Wyniki wyszukiwania - BazTech

1

Aerodynamiczne kształtowanie bryły budynku

Szulc Jarosław, Sieczkowski Jan, Gołębiowski Łukasz

Builder

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2024

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R.28, nr 7

18--24

PL

Obserwowane ocieplenie klimatu, wywołane wzrastającą emisją CO2 do atmosfery, generuje powstawanie zjawisk klimatycznych o intensywnościach wykraczających niekiedy ponad wartości graniczne przyjmowane w kombinacjach oddziaływań przy projektowaniu obiektów budowlanych. W ostatnich latach w różnych obszarach Polski rejestruje się występowanie silnych wiatrów i gwałtownych trąb powietrznych. Wywołane przez nie szkody prowadzą do wielomilionowych strat ponoszonych przez budżet państwa, firmy ubezpieczeniowe oraz prywatnych właścicieli budynków. Straty obejmują zakresem infrastrukturę budownictwa mieszkaniowego, drogowego i energetycznego, zniszczenia dotykają również terenów zielonych i majątku ruchomego. Z tego względu konieczne stają się działania zmierzające do ograniczenia szkód wywołanych przez wiatr, np. poprzez właściwie opracowane plany zagospodarowania przestrzennego, odpowiednie kształtowanie bryły budynku i jego elementów oraz projektowanie i wdrażanie w wykonawstwie rozwiązań konstrukcyjnych przeciwstawiających się obciążeniom wywołanym również przez silne wiatry.

EN

Observed warming of the climate, caused by the impact of CO2 emissions to the environment, generates climatic phenomena with intensities sometimes exceeding the limit values adopted in combinations of actions when designing building structures. In recent years, strong winds and violent whirlwinds have been recorded in various areas of Poland. The damage caused by them leads to multi-million losses incurred by the state budget, insurance companies and private building owners. Losses include housing, road and energy infrastructure, damage also affects green areas and movable property. For this reason, it becomes necessary to take actions aimed at limiting damage caused by wind, e.g. through properly designed area development plans, appropriate shaping of the building body and its elements, as well as designing and implementing structural solutions that resist loads also caused by strong winds.

2

Aerodynamic investigation on the artefact “bird of Saqqara”

Zierow Michel, Lesemann Leon

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 3

405--409

EN

Lost, technical knowledge of ancient cultures is being rediscovered in modern times during archaeological excavations. A presumed example of the innovative power of ancient cultures is the artefact “Bird of Saqqara”. In the context of this paper, the aerodynamic characteristics of the artefact are to be determined by a computational fluid simulation, in order to be able to make a statement about the actual flight suitability and to examine the theses of the pre-astronautics critically. Based on a 3D scan, a CAD model of the artefact is created and then a numerical flow simulation is performed. By varying the angle of attack, the dimensionless coefficients can be represented in corresponding polars. The results show that the artefact has a low maximum glide ratio and thus the glide properties are not sufficient for use as a handglider. The centre of gravity of the artefact is located at the trailing edge of the wing and behind the neutral point. The resulting longitudinal stability does not meet modern specifications. Asymmetric lift distribution in the spanwise direction results in uncontrolled roll. Consequently, the artefact cannot fly a straight path. Within the scope of this work, the connection between the “Bird of Saqqara” and an alleged knowledge of aerodynamics in ancient Egypt could not be confirmed.

3

A CFD Study of the Aerodynamic Characteristics of Twardowsky and FOK Rockets

Sahbon Nezar, Murpani Siddharth, Michałów Maciej, Miedziński Dariusz, Sochacki Mateusz

Transactions on Aerospace Research

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2022

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Nr 1 (266)

35--58

EN

Stability and performance are crucial characteristics for aerospace vehicles. The ability to investigate the aerodynamics and performance of rockets gives an insight into their stability before flight and the potential for design and performance enhancements. For the past 13 years, the Rocketry Division within the students’ Space Association of Warsaw University of Technology has been developing sounding rockets of different designs and mission profiles. Two rockets have been chosen for the CFD (Computational Fluid Dynamics) campaigns, FOK and Twardowsky. This paper describes the mathematical model of aerodynamic loads used by the Division for sounding rocket simulation, followed by CFD campaigns for the two rockets. The results of the CFD analysis are then used to calculate the rockets’ aerodynamic derivatives according to a previously defined mathematical model.

