Choon-Man Jang

Performance Analysis on the Design Variables of a Turbo Blower

This paper describes the shape optimization of a blower impeller used for a refuse collection system. Two design variables, which are used to define the blade angles of an impeller, are introduced to increase the blower performance. A blower efficiency is selected as an object function, and the shape optimization of the blade angles is performed by a response surface method (RSM). Three-dimensional Navier-Stokes equations are introduced to analyze the internal flow of the blower and to find the value of object function for the training data. Relatively good agreement between experimental measurements and numerical simulation is obtained in the present study. Throughout the shape optimization, blower efficiency for the optimal blade angles is successfully increased up to 3.6% compared with that of reference at the design flow rate. Detailed flow field inside the turbo blower is also analyzed and discussed.

Performance Enhancement of 20kW Regenerative Blower Using Design Parameters

Abstract This paper describes performance enhancement of a regenerative blower used for a 20 kW fuel cell system. Two design variables, bending angle of an impeller and blade thickness of an impeller tip, which are used to define an impeller shape, are introduced to enhance the blower performance. Internal flow of the regenerative blower has been analyzed with three-dimensional Navier-Stokes equations to obtain the blower performance. General analysis code, CFX, is introduced in the present work. SST turbulence model is employed to estimate the eddy viscosity. Throughout the numerical analysis, it is found that the thickness of impeller tip is effective to increase the blower efficiency in the present blower. Pressure is successfully increased up to 2.8% compared to the reference blower at the design flow condition. And efficiency is also enhanced up to 2.98 % compared to the reference one. It is noted that low velocity region disturbs to make strong recirculation flow inside the blade passages, thus increases local pressure loss. Detailed flow field inside the regenerative blower is also analyzed and compared.

Evaluation of Inflow Uniformity on the Performance of Double-Inlet Centrifugal Blower Using Optimal Design Method

This paper presents the performance enhancement of a double-inlet centrifugal blower by the shape optimization of an inlet duct. Two design variables, a length of anti circulation vane and an angles of inlet guide, are introduced to improve the inlet flow uniformity leading to the blower performance. Three-dimensional Navier-Stokes equations are used to analyze the blower performance and the internal flow of the blower. From the shape optimization of the inlet duct of the double-inlet centrifugal blower, the optimal positions of each design variable are determined. Throughout the analysis of sensitivity, it is found that the angle of the inlet guide is more effective than the length of the anti-circulation vane to increase flow uniformity at the outlet of the duct. Efficiency and pressure for the optimal inlet duct shape are successfully increased up to 3.55% and 3.2% compared to those of reference blower at the design flow condition, respectively. Detailed flow field inside the blower is also analyzed and compared.

Performance Evaluation of a Centrifugal Blower Using Optimal Design Method

Effects of design variables on the performance of a centrifugal blower have been analyzed based on the three-dimensional flow analysis. Two design parameters defined the shape of a volute casing are introduced to enhance a blower performance. To analyze three-dimensional flow field in the centrifugal blower, general analysis code, CFX, is employed in the present work. SST turbulence model is employed to estimate the eddy viscosity. Boundary condition at the interference plane between rotational and stationary domains is applied by a stage method. Unstructured grids are used to represent a composite grid system including blade, casing and inlet guide.In the present study, throughout the shape optimization of the centrifugal blower at the design flow condition, the blower efficiency and pressure are successfully increased by 0.5 and 1.6 percent compared to reference one. It is found that the casing height of design variables is more sensitive on the object function of efficiency compared to that of the casing width. And secondary flow due to velocity gradient and low velocity region increase pressure loss, leading to make low efficiency. Detailed flow field inside a centrifugal blower is also analyzed and compared.Copyright

Pressure Characteristics According to the Duct Shapes of Turbo Blowers Connected in Serial

Pressure characteristics according to the duct shapes of turbo blowers connected in serial have been performed to reduce pressure loss in the piping system. To analyze three-dimensional flow field in the turbo blower system, general analysis code, CFX, is introduced in the present work. SST turbulence model is applied to estimate the eddy viscosity. Throughout the numerical simulation for the turbo blower system having a various shape of a inlet guide, optimal inlet guide can be selected. It is found that the pressure loss in the piping system having the optimal inlet guide can be reduced by minimizing the inflow distortion at the upstream of the impeller. Detailed flow analysis of the blower system serially connected is also performed and analyzed.

