scholarly journals Mathematical modeling of coupled heat transfer on cooled gas turbine blades

2020 ◽  
Vol 12 (S) ◽  
pp. 193-200
Author(s):  
Ying SUN ◽  
Sergey A. KOLESNIK ◽  
Ekaterina L. KUZNETSOVA

The paper presents a physico-mathematical model for determining the heat transfer parameters between viscous gasdynamic flotations and cooled gas turbine blades made using the technology of composite permeable membranes (CPM). The mathematical model includes equations of dynamic and thermal boundary layers taking into account injection, three-dimensional transient heat conduction in CPM cooled frames, complex hydraulic flow and cooling inside the channels of a cooled blade with air taken from the power plant compressor. A complex problem was solved to determine the thermal state of microrocket engines, where a method was proposed for immersing a multiply-connected domain in a region of the simplest form. A new economical, absolutely stable method is proposed for numerically solving of spatial nonstationary heat transfer problems in multiply-connected domains. The results obtained showed greater cooling efficiency at lower cooling medium costs.

2009 ◽  
Vol 30 (13) ◽  
pp. 1077-1086 ◽  
Author(s):  
Peter Heidrich ◽  
Jens V. Wolfersdorf ◽  
Martin Schnieder

1986 ◽  
Vol 108 (1) ◽  
pp. 116-123 ◽  
Author(s):  
K. Rued ◽  
S. Wittig

The accurate prediction of heat transfer coefficients on cooled gas turbine blades requires consideration of various influence parameters. The present study continues previous work with special efforts to determine the separate effects of each of several parameters important in turbine flow. Heat transfer and boundary layer measurements were performed along a cooled flat plate with various freestream turbulence levels (Tu = 1.6−11 percent), pressure gradients (k = 0−6 × 10−6), and cooling intensities (Tw/T∞ = 1.0−0.53). Whereas the majority of previously available results were obtained from adiabatic or only slightly heated surfaces, the present study is directed mainly toward application on highly cooled surfaces as found in gas turbine engines.


2021 ◽  
pp. 111-116
Author(s):  
И.К. Андрианов ◽  
М.С. Гринкруг

Работа посвящена исследованию проблемы управления тепловым состоянием оболочечных лопаток судовых турбин, находящихся в условиях высокотемпературного нагружения. В работе рассматривались вопросы сочетания внешней тепловой защиты с помощью теплоизоляционного покрытия и внутреннего охлаждения. Математическая модель теплопереноса строилась на основании дифференциальных уравнений теплопроводности Фурье, условия теплоотдачи в каналах охлаждения. Проведена оценка влияния состава покрытия не изменение формы оболочки дефлектора с целью интенсификации охлаждения при неизменных параметрах скорости и температуры хладагента на входе в канал. Решение системы нелинейных уравнений теплопереноса проведено с помощью метода конечных разностей. Проведен численный эксперимент при реализации равномерного температурного поля на поверхности тела лопатки. Предложенная математическая модель позволяет рассчитать геометрию дефлекторов охлаждаемых лопаток судовых газовых турбин. Применение модели и результатов расчетов позволит рационализировать процесс охлаждения лопаток турбин, выбирая оптимальные сочетания внешней тепловой защиты и расхода хладагента. The work is devoted to the study of the problem of controlling the thermal state of the shell blades of marine turbines under high-temperature loading conditions. The paper deals with the combination of external thermal protection with the help of thermal insulation coating and internal cooling. The mathematical model of heat transfer was built on the basis of the Fourier differential equations of thermal conductivity, the conditions of heat transfer in cooling channels. The influence of the coating composition on the change in the shape of the deflector shell was evaluated in order to intensify cooling at constant parameters of the speed and temperature of the refrigerant at the inlet to the channel. The solution of the system of nonlinear heat transfer equations is carried out using the finite difference method. A numerical experiment is performed for the realization of a uniform temperature field on the surface of the blade body. The proposed mathematical model allows us to calculate the geometry of the deflectors of the cooled blades of marine gas turbines. The application of the model and the results of the calculations will allow to rationalize the cooling process of the turbine blades, choosing the optimal combination of external thermal protection and refrigerant consumption.


