Transient simulations represent engine responses to variations in time of one or more operating conditions. Transient component performance is calculated using the quasi steady state approach with steady state component maps. The transient effects included in GSP are rotor inertia, volume and heat soakage effects and, if control system models are added, control system dynamics. Rotor inertia, directly affecting rotor speed acceleration rates, usually is the dominating factor for transient performance. Volume and heat soakage effects may be calculated for each gas path component but often are relatively small and therefore disabled. They only significantly affect performance in special cases such as recuperated cycles.
For GSP transient simulations, the input-time functions are specified using time-input tables in the Transient tab sheets in applicable component windows and in the Ambient conditions window. Run a transient series calculation by clicking Transient in the model window. For a transient calculation at least one component must have a transient input specified for a variable. This transient input and the time range define the simulating time range. If more than one input transient is specified, these inputs work simultaneously during simulation and the shortest time range determines the simulation end time. If successful, a result table showing the transient series data will appear and data can be presented graphically. Transient input tables may be deactivated using the Transient input activated check box. Click the Graph button to see a graphical presentation of the transient input table.