• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.621-626
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• 2003

This paper is concerned with the numerical analyses of an S-shaped duct for the inter-channel between compressor spools. For the compactness and lightweight of an engine, the length of the S-shaped duct is desired to be minimized. Shortening the S-shaped duct however, flow separation is likely to occur. Numerical investigation using a three-dimensional Navier-Stokes flow solver has been performed to determine the availability of the minimization of an S-shaped duct. Computations are performed introducing the experimental data as the inlet flow condition of the OGV in determining the minimum length of the S-shaped duct. Also, the leaning effect of the OGV which assists the flow to turn radially inward are studied adopting mixing-plane method to consider the rotor/OGV interaction.

• The KSFM Journal of Fluid Machinery
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• v.13 no.4
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• pp.25-30
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• 2010

Flow analysis and performa nce evaluation have been performed for a ventilation axial-flow fan with different positions of the motor. Two different positions of motor have been tested; one is in front of the impeller and the other is behind the impeller. Flow analyses are performed by solving three-dimensional Reynolds-averaged Navier-Stokes equations through a finite-volume solver. Preliminary numerical calculations are carried out to test the performances of different turbulence models, i.e., SST model, k-$\omega$ model, and k-$\varepsilon$ model with and without using empirical wall function in the flow analysis. The validation of numerical analyses has been performed in comparison with the experimental data. The numerical results for the performance characteristics of the ventilation axial-flow fan with two different positions of the motor have been presented.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.5
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• pp.17-23
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• 1995

A numerical analysis on engine coolant is made by the use of FVM based general purpose 3 dimensional Navier-Stokes solver, TURB-3D. Numerical solutions are verified by comparison with the experimental data of Lotus model. The results show a good qualitative as well as quantitative comparison. Coolant flow rate control is attempted through adjusting the cross section area of passage base on the results of an original coolant passage. It is concluded from the results that the flow rate control is possible as attempted, and thus can be used in the real engine design.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.269-272
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• 2006

Numerical analysis of wind turbine scale effect was performed by using computational fluid dynamics. For the numerical analysis of wind turbine. Three dimensional Navier-Stokes solver with various turbulence models was tested and realizable k-e turbulence model was selected for the simulation of wind turbines. To validate the present method, performance of NREL (National Renewable Energy Laboratory) Phase VI wind turbine model was analyzed and compared with experiment and blind test data. Using the present method, numerical simulations for various size of wind tunnel model were carried out and characteristics were observed in detail. The power loss due to the interference between wind turbine and nacelle was also computed for relatively larger nacelle installation in wind tunnel test. The present results showed good correlations with experimental data and reasonable trends of scale effect of wind turbine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.78-81
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• 2008

A numerical study of the unsteady flow in an over-expanded thrust optimized contour and compressed truncated perfect rocket nozzle is carried out in present paper. These rocket nozzles are subject to flow separation in transient phase at engine start-up and/or engine shut-down. The separation flow structures at different pressure ratios are observed. The start-up process exhibits two different shock structures such as FSS (Free Shock Separation) and RSS (Restricted Shock Separation). For a range of pressure ratios, hysteresis phenomenon occurs between these two separation patterns. A three-dimension compressible Navier-Stokes solver is used for the present study. One equation Spalart-Allmaras turbulence model is selected. The computed nozzle wall pressures show a good agreement with the experimental measurements. Present results have shown that present code can be used for the analysis of the transient flows in nozzle.

• Ocean Systems Engineering
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• v.9 no.1
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• pp.43-77
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• 2019

A local-analytic-based Navier-Stokes solver has been employed in conjunction with a compound ocean structure motion analysis program for time-domain simulation of passing ship effects induced by multiple post-Panamax class ships in the exact condition of a real waterway. The exact seabed bathymetry was reproduced to the utmost precision attainable using the NOAA geophysical database for Virginia Beach, NOAA nautical charts for Hampton Roads and Norfolk harbor, and echo sounding data for the navigation channel and waterfront facilities. A parametric study consists of 112 simulation cases with various combinations of ship lanes, ship speeds, ship heading (inbound or outbound), channel depths, drift angles, and passing ship coupling (in head-on or overtaking encounters) were carried out for two waterfront facilities at NAVSTA Norfolk and Craney Island Fuel Terminal. The present paper provides detailed parametric study results at both locations to investigate the site-specific passing ship effects on the motion responses of ships moored at nearby piers.

• Advances in aircraft and spacecraft science
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• v.6 no.1
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• pp.19-30
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• 2019

Two- and three-dimensional turbulent airflows in a 9-degrees-bent channel are studied numerically. The inner surfaces of upper and lower walls are parallel to each other upstream and downstream of the bend section. The free stream is supersonic, whereas the flow at the channel exit is either supersonic or subsonic depending on the given backpressure. Solutions of the Reynolds-averaged Navier-Stokes equations are obtained with a finite-volume solver ANSYS CFX. The solutions reveal instability of formed shock waves and a flow hysteresis in considerable bands of the free-stream Mach number at zero and negative angles of attack. The instability is caused by an interaction of shocks with the expansion flow formed over the convex bend of lower wall.

• Advances in Computational Design
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• v.6 no.1
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• pp.43-53
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• 2021

Multi-stage pumps are the most popular pumps among various kinds of centrifugal pumps. Athorough review of different kinds of literature has led to the conclusion that there is a desperate need to increase the performance of the multi-stage centrifugal pump. Many investigators have put their efforts to increase the pump performance and also the work is being projected on various aspects of pump performance variables. To improve the multistage centrifugal pump performance by investigation, modification, and analysis many works of literature are available. For analysis, many researchers used the Navier-Stokes solver to create the three-dimensional unsteady turbulent flow numerical model with the standard k-ε turbulent equation. This paper mainly focuses on research related to the multi-stage centrifugal pump.

• Journal of Aerospace System Engineering
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• v.15 no.2
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• pp.10-15
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• 2021

The propeller wake of tiltrotor-type aircrafts, such as TR-60 and quad tilt propeller (QTP) UAV, in hover substantially impinges the upper surface of the primary wing and generates a downward load. This load is directly proportional to the thrust of the propeller and reduces the available payload. Therefore, wing and nacelle mechanisms should be carefully designed to reduce downward load. This study conducted a numerical analysis of the rotating propeller in hover to predict the downward load of a QTP UAV. An unsteady three-dimensional Navier-Stokes solver was used along with a sliding mesh for the simulation of the rotating propeller. To reduce the downward load, the tilting mechanisms of the partial wing and nacelle were simultaneously introduced and numerically analyzed. Finally, the downward load was predicted by 14% of isolated propeller thrust; further, the downward load could be reduced by adopting the partial wing and nacelle tilting concept.

• Ocean Systems Engineering
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• v.13 no.1
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• pp.1-20
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• 2023

An iterative focused wave generation method is developed and implemented in a local analytic based Navier-Stokes solver. This wave generation method is designed to reproduce the target focused wave by matching the target amplitude spectrum and phase angle. A 4-waves decomposition scheme is utilized to obtain the linearised component of the output wave. A model test studying the interaction between different focused waves and a fixed cylinder is selected as the target for the wave generation approach. The numerical wave elevations and dynamic pressure on the cylinder are compared with the experimental measurement and other state-of-the-art numerical methods' results. The overall results prove that the iterative adjustment method is able to optimize the focused wave generated by a CFD approach.