Abstract
This experimental study considers a single, axially aligned, jet in a rotating system. The injection is driven over a wide parameter range; from laminar (Re = 70) to turbulent (Re = 1116), and the rotation rate extends to 40rpm (Ek = 0.0033). A model is proposed which describes the system, and scaling arguments are presented which are compared to the experimental results. The study validates the presence of two unsteady phenomena; inertial waves and the formation breakdown cycle. A novel method is proposed for the analysis ofinertial waves which is validated with an excellent agreement to the dispersion relation. The method allows for the approximate characterisation of the wavelength and there is a clear agreement with the length scale proposed in the model. The formation breakdown cycle, which has previously only been observed at low rotation rates, is observed over the full range of rotational velocities investigated in the current study. The proportionality of the formation-breakdown frequency to the rotational frequency is confirmed to extend over
the entire, extended range of parameters. The formation breakdown frequency is found to be weakly influenced by the Reynolds number and this relationship is quantified within the available parameter range. The steady structure of the jet is documented and a full range of velocity profiles are explored where inertia and Coriolis forces compete. Coriolis induced cyclonic swirl is observed near the injection point due to entrainment, and Coriolis induced anti-cyclonic swirl is observed in regions further from the jet due to its radial expansion. The radius of the jet structure, restricted by the Coriolis force, is considerably reduced compared to the non-rotating jet and is determined to scale in accordance with the proposed model.
| Date of Award | May 2024 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Alban Potherat (Supervisor) & Peter J. Thomas (Supervisor) |