• Polymer(Korea)
• /
• v.36 no.5
• /
• pp.637-642
• /
• 2012

The effects of mixing geometry (intermeshing vs. tangential rotor) for the dispersion and distribution of silica agglomerates in SBR/BR compound were investigated. Silica dispersion and distribution were found to be better with the intermeshing rotor compared to the tangential rotor. It was concluded that the intermeshing rotor compared to the tangential rotor delivered a higher shear stress due to interlocked rotor geometry to silica agglomerates leading to better dispersity and distribution of silica in the agglomerates.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.10
• /
• pp.21-26
• /
• 2016

This study evaluates the magnitudes and distributions of contact tangential forces with the swaging depth of punch acting at the contact surfaces between a rotor core slot and a Cu bar during a sequential rotor core swaging process. The effects of the core slot shape on the magnitudes and distributions of the total contact forces were investigated to improve the productivity of the rotor core swaging process. Parametric elastic-plastic numerical analyses were performed using simplified two-dimensional cyclic symmetric plane strain models to evaluate the contact force distributions at the contact surfaces. The numerical analysis results show that the total contact tangential forces increased by about 55% with the adjacent Cu bar swaging process. The length of the core slot is a dominant factor in the core slot design as result of the increased total contact tangential forces during the swaging process of the rotor core.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.9
• /
• pp.1005-1014
• /
• 2004

Experiments were done for the three dimensional unsteady flow in a counter-rotating axial flow fan under peak efficiency operating condition. Flow fields in a counter rotating axial flow fan were measured at cross-sectional planes of the upstream and downstream of each rotor. Cross sectional flow patterns were investigated through the acquired data by the 45$^{\circ}$ inclined hot-wire. Flow characteristics such as tip vortex, secondary flow and tip leakage flow were confirmed through axial, radial and tangential velocity vector plot. It has been found that the radial and tangential velocity components disappeared, while the axial velocity component highly increased as soon as the tip vortex was generated. It has been observed that secondary flow and turbulence intensity which were increased by the front rotor were dissipated passing through the rear rotor. As the result the energy loss of the counter rotating axial flow fan decreased at the downstream of rear rotor. Also, it has been verified that tip vortex pattern of the rear rotor was dampened because the tip vortex generated by front rotor was mixed with that of the rear rotor.

• International Journal of Aeronautical and Space Sciences
• /
• v.10 no.2
• /
• pp.106-116
• /
• 2009

In order to investigate change of vortex structures and its evolving proceses, two dimensional LDV system was used for measurement of velocity vectors of tip vortex, and PIV system was also used for visualizations of tip vortex array for two bladed rotor, respectively. Experiments provided vortex locations, tangential and axial velocity components of tip vortex at six wake ages of 9.5, 10.5, 60.5, 99.5, 129.5, 169.5 and corresponded six wake ages shifted with 180 degrees per each. It was resulted that tip vortices generated by the first blade satisfy Landgrebe's model for their vortex locations even after they were accelerated by the second blade in downstream. Tangential velocity components of tip vortices follow Vatistas' n=2 model on both inside and outside regions of rotor slipstream without loss of vortex circulation. Axial velocity profiles revealed that there were small but significant perturbations just outside the primary vortex core which implies the second blade affects the wake substantially. It was also found that tip paths of each blade were not willing to be coincided intrinsically.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.790-798
• /
• 2008

Counter-rotating axial flow fan(CRF) consists of two counter-rotating rotors without stator blades. CRF shows the complex flow characteristics of the three-dimensional, viscous, and unsteady flow fields. For the understanding of the entire core flow in CRF, it is necessary to investigate the three-dimensional unsteady flow field between the rotors. This information is also essential to improve the aerodynamic characteristics and to reduce the aerodynamic noise level and vibration characteristics of the CRF. In this paper, experimental study on the three-dimensional unsteady flow of the CRF is performed at the design point(operating point). Flow fields in the CRF are measured at the cross-sectional planes of the upstream and downstream of each rotor using the $45^{\circ}$ inclined hot-wire. The phase-locked averaged hot-wire technique utilizes the inclined hot-wire, which rotates successively with 120 degree increments about its own axis. Three-dimensional unsteady flow characteristics such as tip vortex, secondary flow and tip leakage flow in the CRF are shown in the form of the axial, radial and tangential velocity vector plot and velocity contour. The phase-locked averaged velocity profiles of the CRF are analyzed by means of the stationary unsteady measurement technique. At the mean radius of the front rotor inlet and the outlet, the phase-locked averaged velocity profiles show more the periodical flow characteristics than those of the hub region. At the tip region of the CRF, the axial velocity is decreased due to the boundary layer effect of the fan casing and the tip vortex flow. The radial and the tangential velocity profiles show the most unstable and unsteady flow characteristics compared with other position of rotors. But, the phase-locked averaged velocity profiles of the downstream of the rear rotor show the aperiodic flow pattern due to the mixture of the front rotor wake period and the rear rotor rotational period.

