Wyniki wyszukiwania - BazTech

1

From Icing to Helipads: CFD-Based Solutions to Contemporary Rotorcraft Challenges

Dziubiński Adam

Transactions on Aerospace Research

|

2025

|

Nr 2 (279)

57--83

EN

This paper presents an overview of how computational fluid dynamics (CFD) has been used to address a range of engineering and operational challenges in rotorcraft development. Drawing on the author’s two decades of experience at the Łukasiewicz - Institute of Aviation in Warsaw, Poland, it highlights real-world applications of CFD in rotorcraft-related design and engineering. The case studies discussed include tail rotor icing in an unmanned helicopter, directional instability in a gyroplane, engine nacelle cooling in a modern helicopter, and airflow hazards near rooftop helipads in dense urban settings. Using multiphysics simulations, CFD helps reduce reliance on costly experiments, supports flight safety improvements, and informs regulatory decisions. The paper demonstrates the practical value of CFD as a tool in rotorcraft engineering and planning for urban air operations.

2

Analysis of the methods for decorating the skateboard decks using printing techniques

Cieślak Jakub, Godlewski Henryk, Podsiadło Halina

Polish Technical Review

|

2025

|

No. 2

19--25

EN

The popularity of skateboarding in Poland began to develop in the 1980s and is now a passion of several generations. The form of skateboards, the roots of which come from the USA, has been evolving since the 1960s. During this time, materials and production methods had improved. One of the production processes is making decorations on the skateboard decks, which make them distinguished and reflecting the brand. The discussed decorations are important in the context of distinguishing the product and matching the board to the user's character. Overprinting of skateboard decks is a sort of a challenge for printing industry because their surface is convex and bent. In order to overprint the entire surface of the deck, it is necessary to adapt classic techniques for this purpose or use dedicated devices.

PL

Popularność deskorolki w Polsce zaczynała się kształtować już w latach 80’ XX wieku i obecnie stanowi pasję kilku pokoleń. Forma deskorolki, której korzenie wywodzą się z USA, ewoluowała od lat 60’ ubiegłego stulecia. W tym czasie materiały i metody produkcyjne ulegały udoskonaleniu. Jednym z procesów produkcyjnych jest wykonanie zdobień na blatach deskorolkowych, które wyróżniają je i świadczą o marce. Zdobienia te są istotne w kontekście wyróżnienia produktu i dopasowania deski do charakteru użytkownika. Zadrukowanie blatów deskorolkowych to pewnego rodzaju poligraficzne wyzwanie, gdyż ich powierzchnia jest wypukła i ugięta. W celu zadrukowania całej powierzchni blatu konieczne jest dostosowanie klasycznych technik do tego celu, bądź zastosowanie dedykowanych urządzeń.

3

Analiza cieplno-wilgotnościowa złącza typu płyta na gruncie – mur

Ksit Barbara, Smoczyk Mateusz

Materiały Budowlane

|

2025

|

nr 1

63--64

4

Modelling the Heat and Mass Transfer in Devices with Dense-Layer Dispersed Systems

Krenický Tibor, Dyadyura Kostiantyn, Kokhan Olexandr, Umynskyi Serhii

Management Systems in Production Engineering

|

2025

|

nr 4 (33)

470--477

EN

The work is devoted to the processes of heat and mass transfer in moving and stationary dense layers of dispersed materials. One and two-component models of heat and mass transfer in a layer with internal heat sources caused by chemical and phase transformations in the presence of submerged heat exchange processes are given. A review of the literature showed that for a layer containing heat sources, not only information on these parameters is missing, but also methods for their determination. This paper describes the theoretical basis that forms the analytical dependencies of such methods. Satisfactory qualitative and quantitative agreement between experimental and calculated data indicates that the models accurately describe the main patterns of heat transfer in a blown layer with submerged heat transfer surfaces. The research results showed that when calculating temperature fields, reliable information is needed on the heat transfer coefficients of the layer and its components.

