Resistência ao escoamento uniforme em canais circulares lisos.

Abstract

A great number of hydraulic models can be applied to represent the uniform turbulent flow in channels. The equation of Manning, one of the more used by designers, can cause a 30% error in the results, according to the manual in the 9 of WPCF (1972). Like this, as the equation of Manning, several other methodologies don't represent the effect in the way of the traverse section of the flow satisfactorily. In this work, it was made a bibliographical survey on the importance of this effect, as well as a study of the application of two methodologies that search to compute the form effect satisfactorily. The model developed by Silva (1992), based on the basic equations of the uniform flow and considering a distribution non uniform of the tension of shear in the wet perimeter, it was applied in channels of circular section, and, in spite of having based purely in a procedure analytic, it presented results of great importance, because the form parameters used by Silva (1992), came with behavior similar to the used by Kazemipour and Apelt (1980). The methodology developed by Kazemipour and Apelt (1980), starting from considerations of the dimensional analysis, it was adjusted in way to become completely equacionável without the need of graphic resources. The method of Kazemipour was shown quite efficient for the calculation of free uniform flow in flat channels of circular geometry. The geometric parameters (P, D, yD) used by these researchers they were shown enough to represent the form of the geometry of the traverse section in the calculation procedures. A comparison between these these models through the analysis of the form parameters used to represent the geometry of the section proven the likeness of the form parameters used in the two methodologies. Finally is presented a calculation procedure using the "method of Kazemipour" adjusted analytically.