gsphelp  Component maps

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gsphelp  Component maps

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GSP applies tabular component characteristic maps to determine the relations among up to 5 component operating point parameters. The maps are stored in separate files, or alternatively can be stored embedded, and are compatible with the GasTurb [1] format. The operating point parameters are corrected for standard conditions in order to make the characteristic relations independent of the component inlet conditions. One or more of the following 5 parameters generally are used for component characteristics :

corrected mass flow

corrected rotational speed

pressure ratio

component efficiency

Reynolds index
The Reynolds index is generally omitted since it only has a relatively small effect on component performance. However, Reynolds correction factors may be specified in the map table based on the Reynolds index.

 

Pressure ratio (or relative pressure loss) and corrected entry mass flow are often used as map parameters. Corrected rotational speed and isentropic efficiency only are related to turbo machinery (i.e. compressors, fans and turbines). Up to three map input parameters (including the Reynolds index) are used to define the map operating point and determine the other map output parameter values.

 

Tabular characteristics can be scaled in order to be able to use them for different gasturbines. If the parameter values of the map design point do not match those in the design point of the gasturbine to be modeled, scaling factors are determined during the design point calculation.

 

Corrected or reduced parameters are often used for representation of component characteristics and overall engine performance. The off-design component maps often use corrected parameter groups to represent corrected mass flow and corrected or referred speed. Full correction (dimensionless) includes the diameter of the gas turbine and the gas properties. When a single gas turbine is considered, the diameter is not important. The gas properties are important when the real gas effects are considered since gamma is dependent on the temperature and R is dependent on the gas composition.

 

Note: The default GSP installation copies all model and map (*.map) files to the GSP projects directory. Map filenames paths are relative to the GSP directory. Therefore, when copying models or project files, with the map location set to file, and maps from one computer to another, an error message can appear due to a change in path.