• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.427-430
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• 2007

Gas turbine disk components have been used by Ni-base superalloys which have high temperature strength for enduring stress induced by high speed rotation. This study introduced the overview of development strategy of precision forging of turbine disk and closed-die forging process for manufacturing good quality gas turbine disk. To make superior quality turbine disk, it is important to select optimal forging process conditions like preform shape, die shape and forging temperature etc. In this paper, closed-die forging process has been studied through the rigid-plastic finite element simulation. Proposed forging process can be used for the successful manufacturing of small-size gas turbine disk.

• Journal of Astronomy and Space Sciences
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• v.2 no.2
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• pp.153-174
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• 1985

The one of critical factor in gas turbine engine performance is high turbine inlet gas temperature. Therefore, the turbine rotor has so many problems which must be considered such as the turbine blade cooling, thermal stress of turbine disk due to severe temperature gradient, turbine rotor tip clearance, under the high operating temperature. The purpose of this study is to provider the temperature distribution and heat flux in turbine disk which is required to considered premensioned problem by the Finite Difference Method and the Finite Element Methods on the steady state condition. In this study, the optimum aspect ratio of turbine disk was analysed for various heat conductivity of turbine disk material by Finite Difference Method, and the effect of laminating method with high conductivity materials to disk thickness direction by Finite Element Methods in order to cool the disk. The laminating method with high conductivity material on the side of the disk is effective.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.365-373
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• 2002

For gas turbine engines, the safe life methodology has historically been used fur fatigue life management of failure critical engine components. The safe retirement limit is necessarily determined by a conservative life evaluation procedure, thereby many components which have a long residual life are discarded. The objective of this study is to introduce the damage tolerant design concept into the life management for aircraft engine component instead of conservative fatigue life methodology which has been used for both design and maintenance. Crack growth data were collected on a nickel base superalloy which have been subjected to combined static and cyclic loading at elevated temperatures. Stress analysis fur turbine disk was carried out. The program for computing creep-fatigue crack growth was developed. The residual lifes of turbine disk component under various temperatures and conditions using creep-fatigue crack growth data were estimated. As the result of analysis, it was confirmed that retirement fur cause concept was applicable to the evaluation of residual life of retired turbine disk which had been designed based on the conventional fatigue life methodology.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.370-373
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• 2008

Small size gas turbine disk requires good mechanical strength and creep properties at high temperature. In this study, Waspaloy was used as a superalloy to satisfy these specifications. The control of microstructure was needed to satisfy material properties at high temperature. In order to do this, we studied forging conditions and material analysis. Therefore die and preform design conducted so that hot forged gas turbine disk could have a good microstructure. The die and preform shapes are designed with consideration of the predefined hydraulic press capacity and the microstructure of forging product. Also we carried out the hot compression test for Waspaloy in various test conditions. From these results, we obtained the forging conditions as material temperature, die velocity etc. To verify these forging conditions, we conducted FE simulations by means of the DEFORM 2D-HT. In this study, the hot closed die and preform designs were completed to offer high temperature material properties of a small size gas turbine.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2524-2539
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• 1996

A design process and an axisymmetric boundary integral equation method for precise structural analysis of the aircraft gas turbine rotor disk were developed. This axisymmetric boundary integral equation method for stress and steady-state thermal analysis was improved in solution accuracy by appling an implicit technique for Cauchy principal value evaluation, a subelement technique for weak singular integral evaluation and a double exponentical integral technoque for internal point solution near boundary surfaces. Stresses, temperatures, low cycle fatigue lifes and critical speeds for the turbine rotor disk of the thrust 1421 N class turbojet engine were analysed in a pratical calculation model problem.

