Improvement of a Film-Cooled Blade by Application of the Conjugate Calculation Technique

2005 ◽  
Vol 128 (3) ◽  
pp. 572-578 ◽  
Author(s):  
Karsten Kusterer ◽  
Torsten Hagedorn ◽  
Dieter Bohn ◽  
Takao Sugimoto ◽  
Ryozo Tanaka
Keyword(s):  
Heat Transfer ◽  
Thermal Load ◽  
Numerical Models ◽  
Measurement Data ◽  
Test Configuration ◽  
Blade Cooling ◽  
Calculation Technique ◽  
High Thermal Load ◽  
Calculation Results ◽  
Conjugate Calculation

The conjugate calculation technique has been used for the three-dimensional thermal load prediction of a film-cooled test blade of a modern gas turbine. Thus, it becomes possible to take into account the interaction of internal flows, external flow, and heat transfer without the prescription of heat transfer coefficients. The numerical models consist of all internal flow passages and cooling hole rows, including shaped holes. Based on the results, deficiencies of the test configuration close to the leading edge region and in the blade tip region have been detected, which lead to hot spots and surface areas of high thermal load. These regions of high thermal load have been confirmed by thermal index paint measurements in good agreement to the conjugate calculation results. Based on the experimental and numerical results, recommendations for the improvement of the blade cooling were derived and an improved blade-cooling configuration has been designed. The conjugate calculation results, as well as new measurement data, show that the changes in the cooling design have been successful with respect to cooling performance. Regions of high thermal load have vanished, and effective cooling is reached for all critical parts of the test blade.

Improvement of a Film-Cooled Blade by Application of the Conjugate Calculation Technique

2005 ◽  
Author(s):  
Karsten Kusterer ◽  
Torsten Hagedorn ◽  
Dieter Bohn ◽  
Takao Sugimoto ◽  
Ryozo Tanaka
Keyword(s):  
Heat Transfer ◽  
Thermal Load ◽  
Numerical Models ◽  
Measurement Data ◽  
Test Configuration ◽  
Blade Cooling ◽  
Calculation Technique ◽  
High Thermal Load ◽  
Calculation Results ◽  
Conjugate Calculation

The conjugate calculation technique has been used for the three-dimensional thermal load prediction of a film-cooled test blade of a modern gas turbine. Thus, it becomes possible to take into account the interaction of internal flows, external flow, and heat transfer without the prescription of heat transfer coefficients. The numerical models consist of all internal flow passages and cooling hole rows including shaped holes. Based on the results, deficiencies of the test configuration close to the leading edge region and in the blade tip region have been detected, which lead to hot spots and surface areas of high thermal load. These regions of high thermal load have been confirmed by thermal index paint measurements in good agreement to the conjugate calculation results. Based on the experimental and numerical results, recommendations for the improvement of the blade cooling were derived and an improved blade cooling configuration has been designed. The conjugate calculation results as well as new measurement data show that the changes in the cooling design have been successful with respect to cooling performance. Regions of high thermal load have vanished and effective cooling is reached for all critical parts of the test blade.

Conjugate Calculations for a Film-Cooled Blade Under Different Operating Conditions

2004 ◽  
Author(s):  
Karsten Kusterer ◽  
Dieter Bohn ◽  
Takao Sugimoto ◽  
Ryozo Tanaka
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Thermal Load ◽  
Operating Conditions ◽  
Design Flow ◽  
Gas Turbine Blade ◽  
Calculation Technique ◽  
High Thermal Load ◽  
Conjugate Calculation

