Hydraulic instrumentation and its application to the Nikuradse and Prandtl Von-Kárman equations for the estimation of composite roughness in diversion tunnels Case study: Grijalva River

Abstract

In the recent hydroelectric power plants built in Mexico (P.H. El Cajón, P.H. La Yesca and Grijalva River tunnels), the diversion tunnels have been designed with a combination of materials: hydraulic concrete in its template and concrete cast in its walls and vault, which allows to reduce hydraulic losses and get a greater discharge capacity to guarantee the hydrological safety of the dam during the build time, in addition to achieving considerable cost savings. In order to monitor this capacity, several instrumentation projects have been carried out, recording the hydraulic variables in different sections, in addition to estimating the representative parameter of the composite roughness. This article relates how estimates the composite roughness parameter in diversion tunnels, in a case study: “Communication tunnels of the Grijalva River”, upstream of the Penitas Hydroelectric Power Plant, using hydraulic instrumentation to measure, among other variables, the speed in the area near to the wall. And applying the boundary layer theories of Nikuradse and Prandtl-Von Kárman to determine the equivalent roughness in the walls, as well as the review of 17 empirical equations to finally obtain the representative composite roughness of the tunnels.