• 제목/요약/키워드: loss angle

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The Iron loss Estimation of IPMSM According to Current Phase Angle

  • Cho, Gyu-Won;Kim, Dong-Yeong;Kim, Gyu-Tak
    • Journal of Electrical Engineering and Technology
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    • 제8권6호
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    • pp.1345-1351
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    • 2013
  • Variable iron loss as function of current phase angle of Interior Permanent Magnet Synchronous Motor(IPMSM) was calculated through Curve Fitting Method(CFM). Also, a magnetic flux density distribution of iron core according to current phase angle was analyzed, and an iron loss calculation was performed including harmonic distortion. The experiment was performed by production of non-magnetizing model for the separation of mechanical loss, and the iron loss was calculated by the measurement of input using power analyzer and output power using dynamometer. Some error was generated between experimental results and calculation value, but an iron loss diminution according to current phase angle followed a same pattern. So, errors were generated by measurement, vibration, noise, harmonic distortion loss, etc.

입사각이 고선회 터빈 동익 하류에서의 3차원 유동 및 압력손실에 미치는 영향 (Effects of Incidence Angle on the Three-Dimensional Flow and Aerodynamic Loss Downstream of a High-Turning Turbine Rotor Blade)

  • 채병주;이상우
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2007년도 춘계학술대회B
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    • pp.2591-2596
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    • 2007
  • The effect of incidence angle on the three-dimensional flow and aerodynamic loss in the downstream region of a high-turning turbine rotor blade has been investigated with a straight miniature five-hole probe. The incidence angle is changed to be +10, +5, 0, -10, -20, -30 and -40 degrees. The results show that the positive incidence reinforces the three-dimensional vortical flows within the turbine passage including the passage vortex, but the negative incidence weaken them significantly. A small increment in the positive incidence angle results in a remarkable aerodynamic loss increase, while increasing the incidence angle in the negative range leads to a very small change in the aerodynamic loss.

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산업용 조정 피치형 축류송풍기의 성능예측에 관한 연구 (Study on Performance Prediction of Industrial Axial Flow Fan with Adjustable Pitch Blades)

  • 구재인;김창수;정진택;김광호
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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    • pp.30-34
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    • 2001
  • In the present study, we studied the method of predicting the on-design and on-design point performance of axial flow fan with adjustable pitch blades. With the change of stagger angle of axial flow fan with adjustable pitch blade, flow rate and pressure can be changed. Because of this merit adjustable pitch fans are used in many industrial facility. When changing stagger angle or estimating the performance at a wide range of off-design condition, incidence angle changes greatly as the flow rate changes. Therefore, the deviation angle at the blade exit is estimated by the correlation considering the effects of blade design, incidence angle variation. In the loss model, we used known pressure loss model for blade boundary layer and wake, secondary flow, endwall boundary layer and tip leakage flow. The results of modified deviation angle model and experiment were compared for the usefulness of the modified model.

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축류터빈에서 끝간격 유동에 의한 편향각과 압력손실의 모형 (Modeling of Deviation Angle and Pressure Loss Due to Rotor Tip Leakage Flow Effects in Axial Turbines)

  • 윤의수;박부룡;정명균
    • 대한기계학회논문집B
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    • 제22권11호
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    • pp.1591-1602
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    • 1998
  • Simple spanwise distribution models of deviation angle and pressure loss coefficient due to the tip leakage flow are formulated for use in association with the streamline curvature method as a flow analysis. Combining these new models with the previous deviation and loss models due to secondary flow, a robust streamline curvature method is established for flow analysis of single-stage, subsonic axial turbines with wide ranges of turning angle, aspect ratio and blading type. At the exit from rotor rows, the flow variables are mixed radially according to a spanwise transport equation. The proposed streamline curvature method is tested against a forced vortex type turbine as well as a free vortex type one. The results show that the spanwise variations of flow angle, axial velocity and loss coefficients at rotor exit are predicted with good accuracy, being comparable to a steady three-dimensional Navier-Stokes analysis. This simple and fast flow analysis is found to be very useful for the turbine design at the initial design phase.

무지외반증 수술에서 제 2족지의 외반 정도가 무지 외반각 교정소실에 미치는 영향 (The Effect of Second Toe Valgus on Correction Loss of Hallux Valgus Angle in Surgical Treatment)

  • 강석웅;송무호;김영준;오영광;유성호
    • 대한족부족관절학회지
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    • 제21권4호
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    • pp.135-138
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    • 2017
  • Purpose: The purpose of this study is to determine the correlation between the correction loss of hallux valgus angle and the severity of valgus angle of the second toe. Materials and Methods: We selected 312 cases from 268 surgical patients with hallux valgus deformity receiving distal chevron osteotomy. For a radiological evaluation, we analyzed the changes in the hallux valgus angles, first to second intermetatarsal angles, and valgus angle of the second toe post index operations. All patients were women; the mean age was 46 years. The mean follow-up period was 17 months. Results: The mean hallux valgus angle was $33.6^{\circ}$ preoperatively (range, $25.7^{\circ}{\sim}44.8^{\circ}$), $13.1^{\circ}$ (range, $8.4^{\circ}{\sim}16.4^{\circ}$) after 4 weeks of postoperative period, and $17.1^{\circ}$ (range, $9.4^{\circ}{\sim}28.5^{\circ}$) at their final follow-up. The mean valgus angle of the second toe was $8.4^{\circ}$ preoperatively (range, $2.0^{\circ}{\sim}25.8^{\circ}$) and $8.3^{\circ}$ (range, $1.7^{\circ}{\sim}24.9^{\circ}$) at the final follow-up. Preoperatively, there was a positive correlation between the valgus angle of the second toe and hallux valgus angle (r=0.747, p=0.001). The correction loss of hallux valgus angle had a significant correlation with the severity of valgus angle of the second toe (r=0.802, p=0.001). Conclusion: The existence of the second toe valgus deformity may present itself as a cause of correction loss of hallux valgus angle. The preoperative measurement of the second toe valgus angle may be a good predictor of correction loss; therefore, thorough preoperative warning on the possibility of correction loss should be conducted to maximize patient satisfaction after the procedure.

