• Journal of computational fluids engineering
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• v.15 no.1
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• pp.17-23
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• 2010

Performance improvements of the heat recovery steam generator(HRSG) can be achieved by improving the flow distribution of exhaust gases for a various type of different equipments. A number of design parameters are systematically investigated and their effects on an index of velocity deviation established. The parameters include the three shape of the transition duct and the wide range of the guide vane angles. The numerical results clearly reveal feature of the flow pattern in the transition duct, velocity deviation and pressure drop at tube bank part.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1172-1177
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• 2008

Diverging channel from gas burner exit to the inlet section of Heat Recovery Steam Generator (HRSG) has been re-designed for 1 MW steam supply and power generation system. Three different test geometries have been chosen for the numerical simulation. The existing design for 300 kW HRSG system (CASE B) has been improved by geometry and position changes of inlet guide vanes along with gas velocity entrance angle at the diverging channel inlet (CASE C). Both cases has been compared with the case where hot combustion gas is directly injected without any guide vanes (CASE A). Improved design shows overall uniform velocity and temperature distribution compared to existing design.

• Solar Energy
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• v.17 no.2
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• pp.35-42
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• 1997

Thermal diode is a device which allows heat to be transferred in one direction by convection due to difference of density of fluid, and blocks heat flow in the opposite direction. Vertical plate for heat collection and radiation are of utility for design of thermal diode. It was considered the transient and steady state of air filled thermal diode with guide vane which combined rectangular and parallelogrammic shape enclosures. $Gr^*$ was kept constantly on $1.11{\times}10^{10}{\sim}1.4{\times}10^{10}$ and error range was ${\pm}3%$ during the experiment. Nu was examined when inclined angle are $15^{\cir\c}\;and\;45^{\circ}$ and, also the experiments was carried out with and without guide vane as well. Specially, Nu was linearly increased due to increase of $Gr^*$, and the effect of guide vane and dimensionless channel depth was sensitive. Developed state of temperature began at dimensionless time $0.5{\sim}0.6$ due to variation of inclined angle, which is characteristic of system.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.213-220
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• 1997

In this study, a design for a shape of centrifugal pump impeller has been performed using a p.c. under a Windows environment. Interaction between a user and a computer has been easily established using the Visual Basic. In determining an outer diameter of an impeller, steps are divided into two, a basic computational step and a refinment step. In this way user can enter his/her experience at the refinment step and hence can expect to lessen the nonlinear nature inherent to the design. In determining a shape of a side view of an impeller, the Bezier cubic curve has been used, and it can be seen that the Bezier cubic curves are well suited in the shape design under a Windows environment. By simply manipulating the four control points, one can generate various cubic curves among which one is selected. Also, a simple method, which can determine the curved position of an impeller vane, has been developed. These data can be used for final CAD drawings.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.463-470
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• 2016

A vane shear test (VST) is a simple testing method for determining an undrained shear strength of cohesive soils by minimizing soil disturbance. In this study, the VST was used to determine a shear strength of sand. Dry Nakdong River sand was prepared for loose and dense conditions in a cell and then pressurized with 25, 50, 75 or 100 kPa from the surface of sand. A vane (5 cm in diameter and 10 cm in height) was rotated and a torque was measured within sand. When a torque moment by vane and friction resistance moment by sand is assumed to be equalized, a friction angle can be obtained. When a vane rotates within clay, a uniform undrained shear strength is assumed to be acting on cylindrical failure surface. On the other hand, when it is applied for sand, the failure shape can be assumed to be an octagonal or square column. The relationship between measured torque and resistant force along assumed failure shapes due to friction of sand was derived and the internal friction angle of sand was determined for loose and dense conditions. For the same soil condition, a series of direct shear test was carried out and compared with VST result. The friction angle from VST was between 24-42 degrees for loose sand and 33-53 degrees for dense sand. This is similar to those of direct shear tests.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.295-306
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• 2022