Conjugate heat transfer and flow calculation techniques (CCT: Conjugate Calculation Technique) developed by several numerical groups have been applied to more and more complex three-dimensional cooling configurations. With respect to gas turbine blade cooling, conjugate calculation codes are turning out as useful tools for the support of the thermal design process. Thus, the main focus of the present study is to investigate the applicability of the CCT on a realistic film-cooling configuration of a modern gas turbine blade under hot gas operating conditions. Thermal index paint measurements for the investigated configuration have been performed at KHI Gas Turbine R&D Center in order to provide thermal load data for comparison to results of conjugate blade analysis. The comparison shows that with respect to regions with high thermal load a qualitatively good agreement of the conjugate results and the measurements can be found although the calculation models contain several simplifications for the internal cooling configuration particularly. The tip region of the blade trailing edge is exposed to a high thermal load. This result can be found in the measurement data as well as in the numerical analysis. The influence of off-design flow conditions on the film cooling flow at the blade leading edge is also investigated. Despite the model simplification, the Conjugate Calculation Technique turns out to be applicable for the numerical testing of the cooling configuration investigated. With the numerical results, useful information for further improvement of the investigated cooling configuration can be provided.

Analysis of the Influence of Cooling Steam Conditions on the Cooling Efficiency of a Steam-Cooled Vane Using the Conjugate Calculation Technique

2001 ◽  
Author(s):  
Uwe Krüger ◽  
Karsten Kusterer ◽  
Gernot Lang ◽  
Hauke Rösch ◽  
Dieter Bohn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Gas Turbines ◽  
Pressure Level ◽  
Lower Pressure ◽  
Air Cooling ◽  
Cooling Efficiency ◽  
Test Configuration ◽  
Calculation Technique ◽  
Conjugate Calculation

Closed circuit steam cooling of blades and vanes in modern gas turbines is an promising alternative instead of film-cooling using compressor air. The temperature drop across the first-stage nozzle, which is convectively steam-cooled, is reduced significantly in comparison to an intensive film-cooled vane using compressor air. Thus, the firing temperature (temperature in front of the first-stage blade row) can be increased while the combustion temperature can remain as low as necessary for low-Nox purpose. In this paper, a steam-cooled test configuration consisting of a 3-vane cascade is numerically analysed. A computer code using a Conjugate Calculation Technique is applied. The CHTflow code has been developed at the Institute of Steam and Gas Turbines in Aachen. Due to the direct coupling of fluid flow and solid body, heat transfer boundary conditions at the external and internal surfaces become unnecessary. Validation of the code for a similar convection-cooled configuration is also given here. The presented investigations focus on the thermal load analysis and the cooling efficiency analysis of the test configuration. It consists of a planar cascade with a convection-cooled central vane where cooling fluid can be supplied to 22 radial passages. One main aspect of the paper is to show the influence of cooling steam conditions (low-, medium & high-pressure steam supply) on the local and global cooling efficiencies. The results show that, for reaching a defined cooling efficiency level, medium steam pressure supply might be advantageous in comparison to a high-pressure level in supply. Although a lower pressure level demands an increase in steam mass flow, the overall effect on the thermal efficiency of the whole process is acceptable if one keeps in mind the advantages of handling steam at lower pressure levels. For further comparison, convective air-cooling with reasonable cooling conditions and comparable flow and heat transfer characteristics is analysed. For the given geometry of the configuration, sufficient cooling of the trailing edge becomes problematic for steam- and air-cooling application.

Effects of Upstream Step Geometry on Axisymmetric Converging Vane Endwall Secondary Flow and Heat Transfer at Transonic Conditions

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Zhigang Li ◽  
Luxuan Liu ◽  
Jun Li ◽  
Ridge A. Sibold ◽  
Wing F. Ng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Thermal Load ◽  
Numerical Study ◽  
Guide Vane ◽  
Leading Edge ◽  
Step Height ◽  
Temperature History ◽  
Flow And Heat Transfer ◽  
High Thermal Load

