Abstract
In this paper, small-sized acoustic horns, the sensitivity enhancement package for the MEMS-based thermal acoustic particle velocity sensor, have been designed and optimized. Four kinds of acoustic horns, including tube horn, double cone horn, double paradox horn, and exponential horn, were analyzed through numerical calculation. Considering both the amplification factor and effective length of amplification zone, a small-sized double cone horn with middle tube is designed and further optimized. A three-wire thermal acoustic particle velocity sensor was fabricated and packaged in the 3D printed double cone tube (DCT) horn. Experiment results show that an amplification factor of 6.63 at 600 Hz and 6.93 at 1 kHz was achieved. A good 8-shape directivity pattern was also obtained for the optimized DCT horn with the lateral inhibition ratio of 50.3 dB. No additional noise was introduced, demonstrating the DCT horn’s potential in improving the sensitivity of acoustic particle velocity sensors.
Highlights
Sound signal is one of the most common forms of signals in nature
The direction of sound propagation can be obtained by measuring the direction of acoustic particle velocity
thermal acoustic particle velocity sensor (TAPVS) shows promising properties for applications in sound source localization [7,8,9,10,11,12,13], such as engine fault detection [14,15,16,17], gunshot localization [18,19], and pipe leakage acoustic detection [7,20] etc., which is far superior to microphone arrays for its higher orientation accuracy, smaller size, simpler signal processing [21], wider working temperature range [22], lower low frequency self-noise [4,23], and so on
Summary
Sound signal is one of the most common forms of signals in nature. To fully define a sound signal at a single point, at least two parameters are required, a scalar of acoustic pressure and a vector of acoustic particle velocity [1]. As for MEMS-based TAPVS, acoustic horns should be scaled down to a smaller size, where the boundary layer effect is no longer neglectable and the assumptions of the Webster’s horn equation may be invalid. To address this problem, a correction model for the small-sized double cone (DC) horn with. Sensors 2021, 21, 4337 the consideration of the boundary layer effect was proposed and experimentally verified in our previous work [36], which can give more accurate velocity gain amplification factors at the narrow horn throat than the traditional DC horn model [33]. Hfroeqwueevnecry, rfaonrgtehefosrmthaelll-asrigzee-dsizheodrnh,oarns sahnodwthnatinthFeigvuisrceos2ibty, igsrneaegtelercptaabrlteic. le velHocoiwtyegvaeri,nfsoar rteheosbmsearlvl-esdizeedspheocrina,llays isnhothwenloinwFifgreuqreue2bn,cgyrreantegrepwarhtiecnletvheelomcietydiguaminsviscosiatyreisobtasekrevnedinetsopceocinaslilydeinratthioenlo. wThfererqeuaesnocnyirsatnhgaetwthheensiztheeomf tehdeiuhmorvnisacnodsittyhies tthaikceknness of vinistcoocuosnsbioduernadtiaorny. lTahyeerreaarseoniniscothmatptahreabsilzeesocfalteh,ewhhorenreanthdethbeouthnidckanryesslaoyfevriescffoeucst has a sbigounnifdicaarnytlainyeflruaernecien oconmthpearraebsluelstcsa. le, where the boundary layer effect has a significant influence on the results
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