• Journal of Energy Engineering
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• v.13 no.2
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• pp.118-127
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• 2004

The purpose of this study is experimentally to analyze that intake port swirl, injection system and turbocharger have an effect on the engine performance and the emission characteristics in a V8 type turbocharged intercooler D.I. diesel engine of the displacement 16.7ι, and to suggest the improvement of engine performance. Generally to enhance engine power, TCI diesel engine is put to practically use turbo-charged intercoler in order to increase boost efficiency which is cooled boost air. As results of considering the factors of the intake port of swirl ratio 2.25, compression ratio 17.5, re-entrant 8.5$^{\circ}$ combustion bowl, nozzle hole diameter ${\Phi}$0.33*3+${\Phi}$0.35*2, nozzle protrusion 3.18mm, injection timing BTDC 12$^{\circ}$CA and turbo charger (compressor 0.6A/R+46Trim, turbine 1.0A/R+57Trim) is the best in the full range of operating in the engine performance and the exhaust characteristics of NO$\_$x/ concentration. Therefore their factors are appropriated as intake system, injection and turbocharger system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.627-630
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• 2009

Ejector system can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an configuration and operating conditions for an ejector in the condition of sonic and subsonic. Experimental and theoretical investigation on the sonic and subsonic ejectors with a converging-diverging diffuser was carried out. Numerical simulation was adopted for an optimal geometry design and satisfying the required performance. Also, some ejectors with a various of nozzle throat and mixing chamber diameter were manufactured precisely and tested for the comparison with the calculation results.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.46-53
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• 2017

This paper deals with an acoustic model for a lean premixed gas turbine combustor composed of three stages: premixing chamber, nozzle and flame tube. Our model is given as an acoustic transfer function whose input is a heat release rate perturbation and output is a velocity perturbation at a flame location. We have shown that the resonance frequencies are functions of three round-trip frequencies of acoustic wave in each stage, and area ratios between stages. By analyzing poles of the acoustic transfer function, we could characterize resonant frequencies and their dependency on various system parameters of a combustor. It was found that our analytic findings match with existing numerical and experimental results in literature.

• Journal of the Korean Institute of Gas
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• v.24 no.4
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• pp.25-31
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• 2020

Experimental investigations were conducted to examine the combustion characteristics of a swirl-stabilized double cone premixed burner nozzle used for industrial gas turbines for power generation. Several variants with different fuel injection patterns are tested to compare the combustion characteristics such as NOx and CO emissions, stability, and wall temperature distributions. Main results show that NOx emissions and stability are decreased either when the fuel hole diameter is decreased with the same number of fuel holes, or when the number of fuel holes is reduced with the same total area of fuel holes, both of which are due to a higher penetration of fuel into the air stream. Not only is NOx reduced but also stability is enhanced when the fuel hole diameter varies in an alternating manner with the same total area of fuel holes, showing that NOx reduction is due to a higher penetration of mean fuel injection path while stability enhancement is due to a lowered penetration of minimum fuel injection path.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4093-4099
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• 2014

In this study, the thermal-structural behavior of the combustor assembly of 200 kW micro gas turbine system was performed. The typical combustor assembly consists of a Liner, Inner & Outer Case, Burner and Nozzle ring, etc. There are some gaps and friction elements between the components to compensate for the different thermal expansions of various components. Therefore, the developed finite element model includes nonlinear elements. The boundary support conditions of the combustor assembly significantly affect the stress distribution due to the high temperature gradient. This paper deals with parametric studies to quantitatively determine the effects of the variation of the support conditions on the stress distribution and deformation of various components of combustor assembly. These results may be useful for the design of the combustor assembly.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.128-133
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• 2005

In this study, performance design programs for components of a turbopump unit (TPU) in a Liquid Rocket Engine (LRE), that has non-cryogenic centrifugal pumps and 1-stage impulse turbine with partial admission nozzle, were developed. The programs were integrated in a TPU module by balancing the mass flow rate for pump-turbine power, and the module was inserted into the LRE system conceptual design program. The fundamental design conditions, satisfying LRE system requirements and minimum mass flow rate condition of gasgenerator, were found and compared with data from a Russian liquid rocket engine.

