Multidisciplinary Optimization of Airfoil Cooling Structure

2008 ◽  
Author(s):  
Grzegorz Nowak
Keyword(s):  
Cooling System ◽  
Computational Cost ◽  
System Optimization ◽  
Multidisciplinary Optimization ◽  
Internal Cooling ◽  
Technical Problems ◽  
Thermal Boundary Conditions ◽  
Optimization Task ◽  
External Conditions ◽  
Cooling Air

This paper discusses the problem of cooling system optimization within a gas turbine airfoil regarding to thermo-mechanical behavior of the component, as well as some economical aspects of turbine operation. The main goal of this paper is to show the possibilities of evolutionary approach application to the cooling system optimization. This method, despite its relatively high computational cost, seems to be a valuable tool to such technical problems. The analysis involves the optimization of location and size of internal cooling passages within an airfoil. Initially cooling is provided with circular passages and heat is transported by convection. During the optimization the number of channels can vary. The task is approached in 3D configuration. Each passage is fed with cooling air of constant parameters at the inlet. Also a constant pressure drop is assumed along the passage length. The thermal boundary conditions in passages vary with diameter and local vane temperature (passage wall temperature). The analysis is performed by means of the genetic algorithm for the optimization task and FEM for the heat transfer predictions within the component. In the present study the airfoil profile is taken as aerodynamically optimal and the objective of the search procedure is to find cooling structure variant that at given external conditions provides lower stresses, material temperature and indirectly coolant usage.

Thermo Mechanical Optimization of Cooled Turbine Vane

2007 ◽  
Author(s):  
Grzegorz Nowak ◽  
Włodzimierz Wro´blewski
Keyword(s):  
Cooling System ◽  
System Optimization ◽  
Internal Cooling ◽  
Thermal Boundary Conditions ◽  
Optimization Task ◽  
Turbine Vane ◽  
External Conditions ◽  
Mechanical Optimization ◽  
Cooling Air ◽  
Material Temperature

This paper discuses the problem of cooling system optimization within a gas turbine vane regarding to thermo-mechanical behaviour of the component. The analysis involves the optimization of location and size of internal cooling passages within the vane. Cooling is provided with ten circular passages and heat is transported by convection. The task is approached in 3D configuration. Each passage is fed with cooling air of constant parameters at the inlet. Also a constant pressure drop is assumed along the passage length. The thermal boundary conditions in passages varied with diameter and local vane temperature (passage wall temperature). The analysis is performed by means of the genetic algorithm for the optimization task and FEM for the heat transfer predictions within the component. In the present study the vane profile is taken as aerodynamically optimal and the objective of the search procedure is to find cooling structure variant that at given external conditions provides possibly low stresses and material temperature.

Application of Conjugate Heat Transfer for Cooling Optimization of a Turbine Airfoil

2009 ◽  
Author(s):  
Grzegorz Nowak ◽  
Włodzimierz Wro´blewski
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Thermal Field ◽  
Cooling System ◽  
Solid Material ◽  
System Optimization ◽  
Point Of View ◽  
Internal Cooling ◽  
Cooling Channels ◽  
Cooling Air

This paper discusses the problem of airfoil cooling system optimization connected with Conjugate Heat Transfer (CHT) analysis for reliable thermal field prediction within a cooled component. Since the full CHT solution, which involves the main flow, blade material and the coolant flow domains is computationally expensive from the point of view of optimization process, it was decided to reduce the problem by fixing the boundary conditions at the blade surface and solving the task for the interior only (both solid material and coolant). Such assumption, on one hand, makes the problem computationally feasible, and on the other, provides more reliable thermal field prediction than it used to be with the empirical relationships. The analysis involves the optimization of location and size of internal cooling passages within an airfoil. Initially, cooling is provided with circular passages and heat is transported by convection. The task is approached in 3D configuration. Each passage is fed with cooling air of constant parameters at the inlet. In the present study the airfoil profile is taken as aerodynamically optimal. The optimization is done with an evolutionary algorithm within a 30 dimensional design space, composed of space coordinates and radii of cooling channels. The search is realized with a weighted single objective function, which consisted of three objectives formulated on the basis of the airfoil’s thermal field and coolant mass flow.

