| 摘要 |
<p>A transducer member (22) is made from a piezoelectric material (e.g. barium titanium) having a looped configuration and a gap (26) in the loop and having properties of vibrating upon the introduction of an electrical voltage to the transducer member (22). A support member (24) made from steel or aluminum and having (a) a looped configuration and enveloping, and attached to, the transducer member (229 has a gap (28) aligned with the transducer member gap (26) and has properties of vibrating with the transducer member (22). The transducer member (22) may have a uniform thickness around its periphery or a progressively increasing thickness with progressive distances from the gap (26). The transducer (20) has a high mechanical Q(e.g. 8-12) and a particular resonant frequency when disposed in air or in a vacuum. When the transducer (20) is disposed below the earth's surface, its resonant frequency may vary because of variations in the earth's characteristics at the different positions. An alternating voltage having the particular frequency as its fundamental frequency is applied to the transducer member (22) with a particular amplitude. The voltage has harmonics with large amplitudes (as in a square ware) relative to the particular amplitude. When the transducer member (22) is disposed in the earth, sound pressure waves are produced in the transducer (20) with larger amplitudes at harmonics and overtones of the fundamental frequency over a wide frequency range than the magnitude of the amplitude at the fundamental frequency. The harmonics and overtures produce an enhanced recovery of the oil from the earth regardless of the earth's variable characteristics.</p> |
