Temat: coefficient - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Application of GPS receiver to road tests of automobile
Autorzy:: Sar, H.
Pokorski, J.
Fundowicz, P.
Reński, A.
Powiązania:: https://bibliotekanauki.pl/articles/242475.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: automobile dynamics
air drag coefficient
rolling drag coefficient
ECE 13 Regulation
road transport
Opis:: The article presents the assessment of the possibilities of applying GPS receiver for the measurement and acquisition of the longitudinal velocity of automobile in the investigations of longitudinal dynamics of automobile. For many years for the measurement of the longitudinal velocity Correvit-L sensors are applied. Major simplification of the measurement of the velocity with the GPS receiver, compared with correlational-optical sensors Correvit-L is giving the possibility to faster prepare the automobile for examinations. The more so as only recently GPS receivers with 10 Hz sampling rate are available. In the paper is shortly described the software specially designed for the measurements that makes it possible to simultaneously measure both the longitudinal velocity signal from GPS receiver and from Correvit-L sensor in real time. Furthermore, the application of the measurement of the velocity is presented on the basis of such road tests as the attempt of accelerating through the following gears, the attempt of free deceleration and the attempt of braking according to ECE 13 Regulation. On the basis of the mentioned manoeuvers the characteristics of the vehicle’s acceleration and dynamic coefficient, rolling and air drag coefficient and the braking deceleration were determined. The paper shows also some problems connected with applying GPS receiver to measure longitudinal velocity of the automobile.
Źródło:: Journal of KONES; 2013, 20, 3; 359-366
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Estimating the main dimensions of the ship’s hull
Autorzy:: Charchalis, A.
Powiązania:: https://bibliotekanauki.pl/articles/247088.pdf
Data publikacji:: 2018
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: seagoing ships
hull coefficient
hull dimensions parameters
Opis:: Preliminary ship owner's assumptions for new ship consist of deadweight, speed-shipping line and others. Taking it as a base, in early stage of design one has to select propulsion type. This goal needs definition of principal dimensions of a vessel, which are the base for further calculations of hull’s resistance and evaluation of necessary power of main engine to fulfil shipping requirements. Selection of main dimensions of vessel is limited by rules regarding buoyancy, stability, hull strength, manoeuvring capability, and limitations related to seaways or harbours characteristic. In this article is presented the methodology of calculation of principal parameters of a vessel, necessary for calculation of displacement in relation to vessel’s type, volumetric coefficients, Froude number, and others values affecting ship’s dimensions. It is about midship section coefficient, waterline coefficient, prismatic coefficient. Those values are necessary for calculation of hull resistance. In the article, are presented major constraints for designing of new vessels coming from ship-owner assumptions such as seafaring limitations. In the table is presented comparison of results of calculations above-mentioned values of three type of vessels representing same displacement. There are also presented different calculation methods of transverse midship section coefficient and wet area coefficient, for 3 types of vessels (container vessel, bulk carrier and tanker with displacement of 120000 t.
Źródło:: Journal of KONES; 2018, 25, 2; 75-80
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Friction coefficient determination based on the results of ball – on - flat test
Autorzy:: Szymczyk, E.
Jachimowicz, J.
Prasek, Ł.
Powiązania:: https://bibliotekanauki.pl/articles/248003.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: friction coefficient
ball-on-flat test
FFT
Opis:: The interaction of contacting surfaces in relative motion is basic for every engineering design. The transmission of load from one rubbing surface to its mating surface under conditions of dry contact is taken into account. Microlocal or global models of friction are used to describe this phenomenon. In global approach, frictional force is proportional to normal load. A coefficient of external friction depends on the type, shape, and precision of finishing the surfaces of mating elements. The aim of the paper is analysis of a friction coefficient for 2024T3 aluminium alloy during cyclic tangential loading. Experimental tests are carried out on a ball-on-flat wear-testing machine Ducom. Tests of reciprocating friction are carried out using the following friction pairs of specimens: the ball specimen is made of high strength aluminium alloy PA25 and the plane specimen is made of 2024T3 alloy. Finally, graphs of temporary friction coefficients versus time in the form of fluctuated periodical functions are obtained. Two phases of friction are detected. However, during the first stage, the friction coefficient is relatively small while in the second period it rapidly increases and tends to become more irregular. Static and dynamic friction coefficients are estimated. In order to determine the dynamic coefficient the Discrete Fourier Transformation is used. The calculation of the dominant amplitude (corresponding to test frequency) of the studied functions is possible due to this method. An increase of the friction coefficient with an increase of normal load is observed. A cladding layer also causes an increase of friction, especially in the second phase.
