scholarly journals Optimization Design of Lattice Structures in Internal Cooling Channel of Turbine Blade

2021 ◽  
Vol 11 (13) ◽  
pp. 5838
Author(s):  
Liang Xu ◽  
Qingyun Shen ◽  
Qicheng Ruan ◽  
Lei Xi ◽  
Jianmin Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Optimization Design ◽  
Mechanical Performance ◽  
Optimization Problems ◽  
Lattice Structure ◽  
Turbine Blades ◽  
Optimization Method ◽  
Internal Cooling ◽  
Geometric Variables

Recently, the inlet temperatures in gas turbine units have been drastically increased, which extremely affects the lifespan of gas turbine blades. Traditional cooling structures greatly improve the high temperature resistance of the blade; however, these structures scarcely concern both heat transfer and mechanical performances. Lattice structure (LS) can realize these requirements because of its characteristics of light weight, high strength, and porosity. Although the topology of LS is complex, it can be manufactured with the 3D metal printing technology. In this study, an integral optimization method of lattice cooling structure, used at the trailing edge of turbine blades, concerned with heat transfer and mechanical performance, was presented. Firstly, functions between the first-order natural frequency (freq1), elasticity modulus (E), relative density (ρ¯), and Nusselt number (Nu), and the geometric variables of pyramid type LS (PLS) and X-type LS (XLS) were established, and the reliability of these functions was verified. Then, a mathematical optimization model was developed based on these functions which contained two selected optimization problems. Finally, relations among objectives were analyzed; influence law of geometric variables to objectives were discussed, and the accuracy of the optimal LS was proved by experiment and numerical simulation. The optimization results suggest that, compared to the initial LS, Nu increases by 24.1% and ρ¯ decreases by 31% in the optimal LS of the first selected problem, and the Nu increases by 28.8% while freq1 and ρ¯ are almost unchanged in the optimal LS of the second selected problem compared to the initial LS. This study may provide a guidance for functions integration design of lattice cooling structures used at turbine blades based on 3D printing.

scholarly journals Optimization Design of Lattice Structures in Internal Cooling Channel with Variable Aspect Ratio of Gas Turbine Blade

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3954
Author(s):  
Liang Xu ◽  
Qicheng Ruan ◽  
Qingyun Shen ◽  
Lei Xi ◽  
Jianmin Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Optimization Model ◽  
Lattice Structure ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Cooling Channels ◽  
Mechanical Performances ◽  
Type Lattice

Traditional cooling structures in gas turbines greatly improve the high temperature resistance of turbine blades; however, few cooling structures concern both heat transfer and mechanical performances. A lattice structure (LS) can solve this issue because of its advantages of being lightweight and having high porosity and strength. Although the topology of LS is complex, it can be manufactured with metal 3D printing technology in the future. In this study, an integral optimization model concerning both heat transfer and mechanical performances was presented to design the LS cooling channel with a variable aspect ratio in gas turbine blades. Firstly, some internal cooling channels with the thin walls were built up and a simple raw of five LS cores was taken as an insert or a turbulator in these cooling channels. Secondly, relations between geometric variables (height (H), diameter (D) and inclination angle(ω)) and objectives/functions of this research, including the first-order natural frequency (freq1), equivalent elastic modulus (E), relative density (ρ¯) and Nusselt number (Nu), were established for a pyramid-type lattice structure (PLS) and Kagome-type lattice structure (KLS). Finally, the ISIGHT platform was introduced to construct the frame of the integral optimization model. Two selected optimization problems (Op-I and Op-II) were solved based on the third-order response model with an accuracy of more than 0.97, and optimization results were analyzed. The results showed that the change of Nu and freq1 had the highest overall sensitivity Op-I and Op-II, respectively, and the change of D and H had the highest single sensitivity for Nu and freq1, respectively. Compared to the initial LS, the LS of Op-I increased Nu and E by 24.1% and 29.8%, respectively, and decreased ρ¯ by 71%; the LS of Op-II increased Nu and E by 30.8% and 45.2%, respectively, and slightly increased ρ¯; the LS of both Op-I and Op-II decreased freq1 by 27.9% and 19.3%, respectively. These results suggested that the heat transfer, load bearing and lightweight performances of the LS were greatly improved by the optimization model (except for the lightweight performance for the optimal LS of Op-II, which became slightly worse), while it failed to improve vibration performance of the optimal LS.

scholarly journals Oscillator Fin as a Novel Heat Transfer Augmentation Device for Gas Turbine Cooling Applications

