Vibration and damping analysis of flexible aluminum tube under the variation of support plate geometry using low speed water tunnel

摘要

Vibration response and damping effects on flexible aluminum tube placed in tube-bundle under fluid interaction velocity of 0.5 m/s using water tunnel, is analyzed experimentally for drag and lift direction. The study is undertaken to reduce the flow-induced instabilities in heat-exchanger, proposing low-vibrating design approach. Therefore, three tube bundles in triangular arrangement using distinct support plate thickness of 2 mm, 2.8 mm, and 3.6 mm under (P/D) ratio of 1.45 are developed, respectively. The vibrations are sensed through trTaxial accelerometer mounted at top of central-tube. The damping factors are assessed for monitored/central tube of each tube-bundle at tuned natural frequencies of 9, 8, 7, and 6 Hz, respectively. Whereas, tube-vibration response is further analyzed in terms of RMS-acceleration and dimensionless magnitude at fixed natural frequency of 8 Hz. The results highlight that, the damping factors (under all four natural frequencies) exhibit increasing and the tube-vibrations show decreasing trend with increase in support plate thickness, respectively. Moreover, successive decrease in natural frequency of tube (9-6 Hz) influence the damping factors to increase for each tube bundle. Based on assessment, it is noted that tube-bundle comprising 3.6 mm thick support plate along 8 Hz natural frequency, shows maximum stability for given setup.