Кафедра екології, теплотехніки та охорони праці (ДМетІ)

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ENG: The department of Ecology, Heat-Transfer and labour protection (DMetI)

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Analysis of CFD Modelling Results of Designed Uniflow Vortex Tube Models
(Energetická konzultačná agentura n.o., Prešov, Slovak Republic, 2025) Muzychka, Ihor; Kizek, Jan; Menkov, Andriy; Karakash, Yevhen O.; Kulikov, Andrii
ENG: This study presents the results of CFD modelling of a uniflow Vortex tube based on the Ranque-Hilsch effect. The designed models are based on experimental measurements and calculations presented in [1], with the calculations derived from relationships published by Takahama [2] and Soni [3]. The tube geometry was designed according to these relationships for an inlet pressure of 0.5 MPa, which was also used in the CFD simulations. Two different inlet air geometries were tested. The analysis focused on velocity and temperature fields in the developed mathematical models. The results will serve as a basis for the design of experimental devices.
Development of a Mathematical Model for the Energy Balance of the Laser Cladding Process of Metallic Powders with a Coaxial Nozzle
(MM Publishing s.r.o., Praha, Czechia, 2024) Karakash, Yevhen O.; Rimar, Miroslav; Karpovych, Olena; Zhumar, Denys; Kizek, Jan; Fedak, Marcel; Kulikov, Andrii
ENG: Modern technologies require innovative solutions for producing complex structures from various materials. Additive manufacturing (AM) or 3D printing presents such a challenge and has significantly impacted the environment across manufacturing sectors, regardless of size. Researchers and technicians have developed new design approaches by exploring fundamental components, materials, and manufacturing processes beyond traditional frameworks, addressing global complex material and design challenges. Laser cladding of metal powders with a coaxial nozzle is one such technology, offering highly productive processes for large-scale component production. Fiber lasers are optimal for providing laser radiation, ensuring required emission quality and stability. The authors seek to develop a mathematical model for the energy balance of coaxial laser cladding of metal powders, aiming to provide an overview of energy consumption levels and unit characteristics for powder delivery, inert gas, and laser radiation sources in direct metal powder coating setups.
Modeling of Thermal Processes in DED Using SolidWorks Simulation
(Energetická konzultačná agentura n.o., Prešov, Slovak Republic, 2024) Karpovich, Olena; Zhumar, Denys; Karakash, Yevhen O.; Karpovich, Ivan
ENG: The study analyzes software products for numerical modeling of additive processes performed using SLM and DED technologies. Determining temperature fields in DMD processes is an important and complex task. Based on previously determined experimental data on the volume of molten material added during cladding, the thermal processes during laser cladding of powder materials were modeled in the SolidWorks system. This allowed determining the distribution of temperature fields on the substrate and in the cladded material over time.
Structural Analysis of Joints Made of Titanium Alloy TI-6AL-4V and Stainless Steel AISI 321 with Developed Conical Contact Surfaces Obtained by Diffusion Welding
(MDPI, Basel, Switzerland, 2025) Karpovych, Olena; Karpovych, Ivan; Fedosov, Oleksii; Zhumar, Denys; Karakash, Yevhen O.; Rimar, Miroslav; Kizek, Jan; Fedak, Marcel
ENG: The object of this study is welded joints of AISI 321 and Ti-6Al-4V, obtained by diffusion welding on developed conical surfaces. The problem of creating bimetallic joints of AISI 321 and Ti-6Al-4V with developed conical contact surfaces, using diffusion welding through an intermediate Electrolytic Tough Pitch Copper (Cu-ETP) copper layer, was solved. The joints were studied using micro-X-ray spectral analysis, microstructural analysis, and mechanical tests. High mutual diffusion of copper and titanium, along with increased concentrations of Cr and V in copper, was detected. The shear strength of the obtained welded joints is 250 MPa and 235 MPa at 30 min and 15 min, respectively, which is higher than the copper layer’s strength (180 MPa). The obtained results are explained by the dislocation diffusion mechanism in the volume of grains and beyond, due to thermal deformations during welding. Under operating conditions of internal pressure and cryogenic temperatures, the strength of the connection is ensured by the entire two-layer structure, and tightness is ensured by a vacuum-tight diffusion connection. The obtained strength of the connection (250 MPa) is sufficient under the specified operating conditions. Analysis of existing solutions in the literature review indicates that industrial application of technology for manufacturing bimetallic adapters from AISI 321 stainless steel and Ti-6Al-4V titanium alloy is limited to butt joints with small geometric dimensions. Studies of the transition zone structure and diffusion processes in bimetallic joints with developed conical contact surfaces enabled determination of factors affecting joint structure and diffusion coefficients. The obtained bimetallic adapters, made of Ti-6Al-4V titanium alloy and AISI 321 stainless steel, can be used to connect titanium high-pressure vessels with stainless steel pipelines.