modelCompressor
Extends from BaseClasses.CompressorBase (Gas compressor).
Information
This model adds the performance characteristics to the Compressor_Base model, by means of 2D interpolation tables.The perfomance characteristics are specified by two characteristic equations: the first relates the flow number phic, the pressure ratio PR and the referred speed N_T; the second relates the efficiency eta, the flow number phic, and the referred speed N_T [1]. To avoid singularities, the two characteristic equations are expressed in parametric form by adding a further variable beta (method of beta lines [2]).
The performance maps are thus tabulated into three differents tables, tablePhic, tablePR and tableEta, which express phic, PR and eta as a function of N_T and beta, respectively, where N_T is the first row while beta is the first column. The referred speed N_T is defined as a percentage of the design referred speed and beta are arbitrary lines, usually drawn parallel to the surge-line on the performance maps.
Modelica.Blocks.Tables.CombiTable2D interpolates the tables to obtain values of referred flow, pressure ratio and efficiency at given levels of referred speed and beta.
Modelling options
The following options are available to determine how the table is defined:
- Table = 0: the table is explicitly supplied as matrix parameter.
- Table = 1: the table is read from a file; the string fileName contains the path to the files where the tables are stored, either in ASCII or Matlab binary format.
References:
- S. L. Dixon: Fluid mechanics, thermodynamics of turbomachinery, Oxford, Pergamon press, 1966, pp. 213.
- P. P. Walsh, P. Fletcher: Gas Turbine Performance, 2nd ed., Oxford, Blackwell, 2004, pp. 646.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | explicitIsentropicEnthalpy (from CompressorBase) | true | isentropicEnthalpy function used |
| SI.PerUnit | eta_mech (from CompressorBase) | 0.98 | mechanical efficiency |
| Medium.Temperature | Tdes_in (from CompressorBase) | inlet design temperature | |
| Boolean | allowFlowReversal (from CompressorBase) | system.allowFlowReversal | = true to allow flow reversal, false restricts to design direction |
| SI.AngularVelocity | Ndesign | Design velocity | |
| Real[:,:] | tablePhic | fill(0, 0, 2) | Table for phic(N_T,beta) |
| Real[:,:] | tableEta | fill(0, 0, 2) | Table for eta(N_T,beta) |
| Real[:,:] | tablePR | fill(0, 0, 2) | Table for eta(N_T,beta) |
| String | fileName | "noName" | File where matrix is stored |
| TableTypes | Table | TableTypes.matrix | Selection of the way of definition of table matrix |
| Initialisation | |||
| Medium.AbsolutePressure | pstart_in (from CompressorBase) | inlet start pressure | |
| Medium.AbsolutePressure | pstart_out (from CompressorBase) | outlet start pressure | |
| Medium.Temperature | Tstart_in (from CompressorBase) | Tdes_in | inlet start temperature |
| Medium.Temperature | Tstart_out (from CompressorBase) | outlet start temperature | |
| Medium.MassFraction[Medium.nX] | Xstart (from CompressorBase) | Medium.reference_X | start gas composition |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| FlangeA | inlet (from CompressorBase) | ||
| FlangeB | outlet (from CompressorBase) | ||
| Modelica.Mechanics.Rotational.Interfaces.Flange_a | shaft_a (from CompressorBase) | ||
| Modelica.Mechanics.Rotational.Interfaces.Flange_b | shaft_b (from CompressorBase) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| ThermoPower.System | system (from CompressorBase) | System wide properties | |
| Medium.BaseProperties | gas_in (from CompressorBase) | ||
| Medium.BaseProperties | gas_iso (from CompressorBase) | ||
| Medium.SpecificEnthalpy | hout_iso (from CompressorBase) | Outlet isentropic enthalpy | |
| Medium.SpecificEnthalpy | hout (from CompressorBase) | Outlet enthaply | |
| Medium.SpecificEntropy | s_in (from CompressorBase) | Inlet specific entropy | |
| Medium.AbsolutePressure | pout (from CompressorBase) | Outlet pressure | |
| Medium.MassFlowRate | w (from CompressorBase) | Gas flow rate | |
| SI.Angle | phi (from CompressorBase) | shaft rotation angle | |
| SI.AngularVelocity | omega (from CompressorBase) | shaft angular velocity | |
| SI.Torque | tau (from CompressorBase) | net torque acting on the compressor | |
| SI.PerUnit | eta (from CompressorBase) | isentropic efficiency | |
| SI.PerUnit | PR (from CompressorBase) | pressure ratio | |
| Modelica.Blocks.Tables.CombiTable2D | Eta | ||
| Modelica.Blocks.Tables.CombiTable2D | PressRatio | ||
| Modelica.Blocks.Tables.CombiTable2D | Phic | ||
| Real | N_T | Referred speed | |
| Real | N_T_design | Referred design velocity | |
| Real | phic | Flow number | |
| Real | beta | Number of beta line |
Revisions
- 13 Apr 2005
by Francesco Casella:
New method for calculating performance parameters using tables. - 14 Jan 2005
by Francesco Casella:
Adapted to Modelica.Media. - 5 Mar 2004
by Francesco Casella:
First release.
Compressor model restructured using inheritance.