• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.84-90
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• 2000

Integrated tools are developed for the analysis of the aerodynamic performance and aeroacoustics of helicopter rotors. Heli-NK(Helicopter Navier-Stokes & Kirchhoff) code is for hovering and heli-PA(Helicopter Panel & Acoustic analogy) for forward flight. The former showed its ability to predict the hovering efficiency and high-speed impulsive noise level. Thrust calculation, noise levels, and noise directivity patterns are investigated to confirm the availability of the latter. With some proper validation and improvements. these codes will be more useful and practical.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.116-119
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• 2007

In this study the unsteady aerodynamic analysis of a hovering helicopter rotor is performed. For the accurate flow field analysis Euler equations and the free wake method are coupled. The Euler equations are solved to find the pressure distribution around the rotor, and free wake method is used to give the boundary condition for the solution of Euler equations. Also, vortex strength and wake motion after the rotor are simulated by the free wake method. The accuracy of the present method is compared with the source sink model. The present method is applied to the hovering Caradonna-Tung rotor and compared with experimental results.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2599-2601
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• 2000

A helicopter control problem has been researched with many control theory. Especially, study of the hovering flight attitude control of a helicopter has been brisked since 60s with multivariable control theory. In this paper, the modeling is interpreted through the 6-freedom equation. To getting a entire equation, species of parameters and charts are adapted. The $H_2/H_{\infty}$ controller is acquired by mixing the $H_2$ control theory and the $H_{\infty}$ control theory. The $H_2$ control theory is reasonable one to increase the performance of a plant, and the $H_{\infty}$ control theory secures the robust stability. The simulation shows that the helicopter system is being controlled while maintaining performance and robust stability against perturbation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.77.6-77
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• 2001

R/C helicopter has been used to several fields of military affairs, investigation, searching and toys because it has small size, hovering and vertical take-off characteristics etc. Therefore it needs more realizable control method. The paper introduces simulation and experimental results for control of a helicopter training simulator by self tuning control method. It is assumed that the helicopter is operated at the state of hovering motion and the model is induced. The self tuning control method incorporates the concepts of the well known internal model principle and annihilator polynomial for reference input and disturbance. The controller design is separated into two cases that the plant parameters are known or not. To realize ...

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.63.2-63
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• 2002

● Introduction ● System Identification ● PD Controller Design ● Verifying the Model & Simulation ● Experiment for Attitude Control ● Results ● Conculsions

• 한국항공운항학회:학술대회논문집
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• 2004.11a
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• pp.279-284
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• 2004

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.8
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• pp.719-727
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• 2008

A 3-D compressible Navier-Stokes solver using overlapped grids is developed to predict a flow-field around a hovering rotor. The flow solver is verified by a parametric study with the grid spacing of wake grid, spatial accuracy and turbulence model. Computations are performed with different Chimera grid systems. Computational results are compared with the experimental data of Caradonna et al. for both blade loading and the tip vortex behavior. Numerical results show good agreements with experiments for the distribution of surface pressure and tip vortex behavior. Pressure distributions over the blade have marginal differences for different numerical methods, whereas large discrepancies are seen in the prediction of the wake behavior. Results unexpectedly show that the vortex strength from an automated cut-paste Chimera grid is weaker than that from the conventional Chimera grid.

• Journal of Advanced Navigation Technology
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• v.20 no.6
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• pp.574-579
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• 2016

Unlike general unmanned aerial vehicles, the quad-rotor is attracting the attention of many people because of simple structure and very useful value. However, as the interest in drones increases, the safety and location of vehicles are becoming more important provide against aviation safety accidents or lost accidents. Therefore, in this paper, we propose a tracking system that stabilizes the model with a simple controller by linearized modeling and grasp tilt angle data from various sensor through the filter. The developed tracking system transmits the position of the quad-rotor in flight to the computer and shows it through the route, so it can check the flight path and various information such as flight speed and altitude at the same time. Then the sensor used in the actual quad-rotor can not measure exact sensor data for disturbance and vibration. So we use sensor fusion of Kalman filter and Complementary filter to overcome this problem and the stability of the quad-rotor hovering is realized by PID control. Through simulation, various information such as the speed, position, and altitude of the quad-rotor were confirmed in real time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.3
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• pp.201-208
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• 2012

In this paper, a series of experiment is performed for a scaled hovering rotor in a semi-anechoic chamber and the results are compared to the noise spectra predicted by using Lowson's loading noise equation and FW-H equation. It was founded that the sound directivity pattern for both experiments and predictions are similar in their trend. Meanwhile the FW-H equation showed better agreement with experiments in the near-field noise spectra, but at the far-field the Lowson's equation performed better. The discrete noise are known to be proportional to the loading on the blades, which can be controlled by collective pitch angle of the blades. It was founded that the predicted spectra with FW-H equation come close to the measured noise spectra in low collective pitch, but in high collective pitch angles the Lowson's equation be more reliable.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.399-405
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• 2021

In the present study, ground tests and CFD simulations for a ducted fan system were performed to verify the hovering performance of the ducted fan system designed by KARI rotorcraft team. Six blades were composed for the ducted fan, and target rotating speed of the fan was decided to 4,000 RPM. Collective pitch angles were considered from 20 degrees to 36 degrees. The test data were obtained by increasing the rotating speed up to 4,000 RPM in 1,000 RPM increments. The CFD simulations were considered only 4,000 RPM of rotating speed. The hovering performance was represented by thrust, power, duct thrust ratio, and FM(Figure of Merit). Reliability of the performance results was ensured through the test and simulation results, and it was found that the target performance was achieved under conditions above 31 degrees of the pitch angle.