Flexible concrete protective coating resistance to approach flow exposure

Abstract

In order to protect the bottom and coastal slopes of natural channels and artificial reservoirs from channel deformations, various shore reinforcing structures are often used. One of this structures is the universal flexible protective concrete coating. When using this kind of structures, it is necessary to take into account their interaction with the approach flow. At the flexible protective coatings operating, one of the problems is the “wrapping” of the coating body. To calculate the stability assessment of the surface coating, it is necessary to know the value of the coefficient of hydrodynamic resistance of the protective coatings. It is determined mainly by its shape. Currently, various forms of surface coatings from various materials are used. In most cases, the resistance of such structures is assumed approximately, based on the known values of the resistance coefficients of bodies of various shapes. As a rule, the elements of protective coatings have a specific form, the resistance of which must be established experimentally. The article presents the results of an experimental determination of the hydrodynamic drag coefficient of a universal flexible concrete protective coating (a universal flexible protective mat) on aerodynamic and hydraulic experimental stands. Used laboratory equipment with basic operating characteristics, examples of experimental models, and basic operating conditions during experiments are described. It is shown that the value of the coefficient of hydrodynamic resistance decreases with increasing Reynolds number. The obtained values of the hydrodynamic resistance coefficient in some cases exceed the values recommended for calculating the maximum permissible flow velocity when assessing the stability of a protective coating. It is concluded that it is necessary to experimentally evaluate the hydrodynamic resistance coefficient for each model of protective coatings. The recommended value of the hydrodynamic resistance coefficient for the studied modification of a flexible protective concrete coating is established.