4

Experimental study on Ahmed’s body drag coefficient

Wysocki Dominik, Szymanek Arkadiusz

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2022

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nr 25(1)

87--105

EN

The work presents an experimental designation of the aerodynamic drag coefficient for two configurations of the Ahmed body model, with slant angle of 25° and with the inactive synthetic jet generator. When analyzing the aerodynamic drag of vehicles, most authors focus on higher Reynolds numbers, describing lower values only by designated trend lines. Which is why the main contribution of this experimental work was to designate the Ahmed’s body drag coefficient for low Reynolds numbers and to verify the obtained results with other authors experiments especially with the trend lines for Reynolds number in the range 0,35x105 – 1,8x105. For data taken from the literature, it can be seen that the value of the drag coefficient for the Ahmed body model decreases when the Reynolds number increases. The results obtained during the experiment show the opposite tendency.

5

Building ventilation across history – examples

Gaczoł Tomasz

Przestrzeń i Forma

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2022

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nr 49

211--232

EN

Various cases from history indicate that the chimney is an important architectural detail in a building. Its shape, size and place where it rises above the roof affect the outline of a building and can even testify to the wealth of the family that inhabits it, as was the case in Portugal, among others. However, a chimney sometimes transforms from an architectural detail into a dominant element, which is not beneficial to the building’s overall massing. At present, ventilation is not only based on the design of ventilation ducts, but also on a comprehensive approach to design that affects the shaping of a building’s massing.

PL

Różne przykłady z historii świadczą o tym, że komin jest ważnym detalem architektonicznym budynku. Jego kształt, wielkość, miejsce wyprowadzenia ponad dach istotnie wpływają na sylwetę obiektu architektonicznego, a nawet świadczy o zamożności rodu zamieszkującego budowlę tak, jak to miało miejsce np. w Portugalii. Czasem jednak z detalu architektonicznego komin przeradza się w element będący dominantą, co nie jest korzystne dla całej bryły budynku. Obecnie wentylacja nie tylko polega na zaprojektowaniu przewodów wentylacyjnych ale również na kompleksowym podejściu do projektowania, mając wpływ na kształtowanie bryły obiektu.

6

Analiza wpływu układu konstrukcyjnego bomby kierowanej na charakterystyki aerodynamiczne

Wijaszka Mirosław, Milewski Wiesław, Klemba Tomasz

Problemy Techniki Uzbrojenia

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2022

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R. 51, z. 162

27--48

PL

W artykule zaprezentowano wyniki obliczeń charakterystyk aerodynamicznych oraz numerycznej symulacji lotu bomby korygowanej z wykorzystaniem laserowego systemu naprowadzania dla wybranych układów konstrukcyjnych bomb lotniczych. Dodatkowo obliczenia charakterystyk aerodynamicznych przeprowadzono z wykorzystaniem różnych metod obliczeniowych, a ich wyniki zestawiono i porównano. Do celów symulacyjnych ruch przestrzenny bomby opisano układem dwunastu równań różniczkowych zwyczajnych, które uzupełniono prawami sterowania. Podstawowym celem pracy była analiza wpływu układu konstrukcyjnego bomby na jej charakterystyki aerodynamiczne oraz wyodrębnienie cech aerodynamicznych właściwych dla układów konstrukcyjnych a predysponujących dany układ do zastosowania przy konstrukcji bomb kierowanych. W pracy przedstawiono przykładowe wyniki obliczeń.

EN

The paper presents results of calculations of aerodynamic characteristics and numerical simulations of flight of guided aerial bombs with a laser guiding system for their selected structural configurations. Moreover, the aerodynamic characteristics were calculated with different methods and the results were compared. A system of twelve differential regular equations supplemented by principles of steering was used to describe bomb’s spatial motion for simulation purposes. The main objective of the paper was the analysis of an influence which bomb’s structural configuration effects on aerodynamic characteristics and the identification of aerodynamic properties which are specific for these structural configurations and which could be preferred at designing of guided bombs. Exemplary results of calculations are presented in the paper.

