GOSA Institute

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Institute Gosa is R&D institution dedicated to multidisciplinary, basic and applied researches. The institute is located in three places, Belgrade, Smederevska Palanka and Kladovo and organized by six Centers.

Center for Software Engineering deals with the application software in the following fields: research, development, simulation and optimization of processes and products, design and construction, analysis of the load, analysis and simulation of flow, elasto-mechanical simulation, education in the areas of information technology in mechanical techniques, application of computer design etc.

Institute Gosa has long lasting and constructive cooperation with the SimTec. The experts from the SimTec kindly give their support through education, technical support, practical support and consulting in numerical simulations applications based on SimTec expert’s great experience.

Project 1. Investigation and Optimization of the Technological and Functional Performance of the Ventilation Mill in the Thermal Power Plant Kostolac B

Institutee Gosa is the coordinator of projects No Tr 19205 and No. TR-34028, financially supported by the Ministry of Science and Technological Development and Ministry of Education and Science of Serbia.

Modern thermal power plants are complex systems where multiphase flow of recirculation gases, coal powder, sand and other materials directly influences ventilation efficiency of the mill, and the wearing of the plant vital parts. Numerical 3D simulations of multiphase flow (dilute gas-solid), around grinding wheel, louver and centrifugal separators, were performed using the Euler-Euler and Euler-Lagrange approach of ANSYS FLUENT software package (Upper Image and Image 1). An unstructured tetrahedral grid consisted of 2 996 772 volume and 706 444 surface elements is generated. The geometry of the model is faithful to the original design. The results obtained in the numerical simulation serve for selecting optimal redesign of the separators and impact plates.

For example, the experimental tests (in real exploitation conditions) of redesigned mill wearing parts show that the proposed modification (based on numerical flow simulation results), give good results (Image 2), that means, the application of numerical flow simulation results, can reduce the number of possible repairs and extends the period between them, resulting in significant economic effects.

Project 2. Optical and Numerical Visualization of Supersonic 2D Nozzle Flow

Institute Goša and VTI from Belgrade, performed, experimental and numerical flow visualization in the 2D supersonic, symmetric, convergent divergent nozzle with barriers mounted at the exit nozzle plane with different heights hd and angles αd. The experiment was performed in a supersonic wind tunnel and a combined device is used to make shadow, schlieren and holographic interferometry flow visualization. The main aim of the tests is to investigate the influence of the barrier on the flow, especially on the location of the shock wave.

The supersonic flow in the nozzle is numerically simulated by the solution of the Reynolds-Averaged Navier-Stokes equations with a two-equation k-ω turbulent model. This model of turbulence is based on the Boussinesq approximation. ANSYS Fluent softwere is used. Several mixed structured-unstructured grids of different resolutions (from a grid with 29884 to the finest one with 583000 cells) are used in the computations. The dimensionless distance of the first row of cells from the surface is y+ = O(1) in order to capture the viscous sublayer.

The results of the experimental visualization are presented by shadow, schlieren and interferograms of the flow field (Image 2). Numerical results by isodensity, iso Mach and isopressure line and velocity vectors are presented in Image 3.

Project 3. Scientific and Technological Support for the Improvement of Special of Road Safety and Rolling Stock

Throught the R&D project of the Ministry of Science and Technological Development, Republic of Serbia, TR 35045, Scientific and Technological Support for the Improvement of Special of Road Safety and Rolling Stock, that is leading by the Mechanical Faculty of University of Belgrade, numerical simulations over the high speed train (HST) are performing. One of the present research goals is impact of the aerodynamic brakes on the train braking force, since this kind of brakes is in use for extreme emergencies – rapid stopping.

Numerical simulations were performed by ANSYS Fluent. In this stage of study, it was assumed that flow is symmetrical over the full scale HST half model. Overall viewed period was 2 sec by witch was flow considered as transient flow of viscous incompressible fluid, fully turbulent. k–ε Realizable turbulence model was in use.

This part of research include the HST in several configurations, with/without aerodynamic brakes over the roof, for a series of their different relative positions to the train body and a series of speeds. Results from simulations, for various speeds for different configurations, were compared as well as exploring the phenomenon of serial interference, for the configuration of train with three distanced aerodynamic brakes.