• Journal of computational fluids engineering
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• v.15 no.3
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• pp.60-65
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• 2010

In the present study, the effects of the stagger angles on the aerodynamic performances in the vaned centrifugal compressor has been investigated by CFD methods. The diffuser vane angles were varied in the range of ${\pm}10$ deg. from the initial-design points. The commercial Navier-Stokes solver, ANSYS-CFX were applied to solve the impeller-diffuser flowfields. Through the numerical results, the desirable setting angles were proposed to fit the best performance to the variation of the operating conditions.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2168-2173
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• 2003

Pressure balancing valve is one of important control devices, which is fully automatic and no manual controls, regulating or adjustments are needed. It is typically used to maintain constant temperature of working fluid in power and chemical plants and domestic water supply systems. Pressure balancing valve is composed of body, cylinder and balancing piston. Therefore, the balancing piston shapes are important design parameters for a pressure balancing valve. In this study, numerical and experimental analyses are carried out with two different balancing piston shapes. Especially, the distribution of static pressure is investigated to calculate the flow coefficient($C_v$). The governing equations are derived from making using of three-dimensional Navier-Stokes equations with standard ${\kappa}-{\varepsilon}$ turbulence model and SIMPLE algorithm. Using commercial code, PHOEIC, the pressure and flow fields in pressure balancing valve are depicted.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.97-100
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• 2006

An ejector is designed for the purpose of engine bay cooling and exhaust gas cooling. The primary flow of the ejector is the exhaust gas of the turboshaft engine. The mass flow of secondary flow is calculated by using the approximate analytic equation. For the purpose of verification of approximate method, comparison is made with the results of Navier-Stokes turbulent flow solution. According to the results of CFD, the mixing of two flows is incomplete due to the short length of mixing duct.

• Journal of computational fluids engineering
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• v.17 no.1
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• pp.16-22
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• 2012

Acoustic pressure field around the centrifugal fan is predicted by a aero-acoustic splitting method. Unsteady flow field is obtained by solving the incompressible Navier-Stokes equations using commercial code, while the acoustic waves generated inside the centrifugal fan and shroud are predicted by solving the far field acoustics analysis. Computational results show that the acoustic waves of BPF tone are generated by interactions of the blades with the shroud. Acoustic results is validated by experimental results This paper describes the influence of geometric parameters on the noise generation from the section of blades and shroud. One of the effective ways to reduce BPF noise is optimization method using Genetic Algorithm, which effectively minimize eccentricity, is suggested. New improving design was developed by optimization method.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.127-130
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• 2002

Supersonic jet flow has been applied to many various industrial applications of manufacturing fields. Such a supersonic jet is generally classified by three flow patterns, depending on the flow state at nozzle exit, that is, under-, correctly- and over-expanded flows. Of these three flows, the correctly-expanded supersonic jet is most frequently used since it provides a maximum performance of a flow device. However detailed information on what conditions are the Jet correctly expanded at the exit of nozzle is not well known. In the current study, computations are applied to the axisymmetric, compressible, Navier-Stokes equations. The design Mach number used are 2.0,1.2 and 2.6. The computational results obtained are compared with the previous experimental ones. A theoretical analysis is conducted to predict the major features of the correctly-expanded jet. The results show that the jet core length is increased as Mach number is increased.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.457-464
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• 2001

The aeroacoustic phenomena in the simple rectangular open cavity are well published by many researchers. But the geometry shapes of aircraft landing gear wells, weapon bays, etc. are more complicate than that of the simple retangular cavity. They are more similar to the cavity having cover-plates at adges, or Helmholtz resonator. Therefore, the effects of cover-plates existing on edges of rectangular open cavity are numerically investigated in this paper. The compressible Navier-Stokes equations are solved for two-dimensional cavities with laminar boundary layers upstream. The high-order and high-resolution numerical schemes are used for the evaluation of spatial derivatives and the time integration. Physically correct numerical boundary conditions and buffer zone techniques are implemented to produce time-accurate solutions in the whole computation domain. The computational domain is large enough to directly resolve a portion of the radiated acoustic field. Results show that the cover-plates existing on edges of cavity reduce the noise convected from cavity, make the frequency of noise become higher, and change the directivity pattern. So these results can be used in the design of a low noise cavity.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.421-426
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• 2009

This paper describes on energy loss in a pipe of refuse collecting system. Analysis energy loss in a pipe is the decisive factor in a design for refuse collecting system. From the analysis energy loss, we can determine the capacity of turbo blower. The flow characteristics in the pipe with the refuse bag are analyzed by three-dimensional Navier-Stokes analysis. The refuse bag is modeled using the actual measurement. We obtain friction factor by changing refuse bag's size and mixing ratio and Reynolds number. And From the result we calculate energy loss by using compressible flow analysis.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.758-759
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• 2008

This paper presents a design of the electromagnetic pump with an tubular type linear induction motor(TLIM). The TLIM was designed for the fluid system, flow rate $15[{\ell}/min]$, and the thrust 39[N] at 0.29[m/s]. The TLIM is compared measurement with analysis. The electromagnetic pump of flow characteristics are calculated by treating TLIM thrust as a source term in the Navier-Stokes equation. The numerical analysis of flow characteristics of the liquid metal is presented for the various condition and discussed.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.119-122
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• 2005

In this paper a method for analysing aerodynamic characteristics of a rotating parachute in steady descending motion is presented. Because of a complex geometric configuration of the parachute associated with side vents and discontinuous skirts, special procedure was adopted th handle the geometry in the analysis. A panel method was successfully applied to the present problem and yielded good results using above procedure. A CFD code using the full Navier-Stokes equations was also applied and provided good results. Parachute free drop and wind tunnel tests were performed to determine the fully developed canopy configuration and aerodynamic characteristics. The method can be used for optimizing the parachute size and side vent configurations in the design period.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.152-155
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• 2008

In this paper, the effect of modification of geometric variables on the performance of a centrifugal compressor blade has been studied numerically. The compressor contains six main blades and six splitter blades. Reynolds averaged Navier-Stokes (RANS) equations with shear stress turbulence (SST) model are discretized by finite volume approximations and solved on hexahedral grids for flow analysis. The design variables from blade lean angle at tip and middle of the blade have been modified. The isentropic blade efficiency and pressure have been predicted with the variation of the variables. Frozen rotor simulation is performed and adiabatic wall condition has been used. One of the six blades of compressor has been used for simulation to reduce the computational load. Optimum number of meshes has been selected by grid-dependency test, and this is used for all the simulations with changing geometric variables. The detailed flow analysis results have been reported as well as the effects of the variables.