Nonrotating Beams Isospectral to Tapered Rotating Beams

Kambampati, Sandilya; Ganguli, Ranjan

doi:10.2514/1.j054126

Cited by 14 publications

(11 citation statements)

References 27 publications

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“…In that study, some additional parameters, that is, the blade twist and coefficients of the airfoil distribution function, were also investigated. After optimization, the required horsepower reduced by 7.4% and the figure of merit for hover improved by 6.5% (see also [8,9] for different blade taper applications). In addition to the previously mentioned studies, the effect of blade taper on the control effort of the flight control system of a helicopter was also studied by Oktay and Sal [10].…”

Section: Introductionmentioning

confidence: 99%

Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort

Oktay

Sal

2017

International Journal of Aerospace Engineering

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In this study, the effect of simultaneous variation in blade root chord length and blade taper on the control effort of helicopter flight control system (i.e., FCS) of a helicopter is investigated. Therefore, helicopter models (i.e., complex, control-oriented, and physicsbased models) including the main physics and essential dynamics are used. The effect of simultaneous variation in the blade root chord length and blade taper (i.e., in both chordwise and lengthwise directions dependently) on the control effort of an FCS of a helicopter and also on the closed-loop responses is studied. Comparisons in terms of the control effort and peak values with and without variations in the blade root chord and blade taper changes are carried out. For helicopter FCS variance-constrained controllers, specific output variance-constrained controllers are beneficial.

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Section: Introductionmentioning

confidence: 99%

Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort

Oktay

Sal

2017

International Journal of Aerospace Engineering

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“…Kambampati et al [15,16] found non-rotating beams isospectral to rotating uniform beams and rotating beams isospectral to axially loaded non-rotating uniform beams. Kambampati & Ganguli [17,18] found non-uniform beams and stiff springs isospectral to axially loaded uniform beams and piano strings, and non-rotating beams isospectral to tapered rotating beams. In their study, they used Barcilon–Gottlieb transformation to convert the fourth-order governing equation of one kind to the required one.…”

Section: Introductionmentioning

confidence: 99%

Isospectrals of non-uniform Rayleigh beams with respect to their uniform counterparts

Ganguli

2018

R. Soc. open sci.

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In this paper, we look for non-uniform Rayleigh beams isospectral to a given uniform Rayleigh beam. Isospectral systems are those that have the same spectral properties, i.e. the same free vibration natural frequencies for a given boundary condition. A transformation is proposed that converts the fourth-order governing differential equation of non-uniform Rayleigh beam into a uniform Rayleigh beam. If the coefficients of the transformed equation match with those of the uniform beam equation, then the non-uniform beam is isospectral to the given uniform beam. The boundary-condition configuration should be preserved under this transformation. We present the constraints under which the boundary configurations will remain unchanged. Frequency equivalence of the non-uniform beams and the uniform beam is confirmed by the finite-element method. For the considered cases, examples of beams having a rectangular cross section are presented to show the application of our analysis.

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“…Moreover, because of the reality that only applying blade taper is impractical from the viewpoint of decreasing the control effort of the FCS of a helicopter, an additional research study (Oktay and Sal (2017b)) for optimizing control effort of the helicopter, blade taper and blade root chord length were instantaneously restructured with the coefficients of the OVC-based helicopter FCS. Nevertheless, in previous studies (Ozdemir and Kaya, 2006;Ozdemir and Kaya, 2007;Hodges et al, 2008;Vu et al, 2013;Kambampati and Ganguli, 2016;Oktay and Sal, 2016a, 2016b, 2017a2017b), the design terms were in passive situation. In none of these research papers had not any actively morphing term.…”

Section: Introductionmentioning

confidence: 97%

Analysis of combined passively and actively morphing blade root chord length and blade taper for helicopter control

Sal

2019

AEAT

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Purpose The purpose of this study is to examine the effect of passive and active morphing of blade root chord length and blade taper on the control effort of the flight control system (FCS) of a helicopter. Design/methodology/approach Physics-based helicopter models, which are functions of passive and active morphing, are created and applied in helicopter FCS design to determine the control effort. Findings Helicopters, having both passively and actively morphing blade root chord length and blade taper, experience less control effort than the ones having either only passively morphing blade root chord length or only blade taper or only actively morphing blade root chord length and blade taper. Practical implications Both passively and actively morphing blade root chord length and blade taper can be implemented for more economical autonomous helicopter flights. Originality/value Main novelty of our article is simultaneous application of passive and active morphing ideas on helicopter root chord length and blade taper. It is also proved in this study that using both passive and active morphing ideas on helicopter blade root chord and blade taper causes much less energy consumption than using either only passive morphing idea on helicopter blade root chord and blade taper or only active morphing idea on helicopter blade root chord and blade taper. This also reduces fuel consumption and also makes environment cleaner.

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Nonrotating Beams Isospectral to Tapered Rotating Beams

Cited by 14 publications

References 27 publications

Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort

Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort

Isospectrals of non-uniform Rayleigh beams with respect to their uniform counterparts

Analysis of combined passively and actively morphing blade root chord length and blade taper for helicopter control

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