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Michael Kingan - One of the best experts on this subject based on the ideXlab platform.

  • Time-domain analysis of Contra-Rotating Propeller noise: wake interaction with a downstream Propeller blade
    Journal of Fluid Mechanics, 2020
    Co-Authors: Michael Kingan, A. B. Parry
    Abstract:

    This paper describes a theoretical study – in the time domain – of sound from the interaction of the steady component of the viscous wakes of an upstream Propeller with a downstream Contra-Rotating Propeller blade. The study incorporates a two-dimensional model of the upstream Propeller wakes and a quasi-three-dimensional blade response function that accounts for downstream blade sweep. For a blade with a straight leading edge, the sound at the observer location, radiated from each blade radius, consists of a series of impulses whose peaks are shown to be influenced by micro Doppler effects and to correspond to the impingement of the Propeller wake centrelines on the leading edge of the downstream blade. For radiation from the entire blade span, it is shown that constructive interference of the impulses from all radii can produce impulsive sound of very high amplitude, whereas dephasing of these impulses can reduce significantly the total acoustic signal. For a downstream Propeller blade with a swept leading edge, it is shown how the sweep can be designed to ensure that these impulses are de-phased, resulting in significantly lower-amplitude sound at selected observer locations. Finally, to guarantee that the radiated sound is reduced at all possible observer locations, it is shown that the blade leading-edge sweep must be large enough that the trace velocity of the wake centreline, across the leading edge of the downstream Propeller blade, is subsonic across the entire span. The benefits are demonstrated for representative blade designs.

  • Acoustic theory of the many-bladed Contra-Rotating Propeller: The effects of sweep on noise enhancement and reduction
    Journal of Sound and Vibration, 2020
    Co-Authors: Michael Kingan, A. B. Parry
    Abstract:

    Abstract In the asymptotic theory of Propeller noise the far-field noise is dominated by small regions of the Propeller representing interior stationary points or boundary critical points. For Contra-Rotating Propellers, the wake-interaction solutions can thereby be written in closed form as simple algebraic expressions which still retain the effects of swept blade-gust interaction. In this paper, these asymptotic solutions are used to investigate how blade sweep can lead to enhanced or reduced noise radiation. In particular, it is shown how the locations of the interior stationary points vary with sweep and, consequently, how sweep can be used to control noise. Results are shown for a family of critical designs that have enhanced noise radiation arising from a continuum of interior stationary points. The dominant interior stationary points can be completely removed for particular tones and directions (sub-critical designs), even in cases for which the wake-rear Propeller aerodynamic interaction remains super-critical. Furthermore, the interior stationary points can be completely removed for all tones and directions (universally sub-critical designs); in these cases the wake interactions are sub-critical across the entire span of the blade, the resultant tones have low radiation efficiency and further increases in sweep lead to significant reductions in noise levels. Designs are presented, with corresponding noise calculations, that demonstrate these substantial noise benefits.

  • Acoustic theory of the many-bladed Contra-Rotating Propeller: physics of the wake interaction noise critical sources
    Journal of Fluid Mechanics, 2019
    Co-Authors: A. B. Parry, Michael Kingan
    Abstract:

    In the theory of interaction noise from Contra-Rotating Propellers with many blades, the usual far-field radiation formulae can be re-cast as a double integral, over a source surface, which can be evaluated asymptotically solely in terms of the contributions from critical points. The paper shows that these critical points have a particularly interesting physical meaning. They relate to locations on an event line, running between hub and tip, that represent the locus of the wake–blade interactions at a fixed point in time. The event line rotates at the speed of the spinning interaction tone but does not coincide with the radial variation in either the wake location or the rear blade leading edge. At the precise critical locations on the event line, it is shown that the Mach number of the event line is unity in the direction of the observer (the sonic condition) and the tangent to the event line – at a fixed time – is normal to a line drawn between it and the observer (the normal-edge condition). The zero-mode case is also considered, for which we show that, even though the event line rotates at infinite speed, there can still exist locations that satisfy the sonic and normal-edge conditions. The paper also discusses the physical meaning of the lower-order boundary solutions from the hub and tip.

