Tham khảo tài liệu 'rotating machinery vibration 2011 part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 308 Chapter 11 in Figs. 2 and 3 for the two other steam whirl cases presented in this chapter. Figure 4 reflects that bearing 1 was almost completely unloaded. Further computer analysis studies singled out an optimum solution to stabilize the Hz mode which resulted in stable operation up to the machine s rated output. Bearing 1 was replaced in the model with a four-pad tilting-pad journal bearing with a range of preload factors of which provided the best compromise. As a result of the author s analyses the plant replaced bearing 1 with a four-pad tilting-pad journal bearing having a preload factor of . This retrofit enabled full-load operation of the machine. 5. SUMMARY These cases and those of Chapter 10 demonstrate convincingly that adroit use of computer modeling drastically increases the probability of correctly diagnosing and curing difficult rotating machinery vibration problems that are not cured by routine maintenance actions or trial-and-error approaches. BIBLIOGRAPHY 1. SH Crandall. The physical nature of rotor instability mechanisms. In ML Adams ed. Proceedings ASME Applied Mechanics Division Symposium on Rotor Dynamical Instability AMD Vol 55 pp. 1-18 1983. 2. Electric Power Research Institute EPRI . Short Course. Proceedings. EPRI Symposium on Trouble Shooting Power Plant Rotating Machinery Vibrations. San Diego. May 19-21. 1993. 3. TH McCloskey. ML Adams. Troubleshooting power plant rotating machinery vibration problems using computational techniques. Fifth IMechE International Conference on Vibration in Rotating Machinery. Bath. England. September 1992. 12 Additional Rotor Vibration Problem Cases and Topics 1. INTRODUCTION The commonly identified rotor vibration root causes and symptom descriptions specific to each cause are summarized in Sec. 8 of Chapter 9. Chapters 10 and 11 present specific troubleshooting case studies which fall into two of the most frequently identified problem categories and which are drawn from the author s own .
