Wyniki wyszukiwania - BazTech

1

Studies on the flame structure and drag of a combusting droplet group

Zhou Lixing, Li Ke, Sun Ting

Combustion Engines

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2023

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R. 62, nr 2

3--8

EN

Droplet combustion has been studied by experiments and numerical simulation for many years, and most of studies were done about single droplets. As for droplet groups, some theoretical and experimental studies were reported, but less of numerical studies. One of the important characteristics is the drag of combusting droplets, which is closely related to flame structure，and is a sub-model in numerical simulation of spray combustion. There are contradictory research results for the drag of combusting droplets. In the present paper, large-eddy simulation (LES) is used to study the flame structure and drag of a combusting ethanol-droplet group. The results show that there are three combustion modes: fully-enveloped flame, partially-enveloped flame and wake flame in a droplet group, leading to the change of the drag with inlet velocities. It is found that the drag of droplets in the group is much smaller than that of a non-combusting particle in isothermal flows.

2

Submarine Resistance Force Characteristics Determination After Modification of Depth Rudder System

Kiciński Radosław, Jurczak Wojciech

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 1

1--9

EN

A submarine, as a technical object, has many systems which are necessary for operation. In addition to the weapon systems, there are many systems required for the safe operation under the water. The submarine steering system is one of them. The article presents the principle of operation and the modification concept of the stern rudders of the project 207 (Kobben class) submarine. On the basis of measurements, the resistance force characteristics were determined. A calculation model was proposed using CFD (Computational Fluid Dynamics) and CAE (Computer Aided Engineering) techniques to determine the resistance force characteristics during the design stage. Then, the measured resistance force characteristics were used to verify the calculation model. Using the proposed method, the resistance force characteristics for an existing submarine were determined, and then its modification was proposed. The simulation results for the modified rudder design allowed determining the reduction of the ship resistance force for the new solution. Lower resistance force means lower demand for electrical power in the engine room, which consequently affects the operational safety by increasing maneuverability and improving the immersion curve. The proposed modification enables to reduce the power consumption by about 8 kW and reduced the resistance force by 2%, which increased the ship’s autonomy.

3

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.

4

Influence of the diffuser on the drag coefficient of a solar car

Mierzejewska P., Cieśliński A., Jodko D.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 2

509--519

EN

The purpose of the research was to design a solar vehicle for Bridgestone World Solar Challenge competition which takes place biannually in Australia. The article, however, presents the aerodynamic research on the car body, especially on the exit diffuser. Numerous CFD simulations of different diffuser shapes were performed in ANSYS CFX software. The paper presents the results of pressure distribution on the body and velocity contours. The drag force acting on the car body is dependent on the pressure distribution. The article includes comparison of corresponding drag coefficient values for different cases. Furthermore, the variation of the lift force depending on the shape of the bodywork was also taken into consideration. The research shows that slight differences in the construction of the exit diffuser correspond to noticeable changes in the drag coefficient values (0.138 minimum, 0.168 maximum) and significant changes in the lift force (minimum 71 N, maximum 160 N).

5

Zmodyfikowany model balistyki zewnętrznej dla naddźwiękowych pocisków moździerzowych

Magier M., Merda Tomasz

Problemy Techniki Uzbrojenia

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2017

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R. 46, z. 144

97--107

PL

W artykule przeanalizowano podstawowe modele stosowane do analizy i modelowania parametrów toru lotu pocisków. Na podstawie przeprowadzonej analizy autorzy zaproponowali zmodyfikowany model analizy parametrów toru lotu naddźwiękowego pocisku moździerzowego, bazujący na modelu o pięciu stopniach swobody z pomijanym szóstym stopniem swobody, którym jest prędkość obrotowa pocisku. W celu wyznaczenia współczynników wymaganych w zmodyfikowanym modelu wykorzystano metody CFD - program ANSYS FLUENT.

EN

Basic models applied for analysing and modelling the flight parameters of projectiles were disscussed in the article. A modified model with five degrees of freedom and neglection of the sixth one, representing the projectile rotation speed, is proposed by authors on the basis of conducted analysis to analyse flight parameters of a supersonic mortar projectile. To obtain the coefficients required in the modified model the CFD methods (ANSYS FLUENT software) were used.

6

CFD analysis of the air flow around the blades of the vertical axis wind turbine

Gavgali M. M., Czyż Z., Czarnigowski J.

Journal of Technology and Exploitation in Mechanical Engineering

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2017

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Vol. 3, nr 1

1--7

EN

The paper presents the results of calculations of flow around the vertical axis wind turbine. Three-dimensional calculations were performed using ANSYS Fluent. They were made at steady-state conditions for a wind speed of 3 m/s for 4 angular settings of the three-bladed rotor. The purpose of the calculations was to determine the values of the aerodynamic forces acting on the individual blades and to present the pressure contours on the surface of turbine rotor blades. The calculations were made for 4 rotor angular settings.

PL

W pracy przedstawiono wyniki obliczeń opływu wirnika turbiny wiatrowej o pionowej osi obrotu. Trójwymiarowe obliczenia wykonano za pomocą programu ANSYS Fluent. Obliczenia przeprowadzono w warunkach stacjonarnych dla prędkości wiatru równej 3 m/s dla 4 ustawień kątowych wirnika z trzema łopatami. Celem przeprowadzonych obliczeń było określenie wartości składowych siły aerodynamicznej działającej na poszczególne łopaty oraz przedstawienie konturów ciśnienia na powierzchni łopat wirnika turbiny. Obliczenia przeprowadzono dla 4 ustawień kątowych wirnika.

