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The present study proposes a chlorination schedule calibrated for the Drinking Water Distribution Network (DWDN) of Buzau - a medium sized city, in South-Eastern Romania. The numerical model of Buzau's DWDN was set up in EPANET, considering the main pipes of the network that interconnect 4 pumping stations and 45 booster stations (viewed here as end-users). The calibration of the numerical model was based on real-time recordings available for January and July 2014. The chlorination scheduling was simulated at each reservoir supplying a pumping station, by a variable injection pattern added to the EPANET DWDN model. The injected amount of chlorine was determined by values of the chlorine concentration obtained at 4 key monitoring points, spread over the network. The simulations were performed over an extended time period of 72 hours. The system behaviour has been analysed for two cases: with all pumping stations in operation, and with the biggest pumping station shutdown. For each case, the proposed schedule corresponds to the injection in the network of less chlorine than the corresponding recorded values for January and July 2014, and yet obtaining at the 4 key points a chlorine concentration variation similar to the recorded one, while the chlorine concentration at the end users was within the admissible range, across the whole DWDN. [ABSTRACT FROM AUTHOR]

The paper deals with some aspects related to the shape of an indoor surfing platform for an aqua park. The authors have proposed a method and a strategy to modify the shape of the platform in order to be suitable for different types of surfers, beginners or advanced. The membrane is basically a water mattress consisting of 6 independent cushions attached to one another, that will allow different inflation pressures, hence different slopes on the upper surface of the elastic membrane. The scope of the paper is to provide an answer to the questions what is the inflation/deflation time of the mattress and what is the energy consumption for this operation. Thecomputationshave been conducted using EPANETfreewareand the results have shown a total time of initial expansion of more than 3 hours, an inflation/deflation time around two hours and one hour respectively. The total energy consumption resulted of about 2.4 kWh for the initial expansion stage and 1kWh for the inflation stage. [ABSTRACT FROM AUTHOR]

The paper deals with some aspects related to the shape of an indoor surfing platform for an aqua park. The authors have proposed a method and a strategy to modify the shape of the platform in order to be suitable for different types of surfers, beginners or advanced. The membrane is basically a water mattress consisting of 6 independent cushions attached to one another, that will allow different inflation pressures, hence different slopes on the upper surface of the elastic membrane. The scope of the paper is to provide an answer to the questions what is the inflation/deflation time of the mattress and what is the energy consumption for this operation. Thecomputations have been conducted using EPANETfreeware and the results have shown a total time of initial expansion of more than 3 hours, an inflation/deflation time around two hours and one hour respectively. The total energy consumption resulted of about 2.4 kWh for the initial expansion stage and 1kWh for the inflation stage. [ABSTRACT FROM AUTHOR]

The paper presents a comparison between the experimental and numerical results on the flow around a Bolund Island 1:705 scale model. A boundary layer wind tunnel with expansion stage was used for experimental modelling [9] . Velocity fields were determined using Constant Temperature Anemometry (CTA) and Particle image Velocimetry (PIV) measurements. Unsteady numerical simulations were performed using a Reynolds Average Navier Stokes (RANS) turbulence model adapted to atmospheric boundary layer flows [6] which was implemented in the ANSYS FLUENT expert software. At the beginning, the wind tunnel with expansion stage was explored and measurements were performed to determine the flow characteristics in the experimental vein. Data from CTA measurements in the median longitudinal plane, in eleven sections located at different distances from the expansion stage were used to determine mean velocity ant turbulence intensity profiles. Comparison with real data from the Bolund experiment showed a good agreement with the wind tunnel measurements. The experimental 1:705 scale model of the Bolund Island was manufactured on a CNC machine using the topographical data provided by the Risø DTU team from the Bolund experiment. Same data was used to build the mesh which virtually replicates the model placed in the experimental vein of the wind tunnel. PIV measurements were performed in order to determine the velocity, turbulence intensity and vorticity contours in a vertical reference plane and then compared to the URANS numerical simulation results. [ABSTRACT FROM AUTHOR]

