Papers by Keyword: Gas Turbine Blade

Abstract: Ni-Cr superalloy has been widely used in turbomachinery equipments. Gas turbine blade made from Ni-Cr superalloys experience the effect of high temperature and stress during service which certainly cause various microstructural changes. It is found that the formation of spheroidal gamma prime (γ') phase replacing the cuboidal γ' phase and also the formation of M₂₃C₆ carbides along the grain boundaries. Numerous previous study has been conducted and reported that the microstructure of the turbine blade are being modified by service. This study involved assessing changes in blade microstructure and microhardness as a function of service time.

Abstract: Failures of turbine blades are one of the most critical problems in power generating industry. Among the different failure mechanisms, resonant vibration of blades has a major role and therefore is the subject of many recent research works. Therefore, in this paper, modal analysis of a first stage blade in ALSTOM gas turbine is investigated and natural frequencies and vibration modes of blade are found in various conditions. For this purpose, a cloud-point model of a gas turbine blade has been created using 3D Laser Digitizer. Then the numerical calculation by finite element method using ANSYS software based on experimental test conditions is utilized and Experimental natural frequencies have been obtained. The results show acceptable agreement between the experimental and FEM results.

Abstract: The development of a new generation of high performance gas turbine engines requires gas turbines to be operated at very high inlet temperatures, which are much higher than the allowable metal temperatures. Consequently, this necessitates the need for advanced cooling techniques. Among the numerous cooling technologies, the film cooling technology has superior advantages and relatively favorable application prospect. The recent research progress of film cooling techniques for gas turbine blade is reviewed and basic principle of film cooling is also illustrated. Progress on rotor blade and stationary blade of film cooling are introduced. Film cooling development of leading-edge was also generalized. Effect of various factor on cooling effectiveness and effect of the shape of the injection holes on plate film cooling are discussed. In addition, with respect to progress of discharge coefficient is presented. In the last, the future development trend and future investigation direction of film cooling are prospected.

Abstract: Gas turbine blade is the key components of generator which using natural gas as the power source. The airflow channel on the gas turbine blade has an important effect on the blade life and the power generation efficiency. Diamond-nickel composite plated grinding needle was usually used for the airflow channel finish. The process of the diamond-nickel composite plated grinding needle was introduced in this paper. Monolayer of the ~60μm diamond was first embedded in 12μm~15μm nickel layer, then followed with 25μm~30μm thicker nickel layer plated to hold the diamond tightly. The results show that, the coating adhesion was affected by the bath pH and the roughness of the needle original surface. The grinding needle manufactured in optimized process was tested with MICROMOT 50/E drill grinder at the speed of 8000rpm, the results showed that, 5-7 holes were drilled on the glass with thickness of 1.5mm; the drilling speed was 1.5mm/min.

Abstract: The method of active thermography is an innovative NDT technology that was developed over the recent years to investigate microstructure condition of machinery components, including components of gas turbines. The essence of the method consists is examination of the thermal response of a material as a function of time to simulation by means of an external heat pulse. When the microstructure contains areas that differ in thermophysical properties, such differences entail alteration of the diffusion velocity. Therefore monitoring of the temperature field that spreads on the surface area of a workpiece that is being cooled down makes it possible to find locations of such different areas. The paper outlines initial results of investigations, carried out with use of the active thermography, how the temperature affects onto thermophysical properties demonstrated by superalloys used for construction of gas turbines. These investigations enabled to find out variations of thermophysical properties of these superalloys as a function of temperature. Eventually they laid down the fundamentals to undertake broader research studies in that domain. The core objective of the studies was to find out the relationships between variations of the thermal impact and corresponding amendments in the response signal received from the investigated material and to detect the correlations that have not yet been defined with sufficient accuracy. The described relationships and liaisons may contribute to development of fundamentals for the new NDT thermographic method suitable to evaluate the overheating status of gas turbine blades.

Abstract: One of the major factors which have important effects in turbine blade designing is temperature distribution and its heat transfer rate. The temperature distribution in blades depends on many factors; one of the most important ones is the geometry of the blades. In this paper by continuing some previous findings about the geometry[1], an optimized blade and a real one are compared from the thermally aspect view. Flow exit angle of the rotor blade and the blade height are two parameters which have direct effect on the heat transfer rate. The presented temperature distribution is solved based on the new flow exit angle of rotor blade. By optimizing the flow exit angle for the first time, the blade height is computed. By solving mathematically and thermodynamically relations and writing a solving code based on the finite volume method, the temperature and the heat transfer rate are computed numerically. These results shows the direct effect of flow exit angle on temperature distribution which can be used for upgrading the turbine efficiency.

Abstract: The premature failure of a blade occurred after a service life of 8127 EOH operation houre. This paper presents the fracture analysis of the first stage blade through fractographic and mechanical analysis. Crack growth mechanisms were evaluated based on the microscopic observations of the fracture surfaces by SEM. The analysis of the different region of the fracture surface shows that crack propagation is mainly related with fatigue mechanism. The crack propagation occurred in the pressure-suction side direction. The dynamic characteristics of the blade were evaluated by FEM in order to identify the cause of blade failure. The result depicts that the second mode of vibration might be excited and the vibratory stresses cause to HCF damage of the blade. Eventully fracture analysis of the blade under the presence of a fatigue crack was analyzed by FRACNC3D software.

Abstract: To investigate the physical cause of premature blade cracking during the acceleration mission test (AMT) in a test cell environment, an in-depth finite element analysis (FEA) of the blade was conducted using a life prediction system. The results obtained showed that the blades had suffered excessive airfoil creep damage, leading to excessive blade lengthening and airfoil untwisting particularly in the trailing edge region. It is predicted that the uneven rubbing action might have contributed to the fatigue crack nucleation and growth process just below the platform in the shank region of the blade under AMT fatigue cycling conditions, and the excessive creep deformation made a significant effect on the overall crack nucleation process.

Abstract: Applied gas turbine blade material(Ni base Super-alloy) for aircraft as principal parts material of existing electricity generating gas turbine blade. Studied microstructure change after do heat treatment, Hot Isostatic Press(HIP) processing to nickel-based super-alloy. Emphasize in properties of matter refreshing effect confirmation by HIP processing, microstructure observed by scanning electron microscope. HIP processing effect caused positive effect in high temperature Creep and low cycle fatigue failure by microscopic air hole exclusion. Sheep of Eutectic region decreased solid solution being done B, and also precipitated size of cuboidal shape great. Heat treatment effect was seen modification by M23C6 carbide creation that Script MC carbide is microscopic and does Discrete through solution treatment in high temperature state. Precipitation that grow after HIP processing over solution processing and aging processing in heat treatment process solid solution after is done again precipitate being done size decrescent.

Abstract: Combustion gas of gas turbine is about 1100 ~ 1300 °C. Is doing TBC(Thermal Barrier Coating) on the base metal surface to protect rotor or blade from high temperature flame. TBC system reduced heat transfer as metal base metal. TBC system is divided by bond coating of prevent oxidation and corrosion and Top coating reduced of heat transfer by high Temperature flame. The objective of this study was to development of an advance TBC system for high Temperature (>1350°C) gas turbine components. Used coating powder developed newly in coating process, and more than 1350°C by parameter control in usable coating method develop. Internal studies looked at the effect of TBC coating thickness, material chemistry, substrate composition, surface temperature and bond coat as-sprayed surface profile/particle size on technical performance.