Problem statement (scenario):
A rigid rotor, 600 lbf (272 kgf), supported on a pair of bearings and a flexible rotor (massless elastic shaft with a point mass 600 lbf (272 kgf) at mid span) supported on bearings will be given. You consider to use 1) plain cylindrical bearing, 2) two pad bearing, 160 degree each, 3) three pad bearing, 100 degree each, and 4) four pad bearing, 70 degree each for each rotor system. All pad bearings have dimensionless preload = 25% and offset = 50% and include the bearing geometry. Operating conditions for the plain bearing geometry will be given. You will utilize a commercial rotordynamics software (XLRotor or DyRoBeS) for this project to calculate the damped eigenvalues (damped natural frequency and damping ratio vs shaft speed) and threshold speed of instability (if applicable).

- Please Model different bearing configurations:
a) elliptical, b) three pad, c) four pad, and d) five pad with various preloads [in dimensionless form: r = 1/3, 1/2, and 2/3] and pad offsets ranging from 0.50 to 0.80.
- Calculate the static and dynamic bearing performance characteristics,
- Graph the journal eccentricity, attitude angle, coefficient of friction, equivalent stiffness, whirl frequency ratio (WFR) versus the Sommerfeld number.

- Determine the imbalance response and note peak values and important variations in critical speed or any other item of interest.

- Present graphs showing these calculated parameters versus bearing configuration studied (for example- bar plots).

The objectives of the current group project are as follows:
- Problem statement

- Literature review about fundamentals of each bearing configuration

- Present a technical report detailing your findings according to the problems given above.

- Which bearing geometry gives the largest (minimum) film thickness and lowest friction coefficient, the smallest response to imbalance, the one with the highest threshold speed of instability?

- How does the WFR change for the bearing configurations studied?

* Please do NOT RUN all configurations described. I expect you to use common sense, engineering reasoning, etc.
 

Rules for Group Formation and Weekly Presentation
- 4~5 students/group
- Group presentation for group assignments: 30 minutes for each group, 20 minute for discussion
- Total #s of Slides: 30 pages
The weekly presentation must show the 1) Problem statement, 2) Goal, 3) Brief introduction, 3) Justification/Motivation, 4) Scope, 5) Tasks, 6) Methodology, and 7) Schedule for the project. Recall Template for weekly task plan.

Need more information about literature review?

- See Guideline for Literature Review

- https://writingcenter.tamu.edu/Grads/Writing-Speaking-Guides/Alphabetical-List-of-Guides/Academic-Writing/Literature-Reviews

- https://youtu.be/9la5ytz9MmM

1. Introduction to Hydrodynamic Lubrication

2.  Reading Assignment 1 (Due: Week 3): Summarize Chapters 6.1 and 6.2 (pp. 189-198)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition".

→ Submit ppt summary (personal HW)

http://rotorlab.tamu.edu/me626/Notes_pdf/Notes02%20Classical%20Lub%20Theory.pdf

 
• Week 6 (Oct. 11, 2022)

1. Special lecture 2 taught by student, Jihan Kim, regarding Rotordynamics (Ref. Machinery Vibration and Rotordynamics, Chap. 3 pp. 71-85 & Chap. 4 pp. 119-135)

2.  Reading Assignment 2 Review

3.  Reading Assignment 4 (Due: Week 7): Summarize Chapters 5.1 through 5.4 (pp. 161-173)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition". → Submit ppt summary (personal)

• Week 7 (Oct. 18, 2022)

1. Special lecture taught by student, Chanwoo Lee, regarding Thrust Bearings (Refs. Applied Tribology Chap. 7 & Practical Rotordynamics and Fluid Film Bearings Chap. 3.12/Chap. 4.6)

5.  Reynolds equation for laminar flow bearings: http://rotorlab.tamu.edu/me626/Notes_pdf/Notes05%20Lects_JBs_and_rotdyns%20presentation%2010.pdf

6. Reading Assignment 5 (Due: Week 8): Summarize Chapters 5.7 through 5.9 (pp. 179-186)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition". → Submit One-page summary (personal)

• Week 8 (Oct. 25, 2022)

1.  Reading Assignment 3 Review

2. Chapters 8.2 through 8.6 (pp. 260-269)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition".

3. Reading Assignment 6 (Due: Week 10): Tilting pad bearings, Squeeze film dampers → Submit One-page summary (personal)
    - Tilting Pad Bearing Design (J. C. Nicholas)
    - Design and Application of Squeeze Film Dampers in Rotating Machinery (F. Y. Zeidan, L. San Andres, and J. M. Vance)

1. Special lecture taught by student, Kyuman Kim, regarding Hydrostatic Bearings (Refs. Applied Tribology Chap. 10 & Practical Rotordynamics and Fluid Film Bearings Chap. 4)

2. Chapters 8.7 through 8.10 (pp. 269-276)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition".

3. Reading Assignment 7 (Due: Week 12): Parameter Identification → Submit One-page summary (personal)
    - Identification of Dynamic Bearing Parameters: A Review (Tiwari et al.)

