• The KSFM Journal of Fluid Machinery
• /
• v.16 no.1
• /
• pp.11-16
• /
• 2013

A numerical study was conducted to improve the performance of an impeller of centrifugal compressor. Nine design variables were chosen with constraints. Only meridional contours and blade profile were adjusted. ANN (Artificial Neural Net) was adopted as a main optimization algorithm with PSO (Particle Swarm Optimization) in order to reduce the optimization time. At first, ANN was learned and trained with the design variable sets which were obtained using DOE (Design of Experiment). This ANN was continuously improved its accuracy for each generation of which population was one hundred. New design variable set in each generation was selected using a non-gradient based method of PSO in order to obtain the global optimized result. After $7^{th}$ generation, the prediction difference of efficiency and pressure ratio between ANN and CFD was less than 0.6%. From more than 1,200 design variable sets, a pareto of efficiency versus pressure ratio was obtained and an optimized result was selected based on the multi-objective function. On this optimized impeller, the efficiency and pressure ratio were improved by 1% and 9.3%, respectively.

• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.4
• /
• pp.395-403
• /
• 2020

In this paper, the performance characteristics of the impeller and volute in the 2 vane pump were investigated using response surface method (RSM) with commercial computation fluid dynamics (CFD) code. Design variables were defined with the impeller blade angle and volute area distribution. The objective functions were defined as the total head, total efficiency and solid material size of the 2 vane pump. The design optimization of the design variables was determined using the RSM. The numerical results for the reference and optimum models were compared and discussed in this work.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.3
• /
• pp.51-59
• /
• 2006

The physical characteristics of autonomic microcapsules manufactured with various agitation speeds in a stirred tank were observed experimentally by a particle size analyzer and an optical microscope. The flow characteristics in a stirred tank were also investigated through a 3-dimensional numerical simulation to understand the manufacturing process of autonomic microcapsules. According to the results, we found that the agitation speed was the important factor to determine the sizes of microcapsules. The impeller-induced flow allowed the jet and tip-vortex pair components in the mixed fluid of a stirred tank. The vorticity around the blades in the impeller was increased as increasing the agitation speed. In addition, the size of autonomic microcapsules was strongly affected on the small scale mixing pattern such as a tip-vortex pair.

• 한국전산유체공학회:학술대회논문집
• /
• 2007.10a
• /
• pp.92-99
• /
• 2007

In this paper, optimization of the vaned centrifugal compressor was carried out at a given mass flow rate condition. Firstly, impeller optimization was conducted using response surface method (RSM) which is one of optimization methods. After the optimization of the impeller was completed, diffuser optimization was performed with the optimized impeller. In these processes, Navier-Stokes solver was used to calculate the flow inside the centrifugal compressor. And the optimization is performed with Box-Behnken design method which is efficient for fitting second-order response surfaces to reduce the number of calculations required. As a result, compared with the reference model, the efficiency and the pressure ratio of the optimized impeller and diffuser are found to be increased. The performance at off-design conditions is presented.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2001.05a
• /
• pp.117-121
• /
• 2001

A numerical simulation was conducted to investigate the effect of height position of Rushton type Impeller in the fermentation. The computational method was based on the CFX code. The simulation was performed for 3 height differences(25, 30, 35mm) between Rushton type impeller and bottom of fermentation. The instantaneous flow fields showed that the bulk flow consisted of large scale vortices. However the main flow results showed that the formation of ring vortices above and below the impeller depended on the height of the impeller.

• Transactions of the Korean hydrogen and new energy society
• /
• v.32 no.4
• /
• pp.277-284
• /
• 2021

This paper deals with multi-objective optimization using response surface method to improve the hydraulic performances of a 2 vane pump for wastewater treatment. For analyzing the internal flow field in the pump, steady Reynolds-averaged Navier-Stokes equations were solved with the shear stress transport turbulence model as a turbulence closure model. The impeller and volute variables were defined in the shape of the 2 vane pump. The objective functions were set to satisfy the total head at the design flow rate as well as to improve the efficiency. The hydraulic performance of the optimally designed shape was verified by numerical analysis results.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.51 no.9
• /
• pp.431-437
• /
• 2002

