Abstract:

Measurements of macrosonic standing waves in oscillating closed cavities are shown. These cavities (resonators) were designed by MacroSonix using resonant macrosonic synthesis (RMS) to shape the resultant waveform. By controlling the nonlinear processes by which energy is transferred to harmonic frequencies, RMS allows design of resonators that give high-amplitude shock-free waveforms. Measurements in cavities designed with RMS show standing-wave overpressures in excess of 340% of ambient pressure, compared to maximum overpressures in cylindrical cavities of about 17%. Power is delivered by oscillating the entire resonator along its axis with a linear actuator (entire resonator drive). Measurements are shown for four axisymmetric resonator shapes: cylinder, cone, horn-cone hybrid, and bulb. Resonators were filled with nitrogen, propane, or refrigerant R-134a (1,1,1,2-tetrafluoroethane). Ratios of peak-to-minimum pressures of 27 were observed. Since practical compressors for air, refrigerants, or other gases require pressure ratios (discharge to suction) of 3 or more, RMS technology can be used in a wide range of applications. Frequency sweeps show softening or hardening behavior, depending on resonator shape. High-amplitude resonance sweeps show significant hysteresis.