Shape Determination of Aerosol Particles Using an Acoustic Transducer

Aerosol Particle Concentration Determined Using an Acoustic Transducer

“…Several unresolved issues, such as the mechanisms for acoustical signal generation, noted in references [3}6] were clari"ed and supported by the experimental data reported in references [1] and [2]. Based on the success reported in references [1] and [2], this study aims to answer the following questions: (1) what is the minimum detectable size with the current acoustical transducer?…”

“…Similarly, the higher the #ow rate is, the larger the signal amplitude becomes for a given particle size, as the amplitude of the disturbance increases with the #ow velocity for a given particle size [1]. An attempt to determine the aspect ratio of graphite "bers, which should help to determine particle shapes [2], proved successful.…”

“…Larger particles therefore give away signals with larger amplitudes and are easier to detect [1]. Spherical particles with diameters signi"cantly less than 5)9 m were di$cult to detect, while graphite "bers with a diameter of 7)3 m and various lengths were detectable [2]. Similarly, the higher the #ow rate is, the larger the signal amplitude becomes for a given particle size, as the amplitude of the disturbance increases with the #ow velocity for a given particle size [1].…”

“…The current acoustic transducer involves no lasers and requires little power, as the air#ow rate drawn through is no more than a few liters per minute. Relevant "ndings for the transducer [1,2] are outlined below.…”

“…The inlet tube was joined by a capillary tube (1)98 mm in diameter) with a contraction. Particles tested included polystyrene latex (PSL) spheres [1] and graphite "bers with a diameter of 7)3 m and length ranging from 1)59 to 25)4 mm (i.e., the aspect ratio equal to 218}3480 [2]). It was found that the inlet tube behaved like an organ pipe with one open end.…”