Resonance Behavior of a Liquid Bridge Caused by Horizontal Vibrations

Abstract

This paper describes the resonance behavior of a liquid bridge subjected to horizontal vibrations of small ampli- tudes to investigate the g-jitter effect on material processing in space using the FZ method. A model is proposed to es- timate resonance frequencies of a liquid bridge based on a mass-spring-damper system. Experiments have also been carried out to confirm the existence of resonance frequencies and applicability of the proposed model. Several liquid bridges with different test liquids and sizes were formed between two disks. The test section was set on a vibration stage that could apply sinusoidal translation horizontally, and the liquid bridge behavior was observed using a CCD camera. Experiments were carried out by applying horizontal vibrations at a constant acceleration level at various fre- quencies 0.1-20 (Hz). The surface oscillation amplitude remained low at all frequencies tested except for a certain fre- quency, at which significantly larger amplitude was obtained due to the resonance behavior of the liquid bridge. The measured resonance frequency compared well with the theoretical prediction. The model was also used to predict the resonance frequencies of cylindrical liquid bridges obtained in space experiments during the Space Lab D-1 mission. Good agreement between the model predictions and the space experiment results obtained suggests that the present model is also capable of predicting the resonance frequencies of cylindrical liquid bridges in space. The effects of deformation of the equilibrium shape and existence of a small bubble trapped inside the liquid bridge on the resonance frequency are also discussed.