Thermal-Fluid Analysis of Steady-Flow Devices

2020 ◽  
pp. 452-524
Keyword(s):  
Steady Flow ◽  
Fluid Analysis ◽  
Thermal Fluid Analysis ◽  
Flow Devices

scholarly journals A Coupled, Semi-Numerical Model for Thermal Analysis of Medium Frequency Transformer

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 328 ◽  
Author(s):  
Haonan Tian ◽  
Zhongbao Wei ◽  
Sriram Vaisambhayana ◽  
Madasamy Thevar ◽  
Anshuman Tripathi ◽  
...  
Keyword(s):  
Numerical Model ◽  
Analytical Model ◽  
Electromagnetic Analysis ◽  
Medium Frequency ◽  
Fluid Analysis ◽  
Fluid Behavior ◽  
Proposed Model ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Thermal Fluid Analysis

Medium-frequency (MF) transformer has gained much popularity in power conversion systems. Temperature control is a paramount concern, as the unexpected high temperature declines the safety and life expectancy of transformer. The scrutiny of losses and thermal-fluid behavior are thereby critical for the design of MF transformers. This paper proposes a coupled, semi-numerical model for electromagnetic and thermal-fluid analysis of MF oil natural air natural (ONAN) transformer. An analytical model that is based on spatial distribution of flux density and AC factor is exploited to calculate the system losses, while the thermal-hydraulic behavior is modelled numerically leveraging the computational fluid dynamics (CFD) method. A close-loop iterative framework is formulated by coupling the analytical model-based electromagnetic analysis and CFD-based thermal-fluid analysis to address the temperature dependence. Experiments are performed on two transformer prototypes with different conductor types and physical geometries for validation purpose. Results suggest that the proposed model can accurately model the AC effects, losses, and the temperature rises at different system components. The proposed model is computationally more efficient than the full numerical method but it reserves accurate thermal-hydraulic characterization, thus it is promising for engineering utilization.

Automatic Thermal Modeling for System Level Design of Electronic Equipment

2003 ◽  
Author(s):  
Kenichiro Aoki ◽  
Koichi Shimizu ◽  
Akira Ueda ◽  
Akira Tamura ◽  
Masanori Motegi
Keyword(s):  
Model Building ◽  
Software Tool ◽  
System Level ◽  
Analysis Model ◽  
Accurate Analysis ◽  
Fluid Analysis ◽  
Analytical Accuracy ◽  
Thermal Fluid Analysis ◽  
Short Time ◽  
Large Investment

The development of hardware needs cost reduction by shortening a development period and reducing experimental man-hour. In order to satisfy these demands, thermal fluid analysis with higher accuracy in short time is indispensable for product development. At present, thermal fluid analyses are conducted using different software tools. Each software tool requires model building and meshing for simulations using its own format. That leads to a large investment in time, and therefore cost. VPS/Simulation-Hub software Fujitsu developed is able to convert data from various CADs. It has the features to create a data fitting to numerical analysis software, create an accurate analysis model, and delete unnecessary components. With these main features, VPS/Simulation-Hub greatly contributes to the man-hour reduction for model building and the improvement of analytical accuracy. In this paper, VPS/Simulation-Hub is introduced with the detail explanation of the above 3 main features.

INVESTIGATION OF TEMPERATURE RISING MECHANISM IN LONG TUNNEL BY NUMERICAL SIMULATION

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Haeyoung Kim ◽  
Hitoshi Yamada ◽  
Hiroshi Katsuchi ◽  
Soichiro Nakamura
Keyword(s):  
Wind Speed ◽  
Cross Flow ◽  
Initial Condition ◽  
The Past ◽  
Fluid Analysis ◽  
Tunnel Section ◽  
Reduction Effect ◽  
Thermal Fluid Analysis ◽  
Ventilation Fan