  • Acoustic theory of the many-bladed Contra-Rotating Propeller: analysis of the effects of blade sweep on wake interaction noise
    Journal of Fluid Mechanics, 2019
    Co-Authors: Michael Kingan, A. B. Parry
    Abstract:

    An analytical model is presented for the wake interaction tones produced by a Contra-Rotating Propeller. We re-cast the usual far-field radiation formulae as a double integral over a nominal Propeller source annulus. Assuming that the number of blades on both Propellers is large, we evaluate the integral asymptotically in terms of its leading-order contributions from interior stationary or boundary critical points which represent the specific locations on the Propeller annulus that dominate the sound radiation. The asymptotic approach is powerful producing results in the form of one-line algebraic formulae that contain no integrals or special functions yet remain accurate. The asymptotics show that sweep is not necessarily beneficial and can cause the blade design to become critical for particular tones and directions in terms of a continuum of interior points distributed along a line on the Propeller source annulus producing a higher-order result and thus an enhanced radiated sound field. The paper also shows how the interior points are completely consistent with the sub- or super-critical gust response of a swept blade. Tones with low and zero azimuthal mode order are treated as special cases and the asymptotics show that, as the mode order reduces, the radiated sound becomes concentrated around the flight axis where even higher-order solutions are possible, including rings and annuli of stationary points around the Propeller annulus. Full numerical calculations confirm the accuracy of the asymptotic approach.

  • Relative importance of open rotor tone and broadband noise sources
    17th AIAA CEAS Aeroacoustics Conference (32nd AIAA Aeroacoustics Conference), 2011
    Co-Authors: Michael Kingan, Vincent P. Blandeau, Brian J. Tester, Phillip Joseph, Anthony B. Parry
    Abstract:

    A study is made of the noise levels and spectral characteristics of three Contra-Rotating Propeller rigs: rig 140 tested in 1989, rig 145 build 1 tested in 2008, and rig 145 build 2 tested in 2010. We use tone deletion techniques, applied to the inflow microphone data, to show the relative importance of Propeller broadband noise to Propeller tones with increasing frequency and, in particular, that by the time we reach only moderate frequencies, the one third octave spectra become dominated by the broadband noise components. We also show that the broadband noise continues to be important as blade speed and rig thrust are varied and that these spectral characteristics are present on both modern and older Contra-Rotating Propeller designs – even those with a profusion of tones and strong tone protusion. We also show how the tone and broadband noise levels have reduced with more recent, and aeroacoustically improved, blade designs

A. B. Parry - One of the best experts on this subject based on the ideXlab platform.

  • Time-domain analysis of Contra-Rotating Propeller noise: wake interaction with a downstream Propeller blade
    Journal of Fluid Mechanics, 2020
    Co-Authors: Michael Kingan, A. B. Parry
    Abstract:

    This paper describes a theoretical study – in the time domain – of sound from the interaction of the steady component of the viscous wakes of an upstream Propeller with a downstream Contra-Rotating Propeller blade. The study incorporates a two-dimensional model of the upstream Propeller wakes and a quasi-three-dimensional blade response function that accounts for downstream blade sweep. For a blade with a straight leading edge, the sound at the observer location, radiated from each blade radius, consists of a series of impulses whose peaks are shown to be influenced by micro Doppler effects and to correspond to the impingement of the Propeller wake centrelines on the leading edge of the downstream blade. For radiation from the entire blade span, it is shown that constructive interference of the impulses from all radii can produce impulsive sound of very high amplitude, whereas dephasing of these impulses can reduce significantly the total acoustic signal. For a downstream Propeller blade with a swept leading edge, it is shown how the sweep can be designed to ensure that these impulses are de-phased, resulting in significantly lower-amplitude sound at selected observer locations. Finally, to guarantee that the radiated sound is reduced at all possible observer locations, it is shown that the blade leading-edge sweep must be large enough that the trace velocity of the wake centreline, across the leading edge of the downstream Propeller blade, is subsonic across the entire span. The benefits are demonstrated for representative blade designs.

