ISSN 2343–7707 ; ISSN-L 1453-7303

Here below we post a list of
Papers already accepted for publication in Issue 2/2017 of HIDRAULICA.
The list displays paper title, author(s) and affiliation,
and also paper abstract.
Full-text paper will be available online only after publication.

  • Dynamics of Hydraulic Cylinders. Classical Mathematical Models and Simulations
    Prof. PhD Eng. Anca BUCUREȘTEANU
    University POLITEHNICA of Bucharest, Romania

    This paper presents mathematical models in dynamic mode for the study of hydraulic cylinders. It analyses the influence of the distributor type used for cylinder actuation but also the necessary correlation of pump flow, cylinder features and adjustment of pressure valve. The paper has a practical character because some unwanted dynamic aspects, such as, for example, the jerky start can be avoided since the designing phase of an installation.

  • Genetic Programming Applied for Shaping a Design Hydrograph from the Historical Flows’ Pattern
    Dr. Maritza Liliana Arganis Juárez1, M. A. Juan José Baños Martínez1,
    M. I. Margarita Preciado Jiménez2, Ing. Cecilia González Correa1
    1Universidad Nacional Autónoma de México, Mexico
    2 Instituto Mexicano de Tecnología del Agua, Mexico

    A method based on applying genetic programming (GP) in the ascending and the descending branch of a parameterized hydrograph is proposed in order to get a design hydrograph. Parameterization is done by considering peak flow, the peak time and the approximate time base estimated from the behavior of the annual maximum historical floods envelope and historical annual maximum floods envelope measured in the study site in the study site. With GP, was obtained the hydrograph’s behavior before and after the peak flow for the historical data. Additionally, was made comparison of the GP results with a polynomial interpolation of Lagrange. Afterwards a design hydrograph was obtained, for “El Infiernillo” dam, considering the peak design flow, calculated with the Instituto de Ingeniería (IINGEN) Method. The volumes approached with GP was different from that reported by the IINGEN Method, but this difference could be corrected applying a factor to the hydrograph ordinates, with exception of the peak flow to keep the volume. Hydrograph shape obtained using GP and the IINGEN method were similar, with smoothed shapes in hydrograph obtained with GP, but ensuring similar shapes than the historical floods, even the volume, peak and base time.

  • Examining the Characteristics of Pedrollo_CP130 Centrifugal Pump in Simulated Service Conditions
    Assist. Prof. PhD. Stud. Eng. Nikolett FECSER
    Széchenyi István University, Győr, Hungary

    In my study I examine the characteristics of a Pedrollo_CP130 centrifugal pump during operation. My choice of topic is justified by the facts that Pedrollo pumps have widely been applied, they are reliable and can be operated highly efficiently. Since their improper usage can cause problems, I decided to study the parameters of Pedrollo_CP130 pumps during operation to be able to avoid these problems. The fundamental characteristics of these pumps are flow rate, elevation head, power demand and efficiency. The monitoring of the pump’s characteristics is undertaken in the fluid dynamics laboratory in Széchenyi István University. The measuring device available in the laboratory is suitable for measuring the parameters of pumps. The whole measurement process is traceable on the screen belonging to the measuring device and the measurement parameters can be determined and the results can be recorded by computer software. In my study I describe the measuring device used in the hydrodynamics laboratory at Széchenyi István University. I give a description about the types of measurements available in the laboratory and show the measurement results carried out by a Pedrollo_CP130 pump, the correlations determined from them and the conclusions taken from the measurement. The outcomes of my study can be beneficial when we operate pumps of similar types.

  • Vector Estimation of Centrifugal Force and CAD Techniques for Protection Mechanism at Over-speed of the Low-power Wind Turbine Rotor
    Assoc. Prof. PhD. Eng. Teodor MILOȘ, Prof. Em. PhD. Eng. Mircea BĂRGLĂZAN,
    Lecturer PhD. Eng. Rodica BĂDĂRĂU
    University POLITEHNICA of Timisoara, Romania

Rotor over-speed protection for small power wind turbine requires a possible cheap and reliable mechanical system. This is because any electric or electronic device depends on the electrical power source which by an electrical damage becomes unavailable. Between these protection devices centrifugal mechanism is priced at acceptable cost, but contains some subtleties of interpretation of the mode of operation. In this paper, it is explained step by step the original solution of this mechanism put in place for a 5 kW wind turbine. After triggering the centrifugal mechanism, the rotor blades are rotated to the flag position producing aerodynamic braking of the rotor. The speed is reduced to 20 … 30 rpm, after which the action of the centrifugal mechanism is greatly reduced (centrifugal force decreases) so that the force in the compressed spring plus the aerodynamic torque of the blades relative to the axis of the blade spindle causes the return to the initial working position. Adjusting ballast weight of centrifugal mechanism and the reliable automatically operation of the whole system should be tested repetitively on an endurance stand.

