Novel Focal Sweep Strategy for Optical Aerothermal Measurements of Film-Cooled Gas Turbine Blades With Highly Inclined Viewing Angle

2021 ◽  
Vol 144 (3) ◽  
Author(s):  
Hongyi Shao ◽  
Xu Zhang ◽  
Di Peng ◽  
Yingzheng Liu ◽  
Wenwu Zhou ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Flat Plate ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Turbine Blades ◽  
Viewing Angle ◽  
Sweep Method ◽  
Gas Turbine Blades ◽  
3D Point Clouds

Abstract The viewing angle for optical aerothermal measurements on turbine surfaces is often limited by the turbine structure, requiring the optical system to have a large depth of field (DoF). Although the DoF can be increased by decreasing the lens aperture, this approach is impractical as a large aperture is essential to maintain an acceptable signal-to-noise ratio (SNR). To solve these problems in the optical aerothermal measurements of film-cooled gas turbine blades, an approach combining the focal-sweep method and three-dimensional (3D) reconstruction is proposed. The focal-sweep method is used to obtain all-in-focus images at an inclined viewing angle, following which the two-dimensional image is restored through 3D reconstruction. Thus, 3D point clouds with both a large DoF and high SNR can be produced. The developed method was validated via flat-plate film cooling experiments using pressure-sensitive paint at three blowing ratios of 0.4, 0.8, and 1.2, as well as three viewing angles. The measured adiabatic effectiveness contours demonstrate that the proposed method can produce all-in-focus measurements at highly inclined viewing angles, albeit at the price of slightly higher noise. In flat-plate experiments, the maximum relative difference is measured to be 6% between results obtained by conventional method at normal view and the proposed method at highly inclined view. Furthermore, the proposed method was applied to the turbine blade cascade film cooling experiment at a highly inclined viewing angle, and successfully reconstructed the 3D point cloud of the cooling effectiveness at the curved turbine blade surface.

scholarly journals Experience in Extending the Life of Gas Turbine Blades

1980 ◽  
Author(s):  
J. Liburdi ◽  
J. O. Stephens
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Hot Isostatic Pressing ◽  
Creep Damage ◽  
Complete Recovery ◽  
Gas Turbine Blades ◽  
Reheat Treatment ◽  
Service Exposure ◽  
Prolonged Service

This paper presents the effects of deterioration of gas turbine blade life with prolonged service exposure. This deterioration is primarily due to internal microstructural changes and the formation of creep voids or cavitation. Methods of evaluating residual blade life or life trend curves are presented along with a documentation of the creep damage observed. The extension of blade life by Hot isostatic pressing versus reheat treatment is discussed and data is presented to show that complete recovery of properties can be achieved even after the material has suffered extensive internal creep damage. As a result, the time between overhauls for blades can be significantly extended, and the need for replacement blades can be minimized.

scholarly journals Coal Mineral Matter Transformation During Combustion and its Implications for Gas Turbine Blade Erosion

1990 ◽  
Author(s):  
S. Rajan ◽  
J. K. Raghavan
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Coal Dust ◽  
Turbine Blades ◽  
Mineral Matter ◽  
One Dimensional ◽  
Gas Turbine Blades ◽  
Edx Analysis ◽  
Ft Ir

The transformation of mineral matter during combustion and the characteristics of the ash formed are important from the standpoint of coal fired gas turbine operation. Using a novel FT-IR technique and EDX analysis, these mineral matter transformations are investigated when the coal is burnt in a one-dimensional pulverized coal-dust-air flame. The role of clays, pyrite, quartz, potassium and other compounds in the ash are discussed with particular reference to deposit buildup and erosion of gas turbine blades.

