Wyniki wyszukiwania - BazTech

1

Numerical study of heat transfer and aerodynamic drag of the radiator with lamellar split finning

Nikolaenko Yurii, Baranyuk Aleksandr, Rohachov Valerii, Terekh Aleksandr

Archives of Thermodynamics

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2020

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Vol. 41, no 1

67--93

EN

Promising cooling systems for high-power electronic elements are those based on vapor chambers and heat pipes which allow for the local heat flow to be dispersed from the electronic element to a larger surface area of the vapor chamber or the heat pipe. To reduce the thermal resistance of the cooling system, a finned radiator is installed on the outer surface of the vapor chamber or heat pipe. The authors propose a new design of the radiator which increases the heat transfer efficiency. The paper presents results of numerical simulation of heat transfer and aerodynamic resistance of the heat transfer surface with lamellar-split finning. The comparative analysis of heat transfer and aerodynamics was carried out for three types of radiators: with lamellar smooth finning, with lamellar split finning and with the sections of split finning rotated 30◦ against the air flow. It is shown that cutting the fins and rotating the split sections leads to an increase in heat transfer intensity and increase in aerodynamic resistance. The obtained results may be useful in the design of cooling systems for computer processors, power amplifiers for transmitting modules, energy-saving solid-state light sources, etc.

2

Aerodynamics of articulated multilink trucks

Andreihyk A., Kharytonchyk S., Kochetov S., Shmelev A.

Journal of KONES

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2018

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Vol. 25, No. 3

25--32

EN

Development of new generations of supersize heavy-duty highway trucks for cargoes transportation on long and super long distances between Europe, Asia and Far East is actual now. New trucks shall reduce amount of transport on roads and quantity of drivers, involved in the transportation, will raise economic efficiency and safety of transportations and reduce fuel consumption, CO2, and harmful emissions. Multilink trucks (number of trailed links is three and more and the total truck length is above 40 m) are to achieve designated purposes and thus are under the scope in the article. The advantages of multilink trucks are formed mainly by reducing the cost of power to overcome the aerodynamic resistance of each co-trailer unit in comparison with the head element. However, the airflow in every trailer-trailer gap has been not studied for articulated vehicles such as multilink highway trucks. This zone of the truck is characterized by a rather large length and height, and the condition of the air mass is influenced by airflow from the roof, side panels and area under the bottom of a truck links. A study of this task will help us to analyse aerodynamic losses mechanics in the trailer-trailer gap and to come to new effective and substantiated decision allowing power loss and thus fuel consumption reduction. The study lists the general calculation method evaluating the aerodynamic characteristics of the multilink truck on the base of numerical simulation of fluid dynamics using Flow Vision software. During calculation, there were determined speed distribution and power lines along the truck, the distribution of pressure on the truck surface, power and full drag coefficient. The results obtained allowed numerically evaluate the effect of the distance between the links on fuel consumption for multilink trucks and define the desired changes in their design.

3

Granice oporów ruchu w pojazdach : opór aerodynamiczny

Wrzecioniarz A., Ambroszko W., Pindel A.

Autobusy : technika, eksploatacja, systemy transportowe

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2018

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R. 19, nr 12

252--255

PL

W artykule omówione zostały granice oraz przykładowe metody minimalizacji oporu aerodynamicznego.

EN

In the paper limitations and exemplary methods of aerodynamic drag force minimization in different kinds of vehicles are described. Changes of value of aerodynamic drag coefficient during years are presented. Conclusions about future possible new solutions in different kinds of vehicles are formulated.

4

Investigation of fuel consumption of a passenger car depending on aerodynamic resistance and related aspects: a case study

Stopka O., Šarkan B., Vrabel J., Caban J.

Archiwum Motoryzacji

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2018

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Vol. 81, nr 3

111--118

EN

The research study investigates fuel consumption of a passenger car depending on aerodynamic resistance and related aspects. Introduction and next chapter describe all the resistance kinds affecting a passenger car while in-motion. Subsequent part outlines particular aspects such as aerodynamic resistance, aerodynamic resistance coefficient, car velocity and air temperature in terms of their effect on fuel consumption of selected passenger car. The most important chapter compares fuel consumption while a passenger car is in-motion on an expressway with closed and open windows with fuel consumption on a first class road infrastructure.