7

Experimental Study of Air-Assisted Rocket System Models for Launching Payloads into a Low Earth Orbit

Frant Michał, Majcher Maciej, Omen Łukasz, Zalewski Piotr

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2022

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Vol. 13, Nr 3 (49)

67--82

EN

This paper presents the results of aerodynamic testing of air-launch rocket kit models for launching payloads into a low Earth orbit. The work was performed in a low-speed wind tunnel at the Military University of Technology (MUT, Warsaw, Poland)), using symmetrical airflow. Two carrier aircraft models were tested, i.e., Su-22 and MiG-29 aircraft without launched payloads and with these payloads at a dynamic pressure of q = 500 [Pa] and the range of angles of attack at α = -28° ÷ 28°. The values obtained related to the aerodynamic drag coefficient, aerodynamic lift coefficient, pitching moment coefficient and lift to drag ratio, and are given in tabular and graphic forms. The tests were primarily used to validate the numerical results obtained during implementation of the project “Air-assisted rocket system for launching payloads into low Earth orbit - feasibility study”.

PL

W pracy przedstawiono wyniki doświadczalnych badań aerodynamicznych modeli lotniczo-rakietowych zestawów do wynoszenia ładunków na niską orbitę okołoziemską. Badania wykonano w tunelu aerodynamicznym małych prędkości WAT w opływie symetrycznym. Zbadano dwa modele nosicieli – Su-22 oraz MiG-29 bez wynoszonych ładunków oraz z wynoszonymi ładunkami przy ciśnieniu dynamicznym q = 500 [Pa] w zakresie kątów natarcia α = -28° ÷ 28°. Uzyskane wartości współczynnika oporu aerodynamicznego, współczynnika siły nośnej, współczynnika momentu pochylającego oraz doskonałości aerodynamicznej przedstawiono w formie tabel i wykresów. Wykonane badania posłużyły przede wszystkim do walidacji wyników numerycznych, które były przeprowadzone w trakcie realizacji projektu „Lotniczo-rakietowy system wynoszenia ładunków na niską orbitę okołoziemską - studium realizowalności”.

8

Aerodynamic analysis of human walking, running and sprinting by numerical simulations

Forte Pedro, Sousa Nuno, Teixeira José, Marinho Daniel, Monteiro António, Bragada José, Morais Jorge, Barbosa Tiago

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 3

3--11

EN

The drag in walking, running and sprinting locomotion can be assessed by analytical procedures and experimental techniques. However, assessing the drag variations by the above-mentioned types of locomotion were not found using computational fluid dynamics (CFD). Thus, the aim of this study was two-fold: (1) to assess the aerodynamics of human walking, running and sprinting by CFD technique; 2) compare such aerodynamic characteristics between walking and running. Three 3D models were produced depicting the walking, running and sprinting locomotion techniques, converted to computer aided design models and meshed. The drag varied with locomotion type. Walking had the lowest drag, followed-up by running and then sprinting. At the same velocities, the drag was larger in walking than in running and increased with velocity. In conclusion, drag varied with locomotion type. Walking had the lowest drag, followed-up by running and then sprinting. At the same velocities, the drag was larger in walking than in running and increased with velocity.

9

Experimental Determination of the Impact of Floats on the Aerodynamic Characteristics of an OSA Model in Symmetric Flow

Frant Michał, Wrzesień Stanisław, Majcher Maciej

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2021

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Vol. 12, Nr 1 (43)

41--58

EN

This paper presents the results of experimental determination of the impact of floats on the aerodynamic characteristics of an OSA model in symmetric flow. The studies have been performed in the low-speed wind tunnel at the Military University of Technology (MUT, Warsaw, Poland). The aircraft model was examined at the dynamic pressure q = 500 Pa in the following angle of attack range α = -28⁰÷28⁰. The investigations have been performed for an aircraft model under plain configuration with floats and without floats. The influence of elevator and flap inclination on the aerodynamic characteristics of the model has also been analysed. The obtained values of aerodynamic drag coefficient, lift coefficient, pitching moment coefficient and lift-to-drag ratio have been presented in the form of tables and graphs. The studies performed demonstrated that the use of floats causes the increase of aerodynamic drag coefficient ϹD, maximum lift coefficient Ϲ Lmax as well as critical angle of attack α cr. The decrease of lift-to-drag ratio has also been observed. Its value in the case of the model with floats was up to 20% lower than in the model without floats. The studies also showed that the model equipped with floats had a lower longitudinal static stability margin than the model without floats.

