The GasTurb compressor map format

The GasTurb compressor map format utilizes a standardized text file layout with a .MAP extension containing four distinct tables to define performance. It structures the component performance through auxiliary coordinates called β-lines (Beta lines), which resolve ambiguity during numerical interpolation.

The detailed compressor map format is as follows: On the first line of a map data file there is the number 99 followed by a blank. After that the map header line follows on the same line. On the second line the Reynolds number correction factors on efficiency are given in the following form:

Reynolds: RNI=x1 f=y1 RNI=x2 f=y2

On the next line there is the keyword Mass Flow. On the line after this keyword the table for corrected mass flow begins. The first number on this line is the table key derived from the number of speed lines and the number of ß-lines in the map:

table key = (number of speed lines + 1) + (number of ß-lines + 1) / 1000

If there are 10 speed lines and 15 ß-lines, for example, the table key is 11.016. The first four β-values follow the table key. On the next lines are the rest of the ß-values listed, up to five numbers on each line.

The first number on the next line is the speed value for the first speed line. After that the first four mass flow numbers follow. The rest of the mass flow data for the first speed line appears on the following lines. Apart from the last line there are always five numbers on each line.

The rest of data follow in an ascending order of speed.

The keyword Efficiency marks the start of the second table which contains the isentropic efficiency data. The sequence and the format of the data follow the same pattern as the one described for the corrected mass flow.

Pressure Ratio is the keyword for the third table of a compressor map.

The keyword for the last table is Surge Line. The surge pressure ratio is given as a function of the corrected mass flow. The data are arranged in an ascending order by mass flow.