Weirs_abg.tex

MTT command:

mtt Weirs abg tex

Figure 4.1: System Weirs: acausal bond graph

The acausal bond graph of system Weirs is displayed in Figure 4.1 (on page ) and its label file is listed in Section 4.1.1 (on page ). The subsystems are listed in Section 4.1.2 (on page ).

Aircraft fuel tanks are often fitted with baffles to reduce fuel slosh. A simple model relating to such a system is shown in Figure 4.1 (on page ) which corresponds to a single tank containing two dividing weirs. Liquid with flow rate $f$ enters the left-hand compartment; liquid leaks out of the centre compartment at a flow rate determined by gravity and the properties of the corresponding orifice.

The Bond Graph appearing in Figure 4.1 (on page ) represents each of the three compartments by a C component (labelled tank1 to tank3), the corresponding pressures are measured by the SS elements p1-p3. The leak is represented by the R component labelled leak. The flows over the two weirs are represented by the four ISW components; each weir has a separate ISW component for each flow direction. Each ISW component is switched by the appropriate level.

The system was simulated for 20 time units and the resultant level of each tank partition is plotted in Figure 4.4 (on page ). Each partition has unit cross section, and the two weir heights are $1$ and $2$ respectively; the inflow $f$ is given by:

$$f = \begin{cases}1 & \text{if $t \le 10$}\\ 0 & \text{if $t > 10$} \end{cases}$$ (4.1)

and the leak resistance is linear with flow resistance 5.