  • Acoustic theory of the many-bladed Contra-Rotating Propeller: The effects of sweep on noise enhancement and reduction
    Journal of Sound and Vibration, 2020
    Co-Authors: Michael Kingan, A. B. Parry
    Abstract:

    Abstract In the asymptotic theory of Propeller noise the far-field noise is dominated by small regions of the Propeller representing interior stationary points or boundary critical points. For Contra-Rotating Propellers, the wake-interaction solutions can thereby be written in closed form as simple algebraic expressions which still retain the effects of swept blade-gust interaction. In this paper, these asymptotic solutions are used to investigate how blade sweep can lead to enhanced or reduced noise radiation. In particular, it is shown how the locations of the interior stationary points vary with sweep and, consequently, how sweep can be used to control noise. Results are shown for a family of critical designs that have enhanced noise radiation arising from a continuum of interior stationary points. The dominant interior stationary points can be completely removed for particular tones and directions (sub-critical designs), even in cases for which the wake-rear Propeller aerodynamic interaction remains super-critical. Furthermore, the interior stationary points can be completely removed for all tones and directions (universally sub-critical designs); in these cases the wake interactions are sub-critical across the entire span of the blade, the resultant tones have low radiation efficiency and further increases in sweep lead to significant reductions in noise levels. Designs are presented, with corresponding noise calculations, that demonstrate these substantial noise benefits.

  • Acoustic theory of the many-bladed Contra-Rotating Propeller: physics of the wake interaction noise critical sources
    Journal of Fluid Mechanics, 2019
    Co-Authors: A. B. Parry, Michael Kingan
    Abstract:

    In the theory of interaction noise from Contra-Rotating Propellers with many blades, the usual far-field radiation formulae can be re-cast as a double integral, over a source surface, which can be evaluated asymptotically solely in terms of the contributions from critical points. The paper shows that these critical points have a particularly interesting physical meaning. They relate to locations on an event line, running between hub and tip, that represent the locus of the wake–blade interactions at a fixed point in time. The event line rotates at the speed of the spinning interaction tone but does not coincide with the radial variation in either the wake location or the rear blade leading edge. At the precise critical locations on the event line, it is shown that the Mach number of the event line is unity in the direction of the observer (the sonic condition) and the tangent to the event line – at a fixed time – is normal to a line drawn between it and the observer (the normal-edge condition). The zero-mode case is also considered, for which we show that, even though the event line rotates at infinite speed, there can still exist locations that satisfy the sonic and normal-edge conditions. The paper also discusses the physical meaning of the lower-order boundary solutions from the hub and tip.

  • Acoustic theory of the many-bladed Contra-Rotating Propeller: analysis of the effects of blade sweep on wake interaction noise
    Journal of Fluid Mechanics, 2019
    Co-Authors: Michael Kingan, A. B. Parry
    Abstract:

    An analytical model is presented for the wake interaction tones produced by a Contra-Rotating Propeller. We re-cast the usual far-field radiation formulae as a double integral over a nominal Propeller source annulus. Assuming that the number of blades on both Propellers is large, we evaluate the integral asymptotically in terms of its leading-order contributions from interior stationary or boundary critical points which represent the specific locations on the Propeller annulus that dominate the sound radiation. The asymptotic approach is powerful producing results in the form of one-line algebraic formulae that contain no integrals or special functions yet remain accurate. The asymptotics show that sweep is not necessarily beneficial and can cause the blade design to become critical for particular tones and directions in terms of a continuum of interior points distributed along a line on the Propeller source annulus producing a higher-order result and thus an enhanced radiated sound field. The paper also shows how the interior points are completely consistent with the sub- or super-critical gust response of a swept blade. Tones with low and zero azimuthal mode order are treated as special cases and the asymptotics show that, as the mode order reduces, the radiated sound becomes concentrated around the flight axis where even higher-order solutions are possible, including rings and annuli of stationary points around the Propeller annulus. Full numerical calculations confirm the accuracy of the asymptotic approach.

Janusz Piechna - One of the best experts on this subject based on the ideXlab platform.

  • Contra‐rotating Propeller for fixed wing MAV: part 2
    Aircraft Engineering and Aerospace Technology, 2013
    Co-Authors: Jacek Mieloszyk, Cezary Galiński, Janusz Piechna, Jacek Brzozowski
    Abstract:

    Purpose – This is the second of two companion papers presenting the results of research into a contra‐rotating Propeller designed to drive a super manoeuvrable micro air vehicle (MAV) and is devoted to the experimental results. The first paper presented the design process and numerical analyses.Design/methodology/approach – Most of experiments were conducted in the wind tunnel. Both contra‐rotating and conventional Propellers were tested. The test procedures and equipment are described first. The attention is focused on the design of an aerodynamic balance used in the experiment. Then, the measurement error is discussed, followed by presentation of the wind tunnel results. Finally, an initial flight test of the MAV equipped with contra‐rotating Propeller is briefly described.Findings – Wind tunnel experiment results fall between theoretical results presented in the first part of the paper. The application of contra‐rotating Propeller allowed to develop the propulsion system with zero torque. Moreover, the...

