Wyniki wyszukiwania - BazTech

1

Thermodynamic modeling of combustion process of the internal combustion engines - an overview

Stepanenko Denys, Kneba Zbigniew

Combustion Engines

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2019

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R. 58, nr 3

27--37

EN

The mathematical description of combustion process in the internal combustion engines is a very difficult task, due to the variety of phenomena that occurring in the engine from the moment when the fuel-air mixture ignites up to the moment when intake and exhaust valves beginning open. Modeling of the combustion process plays an important role in the engine simulation, which allows to predict incylinder pressure during the combustion, engine performance and environmental impact with high accuracy. The toxic emissions, which appears as a result of fuels combustion, are one of the main environmental problem and as a result the air pollutant regulations are increasingly stringent, what makes the investigation of the combustion process to be a relevant task.

2

Comparison of methods for determining the convective heat transfer coefficient for the induction-heated charge

Kurek A., Golak S., Przyłucki R., Kachel A., Smalcerz A., Ślęzok M.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 2b

266-269

EN

This paper presents a comparison of convective heat transfer coefficients determined by use of different methods. The coefficients were estimated from dimensionless numbers (5 variants) and by numerical fluid dynamics simulation (4 variants). A computer simulation of induction heating process of a steel non-magnetic workpiece in a vertical induction heater was adopted as a calculation model. Except for the value of convective heat transfer coefficient also the influence of its changes on temperature distribution in the heated workpiece was monitored.

PL

W pracy porównano wartości współczynników konwekcyjnej wymiany ciepła wyznaczonych różnymi metodami. Współczynniki wyznaczono w oparciu o liczby kryterialne (5 wariantów) i bazując na symulacji numerycznej mechaniki płynów (4 warianty).Oprócz wartości współczynnika wymiany ciepła przez konwekcję kontrolowano także wpływ zmiany tego współczynnika na rozkład temperatury w nagrzewanym wsadzie.

3

Determination of Natural Convective Heat Transfer Coefficient for Plain Knitted Fabric via CFD Modeling

Duru Cimilli S., Deniz E., Candan C., Nergis B. U.

Fibres & Textiles in Eastern Europe

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2012

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Vol. 20, no. 1 (90)

42-46

EN

In this study, the natural convective heat transfer coefficient for plain knitted fabric is estimated by numerical modeling, and the applicability of commercial software using the finite volume method (FVM) to textile problems was investigated. For this purpose, the convective heat transfer coefficient of plain knitted fabric made from cotton was first measured experimentally with the help of the in-house set-up developed. Then a plain weft knitted fabric model was created using CATIA, and Gambit and Fluent software was employed for numerical analyses. Finally experimental results were compared with those obtained from the numerical method. Based on the results, it was concluded that the numerical modeling simulated the related experimental study well. It was also stated that the numerical model developed has the potential to obtain the heat convection coefficient of the material considered for different conditions such as environment temperature etc.

PL

Dla możliwości analizy stosowanego systemu obliczeń wykonano wstępnie pomiary współczynnika konwekcji naturalnej dla dzianin bawełnianych o splocie płaskim za pomocą układu zaprojektowanego przez autorów. Następnie zaprojektowano model dzianiny i zastosowano programy komputerowe do przeprowadzenia obliczeń. Dzięki porównaniu wyników uzyskanych z doświadczeń i obliczeń stwierdzono, że obliczenia wiernie odzwierciedlają warunki rzeczywiste. Stwierdzono jednocześnie, że opracowany model pozwala na uzyskiwanie dobrych wyników przy rożnych warunkach zewnętrznych takich jak np. temperatura otoczenia.

4

Influence of cooling air mass flux variation on the convective heat transfer coefficient of HPT rotor disk

Domański R., Jedliński K.

Journal of KONES

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2007

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Vol. 14, No. 2

107-114

EN

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.

5

Projekt doświadczalno-teoretycznych badań termodynamicznych własności materiałów panewek poprzecznych łożysk ślizgowych

Wierzcholski K., Miszczak A.

Tribologia

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2001

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nr 2

201-210

PL

W niniejszej pracy autorzy przedstawiają projekt badań własności materiałów panewek poprzecznych łożysk ślizgowych stacjonarnie obciążonych w warunkach zbliżonych do rzeczywistych warunków pracy węzła tarcia. Badania te będą polegały na analityczno-numerycznym wyznaczeniu rozkładów temperatury, deformacji szczeliny smarnej i deformacji panewki w procesie iteracyjnym aż do uzyskania zbieżności wyników. Wtedy dopiero wyznacza się ostateczne parametry eksploatacyjne łożyska ślizgowego w postaci: siły nośnej, siły tarcia, współczynnika tarcia a w efekcie końcowym uzyskuje się opis termodynamicznych właściwości materiałów łożyskowych panewki w trakcie eksploatacji.

EN

In this project we demonstrate solutions in the field of the conjunction of three problems. We solve in tribology the problem of thermoelasticity, problem of hydrodynamic lubrication and problem of electromagnetic fields. We show in this project the complex solutions of strain and stress for electromagnetic fields occurring in thin elastic layer of bearing alloy and thin layer of lubricant in slide bearing gap. We find the temperature distributions in elastic layer of bearing alloy and in the lubricant taking into account the complex boundary conditions. We find deformations of elastic layer of bearing sleeve on the basic of fluid mechanic and theory of elasticity.