This is the base model for the FanMech fan model.
The model describes a fan, or a group of Np identical fans, with optional blade angle regulation. The fan model is based on the theory of kinematic similarity: the fan characteristics are given for nominal operating conditions (rotational speed and fluid density), and then adapted to actual operating condition, according to the similarity equations.
In order to avoid singularities in the computation of the outlet enthalpy at zero flowrate, the thermal capacity of the fluid inside the fan body can be taken into account.
The model can either support reverse flow conditions or include a built-in check valve to avoid flow reversal.
Modelling options
The nominal flow characteristic (specific energy vs. volume flow rate) is given by the the replaceable function flowCharacteristic. If the blade angles are fixed, it is possible to use implementations which ignore the bladePos input.
The fan energy balance can be specified in two alternative ways:
Several functions are provided in the package Functions.FanCharacteristics to specify the characteristics as a function of some operating points at nominal conditions.
Depending on the value of the checkValve parameter, the model either supports reverse flow conditions, or includes a built-in check valve to avoid flow reversal.
If the in_Np input connector is wired, it provides the number of fans in parallel; otherwise, Np0 parallel fans are assumed.
It is possible to take into account the heat capacity of the fluid inside the fan by specifying its volume V at nominal conditions; this is necessary to avoid singularities in the computation of the outlet enthalpy in case of zero flow rate. If zero flow rate conditions are always avoided, this dynamic effect can be neglected by leaving the default value V = 0, thus avoiding a fast state variable in the model.
The CheckValve parameter determines whether the fan has a built-in check valve or not.
| Name | Description |
|---|---|
| Medium | Medium model |
| flowCharacteristic | Head vs. q_flow characteristic at nominal speed and density |
| FlowCharacteristicModel | |
| powerCharacteristic | Power consumption vs. q_flow at nominal speed and density |
| efficiencyCharacteristic | Efficiency vs. q_flow at nominal speed and density |