• 대한기계학회논문집B
• /
• 제21권11호
• /
• pp.1449-1457
• /
• 1997

Since a non-nulling method of five-hole probes is valid only when the flow angle is within the calibrated angle range, it can not be used in a complex flow field. Full angle range pressure coefficient maps show that widely used nulling methods do not guarantee correct alignment of the probe with the flow direction in the unknown complex flow field. Zone decision method and features of zone map were studied by investigating the full angle range pressure coefficient maps. A reliable and efficient new nulling algorithm using zone decision by pressure ordering is proposed and verified. Since the zone decision method by pressure ordering can decide whether the flow is within the calibration angle range or not, it is useful in wide angle nonnulling methods, too.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
• /
• pp.193-199
• /
• 2000

The effects of Reynolds number on the non-nulling calibration of a cone-type five-hole probe in low-speed flows have been investigated at the Reynolds numbers of $2.04{\times}10^3,\;4.09{\times}10^3$, and $6.13{\times}10^3$. The calibration is conducted at the pitch and yaw angles in ranges between -35 degrees and 35 degrees with an angle interval of 5 degrees. The result shows that each calibration coefficient, in general, is a function of the pitch and yaw angles, so that the pre-existing calibration data in a nulling mode are not enough in accounting for the full non-nulling calibration characteristics. Due to the interference of the probe stem, the calibration coefficients have more Reynolds number sensitivity at positive pitch angles than at negative ones.

• 대한기계학회논문집B
• /
• 제26권1호
• /
• pp.27-38
• /
• 2002

The effects of Reynolds number on the non-nulling calibrations of a cone-type ave-type probe in low-speed flows have been investigated at Reynolds numbers of 2.04$\times$10$^3$, 4.09$\times$10$^3$and 6.13$\times$10$^3$. The calibration is conducted at the pitch and yaw angles in ranges between -35 degrees and 35 degrees with an angle interval of 5 degrees. In addition to the calibration coefficients, reduced pitch and yaw angles, static and total pressures, and velocity magnitude are obtained through a typical non-nulling reduction procedure. The result shows that each calibration coefficient, in general, is a function of both the pitch and yaw angles, so that the pre-existing calibration data in a nulling mode are not enough in accounting far the full non-nulling calibration characteristics. Due to interference of the probe stem, the calibration coefficient are more sensitive to Reynolds number at positive pitch angles than at negative ones. The calibration data reduced in this study may serve as a guide line in the estimation of uncertainty intervals resulted from the Reynolds number effects at low Reynolds numbers.

• Journal of Advanced Marine Engineering and Technology
• /
• 제20권2호
• /
• pp.116-116
• /
• 1996

This paper is concerned with a method for calibrating five-hole probes of both angle-tube and prismatic geometries to measure local total and static pressures and the magnitude and direction of the mean velocity vector. Descriptions of the calibration technique, the typical calibration data, and an accompanying discussion of the interpolation procedure are included. The flow properties are determined explicitly from measured probe pressures using calibration data. Flow angles are obtained within the deviation angle of 1.0 degree and dynamic pressures within 0.03 with 95% certainty. The variations in the calibration data due to Reynolds number are also discussed. For the range of Reynolds number employed, no effect was detected on the pitch, yaw and total pressure coefficients. However, the static pressure coefficient showed change to cause minor variations in the magnitude of the calculated velocity vector. To account for these variations, average correction factors need to be incorporated into the static pressure coefficient.

• Journal of Advanced Marine Engineering and Technology
• /
• 제20권2호
• /
• pp.48-56
• /
• 1996

This paper is concerned with a method for calibrating five-hole probes of both angle-tube and prismatic geometries to measure local total and static pressures and the magnitude and direction of the mean velocity vector. Descriptions of the calibration technique, the typical calibration data, and an accompanying discussion of the interpolation procedure are included. The flow properties are determined explicitly from measured probe pressures using calibration data. Flow angles are obtained within the deviation angle of 1.0 degree and dynamic pressures within 0.03 with 95% certainty. The variations in the calibration data due to Reynolds number are also discussed. For the range of Reynolds number employed, no effect was detected on the pitch, yaw abd total pressure coefficients. However, the static pressure coefficient showed change to cause minor variations in the magnitude of the calculated velocity vector. To account for these variations, average correction factors need to be incorporated into the static pressure coefficient.