2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Abdel Rahman Salem ◽  
Farah Nazifa Nourin ◽  
Mohammed Abousabae ◽  
Ryoichi S. Amano

Abstract Internal cooling of gas turbine blades is performed with the combination of impingement cooling and serpentine channels. Besides gas turbine blades, the other turbine components such as turbine guide vanes, rotor disks, and combustor wall can be cooled using jet impingement cooling. This study is focused on jet impingement cooling, in order to optimize the coolant flow, and provide the maximum amount of cooling using the minimum amount of coolant. The study compares between different nozzle configurations (in-line and staggered), two different Reynold's numbers (1500 and 2000), and different stand-off distances (Z/D) both experimentally and numerically. The Z/D considered are 3, 5, and 8. In jet impingement cooling, the jet of fluid strikes perpendicular to the target surface to be cooled with high velocity to dissipate the heat. The target surface is heated up by a direct current (DC) power source. The experimental results are obtained by means of thermal image processing of the captured infra-red (IR) thermal images of the target surface. Computational fluid dynamics (CFD) analysis were employed to predict the complex heat transfer and flow phenomena, primarily the line-averaged and area-averaged Nusselt number and the cross-flow effects. In the current investigation, the flow is confined along with the nozzle plate and two parallel surfaces forming a bi-directional channel (bi-directional exit). The results show a comparison between heat transfer enhancement with in-line and staggered nozzle arrays. It is observed that the peaks of the line-averaged Nusselt number (Nu) become less as the stand-off distance (Z/D) increases. It is also observed that the fluctuations in the stagnation heat transfer are caused by the impingement of the primary vortices originating from the jet nozzle exit.


2021 ◽  
pp. 1-13
Author(s):  
Faisal Shaikh ◽  
Budimir Rosic

Abstract Gas turbine blades and vanes are typically manufactured with small clearances between adjacent vane and blade platforms, termed the midpassage gap. The midpassage gap reduces turbine efficiency and causes additional heat load into the vane platform, as well as changing the distribution of endwall heat transfer and film cooling. This paper presents a low-order analytical analysis to quantify the effects of the midpassage gap on aerodynamics and heat transfer, verified against an experimental campaign and CFD. Using this model, the effects of the gap can be quantified, for a generic turbine stage, based only on geometric features and the passage static pressure field. It is found that at present there are significant losses and a large proportion of heat load caused by the gap, but that with modified design this could be reduced to negligible levels. Cooling flows into the gap to prevent ingression are investigated analytically and with CFD. Recommendations are given for targets that turbine designers should work toward in reducing the adverse effects of the midpassage gap. A method to estimate the effect of gap flow is presented, so that for any machine the significance of the gap may be assessed.


Author(s):  
Yaping Ju ◽  
Yi Feng ◽  
Chuhua Zhang

Abstract Reynolds averaged Navier-Stokes model-based conjugate heat transfer method is popularly used in simulations and designs of internally cooled gas turbine blades. One of the important factors influencing its prediction accuracy is the choice of turbulence models for different fluid regions because the blade passage flow and internal cooling have considerably different flow features. However, most studies adopted the same turbulence models in passage flow and internal cooling. Another important issue is the comprehensive evaluation of the losses caused by flow and heat transfer for both fluid and solid regions. In this study, a RANS-based CHT solver for subsonic/transonic flows was developed based on OpenFOAM and validated and used to explore suitable RANS turbulence model combinations for internally cooled gas turbine blades. Entropy generation, able to weigh the losses caused by flow friction and heat transfer, was used in the analyses of two internally cooled vanes to reveal the loss mechanisms. Findings indicate that the combination of the k-? SST-?-Re? transition model for passage flow and the standard k-e model for internal cooling agreed best with measurement data. The relative error of vane dimensionless temperature was less than 3%. The variations of entropy generation with different internal cooling inlet velocities and temperatures indicate that reducing entropy generation was contradictory with enhancing heat transfer performance. This study, providing a reliable computing tool and a comprehensive performance parameter, has an important application value for the design of internally cooled gas turbine blades.


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