Bum-Suk Kim

Flow Characteristics of Cryogenic Butterfly Valve for LNG Carrier (Part 2 : Flow Characteristics under Cryogenic Condition)

Recently, butterfly valves are used as control valves for industrial process. However, there are not so many reports on cryogenic butterfly valves in spite of broad application in LNG storage station and LNG carriers. Present study is focused on the investigation of the detailed hydrodynamic and aerodynamic characteristics of cryogenic butterfly valves to contribute to the operation during the handling on LNG transportation system, and to the practical utilization in design of butterfly valves and actuators. The results show that large recirculation vortices in the region downstream of the valve are founded and the cavitation flows are intensively generated on the surface of valve disc at the relatively small opening angle. The aerodynamic characteristics, lift, drag and torque, acting on the valve disc are calculated. The pressure distribution and the pressure loss coefficient of the cryogenic butterfly valve show almost similar pattern with those of the butterfly valve which is used on the normal temperature.

A study on the design assessment of 50kW ocean current turbine using fluid structure interaction analysis

This research represents the results of performance prediction and structural safety evaluation of 50 KW ocean current turbine rotor assembly. Unsteady CFD simulation on the rotor assembly was performed to predict the performance of rotor assembly, and a cavitation model was applied with consideration of underwater operating conditions. Flow analysis result showed that the average power output was 47.34kW at an extreme flow velocity of 6 m/s and cavitation phenomena which is repeatedly occurred around the rotor assembly was also observed. The structural safety of the rotor assembly was evaluated by unidirectional FSI analysis. The analysis results showed that the minimum safety factor of the rotor assembly was 3.76. From the result, it was concluded that the rotor assembly had sufficient structural safety at an extreme operating condition.

Design of a 2MW Blade for Wind Turbine and Uni-Directional Fluid Structure Interaction Simulation

The purposes of this study are to evaluate the power performance through CFD analysis and structural integrity through uni-directional FSI analysis in aerodynamic design and structure design of wind turbine blade. The blade was designed to generate the power of 2MW under the rated wind speed of 11 m/s, consisting of NACA 6 series, DU series and FFA series airfoil. The inside section of the blade was designed into D-spar structure and circular stiffener was placed to reinforce the structural strength in the part of hub. CFD analysis with the application of transitional turbulence model was performed to evaluate the power performance of blade according to the change of TSR and 2.024MW resulted under the condition of rated wind speed. TSR of 9 produced the maximum power coefficient and in this case, Cp was 0.494. This study applied uni-directional FSI analysis for more precise evaluation of structural integrity of blade, and the results of fiber failure, inter fiber failure and eigenvalue buckling analysis were evaluated, respectively. For the evaluation, Puck`s failure criteria was applied and the result showed that fiber failure and inter fiber failure did not occur under every possible condition of the analysis. As a result, power performance and structural integrity of 2 MW blade designed in this study turned out to satisfy the initial design goals.

Basic Configuration Design and Performance Prediction of an 1 MW Wind Turbine Blade

In modem wind power system of large capacity above 1MW, horizontal axis wind turbine(HAWT) is a common type. And, the optimum design of wind turbine to guarantee excellent power performance and its reliability in structure and longevity is a key technology in wind Industry. In this study, mathematical expressions based upon the conventional BEMT(blade element momentum theory) applying to basic 1MW wind turbine blade configuration design. Power coefficient and related flow parameters, such as Prandtl`s tip loss coefficient, tangential and axial flow induction factors of the wind turbine analyzed systematically. X-FOIL was used to acquire lift and drag coefficients of the 2-D airfoils and we use Viterna-Corrigan formula to interpolate the aerodynamic characteristics in post-stall region. In order to predict the performance characteristics of the blade, a performance analysis carried out by BEMT method. As a results, axial and tangential flow factors, angle of attack, power coefficient investigated in this study.

Structural Design of Multi-Megawatt Wind Turbine Blade by Classical Lamination Theory

This research presents a method for the initial structural design of a multi-megawatt wind turbine blade. The structural data for a 2-MW blade were applied as the blade structural characteristic data of the reference blade. Tenkinds of blade models were newly designed by replacing the spar cap axial GRRP with a GFRP and CFRP These terms should be defined. at different orientations. The axial stiffness coefficients of the newly designed models were made equal to the coefficient of the reference blade. The required numbers of layers in each section of blades were calculated, and the lay-up designs were based on these numbers. Verification results showed that the design method that used the structural data of the reference blade was appropriate for the initial str uctural design of a wind turbine blade.