Alstom GT11N2 M Expansion Turbine Design Modification and Operation Experience

2009 ◽  
Author(s):  
Sergey Vorontsov ◽  
Stefan Irmisch ◽  
Alexey Karelin ◽  
Marcelo Rocha
Keyword(s):  
Gas Turbines ◽  
Cooling System ◽  
Engine Performance ◽  
System Optimization ◽  
Interval Length ◽  
Gas Temperature ◽  
Design Modification ◽  
Expansion Turbine ◽  
Efficiency Increase ◽  
Cooling Air

This paper summarizes the development steps and measures taken for the upgrade of the GT11N2 Turbine. The main targets to be achieved were specified as follows: - GT power increase; - GT gross efficiency increase; - Flexible operation with respect to power output and service interval length. All 4 turbine stages were re-designed in order to optimize their aerodynamic performance and minimize cooling air consumption. Turbine aerodynamic efficiency improvement was achieved by means of: - Turbine stage-to-stage loading optimization; - 3D airfoil profiling; - Replacement of the damping bolt of blade 4 by a full shroud; - Stator/rotor sealing optimization. On top of that, cooling air consumption was reduced by means of cooling system optimization for Vane 1, Blade 1, Vane 2, Blade2 and SHS/A. This allowed an increase of TIT (inlet turbine mixed temperature) keeping the hot gas temperature at the turbine inlet unchanged, which is important for meeting lifetime and emission targets. One of the key requirements for this Turbine Upgrade was to use exclusively validated design approaches and design features as available from existing and proven Alstom Gas Turbines ([1], [2], [3]) in order to minimize development- and implementation risks. Manufacturing of the new turbine parts was completed in an exceptionally short time, thanks to a dedicated R&D Logistic and Manufacturing support/process, an efficient NCR (Non Conformance Report) process, early supplier involvement and a very close/open work with suppliers. The first prototype of this turbine was implemented in a GT11N2 customer engine. Performance validation runs, performed in May 2008 confirmed that the design targets for power and efficiency were fully met. The validation of the turbine parts lifetime is still ongoing.

Effusion Cooling System Optimization for Modern Lean Burn Combustor

2016 ◽  
Author(s):  
Antonio Andreini ◽  
Riccardo Becchi ◽  
Bruno Facchini ◽  
Lorenzo Mazzei ◽  
Alessio Picchi ◽  
...  
Keyword(s):  
Film Cooling ◽  
Cooling System ◽  
Heat Removal ◽  
System Optimization ◽  
Field Investigation ◽  
Metal Temperature ◽  
Back Side ◽  
Lean Burn ◽  
Standard Configuration ◽  
Cooling Air

Stricter legislation limits concerning NOx emissions are leading main aero-engine manufacturers to update the architecture of the combustors towards the implementation of lean burn combustion concept. Cooling air availability for the thermal management of combustor liners is significantly reduced, demanding even more effective liner cooling schemes. The state-of-the-art of liner cooling technology is represented by effusion cooling, consisting in a very efficient cooling strategy based on multi-perforated liners, where metal temperature is lowered by the combined protective effect of coolant film and heat removal inside the holes. The present research study aims at deepening the knowledge of effusion systems, exploiting the results of a thorough experimental campaign carried out in two different planar test rigs, equipped with a complete liner cooling scheme composed by slot injection and effusion array. The film cooling protection was analysed using PSP (Pressure Sensitive Paint) technique, while the effect of cooling injection and extraction from the annulus on heat transfer distribution were studied by means of TLC (Thermochromic Liquid Crystals) thermography. Thermal measurements were supported by flow field investigation with standard 2D PIV (Particle Image Velocimetry) in order to highlight the typical velocity distributions generated by a realistic lean injector. These detailed experimental data were exploited in a 1D thermal flow-network solver that allows to better assess the main cooling mechanisms characterising the proposed cooling system. Moreover, an optimized cooling configuration with enhanced back-side convective cooling was proposed and compared with the standard configuration in terms of metal temperature and cooling consumption.

