The load torques include compressor stage power, gear power loss, oil pump, etc. Up to six loads can be input in the analysis. It is common to specify the load torque as a function of speed in percentage. The torques are input in their actual (true) values, not the equivalent torques. The program converts the true torques to the equivalent torques and performs the analysis. The output vibratory torque can be specified either in true or equivalent values.
where n is the speed ratio.
Following is an example for 3 stages compressor. All the data are entered in their actual values. Speed ratios must be entered in the Shaft Elements Tab to convert the data into the equivalent values. The speed ratios for the stage 1 to the driving shaft is 8.43, for the stage 2 to the driving shaft is 12.04, and for the stage 3 to the driving shaft is 16.85. The compressor is normally started with inlet valve closed, which is so called unloaded condition. At full speed, the total unloaded torque is about 25% of the full load torque.
Following is another example with all the loads lumped at one single station and all data are converted into the equivalent data already. No speed ratio is needed for this equivalent system.
See other Torsional/Axial Data Torsional/Axial Data.
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