Abstract—Experimental modal analysis, using an impact hammer and accelerometers, was conducted on a full-scale flap gate with a height of 0.963 m and a span of 14.8 m to determine its in-air natural frequencies, mode shapes, and modal damping. Subsequently, the in-water self-excited vibration characteristics of the gate (without any spoilers) were recorded using the same accelerometers. The major in-air vibration characteristics (the mode shape, frequency and damping ratio for the damped vibrations), as well as the major in-water self-excited vibration characteristics (the excitation ratio and frequency of the self-excited vibrations in-water) are tabulated. In parallel with these experiments, calculations of the inherent in-water vibration frequency of the gate using a potential flow theory, based on input from the in-air modal testing, are presented. Comparison of the calculated inherent in-water vibration frequency with the measured frequency of the in-water self-excited vibration confirms the validity of the present theoretical analysis.

Index Terms—Flap gate, Flow-induced vibration, Added mass, Modal analysis, Self-excited vibration, In-water frequency

Cite: Keiko Anami, Noriaki Ishii, Charles W Knisely, and Yukio Matsumoto, "Field Test Validation of Analytical Model for Vibration Characteristics of a Flap Gate Undergoing Self-Excited Vibration," International Journal of Mechanical Engineering and Robotics Research, Vol.3, No. 4, pp. 1-15, October 2014.