5

Wyznaczanie oporu właściwego i dyssypacji energii dla otworów wielkośrednicowych

Rosiek F., Sikora M., Urbański J.

Cuprum : czasopismo naukowo-techniczne górnictwa rud

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2017

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nr 3

5--11

PL

Do zbadania możliwości dostarczania powietrza do wyrobisk górniczych otworami wielkośrednicowymi konieczna jest znajomość ich oporów. W artykule, z uwagi na brak dotychczas doświadczeń i wyników badań krajowych na ten temat, zajęto się oporami aerodynamicznymi otworów wielkośrednicowych. Ten parametr ma istotne znaczenie dla wykorzystania tych otworów do prowadzenia powietrza do lub z wyrobisk dołowych.

EN

In order to investigate the possibility of fresh air delivery to mining excavations by means of large-diameter boreholes it is necessary to know the specific resistance of these excavations. Because no research results and no practical experiences of Polish mines in this regard are presented in the literature, the problem of aerodynamic resistance of large diameter boreholes is investigated in this paper. This parameter is crucial to determine the possibility of utilising this type of boreholes for fresh air delivery into underground excavations.

6

Koncepcja metody ograniczania strefy wirów za poruszającym się autobusem miejskim

Paszko M.

Autobusy : technika, eksploatacja, systemy transportowe

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2017

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R. 18, nr 6

1013--1015, CD

PL

Strefy wirów powodujące fluktuację ciśnienia na tylnej powierzchni poruszającego się pojazdu, stanowią jedną z głównych przyczyn oporu aerodynamicznego. W niniejszej pracy przedstawiono rozważania dotyczące możliwości zmniejszenia oporu aerodynamicznego autobusu miejskiego, poprzez wykorzystanie deflektorów powietrza w tylnej strefie nadwozia. W pracy przedstawiono również koncepcyjny model deflektora powietrza, dostosowanego do karoserii przykładowego współczesnego autobusu miejskiego.

EN

Swirl zones causing pressure fluctuations on the rear surface of a moving vehicle are one of the major causes of aerodynamic drag. In this paper, author presented the possibility of reducing the aerodynamic drag of a city bus by using air deflectors in the rear bodywork. The paper also presents a conceptual model of an air deflector adapted to the body-work of an exemplary contemporary city bus.

7

Analiza wpływu warunków atmosferycznych na opór aerodynamiczny autobusu miejskiego

Paszko M.

Autobusy : technika, eksploatacja, systemy transportowe

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2016

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R. 17, nr 12

1266--1268

PL

W niniejszym artykule przedstawiono analizę wpływu warunków atmosferycznych na poziom oporów aerodynamicznych autobusu miejskiego na przykładzie Mercedesa Conecto użytkowanego przez Miejskie Przedsiębiorstwo Komunikacyjne w Lublinie. Warunki brzegowe do obliczeń opracowano na podstawie danych z Krajowego Instytutu Meteorologii i Gospodarki Wodnej oraz serwisów pogodowych.

EN

This paper presents an analysis of the impact of weather conditions on the level of aerodynamic drag of a city bus on the example of Mercedes Conecto model exploited by the Municipal Transport Company in Lublin. The boundary conditions for the calculation were based on data from the Institute of Meteorology and Water Management and weather services.

8

Analiza struktur wirowych za poruszającym się autobusem miejskim i ich wpływu na opór aerodynamiczny. Cz. 2, Numeryczny model obliczeniowy

Paszko M.

Autobusy : technika, eksploatacja, systemy transportowe

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2016

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R. 17, nr 12

1262--1265

PL

W niniejszej pracy przedstawiono wyniki symulacji numerycznej, przeprowadzonej w celu wyznaczenia stosunku składowej siły oporu aerodynamicznego wynikającej ze spiętrzenia molekuł powietrza na czołowej części nadwozia do siły wynikającej z istnienia obszaru obniżonego ciśnienia w strefie bezpośrednio za poruszającym się autobusem miejskim. Analizę przeprowadzono dla typowych warunków użytkowych wykorzystując numeryczną mechanikę płynów.