Źródło:: Journal of KONES; 2012, 19, 1; 415-422
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Influence of the ballistic protection on aerodynamic helicopter characteristics
Autorzy:: Wisniewski, A.
Wisniowski, W.
Powiązania:: https://bibliotekanauki.pl/articles/244913.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: passive ballistic protection
aerodynamic coefficient
stabiliser
helicopter fuselage
Opis:: This paper contains results of experimental tests of the influence of passive ballistic protection on aerodynamic coefficients of the model fuselage of the Sokol helicopter. The research was carried out in the Institute of Aviation low speed wind tunnel T3 of 5 m diameter on the helicopter test stand. Measurements of aerodynamic coefficients acting on the fuselage with and without passive ballistic protection were taken using six–component internal strain gauge balance placed inside the model of the fuselage for the angles of attack α = –90-90° with step 10° and for sideslip angles β = –10°, 0°, 10°. Several aerodynamics coefficients: drag (Cx), force (Cy), lift (Cz) and moment: bank (Cmx), pitch (Cmy) and yaw (Cmz) were analysed. The results of the wind tunnel tests were presented in figures as non-dimensional mean values of the above aerodynamic coefficients. Different measurements of aerodynamic characteristics were made like: the influence of Reynolds number on the Cx of the helicopter fuselage with and without protection and the comparison of aerodynamic characteristics of the helicopter fuselage Cx, Cy, Cz, Cmx, Cmy, Cmz as the function of α, without stabiliser, with and without protection. Moreover, a comparison Cx, Cy, Cz, Cmx, Cmy, Cmz as the function of α, with a stabiliser, with and without protection was made and a comparison of the influence of a stabiliser and protection on the above aerodynamic characteristics for the range of useful angles of attack were analysed. A comparison of the influence of a stabiliser and protection on aerodynamic characteristics of the helicopter fuselage Cx, Cy, Cz, Cmx, Cmy, Cmz for the range of α angles of attack was also described.
Źródło:: Journal of KONES; 2016, 23, 4; 549-554
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Possibilities of graphical environment application for determining parameters of the mechanical system
Autorzy:: Jaśkiewicz, M.
Ludwinek, K.
Staszak, J.
Suliga, T.
Powiązania:: https://bibliotekanauki.pl/articles/247237.pdf
Data publikacji:: 2011
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: mechanical system parameters
stiffness coefficient
damping
graphical environment
Opis:: The article discusses the possibility of using LabView graphical environment for visualization and quick and easy identification of parameters of the dynamic system. For further analysis a human driver model, sitting in a car seat, fastened with seatbelts is used. This model consists of eight rigid solids. The solids reflect parts of the human body. In the model head and neck are separate segments. The torso is divided into three parts: upper torso, middle torso and lower torso. In this model also a leg is a separate segment. The leg is divided into three parts: thigh, lower leg and foot. The individual solids are connected by torsionally vulnerable joints. Additionally a seat back was modelled too, which limits the movement of three segments of the torso. Similarly as in the standard car with the seat equipped with a three-point safety belt, in the model presented in this article, the location of the upper and lower seat belt was modelled and shown. The whole model has two frames of reference. For this purpose, a graphical language program was developed, in which by changing the settings of analogue units representing parameters such as mass ratios, stiffness, damping, moments of inertia, it is possible to determine the impact of these parameters on the delay shapes, speed, energy, etc.
Źródło:: Journal of KONES; 2011, 18, 4; 151-164
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: The heat transfer coefficient calculation in the ice cylinder based on in-cylinder pressure data
Autorzy:: Przybyła, G.