Film Cooling of Gas Turbine Blades: A Study of the Effect of Large Temperature Differences on Film Cooling Effectiveness

1977 ◽  
Vol 99 (1) ◽  
pp. 11-20 ◽  
Author(s):  
M. A. Paradis
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Large Temperature ◽  
Constant Property ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Gas Turbine Blades ◽  
Combustion Gases ◽  
Simple Equations

Experiments have been performed on the film cooling of gas turbine blades in order to study the influence of large temperature differences on the effectiveness of film cooling. A two-dimensional flat plate model was tested in a stream of 1000 K combustion gases flowing at between 110 and 170 m/s. The model was cooled on both sides by jets of air coming from flush angled slots. The range of velocity ratios Uc/Ug covered was from 0.3 to 1.7 and the range of blowing rates was between 0.5 and 5. Film cooling effectiveness was measured and boundary layer traverses were performed. It has been found that once radiation and conduction effects are taken into account, the simple equations proposed by previous workers for the constant property case could be used with little error.

AERODYNAMICS AND HEAT TRANSFER INSIDE A GAS TURBINE MID-PASSAGE GAP

2021 ◽  
pp. 1-13
Author(s):  
Faisal Shaikh ◽  
Budimir Rosic
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Film Cooling ◽  
Heat Load ◽  
Turbine Blades ◽  
Turbine Stage ◽  
Gas Turbine Blades ◽  
Cooling Flows ◽  
Turbine Efficiency ◽  
Gap Flow

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.

scholarly journals Theoretical Analysis of Gas Turbine Blades by Finite Element Method

1970 ◽  
Vol 8 (1-2) ◽  
pp. 1-11
Author(s):  
B. Deepanraj ◽  
P. Lawrence
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Optimum Number ◽  
Element Analysis ◽  
Gas Turbine Blades ◽  
Functional Part

Gas turbine is an important functional part of many applications. Cooling of blades has been a major concern since they are in a high temperature environment. Various techniques have been proposed for the cooling of blades and one such technique is to have axial holes along the blade span. Finite element analysis is used to analyze thermal and structural performance due to the loading condition, with material properties of Titanium- Aluminum Alloy. Six different models with different number of holes (7, 8, 9, 10, 11, 12) where analyzed in this paper to find out the optimum number of holes for good performance. In Finite element analysis, first thermal analysis followed by structural analysis is carried out. Graphs plotted for temperature distribution for existing design (12 holes) and for 8 holes against time. 2D and 3D model of the blade with cooling passages are shown. Using ANSYS, bending stress, deflection, temperature distribution for number of holes are analyzed. Results have been discussed and we found that when the numbers of holes are increased in the blade, the temperature distribution falls down. For the blade configuration with 8 holes, the temperature near to the required value i.e., 800oC is obtained. Thus a turbine blade with 8 holes configuration is found to be the optimum solution.Keywords: Gas turbine blade; Stress; Deflection; Temperature distributionDOI: http://dx.doi.org/10.3126/jie.v8i1-2.5092Journal of the Institute of Engineering Vol. 8, No. 1&2, 2010/2011Page : 1-11Uploaded Date: 19 July, 2011

Efficient structural analysis of gas turbine blades

2018 ◽  
Vol 90 (9) ◽  
pp. 1305-1316
Author(s):  
Timo Rogge ◽  
Ricarda Berger ◽  
Linus Pohle ◽  
Raimund Rolfes ◽  
Jörg Wallaschek
Keyword(s):  
Structural Analysis ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Element Model ◽  
Gas Turbine Blade ◽  
Quality Of Results ◽  
Content Type ◽  
Gas Turbine Blades

