The transmission of pump induced pressure disturbances to nano-precision instrumentation

Abstract

High-tech systems are subjected to strict temperature requirements. Therefore temperature control using cooling water is vital for thermal stability. Unfortunately, components like pumps and fluid couplings generate flow disturbances, resulting in mechanical vibrations that influence the performance of the system. This research focusses on the propagation of pump induced pressure oscillations to nano-precision instrumentation. A generic vibration isolated precision system has been considered. The system contains a cooling conduit, which is connected to a mechanically isolated pump by viscoelastic tubing. Pressure disturbances are transmitted to the system due to fluid-structure interaction at curved tubes in the cooling conduit. Luckily, viscoelastic tubes are proven to attenuate pressure oscillations. A model has been presented to predict the system disturbance due to pressure oscillations produced by a pump. An experimental setup has been considered to validate the model. The setup represents a simple mechatronic system. Results show that the model provides a decent qualitative description of the spectral disturbance behaviour, however it is only capable of giving an order of magnitude estimation of the overall disturbance. Based on the knowledge gained in this research, possible design improvements can be proposed. These include changing the dimensions of the viscoelastic tubes and altering the mechanical eigenfrequencies of the cooling conduit.