Optimization of Trailing Edge Ejection Mixing Losses: A Theoretical and Experimental Study

1999 ◽  
Vol 121 (1) ◽  
pp. 118-125 ◽  
Author(s):  
M. T. Schobeiri ◽  
K. Pappu
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Mass Flow ◽  
Velocity Ratio ◽  
Turbine Blades ◽  
Ejection Velocity ◽  
Trailing Edge ◽  
Gas Turbine Blades ◽  
Flow Deflection ◽  
Mixing Losses

The aerodynamic effects of trailing edge ejection on mixing losses downstream of cooled gas turbine blades were experimentally investigated and compared with an already existing one-dimensional theory by Schobeiri (1989). The significant parameters determining the mixing losses and, therefore, the efficiency of cooled blades, are the ejection velocity ratio, the cooling mass flow ratio, the temperature ratio, the slot thickness ratio, and the ejection flow angle. To cover a broad range of representative turbine blade geometry and flow deflections, a General Electric power generation gas turbine blade with a high flow deflection and a NASA-turbine blade with intermediate flow deflection and different thickness distributions were experimentally investigated and compared with the existing theory. Comprehensive experimental investigations show that for the ejection velocity ratio μ = 1, the trailing edge ejection reduces the mixing losses downstream of the cooled gas turbine blade to a minimum, which is in agreement with the theory. For the given cooling mass flow ratios that are dictated by the heat transfer requirements, optimum slot thickness to trailing edge thickness ratios are found, which correspond to the minimum mixing loss coefficients. The results allow the turbine aerodynamicist to minimize the mixing losses and to increase the efficiency of cooled gas turbine blades.

scholarly journals Optimization of Trailing Edge Ejection Mixing Losses: A Theoretical and Experimental Study

1997 ◽  
Author(s):  
K. R. Pappu ◽  
M. T. Schobeiri
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Mass Flow ◽  
Velocity Ratio ◽  
Turbine Blades ◽  
Ejection Velocity ◽  
Trailing Edge ◽  
Gas Turbine Blades ◽  
Flow Deflection ◽  
Mixing Losses

The aerodynamic effects of trailing edge ejection on mixing losses downstream of cooled gas turbine blades were experimentally investigated and compared with an already existing one-dimensional theory by Schobeiri (1989). The significant parameters determining the mixing losses and therefore the efficiency of cooled blades are the ejection velocity ratio, the cooling mass flow ratio, the temperature ratio, the slot thickness ratio and the ejection flow angle. To cover a broad range of representative turbine blade geometry and flow deflections, a General Electric power generation gas turbine blade with high flow deflection and a NASA-turbine blade with intermediate flow deflection and different thickness distributions were experimentally investigated and compared with the existing theory. Comprehensive experimental investigations show that for the ejection velocity ratio μ = 1, the trailing edge ejection reduces the mixing losses downstream of the cooled gas turbine blade to a minimum which is in agreement with the theory. For the given cooling mass flow ratios that are dictated by the heat transfer requirements, optimum slot thickness to trailing edge thickness ratios are found, which correspond to the minimum mixing loss coefficients. The results allow the turbine aerodynamicist to minimize the mixing losses and to increase the efficiency of cooled gas turbine blades.

Optimum Trailing Edge Ejection for Cooled Gas Turbine Blades

1989 ◽  
Vol 111 (4) ◽  
pp. 510-514 ◽  
Author(s):  
T. Schobeiri
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Velocity Ratio ◽  
Turbine Blades ◽  
Slot Width ◽  
Width Ratio ◽  
Ejection Velocity ◽  
Trailing Edge ◽  
Gas Turbine Blades ◽  
Mixing Losses

The effect of trailing edge ejection on the flow downstream of a cooled gas turbine blade is investigated. Parameters that affect the mixing losses and therefore the efficiency of cooled blades are the ejection velocity ratio, the cooling mass flow ratio, the slot-width ratio, and the ejection angle. For ejection velocity ratio μ = 1, the trailing edge ejection reduces the mixing losses downstream to the cooled blade. For given cooling mass flow ratios, optimum slot-width/trailing edge ratios are found, which correspond to the minimum mixing loss coefficients.

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.

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.

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.

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 Sistema de información para la caracterización de imágenes de desgaste en álabes de rotor de una turbina de gas

2020 ◽  
pp. 27-34
Author(s):  
Luz Yazmín Villagrán-Villegas ◽  
Miguel Patiño-Ortiz ◽  
Luis Héctor Hernández-Gómez ◽  
Víctor Velázquez-Martínez
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Mechanical Failure ◽  
Total Loss ◽  
Mechanical Equipment ◽  
End User ◽  
Gas Turbine Blades ◽  
The Difference

In Mexico, the end user of gas turbines (PEMEX), in the NRF standard, requests the Goodman and Campbell diagrams for the acquisition of new turbo machinery. However, the requirement of the diagrams is not reported when the turbine is sent for overhaul. In this research article, it is suggested that the end user when carrying out a wear analysis of a turbine blade, know precisely the conditions of a blade in case of total loss of the machine or in conditions in which they send one or several turbine discs to the manufacturer and the conditions that receives after overhaul the discs. Wear and friction are the most adverse factors in reducing the useful life of mechanical equipment. The loss of a relatively small amount of material, in certain critical locations of any mechanical part, can make the difference between the damage and the good functioning of the gas turbine, so this research aims to characterize images of a turbine blade with in order to identify any wear or mechanical failure; analyzing the responses to deterministic and non-deterministic variables, looking for responses that contribute to the early detection of any mechanical failure that prevents the total loss of the gas turbine in operation. To achieve the objectives set out in this research, techniques and tools with a systemic and systematic approach are used, which will allow the characterization and interpretation of images of gas turbine blades.

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