• 동력기계공학회지
• /
• 제19권1호
• /
• pp.19-23
• /
• 2015

The swirling flow fields of a gun-type gas burner(GTGB) without a combustion chamber were measured by a straight-type five-hole pressure probe(FHPP) under the cold flow condition. The three kinds of velocity components and the static pressure were calculated by using a non-nulling calibration method covering the velocity reduction performance of the effective flow attack angle of ${\pm}80^{\circ}$. As a result, the velocity and static pressure measured by a FHPP comparatively shows the better performance on the swirling flow of a GTGB than those measured by X-probe.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
• /
• pp.26-30
• /
• 1996

This paper proposes a novel method to reduce the torque ripple due to the non-ideality of the current sensing parts in vector-controlled inverter-fed PMSM(Permanent Magnet Synchronous Motor) drive systems. The motor output torque equations are derived in terms of their offset voltages and different voltage transducing gains. And the effects of phase current errors on motor torque are analyzed for both salient PMSM and non-salient PMSM. The proposed method can eliminate the torque ripple by nulling the offset voltages and setting the voltage transducing gains to the same value. To verify the proposed method, digital simulations are carried out for non-salient PMSM.

• 한국지구물리탐사학회:학술대회논문집
• /
• 한국지구물리탐사학회 2006년도 공동학술대회 논문집
• /
• pp.9-14
• /
• 2006

자기쌍극자 모멘트의 깊이, 방향, 크기 등에 관한 평가는 자기탐사자료로부터 폭발물과 기타 자성체를 구분하는데 유용한 정보를 제공한다. 이러한 평가는 지질학적 잡음, 자기분산체, 주변 쌍극자기장 중첩 등의 이유로 방해를 받을 수 있다. 임의의 극성을 갖는 단일 혹은 다중 쌍극자 이상체의 효과적 계산을 위하여, 역산내부 필터 및 배경 자기장의 구배 평가를 포함하는 개선된 역산법을 개발하였다. 관측값들은 보간하여 격자화하였으며, 관측점으로부터 가장 가까운 계산점만을 사용하도록 표시하였다. 이러한 자료에 역산내부 필터를 적용하기 위하여는 빈간격 필터가 필요하다. 게다가 상당히 빈 곳이 많은 자료나 조사지 가장자리 및 구석 부분 자료들을 처리하기 위해서는 역산내부 필터를 수정하여야 한다. 이러한 목적으로 가장자리에 적용가능한 빈간격 구배제거 필터를 고안하고 시험하였다. 한국 속초의 청초호와 미국 매릴랜드의 육군 애벌딘 무기시험장에서 기록한 자기탐사자료에 적용한 결과를 소개한다.

• 대한기계학회논문집B
• /
• 제38권12호
• /
• pp.991-997
• /
• 2014

이 연구는 Gun식 가스버너의 스월유동장을 연소실과 화염이 없는 상태에서 직선형 5공압력프로브의 측정을 통해 고찰하였다. 직선형 5공압력프로브에 의한 속도 및 정압성분들은 넌널링 교정방법에 의해 연산하였으며, X형 열선프로브와 전산유체역학의 해석에 의한 결과들과 비교하였다. 결과적으로 Gun식 가스버너의 중심부에서 스월유동장에 대해 5공압력프로브에 의한 속도 및 정압의 측정값들은 비교적 X형 열선프로브에 의한 경우보다는 좋은 성능을 보였으나 전산유체역학의 해석에 의한 경우보다는 다소 미흡한 결과를 보였다.

• 대한기계학회논문집B
• /
• 제21권11호
• /
• pp.1437-1448
• /
• 1997

Pressures of a five-hole probe were measured for a full range of yaw and pitch angles and complete pressure coefficient maps were obtained. Based on these maps, various features of five-hole probe pressures were revealed and new five-hole probe calibration coefficients were devised. The new calibration coefficients show non-diverging characteristics for any flow direction and one-to-one correspondence for a wide range of flow angles. These calibration coefficients expand the valid flow angle range of five-hole probe calibration by .+-.10 degrees and complement a critical defect of five-hole probe zone-division calibration method which has not been known yet. Moreover new non-diverging calibration coefficients have advantages in nulling methods, too.