The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform

Masanobu Namba - One of the best experts on this subject based on the ideXlab platform.

  • Lifting Surface Theory to predict aerodynamic forces induced by oscillating blades under interaction of three bladerows
    Journal of Sound and Vibration, 2009
    Co-Authors: Masanobu Namba, Hiroyuki Nakagawa, Ayumi Kubo
    Abstract:

    The paper presents the unsteady Lifting Surface Theory to predict unsteady aerodynamic forces on blades of aerodynamically coupled three annular bladerows. Blades of any one bladerow are assumed to be vibrating. The bladerows are assumed to be individually rotating with arbitrary rotational velocities, and therefore the model can be reduced to a rotor/stator/rotor model or a counter-rotating multi-rotor system model by appropriately specifying rotational velocity parameters. The details of the mathematical formulations and the solution procedures are described. Numerical studies were conducted. The disturbances produced by a simple harmonic blade vibration are composed of multiple frequency components because of aerodynamic interaction between bladerows in mutual rotational motions. Relative magnitudes of the frequency components of the unsteady aerodynamic forces are made clear. Not only the effects of nonoscillating neighboring bladerows on the unsteady aerodynamic response of the oscillating bladerow, but also the unsteady aerodynamic forces on nonoscillating neighboring bladerows induced by the oscillating bladerow are investigated.

  • Unsteady Lifting Surface Theory for Supersonic Through-Flow Fan
    JSME International Journal Series B, 1994
    Co-Authors: Masanobu Namba, Toshiya Hanada
    Abstract:

    The purpose of the present study is to predict analytically the unsteady loading on vibrating blades of a supersonic through-flow fan and investigate the aerodynamic instability. It is assumed that each blade operates with zero steady loading, and vibrates with small displacement amplitude, and a linearized unsteady Lifting Surface Theory for a supersonic through-flow fan on the basis of the finite radial eigenfunction series approximation is developed. Numerical results of the unsteady loadings and unsteady aerodynamic works are presented. The bending vibration with zero mean loading is always stable, and the torsional instability heavily depends upon relative locations of the leading edge Mach wave reflection point and the torsion axis.

  • unsteady Lifting Surface Theory based on double linearization concept for supersonic through flow fan
    Transactions of the Japan Society of Mechanical Engineers. B, 1994
    Co-Authors: Toshiya Hanada, Masanobu Namba
    Abstract:

    A full three-dimensional Lifting Surface Theory based on the double linearization concept is developed for a rotating annular cascade model operating at axial supersonic velocity. It is assumed that each blade vibrates with infinitesimal displacement amplitude under small mean loading. Vibration modes normal and parallel to the blade chord are considered. Numerical results are presented to investigate the mean loading effects on the aerodynamic instability of the blade motion. It is found that the bending motion can be unstable due to the presence of mean loading. Some numerical results compared with strip Theory predictions demonstrate significant three-dimensional effects on the unsteady aerodynamic force.

  • Lifting Surface Theory for Steady Aerodynamic Analysis of Ducted Counter Rotation Propfan
    Volume 1: Turbomachinery, 1992
    Co-Authors: Hidekazu Kodama, Masanobu Namba
    Abstract:

    A Lifting Surface Theory is developed to predict the steady performance for ducted counter rotation propfan with blade sweep. In solving the integral equation, the chordwise Lifting pressures on the blade Surfaces of front and rear rotors are expanded into a finite series at each radial collocation point, and the coefficients of the series are determined so that the blade Surface flow tangency conditions for both rotors are satisfied at the corresponding number of control points. Calculations are carried out for the propfans with subsonic relative flows, and the effect of the number of blades on the total pressure rise is studied using a probable blade model. The interference effect between the rotors and the effect of blade sweep on the steady performance are also demonstrated.Copyright © 1992 by ASME

  • unsteady Lifting Surface Theory for supersonic through flow fan
    Transactions of the Japan Society of Mechanical Engineers. C, 1992
    Co-Authors: Masanobu Namba, Toshiya Hanada
    Abstract:

    The purpose of this work is to predict analytically the unsteady loading on vibrating blades of a supersonic through-flow fan and investigate the aerodynamic instability. In order to deal with this problem, a linearized unsteady Lifting Surface Theory on the basis of the finite radial eigenfunction series approxmation is developed. It is assumed that each blade operates with zero mean loading, and vibrates with a small displacement amplitude. Numerical results for pure bending, pure torsional and combined bending and torsional vibrations are presented to demonstrate influences of interblade phase angle, location of torsion axis, axial Mach number and reduced frequency on the flutter boundary.