Purpose The purpose of this study a fast procedure for the structural analysis of gas turbine blades in aircraft engines. In this connection, investigations on the behavior of gas turbine blades concentrate on the analysis and evaluation of starting dynamics and fatigue strength. Besides, the influence of structural mistuning on the vibration characteristics of the single blade is analyzed and discussed. Design/methodology/approach A basic computation cycle is generated from a flight profile to describe the operating history of the gas turbine blade properly. Within an approximation approach for high-frequency vibrations, maximum vibration amplitudes are computed by superposition of stationary frequency responses by means of weighting functions. In addition, a two-way coupling approach determines the influence of structural mistuning on the vibration of a single blade. Fatigue strength of gas turbine blades is analyzed with a semi-analytical approach. The progressive damage analysis is based on MINER’s damage accumulation assuming a quasi-stable behavior of the structure. Findings The application to a gas turbine blade shows the computational capabilities of the approach presented. Structural characteristics are obtained by robust and stable computations using a detailed finite element model considering different load conditions. A high quality of results is realized while reducing the numerical costs significantly. Research limitations/implications The method used for analyzing the starting dynamics is based on the assumption of a quasi-static state. For structures with a sufficiently high stiffness, such as the gas turbine blades in the present work, this procedure is justified. The fatigue damage approach relies on the existence of a quasi-stable cyclic stress condition, which in general occurs for isotropic materials, as is the case for gas turbine blades. Practical implications Owing to the use of efficient analysis methods, a fast evaluation of the gas turbine blade within a stochastic analysis is feasible. Originality/value The fast numerical methods and the use of the full finite element model enable performing a structural analysis of any blade structure with a high quality of results.

High-Pressure Gas Turbine Vane Turbulent Flows and Heat Transfer Predicted by RANS/LES/DES

2017 ◽  
Author(s):  
Ping Dong ◽  
R. S. Amano
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Gas Turbine ◽  
Turbulent Flows ◽  
Film Cooling ◽  
Turbine Blades ◽  
Suction Side ◽  
Gas Turbine Blades ◽  
Flow And Heat Transfer ◽  
Turbine Vane

The lifetime of the modern gas turbines greatly depends on the durability of hot section components operating at high temperatures. Film cooling is key to air cooling technologies in modern gas turbine and widely used in high-temperature and high-pressure blades as an active cooling scheme. The requirements of accurate prediction of aerodynamic flow and heat transfer in gas turbine blades lay the essential foundation of cooling effectiveness improvement and working life estimation. In recent days, Large Eddy Simulations (LES) is considered as a useful tool to predict turbulent flows and heat transfer around gas turbine blades, but, comparing to the Reynolds-Averaged Navier–Stokes (RANS) methods, the LES method usually needs more computing resource and depends on computational power and mesh quality. In this paper, LES/DES (Detached Eddy Simulation) predictions were compared to RANS prediction with interest in the accuracy and improvement of turbulent flow and heat transfer phenomena around NASA’s C3X high-pressure gas turbine vane with leading edge cooling film. RANS/LES/DES were detailed and further investigated to assess their ability to predict flow and heat transfer in boundary layer around C3X vane. The current predictions showed that the mix between film cooling injections and free stream resulted in complex flow and heat transfer in the boundary layer on the external vane surface. The predictions of the aerodynamic load along the C3X vane with RANS/LES/DES were almost identical and agreed well with the experimental results. However, the heat transfer predictions with RANS/LES/DES were different. The transition prediction showed the best agreement with the experiment data in the most region. The LES prediction only partially agreed with the experimental data before separation point on the suction side and mild pressure gradient region on the pressure side. The DES and RANS predictions agreed with the experiment data after separation point on the suction side and most region on the pressure side.

Mechanical Properties According to Heat Treatment for Gas Turbine Blade Material

2007 ◽  
Vol 26-28 ◽  
pp. 209-212
Author(s):  
Moon Young Kim ◽  
Sung Ho Yang ◽  
Kuk Hyun Song
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Hot Isostatic Pressing ◽  
Experimental Result ◽  
Gas Turbine Blade ◽  
Post Heat Treatment ◽  
Gas Turbine Blades

This work was studied for the changes of thermal properties on GTD-111 DS (Directional Solidification) gas turbine blade. In this study, gas turbine blades with 24,000~34,000 firing hours was used to get more effective result, gradually applied hot isostatic pressing (HIP) and post-heat treatment for these samples. In the latter steps, we observed changes of γ´ phase affected in material properties, and microhardness test was carried out to evaluate mechanical properties according to changes of γ´ fraction and shape. Experimental result shows, changes of γ´ fraction and shape were affected by HIP and post-heat treatment. And also mechanical properties changes such as micro-hardness related to γ´ phase. In this study, we explained changing transition of microstructure according to γ´ fraction distribution.

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