The Experts below are selected from a list of 43803 Experts worldwide ranked by ideXlab platform

Jinsoo Cho - One of the best experts on this subject based on the ideXlab platform.

  • Unsteady Aerodynamic Analysis and Wake Simulation of Helicopter Rotors using the Time-Domain Panel Method
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 2012
    Co-Authors: Seawook Lee, Leesang Cho, Jinsoo Cho
    Abstract:

    An unsteady panel method based on potential flow theory is developed for unsteady Aerodynamic Analysis of helicopter rotors. The panel method uses a piecewise constant source and doublet singularities in the solution. This potential-based panel method is based on the Dirichlet boundary condition coupled with a time-stepping method. The proposed method uses a time-stepping loop to simulate the unsteady motion of helicopter rotors. A free wake model is used for the wake simulation of a helicopter rotor. The proposed method is validated by comparing our results with experimental data. The incompressible results of the proposed method for helicopter rotors are in good agreement with the experimental data for hovering and forward flight. The proposed method can be used for practical applications such as Aerodynamic designs and the Analysis of various helicopter rotor configurations.

  • Aerodynamic Analysis of the Helicopter Rotor Using the Time-Domain Panel Method
    Volume 2: Fora, 2009
    Co-Authors: Seawook Lee, Hyunmin Choi, Leesang Cho, Jinsoo Cho
    Abstract:

    Recently, Aerodynamic Analysis of the helicopter rotor using computational fluid dynamics (CFD) is widely carried out with high accuracy. But, it is very long time to calculate Aerodynamic performances and it is difficult to simulate the wake shape of the helicopter rotor using CFD Analysis. In this research the time-domain panel method, which uses a numerical technique based on the piecewise constant source and doublet singularities, is applied to the Analysis and prediction of the unsteady Aerodynamic characteristics of helicopter rotor in a potential flow. And the free wake model is used for wake simulation. The results of present method are compared with the results of experiment of a helicopter rotor in hover and in forward flight. Results show good agreement with the experimental results.Copyright © 2009 by ASME

  • Unsteady Aerodynamic Analysis of Tandem Flat Plates in Ground Effect
    Journal of Aircraft, 2002
    Co-Authors: Cheolheui Han, Younghyun Yoon, Jinsoo Cho
    Abstract:

    Unsteady Aerodynamic Analysis of flat plates in tandem configuration flying near the ground is done using a discrete vortex method. The vortex core modeling and the core addition scheme are needed for the better prediction of the unsteady downwash on the flat plates and coupled Aerodynamic interference between the plates. For the validation of the present method, the computed wake shapes of both single flat plate and flat plates in tandem configuration are compared with flow visualization and other numerical result. The predicted wake shapes and the Aerodynamic characteristics of the flat plates in tandem configuration show that the unsteady ground effect can be of considerable importance in the performance of wings in tandem configuration.

  • Unsteady Aerodynamic Analysis of ducted fans
    Journal of Propulsion and Power, 1991
    Co-Authors: Marc H. Williams, Jinsoo Cho, William N. Dalton
    Abstract:

    A steady and unsteady Aerodynamic Analysis of ducted fans has been developed using a frequency domain panel method based on three-dimensional linear compressible lifting surface theory. The duct is assumed to be a finite-length right-circular cylinder concentric with the rotor. Both the duct and rotor blades are modeled by simple harmonic rotating doublet sheets. The model spans a single reference passage with the influence of the rest of the configuration included by symmetry. Results for the steady state performance characteristics of a ducted rotor are compared with an Euler calculation. The effect of the duct on the unsteady Aerodynamic forces induced by blade vibration is examined, and comparisons are made with two-dimensional unsteady cascade theory* Finally, it is shown that the duct has an adverse effect on the aeroelastic stability of the rotor.

John T. Batina - One of the best experts on this subject based on the ideXlab platform.

  • CFD Methods Development Considerations for Unsteady Aerodynamic Analysis
    ICASE NASA LaRC Series, 1993
    Co-Authors: John T. Batina
    Abstract:

    The development of computational fluid dynamics (CFD) methods for unsteady Aerodynamic Analysis is described. Special emphasis is placed on considerations that are required for application of the methods to unsteady Aerodynamic flow problems. Two broad categories of topics are discussed including grid considerations and algorithm development considerations, and example calculations are presented to illustrate the major points. Although the primary application of these CFD methods is to relatively low-frequency oscillatory phenomena such as flutter, the ideas that are presented may be of value to developers of computational aeroacoustics methods for predicting high-frequency acoustics.

  • unsteady euler algorithm with unstructured dynamic mesh for complex aircraft Aerodynamic Analysis
    AIAA Journal, 1991
    Co-Authors: John T. Batina
    Abstract:

    An Euler solution algorithm is presented for unsteady Aerodynamic Analysis of complex-aircr aft configurations. The flow solver involves a multistage Runge-Kutta time-stepping scheme that uses a finite-volume spatial discretization on an unstructured grid made up of tetrahedra. A significant contribution of the research is the development and implementation of a moving mesh algorithm that is employed for problems involving static or dynamic deformation of the aircraft. The mesh algorithm is a general procedure that can treat realistic motions and deformations of complex-aircraft configurations. Steady and unsteady results are presented for a supersonic fighter configuration to demonstrate applications of the Euler solver and dynamic mesh algorithm. The unsteady flow results were obtained for the aircraft oscillating harmonically in a complete-vehicle bending mode. Effects of angle of attack and reduced frequency on instantaneous pressures and force responses were investigated. The paper presents descriptions of the Euler solver and dynamic mesh algorithm along with results that assess the capability.

