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Amplitude and Wavelength Measurement of Sound Waves in Free Space using a Sound Wave Phase Meter
함성길,이기원 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.9
We developed a sound wave phase meter (SWPM) and measured the amplitude and wavelength of sound waves in free space. The SWPM consists of two parallel metal plates, where the front plate was operated as a diaphragm. An aluminum perforated plate was additionally installed in front of the diaphragm, and the same signal as that applied to the sound source was applied to the perforated plate. The SWPM measures both the sound wave signal due to the diaphragm vibration and the induction signal due to the electric field of the aluminum perforated plate. Therefore, the two measurement signals interfere with each other due to the phase difference according to the distance between the sound source and the SWPM, and the amplitude of the composite signal that is output as a result is periodically changed. We obtained the wavelength of the sound wave from this periodic amplitude change measured in the free space and compared it with the theoretically calculated values.
이택상,함성길,박종호,이성노 忠南大學校 産業技術硏究所 2002 산업기술연구논문집 Vol.17 No.2
The supersonic impinging jets are observed when exhaust gases from missiles or V/STOL aircrafts impinge on the ground, flame defector, ship deck, etc. The flow shows different patterns according to the nozzle geometry, nozzle-to-cone distance. This paper describes experimental works on the phenomena when underxpanded jets impinge on the cone-type deflector. The variety of flow parameter involving underexpansion ratio, nozzle to wedge apex spacing are considered.