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이현창 ( Hyunchang Lee ),차현우 ( Hyunwoo Cha ),강동현 ( Donghyeon Kang ) 한국분무공학회 2022 한국액체미립화학회지 Vol.27 No.1
Flash boiling occurs in a couple of modern engineering systems and understanding its mechanism is important. In this experimental study, discharge coefficient of flash boiling spray from simple orifice nozzle was measured, and backlight imaging was acquired at injection pressure to 6.0 bar and temperature to 163℃ for the purpose. Pressurized water by pump was used for working fluid and was heated by electric heater and ejected through simple orifice nozzle diameter of 0.5 mm. High speed camera with long distance microscope was used for backlight imaging in two FoV having magnification of 3.3 and 0.64. The decrease of discharge coefficient according to degree of superheating and evolution of flash boiling spray imaged at various pressure and temperature were explained by the pressure field inside the injector.
강동현(Donghyeon Kang),차현우(Hyunwoo Cha),이현창(Hyunchang Lee) 한국기계가공학회 2023 한국기계가공학회지 Vol.22 No.3
In this study, experimental equipment was designed and manufactured to realize flash boiling spray in scramjets, gas turbines, liquid rockets, and internal combustion engines. The injection pressure and temperature could reach up to 5 bar and 160 ℃, respectively, and the chamber pressure could be lowered to 0.03 bar. The heating capacity of the additional heater attached to the injector body was determined to be 330 W by considering heat transfer. The simple orifice nozzle (D: 0.5 ㎜, L: 4 ㎜, L/D: 8) was used and 9 cartridge heaters with a 300 W heating capacity were installed inside the chamber wall based on an ANSYS analysis to heat the vacuum chamber wall. Four visible windows (3 of 50 ㎜ × 160 ㎜, 1 of 110 ㎜ × 160 ㎜) were installed in the vacuum chamber to see inside the chamber. To obtain the flow discharge coefficient, a pressure sensor, and a volumetric flowmeter were used. By using this equipment, the spray shape and flow discharge coefficient was obtained at various injection pressures, temperatures, and atmospheric pressures. The preliminary result from the equipment is also shown.