Variable Mass
Variable mass.
Description
Block Variable Mass models a variable mass. This block can be used when modelling a fuel tank with a decreasing amount of fuel. The input port receives the instantaneous mass value at each time step throughout the simulation. To minimise solver errors, avoid discontinuities and abrupt changes in the input signal.
When the mass of a component changes, the inertia force acting on that component also changes:
where
-
- inertia force;
-
- variable mass;
-
- mass velocity.
If the input mass value is below the minimum mass value specified in the Minimum mass parameters, the block performs its calculations for the minimum mass. The force of inertia is calculated as:
where is the minimum mass.
The amount of motion of the block remains constant. In the absence of external forces, a decrease in mass leads to an increase in velocity. The amount of motion remains constant until an external force forces it to change.
Ports
Conserving
#
Flange
—
port connecting the unit to the network
translational mechanics
Details
A non-directional port that defines a time-varying mass transmission component.
| Program usage name |
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Input
#
Mass
—
variable mass, kg
scalar
Details
The input port on which the mass value is received.
| Data types |
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| Complex numbers support |
No |
Parameters
Parameters
#
Minimum mass —
minimum weight
g | t | kg | mg | oz | lbm | slug
Details
The minimum value that a variable mass can take during a simulation.
If the input mass value is lower than the minimum mass value, it is set equal to the minimum mass value.
| Units |
|
| Default value |
|
| Program usage name |
|
| Evaluatable |
Yes |