.ThermoPower.Gas.Compressor

Information

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:

1. S. L. Dixon: Fluid mechanics, thermodynamics of turbomachinery, Oxford, Pergamon press, 1966, pp. 213.
2. P. P. Walsh, P. Fletcher: Gas Turbine Performance, 2nd ed., Oxford, Blackwell, 2004, pp. 646.

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.

Compressor model restructured using inheritance.
• 5 Mar 2004 by Francesco Casella:
  First release.