Software Development for the Performance Evaluation and Blade Design of a Pitch-Controlled HAWT based on BEMT

ABSTRACT The purpose of this study is to develop a software for the performance evaluation and blade design of a pitch-controlled HAWT using BEMT(Blade Element Momentum Theory) with Prandtl’s tip loss. The HERACLES V2.0 software consist of three major part ; basic blade design, aerodynamic coefficient mapping and performance calculation including stall or pitch control option. A 1MW wind turbine blade was designed at the rated wind speed(12m/s) composing five different airfoils such as FFA-W-301, DU91-W250, DU93-W-210, NACA 63418 and NACA 63415 from hub to tip. The mechanical power predicted by BEMT at the rated wind speed is about 1.27MW. Also, CFD analysis was performed to confirm the validity of the BEMT results. The comparison results show good agreement about the error of 6.5% in rated mechanical power. †† 1. 서 론 최근에 국제적으로 거론되고 있는 각종 환경관련 국제협약과 기후변화협약에 기초한 교토의정서의 채택으로 인해 환경문제의 심각성에 대한 관심이 상당히 높아지고 있다. 우리 정부도 이러한 상황에 대응하기 위해 신재생에너지에 대한 관심이 급격히 증가하고 있는 실정이며 그 중에서도 풍력에너지의 높은 가능성에 주목하고 있다. 현재 국내 요소설계 기술수준은 풍력발전용 터빈의 핵심요소기술 중의 하나인 로터 블레이드 설계 기술에 대한 명확한 설계기준이 없는 상황이며, 블레이드 설계 및 성능평가를 위해 BEMT 이론 및 다양한 손실 보정 모델을 적용한 Garrad Hassan 사의 GH-Bladed 등과 같은 국외 상용 소프트웨어에 의존하고 있다. 이러한 국내실정을 감안할 때, 국내에서도 블레이드 설계 및 성능평가* 한국해양대학교 해양에너지 전문인력양성사업단** (사)한국선급 에너지ㆍ산업기술센터*** 목포대학교 기계공학과 ****한국해양대학교 기계 ㆍ에너지시스템공학부† 교신저자, E-mail : lyh@hhu.ac.kr에 관한 명확한 기준 등이 수립될 필요가 있으며, 다양한 설계 이론과 성능예측 기법들에 대한 연구를 통해 독자적인 설계 및 성능평가 소프트웨어의 개발이 필요한 시점이다.

A Study on the Ultimate Load Assessment and the Performance Prediction of a Wind Turbine

Design life-time of a wind turbine is required to be at least 20 years. In the meantime, the wind turbine will experience a lot of load cases such as extreme loads and fatigue loads which will include several typhoons per year and extreme gusts with 50 years recurrence period as well as endless turbulence flow. Therefore, IEC61400-1 specifies design load cases to be considered in the wind turbine design and requires the wind turbine to withstand the load cases in various operational situations. This paper investigates the ultimate loads which the wind turbine will experience for 20 years and their characteristics based on the IEC61400-1 using an aero-elastic software, GH-Bladed. And the performance characteristics of a wind turbine such as electrical power generation and annual energy yield are also investigated.

A Study of Performance Estimate and Flow Analysis of the 500 kW Horizontal-Axis Wind Turbine by CFD

The purpose of this 3-D numerical simulation is to calculate and examine the complex 3-D stall phenomena on the rotor blade and wake distribution of the wind turbine. The flow characteristics of 500kW Horizontal Axis Wind Turbine (HAWT) are compared with the calculated 3-D stall phenomena and wake distribution. We used the CFX-TASCflow to predict flow and power characteristics of the wind turbine. The CFD results are somewhat consistent with the BEM (Blade Element Momentum) results. And, the rotational speed becomes faster, the 3-D stall region becomes smaller. Moreover, the pressure distribution on the pressure side that directly gets the incoming wind grows high as it goes toward the tip of the blade. The pressure distribution on the blade`s suction side tells us that the pressure becomes low in the leading edge of the airfoil as it moves from the hub to the tip. However, we are not able to precisely predict on the power coefficient of the rotor blade at the position of generating complex 3-D stall region.