CUED Publications database

Dynamics and stability of variable-length, vertically-traveling, heavy cables: Application to tethered aerostats

Mukherjee, D and Sharma, I and Gupta, SS (2019) Dynamics and stability of variable-length, vertically-traveling, heavy cables: Application to tethered aerostats. Journal of Aircraft, 56. pp. 68-84. ISSN 0021-8669

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Abstract

The dynamics and stability of variable-length vertically traveling, heavy cables with an end load are investigated. Such cables act as tethers in aerostat systems. The cable is modeled as a heavy string undergoing small, planar vibrations while attached to a rigid, spherical aerostat. Aerodynamic and buoyancy forces act only on the aerostat. An asymptotic analysis for slow deployment rates provides excellent leading-order approximation to the dynamics, which is also obtained from finite element simulations. Stability of the aerostat system is then investigated computationally by considering the linear stability of the system when it is perturbed from its nominal dynamical state at any given time. It is found that, when an aerostat ascends, the cable always goes unstable after a certain time through a divergence instability. In contrast, flutter instability is found in the cable during the aerostat's descent. These stability analyses help in the development of deployment charts that relate the maximum achievable elevation to deployment rate. Such deployment charts can help in parameter selection for efficient aerostat deployment. The dynamics of the aerostat in the presence of spatiotemporally varying aerodynamic forces are also studied computationally. The paper concludes with two case studies of aerostat deployment that demonstrate the utility of the current analysis.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div C > Materials Engineering
Depositing User: Cron Job
Date Deposited: 17 Mar 2021 20:03
Last Modified: 06 Apr 2021 01:44
DOI: 10.2514/1.C034931