• The KSFM Journal of Fluid Machinery
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• v.12 no.3
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• pp.44-52
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• 2009

Small scale steam turbines are used as mechanical drivers in chemical process plant or power generators. In this study, a design technology was developed for a 100kW class steam turbine which will be used for removing $CO_2$ from the emission gas on a reheated cycle system. This turbine is operated at a low inlet total pressure of $5\;kgf/cm^2$. It consists of two stages and operates at the partial admission. For the meanline analysis, a performance prediction method was developed and it was validated through the performances on the operating small steam turbines which are using at plants. Their results showed that the output power was predicted within 10% deviation although the steam turbines adopted in this analysis were operated at different flow conditions and rotor size. The turbine blades was initially designed based on the computed results obtained from the meanline analysis. A supersonic nozzle was designed on the basis of the operating conditions of the turbine, and the first stage rotor was designed using a supersonic blade design method. The stator and second stage rotor was designed using design parameters for the blade profile. Finally, Those blades were iteratively modified from the flow structures obtained from the three-dimensional flow analysis to increase the turbine performance. The turbine rotor system was designed so that it could stably operate by 76% separation margin with tilting pad bearings.

• Journal of KSNVE
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• v.11 no.3
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• pp.410-415
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• 2001

This paper describes an experimental analysis for improving the stability of blade failure due to the vibration resonance, which happens in the low-pressure steam turbine. Some cracks due to high cycle fatigue were found in the blades of a low-pressure turbine after long time operation. Impact test showed that such failure was mainly caused by the resonance. In other words, since one of the natural frequencies of the grouped blade is very close to the excitation frequency of the nozzle, the resonant vibration leads to a large amplitude of displacement and results in a large amount of stress that may cause fatigue failures in the blades. It is interesting that the blade failures occur only at blades neighboring with the nodal points of the natural vibration mode whose natural frequency is close to the nozzle passing frequency. The effective methods for increasing the reliability against the blade vibration are a heightening the fatigue limit of the blade using an advanced material and a removing the resonance away from the operating speed. It is well known that the removal of theresonance could be obtained by the installation of different types of shrouds, wires, and links between the blades as well as by the chance of the number of nozzles. In the present work, two kinds of modification for avoiding the resonance haute been considered; 1) slot-type finger, 2) long span cover. Full-scale mockup tests have been performed in order to confirm the verification for modification in the shop. Test results show that the use of long span cover is very useful to change the natural frequencies of the grouped blade and to avoid the resonance effectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.100-109
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• 2003

A performacne simulation model of the PT6A-62 turboprop engine using the $SIMULINK^R$ was proposed to predict transient and steady state behaviors. The $SIMULINK^R$ has several advantages such as user-friendliness due to the GUI(Graphic User Interfaces) and ease in the modification of the computer program. The $SIMULINK^R$ model consists of subsystems to represent engine gas path components such as flight initial subsystem, compressor subsystem, burner subsystem, compressor turbine subsystem, power turbine, exhaust nozzle subsystem and integrator subsystem. In addition to subsystems, there are search subsystems to find an appropriate operating point by scaling from the 2-D components look-up table, Gasprop Subsystem to calculate the gas property precisely. In case of steady state validation, performance results analyzed by the proposed $SIMULINK^R$ model were agreed well with the analysis results by the commercial GASTURB program. Moreover in validation of the transient model, it was found that performance simulation results by the proposed model were reasonable agreement with analysis results by the well-proved computer program using FORTRAN.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.248-250
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• 2017

The Mar-M-247 alloy is one of the most widely used materials for gas turbine components in aerospace filed and it shows excellent high temperature strength properties. Hot section parts, such as turbine nozzle and blade, are difficult to manufacture because of their complicated shape. So, the joining process usually applies to them. In this study, the high-temperature behavior of Mar-M-247 alloy at liquid diffusion bonding was investigated. Thus, we performed the diffusion bonding at $1,121^{\circ}C$ for 7 minutes, and observed changes in high temperature strength. As a result, the strength of the bonded specimens decreased by about 70% at $649^{\circ}C$, 60% at $825^{\circ}C$, and 45% at $1,000^{\circ}C$ compared to the base metal. As a result of observing the strength change with bonding time, the specimen bonded for 720 minutes showed a similar strength with the base metal at $649^{\circ}C$. Inferring this result, the joint is considered to be the one-body part.