• Tribology and Lubricants
• /
• v.15 no.1
• /
• pp.17-23
• /
• 1999

A Gerotor hydraulic motor is a planar mechanism consisting of a pair of rotors one of which encloses another rotor. The motion of the inner-rotor relative to the outer-rotor is produced by the pressure difference between the adjacent chambers. A design method of inner-rotor tooth profile using unit tangential vectors is presented in this work. Based on the relationships derived, the influence of the eccentricity of inner-rotor and the radius of circular arc tooth on the flow rate, torque and curvatures were investigated. It was shown that the flow rate and mean torque is proportional to eccentricity, but inversely proportional to the radius of circular arc teeth. Also, the maximum value of the equivalent curvature is increased as the eccentricity and the radius of circular arc teeth increased.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1997.04a
• /
• pp.111-121
• /
• 1997

The stability of a rotor-bearing system supported by swirl-controlled hybrid journal bearing with pair-type angled injection orifices is investigated for improvement of the whirl frequency ratio by allowing effective control of the tangential flow inside the bearing clearance, i.e., by achieving more freedom in controlling strength and direction of the supply tangential flow inside the bearing clearance. It is suggested that the system instability can be improved through the change of bearing dynamic characteristic parameters with the swirl control. The orifice diameter d$_0$ and recess injection angle $\alpha$ along with combinations of swirl/anti-swirl supply pressures and directions (3.0-3.0MPa, 4.0-2.0MPa, 2.0-4.0MPa) are selected for design parameters for swirl-controlled effective factors dependent on journal speeds (3000, 9000, 15000, 21000 rpm). It has been found that the orifice diameter do shows strong effects on effective maneuverability of direct-stiffness and direct damping values, while recess injection angle $\alpha$ results in substantial magnitude and direction of cross-stiffness. Specifically, recess injection parameters which are functions of angle of orifice feeding flow and recess dimensions showed very feasible effect on the stability of swirl-controlled rotor-bearing system.

• Tribology and Lubricants
• /
• v.13 no.3
• /
• pp.63-72
• /
• 1997

The stability of a rotor-bearing system supported by swirl-controlled hybrid journal bearing with pair-type angled injection orifices is investigated for improvement of the whirl frequency ratio by allowing effective control of the tangential flow inside the bearing clearance, i.e., by achieving more freedom in controlling strength and direction of the supply tangential flow inside the bearing clearance. It is suggested that the system instability can be improved through the change of bearing dynamic characteristic parameters with the swirl control. The orifice diameter $d_0$ and recess injection angle $\alpha$ along with combinations of swirl/anti-swirl supply pressures and directions (3.0~3.0 MPa, 4.0~2.0 MPa, 2.0~4.0 MPa) are selected for design parameters for swirl-controlled effective factors dependent on journal speeds (3000, 9000, 15000, 21000 rpm). It has been found that the orifice diameter $d_0$ shows strong effects on effective maneuverability of direct-stiffness and direct damping values, while recess injection angle $\alpha$ results in substantial effects on the magnitude and direction of cross-stiffness. Specifically, recess injection parameters which are functions of angle of orifice feeding flow and recess dimensions showed very feasible effect on the stability control of swirl-controlled rotor-bearing system.

• International Journal of Fluid Machinery and Systems
• /
• v.5 no.2
• /
• pp.49-59
• /
• 2012

The present study is devoted to the influence of a superposed radial inflow in a rotor-stator cavity with a peripheral opening. The flow regime is turbulent, the two boundary layers being separated by a core region. An original theoretical solution is obtained for the core region, explaining the reason why a weak radial inflow has no major influence near the periphery of the cavity but strongly affects the flow behavior near the axis. The validity of the theory is tested with the help of a new set of experimental data including the radial and tangential mean velocity components, as well as three components of the Reynolds stress tensor measured by hot-wire anemometry. The theoretical results are also in good agreement with numerical results obtained with the Fluent code and experimental data from the literature.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.822-827
• /
• 2003

Experiments were done for the three dimensional unsteady flow in a counter rotating axial flow fan under stable operating condition. Flow fields in a counter rotating axial flow fan were measured at cross-sectional planes of the upstream and downstream of each rotor. Cross sectional flow patterns were investigated through the acquired data by the $45^{\circ}$ inclined hot-wire. Flow characteristics such as tip vortex, secondary flow and tip leakage flow were confirmed through axial, radial and tangential velocity vector plot. Swirl velocity, which was generated by the front rotor, was recovered in the form of static pressure rise by the rear rotor except for hub and tip regions.