1998 ◽  
Author(s):  
Oguz Uzol ◽  
Cengiz Camci
Keyword(s):  
Heat Transfer ◽  
Kinetic Energy ◽  
Gas Turbine ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Internal Cooling ◽  
Pin Fin ◽  
Heat Transfer Augmentation

A new concept for enhanced turbulent transport of heat in internal coolant passages of gas turbine blades is introduced. The new heat transfer augmentation component called “oscillator fin” is based on an unsteady flow system using the interaction of multiple unsteady jets and wakes generated downstream of a fluidic oscillator. Incompressible, unsteady and two dimensional solutions of Reynolds Averaged Navier-Stokes equations are obtained both for an oscillator fin and for an equivalent cylindrical pin fin and the results are compared. Preliminary results show that a significant increase in the turbulent kinetic energy level occur in the wake region of the oscillator fin with respect to the cylinder with similar level of aerodynamic penalty. The new concept does not require additional components or power to sustain its oscillations and its manufacturing is as easy as a conventional pin fin. The present study makes use of an unsteady numerical simulation of mass, momentum, turbulent kinetic energy and dissipation rate conservation equations for flow visualization downstream of the new oscillator fin and an equivalent cylinder. Relative enhancements of turbulent kinetic energy and comparisons of the total pressure field from transient simulations qualitatively suggest that the oscillator fin has excellent potential in enhancing local heat transfer in internal cooling passages without significant aerodynamic penalty.

scholarly journals Calculation of Convective Heat Transfer in Square-Sectioned Gas Turbine Blade Cooling Channels

1998 ◽  
Author(s):  
Arash Saidi ◽  
Bengt Sundén
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Cross Sections ◽  
Turbine Blades ◽  
Solution Procedure ◽  
Navier Stokes ◽  
Internal Cooling ◽  
Turbine Blade Cooling ◽  
Cooling Channels ◽  
Energy Equations

Internal cooling channels are commonly used to reduce the thermal loads on the gas turbine blades to improve overall efficiency. In this study a numerical investigation has been carried out to provide a validated and consistent method to deal with the prediction of the fluid flow and the heat transfer of such channels with square cross sections. The rotation modified Navier-Stokes and energy equations together with a low-Re number version of the k-ε turbulence model are solved with appropriate boundary conditions. The solution procedure is based on a numerical method using a collocated grid, and the pressure-velocity coupling is handled by the SIMPLEC algorithm. The computations are performed with the assumption of fully developed periodic conditions. The calculations are carried out for smooth ducts with and without rotation and effects of rotation on the heat transfer are described. Similar numerical calculations have carried out for channels with rib-roughened walls. The obtained results are compared with available experimental data and empirical correlations for the heat transfer rate and the friction factor. Some details of the flow and heat transfer fields are also presented.

Topology Optimization of Serpentine Channels for Minimization of Pressure Loss and Maximization of Heat Transfer Performance As Applied for Additive Manufacturing

2019 ◽  
Author(s):  
Shinjan Ghosh ◽  
Jayanta S. Kapat
Keyword(s):  
Heat Transfer ◽  
Topology Optimization ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Cooling Channels ◽  
Blade Cooling

Abstract Gas Turbine blade cooling is an important topic of research, as a high turbine inlet temperature (TIT) essentially means an increase in efficiency of gas turbine cycles. Internal cooling channels in gas turbine blades are key to the cooling and prevention of thermal failure of the material. Serpentine channels are a common feature in internal blade cooling. Optimization methods are often employed in the design of blade internal cooling channels to improve heat-transfer and reduce pressure drop. Topology optimization uses a variable porosity approach to manipulate flow geometries by adding or removing material. Such a method has been employed in the current work to modify the geometric configuration of a serpentine channel to improve total heat transferred and reduce the pressure drop. An in-house OpenFOAM solver has been used to create non-traditional geometries from two generic designs. Geometry-1 is a 2-D serpentine passage with an inlet and 4 bleeding holes as outlets for ejection into the trailing edge. Geometry-2 is a 3-D serpentine passage with an aspect ratio of 3:1 and consists of two 180-degree bends. The inlet velocity for both the geometries was used as 20 m/s. The governing equations employ a “Brinkman porosity parameter” to account for the porous cells in the flow domain. Results have shown a change in shape of the channel walls to enhance heat-transfer in the passage. Additive manufacturing can be employed to make such unconventional shapes.

Experimental and Numerical Study of Jet Impingement Cooling for Improved Gas Turbine Blade Internal Cooling With In-Line and Staggered Nozzle Arrays

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Abdel Rahman Salem ◽  
Farah Nazifa Nourin ◽  
Mohammed Abousabae ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Gas Turbine ◽  
Numerical Study ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Target Surface ◽  
Internal Cooling ◽  
Impingement Cooling ◽  
Gas Turbine Blades

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.

