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МЕХАНИЗАМ ЗА КАЛИБРАЦИЈУ СОНДЕ СА ВИШЕ РУПИЦА ЗА МЕРЕЊЕ ПРОСТОРНОГ ПОЉА БРЗИНА И ПРИТИСКА У ВЕНТИЛАЦИОНИМ СИСТЕМИМА
No full textСимултана мерења сложених струјних поља брзине и притиска, и то са високом
учестаношћу, представљају вечити изазов за истраживаче широм света. Турбулентно
вихорно струјање на потису аксијалног вентилатора је један од таквих типова струјања.
Појава вихорног струјања у вентилационим системима, према бројним ауторима, представља
извор енергетских губитака, измештања пројектоване радне тачке вентилатора, као и
смањења енергетске ефикасности целог система.
За истраживање овако сложених турбулентних струјања, служе сонде са више рупица, попут
такозваних Конрад или кобра сонди. У новије време се трансмитери притиска уграђују у
носач сонде, па такве сонде имају брз одзив, односно велику брзину узорковања приликом
мерења. Брзина узорковања зависи од геометрије сонде. Сонда, која се приказује у овом
раду, може да узоркује са неколико хиљада одбирака у секунди, што је од изузетног значаја,
с обзиром на постојање изразито високог нивоа турбуленције брзине и притиска.
Нестационарност и трокомпонентност струјања, која је изражена код турбомашина, су
захтеви који доводе до геометрије сонде која има велики број рупица са уграђеним
трансмитерима високе учестаности. Ово је довело до производње FRAP (енг. Fast Response
Aerodynamic Probe) која имa 5 рупица и задовољава ове критеријуме. За разлику од
стандардних сонди (Пито), FRAP сонде је потребно редовно калибрисати.
Калибрација захтева испитивање сонде у аеротунелима са излазним млазницама довољне
величине и јако ниског нивоа турбуленције (до максимално 2%), при различитим угловима
наструјавања и брзина на главу сонде, и то у оквиру конуса јединствености сонде. Овако
сложена калибрација, која друго траје, даје, са друге стране, солидно велики комфор
приликом мерења са овим типом сонди.
Сви очекивани углови наструјавања сонде у њеним радним положајима при мерењима,
обухватају се тзв. Pitch-Yaw калибрацијом. Директан превод значи нагиб и скретање,
односно мењање углова φ и θ. Инсталације на ручни погон, које омогућавају ово закретање и
већ постоје у лабораторији Катедре за хидрауличне машине и енергетске системе, захтевају
превише времена, стрпљења и прецизности од експериментатора који врши калибрацију. Ово
доводи до потребе за аутоматизацијом целог калибрације сонде, што и јесте циљ излагања у
овом раду. Осим уштеде времена, аутоматизација нуди већи ниво тачности позиција и
прикупљања података са калибрисаног уређаја.
Пројектована инсталација се састоји од прецизног позиционера и аеротунела који има
задовољавајући ниво турбуленције. Цело управљање је написано помоћу програмског језика
LabVIEW који својим графичким приказом олакшава истраживачу управљање процесом
калибрације. Софтвер и инсталација су дизајнирани тако да омогућавају калибрисање и
других уређајa кроз даљу експлоатациј
SCALING OF HORIZONTAL STEAM GENERATOR BASED ON THREE-DIMENSIONAL THERMAL-HYDRAULIC SIMULATIONS
No full textThermal-hydraulics of horizontal steam generator (HSG) is numerically simulated and analyzed for the full-scale real HSG at the nominal 100% power built in the 1000 MWe nuclear power plant with the pressurized water reactor and for the scaled-down HSG design with all characteristic dimensions reduced to 50% of the full dimensions and operating at 12.5%, 15.7% and 18.7% of the 100% power of the real HSG. The scaled-down HSG designed is considered with the aim to investigate a design that suits the needs of a nuclear power plant with small modular reactor (SMR), which components should be manufactured in a factory and transported to and assembled at the power plant location. The several power levels of the scaled HSG are applied in the performed simulations in order to obtain steam void and water and steam velocities fields that should provide operating parameter values close to the proven safe and reliable values of the 100% full-scale HSG with mature operating experience. The simulations are performed with an in-house code based on the three-dimensional two-fluid model of two-phase flow and appropriate closure laws for the prediction of interface transport processes, such as vapour-liquid interface friction, vapour and liquid wall friction and liquid evaporation rate under thermal non-equilibrium conditions. The obtained results show a difference between geometry and power scaling. The 50% geometry reduction leads to about 80% of HSG power reduction
Wave propagation in tailored metastructures consisting of elastic beams and rigid bodies
No full textThis paper presents a study of wave propagation through an infinite periodic structure that consists of elastic Timoshenko beams interconnected with rigid bodies. This is a generalized approach in which the beams are not coaxial and the centre of mass of each rigid body is placed away from the intersection of their neutral axes. An analytical approach is used by applying the transfer matrix method (TMM), along with the Floquet–Bloch theorem for elastic wave propagation. Subsequent parametric analysis is performed with visualization of resulting band diagrams of a representative structure. These results are verified through comparison with solutions obtained using the finite-element method (FEM). In this manner, a comprehensive dynamical analysis of tailored metastructures is provided. This article is part of the theme issue ‘Current developments in elastic and acoustic metamaterials science (Part 2)’
