scispace - formally typeset
Search or ask a question
Author

Jong-Chun Park

Bio: Jong-Chun Park is an academic researcher. The author has contributed to research in topics: Wake & Turbulence. The author has an hindex of 2, co-authored 5 publications receiving 5 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a SUBOFF model assumed as an axial-symmetric body was used to generate wake and the cross-sectional distribution of the time-averaged mean wake and turbulent kinetic energy was compared with the experiments.
Abstract: This paper covers the numerical studies performed to investigate the characteristics of turbulent wake generated by a submarine, SUBOFF model. A SUBOFF model assumed as an axial-symmetric body was used to generate wake. The numerical simulation was performed by using a commercial S/W, FLUENT, with the same condition as the experiments by Shin et al.(2009). Mainly the cross-sectional distribution of the time-averaged mean wake and turbulent kinetic energy was compared with the experiments. Both results are agreed well with each other in the propeller wake section, but the agreement between both is not so satisfied in the far wake field. It means that more numerous number of grid points and their concentration should be required in that field. ※Keywords: Turbulent wake(난류항적), Turbulent kinetic energy(난류운동에너지), SUBOFF model(SUBOFF 모형), CFD simulation(CFD 시뮬레이션), Turbulent Intensity(난류강도)

3 citations

Journal ArticleDOI
TL;DR: In this article, a SUBOFF nude model which was assumed as an axial-symmetric body was used to create wake, and a thin strut was mounted on the top of the model to measure the turbulence in wake cross-section at the distance range of 0.0~2.0L from the model.
Abstract: This paper presents the experimental result to investigate the characteristics of turbulent wake generated by submarine. A SUBOFF nude model which was assumed as an axial -symmetric body was used to create wake, and a thin strut was mounted on the top of the model. The experiments were conducted in a circulating water channel(CWC), and a hot-film was used to measure the turbulence in wake cross-section at the distance range of 0.0~2.0L from the model. The hot film anemometer measured turbulent velocity fluctuations, and the timeaveraged mean velocity and turbulent intensity are obtained from the acquired time-series data. Measured results show well the general characteristics of turbulent intensity, kinetic energy and mean velocity distribution. Also, experimental equations are derived. These experimental equations show well the general characteristics of the turbulent wake behind the submerged body with simple configuration.

2 citations

Journal ArticleDOI
09 Jul 2021
TL;DR: In this paper, the efficiency of PBCF installed at a bulk carrier was estimated under both Propeller Open Water (POW) and self-propulsion conditions through Computational Fluid Dynamics (CFDs) simulation.
Abstract: In this paper, the efficiency of Propeller Boss Cap Fins (PBCF) installed at the bulk carrier was estimated under both Propeller Open Water (POW) and self-propulsion conditions. For this estimation, virtual model-basin tests (resistance, POW, and self-propulsion tests) were conducted through Computational Fluid Dynamics (CFDs) simulation. In the resistance test, the total resistance and the wake distribution according to ship speed were investigated. In the POW test, changes of thrust, torque coefficient, and open water efficiency on the propeller according to PBCF installation were investigated. Finally, the International Towing Tank Conference (ITTC) 1978 method was used to predict the effect of PBCF installation on self-propulsive coefficient and brake horsepower. For analyzing incompressible viscous flow field, the Reynolds-Averaged Navier–Stokes (RANS) equation with SST k-ω turbulence model was calculated using Star-CCM+ 11.06.010-R8. All simulation results were validated by comparing the results of model tests conducted at the Korea Research Institute of Ships and Ocean Engineering (KRISO). Consequently, for the self-propulsion test with the PBCF, a 1.5% reduction of brake horsepower was estimated in the simulation and a 0.5% reduction of the brake horsepower was estimated in the experiment.

2 citations

Journal ArticleDOI
TL;DR: In this paper, a planing hull was used to generate bubble wake at the Circulating Water Channel (CWC) in order to measure bubble wake measurement, the manufactured model is one meter in length and uniform velocity to generate the bubble at CWC is 3m/s, relatively higher speed than conventional hull form.
Abstract: This paper presents bubble wake measurement results generated by the planing hull. The bubble was generated by SNAME TMB model(No. 4876) with hard chine at the CWC(Circulating Water Channel). ABS(Acoustic Bubble Spectrometer) was used to measure bubble wake measurement. The manufactured model is one meter in length and uniform velocity to generate the bubble at CWC is 3m/s, relatively higher speed than conventional hull form. Measurements were performed successfully and measured results show well the general characteristics of bubble wake generated by planing hull. Furthermore, experimental equations are proposed for the practical use.

1 citations

Journal ArticleDOI
TL;DR: In this article, a self-propelled SUBOFF model was used to create wake, and a thin strut was mounted on the topside of the model to measure the turbulence in wake cross-section at the distance range of 0.0∼2.0L from the model.
Abstract: This paper presents experimental results and derived experimental equations to investigate the turbulent wake characteristics generated by the self-propelled SUBOFF submarine model. A self-propelled SUBOFF model which was assumed as an axial-symmetric body was used to create wake, and a thin strut was mounted on the topside of the model. The experiments were conducted in a circulating water channel(CWC), and the hot-film was used to measure the turbulence in wake cross-section at the distance range of 0.0∼2.0L from the model. The hot film anemometer measured turbulent velocity fluctuations, and the time-averaged mean velocity and turbulent intensity are obtained from the acquired time-series data. Measured results show well the general characteristics of turbulent intensity, kinetic energy and mean velocity distribution. Also, this paper presents derived experimental equations, which is extended result to the reference [1]. These experimental equations show well the general characteristics of the turbulent wake behind the self-propelled submerged body.

