Speaker
Description
CEPC mechanical-stability studies specify stringent ground-motion requirements, with RMS displacement integrated over 1-100 Hz of ≤4 nm for the machine-detector interface (MDI) and ≤24 nm for the collider arc, straight and RF sections. In addition to ground-borne vibration, cooling-water systems can act as a direct source of mechanical excitation in accelerator magnet systems. Previous in situ cooling-water on/off measurements on the installed HEPS QD2 quadrupole magnet showed measurable changes in magnet vibration, motivating further investigation of the underlying fluid excitation and structural response.The present work investigates the unsteady fluid excitation generated by cooling-water flow and its relationship with structural vibration under controlled conditions. Large-eddy simulation is used to resolve transient wall-pressure fluctuations and provide distributed pressure loading for one-way fluid–structure interaction analysis. The study also incorporates controlled-flow vibration measurements on simplified piping specimens under matched flow conditions to evaluate the predicted structural response. Preliminary numerical results for the current piping model show pronounced spatial variation of pressure fluctuations, highlighting the importance of retaining the distributed nature of the pressure loading in structural-response analysis.The combined numerical and experimental study provides a basis for extending the analysis to realistic accelerator magnet cooling systems, with the ultimate goal of quantitatively predicting cooling-water-induced vibration.