PL

W pracy przedstawiono wyniki badań doświadczalnych wpływu pływaków na charakterystyki aerodynamiczne modelu samolotu OSA w opływie symetrycznym. Badania wykonano w tunelu aerodynamicznym małych prędkości WAT. Model zbadano przy ciśnieniu dynamicznym q = 500 Pa w zakresie kątów natarcia α = -28⁰÷28⁰. Badania wykonano dla modelu samolotu w konfiguracji "gładkiej" w wersji z pływakami i bez pływaków. Zbadano również wpływ wychylenia usterzenia poziomego oraz klap na podstawowe charakterystyki aerodynamiczne badanego modelu. Uzyskane wartości współczynnika oporu aerodynamicznego, współczynnika siły nośnej, współczynnika momentu pochylającego oraz doskonałości aerodynamicznej przedstawiono w formie tabel i wykresów. Przeprowadzone badania wykazały, że zastosowanie pływaków powoduje wzrost wartości zarówno współczynnika siły oporu aerodynamicznego, maksymalnej wartości współczynnika siły nośnej jak i wartości krytycznego kąta natarcia α kr. Zauważalny jest także spadek wartości doskonałości aerodynamicznej która dla modelu z pływakami jest nawet o 20% mniejsza od doskonałości uzyskanej dla modelu bez pływaków. Badania pokazały również, że model wyposażony w pływaki ma mniejszy zapas stateczności statycznej podłużnej niż model bez pływaków.

10

Validation of CFD predictions for flow over a full-scale formula student vehicle using PIV in real conditions

Wengrzyn Oskar

Journal of TransLogistics

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2021

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Vol. 7, nr 1

129--146

EN

Computational Fluid Dynamics (CFD) predictions are becoming an industry standard. They allow for making accurate predictions of complex problems without requiring extensive real-world testing, as well as saving time and money. However, it has been proven many times that the classic Reynolds-averaged Navier – Stokes (RANS) approach has its flaws and fails to provide highly accurate predictions. Even though CFD only approaches a physical solution, which can be reached only in very specific applications, it usually provides enough precision for engineering purposes. To reach a convergence with real-world physics, plenty of factors must be taken into consideration like mesh, boundary conditions, and turbulence models. In order to obtain a CFD simulation that accurately represents real physics, some kind of real-world validation must take place. For aerodynamics, it is usually done in wind tunnels, which are expensive to run but provide controllable conditions to match those specified in CFD. One of the many methods used to validate the calculations is Particle Image Velocimetry (PIV). This study tries to validate CFD of a Formula Student car using PIV, but in real-world conditions, without wind tunnel. The compact size of equipment required for PIV testing and flexibility of CFD boundary conditions allow for that.

PL

Prognozy obliczeniowej dynamiki płynów (CFD) stają się standardem branżowym. Pozwalają na dokładne przewidywanie złożonych problemów bez konieczności przeprowadzania rozległych testów w warunkach rzeczywistych, oszczędzając czas i pieniądze. Jednak wiele razy zostało udowodnione, że klasyczne podejście Reynoldsa uśrednione Navier-Stokes (RANS) ma swoje wady i nie zapewnia bardzo dokładnych prognoz. Mimo że CFD zbliża się tylko do rozwiązania fizycznego i może osiągnąć je tylko w bardzo specyficznych zastosowaniach, do celów inżynieryjnych zwykle zapewnia wystarczającą precyzję. Aby osiągnąć zbieżność z rzeczywistą fizyką, należy wziąć pod uwagę wiele czynników, takich jak siatka, warunki brzegowe i modele turbulencji. Aby mieć symulację CFD, która dokładnie odzwierciedla rzeczywistą fizykę, musi nastąpić pewnego rodzaju walidacja w prawdziwym świecie. Zwykle odbywa się to w tunelach aerodynamicznych, jeśli mówimy o aerodynamice, które są drogie w eksploatacji, ale zapewniają kontrolowane warunki, aby dopasować się do tych określonych w CFD. Jedną z wielu metod stosowanych do walidacji obliczeń jest Velocymetria obrazu cząstek (PIV). To badanie próbuje zweryfikować CFD samochodu Formula Student przy użyciu PIV, ale w rzeczywistych warunkach, bez tunelu aerodynamicznego. Umożliwiają to kompaktowe rozmiary sprzętu wymaganego do testów PIV i elastyczność warunków brzegowych CFD.

