Emmanuel Abaya

  • Department of Aerospace
  • Supervisors: Dr Brano Titurus
  • Project: Behaviour of horizontal axis fluid-based rotor balancers

Fluid based balancers (FBBs) are a passive means of balancing rotors during operation. They are very attractive as they have a relatively simple architecture and require no external energy to power them since they are driven by the whirling of the unbalanced rotor.

These balancers, however, have only seen successful industrial application on vertical axis washing machines which operate well above their first critical speed. This means that very little is known about their behaviour in a non-axisymmetric gravitational field or at subcritical and critical speeds.

In my project a fluid based balancer comprising an acrylic disk with an annular cavity was rigidly fixed to a simple test rig. The balancer was filled with varying quantities of fluid and the steady state response of the rotor due to an applied unbalance was observed.

I found that at the first critical speed of the rotor, accelerations were reduced by up to 30 percent with the use of the balancer. A circumferential surface wave, with a constant rate of propagation, for a given fluid volume, was shown to exist at a small range of supercritical rotor speeds. The wave manifests as an asynchronous steady state response which exhibits evidence of non-linear jump phenomenon normally attributed to duffing oscillators, with a switch from the stiffening variety to the softening variety with high fluid volumes.

Biography

After my first year at Bristol I secured an internship at GE Aviation’s MRO plant in Cardiff as an Engineering Operations Coordinator. Observing subtle but crucial design features and learning about the extreme and unimaginable operating environment of the gas turbines really captured my imagination.

I found the Vibrations 2 course very interesting in my second year. One of the things I love most about engineering is the ability to describe nature in a deterministic way and this was personally apparent in the structural dynamics discipline

The introduction of the Individual Exploratory Project in the third year gave me an avenue to explore my new interest in rotordynamics and lay the foundations for my Final Year Project.  I had the opportunity between my third and fourth year to work as a summer intern with the Rolls-Royce corporate rotordynamics specialist, Andy Rix who suggested the idea for my Final Year Project.

My year one tutor, Dr. Brano Titurus, who later became my supervisor was a very big positive influence and is an example of the incredible members of staff that students can rub shoulders with at Bristol.

I’ve thoroughly enjoyed my time at Bristol; the course cultivates you to be well rounded but also gives the flexibility to develop and pursue personal interests.

Emmanuel Abaya, Aerospace Engineering (MEng)
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