Based on our unsteady numerical simulations flow in subchannels, a new correlation of the peak frequency in terms of the Strouhal number and non-dimensional gap size was proposed. By substituting the proposed correlation for the existing theoretical correlation of the gap Stanton number, the gap Stanton numbers of high Prandtl number and low Prandtl number fluids were predicted more accurately than the same theoretical correlation with substituting other empirical correlations of the Strouhal number. Furthermore, the molecular diffusion term in the theoretical correlation of the gap Stanton number was improved by considering the flow pulsation. The improved correlation shows much more accurate predictability of the gap Stanton number of typical liquid metal than the original one.
The fluid temperature may fluctuate in a mixing-tee-junction and thereby thermal fatigue may occur and a frequency response model can predict this. This study aims to propose a weight function for two-dimensions, which is a part of this frequency response model, to translate the temperature fluctuation to a stress-intensity-factor. In addition, the function shall be compared against OECDs FAT3D experiments.
(37) Experimental Analysis for Separation Vortices Behavior by Pressure Fluctuation Measurement in Elbow Flows Using 1/7-Scale Cold-Leg Experimental Facility
Simulation of noise spectrum from the cavitation bubble have been calculated. The simulation assumed a bubble with radius of 10 in the change of liquid static pressure. The equation used to simulate the bubble radial motion is the Keller-Miksis equation. The spectrum was generated from the pressure pulse results from 10-12 s to 0.01 s and sampling frequency of 2 MHz. The result shows that cavitation bubble produced noise at higher frequency region. The noise is relatively flat up to 10 kHz. From 10 kHz to 20 kHz the noise starts to increase gradually.