• Journal of computational fluids engineering
• /
• v.13 no.4
• /
• pp.45-49
• /
• 2008

The present paper describes the results of performance analysis for UH-60A rotor blade in hover. For the numerical simulations, commercial CFD software, FLUENT was used with Spalart-Allmaras turbulence model. The flow solver was based on node based scheme and second order spatial accuracy options was used for simulations. For the enhancement of wake capturing capability, high resolution grid was used around tip vortex region. Granting that somewhat over-prediction of thrust was observed near blade tip region, performance was well correlated with experimental data within 3% accuracy in the operating region. Finally it was shown that the present flow solver can be used as a preliminary performance analysis tool for hovering helicopter rotor blades.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.4
• /
• pp.329-335
• /
• 2009

The unsteady panel and time-marching free wake are applied to the rotor aerodynamics and wake behaviour. Numerical results of panel and free wake are compared and validated with experimental data. Using these methods, unsteady rotor aerodynamics in BVI condition is analyzed and discussed in detail.

• 한국전산유체공학회:학술대회논문집
• /
• 2007.10a
• /
• pp.73-76
• /
• 2007

The present paper describes the results of performance analysis for UH-60A rotor blade in hover. For the numerical simulations, commercial CFD software, FLUENT was used with Spalart-Allmaras turbulence model. The flow solver was based on node based scheme and second order spatial accuracy options was used for simulations. For the enhancement of wake capturing capability, high resolution grid was used around tip vortex region. Granting that somewhat over prediction of thrust was observed near blade tip region, performance was well correlated with experimental data within 3% accuracy in the operating region. Finally it was shown that the present flow solver can be used for preliminary performance analysis tool for hovering helicopter rotor blades.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03a
• /
• pp.251-255
• /
• 2008

Flow field around helicopter involves incompressible flow near the blade root and compressible flow at the blade tip. A problem occurs for low Mach number flow due to the stiffness of the governing equations. Time-derivative preconditioning techniques have been incorporated to reduce the stiffness that occurs at low speed region. The preconditioned form of the compressible Navier-Stokes and Euler equations is used. Computations are performed for the Caradonna-Tung's hovering and non-lifting forward flight case. Computational results are in good agreement with the experimental data.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.10a
• /
• pp.251-255
• /
• 2008

Flow field around helicopter involves incompressible flow near the blade root and compressible flow at the blade tip. A problem occurs for low Mach number flow due to the stiffness of the governing equations. Time-derivative preconditioning techniques have been incorporated to reduce the stiffness that occurs at low speed region. The preconditioned form of the compressible Navier-Stokes and Euler equations is used. Computations are performed for the Caradonna-Tung's hovering and non-lifting forward flight case. Computational results are in good agreement with the experimental data.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.2
• /
• pp.101-107
• /
• 2007

A coaxial rotor flying robot is developed for surveying and reconnoitering various circumstances under calamity environment. The robot has two contrarotating rotors on a common axis, an embedded microcontroller, an IMU(Inertial Measurement Unit), an IR sensor for height control, a micro camera for surveillance, ultrasonic position sensors and wireless communication devices. A bell-bar mounted on the top of the upper rotor hub increases stability and improves flight performance. In this paper, we present a dynamic model of a coaxial rotor flying robot and design an embedded controller far the robot, and implement them to control the developed flying robot. Experimental results show that the proposed controller is valid for autonomous hovering and position control.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.1
• /
• pp.58-64
• /
• 2007

In this paper, the stabilization problem of the image stabilization system(ISS) that captures the image of an object on the ground by remote sensing is considered. The ISS should be stable under outer disturbance such as helicopter vibration for tracking line of sight. Although PID controllers are optimized for the system, disturbances cause the instability of the system. To minimize the effect of the disturbance, the time-delayed control method is used to compensate for uncertainties. Simulation studies are performed and experiments are conducted to confirm the simulation results. Performances of PID control and time-delayed control methods are compared.

• The KSFM Journal of Fluid Machinery
• /
• v.15 no.5
• /
• pp.20-26
• /
• 2012

An APU(Auxiliary Power Unit) for helicopters has been developed in Korea and tested at the AETF(altitude engine test facility) in KARI(Korea Aerospace Research Institute) for the purpose of the military qualification. A cell correlation test was performed before the official test, and the results are within the tolerance. The APU has the capability of supplying electric power as well as compressed air to the helicopters. It was tested at bleed extraction conditions, electric power extraction conditions, and maximum continuous concurrent power conditions within the entire helicopter flight envelop. Some special test equipments were implemented for the measurement of air flowrate, electric power and so on. The tests were successfully performed and their results satisfy the requirements of the helicopters.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.08a
• /
• pp.95-101
• /
• 2003

A three dimensional inviscid parallel flow solver has been developed for the simulation of rotor blades in forward flight. The computational domain is divided into stationary and rotating zones for the more efficient mesh adaptation. The conservative mesh treatment algorithm is used for the convection of flow variables and fluxes across the sliding boundary. A deforming mesh algorithm using modified spring analogy is used for the blade motion. In the present paper, detail descriptions of numerical analysis for forward flight are introduced. Some results are presented for a two bladed AH-1G rotor and compared with experimental data.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.6
• /
• pp.981-987
• /
• 1997

Modern helicopter rotor blades with non-homogeneous cross section composed of anisotropic material rquire highly sophisticated structural analysis. Variation in cross section geometry makes this task of analysis more complicated. Since rotor blades generally are much longer than their lateral dimensions, one-dimensional models seem feasible, at least from a computational point of view. Therefore determination of the principal coordinate system is very important to remove the structural coupling for one-dimensional beam modelling. In this study, shear center, and principal direction. The method will be verified by comparing the results with confirmed experimental results.