In-Hole Characteristic Interface and Film Cooling Interface Model

2021 ◽  
pp. 1-43
Author(s):  
Zhen Zhang ◽  
Hui Li ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
Theoretical Analysis ◽  
Prediction Model ◽  
Film Cooling ◽  
Source Term ◽  
Stokes Equations ◽  
Cooling System ◽  
Computational Cost ◽  
Operating Conditions ◽  
Internal Cooling ◽  
Interesting Phenomenon

Abstract The performance of film cooling is influenced by many parameters, and the non-uniform flow caused by the internal cooling system is found to largely affect the film cooling, which further complicates the in-hole flow and draws new difficulties in predicting the cooling performance. In this work, we find a very interesting phenomenon that there always exists an in-hole interface, on which distributions of many parameters, including the velocity and kinetic energy, are seldom affected by the mainstream. The existence of this specific interface can be observed for both cylindrical and shaped film holes under most operating conditions. Theoretical analysis of this interface is conducted in this work based on the characteristic decomposition of Navier-Stokes equations and this interface is named as the characteristic interface. Theoretical analysis and numerical observations suggest the film cooling system can be simplified to two weakly coupled regions separated by this interface. It also explains why existing source-term models for film cooling may fail. Based on these findings, a new prediction model is developed, which uses the Convolutional Neural Networks (CNN) to predict boundary conditions on the characteristic interface. The new model outperforms existing source-term models and yields similar accuracy as full-mesh CFD, while reducing computational cost by one order of magnitude. This model is further evaluated in LES, showing moderate success. To sum up, current work reports the characteristic interface phenomenon in film cooling holes, based on which a new and efficient prediction model is developed and verified.

scholarly journals Turbine Blade Cooling System Optimization

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Julian Girardeau ◽  
Jérôme Pailhes ◽  
Patrick Sebastian ◽  
Frédéric Pardo ◽  
Jean-Pierre Nadeau
Keyword(s):  
Gas Turbine ◽  
High Performance ◽  
Cooling System ◽  
System Optimization ◽  
Internal Cooling ◽  
Cooling Systems ◽  
Turbine Blade Cooling ◽  
Turbine Vanes ◽  
Low Efficiency ◽  
Aerodynamic Losses

Designing high performance cooling systems suitable for preserving the service lifetime of nozzle guide vanes of turboshaft engines leads to significant aerodynamic losses. These losses jeopardize the performance of the whole engine. In the same time, a low efficiency cooling system may affect the costs of maintenance repair and overhaul of the engine as component life decreases. Consequently, designing cooling systems of gas turbine vanes is related to a multiobjective design problem. In this paper, it is addressed by investigating the functioning of a blade and optimizing its design by means of an evolutionary algorithm. Systematic 3D CFD simulations are performed to solve the aero-thermal problem. Then, the initial multiobjective problem is solved by aggregating the multiple design objectives into one single relevant and balanced mono-objective function; two different types of mono-objective functions are proposed and compared. This paper also proposes to enhance available knowledge in the literature of cooling systems of gas turbine vanes by simulating the internal cooling system of the vane. From simulations thermal efficiency and aerodynamic losses are compared and their respective influences on the global performances of the whole engine are investigated. Finally, several optimal designs are proposed.

Convective Cooling Optimization of a Blade for a Supercritical Steam Turbine

2011 ◽  
Author(s):  
Grzegorz Nowak ◽  
Włodzimierz Wro´blewski ◽  
Iwona Nowak
Keyword(s):  
Conjugate Heat Transfer ◽  
Thermal Field ◽  
Cooling System ◽  
Solid Material ◽  
System Optimization ◽  
Point Of View ◽  
Search Problem ◽  
Internal Cooling ◽  
Empirical Relationships ◽  
Blade Cooling

This paper discusses the problem of blade cooling system optimization connected with Conjugate Heat Transfer (CHT) analysis for reliable thermal field prediction within a steam cooled component. Since the full CHT solution, which involves the main flow, blade material and the coolant flow domains is computationally expensive from the point of view of optimization process, it was decided to reduce the problem by fixing the boundary conditions at the blade surface and solving the task for the interior only (both solid material and coolant). Such assumption, on one hand, makes the problem computationally feasible, and on the other, provides more reliable thermal field prediction than it used to be with the empirical relationships. The analysis involves shape optimization of internal cooling passages within an airfoil. The cooling passages are modeled with a set of four Bezier splines joined together to compose a closed contour. Each passage is fed with cooling steam of constant parameters at the inlet. In the present study the airfoil profile is taken as aerodynamically optimal. The search problem is solved with evolutionary algorithm and the final configuration is to be found among the Pareto optimal cooling candidates.