The present case study points on the cooling water system of the Hydro-Power Plant (HPP) Bradisor, on the Lotru River in Romania. This 115 MW underground power plant is equipped with two Francis turbines. We built in EPANET a numerical model to simulate the operation of the cooling water system of this HPP, for different working scenarios. The whole hydraulic system is a complex one: it is composed of a main cooling water network fed by pumps, a water-based fire fighting network for the hydropower generators and a backup cooling water network fed from the penstock pipes. The numerical model of the whole cooling water system consists of 87 pipes, 133 junctions, 6 variable speed driven centrifugal pumps, 59 valves and 3 reservoirs. Some throttle control valves (TCV) are artificially inserted in our numerical model and are set with appropriate loss coefficients values to be equivalent to the equipments that introduce minor losses in the system and don’t exist as physical components in EPANET. Those equipments are: air-water heat exchangers (placed around the hydropower generators), oil-water heat exchangers (of heavy-duty thrust bearings, of turbines’ and generators’ guide bearings, of the 130 MVA step-up transformer), coolers of turbines’ seals and self-cleaning filters (one for each hydropower unit and another one for the transformer). The loss coefficient for each equivalent TCV was set based on pressure loss values measured in situ on each equipment. The numerical results (pressure and flow rate values) match the existing recordings. The simulations prove that by using a proper calibration of the numerical model, EPANET capabilities can be extended for more complex systems than the water distribution systems. [ABSTRACT FROM AUTHOR]

Our study points on a small groundwater well field of Arad City (Romania). We built in EPANET a model of the Mandruloc groundwater well field (13 wells). Due to the metering of the consumers, the demand dropped, so the well field is working at partial loads. We simulated the operation of the well field, by stopping 3 and 6 successive wells, placed at different positions. To avoid the wells overcharge, calculations were performed assuming that pumps run at variable speed. The proposed pumping algorithm gives better results with respect to a previous solution with orifice plates. [ABSTRACT FROM AUTHOR]

The case study points on the water distribution system (WDS) of Buzau City, a medium-sized city in South-Eastern Romania. We built a simplified numerical model of Buzau's main WDS in EPANET, which connects 4 pumping stations to 45 booster stations (end-users) and other users. The model was calibrated upon real-time recordings from 2014. The pumping scheduling is established upon control statements driven by the: discharge pressure of the corresponding pumping station; pressure levels at selected key points in the network (here, one pumping station can be shut down).Energy consumptions were calculated and compared with the current situation. [ABSTRACT FROM AUTHOR]

Pump operation control under variable system demand is obtained either by throttling the discharge pipe, by using by-pass pipes, by modifying the rotor speed, or by separating the pump and the demand by means of a pressurized tank. We try to assess the efficiency of pump operation control by using a numerical model created in EPANET for a 24 hours period. To avoid the demand driven algorithm used by EPANET, the network model consists of a throttle control valve followed by an emitter. Pump or valves parameters are modified using control statements. Results are consistent with the general theory. [ABSTRACT FROM AUTHOR]

A simplified numerical model of the water distribution network of a medium sized town (with 30,000 inhabitants), of elongated shape, was implemented in EPANET. The decay of chlorine residual concentration in the above mentioned network was studied, using the extended time analysis capabilities of EPANET, for a 3 days period. The water supply system, composed of one tank, 86 pipes and 52 nodes is driven by gravity. The chlorine is injected at the tank with a constant concentration amount. The variable water flow rates on the pipes of the network were modeled by means of a variable demand pattern, introduced at the end nodes of the system. The variation period of the demand pattern was set to 24 hours with a one hour time step. Water quality computation time step was set to 0.02 min, in order to ensure accurate prediction of chlorine concentrations, while hydraulic computation time step was set to 1 min. Both water quality and hydraulic analyses were conducted to depict the temporal variations of the flow rates, reaction rates, and chlorine residual concentrations in network's pipes and nodes. Pipe wall reactions and bulk flow reactions were modeled using both first-order and second order decay laws. The computed concentration values of the chlorine residual are above the lower admissible limit over the last 48 hours of the simulation period. The results obtained here for the decaying process described by the second order reaction law are trustworthy with respect to the ones obtained for the first order assumption. [ABSTRACT FROM AUTHOR]

Presents the results of studies carried out regarding the change of the atmospheric boundary layer. Two accepted recommendations regarding the velocity distribution at right angles to the ground level; Causes of the change of the atmospheric boundary layer; Focus on the change in the kinematics structure of the atmospheric boundary layer behind the snow fence.