Experimental Study of the Viscous Pump with a Helical Channel Rotor： Torsion Effect of the Channel

The viscous pump, which has a rotor with a helical square channel, is studied experimentally. The non-dimensional channel curvature is taken to be about 0.1. Three types of torsion of the channel are made to investigate the torsion effect on the flow characteristics. We measure the flux through the channel at a constant rotor speed by changing the pressures at the entrance and exit of the pump. We also observe the secondary flow at a crosssection of the channel. Some of the results obtained are shown as follows： The friction factor along the channel to get the same flux is large for large channel torsion at a constant rotation, and becomes small when the favorable rotation of the rotor to the flow is applied. As for the secondary flow in a cross-section, there appear several types of vortex. When there is no rotation, the secondary flow is almost a symmetric two-vortex type for small flux as is the ordinary Dean vortex, but it changes to a four-vortex type when the flux is large. The secondary flow becomes asymmetric as the rotation is applied. We have unsteady flow patterns at large flux and rotation.     

Laminar forced convection from a rotating horizontal cylinder in cross flow

The influence of non-dimensional rotational velocity, flow Reynolds number and Prandtl number of the fluid on laminar forced convection from a rotating horizontal cylinder subject to constant heat flux boundary condition is numerically investigated. The numerical simulations have been conducted using commercial Computational Fluid Dynamics package CFX available in ANSYS Workbench 14. Results are presented for the non-dimensional rotational velocity α ranging from 0 to 4, flow Reynolds number from 25 to 40 and Prandtl number of the fluid from 0.7 to 5.4. The rotational effects results in reduction in heat transfer compared to heat transfer from stationary heated cylinder due to thickening of boundary layer as consequence of the rotation of the cylinder. Heat transfer rate increases with increase in Prandtl number of the fluid.     

Prediction of dynamic and aerodynamic characteristics of the centrifugal fan with forward curved blades

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteris- tics based on numerical modeling. Three variants of geometry were investigated. The first, basic ＂A＂ variant con- tains 12 blades. The geometry of second ＂B＂ variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant ＂C＂ contains 24 blades without semi-blades. Numerical calculations were per- formed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine char- acteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also par- tially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calcula- tion stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.     

A Computational Study of Thrust Vectoring Control Using Dual Throat Nozzle

Dual throat nozzle （DTN） is fast becoming a popular technique for thrust vectoring. The DTN is designed with two throats, an upstream minimum and a downstream minimum at the nozzle exit, with a cavity in between the upstream throat and exit. In the present study, a computational work has been carried out to analyze the performance of a dual throat nozzle at various mass flow rates of secondary flow and nozzle pressure ratios （NPR）. Two-dimensional, steady, compressible Navier-Stokes equations were solved using a fully implicit finite volume scheme. The present computational results were validated with available experimental data. Based on the present results, the control effectiveness of thrust-vectoring is discussed in terms of the thrust coefficient and the coefficient of discharge.     

Study of Spiral Flow Generated through an Annular Slit

The effect of pressurized air inlets in the reservoir upstream of the annular slit on characteristics of the axial and tangential velocity components is investigated numerically, and the mechanism of occurrence of spiral nozzle flow is clarified. In simulations, Unified Platform for Aerospace Computational Simulation (UPACS) is used. The governing equations under consideration are the unsteady compressible Navier - Stokes. A second-order finite volume scheme with MUSCL (Roe scheme) is used to discretize the spatial derivatives, and a second order-central difference scheme for the viscous terms, and a MFGS (Matrix Free Gauss Seidel) is employed for time integration. Spalart-Allmaras model was used as a turbulence model. The results obtained are compared with velocity distributions in the experiment measured by the two-component fiber optic laser Doppler velocimeter system. The existence of discrete pressurized air inlets that leads to the occurrence of asymmetrical characteristics is a very important factor for the formation of spiral flow.     

