UACE2017 Proceedings: Low-frequency underwater pressure gradient receiver of force type

• Session:
  Vector Hydrophone Research
• Paper:
  Low-frequency underwater pressure gradient receiver of force type
• Author(s):
  Vladimir Korenbaum, Alexandr Tagilt?ev, Sergei Gorovoy, Anatoly Kostiv, Anton Shiryaev, Jury Fershalov
• Abstract:
  The usage of vector-scalar sensors, consisting of a pressure gradient receivers (PGR) and sound pressure receivers (PR) is considered promising for spatial selectivity and improving noise immunity of point and linear hydroacoustic antennas. However, designing PGR for low-frequency band is associated with a number of technical problems (qualitative dipole directivity, sufficient sensitivity to sound pressure, acceptable size). Four schemes of PGR construction are well-known, while only inertial-type and force-type schemes are applicable for low-frequency range. An original device of 2-component force-type PGR is designed in which round bimorph flexural sensors are set in tandem in the cylindrical housing made from sound isolator material. This housing has inner channels of specific configuration, which ensures the identity of a phase center for both PGR components. The mathematical model is constructed to evaluate approximately PGR sensitivity to sound pressure in flat wave, as well as to optimize sizes of inner channels in the housing. The laboratory prototype with dimensions of 111 × Ø52 mm is manufactured. Its sensitivity to sound pressure is experimentally measured in an oscillating column of liquid for frequency range of 63-140 Hz. The frequency dependence of experimental sensitivity, taking into account standard deviation of measurements, is close to theoretically predicted frequency slope of PGR response (6 dB/octave). Experimental values of sensitivity are close to theoretically predicted too. At the frequency of 100 Hz theoretically predicted sensitivity is 70 ?V/Pa, while measured value is 60 ?V/Pa (without additional amplification). Experimentally measured depth of minimums of dipole directivity pattern of PGR components is not less than 20 dB over frequency range of 63-140 Hz. A 2-4 fold excess of sensitivity above known force-type PGRs of the same diameter is reached.
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Contact details

• Contact person:
  Prof Vladimir Korenbaum
• e-mail:
  
• Affiliation:
  Pacific Oceanologic Institute of Russian academy of sciences
• Country:
  Russian Federation