Hydraulic resistances of derivation channels of hydropower facilities

Bakhtiyor Uralov,Alisher Allanazarov,Khumoyun Kholmatov,Sanatjon Khidirov,Farokhiddin Uljaev,Ikboloy Raimova,E Vdovin

doi:10.1051/e3sconf/202127403010

Abstract

Currently, many authors have studied the uniform axisymmetric pressure head laminar and turbulent movement of water in hydraulic smooth and rough (with uniform roughness) pipes of circular cross-section. The results obtained in the study of a plane-parallel turbulent flow in pressure channels allow here only to outline the structure of the corresponding dependencies and to clarify the simplest case of unpressurized fluid movement, when this movement can also be reduced to plane-parallel or, in other words, to movement in channel of infinitely large width with a flat bottom. In all other cases, the only way to solve the problem is experiment. But the possibilities of the experiment are limited, as are limited, and in a number of cases debatable, and the information accumulated to date on the uniform free-flow motion of fluid in channels of various cross-sectional shapes. The unpressurized uniform movement of fluid in channels of various cross-sectional shapes has been completely insufficiently studied. The construction of numerous free-flow watercourses, as well as machine channels of pumping stations, requires scientifically based calculation methods. For the correct establishment of hydraulic calculation methods, a sufficiently deep study of the physical essence of the phenomena occurring in the free-flow derivation channels is necessary. The extensive construction of numerous free-flow watercourses, as well as hydroelectric power plant (HPP) derivation channels, requires scientifically based calculation methods. For the correct establishment of hydraulic calculation methods, a sufficiently deep study of the physical essence of the hydraulic phenomena occurring in the free-flow derivation channels of HPPs is necessary.

Highlights

The question of head losses with uniform steady motion in cylindrical channels - head losses along the length - has more than a century of history
As shown by the preliminary analysis, this group for the case of free-flow movement includes, in particular, rectangular, trapezoidal, parabolic, semicircular, which are often found in the practice of hydraulic engineering and hydropower construction, including the derivation channels of hydroelectric power plants
2 Methods The method for studying this work is the analysis of the operation of the hydroelectric power plant (HPP) derivation channels in various modes, operating in different hydraulic conditions and different values h – flow depth, Ṛ - hydraulic radius and χ – of the wetted perimeter of the living section of the flow, taking into account the influence of the roughness and shape of the channel on the hydraulic resistance of the derivation channels of the hydroelectric power station

Summary

Introduction

The question of head losses with uniform steady motion in cylindrical channels - head losses along the length - has more than a century of history. It was believed that in free-flow derivation channels with a «correct» cross-sectional shape, its influence on the value of pressure losses can always be estimated with an acceptable approximation using the hydraulic radius.

Methods

Results and discussion

Conclusions