• Journal of computational fluids engineering
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• v.21 no.2
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• pp.70-80
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• 2016

The comparison of two commercial codes(FLUENT and STAR-CCM+) and an open-source code(OpenFOAM) are carried out for the aerodynamic analysis of flight vehicles at low speeds. Tailless blended-wing-body UCAV, main wing and propeller of HALE UAV(EAV-3) are chosen as geometries for the investigation. Using the same mesh, incompressible flow simulations are carried out and the results from three different codes are compared. In the linear region, the maximum difference of lift and drag coefficients of UCAV are found to be less than 2% and 5 counts, respectively and shows good agreement with wind tunnel test data. In a stall region, however, the reliability of RANS simulation is found to become poor and the uncertainty according to code also increases. The effect of turbulence models and meshes generated from different tools are also examined. The transition model yields better results in terms of drag which are much closer to the test data. The pitching moment is confirmed to be sensitive to the existence and the location of transition. For the case of EAV-3 wing, the difference of results with ${\kappa}-{\omega}$ SST model is increased when Reynolds number becomes low. The results for the propeller show good agreement within 1% difference of thrust. The reliability and uncertainty of three codes is found to be reasonable for the purpose of engineering use. However, the physical validity and reliability of results seem to be carefully examined when ${\kappa}-{\omega}$ SST model is used for aerodynamic simulation at low speeds or low Reynolds number conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.373-380
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• 2017

In this study, we conducted computational fluid dynamics (CFD) simulations for the unsteady hydrodynamic interaction of multiple thrusters by solving Reynolds averaged Navier-Stokes equations. A commercial CFD software, STAR-CCM+ was used for all simulations by employing a ducted thruster model with combination of a propeller and No. 19a duct. A sliding mesh technique was used to treat dynamic motion of propeller rotation and non-conformal hexahedral grid system was considered. Four different combinations in tilting and azimuth angles of the thrusters were considered to investigate the effects on the propulsion performance. We could find that thruster-hull and thruster-thruster interactions has significant effect on propulsion performance and further study will be required for the optimal configurations with the best tilting and relative azimuth angle between thrusters.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.61-70
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• 2016

Dong-tan Station, shared by high-speed railway and urban express railway, is a very complicated underground station having 6 tracks together with barrier and shafts between them, therefore it seems very hard to investigate the aerodynamic effects including the pressure variation and train gust in the station when a high-speed train runs through it. In this study, the aerodynamic effects on the structures and platform passengers when a high-speed train runs through an underground station have been studied using Computational Fluid Dynamics. STAR-CCM+ has been employed for numerical simulation based on Navier-Stokes equation and 2-equation turbulence model and moving mesh scheme supported by STAR-CCM+ has also been used to represent the relative motion between a train and station. Based on the simulation results, the unsteady flow fields in the underground station induced by the high-speed train have been analyzed and the pressures on the PSDs and pressure variation at the platform have quantitatively assessed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.6
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• pp.750-757
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• 2016

This study presents the wave run-up height around single and multiple surface-piercing cylinders according to wave period and steepness. In order to simulate 3D incompressible viscous two-phase turbulent flow, the present study employed a volume of fluid (VOF) method with realizable $k-{\varepsilon}$ turbulence model based on commercial Computational Fluid Dynamics (CFD) software, "STAR-CCM". The wave periods at model scale were 1.269s and 1.692s for a single cylinder and 1.716s for multiple cylinders. In each case, wave steepness of has 1/30 and 1/16 were used, respectively. Consequently, the results for wave run-up height with regard to wave steepness and period were compared with those of relevant previous experimental studies. The numerical simulation results showed a good qualitative agreement with experiments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.3
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• pp.194-201
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• 2017

The KARI-11-180 airfoil was selected as a model for EFD-CFD comparison workshop case 1. Wind tunnel test for this model was conducted in KARI low speed wind tunnel with $0.6m{\times}3.0m$ model for the Reynolds number up to 3.0E6. The model configuration and wind tunnel test results including Cl, Cd and Cp were released at the KSAS 2015 spring conference. The computational analysis results with KFLOW, FLUENT and STAR-CCM+ were present in the KSAS 2015 fall conference. These computational works were summarized in this paper and the comparison results with each others including the wind tunnel data were also summarized.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.103-109
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• 2013

In this study, we performed a numerical study of hydrogen/air combustion in the combustion chamber of an ultra micro gas turbine. The supply flow rate and equivalence ratio are used as variables, and the commercial computational fluid dynamic program (STAR-CCM) is used for the numerical study of the combustion. The flow rate significantly affects the flame position, flame temperature, and pressure ratio between the inlet and the outlet. The flame position is close to the outlet in the combustion chamber, and the flame temperature and pressure ratio monotonously increases with the supply flow rate. The change in the equivalence ratio does not affect the flame position. The maximum flame temperature occurs under stoichiometric conditions.

• Journal of Navigation and Port Research
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• v.38 no.6
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• pp.585-591
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• 2014

The primary objective of the current work is to predict speed performance of the medium patrol boat over $F_N=0.5$ employing experimental materials based on the CFD before model tests. In other words, the predicted brake powers according to ship speeds are assessed satisfying the main engine capacity. The subject ships are selected the two different stern hull forms. The flow computation are conducted considering free surface and dynamic trim using a commercial CFD code(STAR-CCM+). The resistances of the bare-hull are obtained from CFD. Wave patterns, pressures and limiting streamlines on the hull and velocity distribution in the propeller plane for the two hull forms are compared using CFD. The effective powers of the object ships are assessed based on CFD. Resistance increase according to the attached appendages and quasi-propulsive efficiency are employed the experimental datas. Speed performance prediction method concerning high speed vessels like a medium patrol boat is developed employing CFD and experimental data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.876-883
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• 2016

In this study, we selected CFRP to construct a canoe hull. A ship design was made using a commercial ship design program, SOLIDWORKS, and a flow analysis of the canoe on a free surface was calculated using STAR-CCM+. A flow field and waveform were obtained in this way. These results were used to check the resistant performance of the canoe. Results showed that if the draft is 0.09 m, it is safe to run at less than 4 m/s, and if draft is 0.24 m, it is safe to run at less than 2 m/s. Moreover, it was confirmed that those speeds can be made by two adults. The developed canoe, which is 20 % lighter in comparison with conventional FRP models, was briefly introduced in this paper.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.791-798
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• 2016

In this study, numerical simulations on the effects of bilge keel on roll motion were conducted. The numerical simulations were performed on a 110 m class PSV using the commercial viscous flow analysis software Star-CCM+. Before conducting the study on the 110 m class PSV, an additional simulation of DTMB 5512 was performed and compared with the experimental results to validate the feasibility of the numerical simulation. In the simulation on PSV, a nondimensional damping coefficient was calculated using a free roll decay simulation, and the response amplitude operator (RAO) for the roll motion was calculated with a nondimensional damping coefficient at two conditions (with/without bilge keel).

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.20-27
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• 2017

The present paper describes the flow analysis of the flows around the multicopter for the selection of optimal position of air data sensor. For the flow analysis, the commercial fluid dynamics solver, STAR-CCM+ was used with polygon mesh and k-w SST turbulence modeling options. For the simulation of each rotating 4 propellers, unstructured overset mesh method was used. Hovering, forward flight, ascending and descending flight conditions are selected for the analysis and airspeed and flow angle errors were investigated using the CFD results. Through the flow field analysis, sensor location above one propeller diameter distance from the propeller rotating plane showed airspeed error less than 1m/s within the typical flight conditions of multicopter except descending.