On the leak-induced transient wave reflection and dominance analysis in water pipelines

The leak-induced reflection information forms the basis of developing and applying transient-based leak detection methods in water-filled pipelines. The transient reflection method (TRM) has been widely incorporated in various leakage problems, and affecting parameters in the process are closely investigated in specific cases. However, the TRM literature lacks a global assessment of the relative importance of each parameter for a general inference on the contribution of each independent variable to the desired reflection criterion, which assists in leakage management. Besides, in the majority of previous studies, the leak-induced reflection wave at the measurement point is approximated by that at the leaky point, i.e., the propagation behavior and process of the reflected wave from the potential leak location to measurement point is ignored, leading to inaccuracy in sizing potential leaks by the TRM. To resolve these issues, this study firstly derives the leak-induced reflection coefficient at the measurement point by incorporating the additional damping effect of the reflection wave propagation process along the pipeline, which is then fully validated by MOC-based numerical and experimental laboratory applications. To further understand the contribution of different factors in the derived reflection coefficient, a systematic analysis is conducted based on dimensional analysis and extensive numerical simulations. The obtained results are characterized by the dominance analysis so as to explore the importance ranking of different dimensionless factors to the leak-induced reflection coefficient in the pipeline system. The analysis results indicate that, amongst all the dimensionless parameters, the leak factor provides the largest influence and contribution to the wave reflection coefficient (with about 40% contribution), followed by the transient intensity (23%) and initial system and flow conditions (20%), and lastly the measurement distance from leak location (17%). The finding of this study is helpful in leakage management as it aims to understand and explain the applicability and effectiveness of the TRM under different conditions.