11

Wind tunnel tests of hovering propellers in the transition state of Quad-Plane

Pobikrowska Katarzyna, Goetzendorf-Grabowski Tomasz

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e138821

EN

The following paper presents wind tunnel investigation of aerodynamic characteristics of hovering propellers. This propulsion system may be applied on a lightweight Quad Plane VTOL (Vertical Take-Off and Landing) UAV (Unmanned Aerial Vehicle). A Quad Plane is a configuration consisting of a quadcopter design combined with a conventional twin-boom airplane. This kind of design should therefore incorporate the advantages of both types of vehicles in terms of agility and long endurance. However, those benefits may come with a cost of worse performance and higher energy consumption. The characteristics of a fixed-wing aircraft and propellers in axial inflow are well documented, less attention is put to non-axial flow cases. VTOL propellers of a hybrid UAV are subject to a multitude of conditions – various inflow speeds and angles, changing RPMs, interference between propellers and between nearby aerodynamic structures. The tested system presented in this article consists of four electric motors with two coaxial pairs of propellers mounted on one of the fuselage beams. Such a configuration is often chosen by designers of small and medium hybrid UAVs. There is a need for studies of clean, efficient ways of transporting, and this article can aid future designers of a new type of electric UAVs.

12

Rotorcraft thickness noise control

Szulc O.

Archives of Mechanics

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2021

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Vol. 73, nr 4

391--417

EN

The paper describes an innovative idea of Thickness Noise Control (TNC) based on adoption of a flow control strategy (i.e. surface ventilation) for acoustic attenuation of helicopter rotor periodic noise. The TNC method is relying on incorporation of multiple cavities (closed by perforated panels and linked to low- and high-pressure reservoirs) located in a symmetrical manner at front and rear portions of the blade tip. The efficiency of the new approach is verified using a two-bladed model rotor of Purcell (untwisted variant of the blade of Bell UH-1H Iroquois helicopter) in low-thrust hover conditions. The results of numerical simulations, obtained with CFD solver (Spalart–Allmaras turbulence and Bohning–Doerffer transpiration models), indicate that in the near-field of the blade tip, both the amplitude and spectral contents of pressure impulses of emitted thickness noise are significantly improved. The TNC method, in the proposed unsteady mode of operation, turns out to be a suitable means of thickness noise reduction in forward flight. Moreover, it is demonstrated that by proper azimuthal activation the efficiency is almost unaltered, while the rotor torque penalty and required transpiration mass-flux are decreased by a factor of 3–5 compared to a steady arrangement.

13

O współpracy Politechniki Opolskiej z Instytutem Mechaniki Teoretycznej i Stosowanej Akademii Nauk Republiki Czeskiej

Górski Piotr, Tatara Marcin

Inżynieria i Budownictwo

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2020

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R. 76, nr 7

351--356

PL

Przedstawiono wybrane rezultaty badań eksperymentalnych dotyczące wpływu oblodzenia na aerodynamikę cięgien mostów podwieszonych, które wykonano w kilku ostatnich latach w ramach współpracy dwóch ośrodków naukowych.

EN

The paper presents the selected results of experimental investigations on the influence of icing on aerodynamics of cables of cable-supported bridges. The investigations were carried out over the past few years within the framework of international cooperation between two partner scientific institutions.