Effects of Latitude and Design Variables on Performance and Cost of a Solar Heating System with Seasonal Storage

A thermo-economic model for the simulation and optimization of a CSHPSS （central solar heating plant with seasonal storage） is presented. The model, written in Matlab, allows to analyze the effects of different design and operating variables on plant performance and cost. Daily and seasonal variations of solar irradiation at different latitudes are considered, and an original approximate model for thermal stratification is included. Since a limited computational time is required, the simulation model can be effectively integrated with a non-linear constrained optimization procedure so as to determine the optimal choice of design variables for different locations and operating conditions. The comparison between a two-variable and four-variable optimization for five different locations at various latitudes has been presented, showing a significant decrease in pay-back time with latitude. Finally a sensitivity analysis on the most important design and operating variables has been performed and presented. It emerges that the optimal insulator thickness always decreases with latitude. The optimal tilt angle is slightly lower than latitude only when the plant is designed to cover the whole thermal load, while higher tilt values are selected in case of partial load covering.     

An Experimental Study of the Drag Force on a Cylinder Exposed to an Argon Thermal Plasma Cross Flow

Experimental data are presented concerning the drag force on a cylinder exposed to an argon plasma cross flow with temperatures about 10~4 K and velocities about 10~2m/s. Using a method of sweeping a cylindrical probe across an argon plasma jet, the total drag force on the cylinder can be measured as a function of the lateral distance of cylindrical probe with respect to the plasma-jet axis. Through the Abel inversion, the drag force for per unit of cylinder length and thus the drag coefficient of cylinder have been measured under plasma conditions and compared with the values obtained from the standard drag curve of the cylinder in an isothermal flow. Experimental results show that the measured drag forces are always less than their counterparts read from the standard drag curve with the same Reynolds numbers based on the oncoming plasma properties. The drag force on the cylinder exoposed to a thermal plasma flow is shown to be approximately proportional to the square root of cylinder diameter in the present experiment and it increases slightly with increasing surface temperature of the cylinder. It is also shown that applying a voltage between the drag probe and the anode of the plasma jet generator has little effect on the drag force of cylinder under the experimental conditions. The drag force on a cylinder with finite length exposed to an argon plasma with the axis parallel to the plasma jet is independent of ratio of cylinder length to its dismeter L/d for the cases when L/d≤1.     

The change of the inlet geometry of a centrifugal compressor stage and its influence on the compressor performance

The impact on the compressor performance is important for designing the inlet pipe of the centrifugal compressor of a vehicle turbocharger with different inlet pipes. First, an experiment was performed to determine the compressor performance from three cases: a straight inlet pipe, a long bent inlet pipe and a short bent inlet pipe. Next, dynamic sensors were installed in key positions to collect the sign of the unsteady pressure of the centrifugal compressor. Combined with the results of numerical simulations, the total pressure distortion in the pipes, the pressure distributions on the blades and the pressure variability in the diffuser are studied in detail. The results can be summarized as follows: a bent pipe results in an inlet distortion to the compressor, which leads to performance degradation, and the effect is more apparent as the mass flow rate increases. The distortion induced by the bent inlet is not only influenced by the distance between the outlet of the bent section and the leading edge of the impeller but also by the impeller rotation. The flow fields in the centrifugal impeller and the diffuser are influenced by a coupling effect produced by the upstream inlet distortion and the downstream blocking effect from the volute tongue. If the inlet geometry is changed, the distributions and the fluctuation intensities of the static pressure on the main blade surface of the centrifugal impeller and in the diffuser are changed accordingly.     

Fluid dynamic modeling of junctions in internal combustion engine inlet and exhaust systems

The modeling of inlet and exhaust systems of internal combustion engine is very important in order to evaluate the engine performance. This paper presents new pressure losses models which can be included in a one dimensional engine simulation code. In a first part, a CFD analysis is made in order to show the importance of the den- sity in the modeling approach. Then, the CFD code is used, as a numerical test bench, for the pressure losses models development. These coefficients depend on the geometrical characteristics of the junction and an experi- mental validation is made with the use of a shock tube test bench. All the models are then included in the engine simulation code of the laboratory. The numerical calculation of unsteady compressible flow, in each pipe of the inlet and exhaust systems, is made and the calculated engine torque is compared with experimental measurements.     