  • Contra‐rotating Propeller for fixed wing MAV: part 1
    Aircraft Engineering and Aerospace Technology, 2013
    Co-Authors: Jacek Mieloszyk, Cezary Galiński, Janusz Piechna
    Abstract:

    Purpose – This is the first of two companion papers presenting the results of research into a contra‐rotating Propeller designed to drive a super manoeuvrable micro air vehicle (MAV). The purpose of this first paper is to describe the design process and numerical analyses. The second paper is devoted to the experimental results verifying the computations.Design/methodology/approach – Software based on the analytical formulas derived by Theodore Theodorsen was used in the design procedure. Three‐dimensional finite‐volume simulation, performed with the use of commercial software verified the results. Finally, two‐dimensional simulation was conducted to explore the effect of the Propeller‐wing interaction. The meshes applied in these analyses are described.Findings – Propeller geometry received as a result of the design procedure is presented. The computation results for different turbulence models applied are discussed. Time dependent characteristics of contra‐rotating Propeller are presented as well as con...

Jacek Mieloszyk - One of the best experts on this subject based on the ideXlab platform.

  • Contra‐rotating Propeller for fixed wing MAV: part 2
    Aircraft Engineering and Aerospace Technology, 2013
    Co-Authors: Jacek Mieloszyk, Cezary Galiński, Janusz Piechna, Jacek Brzozowski
    Abstract:

    Purpose – This is the second of two companion papers presenting the results of research into a contra‐rotating Propeller designed to drive a super manoeuvrable micro air vehicle (MAV) and is devoted to the experimental results. The first paper presented the design process and numerical analyses.Design/methodology/approach – Most of experiments were conducted in the wind tunnel. Both contra‐rotating and conventional Propellers were tested. The test procedures and equipment are described first. The attention is focused on the design of an aerodynamic balance used in the experiment. Then, the measurement error is discussed, followed by presentation of the wind tunnel results. Finally, an initial flight test of the MAV equipped with contra‐rotating Propeller is briefly described.Findings – Wind tunnel experiment results fall between theoretical results presented in the first part of the paper. The application of contra‐rotating Propeller allowed to develop the propulsion system with zero torque. Moreover, the...

  • Contra‐rotating Propeller for fixed wing MAV: part 1
    Aircraft Engineering and Aerospace Technology, 2013
    Co-Authors: Jacek Mieloszyk, Cezary Galiński, Janusz Piechna
    Abstract:

    Purpose – This is the first of two companion papers presenting the results of research into a contra‐rotating Propeller designed to drive a super manoeuvrable micro air vehicle (MAV). The purpose of this first paper is to describe the design process and numerical analyses. The second paper is devoted to the experimental results verifying the computations.Design/methodology/approach – Software based on the analytical formulas derived by Theodore Theodorsen was used in the design procedure. Three‐dimensional finite‐volume simulation, performed with the use of commercial software verified the results. Finally, two‐dimensional simulation was conducted to explore the effect of the Propeller‐wing interaction. The meshes applied in these analyses are described.Findings – Propeller geometry received as a result of the design procedure is presented. The computation results for different turbulence models applied are discussed. Time dependent characteristics of contra‐rotating Propeller are presented as well as con...

Dokwan Hong - One of the best experts on this subject based on the ideXlab platform.

  • Design and Characteristics Analysis of Coaxial Magnetic Gear for Contra-Rotating Propeller in Yacht
    IEEE Transactions on Industrial Electronics, 2020
    Co-Authors: Homin Shin, Jung-hwan Chang, Dokwan Hong
    Abstract:

    In this article, the design and characteristic research of the coaxial magnetic gear for the Contra-Rotating Propeller in the premium yacht are presented. The scale-down model of 1/25 is reviewed as the research of the applicability of the coaxial magnetic gear. The space harmonic characteristics of the magnetic field in the coaxial magnetic gear with the low gear ratio from 1 to 2 are investigated, and the optimized models with the surface-mounted permanent magnet and quasi-Halbach array are obtained using the response surface method. In the several operating points of the diesel engine, the magnetic loss and the resultant thermal characteristics are analyzed and compared in each model. Finally, the desired coaxial magnetic for the Contra-Rotating Propeller in the premium yacht is achieved.