• Title, Summary, Keyword: 피토관

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Development of the Pilot-Tube to Measure Flight Altitude and Velocity (비행체 고도 및 속도계측용 Pilot-Tube 연구)

  • 최진철;이기권;박찬우
    • Journal of the Korean Society of Propulsion Engineers
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    • v.5 no.3
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    • pp.19-24
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    • 2001
  • The Pilot-Tube is the device that measures velocity and altitude of high speed vehicle. Accurate measurements of speed and altitude are essential to the safe and efficient operation of aircraft. For the purpose of determining optimal design parameters of Pilot-Tube such as nose inlet configuration, nose shape, static hole configuration, and static hole location, subsonic flow field was calculated numerically and analyzed. A Pilot-Tube was manufactured based on numerical flow field analysis, and pressure and air velocity was measured experimentally in the wind tunnel. As a result manufacturing and design technologies of the Pilot-Tube were acquired to make flight-device.

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Investigation on the Effective Calibration of Annubar (다점식 피토관의 효율적인 교정에 대한 연구)

  • Choi Yong-Moon;Choi Hae-Man;Choi Ji-Chul;Hong Kyung-Ki;Han Sang-Woo;Kim Woong-Sun;Chun Se-Jong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.30 no.4
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    • pp.373-380
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    • 2006
  • Annubar is one of popular tools to measure the exhausted gas flow rate from the stacks. For the accurate monitoring of the amount of discharged pollutants, calibration of annubar is very important. Calibration of annubar has been carried out in a wind tunnel. When the length of annubar is longer than the test section size of wind tunnel, it is very difficult to find out typical value of annubar coefficients. So, a measurement technique to calibrate annubar longer than the size of the test section of wind tunnel must be developed. In the present study, an experiment is performed to measure the annubar coefficients in such a limited size of the wind tunnel. The experimental annubar coefficient by using a partial blocking technique is very close to the annubar coefficient of normal condition.

Study on Static Pressure Error Model for Pressure Altitude Correction (기압 고도의 정밀도 향상을 위한 정압 오차 모델에 관한 연구)

  • Jung, Suk-Young;Ahn, Chang-Soo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.4
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    • pp.47-56
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    • 2005
  • In GPS/INS/barometer navigation system for UAV, vertical channel damping loop was introduced to suppress divergence of the vertical axis error of INS, which could be reduced to the level of accuracy of pressure altitude measured by a pitot-static tube. Because static pressure measured by the pitot-static tube depends on the speed and attitude of the vehicle, static pressure error models, based on aerodynamic data from wind tunnel test, CFD analysis, and flight test, were applied to reduce the error of pressure altitude. Through flight tests and sensitivity analyses, the error model using the ratio of differential pressure and static pressure turned out to be superior to the model using only differential pressure, especially in case of high altitude flight. Both models were proposed to compensate the effect of vehicle speed change and used differential and static pressure which could be obtained directly from the output of pressure transducer.

A Study on the Characteristics of Multi-point Pilot Tube Flow-meter (다점 피토관 유량계의 특성에 관한 연구)

  • 임재명;윤복현;박경암
    • The KSFM Journal of Fluid Machinery
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    • v.4 no.2
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    • pp.35-43
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    • 2001
  • The flow characteristics passing a multi-point Pitot tube flow-meter of diamond shape and the characteristics of flow coefficients of the flow-meter are experimentally studied by varying combination of upstream rectangular dual elbows. The results provide the flow coefficients, which show good stability and reliability within the Reynolds number range coveted here in this study, and which can be used to measure flow-rates in practice. The variation of dual elbows upstream can change the velocity field so much that the flow pattern might thwart the precise flow measurement using the multi-point Pitot tube. The strongest swirl is detected in the case of $90^{\circ}$ dual elbow combination of all. In addition, it is observed that flow separation remains unchanged and occurs at the same point irrespective of various upstream dual elbow combinations.

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Flow Measurements and Performance Analysis using a 5-Hole Pitot Tube and a Rotating Hot-Wire Probe in an Axial Flow Fan (5공 피토관 및 회전 열선 유속계에 의한 축류 홴 내부 유동장 계측 및 평가)

  • Jang, Choon-Man;Kim, Kwang-Yong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.12
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    • pp.1750-1757
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    • 2003
  • This paper describes the flow measurements inside the blade passage of an axial flow fan by using a rotating hot-wire probe sensor from a relative flame of reference fixed to the rotor blades. The validity of fan rotor designed by a streamline curvature equation was performed by the measurement of the three-dimensional flow upstream and downstream of the fan rotor using a 5-hole pitot tube. The vortical flow structure near the rotor tip can be clearly observed by the measurements of a relative velocity and its fluctuation on quasi-orthogonal planes to a tip leakage vortex. Larger vortical flow, which results in higher blockage in the main flow, is formed according to decrease a flow rate. The vortical flow spreads out to the 30 percent span from the rotor tip at near stall condition. In the design operating condition, the tip leakage vortex is moved downstream while the center of the vortex keeps constant in the spanwise direction. Detailed characteristics of a velocity fluctuation with relation to the vortex were also analyzed.

