scholarly journals Numerical Analysis of Printed Circuit Board with Thermal Vias: Heat Transfer Characteristics under Nonisothermal Boundary Conditions

2013 ◽  
Vol 03 (04) ◽  
pp. 136-143 ◽  
Author(s):  
Yasushi Koito ◽  
Yoshihiro Kubo ◽  
Toshio Tomimura
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Boundary Conditions ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Heat Transfer Characteristics ◽  
Printed Circuit ◽  
Transfer Characteristics

Numerical Analysis of Heat Transfer Characteristics in Microwave Heating of Magnetic Dielectrics

2011 ◽  
Vol 43 (3) ◽  
pp. 1070-1078 ◽  
Author(s):  
Zhiwei Peng ◽  
Jiann-Yang Hwang ◽  
Chong-Lyuck Park ◽  
Byoung-Gon Kim ◽  
Gerald Onyedika
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Microwave Heating ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Modeling of the Cavity Response to Rapid Transient Considering the Effect of Heat Transfer

2018 ◽  
Author(s):  
Shuiting Ding ◽  
Hang Yu ◽  
Tian Qiu ◽  
Chuankai Liu
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Heat Transfer Characteristics ◽  
Transient Responses ◽  
Transfer Characteristics ◽  
Thermal Boundary Conditions ◽  
Air System ◽  
Relative Errors ◽  
Low Dimensional ◽  
Rapid Transients

The internal air system, as one of the important subsystems of the aeroengine, is used to cooling and sealing, and plays a vital role in the safe operation of the engine. Especially in rapid transients, the complex dynamic response in air system may impose hazardous transition state loads on engine. Cavity is a component with pretty evident characteristics of transient in the air system due to the storage and release effects on the air. The flow and heat transfer characteristics of cavity should be made clear to precisely quantify the performance of the air system. The traditional study on cavity is based on the adiabatic assumption. However, the assumption is applicable to the transient of millisecond time scales physical phenomena in the air system, which is not usually common. Generally, the actual transition process is not instantaneous. Great discrepancies exist in the process of transition predicted by the adiabatic hypothesis compared with the practical process. The objective of this work is to propose a feasible method to solve the heat transfer issue throughout the transient process, which has not been settled by a proper method before, and develop a model for simulating the transient responses of the cavity with consideration of the heat transfer effect on the basis of the method. The model can predict transient responses under different thermal boundary conditions. Experiments have been developed for investigation of the charging process of the cavity. The thermal boundary can be controlled in the experiment, and the pressure and temperature responses of the cavity under different thermal boundary conditions have been analyzed. The non-dimensional numbers related to heat transfer characteristics were deduced by dimensional analysis, and the empirical formula of characteristics was proposed based on the experimental results. The non-adiabatic low-dimensional transient model of the cavity was established based on the heat transfer characteristics correlation. Results of transient responses calculated by non-adiabatic model were compared with the experimental data. It is found that both the transient responses of pressure and temperature agree well, with the maximum relative errors less than 2%. By comparison, the relative errors of pressure and temperature calculated by adiabatic model are about 8% and 12%, respectively. Meanwhile, the tendency of temperature response deviates from the actual process. Thus, the modeling method proposed is feasible and high-precision. The present work provides a technical method for establishing a low-dimensional model to describe the transient responses of the cavity with high accuracy, and supports the component-level modeling of the transient air system.

scholarly journals Numerical investigation of fluid flow and heat transfer characteristics on the aerodynamics of ventilated disc brake rotor using CFD

2014 ◽  
Vol 18 (2) ◽  
pp. 667-675 ◽  
Author(s):  
Karuppa Raj ◽  
R. Ramsai ◽  
J. Mathew ◽  
G. Soniya
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Heat Dissipation ◽  
Rotational Symmetry ◽  
Temperature Drop ◽  
Brake Disc ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Ansys Cfx ◽  
Brake Rotor

Ventilated brake discs are used in high speed vehicles. The brake disc is an important component in the braking system which is expected to withstand and dissipate the heat generated during the braking event. In the present work, an attempt is made to study the effect of vane-shape on the flow-field and heat transfer characteristics for different configurations of vanes and at different speeds numerically. Three types of rotor configurations circular pillared, modified taper radial and diamond pillar vanes were considered for the numerical analysis. A rotor segment of 20? was considered for the numerical analysis due to its rotational symmetry. The pre processing is carried out with the help of ICEM-CFD and analysis is carried out using ANSYS CFX 12.1. The three dimensional flow through the brake rotor vanes has been simulated by solving the appropriate governing equations viz. conservation of mass, momentum and energy using the commercial CFD tool, ANSYS CFX 12. The predicted results have been validated with the results available in the literature. Circular pillar rotor vanes are found to have more uniform pressure and velocity distribution which results in more uniform temperature drop around the vanes. The effect of number and diameter of vanes in the circular pillared rotor is studied and the geometry is optimized for better mass flow and heat dissipation characteristics.

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