Koichi Koyama - One of the best experts on this subject based on the ideXlab platform.

  • Relation between the Lifting Surface Theory and the Lifting line Theory in the design of an optimum screw propeller
    Journal of Marine Science and Technology, 2013
    Co-Authors: Koichi Koyama
    Abstract:

    A Theory on an optimum screw propeller is described. The optimum means optimum efficiency of a propeller, that is, maximizing thrust horse power for a given shaft horse power. The Theory is based on the propeller Lifting Surface Theory. Circulation density (lift density) of the blade is determined by the Lifting Surface Theory on a specified condition in general. However, it is shown that, in the case of optimum condition, the circulation density is not determined by the Lifting Surface Theory, although the circulation distribution which is the chordwise integral of the circulation density is determined. The reason is that the governing equation of the optimization by the Lifting Surface Theory is reduced to that by the Lifting line Theory. This theoretical deduction is the main part of this paper. The importance of the Lifting line Theory in the design of the optimum propeller is made clear. Numerical calculations support the conclusion from the deduction. This is shown in the case of freely running propellers and in the case of wake adapted propellers.

Ray M. Chi - One of the best experts on this subject based on the ideXlab platform.

  • An unsteady Lifting Surface Theory for ducted fan blades
    Journal of Turbomachinery, 1993
    Co-Authors: Ray M. Chi
    Abstract:

    A frequency domain Lifting Surface Theory is developed to predict the unsteady aerodynamic pressure loads on oscillating blades of a ducted subsonic fan. The steady baseline flow as observed in the rotating frame of reference is the helical flow dictated by the forward flight speed and the rotational speed of the fan. The unsteady perturbation flow, which is assumed to be potential, is determined by solving an integral equation that relates the unknown jump in perturbation velocity potential across the Lifting Surface to the upwash velocity distribution prescribed by the vibratory motion of the blade. Examples of unsteady pressure distributions are given to illustrate the differences between the three-dimensional Lifting Surface analysis and the classical two-dimensional strip analysis. The effects of blade axial bending, bowing (i.e., circumferential bending), and sweeping on the unsteady pressure load are also discussed.

  • An Unsteady Lifting Surface Theory for Ducted Fan Blades
    Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls Diagnostics and Instrumentation; Education; IGTI Scholar, 1991
    Co-Authors: Ray M. Chi
    Abstract:

    A frequency domain Lifting Surface Theory is developed to predict the unsteady aerodynamic pressure loads on oscillating blades of a ducted subsonic fan. The steady baseline flow as observed in the rotating frame of reference is the helical flow dictated by the forward flight speed and the rotational speed of the fan. The unsteady perturbation flow, which is assumed to be potential, is determined by solving an integral equation that relates the unknown jump in perturbation velocity potential across the Lifting Surface to the upwash velocity distribution prescribed by the vibratory motion of the blade. Examples of unsteady pressure distributions are given to illustrate the differences between the three dimensional Lifting Surface analysis and the classical two dimensional strip analysis. The effects of blade axial bending, bowing (i.e., circumferential bending) and sweeping on the unsteady pressure load are also discussed.Copyright © 1991 by ASME

Toshiya Hanada - One of the best experts on this subject based on the ideXlab platform.