• Week 10 (Nov. 08, 2022)

1. Special lecture taught by students, Hyunsung Jung & Homin Lim, regarding Turbulent Effect on Bearing Lubrication

2.  Chapters 8.11 through 8.13 (pp. 276-287)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition".

3. Reading Assignment 8 (Due: Week 14): Parameter Identification → Submit One-page summary (personal)
    - A Review of the Experimental Estimation of the Rotor Dynamic Parameters of Seals (Tiwari et al.)

• Week 11 (Nov. 15, 2022)

1. Special lecture taught by student, Junwon Heo, regarding Tilting Pad Journal Bearings (Refs. Practical Rotordynamics and Fluid Film Bearings Chap. 3.9 & Machinery Vibration and Rotordynamics pp. 185-208)

2. Chapter 8.16 (pp. 300-304)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition".

3. Kinematics of motion in cylindrical journal bearings
4. Static load performance of plain journal bearings

• Week 12 (Nov. 22, 2022)

* Quiz

1. Special lecture taught by student, Minsoo Wee, regarding Squeeze Film Dampers (Refs. Practical Rotordynamics and Fluid Film Bearings Chap. 3.10 & Rotordynamics of Turbomachinery - Vance pp. 234-249)

1. Dynamics of a simple rotor-fluid film bearing system

2. Physical interpretation of dynamic forces for circular centered whirl

3. Hydrodynamic fluid film bearings and their effect on the stability of rotating machinery

• Week 13

* Quiz

1. Special lecture 3 taught by student, Jihan Kim, regarding Rotordynamics (Ref. Machinery Vibration and Rotordynamics, Chap. 3 pp. 71-85 & Chap. 4 pp. 119-135)

2. Review: Chapter 8.7 (pp. 269-270)  in "Applied Tribology: Bearing Design and Lubrication, Third Edition".

3. Liquid cavitation in fluid film bearings

4. About cavitation

  1) https://youtu.be/U-uUYCFDTrc

  2) https://youtu.be/K_w3gcvA87I

• Week 14

1. Group project presentation

2. Space Tribology

  1) Design Guide for Bearings Used in Cryogenic Turbopumps and Test Rigs:

 https://ntrs.nasa.gov/api/citations/20200000047/downloads/20200000047.pdf?attachment=true

  2) Small, high-speed bearing technology for cryogenic turbo-pumps: https://ntrs.nasa.gov/api/citations/19750003277/downloads/19750003277.pdf

  3) SSME turbopump technology improvements via transient rotordynamic analysis:

 https://ntrs.nasa.gov/api/citations/19760009087/downloads/19760009087.pdf
  4) Advanced High Pressure O2/H2 Technology: https://ntrs.nasa.gov/api/citations/19850018551/downloads/19850018551.pdf

  5) Solid lubricants for the aerospace industry: https://www.stle.org/files/TLTArchives/2020/08_August/Solid_Lubricants.aspx

  6) Effective Application of Solid Lubricants in Spacecraft Mechanisms: https://doi.org/10.3390/lubricants8070074

• Week 15

  Group project presentation: Review

• Week 16

  Final Exam

------------------------

• 2020 Mid-term Project Presentation: EzTomas Review - Personal Presentation (each student presents the progress of the project)

• Group project before 2020

1. Read and study the work instructions and manuals (long and short) of the RK4 Rotor Kit.
 

2. Measure the dimensions and masses of all the rotating components and bearings of the Rotor Kit.
 

3. Calibrate the eddy current sensors.
 

4. Assemble the Rotor Kit with Prof. Keun Ryu. DO NOT assemble and/or disassemble the Rotor Kit unless directly instructed to do so.
 

5. Learn usage of 1) IOTech 652u and EzTOMAS DAQ and 2) Data Logger (GL840-WV and its manual) DAQ systems. (1-5: Due on Week 10 - Group)
 

6. Perform coastdown measurements of rotor supported for increasing supply oil pressures and temperatures. Students must measure the shaft diameter and bearing diameters after each test is completed. (Due on Week 12 - Group)
 

7. Prepare technical presentation on the results.   (6-7: Due on Week 14 - Group)

 1) The presentation must include

  - description of the test rig and bearings including dimensions;

  - description of the major test results supported by Bode (both with and without slow roll compensation) and Waterfall plots (See Ref. 1, pp. 13-21);
  - identification of damping ratios and critical speeds (See Ref. 2, pp. 18-22);

  - whirl and whip characteristics (See Ref. 3, pp. 39-42); and

  - conclusions.

    Refer the articles taken from Bently Nevada Orbit Magazine for more information about slow roll vibrations: Slow-Speed Vibration Signal Analysis, Understanding and Mitigating Shaft Runout.

 2) In the presentation, please report the rotor responses with the oil whirl and whip for various oil pressures and oil temperatures to determine their effects on bearing stiffness and damping coefficients.

   Note that oil whirl and whip are important instability phenomena associated with rotors supported by fluid film bearings. (See some examples: https://youtu.be/Mw0kUVhKTo0)

    Useful data presentation references: Orbit Plots-Centerline Diagram

 3) In the presentation, please report the heavy and high spots with the measured phase angles. Refer "Rotor Balancing Tutorial" written by Kelm et al. 2016 Turbomachinery and Pump Symposia.

    I recommend you to read "Writing Technical Memos" and "What makes a good technical report?" written by Dr. Luis San Andres before you begin your task.