Matching a Transducer to Water at Cavitation: Acoustic Horn Design Principles

  • Shows why conventional ultrasonic horns cannot be scaled up without sacrificing high ultrasonic amplitudes;
  • Describes novel design principles that allow horn diameters and their amplitude gain factors to be independent variables;
  • Introduces Barbell horns, which can simultaneously have large output diameters and provide high ultrasonic amplitudes.

Sergei L. Peshkovsky, Alexey S. Peshkovsky, Matching a transducer to water at cavitation: Acoustic horn design principles, Volume 14, March 2007, Pages 314–322.

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High-power ultrasound for several decades has been an integral part of many industrial processes conducted in aqueous solutions. Maximizing the transfer efficiency of the acoustic energy between electromechanical transducers and water at cavitation is crucial when designing industrial ultrasonic reactors with large active volumes. This can be achieved by matching the acoustic impedances of transducers to water at cavitation using appropriately designed ultrasonic horns. In the present work, a set of criteria characterizing the matching capabilities of ultrasonic horns is developed. It is shown that none of the commonly used tapered-shape horns can achieve the necessary conditions. An analytical method for designing five-element acoustic horns with the desirable matching properties is introduced, and five novel types of such horns, most suitable for practical applications, are proposed. An evaluation of the horns’ performance is presented in a set of experiments, demonstrating the validity of the developed theoretical methodology. Power transfer efficiency increase by almost an order of magnitude is shown to be possible with the presented horn designs, as compared to those traditionally utilized.