• Journal of the Korean Society of Industry Convergence
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• v.11 no.1
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• pp.19-26
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• 2008

The gas-liquid mass transfer volumetric coefficients in gas-liquid agitated vessels with wire gauge impellers were measured to be compared with those in vessels with disk turbine and paddle impellers. Also mass transfer volumetric coefficients for disk turbine, paddle impeller and wire gauge impeller in cylindrical agitated vessel was measured over a wide range of Reynolds number from turbulent flow to transition regions. The effect of geometries on $k_La$ is clarified experimentally. Mass transfer volumetric coefficients $k_La$ depends only on the power consumption ($P_{gv}+P_{av}$) per unit volume.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.190-194
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• 2007

The forging process design and microstructure evolution for gas turbine disk of a Waspaloy is investigated in this study. Parameters related to deformation are die and preform geometry, and forging temperature of die and workpiece. Die and preform design are considered to reduce the forging load, and to avoid the forging defects. Blocker and finisher dies for multistage forging are designed and the initial billet geometry is determined. The control of hot forging parameters such as strain, strain rate and temperature also is important because the microstructure change in hot working affects the mechanical properties. The dynamic recrystallization evolution has been studied in the temperature range 900-$1200^{\circ}C$ and strain rate range 0.01-1.0s-1 using hot compression tests. Modeling equations are required represent the flow curve, recrystallized grain size, recrystallized volume fraction by various tests. In this study, we used to thermo-viscoplastic finite element modeling equation of DEFORM-2D to predict the microstructure change evolution during thermo-mechanical processing. The microstructure is updated during the entire thermal and deformation processes in forging.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.379-384
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• 2014

The most critical rotating parts of a gas turbine engine are turbine blades and disc, given that they must operate under severe conditions such as high turbine inlet temperature, high speeds, and high compression ratios. Owing to theses operating conditions and high rotational speed energy, some failures caused by turbine disks and blades are categorized into catastrophic and critical, respectively. To maximize the margin of structural integrity, we aim to optimize the vulnerable area of disc-blade interface region. Then, to check the robustness of the obtained optimized solution, we evaluated structural reliability under uncertainties such as dimensional tolerance and fatigue life variant. The results highlighted the necessity for and limitations of optimization which is one of deterministic methods, and pointed out the requirement for introducing reliability-based design optimization which is one of stochastic methods. Thermal-structural coupled-filed analysis and contact analysis are performed for them.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.831-838
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• 2004

A fluid-solid conjugate solver has been newly developed and applied to an actual engine disk system. Most of the currently available conjugate solvers lack the special thermal modeling for turbomachinery disk system applications. In the present new code, these special models are implemented to expand the applicability of the conjugate method and to reduce the required computational resources. Most of the conjugate analysis work so far are limited to the axisymmetric framework. However, the actual disk system includes several non-axisymmetric components which inevitably affect the local heat transfer phenomena. Also the previous work devoted to this area usually concentrate their efforts on the steady-state thermal field, although the one in the transient condition is more critical to the engine components. This paper presents full 3D conjugate analysis of a single stage high pressure turbine rotor-stator disk system to assess the three-dimensional effects (Fig. 1). The analysis is carried out not only in the steady-state but also in the engine accelerating transient condition. The predicted temperatures shows good agreement with measured data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.447-453
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• 1999

In MHD power generation system, enthalpy of the working gas is convened to electric power directly through expansion in generator channel. It means that electric power can be generated without a moving mechanical linkage such as turbine blades. The principle of MHD generation is based on Faraday'law of induction that eletromotive force(u$\times$B) is generated when the working gas of velocity u flows a channel in which magnetic field of strength(B) exists. In this paper, helium gas seeded with cesium is used as working gas. There are two types of generator in MHD generation; linear type faraday and disk type hall generator. Rogowski coils having the bandwidth of the 100(Hz) ~ 20(kHz) were used for measuring current flowing MHD disk channel. Optimum load resistor value of the MHD generator studied was 2.5[$\Omega$]. Disk type hall generator's generation performance is the main target of this paper, which superiors to linear type Faraday generator in many points. Isentropic efficiency and enthalpy extraction rate of disk type shock tube driven hall generator is discussed here.