In the flight of air vehicles, accurate air data information is required to control them effectively. Especially, helicopters are often put in drastic motion involved with high angle of attacks in order to perform difficult missions. Among various sensors, the multi function probe (MFP) has been use...
In the flight of air vehicles, accurate air data information is required to control them effectively. Especially, helicopters are often put in drastic motion involved with high angle of attacks in order to perform difficult missions. Among various sensors, the multi function probe (MFP) has been used in the present study mainly owing to its advantages in structural simplicity and capability of providing various information such as static and total pressure, speed, and pitch and yaw angles. In this study, a five-hole multi-function probe (FHMFP) is developed and its calibration is conducted using multiple regressions. In this work a calibration study on the FHMFP, an air data sensor for helicopters, is reported. It is shown that the pitch and yaw angles' accuracy of calibration is ${\pm}0.91^{\circ}$ at a cone angle of $0^{\circ}{\sim}30^{\circ}$ and ${\pm}2.0^{\circ}$ at $30^{\circ}{\sim}43^{\circ}$, respectively, which is summarized in table 3.
In the flight of air vehicles, accurate air data information is required to control them effectively. Especially, helicopters are often put in drastic motion involved with high angle of attacks in order to perform difficult missions. Among various sensors, the multi function probe (MFP) has been used in the present study mainly owing to its advantages in structural simplicity and capability of providing various information such as static and total pressure, speed, and pitch and yaw angles. In this study, a five-hole multi-function probe (FHMFP) is developed and its calibration is conducted using multiple regressions. In this work a calibration study on the FHMFP, an air data sensor for helicopters, is reported. It is shown that the pitch and yaw angles' accuracy of calibration is ${\pm}0.91^{\circ}$ at a cone angle of $0^{\circ}{\sim}30^{\circ}$ and ${\pm}2.0^{\circ}$ at $30^{\circ}{\sim}43^{\circ}$, respectively, which is summarized in table 3.
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제안 방법
Recognizing the need to study a multi-function velocity direction sensor that enables simultaneous measurement of velocity, angle of attack, and angle of sideslip so as to improve the performance of air data systems for helicopters, as opposed to the existing method that measures velocity only, the present study aimed at designing a five-hole multi-function probe by using a CFD analysis and optimization techniques, and subsequently created FHMFP based on configuration design results. Wind tunnel tests were then carried out to apply the calibration method in multiple regressions to validate the performance of the five-hole multi-function probe.
Recognizing the need to study a multi-function velocity direction sensor that enables simultaneous measurement of velocity, angle of attack, and angle of sideslip so as to improve the performance of air data systems for helicopters, as opposed to the existing method that measures velocity only, the present study aimed at designing a five-hole multi-function probe by using a CFD analysis and optimization techniques, and subsequently created FHMFP based on configuration design results. Wind tunnel tests were then carried out to apply the calibration method in multiple regressions to validate the performance of the five-hole multi-function probe.
In this study, a CFD analysis was performed at the maximum angle of attack of the helicopter at 25°, and Tables 1 and 2 suggest differences in pressure obtained from analyses at 9 test points with the cone configuration and hemispherical configuration, respectively.
A hemispherical configuration pressure probe with a 48° hole position angle and 1 mm hole diameter was established through a comparison of calibration performance by different optimization results and angles.
The unknown flow angle can be expressed in two ways as pitch angle and yaw angle, and as cone angle and roll angle. In this study, test data measured through a spherical coordinate system can be expressed in rectangular coordinates through a simple process of coordinate conversion.
The calibration test was performed at a wind velocity of 31 m/s with the cone angle increasing from 0 to 45° at an interval of 5° and with the roll angle increasing from 0 to 360° at an interval of 10°.
The calibration test was performed at a wind velocity of 31 m/s with the cone angle increasing from 0 to 45° at an interval of 5° and with the roll angle increasing from 0 to 360° at an interval of 10°. In terms of the roll angle, to remove the effect of the backlash between the increasing direction and the dwindling direction, the test was performed using the direction of the increasing roll angle.
To validate the performance of the probe calibrated through the wind tunnel test, a random number table was used to abstract random angle combinations within a cone angle range from 0° to 45° and a roll angle range from 0° to 360°.
To validate the performance of the probe calibrated through the wind tunnel test, a random number table was used to abstract random angle combinations within a cone angle range from 0° to 45° and a roll angle range from 0 °to 360°.
For the wind tunnel test, configuration design of the fivehole probe was performed by applying a CFD analysis and an optimization technique; based on the results of the configuration design, a hemispherical five-hole probe with a hole diameter of 1 mm and a hole position angle of 48° was determined to be an excellent air data sensor, and was subsequently fabricated.
This study described a calibration technique for a five-hole, multi-function probe for an air data sensor used in helicopters. For the wind tunnel test, configuration design of the fivehole probe was performed by applying a CFD analysis and an optimization technique; based on the results of the configuration design, a hemispherical five-hole probe with a hole diameter of 1 mm and a hole position angle of 48° was determined to be an excellent air data sensor, and was subsequently fabricated.
The created probe was calibrated through a wind tunnel test. The test was carried out by applying a spherical coordinate system of the cone angle and the roll angle. To validate the performance of the probe calibrated through the wind tunnel test, a random number table was used to abstract random angle combinations within a cone angle range from 0° to 45° and a roll angle range from 0 °to 360°.
데이터처리
For each test point, 30 pressure values were obtained for 30 seconds and their average was used. Data used in the test were handled with a calibration technique that uses a multiple regression and mean function.
이론/모형
A far field boundary condition was set for the external flow field, and the model was made 10 times larger than the probe, as the effect of viscosity should not reach the probe’s tip[2]. In this study, Fluent V6 based on the compressible Navier-Strokes governing equation was used for the numerical analysis of the five-hole probe[3].
성능/효과
The comparison of the calibration results and measured values confirmed that a standard error of ± 0.91° was found at a cone angle of 0° ~ 30° and ± 2.0° at 30° ~ 43° .
참고문헌 (8)
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