Postrzednik, S.
Żmudka, Z.
Powiązania:: https://bibliotekanauki.pl/articles/247975.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: heat transfer coefficient
combustion engines
in-cylinder pressure
Opis:: In this paper the calculations algorithm of heat-transfer coefficient in the combustion chamber of the internal combustion engine is presented. Developed algorithm is based on the in cylinder pressure data. The proposed algorithm can be helpful to determine the average values of heat-transfer coefficient from working medium to the combustion chamber walls (crown of a cylinder head, cylinder walls and piston head) during combustion process. The calculation method includes modified one zone heat release model in combustion chamber of SI engine. Proposed method consists in closing the energy balance equation by the coefficient which expresses the heat losses to the walls of the combustion chamber. The average value of the heat losses during combustion process is calculated by two steps. Firstly, the integration of the energy balance equation (without specifying the heat losses) leads to designation of the so-called net value of heat released in cylinder. In the next step the amount of the total energy supplied to the cylinder is determined taking into account the chemical energy of the supplied fuel. The difference between the supplied value of chemical energy and heat released net value allows to determine the heat losses average value. In last stage, the heat flow equation leads to calculate the mean value of heat transfer coefficient during combustion process.
Źródło:: Journal of KONES; 2013, 20, 4; 382-388
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Impact of magnetic particles concentration in ferrooil on its magnetic susceptibility coefficient χ
Autorzy:: Frycz, M.
Anioł, A.
Powiązania:: https://bibliotekanauki.pl/articles/241625.pdf
Data publikacji:: 2014
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: ferro-oil
magnetic particles concentration
magnetic susceptibility coefficient
Opis:: The purpose of this article is to determine the effect of the concentration of magnetic particles in ferro-oil on the value of its magnetic susceptibility coefficient χ. Determination of the flow and operating parameters of slide journal bearings lubricated with ferro-oils requires, inter alia, designation the first magnetization N and the magnetic induction B vector components, dependent on the magnetic propertis of the lubricant. The fundamental problem lies in the inability to make direct accurate measurement of magnetic induction in the lubricating gap of slide bearing and its solution is to determine it on the analytical and numerical way. A key issue for the accuracy of such solutions is to obtain reasonably accurate values of magnetic susceptibility χ. This article attempts to determine these values and estimate their relationship with the concentration of magnetic particles concentration in ferro-oil being potential lubricant above-mentioned bearings. In this paper, the authors present the characteristic of experimental test benches to determine the coefficients of the magnetic susceptibility. They present method of determining this value from obtained measurement data and analyse the impact of the magnetic particles concentration in ferro-oil on its magnetic susceptibility values. Tests were performed for selected concentrations of magnetic particles in ferro-oil ranging: 2%, 4%, 6% and 8% and the tested ferro-oil was product from Unterensingen FerroTec Company (Germany) which is a mixture of colloidal mineral engine oil LongLife Gold Penzzoil class SAE 15W-40 with addition of Fe3O4 magnetic particles and a surfactant.
Źródło:: Journal of KONES; 2014, 21, 4; 111-117
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Designing constraints in evaluation of ship propulsion power
Autorzy:: Charchalis, A.
Powiązania:: https://bibliotekanauki.pl/articles/244237.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: seagoing ships
hull coefficient
hull dimensions parameters
propulsion power
Opis:: Preliminary ship owners' assumptions for new ship consist of deadweight (for container vessel load capacity TEU), speed shipping line and others. Taking it as a base, in early stage of design one has to select propulsion type. This goal needs definition of principal dimensions of a vessel, which are the base for further calculations of hull’s resistance and evaluation of necessary power of main engine (engines) to fulfil shipping requirements. Selection of main dimensions of vessel is limited by rules regarding buoyancy, stability, hull strength, manoeuvring capability, and limitations related to seaways or harbours characteristic. In this paper is presented the methodology of calculation of principal parameters of a vessel, necessary for calculation of displacement in relation to vessel’s type, volumetric coefficients, Froude number, and others values affecting ship’s dimensions. It is about midship section coefficient, waterline coefficient, prismatic coefficients and hull feature and area coefficients. Those values are necessary for calculation of hull resistance. In the table are presented comparison of results of calculations above mentioned values and movement resistance and propulsion power of three container vessels representing different load capacity and one bulk carrier. There are also presented different calculation methods of transverse midship section coefficient and wet area coefficient, for 5000TEU container vessel.
