Моделирање и нумеричке симулације вихорних струјања
Modeling and numerical simulations of swirling flows
Author
Ćoćić, AleksandarMentor
Čantrak, SvetislavCommittee members
Crnojević, CvetkoIvetić, Marko
Stevanović, Nevena
Lečić, Milan
Metadata
Show full item recordAbstract
Вихорна струјања су веома присутна у техничкој пракси...
Swirling flows are very common in technical practice. Flows in turbomachinery
and rotating systems, flows in pipelines after local resistances, flows of air in cyclones
and combustion chambers are just few examples of swirling flows in technical practice.
Turbulence structure in swirling flows are highly inhomogeneous and anisotropic. In
most cases turbulent models based on Boussinesq, linear eddy viscosity assumption,
give poor results. That is specially pronounced in case of Rankine type profile for
circumferential velocity. Reynolds stress models give better results in prediction of
swirling flows, but their usage in complex geometries are very demanding from the
viewpoint of solution convergence and time of calculation. In this thesis main accent
of research is on numerical simulations of swirling flows by use of various turbulent
models, and on theoretical analysis of the models and numerical methods which
are used for computations. An open-source software OpenFOAM was used for al...l
computations. Due to openness of the OpenFOAM code, it’s possible to analyze
the way of implementation of various mathematical models. Based on the code
analysis, Speziale-Sarkar-Gatski (SSG) Reynolds stress model was implemented in
OpenFOAM code. Also, some additional postprocessing tools and applications were
created and implemented in the code. Two problems are considered: axisymmetric
swirl flow in long circular pipe with Rankine profile of circumferential velocity, and
three-dimensional swirl flow in the pipe behind axial fan. In first problem, swirl
generator wasn’t considered, and experimental results in one cross-section were used
as boundary condition at the inlet. As a validation tool for numerical computations,
experimental results in other cross-sections were used. Several turbulent models
were tested on this problem. From class of two equation models k-", RNG k-",
Launder-Sharma k-" and k-! SST models were used, while from Reynolds stress
models class Launder-Reece-Rodi (LRR), Launder-Gibson (LG) and SSG model
were used. It was shown that all two-equation models give poor results, both for
profiles of mean velocities, and for turbulent kinetic energy. Reynolds stress models
give better results for mean velocity profiles...
Faculty:
Универзитет у Београду, Машински факултетDate:
10-07-2013Projects:
- Application of Novel Measurement and Computational Techniques on Investigation of Air Flow in Ventilation Systems of Energy Extremely Efficient (“Passive”) Buildings (RS-MESTD-Technological Development (TD or TR)-35046)