The "Turbo-Pro" utility allows now the professional description of compressor and turbine using their thermodynamic characteristic maps.  Transient situation may be calculated, where the acceleration of the turbo shaft is evaluated, as the user may enter different start up conditions for the turbocharger in terms of initial gas state conditions at compressor and turbine ports and in terms of initial turbo shaft speed. In the case of a limited load pressure, SIMOTTO will control automatically the compressor outlet pressure by a compressor waste-gate or by controlling the turbine waste-gate. If the turbine waste-gate is used, SIMOTTO will inform the user about its controlling strategy, by plotting the history of the evolution of the amount of the opening of the waste-gate section.

The displayed diagram plots the pressure time histories for the turbo charged engine running at 4000 rpm and where the load pressure is controlled to be 2.0 bar.  The load pressure is controlled using the turbine waste-gate.

Note, that the pressure drop due to the intercooler is although taken into account.

The following diagrams show the time histories of the load pressure (outlet pressure of the compressor), of the turbine inlet or back pressure, of the turbo speed and finally of the controlled turbine waste gate section diameter for different engines speeds: 4000, 6000 and 8000 rpm.

The desired load pressure is in any case equal to 2.0 bar.

Note the over tuning of the load pressure between cycle 25 and 75 for an engine speed equal to 4000.

At 8000 rpm, the desired load pressure of 2.0 bar could not be achieved.

Note the pressure irregularities between cycle 25 and 50 at engine speed equal to 6000 rpm.  These are due to the sudden waste gate closures, which have been executed to prevent the turbo charger to completely loose power.

The diagram indicates, that the turbo charger reaches, in the case where the engine is running at 8000 rpm, its  maximum allowed speed of 250.000 rpm and then stays at this level.

Note the sudden waste gate  closures between cycle 25 and 50 for engine speed of 6000.  This have been executed by the waste gate controller to prevent the turbo to loose completely his power during transient state.

Note although, that at engine speed equal to 8000 rpm, the waste-gate remains closed during all the time.