Źródło:: Journal of KONES; 2013, 20, 1; 29-34
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Prediction of the natural frequency of ship’s roll with regard to various models of roll damping
Autorzy:: Krata, P.
Wawrzyński, W.
Powiązania:: https://bibliotekanauki.pl/articles/244403.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: sea transport
ship stability
ship rolling
roll damping coefficient
Opis:: One of the most important dynamic phenomenon recognized as dangerous to seagoing ships is the resonance gain of rolling. This may occur due to nonlinearity of ship response in resonance conditions, i.e. when the encounter wave frequency is similar to the natural frequency of ship roll motion. Such coincidence should be avoided therefore shipmaster steers clear of some configurations of speed and course resulting in potential synchronous rolling. Nowadays, according to the IMO Intact Stability Code the natural period of roll is determined with the use of very simplified GM-based formula. The paper deals with the problem of more sophisticated prediction of ship’s natural rolling frequency with the use of the one degree-of-freedom roll equation with regard to nonlinear restoring moment. A special emphasis is put on the damping coefficient modelling which remains one of the crucial issues in terms of rolling simulation. Two typical approaches to the damping coefficient estimation are tested, the linear and the nonlinear one according to Ikead’s method. The set of ship roll simulations is carried out for a wide range of excitation frequency and a variety of exciting moment. The results of computation focused on the natural frequency of ship roll prediction are compared to assess the influence of damping model selection.
Źródło:: Journal of KONES; 2016, 23, 3; 289-296
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Coefficient of thermal expansion as a component quality estimation of alloys on pistons of combustion engines
Autorzy:: Sieminska, B.
Powiązania:: https://bibliotekanauki.pl/articles/245892.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: combustion engines
engine pistons
thermal expansion
coefficient of thermal expansion
Opis:: The aim of realized works in the area of materials on pistons is: low thermal expansion, small differences of coefficient of thermal expansion between heating and cooling, high stiffness at elevated temperatures, high hardness and wear resistance. Changes in thermal expansion coefficient during heating and cooling may be very large, as well as during subsequent cycles of heating and cooling of an internal combustion engine pis ton with respect to standard silumin alloys usedfor pistons of internal combustion engines. The paper presents: coefficient of linear expansion a for the AlSi standard alloy, coefficient of linear expansion a for the AlSi alloy with the apositive differences between cooling and heating, coefficient of linear expansion a for the AlSi alloy with the a negative differences between cooling and heating, coefficient of linear expansion a for the AlSi alloy with the apositive and negative differences between cooling and heating, coefficient of linear expansion a for the AlSi alloy with the apositive, negative and positive differences between cooling and heating, coefficient of linear expansion a for the AlSi alloy with the very small a differences between cooling and heating, coefficient relative elongation as afunction of temperature with the positive elongation differences between cooling and heating, coefficient relative elongation with the very small elongation differences between cooling and heating, coefficient the course of derivative as a function of temperature (T) during heating and cooling with the positive elongation differences.
Źródło:: Journal of KONES; 2009, 16, 4; 575-583
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:: The effect of Pt internal catalyst on relative carcinogenic coefficient (RCC) of polycyclic aromatic hydrocarbons (PAHs) emitted from diesel engine
Autorzy:: Janicka, A.
Walkowiak, W.
Szczepaniak, W.
