modelGasForce2
Rough approximation of gas force in a combustion engine's cylinder
Extends from Modelica.Mechanics.Translational.Interfaces.PartialCompliant (Compliant connection of two translational 1D flanges).
Information
The gas force in a cylinder of a combustion engine is computed as function of the relative distance of the two flanges. It is required that s_rel = flange_b.s - flange_a.s is in the range
0 ≤ s_rel ≤ L,
where the parameter L is the length of the cylinder. If this assumption is not fulfilled, an error occurs. The resulting approximation of the gas pressure is shown in the following figure and depends on both s_rel and the relative velocity v_rel = der(s_rel).
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Length | L | Length of cylinder | |
| SI.Length | d | Diameter of cylinder | |
| SI.Volume | k0 | 0.01 | Volume V = k0 + k1*(1-x), with x = 1 - s_rel/L |
| SI.Volume | k1 | 1 | Volume V = k0 + k1*(1-x), with x = 1 - s_rel/L |
| SI.HeatCapacity | k | 1 | Gas constant (p*V = k*T) |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Flange_a | flange_a (from PartialTwoFlanges) | (left) driving flange (flange axis directed into cut plane, e. g. from left to right) | |
| Flange_b | flange_b (from PartialTwoFlanges) | (right) driven flange (flange axis directed out of cut plane) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.Position | s_rel (from PartialCompliant) | Relative distance (= flange_b.s - flange_a.s) | |
| SI.Force | f (from PartialCompliant) | Force between flanges (positive in direction of flange axis R) | |
| Real | x | Normalized position of cylinder (= 1 - s_rel/L) | |
| SI.AbsolutePressure | press | Cylinder pressure | |
| SI.Volume | V | ||
| SI.Temperature | T | ||
| SI.Velocity | v_rel | Relative piston velocity (<0: compression; >0: expansion) |