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김현종,Nanjundan Parthasarathy,최윤환,이연원 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3
A 2D rectangular tank subjected to horizontal excitations is used to analyze the effects of sloshing. The tank is fitted with horizontal baffles on two sides to suppress the impact pressure of sloshing by using an air-trapping mechanism. The volume of fluid method is adopted to create sloshing phenomena. Five cases with fixed baffle gaps and various baffle lengths are used to analyze the effects of suppressing the sloshing impact pressure in the tank. The peak pressure values of the cases with baffles are compared with those of the cases without baffles. Results show that the maximum suppression rate achieved is 63.6 % due to air trapping and baffle effects. Baffle ratio (Defined by G/L), a geometrical dimensionless factor, is considered to analyze the effects of baffle length and gap. A baffle ratio of 0.5 results in a 14.2 % reduction in the sloshing impact rate. An increasing amount of air is trapped within the baffle array as BR decreases.
Hyunjong Kim,Parthasarathy Nanjundan,Junho Jeon,Yeon-Won Lee 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.7
The performance of the air-trapping mechanism to suppress sloshing impact pressure in a prismatic tank was numerically evaluated. In order to implement the air-trapping mechanism, a short horizontal baffle array was installed on either side of the tank to collect air by the sloshing flow. The impact pressure change was analyzed by setting the ratio of the baffle length to the tank width as a parameter, and the pressure distribution on the wall was observed through eight calculation points (CPs) set between the baffles in the direction of tank height. The suppression performance of impact pressure was evaluated using Eulerian- Eulerian multiphase model to consider the water-air two-phase flow. The visualization results show the generation of sloshing impact pressure and the effects of the air-trapping mechanism. Quantitative comparisons of time series results of pressure were performed using peak pressure comparison and fast Fourier transform (FFT) analysis. The overall sloshing impact pressure reduction was 58.2 % in the FFT analysis and the maximum reduction rate was 70.4 %.
Numerical study on design for wave energy generation of a floater for energy absorption
LI KUIMING,Nanjundan Parthasarathy,최윤환,이연원 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.12
In order to design a wave energy generating system of a floater type, a 6-DOF motion technique was applied to the three-Dimensional CFD analysis on a floating body and the behavior was interpreted according to the nature of the incoming waves. Waves in a tank model were generated using a single floater comparing with that of a Pelamis wave energy converter. In this paper, we focus on four variables,namely the wave height, angular velocity, diameter and length of the floater. The process was carried out in three stages and it was found that there are energy absorption differences in different parameters of wave height, length and the diameter of a floater during simulation,thus leading for the necessity of an optimal design for wave energy generation.
Mohan Kumar Dey,Nanjundan Parthasarathy,이연원 한국마린엔지니어링학회 2020 한국마린엔지니어링학회지 Vol.44 No.4
In this numerical study, the hairpin type shell and tube heat exchanger is analyzed for heating the cryogenic liquefied natu-ral gas (LNG). The cryogenic LNG is passed through the tube side and is heated by the hot water on the shell side of the hairpin heat exchanger. In order to increase the performance of the heat exchanger, maximum heat needs to be extracted from the hot water and transferred to the LNG stream. Thus, different arrangement of shell and tube sides of the hairpin heat exchanger are used to study the pressure drop in the hot water and to increase the temperature of the LNG. The effects of horizontal and vertical baffles orientation, staggered and aligned tube bank arrangements, baffles number (6, 8, 10 and 12), and baffles cut percentages were used to analyze the pressure drop and temperature difference in the exchanger. The results show that the pressure drop is decreased and the tube outlet temperature is increased in the heat exchanger for the percentage of baffle cut changes from 22.5% to 37.5%. Also, increasing the number of baffles increases both the temperature and pressure drop in the hairpin heat exchanger. Furthermore, comparing horizontal and vertical baffle orientation, pressure drop is always lower and LNG outlet temperature is always higher in the horizontal baffle orientation for both tube bank arrangement systems. However, in the horizontal baffle orientation the pressure drop for staggered tube bank arrangement is smaller than that of aligned tube bank arrangement, but the temperature of aligned tube bank is higher compared to the staggered tube bank arrangement.