Effect of the uneven circumferential blade space on the performance of small axial flow fan

Effects of the uneven circumferential blade space on static characteristics and aerodynamic noise of a small axial flow fan are studied in this work.The blade angle modulation is adopted to design a series of unequally spaced fans,which have different maximum of modulation angular displacement.The steady flow is simulated by the calculations of Navier-Stokes equations coupled with RNG k-epsilon turbulence model,while the unsteady flow is computed with large eddy simulation.According to theoretical analysis,a fan with a maximum of modulation angular displacement of 6° is regarded as the optimal unequally spaced fan.The experiment of static characteristic is carried out in a standard wind tunnel and the aerodynamic noise of both fans is tested in a semi-anechoic room.Then,performances of the optimal unequally spaced fan are compared with those of the prototype fan.The results show that there is reasonable agreement between the simulation results and the experimental data.It is found that the discrete noise of the optimal unequally spaced fan is lower than that of the prototype fan at the near field monitoring point.This can be explained that the total pressure fluctuation of the optimal unequally spaced fan is much more regular than that of the prototype fan.     

Development of Breakup Model for Large Eddy Simulation of Diesel Spray

Diesel spray is injected at high pressure. So, upper stream region of spray is high Weber number condition. However, even if the fuel is injected at high pressure, the downstream region of spray is corresponding to relatively low Weber number condition. Thus, KH （Kelvin-Helmholtz） model modeled for high Weber number conditions and MTAB （modified Taylor analogy breakup） model are used for primary and secondary breakup processes respectively. This study is focused on the development of new hybrid breakup model The calculations are performed by LES （large eddy simulation） incorporated into KIVA code. LES of non-evaporating diesel spray are performed using KH ＆ RT （Rayleigh-Taylor） model, MTAB model and KH-MTAB model. Then, LES with these models were compared with experimental results. As the result, the availability of KH-MTAB model is showed. It is found that KH-MTAB is good agreement with experimental results of penetration and SMD （Sauter mean diameter） in relatively low density conditions.     

Implementation of the eddy dissipation model of turbulent non-premixed combustion in OpenFOAM

This work discusses the implementation of eddy dissipation model in OpenFOAM CFD toolbox. The code was validated in modeling of confined non-premixed Methane jet flame. The model predictions were extensively compared against published experimental results as well as ANSYS Fluent® predictions. The differences between the implemented model in OpenFOAM and Fluent were demonstrated.     

Integrating a simplified P-N radiation model with EdmFoam1.5: Model assessment and validation

This work compliments our recently published work of implementing the eddy dissipation turbulent combustion model in OpenFOAM [1]. The major update proposed herein is linking the EdmFoam1.5 solver with radiation modeling libraries in OpenFOAM. The new solver was validated against experimental data for jet and swirling Sydney flame (SM1). Each case was modeled with/without radiation modeling. The results have a fair agreement in general. In jet flame cases, the radiation modeling has a good impact on refining the predicted results. However it has not the same great effect on the swirling flame case. A review of the EDM applications in different reacting flow problems is also presented and discussed.     

Large Eddy Simulation of Normally Impinging Round Air-Jet Heat Transfer at Moderate Reynolds Numbers

This paper presents results of dynamic Smagorinsky-type model-based large eddy simulation of normally impinging round air-jet heat transfer at moderate Reynolds numbers (4,400, 10⁴, and 2.3 × 10⁴) with orifice-to-plate distance fixed at 5. Using software Open Source Field Operation and Manipulation (OpenFOAM), predicted distributions of mean velocity components, velocity fluctuations, and turbulent stresses in the vertical and radial directions are compared with existing empirical and numerical results. For the predicted heat flow from the target wall, there is satisfactory consistency of the mean Nusselt number in comparison with measured empirical results.     

Clever Nuclear Fuel Technology

The purpose of given article-consideration of the basic features of modern manufacturing of nuclear fuel which would confirm fact, that the manufacturer does everything that its production would respond not only to requirements of the consumer, but also to its expected inquiries, and would correspond to intended purposes of fuel. It was defined main tendencies and features of modern technology, especially in nuclear fuel production, on base of meeting discussions, themes of journal articles on nuclear subject. They are correspond with practice of JSC NCCP （Novosibirsk Chemical Concentrates Plant） and listed in the paper. In result of it number of base features of any advanced technology, not only nuclear, described here with examples from NCCP＇s practice. Of course, there is no certain list of all attributes of modern manufacturing as there is no limit to its perfection. These categories are forming by current needs of the market, but listed ones must be.     

