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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.
STUDY ON NEW ICE SLURRY GENERATOR USING NaCl AQUEOUS SOLUTION AT LOW CONCENTRATION
KOJI FUMOTO,TSUYOSHI KAWANAMI,TAKAO INAMURA 대한설비공학회 2013 International Journal Of Air-Conditioning and Refr Vol.21 No.1
A cold thermal energy storage system has been developed for HVAC. There are many ice-based cooling systems operating around the world. Ice slurry, which is a mixture of ¯ne ice crystals and liquid water, is utilized in ice storage systems owing to its good °owability and large latent heat of fusion. For slurry ice production techniques, there are presently a number of commercially available ice slurry generators (e.g., Supercooled slurry ice generator, Scraper type generator, and Vacuum type generator, etc.). In the present study, a new method was developed to generate ice slurry without the deposition of an ice layer on a cooled surface. The basic components of the experimental apparatus is a cooling brine circulating loop, a high pressure pump, a valve, an aqueous solution °ow loop containing the test section, which is made of transparent acrylic, and the associated instrumentation. This new method is based on freezing-point depression of the aqueous solution, which is maintained under high-pressure conditions. To control the timing for solidi¯cation and to generate ice slurry, we investigated the relationships among the pressure and temperature of the aqueous solution. The freezing phenomenon of the aqueous solution in the test section was observed in detail. As a result, we developed a new ice slurry generator based on the new method that controls the pressure and temperature of the aqueous solution. Experimental results showed that the characteristics of the ice slurry generation were closely related to the pressure and initial stage temperature of the test °uid. Finally, the optimum operation condition of the ice slurry generator based on visualization experiment was discussed.
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.