5

Numerical modeling of the solidification process in a mold-casting system with a gaseous gap

Węgrzyn-Skrzypczak Ewa, Skrzypczak Tomasz, Sowa Leszek

Journal of Applied Mathematics and Computational Mechanics

|

2025

|

Vol. 24, nr 1

69--77

EN

The paper focuses on the numerical modeling of the solidification process, with particular emphasis on the key physical phenomenon of heat transfer within the mold-casting system. This process is influenced by the presence of a gaseous gap, which introduces thermal resistance at the interface and affects the solidification rate. The numerical model is developed using the Finite Element Method (FEM), with separate spatial discretizations for both the casting and the mold. Additionally, the thermal expansion of these regions, caused by temperature-dependent volume changes, is accounted for. The model utilizes two distinct meshes to compute the evolving temperature fields. Heat exchange between the cast- ing and the mold is governed by boundary conditions linking the two regions. The solution is computed incrementally, with each region being solved independently at each time step. This paper describes the main assumptions of the mathematical and numerical models and presents the comparison of results of three simulation variants carried out using a custom- -built program.

6

Mostki cieplne we współczesnym budownictwie z perspektywy norm i przepisów prawa

Witek Arkadiusz

Izolacje

|

2025

|

T. 30, nr 7/8

56--61

PL

Detale konstrukcyjne występujące we współczesnym budownictwie poddano w artykule analizie pod kątem przenikania ciepła. Detale te dotyczą połączenia w ścianie jednowarstwowej, konsol w fasadzie wentylowanej, ciepłego montażu okien i masywnych pustaków z wkładkami izolacyjnymi. Pokazano, iż szacowanie zapotrzebowania na energię do ogrzewania obiektu o ścianach jedno- i wielowarstwowych, jedynie na podstawie współczynnika przenikania ciepła, może prowadzić do znacznego niedoszacowania wymaganej energii. Natomiast ocena strat ciepła przez konsole fasad wentylowanych wymaga obliczeń numerycznych przeprowadzanych z dużą starannością. Ciepły montaż okien nie wpływa na właściwości cieplne okna, ale zmniejsza ryzyko kondensacji pary wodnej (oprócz ograniczania strat ciepła na etapie obliczeń energii użytkowej). Natomiast rozpatrując właściwości cieplne elementów murowych o niesymetrycznej budowie, konieczne może być stosowanie analiz trójwymiarowych. Powyższe zagadnienia omówione są w artykule na przykładach obliczeniowych oraz z uwzględnieniem zapisów norm i przepisów prawa.

EN

The construction details found in contemporary civil engineering were analysed in the article in terms of heat transfer. These details concern the connection in a single-layer wall, consoles in a ventilated facade, insulating mounting frames of windows and massive blocks with insulating inserts. It was shown that estimating the energy demand for heating a building with single- and multi-layer walls, based only on the heat transmittance coefficient, may lead to a significant underestimation of the required energy. On the other hand, the assessment of heat losses through consoles of ventilated facades requires numerical calculations carried out with great care. Insulating mounting frames of windows does not affect the thermal properties of the window, but reduces the risk of water vapour condensation (apart from reducing heat losses at the stage of calculating the usable energy). On the other hand, when considering the thermal properties of masonry elements with an asymmetrical structure, it may be necessary to use three-dimensional analyses. The above issues are discussed in the article using calculation examples and taking into account the requirements of standards and law regulations.

7

Analiza rozwiązań materiałowych ścian zewnętrznych i ich złączy w aspekcie cieplno-wilgotnościowym - studium przypadku

Pawłowski Krzysztof

Izolacje

|

2025

|

T. 30, nr 10

48--56, 58

PL

W artykule przedstawiono przykładowe rozwiązania materiałowe jednowarstwowych, dwuwarstwowych i trójwarstwowych ścian zewnętrznych na bazie bloczków z betonu komórkowego. Wykonano obliczenia współczynników przenikania ciepła U z zastosowaniem zróżnicowanych układów materiałowych. Dodatkowo przeprowadzono analizę parametrów cieplno-wilgotnościowych wybranych złączy ścian zewnętrznych. Na podstawie przeprowadzonych obliczeń sformułowano wytyczne projektowe i wykonawcze w tym zakresie.

EN

This article presents sample material solutions for single-layer, double-layer, and triple-layer external walls based on aerated concrete blocks. Heat transfer coefficients U were calculated using various material systems. Additionally, the thermal and moisture parameters of selected external wall joints were analyzed. Based on the calculations, design and implementation guidelines were formulated in this regard.

