• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1780-1786
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• 1995

The main goal of the present study is to establish the techniques and methodolgies of turbine performance test through evaluating the objective turbine test piece, and checking the reliability of the self-developed test facility by performing a series of turbine tests under ambient temperature condition. A high speed coupling, a lubrication system and a test bed of the test facility were modified through a series of preliminary test in order to reduce the vibration and oil leakage. The flowrate control of the test facility and data acquisition were accomplished by using a software called "Labview" The measurement of shaft horse power and control of rotational speed according to the conditions of turbine rotation were performed by a separate system. The preliminary evaluation of the measured data suggests that the developed test facility and the test technique can be used reliably for the performance test of turbines with the minor improvement.provement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1077-1087
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• 2002

The heat (mass) transfer characteristics on the blade surface of a high-turning first-stage turbine rotor for power generation has been investigated by employing the naphthalene sublimation technique. A four-axis profile measurement system is developed successfully for the measurements of local sublimation depth on the curved surface In the leading edge region, there is a good agreement between the present heat (mass) transfer data and the previous result on a turbine blade with a moderate turning angle, but some discrepancies are found in the mid-chord heat (mass) transfer between the two results. The local heat (mass) transfer on the present suction surface is greatly enhanced due to an earlier boundary transition, compared with that on a turbine blade with a moderate turning angle, meanwhile there is only a slight change in the pressure-side heat (mass) transfer between the two different turbine rotors. In general, the heat (mass) transfer augmentation by the endwall vortices is found much higher on the suction surface than on the pressure surface.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.872-877
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• 2001

This study analyzed the design performance of the bottoming system of combined cycle power plants adopting a single-pressure once-through heat recovery steam generator with reheat. A computer program was constructed and parametric analyses were carried out to present the criteria for determining the reheat pressure and the location of the starring point of the reheater in the HRSG. The performance of the bottoming system was presented for the range from high subcritical to supercritical pressures. It was founded that the power of the bottoming system can be as high as that of the present triple-pressure bottoming system even with a higher exhaust gas temperature. A requirement for this high performance is a proper arrangement of the reheater.

• Journal of KSNVE
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• v.4 no.1
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• pp.23-31
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• 1994

When a shaft is misaligned, a high level of vibration is experienced. As a consequence, the system performance could be low with high level of noise generated. Even, a catastrophic damage of the rotating machinery may happen in the worst situation. The vibration caused by the shaft misalignment is not cured unless a correct alignment of the shaft is investigated. In this paper, a step by step approach for the turbine alignment has been demonstrated. It includes measurement tips of the coupling rim and face, calculation procedure of the bearing level, and the relevant values of the addition and subtration for shims in order to align the shaft level correctly. Then, as an application of the shaft alignment, the turbine system at the Pyung Tek focile electric power plant has been examined. Since the real system consists of high pressure, low pressure turbines and the generator, detailed alignment prolcedures of the multi stage shaft system has been demonstrated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.3917-3925
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• 1996

A numerical analysis on three dimensional turbulent incompressible flows through linear cascades of turbine rotor blades with high turning angles has been performed by using a generalized k-.epsilon. model which is a high Reynolds number form and derived by RNG(renormalized group) method to account for the variation of the rate of strain. A second order upwind scheme is used to suppress numerical diffusion in approximating the convective terms. Body-fitted coordinates are adopted to represent the complex blade geometry accurately. For the case without tip clearance, velocity vectors and static pressure contours are shown to be in good agreement with previous experimental results. For the case with tip clearance, the effects of the passage vortex and tip clearance flow on the total pressure loss as well as their interactions are discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.123-126
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• 2003

The uncertainties generated by measurement parameters are propagated to the uncertainty of total-to-total efficiency on an experiment. The effect of uncertainties’ propagation are analyzed through a turbine performance test. A tested 3-D axial type turbine has a 0.373 degree of reaction at the mean radius and the performance test is conducted at the low pressure and cold temperature status. The uncertainty of turbine inlet and exit total pressure shows the strong propagation effect to the uncertainty of total-to-total efficiency. This means that a high precision pressure measuring system is required to reduce the uncertainty propagated by the pressure. In the uncertainty portion of each measurement parameters to the uncertainty of total-to-total efficiency, the uncertainty by torque is the highest and the uncertainty by RPM is the lowest. In case of the total pressure, the effect of the uncertainty by torque is increased with the increasing RPM. The uncertainty of total pressure at the turbine exit shows more influence to the results than that at the turbine.

• Journal of the Korean Society of Combustion
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• v.15 no.1
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• pp.12-21
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• 2010

The main objective of this study was investigation of combustion instability characteristics in a lean partially premixed gas turbine dump combustor. Dynamic pressure transducers were located on combustor and inlet section to observe combustion pressure oscillation and difference at each measurement places. Also flame shape and $CH^*$ chemiluminescence were measured using a high speed ICCD camera. The combustor length was varied in order to have different acoustic characteristics from 800 to 1090 mm. The first section of this paper shows the stability map in model gas turbine combustor. And the effects of combustor length, mixture velocity in the mixing section and equivalence ratio were studied by the pressure perturbation and heat release oscillation. Also, the instability frequency and mode analysis were studied in last two sections. We observed two dominant instability frequencies in this study. Lower frequencies were obtained at lower equivalence ratio region and it was associated with a fundamental longitudinal mode of combustor length. Higher frequencies were observed in higher equivalence ratio conditions. It was related to secondary longitudinal mode of combustor and mixing section. In this instability characteristics, pressure oscillation of mixing section part was larger than pressure oscillation of combustor. As a result, combustion instability was strongly affected by acoustic characteristics of combustor and mixing section geometry.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.383-391
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• 2009

Vibrations at different frequencies with a different intensity as well as a pressure pulsation with different parameters are two phenomena which can be observed at different water turbines. Due to the vibration and the pressure pulsation some restrictions of water turbine operation range are applied. Similar problems with the efficiency level in a wide water turbine operation range are the basic problems which are solved for ages. A theoretical and practical solution of the above mentioned problems is very much time and money consuming. The paper describes a new theoretical solution of the excitation and pressure pulsation decrease as well as extension of the operational range with high efficiency level. The new concept to decrease the vibrations and pressure pulsations is based on a heterogeneous runner blade geometry generation. The new concept of the runner geometry design was numerically tested at a low specific speed pump turbine, see Fig. 1, and basic points of the concept are presented in this paper.

• Journal of ILASS-Korea
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• v.12 no.1
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• pp.18-29
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• 2007

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle - installed downstream of the high pressure turbine extraction steam line - inside number 5A and 5B feedwater heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes the comparisons between the numerical analysis results using the FLUENT code and the down scale experimental data in an effort to determine root causes of the shell wall thinning of the high pressure feedwater heaters. The numerical analysis and experimental data were also confirmed by actual wall thickness measured by an ultrasonic test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.1 s.256
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• pp.1-7
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• 2007

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle - installed downstream of the high pressure turbine extraction steam line - inside number 5A and 5B feedwater heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure feedwater heater may be affected by flow-accelerated corrosion. This paper describes the comparisons between the numerical analysis results using the FLUENT code and the down scale experimental data in an effort to determine root causes of the shell wall thinning of the high pressure feedwater heaters. The numerical analysis and experimental data were also confirmed by actual wall thickness measured by an ultrasonic test.