The field-scale experimental facility at Beacon Hill, Kowloon, HK, comprises a 250 m long pipeline network of 150 mm diameter (NS180) HDPE pipe. An upstream pressure-reducing valve (PRV) regulates incoming system pressure from 0.5 to 6 bar. The system has 8 access points allowing deployment of intrusive instruments (e.g., high frequency hydrophones and/or miniature robots). Valved cross-connections permit single, branched, or looped network topologies. The system has 12 bends ranging from 60 to 180 degrees, and the maximum allowable flow is at Reynolds number of 1.5×10^(5) and Mach number of 2.5×10^(-3). The facility is adaptable to provide a controlled testing environment to validate time-reversal theories.
Fig. 1: Schematic of the pipe system and example of high frequency (HF) access point for HF-TR experiments.
Technical specifications and measurement capabilities:
The water supply is fed from the Beacon Hill reservoir at around 61 m of head;
The flow is monitored by an electromagnetic flow meter, and the upstream pressure can be set with a pressure reducing valve (PRV). A ball valve designed for rapid closure is installed at the downstream end of the system.
Acceleration and displacement sensors can be easily mounted. Triaxial piezoelectric accelerometers with high sensitivities of 10 mV/g (IPC 352A60 PCB accelerometer) and 316 pC/ms–2 (B&K 4326-A, charge accelerometer) with frequency ranging up to 60 kHz can be used. Displacements are captured with electrical resistive strain gauges.