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Author: search.filters.author.Janardhanan, SheejaSubject: search.filters.subject.Aerostat shapes

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    Stability Derivatives of Various Lighter-than-Air Vehicles
    (MDPI, 2022-07-07) Sasidharan, Anoop; Velamati, Ratna Kishore; Janardhanan, Sheeja; Oruganti, Venkata Ramana Murthy; Mohammad, Akram
    An aerostat with a single tether is proposed for the application of wind measurements at low altitudes. In the current study, the aerodynamic model parameters (stability derivatives) of the aerostat are investigated based on a CFD-based approach. The static, as well as the dynamic stability derivatives of the aerostats are presented. The calculation of the dynamic stability derivatives involves the simulation of the oscillations of the aerostats in their axial direction (surge), the vertical direction (heave) and angular motions with respect to the lateral direction (pitch). A forced sinusoidal oscillation is used for the simulation of the aerostat, and one stable period of oscillation is taken for the derivatives’ extraction. Four different aerostats are considered for the current study with four different angles of attack. The Zhiyuan aerostat, HAA aerostat, NPL aerostat and GNVR aerostat are the aerostats considered for this study. The stability derivative results obtained for the four aerostats are analyzed and compared with respect to their geometrical features. From the static aerodynamic characteristics, the Zhiyuan aerostat shows better performance than the other aerostats in terms of the lift–drag ratio. The dynamic stability derivatives of the Zhiyuan aerostat suggest its application as the proposed low-altitude wind measurement system.
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    Estimation of stability derivatives due to translational motion of various LTA vehicles using CFD
    (Spingerlink, 2022-11-29) Sasidharan, Anoop; Velamati, Ratna Kishore; Janardhanan, Sheeja; Oruganti, Venkata Ramana Murthy; Mohammad, Akram
    In this paper, the aerodynamic model parameters (stability derivatives) of the aerostat are investigated based on a CFD-based approach. The stability derivatives due to the translational motion of the aerostat are considered for the analysis in this paper. The extraction of the stability derivatives involves the simulation of the oscillations of the aerostat along the vertical direction (heave motion) and axial direction (surge motion). A forced sinusoidal oscillation is used for the simulation of the aerostat, and one stable period of oscillation is taken for the derivatives extraction. Four different aerostats are considered for the current study with four different angles of attack. Zhiyuan aerostat, HAA aerostat, NPL aerostat and GNVR aerostat are the aerostats considered for this study. The stability derivative results obtained for the four aerostats are analysed and compared with respect to their geometrical features. The dynamic stability derivatives of the Zhiyuan aerostat suggest its superiority among the four aerostats considered.