Cited by
More filters
Journal ArticleDOI
TL;DR: In this paper, the effects of different sail leading edges on the submarine flow field and hydrodynamic noise are investigated by combining the WMLES S-Omega turbulence model and the Ffowcs Williams-Hawkings equation.

6 citations

Journal ArticleDOI
31 Aug 2014
TL;DR: In this paper, the variation of numerical solutions according to the grid number, the distance of the first grid point off the ship surface, turbulence modeling and discretization was investigated.
Abstract: The current work investigated the variation of numerical solutions according to the grid number, the distance of the first grid point off the ship surface, turbulence modeling and discretization. The subject vessel is KVLCC. A commercial code, Gridgen V15 and FLUENT were used the generation of the ship hull surface and spatial system and flow computation. The first part of examination, the effect of solutions were accessed depending on the grid number, turbulence modeling and discretization. The second part was focus on the suitable selection of the distance of the first grid point off the ship surface: YP+. When grid number and discretization were fixed the same value, the friction resistance showed differences within 1 % but the pressure resistance showed big differences 9 % depending on the turbulence modeling. When YP+ were set 30 and 50 for the same discretization, friction resistance showed almost same results within 1 % according to the turbulence modeling. However, when YP+ were fixed 100, friction resistance showed more differences of 3 % compared to YP+ of 30 and 50. Whereas pressure resistance showed big differences of 10 % regardless of turbulence modeling. When turbulence modeling and discretization were set the same value, friction, pressure and total resistance showed almost same result within 0.3 % depending on the grid number. Lastly, When turbulence modeling and discretization were fixed the same value, the friction resistance showed differences within 5~8 % but the pressure resistance showed small differences depending on the YP+.

3 citations

Journal ArticleDOI
TL;DR: In this article, a SUBOFF model assumed as an axial-symmetric body was used to generate wake and the cross-sectional distribution of the time-averaged mean wake and turbulent kinetic energy was compared with the experiments.
Abstract: This paper covers the numerical studies performed to investigate the characteristics of turbulent wake generated by a submarine, SUBOFF model. A SUBOFF model assumed as an axial-symmetric body was used to generate wake. The numerical simulation was performed by using a commercial S/W, FLUENT, with the same condition as the experiments by Shin et al.(2009). Mainly the cross-sectional distribution of the time-averaged mean wake and turbulent kinetic energy was compared with the experiments. Both results are agreed well with each other in the propeller wake section, but the agreement between both is not so satisfied in the far wake field. It means that more numerous number of grid points and their concentration should be required in that field. ※Keywords: Turbulent wake(난류항적), Turbulent kinetic energy(난류운동에너지), SUBOFF model(SUBOFF 모형), CFD simulation(CFD 시뮬레이션), Turbulent Intensity(난류강도)

3 citations

Journal ArticleDOI
30 Jun 2015
TL;DR: In this paper, the authors propose an approach to improve the performance of the RANS system by introducing a new RANS-based approach to the problem of RANS, which is based on the concept of "RANS".
Abstract: 수중운동체의 설계에 있어서 주행 및 조종안정성을 확보하는 것은 매우 중요하다. 특히 조종특성 및 주행 안전성을 결정하는 타 설계에 있어 횡동요 계수에 대한 연구는 필수적이다. 일반적으로 수중운동체의 횡동요 계수에 대한 해석은 원추형 운동실험에 의한 모형실험에 의존하고 있으나, 원추형 운동실험에서는 시험조건상 추진기 회전효과를 고려할 수 없어 정확한 횡동요 계수 도출에 제약을 받으므로 추진기 회전 효과를 고려한 전산해석이 요구된다.수중운동체 주위의 유동특성 및 조종특성에 관한 연구는 다양하게 수행되어졌으며, Liu and Huang[1]은 수중운동체 주위의 유동을 실험을 통해 연구하였으며, Donaldson et al.[2]은 수중운동체 주위의 유동을 포텐셜 코드와 RANS 코드를 사용하여 연구하였다. Gross et al.[3]은 다양한 난류모델을 수중운동체 형상에 적용하여 계산하였고 받음각에 따른 결과 차이를 나타내었다. 횡동요 특성에 관한 연구는 주로 함정이나 어선의 경우에 연구되어져 왔는데, 특히 소형어선의 경우 해난사고 대부분이 횡동요에 의한 전복사고이다. 이에 대해서 Tanaka et al.[4], Bass and Haddara[5]이 소형어선의 전복방지를 위해서 횡동요 연구를 수행하였다. Peter et al.[6]은 실험을 통해서 수중운동체의 동역학적 모델링에 대한 연구를 수행하였으며, 제어판의 횡동요 모멘트에 대한 연구와 함께 모멘트의 비선형 조종 계수에 대한 변수를 제공하였다. Arafat et al.[7] 은 AUV(Autonomous Underwater Vechicle)에 대한 동역학 모델 개발과 관련된 연구를 수행한바 있다.국내에서는 Na et al.[8]이 수중운동체의 항적 특성을 살펴보기 위하여 SUBOFF 모형에 대한 수치 시뮬레이션을 수행하였으며, Kim[9]은 전산유체해석을 통해 기저부를 갖는 축대칭

2 citations

Journal ArticleDOI
TL;DR: In this article , a numerical study of the contra-rotating propeller boss cap fins (CRPBCF) is carried out by using the STAR-CCM + software and the large eddy simulation (LES) model.

1 citations