  • unsteady Lifting Surface Theory based on double linearization concept for supersonic through flow fan
    Transactions of the Japan Society of Mechanical Engineers. B, 1994
    Co-Authors: Toshiya Hanada, Masanobu Namba
    Abstract:

    A full three-dimensional Lifting Surface Theory based on the double linearization concept is developed for a rotating annular cascade model operating at axial supersonic velocity. It is assumed that each blade vibrates with infinitesimal displacement amplitude under small mean loading. Vibration modes normal and parallel to the blade chord are considered. Numerical results are presented to investigate the mean loading effects on the aerodynamic instability of the blade motion. It is found that the bending motion can be unstable due to the presence of mean loading. Some numerical results compared with strip Theory predictions demonstrate significant three-dimensional effects on the unsteady aerodynamic force.

  • Unsteady Lifting Surface Theory for Supersonic Through-Flow Fan
    JSME International Journal Series B, 1994
    Co-Authors: Masanobu Namba, Toshiya Hanada
    Abstract:

    The purpose of the present study is to predict analytically the unsteady loading on vibrating blades of a supersonic through-flow fan and investigate the aerodynamic instability. It is assumed that each blade operates with zero steady loading, and vibrates with small displacement amplitude, and a linearized unsteady Lifting Surface Theory for a supersonic through-flow fan on the basis of the finite radial eigenfunction series approximation is developed. Numerical results of the unsteady loadings and unsteady aerodynamic works are presented. The bending vibration with zero mean loading is always stable, and the torsional instability heavily depends upon relative locations of the leading edge Mach wave reflection point and the torsion axis.

  • unsteady Lifting Surface Theory for supersonic through flow fan
    Transactions of the Japan Society of Mechanical Engineers. C, 1992
    Co-Authors: Masanobu Namba, Toshiya Hanada
    Abstract:

    The purpose of this work is to predict analytically the unsteady loading on vibrating blades of a supersonic through-flow fan and investigate the aerodynamic instability. In order to deal with this problem, a linearized unsteady Lifting Surface Theory on the basis of the finite radial eigenfunction series approxmation is developed. It is assumed that each blade operates with zero mean loading, and vibrates with a small displacement amplitude. Numerical results for pure bending, pure torsional and combined bending and torsional vibrations are presented to demonstrate influences of interblade phase angle, location of torsion axis, axial Mach number and reduced frequency on the flutter boundary.

Hidekazu Kodama - One of the best experts on this subject based on the ideXlab platform.

  • Lifting Surface Theory for Steady Aerodynamic Analysis of Ducted Counter Rotation Propfan
    Volume 1: Turbomachinery, 1992
    Co-Authors: Hidekazu Kodama, Masanobu Namba
    Abstract:

    A Lifting Surface Theory is developed to predict the steady performance for ducted counter rotation propfan with blade sweep. In solving the integral equation, the chordwise Lifting pressures on the blade Surfaces of front and rear rotors are expanded into a finite series at each radial collocation point, and the coefficients of the series are determined so that the blade Surface flow tangency conditions for both rotors are satisfied at the corresponding number of control points. Calculations are carried out for the propfans with subsonic relative flows, and the effect of the number of blades on the total pressure rise is studied using a probable blade model. The interference effect between the rotors and the effect of blade sweep on the steady performance are also demonstrated.Copyright © 1992 by ASME

  • Unsteady Lifting Surface Theory for a rotating transonic cascade of swept blades
    Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls Diagnostics and Instrumentation; Education; IGTI Scholar, 1991
    Co-Authors: Hidekazu Kodama, Masanobu Namba
    Abstract:

    A Lifting Surface Theory is developed to predict the unsteady three-dimensional aerodynamic characteristics for a rotating transonic annular cascade of swept blades. An improved method is used to solve the integral equation for the unsteady blade loading. Numerical examples are presented to demonstrate effects of the sweep on the blade flutter and on the acoustic field generated by interaction of rotating blades with a convected sinusoidal gust. It is found that, in the case of transonic rotors, the magnitude of total aerodynamic work due to the blade vibration is reduced at large sweep angles, however blade sweep is not beneficial for noise reduction.Copyright © 1991 by ASME