EVALUATION OF INIT IAL DESIGN IDEAS DESIGN IDEA # 1~ Features & Functional Description: The design features a central floatation jacket, which acts as the core foundation for the attachment of the stabilising pontoons. It also helps to add to the initial buoyancy of the tower, by providing a large increase in the volume of waterdisplacement for a relatively small gain in weight.
This is then surrounded by four individual floatation pods, which can move freely up and down with the movement of the waves, but can also rotate through a slight angle back and forth about their longitudinal axes. The further out these pods sit from the centre, the stronger the effect they have of stabilising the tower. An upper ring is also connected by pistons, the purpose of which is to stabilise tilting and rocking motions by way of restricting the movement of the top-half of the tower. Again, the higher up this sits, the greater its stabilising effect.
A Gas-Transfer System also features as a potential option, in which the compression of one piston forces gas out of it, and into the piston on the opposite side, hence causing it to simultaneously expand by the same length, and at the same time. The result is that as the piston on one side raises, the piston on the other side lowers by the same distance. This serves to keep the tower upright: it stops the raising of one pontoon pushing the tower over, by way of extending a support to the other side and hence holding it up. 2~ Features & Functional Description: This design provides stabilisation in a much more omniscient manner, in the sense that supporting forces can be exerted from all directions, all at once or at any one time, indeed in any way necessary depending on the action of the waves at a given point in time. This is provided by the
STRENGTHS (+)
WEAKNESSES (-)
The four floatation pods are independent of each other, and so can move freely and randomly, accommodating the sporadic chaos of wave action on the North Sea.
The weight of these pistons is going to be huge, impeding on the probable buoyancy of the whole system.
The inner floatation ring of this design allows the tower to be held high out of the water, and hence alleviates previous concerns over the tower sinking if the lower base became submerged. This also reduces the risk of the tower striking the sea floor.
However, holding the tower and its Centre of Mass so high out of the water in this way may in fact have its implications. For one, it may make the tower quite unstable, with so much mass at the top being free to move. It also increases the size of the gap between the base of the tower and the sea floor. With further to fall, the tower will eventually hit the floor at a greater velocity, and hence experience larger, potentially damaging impact forces. Four floatation pods provide universal, Omni-directional stability, as mandated by the Specification.
Uniform, Omni-directional stability is again provided by the circular ring. The inner ring and damping pistons allow the tower to move about freely inside, but help to absorb the shocks and dramatic movements of the
They will also be exhaustive and costly in manufacture, both in time and in raw materials. With this implication already existing on such a phenomenal scale due solely to the size of the tower itself, we should really be looking to minimise these extra costs. The articulated joints will also be complex, and will need to be substantial so as to stand up to the intense stresses of the moving pistons.
As the outer floatation ring is effectively split into 4 separate sections, it may be slightly flimsy, so to speak, and if these pods shift by different amounts at different times, which they inevitably will, then the tower may be forced into precarious positions on the water. The Gas-Transfer System assumes that opposing floatation pods will shift alternately and uniformly, which clearly may not be the case. It is also intrinsically complex, and is likely to be another point of potential failure. With the tower hanging so low in the water, there is the obvious collision-risk in shallow waters.
More pistons are used here, which, needless to say, is detrimental in weight and complexity, though it is not
Engineering Education Scheme: The Report | Evaluation of Initial Design Ideas
25
