선박용 터보차져 원심압축기의 성능향상 개발

오종식(JongSik Oh),오국섭(KoonSup Oh),유광택(KwangTaek Yoo) 한국유체기계학회 1999 유체기계 연구개발 발표회 논문집 Vol.- No.-

선박용 디젤엔진에 장착되어 사용되는 기존의 터보차져 성능을 개량하기 위하여 압축기만의 수정개발을 수행한 결과를 요약하면 다음과 같다.<br/> (1) 터빈과의 싸이클 matching 작업을 통하여 기존의 압축기 성능에 비하여 7% 증가된 회전수와 8% 증가된 입구 공기유량으로 상향 조정되면서 효율의 큰 저하 없이 全압력비도 3.5 수준으로 증가되도록 설계점이 성공적으로 확정되었다.<br/> (2) 기존의 압축기 케이싱과 스크롤을 대부분 그대로 사용한다는 기하학적 제한조건하에서 3차원 공력설계가 성공적으로 수행되었고, 설계된 임펠러는 3차원 압축성 난류 수치유동 해석 과정을 통해 구체적인 내부 유동과 임펠러의 overall 성능을 확인하였다.<br/> (3) 터보차져 전용 시험리그에서 시제품을 성능 시험한 결과, 전반적인 압축기의 성능곡선을 성공적으로 도출하였다. 대체적으로 전체 회전수별로 실험결과로 얻은 全압력비는 설계 예측치와 매우 잘 일치하는 모습을 볼 수 있었고, 단열효율의 경우, 실험치와 예측치가 서로 잘 일치하고 있었다. 설계의도대로 설계점에서의 압력비 상승과 유량의 증가 등은 만족스럽게 달성된 것으로 판단된다.<br/> (4) 베인디퓨져의 제작문제로 인하여 설계회전수에서의 surge & choke margin이 설계의도와는 달리 좋지 않은 상태이다. 이는 본래 설계대로 베인디퓨져를 재제작하고 설치각의 크기를 조절함으로써 앞으로 진행될 추가시험에서 보완할 예정이다. Upgrade development of a high pressure ratio centrifugal compressor in marine engine turbochargers is presented. A new matched operating point at increased speed of rotation was determined through system cycle analysis using the exisitng test data of turbine performance. Under some severe restrictions for geometric parameters, the state-of-the-art methods of both aerodynamic design and CFD analysis were applied, in which only an impeller, a vaned diffuser and some part of casing wall were modified. Prototype hardware was fabricated and assembled for system performance tests. Excellent performance in pressure ratio and efficiency was obtained over whole speed region. Reduced surge and choke margin was, however, observed at design speed of rotation.

원심압축기용 베인디퓨져의 탈설계점 성능연구 - 제2부 : 솔리디티가 작은 익렬디퓨져 -

오종식(JongSik Oh),이헌석(HeonSeok Lee) 한국유체기계학회 2001 유체기계 연구개발 발표회 논문집 Vol.- No.-

As the second part of the author’s study, off-design behavior of the design and performance parameters in the low-solidity cascade diffuser in a centrifugal compressor is investigated. The experimental flange-to-flange compressor map serves the validity of application of the present CFD work to the detailed investigation of the low-solidity cascade diffuser. Some meanline design and performance parameters as well as three-dimensional internal secondary flow fields are studied when the flow rate is changed from deep choke to stall.

다단 원심펌프 임펠러의 개량 수력설계

오종식(JongSik Oh),김동수(DongSoo Kim) 한국유체기계학회 2001 유체기계 연구개발 발표회 논문집 Vol.- No.-

For two kinds of the multi-stage centrifugal pump with diffuser vanes and return channel vanes, the meanline performance prediction is applied to get information of hydraulic performance at each internal flow station, because only flange-to-flange test curves are available. As a first step of redesign for higher efficiency, the impeller geometry is numerically investigated in the present study. Quasi-3D inviscid loading distributions are obtained, for the two impellers, using the state-of-the-art method of impeller 3D design, which provides a guide to optimal redesign. Full 3D turbulent flow fields are thereafter analyzed, using the specialized CFD code, to confirm the redesign results. The inherent limitation of the traditional graphic method of impeller design, which most of domestic pump manufacturers are now employing, is found.

차세대 신개념 터보블로워의 세계최초 상품화 개발

오종식(JongSik Oh),이헌석(HeonSeok Lee) 한국유체기계학회 2002 유체기계 연구개발 발표회 논문집 Vol.- No.-

In the paper, the development of high-speed industrial turbo blowers with foil air bearings is presented as a first successful commercialization in the world. Their target market is various from wastewater treatment to cement factory processes which require compressed air ranging between 0.6 and 0.8 bar gauge. Employing the state-of-the-art technology of the high-speed BLDC motors, the bump-type foil air bearings and the high-efficient turbo impellers/diffusers, so much compact, efficient and silent blower machines of a single stage are now available in the market, aiming to replace the existing inefficient, bulky and noisy ones, such as roots blowers. The first production lines are established for 25, 75 and 150 hp class blowers. Rotational speeds from about 20,000 to 80,000 rpm are realized directly from the high-speed BLDC motors without any gear boxes, and no lubrication oil is required. A brief introduction of design, manufacture and test results is presented for mechanical, electrical and aerodynamic performance.

