The interior heat transfer characteristics of gas turbine blade due to sparse film cooling holes

2005 ◽  
Vol 34 (3) ◽  
pp. 197-207 ◽  
Author(s):  
Zhang Jingyu ◽  
Chang Haiping
Author(s):  
Elon J. Terrell ◽  
Brian D. Mouzon ◽  
David G. Bogard

Studies of film cooling performance for a turbine airfoil predominately focus on the reduction of heat transfer to the external surface of the airfoil. However, convective cooling of the airfoil due to coolant flow through the film cooling holes is potentially a major contributor to the overall cooling of the airfoil. This study used experimental and computational methods to examine the convective heat transfer to the coolant as it traveled through the film cooling holes of a gas turbine blade leading edge. Experimental measurements were conducted on a model gas turbine blade leading edge composed of alumina ceramic which approximately matched the Biot number of an engine airfoil leading edge. The temperature rise in the coolant from the entrance to the exit of the film cooling holes was measured using a series of internal thermocouples and an external traversing thermocouple probe. A CFD simulation of the model of the leading edge was also done in order to facilitate the processing of the experimental data and provide a comparison for the experimental coolant hole heat transfer. Without impingement cooling, the coolant hole heat transfer was found to account for 50 to 80 percent of the airfoil internal cooling, i.e. the dominating cooling mechanism.


Author(s):  
Yiwen Ma ◽  
Haiwang Li ◽  
Meisong Yang ◽  
Min Wu ◽  
Huimin Zhou

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.


1985 ◽  
Vol 107 (4) ◽  
pp. 991-997 ◽  
Author(s):  
C. Camci ◽  
T. Arts

This paper deals with an experimental investigation of heat transfer across the suction side of a high-pressure, film-cooled gas turbine blade and with an attempt to numerically predict this quantity both with and without film cooling. The measurements were performed in the VKI isentropic compression tube facility under well-simulated gas turbine conditions. Data measured in a stationary frame, with and without film cooling, are presented. The predictions of convective heat transfer, including streamwise curvature effects, are compared with the measurements. A new approach to determine the augmented mixing lengths near the ejection holes on a highly convex wall is discussed and numerical results agree well with experimentally determined heat transfer coefficients in the presence of film cooling.


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