Dynamic Voltage Restorer with Active Disturbance Rejection Control

Power quality is one of the major concerns among consumers and electric utility companies. CUPS （custom power systems） devices are used to improve the quality of power and enhance the reliability of the power supply in the distribution networks. The DVR （dynamic voltage restorer） is an important CUPS device used to mitigate voltage sag/swell and imbalances. Various control techniques have been implemented to control the DVR, among which the PID （proportional-integral-derivative） controller is dominant because of its model independent property and its error driven technique. In this paper, a new controller based on the ADRC （active disturbance rejection control） concept is developed, and its performance is compared to that of the PID controller. The model of the DVR and its ADRC and PID controllers were developed under the MATLAB （matrix laboratory）/Simulink environment. The simulation results demonstrated the effectiveness of the ADRC over the PID controller.     

Utilization of Data Communication according to the IEC61850 Standard for Nuclear Power Plant Electrical Equipment Testing

This paper deals with an integration of directly measured electrical parameters with data acquired by data communication from protections and terminals into an advanced monitoring system. Based on the periodic test, the authors of this paper present the possibility of an extended evaluation and more accurate analysis of transient and failure events. For periodical testing, as implemented during the commissioning of power plants in the Czech Republic, a monitoring system of electrical equipment has been used, to record the courses of important electrical parameters and thus, proving the proper functioning of complex technological systems in various operation modes. Data from monitoring system were used to prove the successful results of the test or as a base data for further analysis of failures. The monitoring system has proved itself as a very useful device also when recording unexpected failure events, the cause of which was very quickly and accurately detected by the follow-up analysis. Initially, only the voltage and current data from measuring transformers, analogue transducers and contact relays were used as input data for the monitoring system. After the implementation of new digital protection technology and controlling terminals with inner data recorder, the data from digital devices could be also utilized for the monitoring system.     

3D Conceptual Modeling and Direct Utilization Calculations of the Albanian Low and Middle Enthalpy Geothermal Resources

The use of the Albanian geothermal springs and waters, for their curative effects （Natural SPA） dates back centuries, since the time of the Roman Empire, while their first modern use started only in 1937. Unfortunately they had not been used for its energetic values yet. The temperature of the water is above 60 ~C and the flow above 16 L/s, thus direct utilization is possible, in particular for space heating. Three-dimensional temperature field calculations and engineering calculations on a heating system with heat exchangers are presented here. The results show that the water temperature is expected to be stable and considerably higher temperature is expected through deep well drilling. The University＇s Campus of Tirana is composed of 29 buildings, which are partially heated through a coal heater. The installed capacity is 2,558 kW while the coal consumption is about 920 kg/h. The University＇s Campus of Tirana is one of the most important areas and with the highest density of population in Tirana, so it is the best area to show the heat exchanger efficiency. The economic analyses prove that the borehole heat exchangers are more convenient than the coal heating systems.     

Counter-Rotating Type Tidal Stream Power Unit Moored by Only One Cable

The authors have proposed that a counter-rotating type tidal stream power unit mounted rigidly on a pile, and outputs of the power unit and forces acting on the pile were investigated experimentally at a previous paper, A single propeller makes the pile undertake a reaction force orthogonal to the stream direction. On the contrary, proposed counter-rotating propellers do not require undertaking the reaction force of the pile, because the rotational torque is counter-balanced in the unit. This advantage means that the unit can be moored by only one cable. Continuously, this paper proposes such a power unit with tandem propellers, and experimentally investigates a behavior of the unit floating in a water channel. The vibrations of the power unit are induced from not only the individual but also the interacting rotations of the front and the rear propellers.     

Numerical Flow Simulation in Turbine Mode of Counter-Rotating Type Pumping Unit to Cooperate with Wind Turbine

This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind circumstance. In this paper, the tandem impellers prepared for the counter-rotating type pumping unit were operated at the turbine mode, and the performances and the flow conditions were investigated numerically with accompanying the experimental results. Even though providing the pumping unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runners/impellers of the unit work evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet, without the guide vanes. From these results, it can be concluded that this type unit is effective to work at not only the pumping but also the turbine modes.