Simulation of Subcritical Vibrations of a Large Flexible Rotor with Varying Spherical Roller Bearing Clearance and Roundness Profiles
Round 1
Reviewer 1 Report
The paper brings a method to simulate rotors supported by roller bearings and compares the obtained results with measurements in a test rig. The conclusions bring attention to the need of considering 3rd and 4th harmonics already in the design phase of large rotors. This is a relevant topic because, as mentioned, typically only the 2nd harmonic is considered in the design phase.
The paper is well written and well structured. There are only minor comments to be addressed.
I suggest adding something in the title to say that this paper is about spherical roller bearings.
Page 2, line 61 and 70: add a comma to separate both references inside the square brackets.
Page 4, Equation 2: In the first line, it seems to me that A0sin(phi0) is the z position of Oout. For the position of the roller, routby-dr-(Cd/4) should be used instead of A0. The same apply for the second line.
Page 4, line 140: Please add the definition of loaded distance.
Page 6, Figure 2: Please describe all the parameters from the table I the text. Many of them are not present in the picture, some that are in the picture cannot be clearly understood (for example: k, r1, r2 and d3).
Page 8: There are many details of the bearing support, but I miss the dimensions of the rotor. In figure 7, is the small number 4 the length of the rotor?
Page 9: I would use 18x10^6 N/m instead of 18 MN/m, but it is up to the authors.
Page 17: I suggest using the same scale span for both graphics in the Y axis. The way it is presented, it seems that the critical speed for the vertical direction change a lot, when in fact, they do not.
Page 19: The conclusions are well written, but I miss one graph summarizing the fact that considering the 3rd and 4th harmonics is important for the analysis of rotors supported by roller bearings. This graph could have the harmonics in the X axis and the amplitude in the Y axis, and one curve for each of the 5 cases studied. There could be 2 separated graphs (so that they are not too polluted), one with experimental data and one with simulated data. Also, do not forget to use the same scale in the Y axis of both graphs for ease of comparison. I think these graphs would add value to the final conclusions.
Author Response
Please see authors replies to reviewers in attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors present an interesting study on the impact of both the bearing waviness profile and clearance on the subcritical vibration excitation.
The content is being presented in a very concise form and thus, increasing the respective impact of readability.
The measurement as well as the simulation set up has been described in an efficient manner, focusing on the most relevant information required in order to comprehent the article's ontent.
Some questions have arisen and the authors are requested to give their feedback
- l. 166-168: can the assembly or disassembly process Impact other geometrical / kinematic parameters apart from radial clearance? Is the system bounded to axial clearance? If yes, what is the dependency to the radial clearance? How does the assembly process influence the aforemenioned pair? Is Mounted End Play a parameter relevant in such systems?
- pros and cons of timoshenko/FEM vs. multibody using flex body generation?
- l. 204: overhanging part --> does this lead to backward mode excitation? other mode excitation?
- are there any sub-sync effects observed? can they be captured with the current modeling? how does the waviness profile and bearing clearance affect such sub-synchronous vibrations (if at all apparent in such Systems)?
- l. 236: free-free verification? represents reality? stiffness changes over rpm, etc. Please clarify.
- l. 271: is the vibration in axial direction of no interest? Please clarify
- l 391:why is there a change in the critical speed with increasing clearance only in the horizontal direction? Please clarify.
Author Response
Please see authors replies to reviewers in attachment.
Author Response File: Author Response.pdf
