Aerodynamic characteristics of an aerostat under unsteady wind gust conditions

Anoop, S; Velamati, Ratna Kishore; Murthy, O. V. Ramana

doi:10.1016/j.ast.2021.106684

Cited by 10 publications

(8 citation statements)

References 17 publications

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“…∆P max ≤ ∆P limit (32) Constraint III: The center of gravity should be kept in the O b x b z b plane to ensure the lateral static stability of the airship [34]. The thicknesses of the insulation structures, at the symmetrical position, relative to the O b x b z b plane, should be the same.…”

Section: Optimization Methods Of Insulation Layer Configurationmentioning

confidence: 99%

Multidisciplinary Optimization of Thermal Insulation Layer for Stratospheric Airship with a Solar Array

Yang

et al. 2022

Aerospace

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Stratospheric airships with a solar array have demonstrated overwhelming superiority in many aspects, such as earth observation, meteorological survey, and communication relay. The solar array supplies sufficient power for the airship to be in flight for months, but excessive heat is also transferred to the airship, causing high overpressure of inner gas. However, the optimal arrangement of the insulation layer on the airship has not been investigated. The theoretical method, including the geometry, thermal, and energy models, is developed and validated. The distribution of the temperatures and power of the solar cells, with different installation angles on the curved surface, is investigated. The thickness of insulation layer has a significant effect on the solar output power and internal pressure of the airship. An optimized configuration of the insulation structure is proposed, in order to improve the total output energy of solar array. The optimized configuration of insulations helps to reduce the structural mass by 24.9% and increase the payload mass by 9%. Moreover, the optimized arrangement improves the output energy of solar array in a year, and the maximum improvement is 8.2% on the winter solstice. The work displays the optimization of the thermal insulation layer for the stratospheric airship with a solar array, in order to improve the everyday energy acquirement during flight in a year.

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Section: Optimization Methods Of Insulation Layer Configurationmentioning

confidence: 99%

Multidisciplinary Optimization of Thermal Insulation Layer for Stratospheric Airship with a Solar Array

Yang

et al. 2022

Aerospace

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“…Four different angles of attack were considered for this analysis. The angles of attack were selected based on the consideration that all the flight scenarios of the aerostat should be included [9].…”

Section: Static Aerodynamic Characteristicsmentioning

confidence: 99%

“…Such unsteady conditions will result in oscillations or vibrations in the respective axis [8]. The previous study performed by the authors was to analyze the aerodynamic performance of the aerostat undergoing various unsteady wind conditions, as presented in [9]. The current study is part of an investigation to develop a control system for the single tethered aerostat and payload assembly.…”

Section: Introductionmentioning

confidence: 99%

“…Stability derivatives that are necessary for a longitudinal dynamic model of the considered aerostat were extracted by applying a translational forced sinusoidal oscillation in the vertical and axial directions and angular oscillations with respect to the lateral axis. In a previous study, the authors investigated the effect of the unsteady motion of the aerostat on the stability derivatives [9]. The current paper considers a steady wind formulation for the analysis.…”

Section: Introductionmentioning

confidence: 99%

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Stability Derivatives of Various Lighter-than-Air Vehicles: A CFD-Based Comparative Study

Anoop

Velamati

Janardhanan

et al. 2022

Drones

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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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“…Due to advancements in digital computing technology, numerical CFD solvers are suitable for handling high-performance computations 16 – 19 . As the stability derivative extraction of aerodynamic structures is very expensive in terms of computational power, the research community is utilising numerical solvers for extraction 20 – 22 . The stability derivatives were calculated using a forced oscillation of the body.…”

Section: Introductionmentioning

confidence: 99%

Mathematical modelling of a single tethered aerostat using longitudinal stability derivatives

Sasidharan,

Velamati,

Mohammad

et al. 2024

Sci Rep

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Lighter-than-air (LTA) aerial vehicles such as airships and aerostats can be found in various strategic and commercial applications, primarily due to their capability to hover and stealth. The mathematical model of these vehicles helps in understanding their complex dynamics and designing and developing proper stabilisation systems for them. Stability derivatives have been used for developing mathematical models for heavier-than-air aerial vehicles since their introduction. This paper presents a methodology to develop a mathematical model of an aerostat based on stability derivatives. One of the major contributions of this study is the estimation of aerostat’s added mass terms expressed as longitudinal stability derivatives due to acceleration of the longitudinal motion variables. A longitudinally decoupled linear mathematical model of a single-tethered aerostat using stability derivatives is investigated in this study. A computational fluid dynamics (CFD)-based analysis of the 3D model of the vehicle is used to obtain the stability derivatives. The methodology presented considers the aerostat and tether models separately before coupling them to create the full model. The stability derivative analysis is carried out using ANSYS Fluent, and the coupled tethered aerostat model is investigated using MATLAB 2020. The negative pitch angle of the aerostat is caused by the selection of the pitching centre as the aerostat centre of volume instead of the tether confluence point. The tension force on the tether, which is proportional to the wind velocity, and aerostat velocity components are found to be stabilised within 200–400 s.

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Aerodynamic characteristics of an aerostat under unsteady wind gust conditions

Cited by 10 publications

References 17 publications

Multidisciplinary Optimization of Thermal Insulation Layer for Stratospheric Airship with a Solar Array

Multidisciplinary Optimization of Thermal Insulation Layer for Stratospheric Airship with a Solar Array

Stability Derivatives of Various Lighter-than-Air Vehicles: A CFD-Based Comparative Study

Mathematical modelling of a single tethered aerostat using longitudinal stability derivatives

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