Optimal design and operation of a turbo blower used for refuse collection system

Optimal operation of turbo blowers connected in serial is analyzed by experimental measurements and numerical simulation with three-dimensional Navier-Stokes equations. The turbo blower system considered in the present study is widely used for the refuse collection system. Design optimization of the turbo blower using some design variables is also studied to enhance the performance of the blower. Throughout numerical simulation, it is found that the input energy reduction by optimal operation of the turbo blowers with the proper changes of the rotor`s rotating frequency can be reduced a input energy for operating the blower system compared to the conventional on-off operation method theoretically. It is also found that the optimal design method is effective to enhance the performance of the turbo blower.

Numerical Analysis of a Tip Leakage Vortex in an Axial Flow Fan

Three-dimensional vortical flow and separated flow topology near the casing wall in an axial flow fan having two different tip clearances have been investigated by a Reynolds-averaged Navier-Stokes (RANS) flow simulation. The simulation shows that the tip leakage vortex formed close to the leading edge of the blade tip on suction side grows in the streamwise direction. On the casing wall, a separation line is formed upstream of the leakage vortex center due to the interference between the leakage vortex and main flow. The reverse flow is observed between the separation line and the attachment line generated downstream of the trailing edge, and increased with enlarging tip clearance. The patterns of a leakage velocity vector including a leakage flow rate are also analyzed according to two tip clearances. It is noted that the understanding of the distribution of a limiting streamline on the casing wall is very important to grasp the characteristics of the vortical flow in the axial flow fan.

Structural Characteristics for the Hybrid Street-Lamp of a Small Wind Turbine and Photovoltaic Power System

In the present study, structure analysis has been performed to understand the deflection and stress distribution for a hybrid street-lamp having a vertical-axis wind turbine and a photovoltaic panel. Modal analysis is also evaluated to avoid resonance gerenerated by sychronism between a turbine and a lamppost. To analyze deflection, stress and frequency, general analysis code(ANSYS-Mechanical 13) is employed in the present work. Throughout structure analysis in the hybrid street-lamp, maximum stress is observed at the connecting position between a turbine blade and a blade supporter. Campbell diagram which is combined the natural frequency of turbine blades and blade passing frequency is presented to analyze a system resonance. It is found that the resonance of the system having a rotating turbine blade and a lamppost can avoid by the optimal selection of geometric parameters of a wind turbine.

Desulfurization of Biogas Using Micro Bubble in a Biogas Plant

Abstract >> This paper describes the reduction of a hydrogen sulfide (H 2 S) generated from a biogas plant. Microbubble system is adopted to supply air into the water in the reaction chamber, which can increase the contactarea of the supplied air to the reserving water. Two stage reaction chambers having two reaction rooms are designedand manufactured to enhance the reduction rate of a hydrogen sulfide. Sodium hydroxide (NaOH) is also considered to get rid of a hydrogen sulfide. Air volume rate to the water in a reaction chamber is maintained between 0.5and 1.0m 3 /min. Throughout experimental measurement of the concentration of a hydrogen sulfide by changing thevolume of supplied air into the water, reduction rate of a hydrogen sulfide increases as air volume increases. Addingsodium hydroxide to the water with the air supply can reduce effectively a hydrogen sulfide up to 99.5% from biogas. It is noted that a hydrogen sulfide generated by a biogas plant can reduce by supplying micro bubbleair and sodium hydroxide effectively.

Parametric Study for Optimal Design of a Piping System in a Serially Connected Multi‐Stage Turbo Blower

Optimal design of a piping system connected in the multi‐stage turbo blower has been performed using response surface method and three‐dimensional Navier‐Stokes analysis to reduce pressure loss in the piping system. To analyze three‐dimensional flow field in the piping system including a multi‐stage turbo blower, general analysis code, CFX, is employed in the present work. SST turbulence model is employed to estimate the eddy viscosity. Unstructured grids are used to represent a composite grid system including circular duct, blower impeller, casing and gate valve. Throughout the optimization of a piping system using two design variables defined the radius of an inlet and outlet ducts, the pressure loss in the piping system is successfully reduced by decreasing local losses in the piping system. Detailed flow analysis is performed using the reference and optimum shape of the connecting duct.