• Wind and Structures
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• 제18권2호
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• pp.195-213
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• 2014

Recently, the horizontal axis rotor performance optimizer (HARP_Opt) tool was developed in the National Renewable Energy Laboratory, USA. This innovative tool is becoming more popular in the wind turbine industry and in the field of academic research. HARP_Optwas developed on the basis of two fundamental modules, namely, WT_Perf, a performance evaluator computer code using the blade element momentum theory; and a genetic algorithm module, which is used as an optimizer. A pattern search algorithm was more recently incorporated to enhance the optimization capability, especially the calculation time and consistency of the solutions. The blade optimization is an aspect that is highly dependent on experience and requires significant consideration on rotor control strategies, wind data, and generator type. In this study, the effects of rotor control strategies including fixed speed and fixed pitch, variable speed and fixed pitch, fixed speed and variable pitch, and variable speed and variable pitch algorithms on optimal blade shapes and rotor performance are investigated using optimized blade designs. The effects of environmental wind data and the objective functions used for optimization are also quantitatively evaluated using the HARP_Opt tool. Performance indices such as annual energy production, thrust, torque, and roof-flap moment forces are compared.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.61.2-61.2
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• 2011

The spanwise aerodynamic loads of the wind turbine blade are investigated numerically. The blade shape such as twist and chord length along the blade span is obtained from the procedure of aerodynamically optimal design. The rated tip speed ratio and the rated wind velocity are set to 7 and 12m/s respectively. The BEM method is applied to obtain both the aerodynamic performance of the wind turbine (Fig.1) and the spanwise aerodynamic loads along the blade span including Prandtl's tip loss factor. The maximum running power coefficient is occurred around 90% radial position from hub (Fig.2). The distributed aerodynamic loads along the blade span can be used for structure analysis.

• 한국해양공학회지
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• 제29권5호
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• pp.366-372
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• 2015

Ocean energy is one of the most promising renewable energy resources. In particular, South Korea is one of the countries where it is economically and technically feasible to develop tidal current power plants to use tidal current energy. In this study, based on the design code for HARP_Opt (Horizontal axis rotor performance optimizer) developed by NREL (National Renewable Energy Laboratory) in the United States, and applying the BEMT (Blade element momentum theory) and GA (Genetic algorithm), the optimal shape design and performance evaluation of the horizontal axis rotor for a 200-kW-class tidal current turbine were performed using different numbers of blades (two or three) and a pitch control method (variable pitch or fixed pitch). As a result, the VSFP (Variable Speed Fixed Pitch) turbine with three blades showed the best performance. However, the performances of four different cases did not show significant differences. Hence, it is necessary when selecting the final design to consider the structural integrity related to the fatigue, along with the economic feasibility of manufacturing the blades.

• 대한기계학회논문집A
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• 제29권7호
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• pp.1013-1021
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• 2005

In this paper, we developed an automatic design optimization system for parametric shape optimization of cooling passages inside axial turbine blades. A parallel three-dimensional thermoelasticity finite element analysis code from an open source system was used to perform automatic thermal and stress analysis of different blade configuration. The developed code was connected to an evolutionary optimizer and built in a design optimization system. Using the optimization system, 279 feasible and optimal solutions were searched. It is provided not only one best solution of the searched solutions, but also information of variation structure and correlation of the 279 solutions in function, variable, and real design spaces. To explore design information, it is proposed a new interpretation approach based on evolutionary clustering and principal component analysis. The interpretation approach might be applicable to the increasing demands in the general area of design optimization.

• 한국유체기계학회 논문집
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• 제2권1호
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• pp.96-102
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• 1999

Cross flow fans are used in various applications, especially in industrial ventilation applications and in room air conditioners, due to their superior performance characteristics. Unlike radial and/or axial fans, the design of cross flow fans have been mostly based on earlier experiences and experiments. In the present study, numerical computations of flow fields through a cross flow fan used in room air conditioner are performed to investigate the detailed flow fields and to study the effect of the blade shape on performance curves to aid better design of the fan. Despite some discrepancies between the two results, it is seen from the present study that the computational results agree quite well with the qualitative experimental results. It is also shown from the present study that by having a different shape of blade, it is possible to achieve about $15\%$ increase in flow rates. The stimulating results of the present study can be used in the design of high performance cross flow fans with the use of optimal design algorithm and experimental verifications.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.645-650
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• 2002

In this paper, new concept, low noise axial fan was developed. The fan was designed to operate at high-pressure condition inside the refrigerator. This fan - we call it Alpha fan - has small turbo blades at trailing edge of axial fan. These turbo blades make alpha fan operate at high pressure and low noise condition. In order to find out the optimal value of design parameters, 6-sigma method was used. The design parameters are ratio between inner and outer diameter, Height, Install angle and Install position of turbo blade. Optimal value of turbo blade was found out and the noise generated from this fan is reduced about 3dB(A).

