more serious. In this study, a highly efficient integrated single-phase microchannel cooler with four heat sources is presented for handling the challenges from both working independently of all electronic modules and the high heat flux. Numerical and experimental study are both conducted. By optimizing the structural design and the fabricated process, the presented microchannel cooler has outstanding cooling performance, which contains desired fluid flow distribution, pressure drop, heat transfer and combination thereof. Results reveals uniform coolant flow dissipates four individual heaters independently, and their maximal temperature difference below 4 °C. Beyond this, high heat flux removal (707.6 W/cm2) is realized with extremely low coolant flow rate (45 ml/min), and the maximum temperature rise is less than 60 °C. This study provides a referable solution for the thermal management of multi-module heat source and high heat flux in compact electronic microsystems.

Optimization of a Large Injection System for Steam Turbines

2015 ◽  
Author(s):  
Leonardo Nettis ◽  
Enzo Imparato ◽  
Lorenzo Cosi
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Flow Distribution ◽  
Low Pressure ◽  
Total Pressure Loss ◽  
Injection System ◽  
Steam Turbines ◽  
Original Design ◽  
Design And Optimization ◽  
Large Injection

Steam turbines are applied in production plants characterized by very large injections of low pressure steam. For this reason the design and optimization of the injection section is fundamental to obtain an adequate level of turbine efficiency and ensure uniform flow at the inlet of the low pressure stages downstream the injection. This paper illustrate the optimization performed on a Steam Turbine injection system for a unit in which injection flow is 80% of the total outlet mass flow. Optimization was performed varying the shape of the original steam guide with the twofold objective of minimizing the total pressure loss and uniform the circumferential flow distribution. The analysis has been performed using RANS 2D and 3D CFD solver. The design process has been structured in 3 different steps: i) Axisymmetric CFD screening based on DOE ii) 3D-CFD verification of the profile shape previously obtained with the additional estimation of the flow uniformity on 360° iii) 3D-CFD of the injection module including the reaction stage upstream and the first LP stage downstream, with the stator modeled on 360°. The main outcomes are presented in terms of total pressure loss and uniformity of circumferential flow, both strongly reduced with respect to the original design. Moreover in order to characterize the excitation associated with flow non-uniformity an analysis in the frequency domain of the flow distribution has been performed.

scholarly journals Cooling Characteristics of Film Cooled Turbine Vane Having Multi-Row of Ejection Holes

1978 ◽  
Author(s):  
K. Sakata ◽  
H. Usui ◽  
K. Takahara
Keyword(s):  
Flow Distribution ◽  
Leading Edge ◽  
Coolant Flow ◽  
Edge Region ◽  
Flow Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Turbine Vanes ◽  
Turbine Vane ◽  
Cooling Hole

Film-cooled turbine vanes having 14 rows of round holes were designed. Two-dimensional cascade tests of two kinds of scaled vanes were carried out and cooling performances were obtained. Coolant flow distributions were controlled by the impingement and plenum chamber configuration. Higher cooling effectiveness than 0.65 was obtained for the coolant flow ratio of 4.5 percent. And it was clarified that the distributions of cooling effectiveness of the vane surface was governed by the configuration of coolant flow distribution to the cooling hole rows, and, that with using relatively greater amount of coolant to the leading edge region, higher cooling performance can be obtained. Also, numerical calculations of cooling performance and prediction for turbine application were presented.

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