  • UNSTEADY EULER ALGORITHM WITH UNSTRUCTURED DYNAMIC MESH FOR COMPLEX – AIRCRAFT Aerodynamic Analysis
    AIAA Journal, 1991
    Co-Authors: John T. Batina
    Abstract:

    An Euler solution algorithm is presented for unsteady Aerodynamic Analysis of complex-aircr aft configurations. The flow solver involves a multistage Runge-Kutta time-stepping scheme that uses a finite-volume spatial discretization on an unstructured grid made up of tetrahedra. A significant contribution of the research is the development and implementation of a moving mesh algorithm that is employed for problems involving static or dynamic deformation of the aircraft. The mesh algorithm is a general procedure that can treat realistic motions and deformations of complex-aircraft configurations. Steady and unsteady results are presented for a supersonic fighter configuration to demonstrate applications of the Euler solver and dynamic mesh algorithm. The unsteady flow results were obtained for the aircraft oscillating harmonically in a complete-vehicle bending mode. Effects of angle of attack and reduced frequency on instantaneous pressures and force responses were investigated. The paper presents descriptions of the Euler solver and dynamic mesh algorithm along with results that assess the capability.

Haifa Xiang - One of the best experts on this subject based on the ideXlab platform.

  • nonlinear aerostatic and Aerodynamic Analysis of long span suspension bridges considering wind structure interactions
    Journal of Wind Engineering and Industrial Aerodynamics, 2002
    Co-Authors: Xinju Zhang, Haifa Xiang
    Abstract:

    Abstract The aerostatic and Aerodynamic behaviors of a long-span suspension bridge are of serious engineering concern. As the span length increases, the nonlinear effects due to wind-structure interactions are becoming unnegligible in determining the aerostatic and Aerodynamic behaviors of long-span suspension bridges. In this paper, an approach of three-dimensional nonlinear aerostatic and Aerodynamic Analysis is presented firstly, in which the nonlinearities of structural geometric, dynamic characteristics and aeroelastic forces due to the large deformation under the static wind loading are considered. Numerical analyses are then performed on the three-dimensional finite element model of a suspension bridge with a main span length of 1490 m. The effectiveness of the proposed approach is finally demonstrated. The results show that the nonlinear effects have a significant influence on the aerostatic and Aerodynamic behaviors of long-span suspension bridges.

Cindy W Albertson - One of the best experts on this subject based on the ideXlab platform.

  • aircraft high lift Aerodynamic Analysis using a surface vorticity solver
    54th AIAA Aerospace Sciences Meeting, 2016
    Co-Authors: Erik D Olson, Cindy W Albertson
    Abstract:

    This study extends an existing semi-empirical approach to high-lift Analysis by examining its effectiveness for use with a three-dimensional Aerodynamic Analysis method. The aircraft high-lift geometry is modeled in Vehicle Sketch Pad (OpenVSP) using a newlydeveloped set of techniques for building a three-dimensional model of the high-lift geometry, and for controlling flap deflections using scripted parameter linking. Analysis of the lowspeed Aerodynamics is performed in FlightStream, a novel surface-vorticity solver that is expected to be substantially more robust and stable compared to pressure-based potentialflow solvers and less sensitive to surface perturbations. The calculated lift curve and drag polar are modified by an empirical lift-effectiveness factor that takes into account the effects of viscosity that are not captured in the potential-flow solution. Analysis results are validated against wind-tunnel data for The Energy-Efficient Transport AR12 low-speed wind-tunnel model, a 12-foot, full-span aircraft configuration with a supercritical wing, full-span slats, and part-span double-slotted flaps.

Seawook Lee - One of the best experts on this subject based on the ideXlab platform.

  • Unsteady Aerodynamic Analysis and Wake Simulation of Helicopter Rotors using the Time-Domain Panel Method
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 2012
    Co-Authors: Seawook Lee, Leesang Cho, Jinsoo Cho
    Abstract:

    An unsteady panel method based on potential flow theory is developed for unsteady Aerodynamic Analysis of helicopter rotors. The panel method uses a piecewise constant source and doublet singularities in the solution. This potential-based panel method is based on the Dirichlet boundary condition coupled with a time-stepping method. The proposed method uses a time-stepping loop to simulate the unsteady motion of helicopter rotors. A free wake model is used for the wake simulation of a helicopter rotor. The proposed method is validated by comparing our results with experimental data. The incompressible results of the proposed method for helicopter rotors are in good agreement with the experimental data for hovering and forward flight. The proposed method can be used for practical applications such as Aerodynamic designs and the Analysis of various helicopter rotor configurations.

  • Aerodynamic Analysis of the Helicopter Rotor Using the Time-Domain Panel Method
    Volume 2: Fora, 2009
    Co-Authors: Seawook Lee, Hyunmin Choi, Leesang Cho, Jinsoo Cho
    Abstract:

    Recently, Aerodynamic Analysis of the helicopter rotor using computational fluid dynamics (CFD) is widely carried out with high accuracy. But, it is very long time to calculate Aerodynamic performances and it is difficult to simulate the wake shape of the helicopter rotor using CFD Analysis. In this research the time-domain panel method, which uses a numerical technique based on the piecewise constant source and doublet singularities, is applied to the Analysis and prediction of the unsteady Aerodynamic characteristics of helicopter rotor in a potential flow. And the free wake model is used for wake simulation. The results of present method are compared with the results of experiment of a helicopter rotor in hover and in forward flight. Results show good agreement with the experimental results.Copyright © 2009 by ASME