This paper presents a detailed experimental and numerical study on the effects of upstream step geometry on the endwall secondary flow and heat transfer in a transonic linear turbine vane passage with axisymmetric converging endwalls. The upstream step geometry represents the misalignment between the combustor exit and the nozzle guide vane endwall. The experimental measurements were performed in a blowdown wind tunnel with an exit Mach number of 0.85 and an exit Re of 1.5×106. A high freestream turbulence level of 16% was set at the inlet, which represents the typical turbulence conditions in a gas turbine engine. Two upstream step geometries were tested for the same vane profile: a baseline configuration with a gap located 0.88Cx (43.8 mm) upstream of the vane leading edge (upstream step height = 0 mm) and a misaligned configuration with a backward-facing step located just before the gap at 0.88Cx (43.8 mm) upstream of the vane leading edge (step height = 4.45% span). The endwall temperature history was measured using transient infrared thermography, from which the endwall thermal load distribution, namely, Nusselt number, was derived. This paper also presents a comparison with computational fluid dynamics (CFD) predictions performed by solving the steady-state Reynolds-averaged Navier–Stokes with Reynolds stress model using the commercial CFD solver ansysfluent v.15. The CFD simulations were conducted at a range of different upstream step geometries: three forward-facing (upstream step geometries with step heights from −5.25% to 0% span), and five backward-facing, upstream step geometries (step heights from 0% to 6.56% span). These CFD results were used to highlight the link between heat transfer patterns and the secondary flow structures and explain the effects of upstream step geometry. Experimental and numerical results indicate that the backward-facing upstream step geometry will significantly enlarge the high thermal load region and result in an obvious increase (up to 140%) in the heat transfer coefficient (HTC) level, especially for arched regions around the vane leading edge. However, the forward-facing upstream geometry will modestly shrink the high thermal load region and reduce the HTC (by ∼10% to 40% decrease), especially for the suction side regions near the vane leading edge. The aerodynamic loss appears to have a slight increase (0.3–1.3%) because of the forward-facing upstream step geometry but is slightly reduced (by 0.1–0.3%) by the presence of the backward upstream step geometry.

Design of an axially concave pad profile for a large turbine tilting-pad bearing

2016 ◽  
Vol 231 (4) ◽  
pp. 479-488 ◽  
Author(s):  
Sebastian Kukla ◽  
Nico Buchhorn ◽  
Beate Bender
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Load Capacity ◽  
Measurement Data ◽  
Tangential Direction ◽  
Measured Temperature ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Tilting Pad ◽  
Calculation Results

To improve operational safety and/or achieve a higher load capacity of turbine tilting-pad bearings, an axially concave pad profile is presented. The thermal and mechanical stress of the loaded pads of a test bearing in load between pivot configuration has been analysed. Both film thickness and pressure distribution have been measured at a very high resolution. A fluid film calculation program in combination with a finite-volume-based structural mechanics program is used to simulate the deformation of a single pad under high circumferential speeds. In this context, the axial and tangential heat transfer coefficients of the pad surface, which act as boundary conditions for the calculation of the 3D temperature distribution, are determined using an optimization process. Herein, the match of predicted and measured pad temperatures is the goal. It can be shown that there must be a huge difference in heat transfer in axial and tangential direction in order to match the large measured temperature gradient in circumferential direction. Based on the measured deformed profile the program code is used to derive a concave pad profile, which will result in an axially non-arched sliding surface under the expected thermal load. Therefore, an iterative simulation procedure is used. By decreasing the axial arching of the pad and thus the large film thickness at the axial ends using an improved profile designed for a specific operation point, the minimum film thickness and maximum pad temperature can be influenced beneficially. The comparison of measurement data and calculation results shows very good agreement regarding the pad deformations. The results indicate that by axially concave profiling of the loaded pads of a large tilting-pad bearing for a specific operation point, the static characteristics in the form of temperature, film thickness and load capacity can be improved.

