ISSN 2343–7707 ; ISSN-L 1453-7303

HIDRAULICA Magazine No. 2 / 2016

Hidraulica no.2/2016

Simulation of Turbulent Axisymmetric Waterjet Using Computational Fluid Dynamics (CFD)
Author: Nicolae MEDAN

This paper presents numerical simulation of axisymmetric turbulent free waterjet developed in water using RANS method with k-ε model. GAMBIT and FLUENT software has been used. There are presented graphs and contours for axial and radial velocities of waterjet, contours for the turbulence kinetic energy (TKE) and graphs representing the turbulence intensity (IT). There is briefly presented also the concept of computational fluid dynamics and methods developed for …. (read more)

Tribological Effectiveness of Graphene Oxide and Ionic Liquids in PAG Oil: Could Absorbed Water Play Beneficial Role?
Authors:Vincenzo D’AGOSTINO, Mario PISATURO, Claudia CIRILLO, Maria SARNO, Adolfo SENATORE

The polyalkylene glycol (PAG) lubricants are widely used as gear, bearing and compressor oils. Indeed, the base PAG oil can be used as additive in engine oil or transmission oil as well as compressor lubricant in refrigerant systems. They are designed to provide outstanding benefits in terms of efficiency, long oil life, and equipment protection. These fully synthetic lubricants were developed for use under operating conditions beyond the capabilities of other synthetic lubricants and mineral oils. Their low pour points ensure excellent low-temperature fluidity. On the other hand…. (read more)

Aerodynamic Protection of Wind Turbines
Authors: Mircea BĂRGLĂZAN, Teodor MILOŞ

In this work are presented the problems of aerodynamic protection of rapid axial wind turbines, with horizontal aggregate’s shaft. There are investigated in detail the interaction phenomena of wind (fluid flow) with aerodynamic shaped blades of the turbine runner. It is calculated for the realized wind power plants (designed by “Politehnica” University of Timişoara) the attack angles of fluid flow on the blade airfoils at different runner radiuses. Also it is determined the operation reserve without separation of the flow from …. (read more)

Water Supply Operating Rules in Parallel Dams by Means of Genetic Algorithms
Authors: Maritza L. ARGANIS, Rosalva MENDOZA, Ramón DOMÍNGUEZ, Gerardo ACUÑA

The Cutzamala system is the work of urban water infrastructure most important of Mexico since 1974, because it supplies drinking water to the Metropolitan Area of Mexico City with a flow rate of approximately 16 m3/s. The main dams of the Cutzamala system are: El Bosque, located in MIchoacan State; Valle de Bravo and Villa Victoria in the State of Mexico. In this analysis it was considered a parallel operation of these dams, i.e. independently feeding the water treatment plant Los Berros. A historical review was carried out considering, at each year, constant monthly extractions for each storage dam, genetic algorithms were then used to evaluate an objective function which … (read more)

Energy Use in Hydraulic Drive Systems Equipped with Fixed Displacement Pumps
Authors: Petrin DRUMEA, Catalin DUMITRESCU, Alexandru HRISTEA, Ana-Maria POPESCU

Using hydraulic drives has begun a long time ago, but in the 20th century they witnessed an outstanding expansion. Penetration of such systems in the field of complex equipment requiring high forces and speeds, provided with pumping units of 5 ÷ 500 KW, has represented an outstanding progress of hydraulics technology. Rather great progress, still not enough, has been done to reduce energy losses during use of fixed displacement pump systems. This paper is only the first part of a larger material which explores the evolution of …. (read more)

Electrical Analogy of Liquid Piston Stirling Engines
Authors: Aman GUPTA, Sunny NARAYAN

The use of fossils for of heat and power generation is a cause of concern due to emissions which are a great threat to human life. Solar and geothermal energy can be harnessed as renewable sources. According to second law of thermodynamics, theoretically maximum thermal efficiency is of Carnot cycle. However there are other cycles having advantages which includes liquid piston engine. This device is able to convert low-grade heat into hydraulic work. The basic principle of a Fluidyne is similar to a Stirling engine. This work deals with the dynamic modeling of liquid piston engines which is type of Stirling engine. Similarities between …. (read more)

CFD Analysis of a Wind Turbine Assembly Model
Author: Fănel Dorel ȘCHEAUA

The need for energy is growing worldwide today and hydrocarbon reserves are limited resources that are exploited at full capacity at this moment. Also noxious products released into the atmosphere due to the burning of hydrocarbons have harmful effects on the environment. Therefore the research activities and development of solutions for obtaining energy from renewable sources are fully supported in most countries with a high level of economic development. Such solutions are including the solar power, wave energy or wind force. Wind force generated by the movement of air masses between areas with pressure differential is an inexhaustible resource that can easily be converted into electricity in an environmentally friendly manner without the need of fuels combustion. To harness the energy produced by the movement of air currents many wind farms were developed, composed of … (read more)

Increasing the Efficiency of Wood Biomass Gasification Boilers
Authors: Gabriela MATACHE, Ioan PAVEL, Adrian PANTIRU, Marius CICIU

Increasing efficiency in combustion processes is set as a goal in all the research and innovation, energy and environment strategies. Gasification boilers work under nominal conditions while maintaining a temperature of about 200 °C along the smoke flue in order to avoid the deposition of coal tar.
This paper presents some solutions to increase efficiency of wood gasification boilers by recovering heat from the gas exhausted at the smoke flue (which otherwise would be lost to the atmosphere) and re-introducing it in the gasification or combustion air circuit. The energy thus re-introduced into the combustion process can increase efficiency of gasification boilers by a few percentage points, which means that …. (read more)

The Nuntași Riverbed Hydraulic Distribution Vector Speed
Authors: Mariana PANAITESCU, Fanel-Viorel PANAITESCU

In Romania, the current legislation provides normatives for knowledge, rational use, protection of water resources, and also organizes specific activities of defence against floods and supervises the quality of groundwater resources through prevention and control measures in case of accidental pollution.
These things we pursue in this paper which aims the assessing and hydraulic modeling of surface water environmental risk.
All abstractions of groundwater in South Dobrudja must be protected against pollution by setting up hydro and sanitary protection zones, in order to ensure …. (read more)

Environmental Awareness of Anthropogenic Impact
Authors: Carmen Otilia RUSĂNESCU, Gigel PARASCHIV, Sorin Ștefan BIRIȘ, Marin RUSĂNESCU

This paper presents awareness of pollution problems displayed by students of the Faculty of Biotechnical Engineering, future environmental engineers. Survey was conducted using a questionnaire consisting of five questions. It was noted that for the final year students is very important to protect the environment, this due to …. (read more)

Prediction of Turbulent Flow Using Upwind Discretization Scheme and k-ε Turbulence Model for Porous Heat Exchanger
Author: Petre OPRIŢOIU

The present investigation is concerned with the prediction of turbulent flow using upwind discretization scheme and k-ε turbulence model for porous heat exchanger application. Many modeling techniques exist for the analysis of porous foam. The Fluent porous media model employs a momentum equation which accounts for both viscous and inertial losses in the foam and includes …. (read more)

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