  • Assessing the Hydro power Potential of Bistrita River
    Prof. PhD.Eng. Mariana PANAITESCU, Prof. PhD.Eng. Fanel-Viorel PANAITESCU
    Constanta Maritime University, Romania

The aim of the paper is the study of the Bistrita River from the point of view of water. It proposes a linear representation of the specific synoptic potential and graphical representation of water cadastre. The calculation is done on each sector and it follows the steps: sector fall, average flow per sector,  theoretical power sector, theoretical energy sector, sector length, specific theoretical linear potential of the k sector and the specific power. Using specific software for the representation of the theoretical linear synoptic potential and analyzing the water cadastre representation, one can notice that the maximum amount of hydro power potential is achieved on one specific sector. Therefore, it is most suitable for hydro power facilities.

  • Optimizing the Equation of Impact Forces Produced by Water Jets Used in Sewer Cleaning
    PhD. Eng. Nicolae MEDAN, PhD. Student Eng. Adrian Paul BASARMAN
    Technical University of Cluj-Napoca, North University Center Baia Mare, Romania

The purpose of this paper is to optimize the equation of the impact forces produced by water jets used in sewer cleaning. The functioning of the cleaning sewer is dependent on certain process parameters, which can vary, causing variations of the impact forces. The research method used is Taguchi design of experiment. To be able to make the experiments there was used a stand to generate the water jets and a device to measure the impact forces. In the first part of paper there was determined the percentage of influence of parameters involved in the process and then there was developed a multiple linear regression model in three different ways to optimize the prediction of the proposed equation.

  • Possibilities for Agricultural Farms of Adopting and Applying Optimal Energy Recovery Solutions from Nearby Water Flows
    Assist. Prof. Fănel Dorel ȘCHEAUA
    “Dunărea de Jos” University of Galati, MECMET Research Center, Romania

Today, must be highlighted the increase of energy needs according to continues population growths worldwide. That is why it should be increasingly used the possibilities of energy obtaining by optimizing the resources at hand. These clean resources that do not have a major impact on the environment, are represented by water falls and flows. These resources are among the most advantageous in terms of obtaining the electrical energy by converting the mechanical energy obtained by the flowing water from a river. A method of obtaining electric energy based on the water flow power is presented in this paper. It is about a mini-hydroelectric power system that can be achieved and mounted on a water body with a lower water flow rate, with the ability to supply power for an nearby agricultural farm. Based on the continuous water stream flow a rotational motion is carried out at the helicoidally rotor shaft which is connected to a power generator thereby achieving the mechanical energy conversion into electrical energy with optimal results for producing continuous electric energy. The water intake assembly system consisting of water channel and the helicoidally rotor it has been modelled as a three-dimensional model, on which an flow analysis has been made in order to highlight the distribution of fluid flow from the inlet to the outlet of the supply channel of the hydroelectric plant model. The obtained results are presented in terms of fluid velocity across regions and specific pressures appearing on the fluid region in which the helicoidally rotor of the system is immersed.

  • Comparative Study of the AWJ Cutting Geometry using the 3D Point Measuring Method versus 3D Scanning of the Surfaces
    PhD. Stud. Eng. Adrian P. BASARMAN, PhD. Eng. Nicolae MEDAN
    Technical University of Cluj-Napoca, North University Center at Baia Mare, Romania

The abrasive waterjet cutting (AWJ) method is a modern and very a useful technology cause it uses a different technique of cutting the material, more different than the classic way of cuting in which a tool takes contact with the part that needs to be cut. In order to asses the surface resulted after cutting, the kerf width, the surface has to be analysed on both sides of the cut, both on the part and the counterpart. In this paper it is presented a comparative study on a C45 part cutted using AWJ and, the surface resulted is first measured using a 3D measuring arm that measured the surface in points per surface and, second, using a more modern technology, the 3D scanning device. The same surface has been measured with this two different technologies and the results are compared and presented in this paper.

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