ISSN 2343–7707 ; ISSN-L 1453-7303

HIDRAULICA Magazine No. 3 / 2020

Hidraulica no.3/2020

Wave Energy Recovery System Based on the Hydrostatic Principle
Author: Fănel Dorel ȘCHEAUA

Due to the certainly fact that the energy needs are constantly increasing at the present time, the handy production methods and also constituting environmentally friendly methods must be considered. Thus, processes and devices for energy production based on our planet renewable sources, constituted in water flows, solar energy, wind power and not at least the waves and tides force, have been continuously invented and developed. A solution for wave energy capture operating on the hydrostatic principle is presented in this paper. The solution particularity is represented by the operating principle of a constructive variant of wave energy recovery plant that has to be located directly on … (read more)

Modeling the Flow through the Wastewater Installation Bioreactor
Authors: Mariana PANAITESCU, Fănel-Viorel PANAITESCU, Nicolae-Marian IACOB

The paper presents the wastewater treatment processes circulating on board cruise ship and modeling the flow through … (read more)

Analysis of Vibrations and Noise in a Centrifugal Pump for Predictive Maintenance
Author: Sanda BUDEA

The article makes an analysis of the experimental results regarding the noises and vibrations that appear in the operation of a centrifugal pump, both on the pump and the electric drive motor, as well as on the elements of the installation. Noises and vibrations have both mechanical and hydraulic causes, in close connection with the flow rate of fluid or with the occurrence of … (read more)

Microwave Drying of Biomass
Authors: Roxana APOLZAN

Pilot studies were performed on the identification of drying conditions in the microwave field leading to the obtaining of dry biomass with humidity in the range of 5… 8%, starting from initial humidity of 14… 20%.
Sets of tests were performed with biomass sample masses of 5 and 10 kg for which the applied microwave power was varied, recording: variation of drying time with microwave power, average value of the final moisture in the sawdust (7.075, 60.6%) and variation of power density with drying time.
The existence of the direct relationship between the applied power density and the drying time allows(read more)

Considerations Regarding the Different Behaviour to Vibratory Cavitation Erosion-Corrosion of Brass and Bronze Used in the Cooling and Power Systems of Railway Engines
Authors: Iosif LAZĂR, Ilare BORDEAȘU, Gabriel Vasile URSU-NEAMȚ

Very many components operating in liquid environments are manufactured from copper-based alloys, i.e. brass and bronze. Most often, these alloys are selected based on their resistance to chemical corrosion and their high level of heat transfer capability. Some of these components are subject to cavitation stress. In consideration of the above, this paper presents the different resistances to vibratory cavitation erosion-corrosion of brass (CuZn39Pb3) and bronze (CuSn12-C) in semi-finished state, used to manufacture the components of valves installed in the cooling systems and hydrodynamic power transmission of railway vehicles. To show these differences in the behavior and resistance of the material when it is subject to cavitation microjets from the vibratory cavitation process, we are using SEM and photographic images of (read more)

Researches on the Development of a Nanobubbles Generator Used to Waters Aeration
Authors: Marilena Monica BOLTINESCU (ROZA)
, Nicolae BĂRAN, Mihaela CONSTANTIN

The paper presents a new type of air bubble generator that uses a plate with 900 nm orifices. Previous research has worked with fine bubble generators with orifices of 0.1 mm order. It is known that the smaller the orifices diameter, the smaller the bubbles immersed in water, so the water aeration will be more efficient.
Obviously, the constructive solution of the nanobubbles generator presented in the paper is clearly superior to (read more)

Numerical Modeling of River Embankment Local Failure under Accidental High-Waters Conditions
Authors: Marie Alice GHIȚESCU, Gheorghe I. LAZĂR, Albert Titus CONSTANTIN, Şerban-Vlad NICOARĂ

Exploitation in safety condition of flood protection hydraulic structures along watercourses is still an important problem, from economic and social point of view. The complex phenomenon of failure, an event of big importance for riparian areas, must be studied both in terms of genesis and development. In addition to exceeding the filling shear strength, the local failures of the river embankments are most often due to infiltrations through the body of the building, generating suffusions and leaks, respectively discharges over the canopy, generating progressive washing of the downstream facing of the filling. This paper presents a discrete 1D / 2D combined numerical modelling made with the help of the HEC-RAS v.5.07 package that simulates the hydraulic event on the Crasna River in the area of Craidorolț village, Satu Mare county, Romania, under the conditions of (read more)

Examining Centrifugal Pump BKS300 on Cavitation
Authors: Nikolett FECSER, Könözsy LÁSZLÓ, Nicolas LEDOS, Balázs SÁRA

Pumps influence all our lives directly or indirectly. Pumps are one of the most widespread types of turbomachines. Their task is to pump fluid from one place to another and engineers who are experts in pump technologies are familiar with the phenomenon of cavitation. The present work focuses on the cavitation from an experimental point-of-view. Measurements have been carried out on the type of a centrifugal pump. A polynomial fitting method has been developed and a semi-empirical formula has been proposed. Furthermore, numerical simulations have been performed for … (read more)

About the Contribution of Forest and Aquatic Ecosystems within Protected Areas to the Sustainable Development of Local Communities
Authors: Bogdan CIORUȚA, Mirela COMAN, Andrei Nicolae HELINDIAN

The EU’s vision for 2050 is to properly protect, enhance and restore biodiversity and ecosystem services provided by protected natural areas, considering the intrinsic value of biodiversity and the essential contribution of ecosystem services to human well-being and economic prosperity of the local community. Starting from this desideratum, through this paper we aimed to show that forest ecosystems, as well as aquatic ones, have an important role in the sustainable development of local communities if their contribution is properly assessed. We also want to emphasize that a ‘beneficiary pays’ policy is … (read more)

Press of Parallelepiped-Shaped Briquettes
Authors: Gabriela MATACHE, Valentin BARBU, Ioan PAVEL, Alina Iolanda POPESCU, Cristina Florina VOICU

The article analyses the basic elements necessary for the design of a press on which one can make medium-sized parallelepiped briquettes (150/60/60). First, the qualities of the raw material, the forest sawdust, the need and utility of making and using briquettes, as well as comparative elements with firewood are highlighted. The article presents a hydraulic solution of a medium sawdust briquette press and … (read more)

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