Low hemolysis is one of the key factors in the production of successful rotary blood pumps. It is, however, difficult to identify the areas where hemolysis occurs. Computational fluid dynamics(CFD) analysis enables the engineer to predict hemolysis on a computer Fluid dynamics in five different axial flow pumps was analyzed 3-dimensionally using CFD software. The impeller was rotated at a speed which supplied a flow of 5L/min at a pressure difference of 100mmHg. Changes in the turbulent kinetic energy along streamlines through the pumps were computed. Reynolds' shear stress( (equation omitted) ) was calculated using the turbulent kinetic energy. Hemolysis was evaluated based on Reynolds'shear stress and its exposure time(t) : dHb/Hb=3.62$\times$10$^{-5}$ $t^{0.785}$$\tau$$^{2.416}$ . Hemolysis of the pumps was measured in vitro using fresh bovine blood to which citrate phosphate dextrose was added to prevent clotting. A pump flow of 5L/min was maintained at a pressure difference of 100mmHg for 3h. The normalized index of hemolysis(NIH) as measured. Reynolds' shear stress was high behind the impellers. The measured NIH and the calculated hemolysis(dHb/Hb) shoed a good correlation; NIH=0.0003(dHb/Hb) (r=0.90, n=6) in the range of NIH between 0.003 and 1.1. CFD analysis can predict the in vitro results of hemolysis as well as the areas where hemolysis occurs.ysis occurs.

• 유체기계공업학회:학술대회논문집
• /
• 2001.11a
• /
• pp.159-164
• /
• 2001

An extensive range of pumping facilities are employed in the regional water supply system in metropolitan areas, and optimization and the systematic combination of the pump facilities have direct bearing on the stability and economy of the water supply system concerned. These systems must be able to guarantee stability, efficiency and offer high reliability. Preparation of metropolitan area regional water supply system construction project must include a basic plan which takes into account the suitability of pumping facilities to be used, the environment in which facilities will be installed, man-power requirements and basic operational and management policies. This paper contains over-all analysis of the management of metropolitan area regional water supply systems and highlights the cause of Inefficiency and energy waste and puts forward a remedial plan of action. In addition, pump/motor specification programs were developed using Visual Basic to assist selection of the same.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.1
• /
• pp.121-129
• /
• 2022

With the recent increase in international trade volume the trade volume through ships is also continuously increasing. The treatment of ballast water goes through the following five steps, samples are taken and analyzed at each step, and samples are obtained using a suction pump. These suction pumps have low efficiency and thus need to be improved. In this study, it is to optimize the form of the impeller which affects directly improvements of performance to determine the capacity of suction pump and to fulfill the purpose of this research. To do it, we have carried out parametric design as an input variable, geometric form for the impeller. By conducting the flow analysis for the optimum form, it has confirmed the value of improved results and achieved the purpose to study in this paper. It has selected the necessary parameter for optimizing the form of the pump impeller and analyzed the property using experiment design. And it can reduce the factor of parameter for local optimization from findings to analyze the property of form parameter. To perform MOGA(Multi-Objective Genetic Algorithm) it has generated response surface using parameters for local optimization and conducts the optimization using multi-objective genetic algorithm. with created experiment cases, it has performed the computational fluid dynamics with model applying the optimized impeller form and checked that the capacity of the pump was improved. It could verify the validity concerning the improvement of pump efficiency, via optimization of pump impeller form which is suggested in this study.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.448-453
• /
• 2016

Erosion and abrasion caused by cavitation damage occur in fluid equipment, such as ships or impellers. Similarly, the equipment damage from noise and vibration can shorten its life. This study analyzed the importance of the parameter characteristics of the process optimization of HVOF (High Velocity Oxygen Fuel spraying), which is generally used in a variety of industries for enhancing the resistibility from the cavitation phenomenon. The surface of the ALBC3 substrate was coated with an amorphous powder as a filler metal according to the experimental design using the Taguchi method, and then the characteristics with each parameter were analyzed using a porosity measurement test. The optimal process conditions was a combustion pressure of 80psi, coating distance of 270mm, gun speed of 200mm/s, and powder feed rate of 25g/min as a result of the HVOF coating by applying the experimental design. The combustion pressure, coating distance and powder feed rate were more than 25% and indicated a similar contribution rate, but the contribution rate of the gun speed was 19%, which was slightly less than the others. The contribution rate with each parameter was only slightly significant. On the other hand, all four parameters were found to be important in the contribution rate aspects of the HVOF coating process.