Experimental Study on Structural Vibration Characteristics of Single Rod in Different Flow States of Water

In the nuclear reactor, flowing state of surrounding fluid will change structural vibration characteristics of fuel rods, which may lead to severe resonance and damage of fuel rods. Therefore, it is necessary to study structural vibration characteristics of fuel rods in different fluid flow states. In this paper, based on experiment, structural vibration characteristics of a single rod in different water flow states and different restraint modes are obtained by hammering method. The results show that different restraint modes have influence on dry mode, wet mode and structural vibration characteristics of the rod. Under condition of no excitation, when flow rate is lower than 1m/s, the response frequency and flow velocity change trend is the same under different restraint modes, response frequency of test rod with increases of flow rate. When flow rate is more than 1m/s, the response frequency varies with flow rate in different restraint modes. Under the fixed support, the excitation ways and excitation positions have no effect on natural frequency of rod. For simply supported, the excitation positions have great influence on the natural frequency of rod. It has reference significance for the safety design of fuel rods.