극저온 버터플라이 밸브의 유속에 따른 캐비테이션 발생 예측 (Prediction of Cavitation Occurrence in a Cryogenic Butterfly Valve by Flow Velocity)

  • 김성동;김범석;최영도;이영호
    • Journal of Advanced Marine Engineering and Technology
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    • 제32권6호
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    • pp.923-930
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    • 2008
  • The butterfly valve is widely used in the industrial field as an on-off or a flow control valve. When the butterfly valve is used as a flow control valve. cavitation sometimes occurs in the range of high flow rate because of the small valve opening. Therefore. the pressure loss and the cavitation characteristics are investigated by use of a commercial CFD code. The results show that the possibility of cavitation occurrence in the cryogenic butterfly valve is very high in the case of valve opening angle below 10 degree and incident velocity over 6m/s. By increasing the inlet velocity at 10 degree of valve opening angle. the value of loss coefficient increased. However. by increasing the inlet velocity at 50 degree of valve opening angle. the value of loss coefficient decreased.

익렬 통로 내의 2차유동 및 손실에 관한 실험 연구 (An experimental study on the secondary flow and losses in turbine cascades)

  • 정양범;신영호;김상현
    • 대한기계학회논문집B
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    • 제22권1호
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    • pp.12-24
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    • 1998
  • The paper presents the mechanism of secondary flows and the associated total pressure losses occurring in turbine cascades with turning angle of about 127 and 77 degree. Velocity and pressure measurements are taken in seven traverse planes through the cascade passage using a prism type five hole probe. Oil-film flow visualization is also conducted on blade and endwall surfaces. The characteristics of the limiting streamlines show that the three dimensional separation is an important flow feature of endwall and blade surfaces. The larger turning results in much stronger contribution of the secondary flows to the loss developing mechanism. A large part of the endwall loss region at downstream pressure side is found to be very thin when compared to that of the cascade inlet and suction side endwall. Evolution of overall loss starts quite early within the cascade and the rate of the loss growth is much larger in the blade of large turning angle than in the blade of small turning angle.

손실감도를 이용한 계통손실 최적화에 대하여 (On The Optimal Generation Using The Loss Sensitivities Derived by Angle Reference Transposition)

  • 양성덕;이상중
    • 조명전기설비학회논문지
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    • 제19권1호
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    • pp.59-63
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    • 2005
  • 전력계통을 효율적으로 운용하려면 관련량을 정확하고 신속히 계산하는 좋은 알고리즘이 필요하다. 최근 IEEE Transaction on Power System에 위상각 이동을 이용한 손실 최적화 알고리즘이 발표되었다. 동일한 손실최적화 문제를 본 논문에서는 Standard method of Lagrange Multiplier 기법을 적용하여 해석하였으며, 그 결과 저자들은 두 가지 방법이 수학적으로 동일함을 증명하였다.

챔퍼가 적용된 타공판의 압력 강하 특성에 대한 연구 (Effects of Chamfered Perforated Plate on Pressure Loss Characteristics)

  • 유경식;이현규;조진수
    • 한국항공우주학회지
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    • 제47권11호
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    • pp.779-786
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    • 2019
  • 본 연구에서 챔퍼가 적용된 타공판의 압력 강하특성에 대한 연구를 진행하였다. 타공판 홀의 입구와 출구에 각각 챔퍼를 적용하였다. 타공판의 패턴이 압력 강하특성에 미치는 영향에 대하여 관찰하였다. 타공판 홀의 입구와 출구에 챔퍼 각도를 변경해 가며 압력 강하 특성을 비교하였다. 레이놀즈 수에 따른 강하특성을 확인하였다. 타공판 홀 입구에 적용된 챔퍼의 각도가 증가함에 따라 압력강하계수가 감소하였지만 특정 각도 이후에서 압력강하계수가 증가하는 것을 확인하였다. 타공판홀 출구에 적용된 챔퍼 형상의 경우 특정 각도와는 상관없이 압력 강하계수가 증가하였다. 동일한 개공률의 타공판에서 삼각 및 사각 패턴에 따른 압력 강하특성은 동일하였다. 본 연구에서 설정한 레이놀즈 수 범위 내에서 압력 강하특성에 대한 레이놀즈 수의 영향은 없는 것으로 확인하였다.

이중판의 차음손실 I (Sound Transmission Loss of Double Panels(I) : A Double Wall with Air Cavity)

  • 강현주;김현실;김재승;김상렬
    • 소음진동
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    • 제7권6호
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    • pp.945-952
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    • 1997
  • This paper shows the feasibility of the suggestion that the angle distribution of incident sound to panels might be gaussian, instead of the conventional uniform distribution in the analysis of transmission loss of panels. To prove the suggestion, the problems with the diffuse sound field in a reverberation room are examined by case studies and the comparision of the prediction with the measurement of sound transmission loss of walls are performed. The results of the comparision show good agreement between the two values.

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