Effects of Upstream Step Geometry on Axisymmetric Converging Vane Endwall Secondary Flow and Heat Transfer at Transonic Conditions

2018 ◽  
Author(s):  
Zhigang Li ◽  
Luxuan Liu ◽  
Jun Li ◽  
Ridge A. Sibold ◽  
Wing F. Ng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Secondary Flow ◽  
Thermal Load ◽  
Leading Edge ◽  
Step Height ◽  
Flow And Heat Transfer ◽  
High Thermal Load ◽  
The Heat Transfer Coefficient

This paper presents a detailed experimental and numerical study on the effects of upstream step geometry on the endwall secondary flow and heat transfer in a transonic linear turbine vane passage with axisymmetric converging endwalls. The upstream step geometry represents the misalignment between the combustor exit and the nozzle guide vane endwall. The experimental measurements were performed in a blowdown wind tunnel with an exit Mach number of 0.85 and an exit Re of 1.5 × 106. A high freestream turbulence level of 16% was set at the inlet, which represents the typical turbulence conditions in a gas turbine engine. Two upstream step geometries were tested for the same vane profile: a baseline configuration with a gap located 0.88Cx (43.8 mm) upstream of the vane leading edge (upstream step height = 0 mm) and a misaligned configuration with a backward facing step located just before the gap at 0.88Cx (43.8 mm) upstream of the vane leading edge (step height = 4.45% span). The endwall temperature history was measured using transient infrared thermography, from which the endwall thermal load distribution, namely Nusselt number, were derived. This paper also presents a comparison with CFD predictions performed by solving the steady-state Reynolds Averaged Navier Stokes (RANS) with Reynolds Stress Model using the commercial CFD solver ANSYS Fluent v.15. The CFD simulations were conducted at a range of different upstream step geometries: three forward-facing (upstream step geometries with step heights from −5.25 to 0% span), and five backward-facing, upstream step geometries (step heights from 0 to 6.56% span). These CFD results were used to highlight the link between heat transfer patterns and the secondary flow structures, and explain the effects of upstream step geometry. Experimental and numerical results indicate that the backward-facing upstream step geometry will significantly enlarge the high thermal load region and result in an obvious increase (up to 140%) in the heat transfer coefficient level, especially for arched regions around the vane leading edge. However, the forward-facing upstream geometry will modestly shrink the high thermal load region and reduce the heat transfer coefficient (by ∼10%–40% decrease), especially for the suction side regions near the vane leading edge. The aerodynamic loss appears to have a slight increase (0.3%–1.3%) as a result of the forward-facing upstream step geometry, but is slightly reduced (by 0.1%–0.3%) by the presence of the backward upstream step geometry.

Investigation of Heat Transfer and Flow Characteristics in Fractal Tree-Like Microchannel With Steam Cooling

2017 ◽  
Author(s):  
Linqi Shui ◽  
Bo Huang ◽  
Kunkun Dong ◽  
Chunyan Zhang
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Thermal Load ◽  
Closed Loop ◽  
Low Flow ◽  
Main Body ◽  
Network Systems ◽  
High Thermal Load ◽  
Steam Cooling ◽  
Channel Configuration

Using closed-loop steam to cool blades is beneficial to improve the gas turbine thermal efficiency. Although the steam-cooled blade can provide sufficient cooling for the main body of high temperature blade, the high thermal load is found in the leading and trailing edge. To alleviate the thermal loads as well as thermal stresses, it is necessary to optimize the cooling configuration of closed loop steam-cooled blades. The tree-like branching network systems have the unique high cooling efficiency and low flow resistance as well as even temperature distribution characteristics. Utilizing the efficient transportation branching network as the internal cooling configuration for the steam-cooled blades, is likely to provide useful hits of optimal solution for solving the uneven and insufficient cooling problems at the high thermal load regions. For this purpose, the heat transfer and flow friction features of coolant flow in the tree-like branching microchannel is studied experimentally and numerically. The results indicate that, influenced by the branch effects, the fractal tree-like microchannel provides a desirable low friction factor for the turbulent flow, and an expected better heat transfer performance under the conditions of a higher Re number and larger heat flux. In addition, compared the wall temperature distributions between the fractal tree-like microchannel and serpentine channels with different coolant, adopting the tree-like branching channel configuration combination with steam cooling could provide an excellent even cooling performance for the high temperature metal wall.

scholarly journals Effects of Blade Fillet Structures on Flow Field and Surface Heat Transfer in a Large Meridional Expansion Turbine

