CHAPTER 2 VIBRATIONS, RESONATORS, AND STABILITY CONCEPTS

CHAPTER 3 FLUID DYNAMIC CONCEPTS

CHAPTER 8 ECCENTRICITY INSTABILITY OF TAINTER (RADIAL) GATES

CHAPTER 9 PRESSURE ON A SUBMERGED PLATE UNDERGOING STREAMWISE ROTATION

CHAPTER 10 THEORY OF SELF-EXCITED COUPLED-MODE VIBRATION OF TAINTER GATES

CHAPTER 11 MEASUREMENT OF COUPLED-MODE INSTABILITY ON MODEL SCALE

CHAPTER 12 WACHI DAM AND FOLSOM DAM - COUPLED-MODE INSTABILITIES

CHAPTER 13 ANALOGIES BETWEEN COUPLED-MODE GATE VIBRATION AND COUPLED MODE FLUTTER

CHAPTER 14 FULL-SCALE GATE MEASUREMENTS

CHAPTER 15 REFLECTIONS AND CONCLUSIONS

REFLECTIONS BY ISHII　回想録

I recall many moments in the past, both before and just after I started my life’s work on flow-induced vibration of hydraulic gates. I was a 3^rd year student at Osaka University when the 3^rd gate on Wachi Dam failed in 1967. Professor Emeritus Tokio Uematsu presented the details of this serious gate failure to us in our class in hydraulics. When I was in my first year as a Ph.D. student in 1971, my adviser, Professor Kensaku Imaichi, suggested that I investigate the Wachi Dam gate failure. I note with sadness the passing of Professor Imaichi earlier this year at 86 years of age.

Before I started my research efforts in flow-induced vibration, I was reading the German textbook Grenzschicht Theorie by H. Schlichting, in my quest for a topic for my dissertation. I was completely exhausted by reading about the breadth of the research work reported by Schlichting, and so many experimental projects to consider. Around the time I was overwhelmed by the difficulty of finding my dissertation topic among the topics in Schlichting’s book, Professor Imaichi’s suggestion to pursue the subject of the mechanism of flow-induced vibrations in the Wachi Dam gate failure was just like a message from God to help me. When I started to study flow-induced vibration problems in many books and journal papers, I was again exhausted by the multitude of so many experimental works.

One day I found, in a flash of inspiration, that a complete mathematical analysis might be possible for the type of flow-induced vibration involved in the Wachi Dam gate failure. Since the subject seemed to me to be quite independent of the non-linear hydrodynamic effects such as those caused by shedding vortices, I started to study many mathematical techniques from many books by Lord Rayleigh, H. Lamb, J. J. Stoker and others. I studied topics such as Fourier integrals and Fourier transforms, Laplace transforms, the Cauchy-Riemann complex integral theorem and so on. In addition, I studied intensely Rayleigh’s wave theory. As a result, I was able to identify theoretically the essential flow-induced dynamic instability that eccentric Tainter gates possess. I completed my dissertation and was awarded my Ph.D. degree from Osaka University in 1975.

I was very pleased with the recognition of my efforts when my research work was reported in the Asahi Newspaper on March 3, 1977. My initial joy at the newspaper report, however, changed to deep despair when is I experienced extraordinarily intense pushback and condemnation from several gate companies, which insisted that they did not construct eccentric Tainter gates. I was forced to stop my research on the dynamic instability of Tainter gates. At that time I could find no way forward with my research, except to change the focus from Tainter gates to long-span gates. With serious disappointment, I sought opportunities to go abroad and was fortunate to receive an Alexander von Humboldt Foundation fellowship for one year in Germany (West Germany, at the time) starting in November 1983. My host was Professor Eduard Naudascher in the Institute of Hydrodynamics at the University of Karlsruhe. It was in Karlsruhe where my future best friend in my life, Professor Charles W. Knisely, was waiting for me.

I suffered from stomach cancer in 1993 and was fortunate for early detection. Through surgical removal of the cancer, I was able to survive. I was greatly motivated to work on flow-induced vibrations after surviving this scare.

