Parametric depth ratio study on tuned liquid dampers: Fluid modelling and experimental work

Tuned liquid dampers (TLDs) utilize sloshing fluid to absorb and dissipate structural vibrational energy. A prerequisite to TLD design is establishing a suitable model to describe the fluid response. Numerous fluid models have been presented in literature; each utilizes simplifying assumptions which make the model valid under certain flow conditions. TLDs are often designed with fluid depth to tank length ratios less than 25%. At these depths, response characteristics change relatively rapidly with decreasing fluid depth, making it unlikely that one model is suitable over the entire range. The goal of this study is to determine when certain fluid models can be used.Three fluid models are considered: shallow water wave theory, a small depth multimodal model, and an intermediate depth multimodal model. The models are briefly presented and their basic assumptions are identified. A parametric shake table testing program is conducted which varies the fluid depth of a rectangular tank equipped with damping screens. Experimental time history and frequency response plots are created for comparison with each fluid model at several fluid depth ratios and excitation amplitudes. The range of validity for each model is described in terms of the fluid depth ratio, and the Ursell parameter. The results of this study will help TLD designers determine a suitable fluid model for dynamic analysis of a structure-TLD system.