scholarly journals Study on heat transfer characteristics of hollow composite thermal barrier structure at high temperature

AIP Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 065005
Author(s):  
Yingjie Liu ◽  
Xiangwei Liao ◽  
Minggang Shen ◽  
Xiaolei Zhu ◽  
Kun Liu
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Thermal Barrier ◽  
Barrier Structure ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

A Thermal Barrier With Adaptive Heat Transfer Characteristics

1994 ◽  
Vol 116 (2) ◽  
pp. 302-310 ◽  
Author(s):  
P. Furmanski ◽  
J. M. Floryan
Keyword(s):  
Heat Transfer ◽  
Heat Flow ◽  
Volume Fraction ◽  
Large Temperature ◽  
Thermal Barrier ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Apparent Slip ◽  
Small Volume Fraction ◽  
Relative Thermal Conductivity

A thermal barrier with adaptive heat transfer characteristics for applications in zero gravity environments is considered. The barrier consists of a mixture of fluid with a small volume fraction of arbitrarily oriented, randomly distributed particles of ellipsoidal shape. Heat flux control is obtained by changing the orientation of the particles. Heat flow may be increased up to several hundred times by rotating the particles from being parallel to the walls to being transverse to the walls and by increasing their aspect ratio, volume fraction, and relative thermal conductivity. An increase in the size of the particles results in the appearance of wall effects, which may substantially reduce heat flow as compared to the case of an infinite medium. Very large temperature variation is found to occur near the walls where an apparent “slip” of temperature occurs for barriers whose thickness is large compared to the particle size.

scholarly journals Heat transfer in a novel microwave heating device coupled with atomization feeding

2021 ◽  
pp. 288-288
Author(s):  
Shangzhi Yu ◽  
Qinglong Xie ◽  
Xiaoning Mao ◽  
Ying Duan ◽  
Yong Nie
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
High Temperature ◽  
Microwave Heating ◽  
Flow Rate ◽  
Orifice Diameter ◽  
Spray Parameters ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Spray Flow Rate

The heat transfer characteristics of the microwave heating coupled with atomization feeding were investigated using ethanol as the spray medium on a pressure swirl nozzle. The effects of spray height, flow rate and temperature on the sauter mean diameter (SMD) of atomized droplets were examined. The results showed that the droplet SMD was 12-130 ?m, which increased with the spray height and decreased with the flow rate and temperature of spray medium. Through the fitting of the experimental data, the dimensionless correlation of the droplet SMD which was based on orifice diameter, Reynolds and Ohnesorge numbers was obtained. The calculated results were basically consistent with the experimental data within 15% error. The heat transfer characteristics of atomized droplets on high-temperature surface of SiC bed heated by microwave were then investigated. The effects of spray flow rate, spray height and spray temperature on the heat transfer characteristics were examined. The power of spray heat transfer decreased with the temperature and increased with the spray flow rate and spray height. The dimensionless correlation to describe the heat transfer characteristics of atomized droplets on the high-temperature SiC surface under the microwave heating was obtained which included thermophysical properties of spray medium, spray parameters, and temperatures of the high-temperature bed surface and spray medium, with the error of ?20%. These correlations can be used to predict the SMD of the atomized droplets and the power of spray heat transfer in the microwave heating process.

Numerical Study on Influencing Factors of Film Cooling on Turbine Blade Leading Edge Under Rotating State

2018 ◽  
Author(s):  
Yiwen Ma ◽  
Haiwang Li ◽  
Meisong Yang ◽  
Min Wu ◽  
Huimin Zhou
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Turbine Blade ◽  
Rotation Number ◽  
Film Cooling ◽  
Leading Edge ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Blade Leading Edge

Engine turbine blades operate at a high speed of rotation and are subjected to high temperature and pressure prevailing gas from the combustion chamber, making the working condition very harsh. In particular, the leading edge of the blade, which is directly subjected to high-temperature gas impacts, is the hottest part of the turbine. Therefore, it is of great importance to improve the protection of the blade leading edge and enhance the understanding of this part of the flow field and temperature field. This paper will focus on the phenomenon of wake deflection and study the film cooling characteristics of the turbine blade under rotating condition. The characteristics of pressure surface and suction surface of the blade are verified by numerical simulation. The contents cover the influence of the film hole diameter, pitch, blowing ratio, rotation number and the development process, the film cooling efficiency on the outflow of coolant film. The result shows that Coriolis force, centrifugal force and secondary flow induced by rotation will change the mainstream flow along the blade, which will lead to changes of pattern concerning the development of the film on the blade surface. In the process of wake development, deflection occurs in different directions at different positions, and the greater the rotation number is, the more obvious the degree of deflection will be. Studying the model with film holes on the leading edge of the blade, these phenomena can be observed along the downstream on the pressure and suction surfaces. Also, models with film holes independently set on the pressure and suction surfaces can be used as proof of these features. At the same time, this paper studies the flow and heat transfer characteristics of the leading-edge gas film under rotating condition and focuses on the influence of rotation on the outflow and the development processes of the wake. The gas film cooling models in rotating state of different film hole diameters and film hole radial spacing will also be compared to further understand the flow and heat transfer characteristics of film cooling on the leading edge of the blade.

Sign in / Sign up

Export Citation Format

Share Document