Modeling and Controlling Flow Transient in Pipeline Systems: Applied for Reservoir and Pump Systems Combined with Simple Surge Tank

When transient conditions (water hammer) exist, the life expectancy of the system can be adversely impacted, resulting in pump and valve failures and catastrophic pipe rupture. Hence, transient control has become an essential requirement for ensuring safe operation of water pipeline systems. To protect the pipeline systems from transient effects, an accurate analysis and suitable protection devices should be used. This paper presents the problem of modeling and simulation of transient phenomena in hydraulic systems based on the characteristics method. Also, it provides the influence of using the protection devices to control the adverse effects due to excessive and low pressure occuring in the transient. We applied this model for two main pipeline systems: Valve and pump combined with a simple surge tank connected to reservoir. The results obtained by using this model indicate that the model is an efficient tool for water hammer analysis. Moreover, using a simple surge tank reduces the unfavorable effects of transients by reducing pressure fluctuations

Hybrid Particle Swarm and Neural Network Approach for Streamflow Forecasting

In this paper, an artificial neural network (ANN) based on hybrid algorithm combining particle swarm optimization (PSO) with back-propagation (BP) is proposed to forecast the daily streamflows in a catchment located in a semi-arid region in Morocco. The PSO algorithm has a rapid convergence during the initial stages of a global search, while the BP algorithm can achieve faster convergent speed around the global optimum. By combining the PSO with the BP, the hybrid algorithm referred to as BP-PSO algorithm is presented in this paper. To evaluate the performance of the hybrid algorithm, BP neural network is also involved for a comparison purposes. The results show that the neural network model evolved by PSO-BP algorithm has a good predictions and better convergence performance

Roe Scheme for Two-layer Shallow Water Equations: Application to the Strait of Gibraltar

The flow trough the Strait of Gibraltar could be analyzed as a problem of two-layer hydraulic exchange between the Atlantic ocean and the Mediterranean sea. The shallow water equations in both layers coupled together are an important tool to simulate this phenomenon. In this paper we perform an upwind schemes for hyperbolic equations based on the Roe approximate Riemann solver, to study the resulting model. The main goal assigned was to predict the location of the interface between the two layers. Therefore the computational results obtained are compared to previous results and experiments

RBF Based Meshless Method for Large Scale Shallow Water Simulations: Experimental Validation

2D shallow water equations with depth-averaged k−ε model is considered. A meshless method based on multiquadric radial basis functions is described. This methods is based on the collocation formulation and does not require the generation of a grid and any integral evaluation. The application of this method to a flow in horizontal channel, taken as an experimental device, is presented. The results of computations are compared with experimental data and are found to be satisfactor

Water Network Rehabilitation with a Structured Messy Genetic Algorithm

The importance of water distribution network rehabilitation, replacement and expansion is discussed. The problem of choosing the best possible set of network improvements to make with a limited budget is presented as a large optimisation problem to which conventional optimisation techniques are poorly suited. A multi-objective approach is described, using capital cost and benefit as dual objectives, enabling a range of non-inferior solutions of varying cost to be derived. A Structured Messy Genetic Algorithm is developed, incorporating some of the principles of the Messy Genetic Algorithm, such as strings which increase in length during the evolution of designs. The algorithm is shown to be an effective tool for the current optimisation problem, being particularly suited both to the multi-objective approach and to problems which involve the selection of small sets of variables from large numbers of possibilities. Two examples are included which demonstrate the features of the method an..

Computing two dimensional flood wave propagation using unstructured finite volume method: Application to the Ourika valley

International audienceThis study is devoted to the flood wave propagation modelling corresponding to a realistic situation. The equations that governs the propagation of a flood wave, in natural rivers, corresponds to the free surface flow equations in the Shallow Water case. The obtained two dimensional system, known as Saint Venant's system, is derived from the three-dimensional incompressible Navier Stokes equations by depth-averaging of the state variables. This system is written in a conservative form with hyperbolic homogeneous part. The discretization of the convection part is carried out by the use of the finite volume method on unstructured mesh. To increase the accuracy of the scheme, the MUSCL technique is used. The diffusive part is discretized using a Green-Gauss interpolation technique based on a diamond shaped co-volume. For the numerical experiment, we have studied a realistic channel of the Ourika valley which is located in Morocco. The flood occurred on August 1995 is simulated with the objective of evaluating the behavior of the wave propagation in the channel. The results of the proposed numerical model gives velocities and free surface elevations at different stopped times of the simulation

Simulation numérique d'écoulement compressible dans les joints labyrinthe

The labyrinth seals are the devices used machines which serve to restrict the leakages crossing a carter (or stator) by a rotating shaft (or rotor) and to avoid the important friction to high rotation speeds. These devices, which in addition behave as shaft bearings, can modify the dynamics characteristics of the line of the shaft in which they are integrated. The present work has been carried out with the purpose of controlling better the flows within the labyrinth seals and to determine their static (leakage-pressure) and dynamic (stiffness and damping coefficients) characteristics. It's based on the development of a global numerical model, and on the integration of the obtained correlations by 3D axisymmetric computation in this model.
Les joints labyrinthe sont des dispositifs utilisés dans les machines, ils servent à limiter les fuites à la traversée d'un carter (ou stator) par un arbre tournant (ou rotor) et éviter le frottement important aux vitesses de rotation élevées. Ces dispositifs, qui de plus, se comportent comme des paliers, peuvent modifier les caractéristiques dynamiques de la ligne d'arbre dans laquelle ils sont intégrés. Le travail présenté a été effectué dans le but de mieux maîtriser les écoulements dans les joints labyrinthe et de déterminer leurs caractéristiques statiques (débit-pression) et dynamiques (coefficients de raideur et d'amortissement). Il s'appuie sur le développement d'outils numériques intégrant dans les calculs globaux des résultats de calculs locaux (3D axisymétriques)