Experimental and Numerical Analysis of Gas Turbine Blades With Different Internal Cooling Geometries

2009 ◽  
Author(s):  
M. Eifel ◽  
V. Caspary ◽  
H. Ho¨nen ◽  
P. Jeschke
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Base Flow ◽  
Internal Cooling ◽  
Turbine Rotor Blade ◽  
Flow Phenomena ◽  
Sst Turbulence Model

This paper presents the effects of major geometrical modifications to the interior of a convection cooled gas turbine rotor blade. The analysis of the flow is performed experimentally with flow visualization via paint injection into water whereas the flow and the heat transfer are investigated numerically with Ansys CFX utilizing the SST turbulence model. Two sets of calculations are carried out, one under the same conditions as the experiments and another according to realistic hot gas conditions with conjugate heat transfer. The aim is to identify flow phenomena altering the heat transfer in the blade and to manipulate them in order to reduce the thermal load of the material. The operating point of the geometric base configuration is set to Re = 50,000 at the inlet while for the modified geometries the pressure ratio is held constant compared to the base. Flow structures and heat transfer conditions are evaluated and are linked to specific geometric features. Among several investigated configurations one could be identified that leads to a cooling effectiveness 15% larger compared to the base.

Conjugate Heat Transfer Simulation and Entropy Generation Analysis of Gas Turbine Blades

2021 ◽  
Author(s):  
Yaping Ju ◽  
Yi Feng ◽  
Chuhua Zhang
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Entropy Generation ◽  
Conjugate Heat Transfer ◽  
Turbine Blades ◽  
Measurement Data ◽  
Turbulence Models ◽  
Internal Cooling ◽  
Gas Turbine Blades ◽  
Internally Cooled

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.

Experimental and Numerical Analysis of Gas Turbine Blades With Different Internal Cooling Geometries

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
M. Eifel ◽  
V. Caspary ◽  
H. Hönen ◽  
P. Jeschke
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Base Flow ◽  
Internal Cooling ◽  
Turbine Rotor Blade ◽  
Flow Phenomena ◽  
Sst Turbulence Model

This paper presents the effects of major geometrical modifications to the interior of a convection cooled gas turbine rotor blade. The analysis of the flow is performed experimentally with flow visualization via paint injection into water, whereas the flow and the heat transfer are investigated numerically with ANSYS CFX, utilizing the SST turbulence model. Two sets of calculations are carried out: one under the same conditions as the experiments and another according to realistic hot gas conditions with conjugate heat transfer. The aim is to identify flow phenomena altering the heat transfer in the blade and to manipulate them in order to reduce the thermal load of the material. The operating point of the geometric base configuration is set to Re=50,000 at the inlet while for the modified geometries, the pressure ratio is held constant compared with the base. Flow structures and heat transfer conditions are evaluated and are linked to specific geometric features. Among several investigated configurations one could be identified that leads to a cooling effectiveness 15% larger compared with the base.

Two-Phase Flow Simulation of Mist Film Cooling on Turbine Blades With Conjugate Internal Cooling

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Xianchang Li ◽  
Ting Wang
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Flow Simulation ◽  
Solid Base ◽  
Internal Cooling ◽  
Adiabatic Wall ◽  
Two Phase ◽  
Air Film

Effective cooling of gas turbine combustor liners, combustor transition pieces, turbine vanes (nozzles), and blades (buckets) is a critical task to protect these components from the flue gas at extremely high temperature. Air film cooling has been successfully used to cool these hot sections for the past half century. However, the net benefits from the traditional methods seem to be incremental, but the temperature of working gas is continuously increasing to achieve high thermal efficiency. Therefore, new cooling techniques need to be developed. One of the promising techniques is to enhance film cooling with mist injection. While the previous study reported the effect of mist on the cooling effectiveness with an adiabatic wall, this paper focuses on the effect of mist injection on heat transfer of film cooling with a nonadiabatic flat wall, using the commercial computational fluid dynamics software package FLUENT. Both 2D and 3D cases are considered with a 2D slot and diffusive compound-angle holes. Modeling of the interaction of a droplet with a uniformly cooled wall as well as conjugate heat conduction inside the solid base are conducted. Different mist droplet sizes and mist concentrations are adopted. Conditions both in a gas turbine operating environment (15 atm and 1561 K) and in a laboratory environment (1 atm and 450 K) are considered. Results show that injecting 2–10% mist reduces the heat transfer coefficient and the wall temperature. Especially, mist has the prolonged effect of cooling the region downstream for 15 jet hole diameters, where conventional air film cooling is not effective.

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