Dynamical stability analysis of a hose to the sky

The Stratospheric Shield was proposed as a geoengineering concept to control the Earth's climate and reverse global warming. This approach seeks to release sulphur dioxide (SO2) aerosols in the stratosphere to decrease the amount of sunlight that reaches the surface of the Earth. It was proposed that this can be done by pumping liquefied SO2 from the ground to the stratosphere in a 30 km long hose supported by aerostats.In this paper we evaluate the dynamic stability of a hose to the sky considering distributed supportive aerostats and an atomiser nozzle that forces a radial discharge of the fluid at the free end of the pipe. We modelled the pipe as a taut string conveying fluid using the finite element method.With a nozzle that discharges the flow straight through, we found that the pipe loses stability by buckling when the tension becomes null at least at one location along its length. This instability can be avoided by having a sufficient minimum tension T0 throughout the whole length of the pipe. The distribution of aerostats does not influence this instability but it modifies the mode shapes and affects the complex frequencies. The atomiser discharging the flow radially at the tip of the pipe has for effect to remove the possibility of an instability; its use is thus recommended. Moreover, we showed that the Coriolis damping can be significant and that by appropriately selecting the number of aerostats as well as the dimensionless flow velocity, stability can be increased. With this in mind, a functional hose to the sky could be designed to maximise Coriolis damping and thus passively damp the motion of the pipe due to forcing from the wind.

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