• 한국유체기계학회 논문집
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• 제19권2호
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• pp.21-26
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• 2016

The objective of present study is to assess the performance of the first stage compressor in a total 3-stage 5000 HP-level turbo compressor. CFD commercial code, CFX has been used to predict three-dimensional flow characteristics inside of the impeller. Shear Stress Transport (SST) model has been used to simulate turbulent flows through Reynolds-averaged Navier-Stokes (RANS) equations. Grid dependency has been also checked to get optimal grid distribution. Numerical results have been compared with the experimental test results to elucidate performance characteristics of the present compressor. In addition, flow characteristics of the impeller only have been studied for various blade configurations. Angular offset in leading edge of the blade has been selected for the optimal blade design. Performance characteristics in region of low mass flow rate and high pressure ratio between the impeller entrance and exit have been investigated for the selection of optimal blade design. Also, flow instability such as stall phenomena has been studied and anti-stall characteristics have been checked for various blade configurations in the operational window.

• 한국항공우주학회지
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• 제41권3호
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• pp.173-184
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• 2013

본 연구에서는 프로펠러나 헬리콥터 로터와 같은 회전체의 공력 최적 설계를 위한 다단 최적 설계 프레임워크를 제안한다. 이 프레임워크는 플랜폼 설계와 단면의 형상 설계를 반복적으로 수행하는 설계 전략을 통해 회전체의 공력 성능 향상을 목표로 한다. 플랜폼 설계의 단계에서는 유전 알고리즘과 2차원 CFD 데이터베이스 기반의 깃 요소 모멘텀 이론을 이용하여 빠른 시간에 회전체의 공력 특성을 평가하여 최적점을 탐색하였다. 플랜폼 설계 후 단면에 유입되는 유동 조건을 예측하여 단면 형상 최적 설계를 수행하였다. 설계 과정에서 보다 면밀하게 유동 특성이 분석될 수 있도록 2차원 N-S 해석자와 민감도 기반의 최적화 알고리즘을 통해 최적해를 탐색하였다. 단면 형상이 설계된 후에는 최적의 유동 조건을 산출할 수 있도록 플랜폼 설계를 반복적으로 수행하였다. 본 프레임워크를 1kW급 전기추진용 항공기 프로펠러 설계에 적용하여 그 유효성을 3차원 N-S 해석과 풍동 실험을 통해 검증하였다. 설계 후, 풍동 실험 결과를 기준으로 약 5%의 프로펠러 효율 증가를 얻을 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.420-423
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• 2008

This present work is to find optimum design of a NACA65 axial fan blade with weighted average surrogate model. The numerical analysis by Reynolds-average Navier-Stokes equations with shear stress turbulence(SST) is discretized by finite volume approximations and solved on hexahedral grids for flow analysis. The blade aerodynamic shape is modified by six design variables for the optimization. The blade profile as well as stacking line is modified to enhance blade total efficiency. Six design variables, airfoil maximum camber, maximum camber location, leading edge radius, trailing edge radius, lean angle at 50% span and lean angle at 100% span, are selected for blade profile to enhance the total efficiency. The PBA model which is basically weighted average of the basis surrogates is used to find the optimal design in the design space from the constructed response surface model for the objective function. By the optimization, the total efficiency is increased by 1.4%.

• 한국산학기술학회논문지
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• 제18권12호
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• pp.9-16
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• 2017

본 논문에서는 풍력 발전기 블레이드 공력 설계 프로세스를 정립하고, 최적화 설계 전략을 제시 하였으며, 공력 설계 진행시에 반드시 검토 필요한 제약 조건들에 대해서 정리 하였다. 이를 토대로 하여 연구 목적뿐 아니라, 블레이드 설계자가 실제 업무에 쉽게 적용 가능하고, 초기 개념설계 단계부터 최종 3차원 형상 상세 설계 단계까지 통합적으로 수행이 가능한 BEMT 기반의 공력 설계 프로그램을 개발하였다. 개발된 프로그램 AeroDA는 개념 설계 모듈, 기본 설계 모듈, 최적 TSR 도출 모듈, 국부 형상 최적화 모듈, 성능 해석 모듈, 설계 검증 모듈 및 3차원 형상생성 모듈로 구성이 된다. 개발된 프로그램을 활용하여 NREL에서 공개 배포한 5MW 블레이드를 기반으로하여 하중저감을 위한 개선 설계를 진행하여 본 프로그램이 최적화 설계에 유용하게 사용 가능함을 확인 하였다. 또한 10kW 블레이드 공력 설계 및 터빈 상세 성능 해석을 진행하고, 이를 상용 전문 프로그램 DNV GL Bladed 결과와 비교하여 정확도를 검증하였다.