Recent developments in unsteady pipe flow experimentation at the University of Montenegro
This paper presents recent experimental results of pressure measurements during filling and emptying of a relatively small-scale pipeline at the University of Montenegro. Experimental setup for investigation of water hammer and its special effects (unsteady friction, cavitation, column separation, trapped air, fluid-structure interaction - FSI), and pipeline filling and emptying is installed at the Faculty of Mechanical Engineering. It consists of an upstream end high-pressurized tank, horizontal steel pipeline (total length: 55.37 m, inner diameter: 18mm, pipe wall thickness: 2 mm), four valve units positioned along the pipeline including the end points, and a downstream end outflow tank. The setup was upgraded in 2018 with the installation of new piezoresistive pressure transducers and pipe displacement sensors as well as additional electro-pneumatically operated ball valve at the upstream end of the pipeline. The filling of an initially empty pipeline is performed by a sudden opening of the valve positioned at the highpressurized tank filled with water. The pipeline emptying process is accomplished by highpressurized air supplied from the air reservoir installed in the air supply line. The highpressurized tank is closed, and the downstream end valve is opened. Experimental runs have been performed with different initial values of pressure in the upstream end high pressurized tank (filling) and air supply line (emptying). Results of new pressure measurements are analyzed and commented, with a reference to the previous experiments presented at 6th IAHR WG Meeting in Ljubljana, 2015.