Bachir Achour

Ressaut contrôléar seuil dans un canal profilé en U

The control of a hydraulic jump by both thin-crested and broad-crested sills in a U-shaped channel is examined theoretically and experimentally. Under certain simplifications, the theoretical development results in explicit relations for the relative sill height, by including the effect of approach velocity. This also leads to a similar condition for the control by a sill in the rectangular channel, by extension of the Forster and Skrinde approach. A particular study is presented to define the conditions required for the minimum height of a broad-crested sill. Finally, the relative length of jump is quantified by accounting for the relative depth of the approaching flow.

Jump flowmeter in a channel of triangular cross-section without weir

The devices employed for the measurement of discharges in free surface channels usually generate a great headloss, incompatible with irrigation purposes in flat areas. To solve this problem, the author presents a new type of flowmeter which combines the advantages of the triangular weir and those of the Parshall weir.

Effect of sill in the hydraulic jump in a triangular channel/ Effet du seuil sur le ressaut hydraulique dans un canal triangulaire

Hydraulic jumps are experimentally examined in a horizontal symmetrical triangular channel of 90° central angle. This study investigates the main features of both the minimum-B jump and the sill-controlled jump under various inflow conditions. The development of jumps was ensured using either a thin-crested or a broad-crested sill. Based on a large experimental program, the data were fitted to empirical relations to detect the effect of the inflow Froude number on the relative sill height, the sequent depths ratio and the non-dimensional toe position of the sill. The relations obtained are recommended for designing irrigation ditches.

Control of hydraulic jump by sill in triangular channel

The control of an hydraulic jump by a thin wall continuous sill in a triangular channel with an aperture of 90° is analyzed experimentally. A relationship for the control of the hydraulic jump under any conditions of generation is presented in an adimensionnal form in order to have a general validity character. The sill effect on the stilling basin is observed and evaluated. This research has its application in the ditch irrigation with triangular shape, using the jump ability to raise the flow head plane downstream.

The Mzab foggara: an original technique for collecting the water rising

Abstract This paper describes for the first time an original foggara, different from the classical foggara (foggara of Gourara) which collects water from the Intercalary Continental aquifer. Located in the middle of the Mzab River, this hydraulic system called the Mzab foggara is intended to exploit the flood waters. Two missions were carried in 2009 and 2010 in the Mzab Valley to describe the hydraulic system. The Mzab foggara constitutes of a gallery of ovoid form 200 m long equipped with 9 air shafts and a 900 m long seguia. The foggara of the Mzab River can drain water flow of 5 m3·s-1 to irrigate western part of the palm plantation of Ghardaia (located 600 km south of Algiers). W artykule opisano po raz pierwszy oryginalną foggarę (podziemna instalacja wodna, używana do zaopatrywania siedzib ludzkich w wodę oraz nawadniania pól uprawnych na terenach suchych i pustynnych; inne nazwy to kanat i kariz - na podstawie Wikipedii), odmienną od klasycznej foggary z Gourara, która gromadzi wodę z kontynentalnego inkluzyjnego poziomu wodonośnego. Ten system hydrauliczny, zwany foggarą Mzab, usytuowany jest w środkowym biegu rzeki Mzab i przeznaczony do eksploatacji wód powodziowych. W celu opisania systemu przeprowadzono dwie wyprawy do doliny rzeki Mzab w latach 2009 i 2010. Foggara Mzab składa się z owalnej galerii długości 200 m, wyposażonej w 9 szybów wentylacyjnych i w 900-metrowy kanał rozdzielczy. Foggara rzeki Mzab może dostarczać wodę w ilości do 5 m3·s-1 do nawadniania zachodniej części plantacji palm w Ghardaia (600 km na południe od Algieru).

Hydraulic jump in a sloped triangular channel

The hydraulic jump in a sloped triangular channel of 908 central angle is theoretically and experimentally exam- ined. The study aims to determine the effect of the channels slope on the sequent depth ratio of the jump. A theoretical relation is proposed for the inflow Froude number as function of the sequent depth ratio and the channel slope. An experi- mental analysis is also proposed to find a better formulation of the obtained relation. For this motive, six positive slopes are tested. The relations obtained are recommended for designing irrigation ditches.

The qanat of Algerian Sahara: an evolutionary hydraulic system

Abstract This article discusses for the first time a study on the connection and interconnection of qanats located in the Algerian Sahara. During the missions in the oases of Touat and Gourara in 2009, 2010 and 2011, we have been impressed by the complexity of the network of water distribution. The seguias of differents sections take all the senses. Connections are made between qanats to ensure water supply to each owner. In this study, we identified nine models for connecting qanats.

Design of a Pressurized Rectangular-Shaped Conduit Using the Rough Model Method (Part 1)

The rough model method is successfully used to design a pressurized rectangular shaped conduit characterized by two linear dimensions. In this study, the focus is on the calculation of the horizontal linear dimension of the conduit. In a first step, the method is applied to a referential rough model in order to establish the relationships that govern its hydraulic characteristics. The obtained equations are of the third degree and are easily solved by trigonometric and hyperbolic functions. In a second step, these equations are used to easily deduce the linear dimension sought by introducing a non-dimensional correction factor. Practical example is taken to enable the hydraulic engineer to better understanding the advocated method and to observe the facility with which design of such a geometric profile can be performed. The calculation uses a strict minimum of data measurable in practice, in particular the absolute roughness.

Hydraulic jump in a suddenly widened circular tunnel

The evolution of a hydraulic jump in a suddenly widened circular cross-section is investigated theoretically and experimentally. The flow upstream is not developed. A functional relationship is defined linking the various parameters which influence the phenomenon. The analysis makes it possible to compute the extent of the widening of the tunnel which is necessary to ensure development of the jump. The characteristics of the jump such as its length and axial surface profile are quantified.

Chezy’s resistance coefficient in an egg-shaped conduit

Abstract When calculating uniform flows in open conduits and channels, Chezy’s resistance coefficient is not a problem data and its value is arbitrarily chosen. Such major disadvantage is met in all the geometric profiles of conduits and channels. Knowing the value of this coefficient is essential to both the design of the channel and normal depth calculation. The main objective of our research work is to focus upon the identification of the resistance coefficient relationship. On the basis of the rough model method (RMM) for the calculation of conduits and channels, a general explicit relation of the resistance coefficient in turbulent flow is established with different geometric profiles, particularly the egg-shaped conduit. Chezy’s resistance coefficient depends strongly on the filling rate, the discharge, the longitudinal slope, the absolute roughness of the internal walls of the conduit and the kinematic viscosity of the liquid. Moreover, in this work, a simplified method is presented to determine Chezy’s resistance coefficient with a limited number of data, namely the discharge, the slope of the conduit, the absolute roughness and the kinematic viscosity. Last but not least, after studying the variation of Chezy’s resistance coefficient as a function of the filling rate, an equally explicit expression is given for the easy calculation of this coefficient when its maximum value is reached. Examples of calculation are suggested in order to show how the Chezy’s coefficient can be calculated in the egg-shaped conduit.