7

Air flow analysis around the autogyro fuselage

Czyż Z., Ilhan I., Akcay M., Czarnigowski J.

Journal of Technology and Exploitation in Mechanical Engineering

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2017

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Vol. 3, nr 1

13--20

EN

The paper presents the results of the simulation of the air flow around the gyroplane without the influence of the rotor and pusher propellers. Three-dimensional calculations were performed using ANSYS Fluent software. Based on the calculations, the values of the drag force and the lift force on each component of the rotorcraft were determined. Based on the results obtained, the effect of angle of attack on the aerodynamic forces was obtained.

PL

W pracy przedstawiono wyniki symulacji opływu modelu wiatrakowca bez wpływu wirnika nośnego oraz śmigła pchającego. Trójwymiarowe obliczenia wykonano za pomocą programu ANSYS Fluent. Na podstawie przeprowadzonych obliczeń wyznaczono wartości siły oporu oraz siły nośnej działające na poszczególne części składowe statku powietrznego. W oparciu o uzyskane wyniki otrzymano wpływ kąta natarcia na siły aerodynamiczne.

8

Determination of the forces affecting the particles and their trajectories in the surroundings of the matrix element in a magnetic separator

Goleman R.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 6

110--113

EN

In the paper, the forces and trajectories of paramagnetic and ferromagnetic particles moving in the surroundings of the ferromagnetic capture element of the matrix have been determined. The influence of the flow speed of the medium, the smooth section of the collector, the value of magnetic flux density and the properties of particles on the width of the collector’s particle capture zone have been analysed.

PL

W pracy zostały wyznaczone siły i trajektorie paramagnetycznych oraz ferromagnetycznych cząstek poruszających się w otoczeniu ferromagnetycznego elementu wychwytującego matrycy. Analizowano wpływ prędkości przepływu medium, smukłości przekroju kolektora, wartość indukcji magnetycznej i właściwości cząstek na szerokości strefy wychwytywania cząstek.

9

Ocena energetyczno-eksploatacyjna agregatów do uprawy przedsiewnej

Przybył J., Kowalik I., Dach J., Dworecki Z., Zbytek Z.

Journal of Research and Applications in Agricultural Engineering

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2012

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Vol. 57, nr 4

73-77

PL

Przedstawiono wyniki badań dotyczących oceny wybranych parametrów energetycznych i eksploatacyjnych dwóch agregatów do przedsiewnej uprawy wyposażonych w różne sekcje spulchniające. Określono opory robocze, a następnie moce uciągu i potrzebną moc efektywną ciągnika. Stwierdzono, że w zakresie wydajności i zapotrzebowania mocy agregaty nie różnił się istotnie od oferowanych na rynku produktów renomowanych firm zagranicznych.

EN

The study shows the results of energy and operation tests of two aggregates for pre-sow tillage, equipped in various loosening sections. Working resistive force have been established followed by the drawbar power and the required effective power of the tractor. We concluded that as for efficiency and power demand the aggregates do not differ significantly from the products of reputable foreign companies available on the market.

10

Heat loss optimisation in CNC motors

Mahdavinejad R.

Archives of Materials Science and Engineering

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2009

|

Vol. 35, nr 1

47-53

EN

Purpose: Heat loss plays very important role in CNC systems, especially in suspension systems with permanent load that are usually used for testing, detection and automatic cutting, the adjusting of motor torque in each axis is based on starting by maximum current required to overcome against resistant torque on the motion surface of the system. Design/methodology/approach: In this research a new control method is introduced for the minimization of heat loss in CNC motors. In these systems the misdirected current that causes magnetic misalignment and reduces the torque is converted to heat in the motor winding, thus reducing the motor continuous torque capability. Findings: This method is based on an open-architecture of a dynamic control to optimize the input current in order to dissipate the minimal heat loss. So that, it reaches the requested velocity-position condition with the lowest amount of misaligned magnetic field and current converted to heat. Research limitations/implications: The dynamic performance implications are more important than the steady-state torque disadvantage. Practical implications: An algorithm for the dynamic torque control is given and a simulation is carried out using this algorithm for a two axis CNC cutting system with two-guider bars suspension. Reaching to the actual requested motor current is practical implication. From this point of view, the enhanced free running of pulse width modulated (PWM) is represented. Originality/value: Results obtained in this work show that using the proposed procedure the heat loss is minimized while the speed errors are reduced and the surface finish is improved. Finally, the results of this dynamic control method is represented on CNC two axes cutting machine and extended the results on the other systems.

11

Siła oporu liniowego tłumika magnetoreologicznego

Sapiński B.

Czasopismo Techniczne. Mechanika

|

2004

|

R. 101, z. 5-M

313--324

PL

W niniejszym artykule dokonano analizy siły oporu liniowego tłumika magnetoreologicznego (MR). Rozważano zależności teoretyczne na siłę oporu i jej składowe, przyjmując uproszczony opis przepływu cieczy MR przez szczelinę tłumika w postaci modelu z płytami równoległymi. Przedstawiono wyniki pomiarów siły oporu tłumika na maszynie wytrzymałościowej oraz w semiaktywnym układzie zawieszeniu fotela kierowcy.

EN

The paper is concerned with the analysis of damping force for magnetorheological fluid damper (MR damper). Theoretical relationships for the restoring force and its components are discussed assuming a simplified for MR fluid flow through a parallel duct. Results of force measurements performed for a MR damper at a vibrating testing machine and in a suspension system for a driver's seat are presented.