8

Analiza porównawcza parametrów fizykalnych połączenia ściany zewnętrznej z płytą balkonową – studium przypadku

Pawłowski Krzysztof

Izolacje

|

2025

|

T. 30, nr 7/8

86--89, 90, 92

PL

Kształtowanie układów materiałowych złączy budowlanych powinno opierać się na analizie wyników obliczeń parametrów fizykalnych przy zastosowaniu programu komputerowego. W artykule zaprezentowano obliczenia w zakresie wpływu połączenia ściany zewnętrznej z płytą balkonową na parametry cieplno-wilgotnościowe. Przeprowadzono także ocenę analizowanych wariantów obliczeniowych w zakresie liniowego współczynnika przenikania ciepła Ψ oraz obniżenia temperatury na wewnętrznej powierzchni przegrody tsi,min. (występowania kondensacji powierzchniowej).

EN

The design of material systems for building joints should be based on the analysis of the results of calculations of physical parameters using a computer program. This article presents calculations regarding the impact of the connection between the external wall and the balcony slab on thermal and humidity parameters. An assessment of the analyzed calculation variants was also conducted in terms of the linear heat transfer coefficient Ψ and the temperature reduction on the inner surface of the partition tsi,min (the occurrence of surface condensation).

9

Considering uncertain quantities in the model of cryopreservation process of biological samples

Skorupa Anna, Piasecka-Belkhayat Alicja

Acta of Bioengineering and Biomechanics

|

2025

|

Vol. 27, no. 1

47--56

EN

This paper presents numerical modelling of the heat and mass transfer process in a cryopreserved biological sample. The simula-tion of the cooling process was carried out according to the liquidus-tracking (LT) protocol developed by Pegg et al., including eight stages in which both the bath solution concentration and temperature are controlled to prevent the formation of ice crystals. Methods: To determine the temperature distribution during cryopreservation processes, one uses the Fourier equation, while mass transfer was taken into account using an equation based on the Fick’s laws. This paper considers a model assuming fuzzy thermophysical parameters described by a triangu-lar and a Gaussian membership function. The numerical problem was solved using the finite difference method including fuzzy set theory. Results: The diagrams of temperature and mass distributions as a function on time and the distribution of the fuzzy variable at a given moment in time were prepared. Moreover, the fuzzy temperatures and concentrations were compared with experimental results from the literature in table. Conclusions: In the conclusions, two different types of membership functions were compared with each other, with which the fuzzy variables were described. It can be said that the Gaussian membership function works well for experimental data where the mean and standard deviation are known. In addition, the obtained results were confronted with experimental data. The calculated fuzzy temperatures are consistent with the temperature values occurring in the LT protocol. Larger differences between the experimental data and the calculated values are observed for the fuzzy dimethyl sulfoxide (DMSO) concentration.

10

Determination methods of boiling heat flux

Orman Łukasz J., Kapjor Andrej

Structure and Environment

|

2024

|

Vol. 16, no. 1

1--5

EN

Boiling is a phase-change phenomenon, which is of significant practical application potential due to large heat flux values exchanged in the process. The paper provides an overview of calculation methods that enable to determine the values of pool boiling heat flux on smooth surfaces. The most commonly used correlations were analysed and the boiling phenomenon occurring on smooth surfaces has been discussed based on the experimental data. A modification of the Rohsenow model has been proposed with the values of the constants determined experimentally.

PL

Wrzenie to zjawisko związane ze zmianą fazy czynnika, które ma znaczny potencjał praktyczny z uwagi na wymianę dużych gęstości strumienia ciepła. Artykuł przedstawia metody wyznaczania gęstości strumienia ciepła wymienianego przy wrzeniu. Analizuje najczęściej stosowane korelacje i opisuje zjawisko wrzenia, odbywające się na powierzchniach gładkich, w oparciu o badania eksperymentalne. Zaproponowano modyfikację modelu Rohsenowa zawierającą nowe wartości stałych eksperymentalnych.

11

Numerical Modeling of Thermal Energy Flow Compared with Data Obtained from an Experiment

Chodór Jarosław, Chomka Grzegorz, Orłowska Magdalena

Rocznik Ochrona Środowiska

|

2024

|

Tom 26

403--412

EN

The article presents the results of numerical analyses of temperature distribution and heat flow distribution in the building partition. The analysis results were compared with the results of the real object. A very good convergence of the results was observed.

