The Dynamics Study Of Rotor With Rod Bolt Fastening And Bearing

Rod fastening rotor is composed of each independent disk (wheel) shaft pressing together by the tension rod bolts, which make it become a complex structure of rotor. The structural design of the rotor due to the particularity, as well as light weight, high stiffness, high strength, easy to replace the wheel and other characteristics is widely used in heavy-duty gas turbines. So the study of dynamic characteristics of rod fastening rotor bearing system is very necessary.According to the structural characteristics of the rotor rod, through the rod corresponding rotor dynamic assumptions, the key consideration to frictional contact between the surface of the wheel and the rod bolt preload. This paper is based on theory of Herz surface contact and G-W model, and established the model of the wheel surface, and exported formulas equivalent bending stiffness. The whole rotor is discretized into a finite number of small units for finite element method. At the same time use of the software Matlab to compile program for calculate dynamic characteristics of the journal bearing oil film, through example shows that using method. Create complete rod fastening rotor-bearing system finite element model, use of the finite software ANSYS to analyze the rod fastening rotor’s modal with the pre-tightening force. Get its natural frequency and vibration mode. Study the pre-tightening force on the natural characteristic of rotor fastening rod in rigid support and elastic support under two conditions influence, the changes of rod’s speed have influence on calculate dynamic characteristics of the journal bearing oil film and natural characteristic of rod fastening rotor.The analysis revealed that the natural frequency of the distributed rotor rod increases with the increase of preload. And the natural frequency has a fast rise rate, when the preload is small, but the rate will turn down along with the increasing of the preload. The natural frequency of the rotor in a rigid support is greater than the elastic support. The study find that with the continuous improvement of the rotor speed, rigidity and damping coefficient of sliding bearing is declining. At the same time, the natural frequency of the rotor is also decreased.