https://scholarworks.bwise.kr/gachon/handle/2020.sw.gachon/482 2026-03-01T06:11:59Z 2026-03-01T06:11:59Z Samanta, A. Huang, W. Lee, Kyungjun He, X. Kumara, C. Qu, J. Ding, H. https://scholarworks.bwise.kr/gachon/handle/2020.sw.gachon/89360 2023-12-11T07:00:40Z 2023-08-01T00:00:00Z

Title: Effect of surface wetting on tribological behavior for laser textured steel using ionic liquid-based lubricants Authors: Samanta, A.; Huang, W.; Lee, Kyungjun; He, X.; Kumara, C.; Qu, J.; Ding, H. Abstract: In this study, the effect of surface wettability on the tribological performance is evaluated through a ball-on-flat reciprocating wear test. The substrate material, M2 tool steel, is laser processed and then functionalized with fluorocarbon and nitrile chemistry to achieve distinct oleophobicity and oleophilicity, respectively, but with a similar nanoscale surface texture. The poly-alpha-olefin (PAO) base oil is used as the baseline lubricant, and ammonium- and phosphonium-based oil-miscible ionic liquids (ILs) are used as additives. The interaction between the nanoscale textured steel surface and ionic liquid-based oils is investigated. A set of reciprocating wear tests are performed to identify the wear and frictional mechanisms of the tribosystem consisting of the surface-engineered, flat M2 tool steel specimen and a standard, surface-polished steel ball. Results show that the oleophobic flat surface results in a lower friction, while the oleophilic surface modification leads to a better wear protection to the flat surface. Ammonium-based IL provides the highest friction reduction, while the phosphonium-based IL provide an improved wear protection. Click here and insert your abstract text. © 2023 Society of Manufacturing Engineers (SME). Published by Elsevier Ltd. All rights reserved. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the Scientific Committee of the NAMRI/SME. © 2023 The Author(s)

2023-08-01T00:00:00Z 안현준 김용인 정재호 https://scholarworks.bwise.kr/gachon/handle/2020.sw.gachon/89320 2023-10-13T06:40:41Z 2023-10-01T00:00:00Z

Title: RANS 기반 CFD 활용 사류 펌프 내부 유동 및 공동 현상 수치해석적 분석 Authors: 안현준; 김용인; 정재호 Abstract: Computational fluid dynamics were widely used to analyze the hydrodynamic behavior of the mixed-flow pump, and reliability and accuracy were validated by comparing the results with the experimental data. In this study, complicated cavitation phenomena has been implemented by the RPE model. As a result, it has been found that the overall error was 6.8% through comparison with the performance curve of the analysis value and the experimental data. Recirculation occurred near the shroud at the impeller inlet when the flow rate was 6 m3/min. In addition it was found that non-uniform pressure drop occurred at the impeller outlet when the flow rate was 9 m3/min. Through vortex visualization technique, the onset position of the tip leakage vortex captured at the blade tip region of suction surface. By comparing with vortex structure and cavitation region, it was found that tip leakage vortex suppresses cavitation phenomenon at the blade tip region of suction surface.

2023-10-01T00:00:00Z 박성철 하광태 정재호 https://scholarworks.bwise.kr/gachon/handle/2020.sw.gachon/89319 2023-10-13T06:40:39Z 2023-10-01T00:00:00Z

Title: 난류모델에 따른 SMART BLADE 공력 특성 연구 Authors: 박성철; 하광태; 정재호 Abstract: This study presents an analysis of the aerodynamic performance characteristics of 20 m rotor blades for the NREL CART3 wind turbine within the SMART BLADES and SMART BLADES-2 projects. Three-dimensional Computational Fluid Dynamics (CFD) analysis was conducted to investigate the aerodynamic behavior. The Reynolds Averaged Navier-Stokes (RANS)-based turbulence model was utilized for numerical simulations, and the results were compared with Fraunhofer’s Blade Elementary Momentum Theory (BEMT) results. The aerodynamic performance characteristics of the rotor blades were evaluated using three turbulence models: Spalart Allmaras (S-A), standard k-ω, and Shear Stress Transform (SST) k-ω. The turbulence models demonstrated good agreement with the BEMT results at wind speeds below the rated power. However, under rated power wind speed conditions, the S-A and standard k-ω turbulence models exhibited an underprediction of aerodynamic performance. This discrepancy was attributed to an overestimation of the flow delamination point and recirculation region near the blade hub. Therefore, i t is r ecommended t o employ t he S S T k-ω turbulence model, which accurately captures turbulence phenomena both inside and outside the boundary layer, for rated power speed conditions.

2023-10-01T00:00:00Z 이준영 정현철 정재호 https://scholarworks.bwise.kr/gachon/handle/2020.sw.gachon/89314 2023-10-13T05:41:04Z 2023-09-01T00:00:00Z

Title: 수치해석 활용 대용량 풍력발전시스템 유지보수 시 타워 및 블레이드 후류에 따른 드론 블레이드 간섭 연구 Authors: 이준영; 정현철; 정재호 Abstract: The aim of this study is to develop guidelines for predicting interference between drones and wakes during non-destructive blade inspections in wind power systems. The wake generated by wind towers and blades can affect the stability of drone flights, necessitating the establishment of guidelines to ensure safe and efficient inspections. In order to predict the interference between drones and blades, environmental variables must be considered, including quantification of turbulence intensity in the wake generated by the tower and blades, as well as determining the appropriate distance between the drone and the tower/blades for flight stability. To achieve this, computational fluid dynamics (CFD) analysis was performed using cross-sectional geometries corresponding to the main wind turbine blade and tower span locations. Based on the CFD analysis results, a safe flight path for drones is proposed, which minimizes the risk of collision and interference with towers and blades during maintenance operations of wind power systems. Implementation of the proposed guidelines is expected to enhance the safety and efficiency of maintenance work.

2023-09-01T00:00:00Z