Abnormally high temperature inside the long, undergrounded tunnel is a problem in the urban area. As one of the countermeasures, a ventilation fan has been operated. However, the insufficient temperature reduction effect and high cost are an issue and improvement is required. In this study, in order to improve the operating plan of ventilation, the flow field and temperature distribution characteristics are clarified by computational thermal fluid analysis, and the operation of the optimum ventilation was decided. The dominant factors for the temperature rising were identified as traffic volume, lane axis wind speed, cross flow ventilation, and heat flux between tunnel body and air in tunnel. In the analysis, we focused on these four factors, and applied these factors obtained from long-term on-site measurement to the boundary condition and the initial condition. In addition, the amount of heat from vehicle traffic was calculated based on the measurement and the past report results. The analytical model is 1000 m partial tunnel section where the temperature rising was intense. The validation of numerical model was verified from the comparison between the analysis results and the measured values. It was confirmed that the effect of increasing lane axis wind speed as a countermeasure was not significant, and the ventilation amount of crosswind is recommended as 60 m3/s.

Thermal fluid analysis in a wheelchair marathon

2018 ◽  
Vol 2018 (0) ◽  
pp. A-7
Author(s):  
Satoshi TSUJI ◽  
Masaki HIRATSUKA ◽  
Shinichiro ITO
Keyword(s):  
Fluid Analysis ◽  
Thermal Fluid Analysis

scholarly journals Heat Transfer and Thermal Management of Interior Permanent Magnet Synchronous Electric Motor

Inventions ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 69
Author(s):  
Pey-Shey Wu ◽  
Min-Fu Hsieh ◽  
Wei Ling Cai ◽  
Jen-Hsiang Liu ◽  
Yun-Ting Huang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Electric Motor ◽  
Thermal Field ◽  
Water Jacket ◽  
Taylor Flow ◽  
Nusselt Numbers ◽  
Fluid Analysis ◽  
Interior Permanent Magnet ◽  
Thermal Fluid Analysis ◽  
Spiral Channel

Geometric complexities and multi-physical phenomena add difficulties for predicting the thermal field and hence thermal management of an electric motor. A numerical design model that combined electromagnetic and thermal-fluid analysis was proposed for disclosing the detailed temperature distributions of each component in an electric motor. The thermal fluid analysis implemented ANSYS-Fluent code to unravel the thermal field of the interior permanent magnet synchronous electric motor fitted with a smooth or novel spirally twisted channel in the cooling water jacket of a stator with and without shaft cooling. In accordance with the thermal powers converted from the various electromagnetic losses of the electric motor, the complex heat conduction model with realistic thermal boundary conditions was formulated. Initially, the turbulent flow structures and channel averaged Nusselt numbers of the spiral channels without and with the sectional twist were comparatively examined for acquiring the convective thermal boundary conditions in the water jacket. With the high thermal conductivity of the aluminum water jacket, the heat-transfer improvements from the smooth-spiral-channel conditions by using the twisted spiral channel were effective for reducing the average temperatures by about 10% but less effective for altering the characteristic thermal field in the water jacket. At 1290 < Dn < 6455 or 5000 < Re < 25,000 for the spiral channel flows, the channel average Nusselt numbers ratios between the smooth and twisted spiral channels were elevated to 1.18–1.09 but decreased with the increase of Dn or Re. A set of heat-transfer correlations for estimating the Nusselt numbers of Taylor flow in the rotor-to-stator air gap was newly devised from the data available in the literature. While the cooling effectiveness of the water jacket and shaft was boosted by the sectional twists along the spiral channel of the water jacket, the presence of Taylor flow in the annual air gap prohibited the effective rotor-to-stator heat transmission, leading to hot spots in the rotor. By way of airflow cooling through the rotating hollow shaft, the high temperatures in the rotor were considerably moderated. As the development of Taylor flow between the rotor and stator was inevitable, the development of active or passive rotor cooling schemes was necessary for extending the power density of an electric motor. Unlike the previous thermal circuit or lumped-parameter thermal model that predicted the overall temperatures of motor components, the present coupled electromagnetic and thermal-fluid model can reveal the detailed temperature distributions in an electric motor to probe the local hot spots of each component in order to avoid overheating at the early design stage.

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