EVALUACIÓN Y APLICACIÓN DE LA TÉCNICA DE LSPIV PARA ESTIMAR LA VELOCIDAD SUPERFICIAL EN OBRAS HIDRÁULICAS

Abstract

Particle Image Velocimetry (PIV) is a non-intrusive optic measuring technique which obtains, in an indirect way through image processing, the bi-dimensional speed flow based on the speed measure of the particles or different elements known as flow tracers. These tracers can be solid particles, bubbles or patterns driven by fluids turbulence. PIV technique has been used traditionally in labs with highly controlled experiments. However, the application has been performed in the field through several years with the name of LSPIV and it has helped acquiring speed references on river surfaces and physical model scales inside laboratories. This project is dedicated to the design and operation of a LSPIV system assembled as a means to evaluate the technique and also to propose alternatives and new tracers. Moreover, it has been proposed to try to solve several obstacles that investigators have found out in the context shown. The LSPIV system has been implemented to determine the superficial speed flows and use on hydraulic channels and models using components such as flow visualization (tracers), lighting, recording, orthorectification and image processing. For the sowing of the lands, several kinds of tracers and techniques were used. Consequently, the most efficient ones were the paper confetti and biobolas ones. The lighting was set to be daylight in the outdoors and halogen lighting inside the laboratories. A semi-professional video camera was used for the image capturing, while the orthorectification and image processing were performed with MAT_LSPIV (such program was performed in Matlab by Iowa’s “IIHR” which has a graphic interface to simplify its use). Speed measures were obtained using a standard cross-correlation. Once in use, the superficial speed was successfully measured in a channel located in Santa Isabel ecological park, Morelos. In addition, some other superficial speeds were measured in an IMTALAB laboratory model using four different tracers and artificial light produced by halogen lamps. The significant results of this project open up new ways of research in the field to acquire valuable speed data in rivers. As a result, this will help us know expenses and some situations where the installation of measurement equipment won’t be possible.