12

Influence of Ventilation Air Supply into the Space Between Two Glass Units on the Energy Characteristics of this Transparent System

Basok Borys, Pavlenko Anatoliy, Novikov Volodymyr, Koshlak Hanna, Goncharuk Svitlana, Davydenko Dmytro

Rocznik Ochrona Środowiska

|

2024

|

Tom 26

65--73

EN

By the method of numerical simulation, the heat transfer from the room to the environment through a system of two double-chamber windows, into the gap between which ventilation air from the room supplies, is being researched. Distributions of air velocity and temperature in the chambers of double-chamber windows and in the gap between double-chamber windows are determined. The influence of the flow of ventilation air entering the space between the double-chamber windows on the amount of heat transferred from the room to the space between windows through the inner window and the amount of heat removed from the gap to the environment through the external double-chamber window is investigated. The energy advantages of the method of removing ventilation air through the gap between double-chamber windows over the method of direct removal of ventilation air from the room to the environment are determined.

13

Heat Transfer Through a Three-chamber Glass Unit

Basok Borys, Davydenko Borys, Pavlenko Anatoliy, Goncharuk Svitlana, Koshlak Hanna, Lysenko Oksana

Rocznik Ochrona Środowiska

|

2024

|

Tom 26

49--55

EN

A well-known way to increase the thermal insulation properties of windows in buildings is to increase the number of glasses in a window or, what is the same, to increase the number of glass chambers in a glass unit. This method, in combination with low-emissivity coatings on the inner surfaces of glass, can provide a significant increase in the heat transfer resistance of window structures. The use of such windows in construction can significantly reduce heat loss from the premises in the winter, which leads to a reduction in energy costs for heating and increases the energy efficiency of the building. In this work, the characteristics of heat transfer through a three-chamber glass unit are studied using numerical modeling and experimental study. Options for the absence and presence of low-emissivity coatings on glass are considered. Changes in air velocity and temperature in the chambers are studied. Heat transfer resistance for three-chamber windows are calculated depending on the number of low-emissivity coatings on the glass.

14

CFD Simulation of Heat Transfer Through a Window Frame

Basok Borys, Novikov Volodymyr, Pavlenko Anatoliy, Davydenko Borys, Koshlak Hanna, Goncharuk Svitlana, Lysenko Oksana

Rocznik Ochrona Środowiska

|

2024

|

Tom 26

56--64

EN

The use of various coatings with a low level of radiation on the glass elements of window structures, filling the interglacial space in double-glazed windows with inert gases instead of air, increasing the number of cameras in double-glazed windows, other constructive measures aimed at improving the thermal insulation properties of double-glazed windows, led to a significant increase in the thermal resistance of the fenestration system. However, little has changed in the design and construction of window frames and edge areas adjacent to building facades, leaving these elements responsible for heat transfer through modern windows. In this article, with the help of three-dimensional CFD modeling, the thermal insulation properties of window frames are investigated in the most complete setting, taking into account the effect on heat transfer through the profile of the window frame of the adjacent walls of the building facade on one side and the double-glazed unit on the other. Finding out the thermal insulation parameters of the window frame will help to make appropriate changes in its design.

15

Analiza numeryczna osiągów silnika rakietowego typu resistojet

Maleszyk Dawid, Kindracki Jan

Przemysł Chemiczny

|

2024

|

T. 103, nr 12

1527--1530

PL

Przedstawiono obliczenia numeryczne dotyczące silnika rakietowego typu resistojet. Silnik ten wyposażony jest w grzałkę elektryczną, która ogrzewa przepływający czynnik roboczy, dzięki czemu możliwe jest zwiększenie impulsu właściwego. Przedstawione analizy numeryczne silnika przeprowadzono dla różnych konfiguracji mocy grzałki oraz ciśnienia i rodzaju czynnika roboczego. Przedstawiono wizualizację przepływu oraz wymianę ciepła wewnątrz silnika, co stanowi istotną informację dla procesu optymalizacji pracy silnika, a także pozwala na wybór najlepszego czynnika roboczego.

EN

Numerical calcns. of a resistojet rocket thruster equipped with an electric heater that heats the flowing working medium were presented. Numerical analyses of the engine were performed for various configurations of heater power, pressure and type of working medium. Visualization of the flow and heat exchange inside the engine was presented, which provides important information for the engine optimization process and also allows the selection of the best working medium.

