• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.202-205
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• 2011

A rotating propeller of turboprop aircraft gives much effect on the aerodynamic characteristics of wing such as lift, moment and stall. Specially, a rotating propeller changes the lift and moment characteristics when aircrafts are in landing or take-off condition. In the present paper, 3-dimensional Navier-Stokes simulations for the interaction of propeller and wing were carried out. For rotating propeller, unsteady sliding mesh method was used to simulate a relative motion. For the power effect analysis in landing and take off configurations, double slotted flap was also considered and the aerodynamic characteristics were investigated. It was shown that the propeller slipstream enhanced the lift slope including maximum lift and this enhancement was more dominant with high lift device.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.31-40
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• 2011

Unsteady sheet cavitation on a three-dimensional twisted hydrofoil was studied using an unsteady Reynolds-averaged Navier-Stokes equations solver based on a cell-centered finite volume method. As a verification test of the computational method. non-cavitating and cavitating flow over a modified NACA66 foil section was simulated and validated against existing experimental data. The numerical uncertainties of forces and pressure were evaluated for three levels of mesh resolution. The computed pressure on the foil and the cavity shedding behavior were validated by comparing with existing experimental data. The cavity shedding dynamics by re-entrant jets from the end and sides of the cavity were investigated.

• Journal of computational fluids engineering
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• v.19 no.1
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• pp.80-86
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• 2014

Numerical investigation on the dynamic stall over an oscillating airfoil is presented. A Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with transition transport equations for the natural transition. Computational results considering the turbulent transition are compared with the fully turbulent computations and the experimental data. Results with transition prediction show closer correlation with the experimental data than those with the fully turbulent assumption, especially in the reattachment region.

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.8-16
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• 2014

Two-dimensional prediction capability of several analysis codes, such as XFOIL, MSES, and KFLOW, is compared and analyzed based on computational results of airfoil flows. To this end the transition transport equations are coupled with the Navier-Stokes equations for the prediction of the natural transition and the separation-induced transition. Experimental data of aerodynamic coefficients are used for comparison with numerical results for the transitional flows. Numerical predictions using the transition transport model show a good agreement with experimental data. Discrepancies have been found in the prediction of the pressure drag are mainly caused by the difference in the far-field circulation correction methods.

• Journal of computational fluids engineering
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• v.19 no.2
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• pp.93-98
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• 2014

In the present study, CFD methods are applied in the design procedure of rotor blades in a axial-flow fan and the aerodynamic performances are predicted. The blade profiles initially determined by the free vortex method and empirical formula are modified to match the target value of the rotor work load through the analysis of 3D Navier-Stokes solver. The corrected shapes of the rotor blade showed the increase of the efficiency and the pressure simultaneously.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.735-745
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• 2004

A linear cascade of NACA 65-1810 profiles are investigated for tip leakage flow characteristics. and calculation results are compared with experimental result. STAR-CD commercial code was used to solve the three dimensional incompressible Navier-Stokes equation that was adopted for steady flow and high Reynolds $\kappa$- $\varepsilon$turbulent model. Numerical calculation of a linear cascade is carried out to investigate effect of tip clearance on pitchwise variations of velocity Profiles. and static pressure distributions on the blade surface at spanwise positions. In case of evolution of tip vortex core location. tip vortex geometry and static pressure at the center of the tip vortex core compared with experimental results. Calculation results are agreed well with the experimental data, and validated. The static pressure losses by tip leakage flow at 2% tip clearance were more than those at 1% tip clearance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.12
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• pp.1774-1783
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• 1998

The transition from steady laminar to chaotic convection in a glass melting furnace specified by upper surface temperature distribution has been studied by the direct numerical analysis of the two and three-dimensional time dependent Navier-Stokes equations. The thermal instability of convection roll may take place when modified Rayleigh number($Ra_m$) is larger than $9.71{\times}10^4$. It is shown that the basic flows in a glass melting furnace are steady laminar, unsteady periodic, quasi-periodic or chaotic flow. The dimensionless time scale of unsteady period is about the viscous diffusion time, ${\tau}_d=H^2/{\nu}_0$. Through primary and secondary instability analyses the fundamental unsteady feature in a glass melting furnace is well defined as the unsteady periodic or weak chaotic flow.

• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.267-279
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• 2003

The present investigation deals with the application of Adomian's decomposition method to blood flow through a constricted artery in the presence of an external transverse magnetic field which is applied uniformly. The blood flowing through the tube is assumed to be Newtonian in character. The expressions for the two-term approximation to the solution of stream function, axial velocity component and wall shear stress are obtained in this analysis. The numerical solutions of the wall shear stress for different values of Reynold number and Hartmann number are shown graphically. The solution of this theoretical result for a particular Hart-mann number is compared with the integral method solution of Morgan and Young［17］.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.128-137
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• 1998

In this numerical experiment, the preconditioned compressible Navier-Stokes equation is tested to analyze the laminar spray combustion. Sprayed flow field is formulated by Eulerian-Lagrangian system for the gas and liquid phases each. DSF(Deterministic Separated Flow) model was adopted for the sprays with the vortex model to describe transients of individual droplet heating. Simplified single global reaction model approximates methanol-air reaction with and without disk flame holder. The equation system is discretized by finite difference technique and time integrated by LU-SGS. Due to greatly simplified chemical reaction mechanism and the lack of experimental evidences, most of the efforts were devoted to show the applicability and robustness of preconditioned compressible flow calculation algorithm. Computation results in qualitatively reasonable combusting flow field, hence it is believed that further refinement are required to produce quantitatively accurate solutions.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.149-152
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• 2007

The numerical simulations on the heat transfer and flow field were carried out for the improvement of the performance of the shell and tube heat exchanger. The steady incompressible 3-D Navier-Stokes solution is obtained with the actual operational condition and geometry of the heat exchanger. The present geometry of the heat exchanger causes poor heat transfer since the air inside shell dose not flow through the tube bundle, but around it. The enhancement of the heat transfer can be achieved by the variation of the design factor like the sealing strip located on the top/bottom and middle of the baffle.