14

Investigation of the Aerodynamic Drag Force Exerted on a Powerboat

Czyż Zbigniew, Karpiński Paweł, Boujelbene Chahin

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 3

141--148

EN

The aerodynamics of powerboats used in inshore powerboat racing has a significant impact on their performance. The aerodynamic drag forces generated on individual elements of this type of boats were tested. The solid model of the boat developed in the CAD software was used for the calculations. The computational grid was generated, as well as the boundary conditions and the turbulence model, were determined. On the basis of such assumptions, the numerical calculations were carried out using the CFD method. The results from the numerical simulations consist of a description of the velocity and pressure distribution around the tested object and identification of the drag force on the components of the powerboat with a description of the relationship between them. Additionally, the variation of the drag force as a function of speed in the range from 0 to 60 m/s was presented. The tests were performed for 5 values of the angle of attack of the boat to the surface of water in the range from 0° to 12°. The scope of the research allowed for the development of a drag force map depending on the defined parameters. The test results can be used to optimize the shape of the boat structure in order to reduce the aerodynamic drag generated on its individual elements.

15

A Concept of Live Fire Testing to Identify the Aerodynamic Coefficients of a 35 mm Anti-Aircraft Projectile

Baranowski Leszek, Gadomski Błażej, Majewski Przemysław, Szymonik Jacek

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

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2019

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Vol. 10, Nr 2 (36)

89--102

EN

This paper presents a generic algorithm designed to identify aerodynamic coefficients among the data specified in firing tables and projectile flight parameter data recorded during live fire tests. The algorithm and the concept of live fire testing shown here allow developing a mathematical model of projectile trajectory in the form of a modified motion model of a point mass. Potential applications of the model include fire control systems.

PL

W artykule zaprezentowano ogólny algorytm identyfikacji współczynników aerodynamicznych na podstawie danych zawartych w tabelach strzelniczych oraz na podstawie zarejestrowanych podczas strzelań poligonowych danych o parametrach lotu pocisku. Przedstawiony algorytm oraz koncepcja badań poligonowych pozwalają pozyskać model matematyczny ruchu pocisku w postaci zmodyfikowanego modelu ruchu punktu materialnego. Model taki może być wykorzystany np. w systemie kierowania ogniem.

16

Numerical investigation of the drag force reduction for homogeneous column of vehicles

Hamiga Władysław, Ciesielka Wojciech

New Trends in Production Engineering

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2019

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Vol. 2, Iss. 1

524--531

EN

This paper presents simulation studies on the aerodynamics of vehicles moving in an organized column. The object of research is a column that consist of three vehicles of the same type (homogeneous column). In this research geometry of Ford Transit was used. As a part of the studies, the air drag forces acting on individual vehicles were calculated. The results are presented in dimensionless drag coefficient. The influence of the distance between cars on the generated force was also determined. In the first stage of the work, a numerical model was developed based on the Ahmed body reference structure. The calculations were carried out for 9 different velocities. The obtained results of the drag coefficient were compared with the work of other authors. The applied turbulence model and parameters of the boundary layer were used to create a numerical model of a moving column of vehicles. Mesh independence for numerical model of van was verified. The Finite Volume Method was implemented in the ANSYS Fluent program and used for the calculations. The use of supercomputers was necessary due to the large size of the grid.

17

Numerical Analysis of the Influence of Particular Parts of the High Efficient Electric Vehicle on the Aerodynamic Forces

Czyż Zbigniew, Karpiński Paweł, Koçak Salih

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 4

1--7

EN

The work presents a three-dimensional modeling of air flow around the research object. The purpose of this work was to perform numerical calculations to identify the magnitude of the aerodynamic drag force generated on individual elements of a high energy efficiency vehicle body. This vehicle, specially designed for the Shell Eco-marathon competition, needs to show the lowest possible fuel consumption while maintaining the prescribed speed. Minimizing the drag force at an early designing stage plays an important role here. The calculations were performed using the ANSYS Fluent calculation solver. The result of the conducted research is a description of the velocity and pressure distributions around the tested vehicle as well as an identification of the drag force on the external surfaces of the components and a description of the relationship between them. The work also discusses the dependence of the drag force as a function of speed in the range from 0 to 12 m/s. The influence of the ground on the drag force in the case when the object was immobilized in relation to the walls at the flowing medium, as in a wind tunnel, was investigated. On the basis of the calculations performed, no impact of the ground on the generated drag force magnitude was found.