EN

This paper presents results of the numerical analysis conducted to determinate the ratio of the aerodynamic drag component resulting from the zone of a low pressure in the area located directly behind the city bus model and drag component resulting from the pressure increase on the front surface of the vehicle. The analysis was conducted in CFD software for typical condition of use of a city bus.

9

Analiza struktur wirowych za poruszającym się autobusem miejskim i ich wpływu na opór aerodynamiczny. Cz. 1, Wprowadzenie w tematykę zagadnienia

Paszko M.

Autobusy : technika, eksploatacja, systemy transportowe

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2016

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R. 17, nr 12

1257--1261

PL

W niniejszym artykule przedstawiono wyniki analizy zjawiska obniżenia ciśnienia w śladzie aerodynamicznym za poruszającym się pojazdem oraz wpływu tego ciśnienia na opór aerodynamiczny. Praca stanowi wprowadzenie do analizy numerycznej przepływu powietrza w otoczeniu pojazdu, mającej na celu wyznaczenie stosunku siły oporu wynikającej ze strefy obniżonego ciśnienie w strefie za autobusem miejskim i siły oporu wynikającego z ciśnienia na powierzchni czołowej pojazdu.

EN

The paper presents the results of the analysis of the phenomenon of pressure decrease that takes place directly behind a moving vehicle and its impact on the aerodynamic drag. This work is an introduction to the numerical analysis aimed to determinate the ratio of drag force resulting from zone of low pressure in area directly behind the city bus and drag force resulting from pressure increase on the front surface of the vehicle.

10

Analytical determination of aerodynamic resistance of the skeletal telecommunication towers

Szafran J.

Structure and Environment

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2015

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Vol. 7, no. 1

5--14

EN

Computational determination of aerodynamic resistance for high truss structures like telecommunications towers is the subject of this study. Normalized procedures were presented with an example of an existing structure concerning the total wind coefficient. The results of calculations along with their broad elaboration and interpretation have been presented. Analyses and calculations were conducted for a tower of height equal to 84 metres and of a triangular cross section. The structure is characterized by round full rods as the legs of the tower and hot-rolled angle bars as the bracing. Two computational approaches were applied providing the results for each of them. The achieved results allow for stating that selection of a computational standard procedure should be adequate to an analysed structure and its characteristic features. The information included in the article is particularly useful in case of the determination of carrying capacity of existing tower structures on the basis of Eurocode standards.

11

Assessment of underpowered propulsion machinery in electrically driven small inland waterway passenger ships from classification society point of view

Dymarski C., Narewski M.

Journal of Polish CIMAC

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2014

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Vol. 9, no 1

7--16

EN

Paper presents short operational and engineering analysis of underpowered propulsion in small electrically propelled small inland passenger ships. There is evidence that in certain weather conditions the phenomena of added aerodynamic resistance of small water crafts may have serious influence on their speed and manoeuvrability. Existing regulations like class societies rules for ship classification and construction or EU Directive 2006/87/EC do not provide any requirements or guidelines on prediction of air or hydrodynamic resistance or propulsion power computations to be assessed by third party in design process. In the opinion of authors , the case is particularly important when electrical or hybrid propulsion is considered as prime mover. Existing knowledge allows for engine ering analysis to be conducted to provide better knowledge on the selection and construction of innovative propulsion machinery for ships where passengers safety is major factor of concern by wate rways administration, class societies and insurance institutions.

12

A concept of aerodynamically optimized electric car bodywork

Zuba M., Rząsiński R.

Selected Engineering Problems

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2013

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nr 4

163--168

EN

The article presents the process of selecting an optimal concept of an electric car bodywork according to the criterion of minimum aerodynamic drag. It also presents design and construction assumptions, the field of possible solutions and aerodynamic simulation results. Based on the performed analyzes, an optimal design solution was selected and graphical results of simulations for the best solution were presented.

13

Jednostkowy opór aerodynamiczny lutniociągów zbudowanych z lutni elastycznych

Knechtel J.