Powiązania:: https://bibliotekanauki.pl/articles/247594.pdf
Data publikacji:: 2008
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: internal catalyst
polycyclic aromatic hydrocarbons
relative carcinogenic coefficient
diesel engine
Opis:: One of the main anthropogenic sources of PAHs emission is motorization, especially compression ignition engines. The researches of International Agency for Research on Cancer (IARC) proved that some compounds from polycyclic aromatic hydrocarbons group are toxic for live organisms and cause damages of adrenal glands, lymphatic, circulation and respiratory systems. Because of carcinogenic properties and common occurrence in human environment benzo(a)pirene has been accepted as polycyclic aromatic hydrocarbons indicator. In relation to benzo(a)pirene, Nisbet and LaGoy determined relative carcinogenic coefficients (RCC) for individual polycyclic aromatic hydrocarbons. The paper presents results of analysis of PAHs RCC emitted from SB3.1 self-ignition engine with Pt active coating application inside. The catalyst was applied on engine valves surface. Zirconium ceramic was chosen as a coating for catalyst application (also because of its thermo-isolating properties). Because of unstable parameters of self-ignition engine work (pressure and temperature jumps), PAHs were extracted from two phases: gas phase and solid phase (particle matter - PM). A chromatographic method of polycyclic aromatic hydrocarbons identification and analysis, because of their low level of concentration in exhaust gases, needed to be supported by sample purification and enrichment stages. It has been found that implementation of catalytic coating on valves of the engine causes decrease of polycyclic aromatic hydrocarbons concentration in exhaust gases, what results in decrease (in most cases) of the sum of relative carcinogenic coefficient of polycyclic aromatic hydrocarbons.
Źródło:: Journal of KONES; 2008, 15, 3; 209-213
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 12.

Tytuł:: The friction force and friction coefficient in the journal sliding bearing ferrofluid lubricated with different concentrations of magnetic particles
Autorzy:: Frycz, M.
Miszczak, A.
Powiązania:: https://bibliotekanauki.pl/articles/247265.pdf
Data publikacji:: 2011
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: hydrodynamic pressure
capacity
friction force
friction coefficient
ferrofluid
numeric calculation
Opis:: There is an important operational parameter in the case of sliding bearings are friction forces and coefficient of friction. It depends on how much proportions of heat in the gap of the oil film from the value of the friction force. Ferrofluid lubricated sliding bearings have specific structure and are suitable only for use in specific cases. We may use them in the absence of gravity, vacuum, or in case of strong magnetic fields or radioactive. Maintenance of lubricant in the oil-gap as well as the viscosity change occurs through controlling of the external magnetic field. Change of the value of viscosity and mass forces (magnetic forces) in the equation of momentum depends on the concentration of magnetic particles and the intensity of external magnetic field. The aim of this paper is to present the influence of concentration of magnetic particles on the friction force value and coefficient of friction. The numerical calculations of friction forces and friction coefficient have been performed before setting the hydrodynamic pressure and a lift force from the Reynolds-type equation. Reynolds-type equation has been derived from basic equations, ie equations of momentum and equations of stream's continuity. There have been also used Maxwell's equations for the ferrofluid in the case of stationary magnetic field's existence. It has been assumed stationary and laminar flow of lubricant liquid and the isothermal model for lubrication of slide bearings. As the constitutive equation has been used Rivlin-Ericksen one. The cylindrical journal bearing of finite length with the smooth sleeve of whole angle of a belt has been taken into consideration. In a thin layer of oil film has been assumed constancy of the oil density with temperature changes and the independence of the oil's thermal conductivity coefficient from thermal changes. The viscosity of the oil depends mainly on the magnetic field.
Źródło:: Journal of KONES; 2011, 18, 4; 113-120
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:: Light absorption spectra for lubricate oil quality tracking in the combustion engine
Autorzy:: Baszanowska, E.
Otremba, Z.
