An acoustic/thermal model for self-heating in PMN sonar projectors

Area of Science:

• Materials Science
• Acoustics
• Thermodynamics

Background:

• Electrostrictive ceramics like lead magnesium niobate (PMN) are used in sonar projectors.
• Dielectric hysteresis in PMN causes self-heating, impacting acoustic performance.
• Transducer temperature significantly influences sonar source level.

Purpose of the Study:

• To investigate the self-heating phenomenon in PMN flextensional sonar transducers.
• To develop a coupled electro-acoustic and thermal model for accurate performance prediction.
• To quantify the impact of temperature on PMN transducer acoustic output.

Main Methods:

• Developed an electro-acoustic model for a PMN flextensional transducer.
• Integrated a thermal finite element model to simulate heat transfer.
• Calculated source level and heat generation rate as functions of temperature.
• Validated the model against experimental data.

Main Results:

• Acoustic source level varied by 12 dB over a 75°C temperature range due to PMN's temperature dependence.
• The model predicted a steady-state equilibrium temperature where heat generation balanced heat dissipation.
• Despite temperature rise, PMN transducers outperformed lead zirconate titanate (PZT) transducers by 8 dB.

Conclusions:

• Accurate prediction of transducer temperature is essential for reliable sonar acoustic performance.
• The coupled modeling approach successfully captured the self-heating behavior and performance variations.
• PMN transducers offer superior acoustic output compared to PZT, even with self-heating effects.