분산발전용 75㎾ 급 마이크로터빈의 시제개발 - 설계 / 제작 및 자력운전 시험 -

오종식(JongSik Oh),이헌석(HeonSeok Lee) 한국유체기계학회 2002 유체기계 연구개발 발표회 논문집 Vol.- No.-

In the paper, the prototype development of a 75㎾ class microturbine for the distributed generation market is partly presented which has continued with the government funding. In the introduction, an overview of the development of microturbines in the world is presented. A series of development procedures are shown with design, manufacture and self-sustaining tests. During the first year, aerodynamic and structural design/analysis, mechanical design are performed for the compressor, the turbine and the combustor. A premixed lean bum combustor technology is used for the low emission requirements. Foil air bearings and high-speed motors are employed for higher reliability. The self-sustaining conditions have been successfully achieved with the prototype manufactured engine as a preceding operation.

BLDC 전동기와 공기포일베어링을 이용한 고효율 터보블로워

오종식(JongSik Oh),이헌석(HeonSeok Lee) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-

High-efficiency turboblowers in the next generation have been successfully developed and commercialized first in the world, using the high-speed BLDC motors and the foil air bearings. About 20-35% savings in electricity consumption in the field are found in comparison with the conventional roots rotary blowers and the integral gear-driven turboblowers. Current TB75 and TB150 products are replacing the existing blowers in the worldwide market.

원심압축기의 임펠러의 Blockage와 Slip 특성에 관한 수치연구

오종식(JongSik Oh) 한국유체기계학회 2000 유체기계 연구개발 발표회 논문집 Vol.- No.-

As the second part of the author's study, the aerodynamic blockage and the slip factor of 8 centrifugal compressor impellers are investigated, when the flow rate is changed from numerical stall to choke, using three-dimensional Navier-Stokes analysis results. Based on all the exit blockage distributions, an improved model equation with two adjusting coefficients is developed for the use in design processes with the agile engineering purpose. A popular expression of constant slip factors, the Wiesner's equation, cannot be applied in design processes when more accurate prediction is strongly required at design and off-design points. Slip factor variation is found to be also influenced by the blade loadings at midspan. When the flow rate is changed, a pattern of the slip factor variations is assumed to be a simple form which can be explained using midspan blade loading distributions.

압력보정법을 이용한 8개의 원심압축기 임펠러 CFD의 적용 연구

오종식(JongSik Oh),노수혁(SooHyuk Ro),현용익(YongIk Hyun) 한국유체기계학회 2000 유체기계 연구개발 발표회 논문집 Vol.- No.-

Two representative finite volume methods, i.e., the time marching method and the pressure correction method, were applied to 8 centrifugal compressor impeller flows, with low to very high level of pressure ratio, among which 7 impellers' experimental performance is given in the open literature. The present study is focused on the prediction differences from both methods, developed by the authors, in the pressure correction method's point of view. In all cases, the time marching method gives a satifactory solution, but the pressure correction method does not. Up to about 18% less level of total-to-total pressure ratio is predicted by the pressure correction method as the level of the impeller pressure ratio increases up to about 10. The drop of total pressure ratio is caused by the underestimation of static pressure rise which seems to be attributed to inappropriate linearization and discretization of the pressure/density coupling terms in the pressure correction equation.

원심압축기용 베인디퓨져의 탈설계점 성능연구 - 제1부 : 채널디퓨져 -

오종식(JongSik Oh),현용익(YongIk Hyun) 한국유체기계학회 2001 유체기계 연구개발 발표회 논문집 Vol.- No.-

Experimental and numerical investigations of the off-design performance of a simple channel-wedge diffuser in a small centrifugal compressor are presented. Surge and choke conditions as well as design point are considered using somewhat limited range of experimental data and also supplementary 3D CFD results. Some critical meanline design parameters’ behavior is investigated numerically, to render the basis for improved modelings in the meanline performance prediction.

원심 압축기의 CFD를 위한 대표적인 Bench Mark

오종식(JongSik Oh) 한국유체기계학회 1999 유체기계 연구개발 발표회 논문집 Vol.- No.-

The importance of CFD work in the process of turbomachinery development has been continuously growing. It is therefore necessary to have some bench marks for validation purposes when any CFD codes are to be developed. In the present study, some public information on centrifugal compressor test results is collected to render useful data for the developers.