Powiązania:: https://bibliotekanauki.pl/articles/243648.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: lubricate oil
dissolved oil
absorption spectroscopy
absorption coefficient
engine system
Opis:: The important role in the proper functioning of combustion engines plays the quality of lubricates oil. However, the quality of oil changes with the time of exploitation. Therefore, several parameters for examination of oil quality were determined; however, the indicator for quick and efficient tracking of evolution of oil with exploitation time is still searched. Taking into account the complex composition of oils, the ability of oils components to absorb light in various wavelengths is considered. In the article absorption properties of oils is discussed in relation to the time of circulation of oil in the engine lubricate system. For this study, two lubricate oils designated to lubricate the cylinder of vessel engines with different brightness and transparency were used. Oil samples were dissolved in organic solvent –n-hexane and several oil concentration were prepared based on dilution method. Absorbance spectra for eachsamples of oil were registered in the range of wavelength 240-600 nm. Obtained results indicate the changes of value of absorbance in relation to the kind of oil; however, the shape of absorbance spectra is independent from the kind of oil. For studied kinds of oil, characteristic peak independent from the kind of oil located at 260 nm was determined. Based on Lambert-Beer law absorption coefficient was identified as a potential indicator to oil quality evaluation with the time of exploitation in the engine system. Preliminary test for two fresh lubricate oils allow to conclude that absorption coefficient for selected wavelength located at 260 nm could be a sensitive parameter for quick estimating the degree of deterioration of the oil in engine system.
Źródło:: Journal of KONES; 2016, 23, 1; 55-60
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 14.

Tytuł:: Influence of cooling air mass flux variation on the convective heat transfer coefficient of HPT rotor disk
Autorzy:: Domański, R.
Jedliński, K.
Powiązania:: https://bibliotekanauki.pl/articles/243193.pdf
Data publikacji:: 2007
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: CFD
Fluent
High Pressure Turbine
Rotor Disk
convective heat transfer coefficient
Opis:: The paper is focused on the convective heat transfer phenomena on the High Pressure Turbine (HPT) rotor disk wall. The disk is a part of PW6000 turbojet engine (designed by Pratt & Whitney Company) and is a base of the 1st stage of HPT blades having very high temperature (combustion gases leaving combustion chamber have temperature around 1800 K). The analyzed disk is cooled by the air taken from one of the compressor's stages. The air gets to the gap between HPT disk and mini disk through discrete pump holes and then divides into two streams. One of them is used to decrease temperature of turbine blades and the second one is directed to the sequent turbine stages. Numerical analysis (made in Fluent) is based on the two dimensional aerodynamic model (in steady state) which is the cross section of the real geometry. There are three different sets of boundary conditions analyzed. Each of them has the same flow splits (40% of air is used to cool turbine blades and 60% gets to the next turbine stage) and all settings except cooling air mass flow on the inlet. Convective heat transfer coefficients are calculated using different method then proposed by Fluent (WFHTC and SHTC options give wrong results in this case). Coefficients are presented along disk wall and are compared with Fluent calculation methods.
Źródło:: Journal of KONES; 2007, 14, 2; 107-114
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 15.

Tytuł:: Influence of hardness on mechanical properties of elastomers
Autorzy:: Ochelski, S.
Bogusz, P.
Kiczko, A.
Powiązania:: https://bibliotekanauki.pl/articles/246003.pdf
Data publikacji:: 2010
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: experimental research
elastomers
mechanical properties
relative damping coefficient
mechanical loss angle
Opis:: In this paper, elastomers with different hardness factors were examined to evaluate the influence of the hardness on their mechanical properties. The following hardness numbers, measured in Shore A hardness scale, were investigated: 40; 60; 70 and 90°. Basic mechanical tests i.e. axial tension and axial compression have been performed in order to calculate elastic properties and stress values corresponding to the fixed strains: epsilon = 0.2; 0.3 and 0.5. The sigma (epsilon) dependences from the tension and compression tests are nonlinear and have different shapes. The tension plot can be described by a convex parabola, while the compression curve can be approximated by a concave one. dynamic load tests with loading freąuencies 0.01; 0.1; 1.0 and 3,OHz were performed in order to determine the hysteresis loop and to obtain force and displacement dependences in time. From those results the following factors were calculated: relative damping coefficient and mechanical loss angle, as well as their dependence on load frequencies. The influence of hardness on both in-phase and out-of-phase components of normal modulus were investigated. The sensitivity of the examined elastomers to the loading rate was also investigated.
Źródło:: Journal of KONES; 2010, 17, 1; 317-325
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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