The NOx removal performance of the SCR process depends on various factors such as catalytic factors (catalyst composition, shape, space velocity, etc.), temperature and flow rate distribution of the exhaust gas. Among them, the uniformity of the flow flowing into the catalyst bed plays the most important role. In this study, the flow characteristics in the SCR reactor in the design stage were simulated using a three-dimensional numerical analysis technique to confirm the uniformity of the airflow. Due to the limitation of the installation space, the shape of the inlet duct was compared with the two types of inlet duct shape because there were many curved sections of the inlet duct and the duct size margin was not large. The effect of inlet duct shape, guide vane or mixer installation, and venturi shape change on SCR reactor internal flow, airflow uniformity, and space utilization rate of ammonia concentration were studied. It was found that the uniformity of the airflow reaching the catalyst layer was greatly improved when an inlet duct with a shape that could suppress drift was applied and guide vanes were installed in the curved part of the inlet duct to properly distribute the process gas. In addition, the space utilization rate was greatly improved when the duct at the rear of the nozzle was applied as a venturi type rather than a mixer for uniform distribution of ammonia gas.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.263-266
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• 2009

The mainly objectives of this study was a combustion dynamics and instability characteristics in a model gas turbine dump combustor which is the scale down of GE 7FA+e DLN 2.6 gas turbine combustor. Model gas turbine injector has 2-stage swirl vane and it’s reduced 1/3 size of the original one. The shape of plenum and combustor were designed for similar acoustic characteristics. Inlet air was preheated to $200{\sim}400^{\circ}C$. The flow velocity at mixing nozzle was 30 to 75 m/s and equivalent ratio was 0.4 to 1.2. The combustor length was varied for different acoustic characteristics to $375{\sim}700\;mm$. As the result, this research have been show the combustion instability was observed at lower equivalence ratios ($\Phi$ < $0.5{\sim}0.6$) and higher equivalent ratios ($\Phi$ > $1.1{\sim}1.2$).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.231-235
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• 2009

The mainly objectives of this study was a combustion dynamics and instability characteristics in a model dump type combustor which is scale down of GE 7FA+e DLN 2.6 gas turbine combustor with running at Seo-Inchon combined cycle power plant. Model gas turbine injector has 2-stage swirl vane and it's reduced 1/3 size of the original one. The shape of plenum and combustor were designed for similar acoustic characteristics. As the result, this research have been shows the peak frequency of model combustor was changed quarter-wave mode to Helmholtz resonator mode in plenum and longitudinal mode in dump combustor at unstable flame conditions caused by the different of combustor temperature and fuel-air mixture distributions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.549-554
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• 2011

Recently, technical advances have been made in high efficiency gas turbine power plants. In domestic gas turbine facilities, the material properties of the blade and vane are degraded by the daily start-stop operations arising from the thermo mechanical cycle. We surveyed the time dependent degradation of the HP blade and vane to gather basic data for life assessment and damage analysis. The EOH(equivalent operating hours) of the blades were 23,686, 27,909, and 52,859 and the EOH of the vanes were 28,714 and 52,859, respectively. With increased operating hours, the shape of the primary ${\gamma}$' precipitate transformed from cubic to spherical, and its average size also increased. The leading edge area of the blades and the center of the vanes had the worst morphology, and this tendency agrees with the microhardness results. The thickness of the thermally grown oxide at the outer surface of the bond coat increased with increased operating hours.

• Journal of Environmental Science International
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• v.18 no.7
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• pp.755-765
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• 2009

Some sections of the exhaust system to determine the shape of the duct is to suffer the difficulties by space constraints to install new equipment of the environment post-treatment for existing operation of the power plants. In this paper the large duct in flue gas desulfurization equipments of the 500MW coal-fired power plant on the current operation is numerically analyzed from induced draft fan exit to booster up fan inlet section which is in the narrow space of the exhaust system with four times bending and is connected to emergency duct to bypass the exhaust gas on the emergency operation. The procedure and method using computational fluid dynamics are proposed to maintain the stability of the guide vane with the uniform flow and a minimum pressure loss of exhaust gas in the case of normal and emergency operation between the direction of the flow of exhaust gas duct at different.