Heat transfer and friction in segmental turbine blade cooling channels

10.2514/3.925 ◽  
1997 ◽  
Vol 11 ◽  
pp. 486-488
Author(s):  
N. W. M. Ko ◽  
R. C. K. Leung ◽  
K. Lam ◽  
R. B. Spence ◽  
S. C. Lau
Author(s):  
Akshay Khadse ◽  
Andres Curbelo ◽  
Ladislav Vesely ◽  
Jayanta S. Kapat

Abstract The first stage of turbine in a Brayton cycle faces the maximum temperature in the cycle. This maximum temperature may exceed creep temperature limit or even melting temperature of the blade material. Therefore, it becomes an absolute necessity to implement blade cooling to prevent them from structural damage. Turbine inlet temperatures for oxy-combustion supercritical CO2 (sCO2) are promised to reach blade material limit in near future foreseeing need of turbine blade cooling. Properties of sCO2 and the cycle parameters can make Reynolds number external to blade and external heat transfer coefficient to be significantly higher than those typically experience in regular gas turbines. This necessitates evaluation and rethinking of the internal cooling techniques to be adopted. The purpose of this paper is to investigate conjugate heat transfer effects within a first stage vane cascade of a sCO2 turbine. This study can help understand cooling requirements which include mass flow rate of leakage coolant sCO2 and geometry of cooling channels. Estimations can also be made if the cooling channels alone are enough for blade cooling or there is need for more cooling techniques such as film cooling, impingement cooling and trailing edge cooling. The conjugate heat transfer and aerodynamic analysis of a turbine cascade is carried out using STAR CCM+. The turbine inlet temperature of 1350K and 1775 K is considered for the study considering future potential needs. Thermo-physical properties of this mixture are given as input to the code in form of tables using REFPROP database. The blade material considered is Inconel 718.


1972 ◽  
Vol 94 (1) ◽  
pp. 51-58 ◽  
Author(s):  
W. Tabakoff ◽  
W. Clevenger

An experimental investigation of heat transfer characteristics for various configurations of air jets impinging on the leading edge inner surface of the blade wall is presented. Three configurations were investigated, namely a slot jet, a round jet row and an array of round jets. The effect on the heat transfer coefficient of injecting solid particles into the air flow is considered. The study treats an important class of turbine blade cooling for which small cooling mass flow rates are of interest. The experimental facility and procedures are described in detail. A theoretical technique is introduced for predicting the heat transfer in the case of the slot jet configuration. The results are compared to experimental data.


Author(s):  
Mohammad Alizadeh ◽  
Ali Izadi ◽  
Alireza Fathi ◽  
Hiwa Khaledi

Modern turbine blades are cooled by air flowing through internal cooling passages. Three-Dimensional numerical simulation of these blade cooling passages is too time-consuming because of their complex geometries. These geometrical complexities exist as a result of using various kinds of cooling technologies such as rib turbulators (inline, staggered, or inclined ribs), pin fin, 90 and 180 degree turns (both sharp and gradual turns, with and without turbulators), finned passage, by-pass flow and tip cap impingement. One possible solution to simulate such sophisticated passages is to use the one-dimensional network method, which is presented in the current work. Turbine blade cooling channels are flow passages having multiple inlets and exits. The present in-house developed solver uses a network method for analyzing such a complicated flow pattern. In this method, cooling system is represented by a network of elements connected together at different nodes. Using assumed wall temperature, internal flow and heat transfer is calculated. The final goal of this computation is a set of boundary conditions for conjugate blade heat transfer simulation (coolant side boundary conditions). For validation, it is required to use experimental data that include temperature distribution of blade coolant-side walls. Since there is no experimental work with such data in the open literature, numerical computation is validated using available analytical and published numerical data. Calculated results agree well with analytical and numerical data. In order to exhibit the potential capabilities of the developed code, flow and heat transfer in a complicated internal cooling passage of a typical vane are investigated using the network method.


Author(s):  
Nafiz H. K. Chowdhury ◽  
Hootan Zirakzadeh ◽  
Je-Chin Han

The growing trend to achieve a higher Turbine Inlet Temperature (TIT) in the modern gas turbine industry requires, in return, a more efficient and advanced cooling system design. Therefore, a complete study of heat transfer is necessary to predict the thermal loadings in the turbine vane/blade. To estimate the metal temperatures, it is important to simulate the external hot gas flow condition, the conduction in the blade material, and the internal coolant flow characteristics accurately and simultaneously. As a result, proposing novel, quicker, and more convenient ways to study the heat transfer behavior of gas turbine blades is of absolute necessity. In the current work, a predictive model for the gas turbine blade cooling analysis in the form of a computer program has been developed to answer this need. The program is capable of estimating distribution of coolant mass flow rate, internal pressure and metal temperature of a turbine blade based on external and internal boundary conditions. The simultaneous solutions result from the coupled equations of mass and energy balance. The model is validated by showing its accuracy to predict the temperature distributions of a NASA E3 blade with an uncertainty of less than +/−10%. Later, this paper documents the overall analysis for a set of different boundary conditions with the same blade model (E3) and demonstrates the capability of the program to extend for other cases as well.


Author(s):  
A. S. Kenkare ◽  
T. M. Kilner

Although turbine blade cooling has consistently led to the use of higher turbine inlet temperatures leading to improved cycle efficiencies, very little of this technology has found its way into undergraduate laboratory work. The cost of modern blade heat transfer research rigs virtually rules out the possibility of introducing this topic in undergraduate teaching laboratories of Universities or Polytechnics in the UK operating within tight budgetary constraints. However, the underlying principles of blade cooling heat transfer may be demonstrated quite easily by using inlet temperatures about half those existing in the actual turbine and the paper describes the design and development of a low-cost blade cooling heat transfer rig. Test results obtained on the ‘model’ rig enable an appreciation of the problems encountered in turbine blade cooling to be made and may serve as a basis for the design and development of more complicated blade cooling systems.


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