1D-Permeability Measurements Based on Ultrasound and Linear Direct Current Resistance Monitoring Techniques

摘要

Knowledge of the flow front position of the injected fluid is essential for Liquid Composite Moulding (LCM) process development and optimisation. This paper presents two sensing techniques, Linear Direct Current (LDC) and ultrasound interface change, that deliver different types of information on the flow front position (continuous and punctual). Preliminary flow measurements were conducted to quantify the sensitivity of the considered monitoring techniques and to optimise the experimental set-up. Evaluation criteria include qualitative comparison of results delivered by visual, LDC and ultrasound monitoring systems with regard to position and shape of the flow front. The maximum deviations between visual and the investigated monitoring systems are DELTA x_(LDC)=33.9X10~(-3) m and respectively DELTA x_(US)=2.8X10~(-3) m. the second part of the paper presents permeability characterisation in the 1D-flow channel based on flow front position delivered by LDC, ultrasound monitoring techniques and visual recording. The flow front position determined by conventional methods based on video capture is taken as reference. Comparison of the permeability values (K_(visual), K_(LDC) and K_(US)) shows a maximum deviation of 6.93 percent given by the LDC-system. The ultrasound interface change measurement principle allows very accurate and reproducible punctual flow front tracking and shows a maximum deviation compared to the reference permeability (K_(visual)) of 3.32 percent. This study shows the potential of the investigated techniques for flow front monitoring of LCM injection processes.