18

Composite body construction optimization and technological design of an electrically powered race car

Chatys R., Kuta K., Panich A.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2018

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z. 90 [298], nr 4

421--431

EN

The paper discusses the ways of structural optimization of composite automotive bodies, such as in race cars using electric and hybrid power sources. To reach these goals we were using CFD aerodynamic design check. Taking into account all the above mentioned issues, the integrated 3D-CAD race bolide body model prototype was designed, based on the concept of NACA profiles used in surface positive and negative curvatures generation to ensure better air overflow, stability, drag coefficient, downforce etc. The result of the integrated 3D-CAD race bolide body model is also presented as a real scale composite automotive body. This paper also discusses technological methods as well as problems and stages of real-life designing (from mould to ready composite part). The results can be useful for such consideration and on such issues as production and development of complex shape composite bodies, using readily obtainable and justified by cost-effectiveness materials and software.

PL

W artykule omówiono sposoby optymalizacji strukturalnej kompozytowych nadwozi samochodowych, takich jak samochody wyścigowe wykorzystujące elektryczne i hybrydowe źródeł energii. Aby osiągnąć te cele, korzystano z kontroli aerodynamicznej projektu CFD. Opracowano zintegrowany prototyp modelu nadwozia typu 3D-CAD oparty na koncepcji profili NACA, stosowany w generowaniu dodatnich i ujemnych krzywizn powierzchni, aby zapewnić lepsze parametry: stabilność, współczynnik oporu, siłę docisku itd. Rezultat zintegrowanego modelu nadwozia typu 3D-CAD z nadwoziem wyścigowym jest także prezentowany jako nadwozie kompozytowe w skali rzeczywistej. W artykule omówiono również metody technologiczne oraz problemy i etapy projektowania rzeczywistego (od formy do gotowej części kompozytowej). Uzyskane wyniki mogą być przydatne do produkcji złożonych brył kompozytowych, przy użyciu łatwo dostępnych i opłacalnych materiałów oraz oprogramowania.

19

Experimental study of the aerodynamics of sail in natural wind

Zeng X., Zhang H..

Polish Maritime Research

|

2018

|

S 2

17--22

EN

In order to evaluate the impacts of a motor vessel after installing wind sails, the aerodynamics of the sail should be accurately calculated. However most of the research on sails are based on stable wind instead of natural wind which is changing horizontally and vertically. In this paper wind tunnel tests are carried out based on stable wind field and simulated natural wind field, the results shown that there are 16–44% decrease in natural wind in terms of lifting coefficient and 11–42% decrease for drag coefficient. This would provide a valuable reference to the effectiveness evaluation of the impact of sails for sail assisted ships.

20

Modelowanie i symulacja numeryczna dynamiki zrzutu bomby korygowanej

Kowaleczko G., Pietraszek M., Grajewski K.

Modelowanie Inżynierskie

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2018

|

T. 35, nr 66

31--40

PL

W pracy przedstawiono proces modelowania dynamiki oraz wyniki symulacji lotu bomby lotniczej zrzucanej w warunkach spokojnej atmosfery. Opracowano model matematyczny ruchu przestrzennego bomby traktowanej jako bryła sztywna. W obliczeniach wykorzystano charakterystyki masowe i geometryczne opracowanej w Instytucie Technicznym Wojsk Lotniczych bomby ćwiczebnej LBĆw-10, którą poddano modernizacji w celu umożliwienia aktywnego sterowania jej lotem. Charakterystyki aerodynamiczne tej bomby określono, wykorzystując oprogramowanie PRODAS oraz na podstawie wyniku badań przeprowadzonych w tunelu aerodynamicznym. Pokazane przykładowe wyniki obliczeń numerycznych otrzymano z wykorzystaniem autorskiego oprogramowania.

EN

The paper presents a model of the bomb dynamics, which is dropped in calm weather conditions. The description of motion dynamics was based on the model of the rigid body and is dedicated to spatial motion simulation. The mass and geometric characteristics were referred to the LBC-10 training bomb, which had been developed at the Air Force Institute of Technology. Nowadays this bomb is modernized in order to enable the active control of the flight path. The aerodynamic characteristics of this bomb were determined using the PRODAS software and they were also based on the results of the wind tunnel tests. In the paper exemplary results of numerical calculations performed with the author's software are also shown.