Taking a self-designed and developed radial inflow turbine which is suitable for organic Rankine cycle waste heat power generation as the research object

this paper analyzes the critical speed of the rotor system for the radial inflow turbine

by using the ANSYS Worbench and considering the gyroscopic effects

on the basis of replacing the bearing stiffness by spring. The results show that

the first critical speed of this rotor system is 1 273 r/min and the second order critical speed is 81 362 r/min. The working speed deviates from the critical speed to a certain extent

but with a reasonable safety margin. When the bearings stiffness increases

the critical speed increases sharply at first

and then turns slow

which is the tendency between critical speed and bearings stiffness

then the stiffness of the bearings in this system arrangement turns to be reasonable. The bearings span has a little effect on the critical speed. However

with the increasing shaft tail elongation

the critical speed keeps unchanged at first and then decreased rapidly.