Siemens SGT-800 Industrial Gas Turbine Enhanced to 50MW: Combustor Design Modifications, Validation and Operation Experience

2013 ◽  
Author(s):  
Daniel Lörstad ◽  
Annika Lindholm ◽  
Jan Pettersson ◽  
Mats Björkman ◽  
Ingvar Hultmark
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Cooling System ◽  
Good Condition ◽  
Combined Cycle ◽  
Combustion Stability ◽  
Combustion System ◽  
Design Work ◽  
Engine Operation ◽  
Cooling Air

Siemens Oil & Gas introduced an enhanced SGT-800 gas turbine during 2010. The new power rating is 50.5MW at a 38.3% electrical efficiency in simple cycle (ISO) and best in class combined-cycle performance of more than 55%, for improved fuel flexibility at low emissions. The updated components in the gas turbine are interchangeable from the existing 47MW rating. The increased power and improved efficiency are mainly obtained by improved compressor airfoil profiles and improved turbine aerodynamics and cooling air layout. The current paper is focused on the design modifications of the combustor parts and the combustion validation and operation experience. The serial cooling system of the annular combustion chamber is improved using aerodynamically shaped liner cooling air inlet and reduced liner rib height to minimize the pressure drop and optimize the cooling layout to improve the life due to engine operation hours. The cold parts of the combustion chamber were redesigned using cast cooling struts where the variable thickness was optimized to maximize the cycle life. Due to fewer thicker vanes of the turbine stage #1, the combustor-turbine interface is accordingly updated to maintain the life requirements due to the upstream effect of the stronger pressure gradient. Minor burner tuning is used which in combination with the previously introduced combustor passive damping results in low emissions for >50% load, which is insensitive to ambient conditions. The combustion system has shown excellent combustion stability properties, such as to rapid load changes and large flame temperature range at high loads, which leads to the possibility of single digit Dry Low Emission (DLE) NOx. The combustion system has also shown insensitivity to fuels of large content of hydrogen, different hydrocarbons, inerts and CO. Also DLE liquid operation shows low emissions for 50–100% load. The first SGT-800 with 50.5MW rating was successfully tested during the Spring 2010 and the expected performance figures were confirmed. The fleet leader has, up to January 2013, accumulated >16000 Equivalent Operation Hours (EOH) and a planned follow up inspection made after 10000 EOH by boroscope of the hot section showed that the combustor was in good condition. This paper presents some details of the design work carried out during the development of the combustor design enhancement and the combustion operation experience from the first units.

Combined Experimental and CFD Study of a HP Blade Multi-Pass Cooling System

2009 ◽  
Author(s):  
D. Jackson ◽  
P. Ireland ◽  
B. Cheong
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Detailed Comparison ◽  
Bulk Temperature ◽  
Internal Cooling ◽  
3 Dimensional ◽  
Turbine Cooling ◽  
Cooling Hole ◽  
The Difference

Progress in the computing power available for CFD predictions now means that full geometry, 3 dimensional predictions are now routinely used in internal cooling system design. This paper reports recent work at Rolls-Royce which has compared the flow and htc predictions in a modern HP turbine cooling system to experiments. The triple pass cooling system includes film cooling vents and inclined ribs. The high resolution heat transfer experiments show that different cooling performance features are predicted with different levels of fidelity by the CFD. The research also revealed the sensitivity of the prediction to accurate modelling of the film cooling hole discharge coefficients and a detailed comparison of the authors’ computer predictions to data available in the literature is reported. Mixed bulk temperature is frequently used in the determination of heat transfer coefficient from experimental data. The current CFD data is used to compare the mixed bulk temperature to the duct centreline temperature. The latter is measured experimentally and the effect of the difference between mixed bulk and centreline temperature is considered in detail.

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