Environmental and Social Assessment of SHPP Tearce Bistrica 1 – Expertise
No full textM103 - The expertise is done for Deloitte Consulting co. The investor was EIB (European Investment Bank)
Numerical Simulations for the Optimization of the Position of the Regenerative Burner System for Tundish Preheating
No full textThe paper presents the result of numerical simulations performed to optimize the position of burners and off-gas exit for a tundish preheating system. The optimization of the position of burner heads and off-gas exit at the tundish top cover has been done by application of StarCD CFD software for numerical simulations. 3D model of a tundish and its top cover consists of 300195 control volumes. Optimization of position for burner heads and off-gas exhaust at the tundish top cover brought a uniform temperature field inside the tundish refrac-tory layer during the transient preheating process with minimal fuel consumption
INTEGRATION OF ADDITIVE TECHNOLOGY AND MECHANICAL TESTING FOR THE ANALYSIS OF AUXETIC STRUCTURE CHARACTERISTICS
No full textThe Materials with a negative Poisson’s ratio are recognized as Auxetics materials. Compared to conventional materials it has the counter-intuitive property that during the compression the structure tends to contract and stretch when it expands. These particular attributes identified in the literature have encouraged further research on this topic. The flexible photopolymer resin is used for the test specimens, which have a cylindrical-shell based Auxetics structure. The test specimens are printed on an LCD printer with resin which gives structure
ductile properties during the compression test. Using an industry camera the dimensional changes are captured for further research. With Digital Image Correlation method experimental results show different scenarios in varying the dimensions of the structure. Analyzed results give a foundation for future research, giving it a special focus on improving the quality of future tests and giving a perspective of potential applications and manufacturing variations of Auxetics structures
APPLICATION OF 3D PRINTING IN ORTHOPEDICS
No full textThe integration of 3D printing technology into orthopedic practice addresses the critical problem of enhancing surgical precision and improving patient-specific treatment. Traditional orthopedic methods often involve generic implants and extensive preoperative planning, which can lead to suboptimal fit, prolonged surgery times, and varied patient outcomes. To solve this problem, patient-specific 3D anatomical models and custom implants can be used. High-resolution imaging data from patients can be converted into 3D-printed models, allowing for detailed preoperative planning and the creation of implants tailored to individual anatomical structures. This method also uses biocompatible materials and advanced printing techniques to ensure structural integrity and functionality. The use of 3D-printed models facilitated an enhanced preoperative understanding of complex anatomies, leading to reduced operative times and increased surgical precision. Customized implants result in better fit and integration with the patient's body, contributing to faster recovery times and higher patient satisfaction. Case studies indicate that this approach minimizes complications and optimizes overall orthopedic care. Despite promising results, challenges such as regulatory limitations, cost considerations, and the need for interdisciplinary collaboration remain. However, ongoing research and technological developments are expected to further refine these applications, paving the way for greater adoption and more widespread benefits in orthopedic practice
Energy efficiency within green solutions for management of water-energy-food-environment nexus
Get PDFEnergy efficiency is one of the most important research subjects in the process of optimal utilization of energy and water for food production, taking care of the environment. This is the requirement of efficient production and use of green renewable energy within the nexus water-energy-food-environment. Increasing number of inhabitants on the Globe require more energy, water and food. All technologies for energy, water and food production mast respect the criteria of environmental protection. The hydro, solar and wind energy are renewable resources and on the same time they are one of the most sustainable ways of electric energy production. Besides the benefit of clean green energy, the landscape of big solar or wind power plants, or big hydro accumulation and their impact on the environment mast also be the subject for analyses. The aspect of land occupying is a cutting edge research in correlation with the complex goal of using land for food production. This paper presents a green solution for management of the nexus water-energy-food-environment, using renewable resources