Study on the calibration of a five-hole Pitot-tube for the wake measurement (반류 계측용 5공 피토관의 캘리브레이션 방법에 관한 연구)

  • Kim, W.J.;Kim, D.H.;Yoon, H.S.;Moon, D.Y.;Van, S.H.
    • Journal of the Society of Naval Architects of Korea
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    • v.34 no.2
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    • pp.11-19
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    • 1997
  • The new definition of calibration coefficients is proposed for a five-hole Pitot tube. Two-angle chart calibration other than one-angle variation is considered to improve the accuracy in the measurement of the three-dimensional velocity fields. Several sets of correlation coefficients are introduced for different shapes of the probe tip. The calibration method with one-angle variation is compared with the new two-angle chart calibration method and the improvement of the present method is clearly shown.

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Design of Pitot-Tube Configuration Using CFD Analysis and Optimization Techniques (CFD 해석 및 최적화 기법을 이용한 피토관 형상설계)

  • Kim, Do-Jun;Cheon, Young-Seong;Myong, Rho-Shin;Park, Chan-Woo;Cho, Tae-Hwan;Park, Young-Min;Choi, In-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.5
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    • pp.392-399
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    • 2008
  • Accurate measurement of speed and altitude of flying vehicles in air data system remains a critical technical issue. A highly reliable Pitot-static probe is required to obtain air data such as total pressure and static pressure. In this study, an analysis of the characteristics of flowfield around the Pitot-static probe was performed by using a Navier-Stokes CFD code. In addition, for the purpose of finding an optimal configuration, a technique based on the response surface method is applied to the problem with design parameters including shape of the nose section and cone angle. It is shown that the optimal configuration fulfills the MIL specification in wider range of high angles of attack.

Uncertainty Assessment of Gas Flow Measurement Using Multi-Point Pitot Tubes (다점 피토관을 이용한 기체 유량 측정의 불확도 평가)

  • Yang, Inyoung;Lee, Bo-Hwa
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.2
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    • pp.5-10
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    • 2016
  • Gas flow measurement in a closed duct was performed using multi-point Pitot tubes. Measurement uncertainty was assessed for this measurement method. The method was applied for the measurement of air flow into a gas turbine engine in an altitude engine test facility. 46 Pitot tubes, 15 total temperature Kiel probes and 9 static pressure tabs were installed in the engine inlet duct of inner diameter of 264 mm. Five tests were done in an airflow range of 2~10 kg/s. The flow was compressible and the Reynolds numbers were between 450,000 and 2,220,000. The measurement uncertainty was the highest as 6.1% for the lowest flow rate, and lowest as 0.8% for the highest flow rate. This is because the difference between the total and static pressures, which is also related to the flow velocity, becomes almost zero for low flow rate cases. It was found that this measurement method can be used only when the flow velocity is relatively high, e.g., 50 m/s. Static pressure was the most influencing parameter on the flow rate measurement uncertainty. Temperature measurement uncertainty was not very important. Measurement of boundary layer was found to be important for this type of flow rate measurement method. But measurement of flow non-uniformity was not very important provided that the non-uniformity has random behavior in the duct.

Experimental Approach for Estimation of Hydrodynamic Force Acting on a Submerged Streamlined Body Translating in a One-end-opened Cylindrical Tube (수중운동체의 실린더 관 내부 이동시 작용력 예측에 대한 실험적 접근)

  • Yeo, Dong-Jin;Kim, Yeon-Gyu;Kim, Dong-Hun
    • Journal of the Society of Naval Architects of Korea
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    • v.49 no.2
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    • pp.203-211
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    • 2012
  • The main object of this experiment is to estimate the hydrodynamic forces acting on a submerged streamlined body placed in a one-end-opened cylindrical tube moving with certain translational velocity. The best experimental design for this object is mimicking real situation, however sizes of model body and cylinder tube are just the same as those of real, for avoiding scale effects, mimicking real situation is not realizable. Hence, in this experiment, target body and cylindrical tube were designed to be towed with varying body position relative to cylindrical tube. For measuring hydrodynamic forces and flow velocity in the cylindrical tube, six one-component load cells and several one-hole Pitot tubes were used. Several conditions were checked with various end-plates those had different opening areas. Experiment results show that forces and flow velocity had different tendency with those expected, and the presence of a end-plate slows down the flow velocity in the cylindrical tube and affects pressure field in the tube to push the model submerged body forward of the tube. This tendency grows with decreasing opened area.