Mechanizacja i Automatyzacja Górnictwa

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2011

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R. 49, nr 2

18-27

PL

Wykonano badania, których celem było wyznaczenie wartości jednostkowego oporu aerodynamicznego lutniociągu zbudowanego z lutni elastycznych. Badano lutnie elastyczne niezbrojone (do wentylacji tłoczącej) oraz lutnie zbrojone (do wentylacji ssącej). Pomiary parametrów wentylacyjnych wykonano zarówno na powierzchni (u producentów lutni) jak i w czynnych wyrobiskach górniczych (na dole kopalni). Na podstawie uzyskanych wyników zaproponowano wartości jednostkowego oporu aerodynamicznego, jakie powinni zapewnić producenci lutni elastycznych.

EN

The tests were conducted to determine the value of aerodynamic resistance of an air duct made of flexible air pipes. The tested air pipes were non-armoured flexible air pipes (for forced ventilation) and armoured air pipes (for suction ventilation). The measurements of ventilation parameters were carried out both on the surface (at the producers of air pipes) and in the working excavations under the ground. On the basis of the obtained results, the author proposed the values of aerodynamic resistance to be followed by the producers of flexible air pipes.

14

Korygowanie współczynników oporu oraz oporów aerodynamicznych bocznic sieci wentylacyjnej

Madeja-Strumińska B.

Cuprum : czasopismo naukowo-techniczne górnictwa rud

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2004

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nr 2

39-50

PL

W artykule przedstawiono propozycję metody korygowania przybliżonych wartości współczynników oporu oraz oporów właściwych wyrobisk górniczych przyjmowanych do obliczeń wentylacyjnych na podstawie katalogów, poradników lub norm. Sposób ten oparty jest m.in. o znajomość parametrów geometrycznych wyrobisk, strumieni objętości powietrza w tych wyrobiskach i podstawowe prawo dotyczące oczek sieci wentylacyjnej.

EN

The paper includes proposal of the method correcting the approximate values of the drag coefficients and specific resistance of the mine workings used in the ventilation calculation, handbooks and standards. The method is based, among others, on geometry of the mine workings, air streams in the workings and basic Iow concerning ten ventilation network net mesh.

15

Źródła niepewności w kopalnianych pomiarach wentylacyjnych

Krach A.

Archives of Mining Sciences

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2004

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Vol. 49, nr spec

151-178

PL

W artykule przedstawiono sposoby określania niepewności pomiaru wybranych parametrów wentylacyjnych, mierzonych w ramach ciągłego monitoringu lub okresowych kontroli procesu wentylacji kopalni. W kolejnych rozdziałach artykułu zaprezentowano funkcje modelujące pomiar i wariancje złożone następujących wielkości: -średnia prędkość i strumień objętości powietrza w wyrobisku; -stężenie niebezpiecznych gazów w strumieniu powietrza; -absolutne ciśnienia statyczne w węzłach sieci wentylacyjnej, różnice ciśnień statycznych i całkowitych, straty naporu; -gęstość powietrza w bocznicach, niezbędna przy pomiarach prędkości powietrza przyrządami spiętrzającymi, przy wyznaczaniu oporów aerodynamicznych, depresji naturalnej i sporządzaniu schematów potencjalnych; -opory aerodynamiczne wyrobisk, od których zależy rozpływ powietrza w sieci wentylacyjnej.