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3035
Author(s):  
Fusheng Meng ◽  
Qun Zheng ◽  
Jian Zhang
Keyword(s):  
Heat Transfer ◽  
Turbulent Flows ◽  
Thermal Load ◽  
Three Dimensional ◽  
Leading Edge ◽  
Flow State ◽  
Aerodynamic Loss ◽  
Expansion Turbine ◽  
Large Expansion ◽  
High Thermal Load

This paper is a continuation of the previous work, aiming to explore the influence of fillet configurations on flow and heat transfer in a large meridional expansion turbine. The endwall of large meridional expansion turbine stator has a large expansion angle, which leads to early separation of the endwall boundary layer, resulting in excessive aerodynamic loss and local thermal load. In order to improve the flow state and reduce the local high thermal load, five typical fillet distribution rules are designed. The three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solver for viscous turbulent flows was used to investigate the different fillet configurations of the second stage stator blades of a 1.5-stage turbine, and which fillet distribution is suitable for large meridional expansion turbines. The influence of fillet structures on the vortex system and loss characteristics was analyzed, and its impact on wall thermal load was studied in detail. The fillet structure mainly affects the formation of horseshoe vortexes at the leading edge of the blade so as to reduce the loss caused by horseshoe vortexes and passage vortexes. The fillet structure suitable for the large meridional expansion turbine was obtained through the research. Reasonable fillet structure distribution can not only improve the flow state but also reduce the high thermal load on the wall surface of the meridional expansion turbine. It has a positive engineering guiding value.

Analysis of Overall Heat Transfer Coefficient of Composite Panels for Thermal Insulation

2017 ◽  
Vol 864 ◽  
pp. 179-183
Author(s):  
Tamba Jamiru ◽  
Oludaisi Adekomaya ◽  
Rotimi Sadiku ◽  
Zhongie Huan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Fiber Orientation ◽  
Thermal Load ◽  
Cold Chain ◽  
Composite Panel ◽  
Food Industries ◽  
Overall Heat Transfer Coefficient ◽  
High Thermal Load

Heat infiltration through the external wall of refrigerated vehicles has been a concern to food industries considering high thermal load required to sustain unbroken cold chain. In this research, experiments were carried out with known fibres contents laid out at various orientations and the effect on the heat transfer measured. The results indicate that the estimated overall heat transfer coefficient of the composite reinforced with 10%wt. of fibre at 0o orientation (G10E) offers the lowest U value of 0.386950 W/m2K and 0.196680 W/m2K for 50 mm and 100 mm insulation thicknesses respectively. The effect of fiber orientation in the composite panel in energy saving was to a large extent minimal when compared to the un-oriented composite panel

Numerical Simulation of Solidification Process for a Machine Tool Bed

2011 ◽  
Vol 675-677 ◽  
pp. 987-990
Author(s):  
Ling Tang ◽  
Xu Dong Wang ◽  
Hai Jing Zhao ◽  
Man Yao
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Machine Tool ◽  
Computation Time ◽  
Solidification Process ◽  
Field Calculation ◽  
Original Design ◽  
Calculation Results ◽  
Improved Design

In this paper, the flow, heat transfer and stress during solidification process of the machine tool bed weighed about 2.5ton that has been optimized by structural topologymethod, was calculated with ProCAST software, and the causes of the crack forming in the casting of the machine tool bed was analysed. According to the calculation results, the structural design of the local part where cracks tends to form has been improved, and the heat transfer and the stress are calculated again. By comparing the temperature field with filling of molten cast iron and without filling, it has been found that there was little effect of filling on the results of temperature distribution of the cast, therefore the effect of filling can be ignored in the following temperature field calculation to save computation time. The model has been simplified in the stress field calculation with considering the complexity of the machine tool bed and the cost of computation. Then, the merits and demerits of the original design and the improved design are compared and analyzed depending on the calculated temperature and stress results. It is suggested that the improved one could get a more uniform temperature distribution and then the trend of the crack occurring can be greatly reduced. These results could provide a guide for the actual casting production, achieving the scientific control of the production of castings, ensuring the quality of the castings.

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