• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.2
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• pp.23-35
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• 2003

"Backhole" is a new geometric parameter and is defined as an extra empty volume which is located behind the tangential entries at the rear part of the vortex chamber in the swirl injector. Backhole makes a difference to the spray characteristics of swirl injectors such as the spray angle, SMD, the mixing characteristics and so on. To find its characteristics, experiments are conducted by using a stroboscopic photography, a PDPA apparatus and a mechanical patternator. With the backhole, the mass flow rate of the swirl injector is increased and the center region of the injected flow has more large volume than that of without the backhole. Also the cone angle can be controlled by the backhole, so that the mixing efficiencies of swirl injectors are changed. Based on cold-flow tests, the swirl injector with the backhole may improve its performance.rformance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.225-234
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• 2001

This paper represents the vector fields, three dimensional mean velocities, the turbulent intensities, the turbulent kinetic energy, and the Reynolds shear stresses in the X-Y plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rates 350 and 450ℓ/min respectively, which are equivalent to the combustion air flow rate necessary for heat release 15,000 kcal/hr in gas furnace, in the test section of subsonic wind tunnel. The vector plot shows that the maximum axial mean velocity component exists in the narrow slits situated radially on the edge of gas swirl burner, for that reason, there is some entrainment phenomena of ambient air in the outer region of burner. Moreover, mean velocities in the initial region are largely distributed near the outer region of burner at Y/R≒0.97, but they diffuse and develop into the center flow region of burner according to the increase of axial distance. The turbulent intensities and the turbulent kinetic energy due to large inclination of mean velocity and swirl effect show that the maximum value in the initial region of burner is formed in the narrow slits situated radially on the edge of gas swirl burner and large values are mainly formed in the entire region of burner after X/R=2.4358, hence, the combustion reaction is anticipated to occur actively near this region. And the Reynolds shear stresses are also largely distributed from slite to vanes of gas swirl burner in the intial region, but their values largely disappear after X/R=3.2052.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.99-104
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• 2006

We introduce a novel contrast mechanism for imaging superparamagnetic iron oxide (SPIO) nanoparticles (average diameter ${\sim}100nm$) using magneto-motive optical Doppler tomography (MM-ODT), which combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect the nanoparticles flowing through a glass capillary tube. A solenoid cone-shaped ferrite core extensively increased the magnetic field strength ($B_{max}=1\;T,\;{\Delta}|B|^2=220T^2/m$) at the tip of the core and also focused the magnetic force on targeted samples. Nanoparticle contrast was demonstrated in a capillary tube filled with the SPIO solution by imaging the Doppler frequency shift which was observed independent of the flow rate and direction. Results suggest that MM-ODT may be a promising technique to enhance SPIO nanoparticle contrast for imaging fluid flow.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.3
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• pp.48-62
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• 1988

A triple hot-wire probe has an essential potentiality for the measure- ment of an instantaneous velocity vector in a three dimensional unsteady flow with large amplitude of velocity fluctuations, the key problems asso- ciated with this instrument are the directional range of applicability and the accuracy. This present paper is concerned with a new method of the techniques of calibration and data processing to estimate the three dimensional flow field using an arbitrary shaped triple hot-wire probe. The method is not based on the assumptions of orthogonality or symmetry and it is especially useful for applications to a hand-made probe where probe geometry is not accurately known. The test application is made to evaluate the effect of cone angles of symmetric non-orthogonal probe.

• 한국전산유체공학회:학술대회논문집
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• 2001.10a
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• pp.132-137
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• 2001

We used In-line orifice mixer for efficient chemicals mixing in water treatment. The method of using In-line orifice mixer has been already proved the improvement of water treatment efficiency. Code of computational fluid dynamics for numerical analysis was performed using FLUENT, a commercial code. As variable for exactly standardizing, a proper ratio between an outer diameter of deflector and a diameter of pipe, the distance between deflector and orifice, a determination of orifice diameter fur an optimal mixing, a distance between injection nozzle's position and cone, Numerical study has been performed for optimal standard and analyzed flow field on a basis of turbulent intensity in an orifice downstream.

• 한국전산유체공학회:학술대회논문집
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• 2000.05a
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• pp.172-177
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• 2000

In this numerical work, three dimensional supersonic laminar flow and heat transfer of a blunt body(sphere-cone) at Mach 5 is simulated. The effects of angle of attack and the spin rate on the now and heat transfer are analysed. To solve the three dimensional compressible Wavier-Stokes equation, a finite volume method with the modified LDFSS scheme is employed for spatial discretization, and a point SGS implicit method is used for time integration. It is found that the heat transfer rate increases at the windward side and decreases at the leeward side with the angle of attack. The heat transfer rate at all surfaces slightly increases with the spin rate.

• Journal of computational fluids engineering
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• v.1 no.1
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• pp.123-141
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• 1996

In this paper the upwind flux difference splitting Navier-Stokes method has been applied to study the perfect gas and the equilibrium chemically reacting hypersonic flow over an axisymmetric sphere-cone(5°) geometry. The effective gamma(γ), enthalpy to internal energy ratio was used to couple chemistry with the fluid mechanics for equilibrium chemically reacting air. The test case condition was at altitude(30km) and Mach number(15). The equilibrium shock thickness over the blunt body region was much thinner than that of perfect gas shock. The pressure difference between perfect gas and equilibrium gas was about 3 ∼ 5 percent. The heat transfer coefficient were also calculated. The results were compared with VSL results in order to validate the current numerical analysis. The results from current method were compared well VSL results ; however, not well at near nose. The proper boundary condition and grid system will be studied to improve the solution quality.

• 한국전산유체공학회:학술대회논문집
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• 1995.10a
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• pp.203-212
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• 1995

In this paper the upwind flux difference splitting Navier-Stokes method has been applied to study the perfect gas and the equilibrium chemically reacting hypersonic flow over an axisymmetric sphere-cone($5^{\circ}$) geometry. The effective gamma($\bar{r}$), enthalpy to internal energy ratio was used to couple chemistry with the fluid mechanics for equilibrium chemically reacting air. The test case condition was at altitude(30Km) and Mach number(15). The equilibrium shock thickness over the blunt body region was much thinner than that of perfect gas shock. The pressure difference between perfect gas and equilibrium gas was about $3\sim5$ percent. The skin friction coefficient and heat transfer coefficient were also calculated.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.437-441
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• 2010

LES results of turbulent premixed combustion flows are introduced by using the dynamic sub-grid scale model based on G-equation describing the flame front propagation. The turbulent premixed combustion flows around bluff body and over backward facing step are analyzed to validate present formation. LES of swirling partially premixed combustion flame is also performed to conform the predictive capabilities of LES model and to prompt our understanding for the combustion flows over double cone swirl burner combustor by using CFD-ACE+ commercial code.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.316-320
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• 2003

This paper introduces an autonomous underwater vehicle (AUV) model, ASUM, equipped with a visual servo control system to dock into an underwater station with a camera and motion sensors. To make a visual servoing AUV, this paper implemented the visual servo control system designed with an augmented state equation, which was composed of the optical flow model of a camera and the equation of the AUV's motion. The system design and the hardware configuration of ASUM are presented in this paper. ASUM recognizes the target position by processing the captured image for the lights, which are installed around the end of the cone-type entrance of the duct. Unfortunately, experiments are not yet conducted when we write this article. The authors will present the results for the AUV docking test.