16

Numerical modeling of heat transfer and flow field in a novel calcinator

Zhou Tie-zhuang, Yang Bin, Wang Cheng-qiang

Polish Journal of Chemical Technology

|

2024

|

Vol. 26, nr 2

31--41

EN

This study focused on investigating the heat transfer and flow dynamics of a catalyst granule within a pilot calciner, employing both numerical modeling and computational fluid dynamics. The research comprised two primary components: (1) Simulation of the gas flow within the pilot calciner using the Eulerian–Eulerian approach, treating gases and catalyst particles as distinct phases – gas and granular. The model, encapsulating both heat transfer and flow processes, was developed in Fluent software version 16.0. Its accuracy was confirmed against empirical data from a pilot-scale calciner unit. (2) Subsequent to validation, the model was utilized to examine the distribution characteristics within the flow field, including the temperature profiles of gas and particles, the vector velocity field of the gas across different phases, and the overall heat transfer coefficient. This investigation aims to enhance the understanding of the complex heat transfer and flow dynamics in calciners, facilitating the optimization of operational parameters, performance, and structure of pilot-scale equipment. Furthermore, it provides foundational data pertinent to the future exploration of real-world industrial applications.

17

Optimization of Design for Air Type Evaporator Heat Exchanger

Skalski Tomasz, Ruciński Adam

Modern Engineering

|

2024

|

1

7--22

EN

This work provides an overview of air type evaporators, specifically focusing on coil type evaporators. It introduces a simplified method for calculating the required heat transfer area of a finned evaporator based on specified thermal and flow parameters, considering air and R134a refrigerant, as well as given design parameters. The study analyzes the influence of individual parameters on the heat transfer surface, using a base example as reference. Furthermore, it examines how changes in various system parameters affect the heat transfer surface. Such parameter analysis can aid in designing new heat exchangers and optimizing existing evaporators.

18

Numerical modeling of the casting solidification process in a mold taking into account the influence of an air gap with variable width

Węgrzyn-Skrzypczak Ewa, Skrzypczak Tomasz

Journal of Applied Mathematics and Computational Mechanics

|

2024

|

Vol. 23, nr 2

117--128

EN

The article presents a numerical modeling approach that utilizes the Finite Element Method (FEM) to simulate the solidification process of a casting in a mold. The study takes into account the local width of the air gap at each computational point on the interface between the casting and the mold. The developed numerical model provides a detailed understanding of the heat transfer between the casting and the mold during the solidification. The study shows that the air gap with variable width has a significant impact on the solidification process, affecting the cooling rate and the formation of the solidified region.

19

Przenikanie ciepła przez małe, niewentylowane pustki powietrzne w świetle obowiązujących norm

Witek Arkadiusz

Inżynieria i Budownictwo

|

2024

|

R. 80, nr 5

356--361

PL

W referacie omówiono szczegółowo i porównano procedury obliczeniowe z norm PN-EN ISO 10077 i PN-EN ISO 6946 stosowane do wyznaczania przenikania ciepła przez małe, niewentylowane pustki powietrzne. W celu praktycznej oceny różnic wykonano również obliczenia przykładowej pustki powietrznej programem komputerowym implementującym te metody. Na podstawie przeprowadzonych analiz wykazano szereg różnic w procedurach oraz zakres potencjalnych rozbieżności wyników, a zatem różnic w ocenach właściwości produktów wprowadzanych na rynek. Wykonano obliczenia dla przykładowej pustki powietrznej. Różnice strumieni ciepła wynosiły do 11% w zależności od zastosowanej metody.

EN

The paper discusses in detail the calculation procedures from the PN-EN ISO 10077 and PN-EN ISO 6946 standards used to determine the heat transfer through small, unventilated air cavities. In order to assess the differences in real situations, calculations of an exemplary air cavity were also performed using a computer program implementing these methods. On the basis of the analyzes carried out, a number of differences in procedures and the range of potential discrepancies in the results were demonstrated. Calculations were made for an example air void. The differences in heat fluxes were up to 11% depending on the method used.

20

Complex exponential method for solving partial differential equations

Pakdemirli Mehmet

Engineering Transactions

|

2024

|

Vol. 72, iss. 4

461--474

EN

For constant-coefficient linear partial differential equations solvable by separation of variables, an alternative solution method is proposed. The method employs complex exponential functions to find exact analytical solutions. Examples include the heat conduction equation, homogenous and non-homogenous wave equations, and the beam vibration equation. The method can be effectively used for partial differential equations (PDEs) whose solutions can be expressed as a product of harmonic and/or exponential type series.