Ü Perferences | Database | Approximation functions

 

CFturbo uses many approximation functions. These functions are based on published measurement data that facilitate the forecast of optimal or accessible values.

 

In this dialog the approximation functions are displayed graphically and can be customized. Functions for the following physical quantities are available:

 

Impeller

 

Pump, Ventilator impeller

 

Pump impeller

 

Ventilator impeller

 

Compressor impeller

 

Turbine rotor

 

Stators

 

Volute

 

On the left at File location, the name of the file is shown that contains all data of the functions. In general this file is called Functions.cftfu, and is located in the installation directory of CFturbo. Modifications to functions are saved automatically if you leave the dialog window by pressing the OK-button. In case the user has no write permissions one could choose a different directory to save the file. Renaming files is possible by using the Save as-function. By clicking the Open-button a previously saved functions file can be opened.

 

 

 

All available functions are listed in a tree structure in the panel Functions left from diagram, sorted by machine type.

 

The user must first select the variable under the corresponding machine type. CFturbo’s internal function is displayed in the diagram in blue color. You can add any user defined function for each variable. Selected function is displayed in the diagram in addition to CFturbo's internal function. Function with active check box is used by CFturbo for calculations. If no function has active checkbox or no additional function is defined at all, then the CFturbo internal function is used.

 

 

The following hierarchy exist in the tree:

 

Functions can depend on 2 variables whereas one serves as parameter. Separate curves exist for each particular parameter value that are used to calculate function values. The parameter value is displayed on endpoint of the curve in the diagram.

With the upper limit curve you can define a recommended range, which means an area that is defined by a higher and a lower limit.

 

 

In panel Points right from diagram you can edit curve points of selected function. You can add new points at the end of the table – the points are automatically sorted by x values. To remove a point you have to delete either x or y value.

 

 

 

On panel Test you can test the active function. Saving of values is possible by clicking OK-button.

Page url: http://www.cfturbo.com/fileadmin/content/manual/en/index.html?prefapprox.html