Avaliação experimental dos transientes hidráulicos em condutos forçados sob infestação pelo mexilhão dourado (Limnoperna fortunei)

Abstract

Operational maneuvers in pressurized hydraulic systems, such as rapid valve closure, may cause hydraulic transients characterized by abrupt variations in pressure and flow velocity, which can compromise the structural integrity of pipelines. In parallel, biological colonization by Limnoperna fortunei (golden mussel) has caused significant changes in flow conditions in Brazilian hydraulic systems, especially in hydroelectric power plants, pumping stations, and water supply networks, since the late 1990s. Biofouling increases internal roughness and reduces the effective cross-sectional area of pipelines, potentially intensifying pressure surge effects. The objective of this study is to experimentally demonstrate that penstocks infested by the golden mussel exhibit higher overpressure levels than clean pipes when subjected to the same flow rate and valve closure time. The methodology consisted of developing an experimental test rig composed of an upstream reservoir, a flow meter, three pressure transducers distributed along the pipe, and a pneumatically actuated fast-closing valve. Biofouling was simulated using 3D printing based on the scanning of colonized surfaces, allowing reproduction of the geometry of incrustations in nominal diameters of 2½", 3", and 4". Rapid valve closure tests were performed in control and biofouled pipes under different operating flow rates, with maximum pressure values recorded. The results showed that, for the same initial flow rates and the same block valve closure time, biofouled pipes presented significantly higher pressure peaks than clean pipes. It was found that an increase in the valve closure time was required to maintain overpressure levels within admissible design limits. It is therefore concluded that golden mussel colonization substantially alters the transient response of hydraulic systems, making it essential to reassess operational parameters and valve closure laws in infested pipelines in order to ensure operational safety and energy efficiency.