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Cavitating Flow in Rectangular Nozzle with Orifice
( Takao Inamura ),( Hidenori Saito ),( Masatoshi Daikoku ),( Takuro Onodera ),( Hiroshi Sakamoto ),( Akinaga Kumakawa ) 한국액체미립화학회 2005 한국액체미립화학회 학술강연회 논문집 Vol.2005 No.-
The experimental investigations of the cavitating flow in a rectangular nozzle with a orifice were conducted to make clear the relationship between a cavitating flow pattern and liquid injection conditions. The liquid injection pressure, chamber pressure were varied over the wide range. The cavitation number decreases as the Reynolds number increases. The effect of a jet Reynolds number on the cavitating flow pattern is small under the present experimental conditions. The magnitude of the acceleration of a nozzle is relating with the cavitating flow patterns. When the cavitating flow pattern changes from the smooth flow to the cloud and sheet cavitation flows, the root mean square value of the acceleration of a nozzle increases rapidly. And as the flow pattern changes from the cavitation flow to the hydraulic flow, the root mean square value decreases rapidly. These experimental results show that the cavitating flow pattern greatly affects the oscillation of a nozzle, that is the atomization instability. The reattachment of the liquid flow that detaches at the exit of an orifice makes the turbulences in the liquid flow. It is clear that these turbulences improve the atomization of a liquid jet issued from the nozzle exit.
Effectiveness Evaluation of View-Based Navigation for Obstacle Avoidance
Yoshinobu Hagiwara,Tetsunari Inamura,Yongwoon Choi 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
In this study, we propose an improved view-based navigation method for obstacle avoidance and evaluate the effectiveness of the proposed method in actual environments existing obstacles. The proposed method is able to estimate the position and the rotation of a mobile robot, even if the mobile robot strays from a recording path for avoiding obstacles. In order to achieve this, ego-motion was employed to the view-based navigation. The ego-motion is calculated from SURF points between a current view and a recorded view by using a Kinect sensor. In conventional view-based navigations, it is difficult to generate other paths to avoid obstacles. By using the proposed method, it is expected that a mobile robot plans flexible paths and avoids persons and objects in actual environments. From experiments performed in an indoor environment, we evaluated the measurement accuracy of the proposed method, and confirmed the feasibility of the proposed method for actual robot navigation.
Effect of Liquid Properties on Atomization Characteristics of Liquid Jet across Sheet-Like Air Flow
( T. Yamaguchi ),( T. Okabe ),( M. Shirota ),( T. Inamura ),( M. Daikoku ),( T. Soma ),( Y. Saito ),( Y. Matsushita ),( H. Aoki ),( J. Fukuno ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
A rotary bell-cup atomizer is widely used in the automotive spray painting. The characteristics of this painting is known as high quality finish, high coating efficiency and relatively homogeneous droplet production. The atomizer causes the ligament breakup by the shaping air blowing from the rear of the bell cup. The shaping air carries the generated droplets to the target. In the industrial painting, many paints of different physical properties are used. However, few studies have focused on the effects of physical properties of paint on the atomization characteristics such as the spray angle and the droplet trajectory. The objective of this study is to experimentally clarify the effect of the physical properties of paint on the atomization characteristics. In the experiment, liquid jet (assuming the ligament of paint) was broken up by sheet-like air flow. The experimental conditions such as the air velocity, the liquid density, viscosity and surface tension were varied. The droplet diameter and velocity were quantitatively measured by Particle Tracking Velocimetry (PTV) using double-pulsed Nd: YAG laser with a diffuser as a back light. The breakup point of the liquid jet was measured by image processing method. The experimental results showed that the decrease of surface tension and viscosity produces the finer droplets that are easily carried by the air flow, which results in the increases in the spray angle. This is because the decrease of restoring force and viscous damping due to the decrease of surface tension and liquid viscosity, respectively, promotes the deformation of liquid column, and increases the occurrence frequency of a bag-shaped breakup. We also revealed that the liquid viscosity and surface tension affect droplet trajectory and the range of spray angle.
Lattice modulation and superelasticity in oxygen-added β-Ti alloys
Tahara, M.,Kim, H.Y.,Inamura, T.,Hosoda, H.,Miyazaki, S. Elsevier Science 2011 ACTA MATERIALIA Vol.59 No.16
The microstructure and martensitic transformation behavior of (Ti-23Nb)-1.0O (at.%) alloy have been closely and systematically investigated by transmission electron microscopy (TEM). Diffuse streaks along the <110><SUB>β</SUB><SUP>*</SUP> directions with intensity maxima at ½ positions between basal spots are observed in selected area diffraction patterns obtained from the β phase. The streaks correspond to six variants of {110}<SUB>β</SUB><11@?0><SUB>β</SUB> transverse lattice modulation caused by randomly distributed oxygen atoms and their local strain fields. Nanosized modulated domains (nanodomains) in the β phase are confirmed in dark field micrographs. These nanodomains act as local barriers to martensitic transformation, thereby suppressing long-range martensitic transformation in the (Ti-23Nb)-1.0O alloy. We suggest a new mechanism for superelasticity in oxygen-containing β-Ti-Nb alloys based on the results of in situ X-ray diffraction measurements and in situ TEM observations.
Effect of Prefilmer Edge Thickness on Spray Characteristics in Prefilming Airblast Atomizer
( Naoki Katagata ),( Toshihiro Sakaki ),( Takahiro Okabe ),( Takao Inamura ),( Koji Fumoto ),( Minori Shirota ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
A prefilming airblast atomizer is a fuel injector used in aircraft gas turbines. The atomization mechanism of the atomizer is well known. After injection, the liquid homogeneously wets the prefilmer surface, and flows down to the prefilmer edge in the form of a liquid film that is sheared by the high-speed air stream. The accumulated liquid at the prefilmer edge is sheared by the air and disintegrated into the bag-shaped liquid framed by a thicker rim. The bag-shaped part of the structure bursts into fine droplets. The rim is stretched and fragments into two elongated ligaments that disintegrate into larger droplets than those generated by bag-shaped disintegration. We focused on the effect of the prefilmer edge thickness on the breakup phenomena of the liquid film and the spray characteristics. Our previous study showed that there is a correlation between the edge thickness and the breakup length and breakup frequency. The objective of this study is to clarify the effect of the prefilmer edge thickness on the spray characteristics such as the Sauter mean diameter (SMD) and the spray generation frequency. The SMD at three prefilmer edge thicknesses (160, 500, and 2000 ㎛) under various conditions were observed using a high-speed camera and an image processing technique. The measurement position from the prefilmer edge was widely varied. The fast Fourier transformation (FFT) analysis was also conducted to evaluate the periodicity of the SMD. The experimental results showed that the SMD increases as the prefilmer edge becomes thicker. In the wake region of the edge, the FFT analysis showed that the increase in prefilmer edge thickness causes the transition of the maximal power spectrum to a lower frequency (i.e. less than 100Hz) due to the larger volume of a liquid accumulation attaching to the edge.