Abstract: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) … Show more
“…Aerodynamic stability derivatives associated with the mathematical model of the aerostat are extracted using a CFD-based methodology 21 . The proposed methodology involves a small-amplitude periodic oscillation of the aerostat model with respect to the corresponding directions for which stability derivatives are needed.…”
Section: Mathematical Modelling Of the Tethered Aerostatmentioning
confidence: 99%
“…A sinusoidal oscillation is induced in the aerostat model, and the response of the model is collected for multiple time periods of the oscillation. One complete cycle of response is analysed using Fourier analysis 21 , 22 . Figure 3 A schematic representation of the methodology adopted for the stability derivatives estimation.…”
Section: Mathematical Modelling Of the Tethered Aerostatmentioning
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.
“…Aerodynamic stability derivatives associated with the mathematical model of the aerostat are extracted using a CFD-based methodology 21 . The proposed methodology involves a small-amplitude periodic oscillation of the aerostat model with respect to the corresponding directions for which stability derivatives are needed.…”
Section: Mathematical Modelling Of the Tethered Aerostatmentioning
confidence: 99%
“…A sinusoidal oscillation is induced in the aerostat model, and the response of the model is collected for multiple time periods of the oscillation. One complete cycle of response is analysed using Fourier analysis 21 , 22 . Figure 3 A schematic representation of the methodology adopted for the stability derivatives estimation.…”
Section: Mathematical Modelling Of the Tethered Aerostatmentioning
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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