EN

Monitoring and control of ventilation in mines requires the measurements of basic parameters on the regular or periodic basis. The main parameters of the ventilation process include: -average velocity and stream of air in the mine headings; -concentration of hazardous gases in the air stream; -absolute static pressure in the nodes of the ventilation network, differences in absolute and total pressure, pressure loss; -air density in branches required in airflow velocity measurements using impact devices, necessary to determine aerodynamic drag, natural depression and to graph potential diagrams; -aerodynamic resistance in mine headings which affects air propagation in the ventilation network. Of particular interest is reliability of measurements. In accordance with the guidelines issued by the International Committee of Measures, the quality of measurement is measured by its uncertainty. The standard value of uncertainty of measurements is expressed as the standard deviation. When the measurement result is derived from other quantities, the total uncertainty equals the positive square root of the complex variation, expressed by the formula (1). A major determinant of measurement result precision in complex measurements is the function modelling the measurements. It should involve as many correlations between input quantities as possible, even though some of these quantities are negligible while computing the final results. Further sections outline the methods of estimating the uncertainty of measurements of selected ventilation parameters. Chapter 4 reviews the major sources of uncertainty of measurements of the average airflow velocity in the gallery cross-section, using a vane anemometer. The method of continuous traversing is employed. The modelling function is provided (3) and so is the complex variance of the measurement result (4). Component variations of the two input parameters in the model are: -accuracy of readouts of average airflow velocity from the anemometer; -coefficients of the anemometer characteristics; -fluctuations of airflow velocity; -shape of the traversing path; -the rate of anemometer movement; -velocity profile in the gallery cross-section; -presence of people in the gallery cross-section. Chapter 5 investigates the uncertainty of measurements of the surface area of the gallery cross-section, which comprises the uncertainty of air volume measurements expressed by (20) in chapter 6. Chapter 7 focuses on measurements of local concentrations of hazardous gases and volume fractions of those gases in the stream of flowing air. Variances of streams of hazardous gases in measurements using the summation of elementary streams or measurements of local flow intensity are given as (22) and (25). Measurements of pressure and pressure differences are of key importance in mines. They are required for flow velocity measurements using impact devices, in measurements of pressure loss, fan characteristics, aerodynamic drags and while preparing socalled depression images of the mine. Measurements of pressure differences at two distant points of the ventilation network are taken using the barometric method whereby the difference between absolute pressures at those points is measured. Chapter 8 deals with uncertainty involved in measurements of barometric pressure and pressure difference, taking into account such sources of uncertainty as random fluctuations of absolute pressure in the mine headings, characteristics of the measuring equipment and resolution of the readout systems. In the case of measurements of pressure differences three cases are considered: -uncertainty of the difference of two absolute pressures measured at the beginning and at the end of the gallery with two different instruments, the pressure measurements taken at certain .time intervals (39); -uncertainty of the difference of two absolute pressures measured at the beginning and at the end of the gallery using the same instrument, the pressure measurements taken at certain time intervals; -uncertainty of the difference of two absolute pressures measured at the beginning and at the end of the gallery with two different instruments, the pressure measurements taken at the same time (43). The knowledge of air density is requisite for measurements of airflow velocity using impact devices, for determining aerodynamic resistance, natural depressions and potential diagrams. Uncertainty involved in air density measurements is investigated in chapter 9. Results of measurements of absolute pressure difference, air density, airflow velocity and gallery cross-section and the difference in altitude of control points are input values to the mathematical model of measurements of aerodynamic resistance, expressed as (59) or (60). The uncertainty of resistance measurement is the complex one. Individual components of the complex variance of the drag are investigated in chapter 10. For each input value the sensitivity factor is also provided.

16

Opory tam wentylacyjnych w kopalniach LGOM.

Rosiek F., Sikora M., Urbański J.

Rudy i Metale Nieżelazne

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1998

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R. 43, nr 3

109-116

PL

Dla kopalń LGOM przeprowadzono pomiary szczelności najczęściej stosowanych tam wentylacyjnych. Wykazały one, że szczelności tam są dużo niższe niż szczelności tych samych typów tam przytaczane w literaturze. Dla praktycznego wykorzystania wyników badań szczelności tam wentylacyjnych opracowano dla wybranych typów tam klasyfikacje oparte na ich oporze aerodynamicznym. Przy opracowywaniu klasyfikacji oparto się głównie na wielkości strat powietrza występujących w poszczególnych rodzajach tam. Opracowane klasyfikacje pozwalają dobierać w trakcie prowadzenia badań symulacyjnych rozpływu powietrza w sieciach wentylacyjnych kopalń LGOM opory tam wentylacyjnych zależnie od warunków geologiczno-górniczych i wymaganej ich szczelności.

EN

Aerodynamic tightness of the ventilation doors, most often used in LGOM mines, has been measured. The results of measurement are much lower then the numbers given in the literature for the same types of ventilation doors. Classifications based on aerodynamic resistance have been created for chosen types of ventilation doors. Those classifications have been derived from the values of air-loss measured in different types of ventilation doors. The presented classifications enable choice of aerodynamic resistances of the ventilation doors for the purpose of airflow simulation, depending on geological and mining conditions in the headings and on the required leak resistances of the doors.