In the summer of 1995, the Japan Times reported the failure of the Number 3 gate at the Folsom Dam in California. I made quick contact with the USBR a few days after the gate failure and was asked to be a member of the Forensics Team. I restarted my investigation of the flow-induced vibrations of Tainter gates, thinking of what might have been the cause of the failure. I presented the details of the Folsom Dam gate failure to my third year undergraduates in their class on hydraulics at Osaka Electro-Communication University. To my great pleasure, one of my students in that class, Keiko Anami, expressed an intense interest in investigating the cause of the failure with me. She was able to easily master the difficulties of my previous theoretical work on the instability of eccentric Tainter gates. She undertook the study of the Folsom Dam gate failure as her thesis topic under my direction when she enrolled as a graduate student. She successfully applied theoretical techniques to identify the essential flow-induced coupled-mode dynamic instability that any non-eccentric Tainter gate possesses. She was awarded her Ph.D. degree in 2002 from Osaka Electro-Communication University.

I am very pleased to note that two International Symposia related to Tainter gate vibrations were held at Osaka Electro-Communication University. The first Symposium was the Commemorative International Symposium for the 40th Anniversary of the Foundation of the Osaka Electro-Communication University, which was held November 4 to 5, 2001. The topic of the symposium was Flow Induced Vibration of Engineering Structures: Lessons from Recent Tainter Gate Failures. Invited speakers from overseas were Professor Eduard Naudascher of University of Karlsruhe, Professor David Weaver of McMaster University, Professor Charles W. Knisely of Bucknell University and Senior Researcher Robert Todd from the United States Bureau of Reclamation (Denver). Domestic invited speakers were Professor Fumio Hara of Tokyo Science University, Professor Masaru Matsumoto of Kyoto University and Professor Shigehiko Kaneko of Tokyo University. A commemorative closing address was presented by Professor Naudascher, included as an appendix to this final chapter. Figure 10 is a photograph of Professor Naudascher at our 2001 Symposium.

The second International Symposium with the theme Impending Plans for Assuring the Dynamic Stability of U.S. Tainter Gates was held on March 27, 2006. Invited speakers were Dr. Robert Todd of the USBR, Supervising Engineer Mark Schultz from the Department of Water Resources, State of California, Manager Dr. Stephen Slinkard of United States Army of Corps of Engineers, and Professor Charles W. Knisely of Bucknell University. The domestic invited speakers were Professor Emeritus Hiroji Nakagawa of Kyoto University, Professor Shigehiko Kaneko of Tokyo University, Professor Tetsuya Sumi of Kyoto University, Manager Koki Kataoka of Kansai Electric Power Company, Professor Toru Iijima of Muroran Institute of Technology and Professor Yoshinobu Tsujimoto of Osaka University. A commemorative photograph from this second International Symposium is shown in Figure 11.

Our research work over the past 45 years are presented in this book. The most significant feature of this book is the successful development of an entirely theoretical method to predict the flow-induced vibration problems of hydraulic structures. A second very important development is the bold simplified modeling of the flow fields and vibration systems, which made possible the theoretical development. Small errors between the theory and measurement could be accounted for by small systemic empirical coefficients that modified the predictions for better agreement with model and field experiments.

The delay in the completion of this manuscript resulted from my extremely slow work pace as I faced my impending retirement. I was encouraged by my colleague, Professor Knisely, who was always very gentle and very patient with me. I trust him deeply from the bottom of my heart. The publication of this book would have never been realized without a great effort by Professor Knisely and the continuing kind support by his wife Karin Knisely, to both of whom I would like to express my sincere gratitude.  My sincere apology for the delay in the preparation is extended to the IGI Global publishing company people, represented by Jan Travers, Keith Greenberg and others.

We sincerely hope that this book is effective in preventing further human-made disasters such as Wachi and Folsom Dam gate failures.

Professor Emeritus Noriaki Ishii, OECU, August 31, 2016

CLOSING

This book documents a combined investment of over 100 person-years of effort. For each of the authors, this effort has been both a challenge and a pleasure. It has been immensely rewarding to have this opportunity to reflect on developments over a career and to try to formulate a logical explanation of what transpired.