Wyniki wyszukiwania - BazTech

1

Analysis of heat transfer in a supersonic rocket head

Rosłowicz A., Bednarczyk P.

Prace Instytutu Lotnictwa

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2017

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Nr 1 (246)

79--94

EN

Design of supersonic HI rocket by the Rocketry Group of Students' Space Association (SR SKA) requires an analysis of thermal phenomena occurring in the elements particularly exposed to the high temperature gas. This paper contains a description of the methodology and the results of numerical simulation of heat transfer in the elements of the rocket head. The starting points were the flight conditions (3 characteristic points defined by altitude and Mach number) and independently calculated adiabatic temperature field of the gas. ANSYS Fluent code was used to determine the temperature field on the surface of the rocket. Computed cases were viscous and inviscid flow (for comparison). Based on the results formulated for the viscous case heat transfer boundary conditions, the numerical model and the thermophysical properties of materials were defined. The model was limited to a brass top part of the head and a part of a composite dome. Analytical and empirical method of "intermediate enthalpy" determined distribution of the heat transfer coefficient on the rocket surface. Then the transient heat transfer was calculated with the ANSYS system. It included the range from the rocket launch, moment of maximum Mach number to sufficient structure cooling. The results of the analyses were conclusions relevant to the further development work. Excessive heating of composite structures during the flight has been shown.

PL

Niniejszy artykuł zawiera opis metody oraz wyniki numerycznej symulacji wymiany ciepła w elementach głowicy rakiety. Punkt wyjścia stanowiły założone warunki lotu (3 punkty charakterystyczne określone przez wysokość i liczbę Macha) i wyznaczone niezależnie adiabatyczne pole temperatury gazu. Do wyznaczenia pola temperatur na powierzchni rakiety użyty został system ANSYS Fluent. Zostały' obliczone przypadki przepływał lepkiego i nielepkiego (dla porównania). Na podstawie wyników* dla przypadku lepkiego sformułowano warunki brzegowe wymiany ciepła, założenia modelu numerycznego. Model ograniczono do mosiężnej części noskowej i fragmentu kompozytowej kopułki. Metodą analityczno-empiryczną „średniej entalpii" (intermediate enthalpy) wyznaczono rozkład współczynnika przejmowania ciepła na powierzchni rakiety. Następnie dokonano obliczenia nieustalonej wymiany ciepła z wykorzystaniem systemu ANSYS. Obejmowały one zakres od startu rakiety, poprzez moment osiągnięcia maksymalnej liczby Macha, do wystarczającego schłodzenia konstrukcji. Efektem pracy było sformułowanie wniosków istotnych z punktu widzenia dalszych prac konstrukcyjnych, wykazano nadmierne ogrzewanie elementów kompozytowych w trakcie lotu.

2

Contacts Erosion Modelling Using Ansys Computer Software And Experimental Research

Borkowski P., Sienicki A.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

551--560

EN

The paper presents a method of contacts’ erosion modelling by using computer simulation and analyzing heating, melting and evaporation processes, which cause contact erosion due to application of electric arc. Calculations have been conducted using professional ANSYS software which allows for thermal processes simulation and includes phase transitions for Ag, Cu, W metals and Ag-W50 composite.

PL

Artykuł przedstawia metody modelowania erozji stykowej z wykorzystaniem symulacji komputerowej i analizy procesów nagrzewania, topnienia i parowania, które powodują erozję styków pod wpływem oddziaływania łuku elektrycznego. Obliczenia zostały przeprowadzone za pomocą profesjonalnego programu komputerowego ANSYS, który pozwala na symulację procesów termicznych z uwzględnieniem przemian fazowych dla styków wykonanych z metali: Ag, Cu, W, a także kompozytów Ag-W50.

3

Numerical and experiment study of residual stress and strain in multi-pass GMA welding

Chand R.R., Kim I.S., Lee J. P., Kim Y.S., Kim D. G.

Journal of Achievements in Materials and Manufacturing Engineering

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2013

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Vol. 57, nr 1

31--37

EN

Purpose: Recently, manufacturing industries have been concentrated on selection an optimal of welding parameter and condition that reduces the risk of mechanical failures on weld structures should be required in manufactory industry. In robotic GMA (Gas Metal Arc) welding process, heat and mass inputs are coupled and transferred by the weld arc to the molten weld pool and by the molten metal that is being transferred to the weld pool. The amount and distribution of the input energy are basically controlled by the obvious and careful choices of welding process parameters in order to accomplish the optimal bead geometry and the desired mechanical properties of the quality weldment. The residual stress and welding deformation have the large impact on the failure of welded structures. Design/methodology/approach: To achieve the required precision for welded structures, it is required to predict the welding distortions at the early stages. Therefore, this study represented 2D Finite Element Method (FEM) to predict residual stress and strain on thick SS400 steel metal plate. Findings: The experiment for Gas Metal Arc (GMA) welding process is also performed with similar welding condition to validate the FE results. The simulated and experiment results provide good evidence that heat input is main dependent on the welding parameter and residual stress and distortions are mainly affected by amount on heat input during each weld-pass. Practical implications: This present study on based on the numerical analysis using ansys software, for a thick multi-pass GMA welding. A birth and death technique is employed to control the each weld pass welding. Originality/value: The developed 2D multi-pass model employs Goldak’s heat distribution, to simulate welding on SS400 steel butt-weld joint with a thickness of 16mm. moreover the numerical results are validated with experiment results.

4

Finite Element Implementation of Damage Models for Composite Structures

Žmindák M., Riecky D., Danišovič S.

Machine Dynamics Research

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2010

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Vol. 34, No. 4

130-138

EN

This paper presents numerical modelling of composite damage by finite element method (FEM). The damage model is implemented it in ANSYS software for a one dimensional bar element. A return mapping algorithm integration is implemented in conjunction with plane stress element PLANE182. These subroutines should be linked with the ANSYS program beforehand.