SBIR-STTR Award

The Research and Development effort proposed by Hydroacoustics Inc (HAI) will determine the feasibility of applying new technologies to a Very Low Frequency (VLF) transducer design thereby extending its performance to meet the new requirements of Acoustic Augmentation Support Program (AASP). These new technologies include, but are not limited to, developing a the largest transducer consistent with the installation space, exploring material alternatives for the VLF transducer, reviewing new hydraulic valve technologies, seeking more effective means to couple the hydraulic power to the acoustic medium, studying pump and motor designs to reduce the noise generated by the hydraulic power supply while in the stand-by mode, and applying new digital electronics to monitor and control the transducer performance. The HAI math model for the HLF transducer will be used to estimate the performance of the new VLF transducer design, and the historical HAI data will be used to estimate the manufacturing time and cost.

Benefit:
The basic benefits of the HAI VLF will be maintained while applying the new technologies to its design. Since opposing flexing disk radiators of the HAI VLF eliminate the inertial mass needed by a single-ended transducer design, the force balanced acoustic transducer configuration will be used. The basic shape of this transducer configuration is an effective pressure vessel which eliminates the need for pressure compensation at submarine depths. The power amplifier will be located within the transducer which eliminates the need for large power amplifiers on the submarine and requires only raw power and a low-level drive signal to pass through the hull. The transducer will be robust with high reliability as has been demonstrated by the many years of service and by passing Level B shock tests. These benefits will be enhanced by extending the performance to a lower frequency, by reducing the radiated noise while in the stand-by mode, and by reducing the cost and time for manufacture and service. Since the underlying technology of the current VLA is proven and well understood, these enhancements will be available to the U.S. Navy quickly, without a prolonged development and testing cycle. As a result, the Navy will have a more effective and cost efficient VLF transducer for the AASP available to for use in the fleet in a short period of time.

Keywords:
AASP, AASP, Submarine, VLF underwater transducer, VLF transducer, Low frequency high power underwater transducer, acoustic augmentation, Noise augmentation

The proposed Research and Development effort will transition the technology advances identified during the trade-space studies in Phase I of this SBIR into an Engineering Development Model (EDM) of the new AASP VLF (the HAI HLF-1F transducer). These advances provide a transducer with an acoustic output of at least 150 dB re 1 uPa @ 1 m from 10 to 1,000 Hertz, no appreciable acoustic output in the stand-by condition, and a reduced total ownership cost. The EDM design of the HLF-1F will evolve from the proven design and technology of the HAI HLF-1D and HLF-1E transducers by combining important features of the two current AASP transducer with the technological advances identified in Phase I. The initial integrated design of the HLF-1F transducer will be reviewed with the SBIR TPOC during a Preliminary Design Review, and the initial piece-part drawings and purchased components will be reviewed during a Critical Design Review. After approval of the design, the EDM of the HLF-1F transducer will be built and tested and a Final Design Review will be conducted with the TPOC. If the Phase II Option is executed, any changes identified during the Phase II Final Design Review will be incorporated into the initial EDM design, modified parts will be procured, and a modified EDM of the HLF-1F transducer will be built and tested.

Benefit:
The anticipated benefits to the U.S. Navy will be the immediate availability of an improved AASP VLF transducer suitable for deployment in the TRIDENT, SEAWOLF, and VIRGINIA submarine classes with little or no additional cost, time, or testing. Minor changes to the transducer mounting hardware may be needed, but no modifications to the AASP sea chest or to the hull penetrators will be required. It is anticipated that the new HLF-1F transducer can be used, with no modifications, in the OHIO class replacement submarine. Other U.S. Navy programs in anti-submarine warfare, wide area ocean surveillance, acoustic communications, military deception, underwater tomography, and ocean science exercises would also benefit from the technological advances in Phase II of this SBIR. If the new HAI VLF transducer were installed in a simple tow body similar to those used for other transducers in the HLF family, it could be towed by research vessels for strategic and tactical surface ship applications as well as for underwater research projects. The technology advances from this SBIR will have commercial applications in addition to the military applications identified above. These include low frequency sources for the U.S. Coast Guard to use in port and harbor security applications, for enhanced oil recovery applications, for protection of aquaculture facilities from damage by seals and sea lions, for studies of the effects of sound on marine life, and for low frequency augmentation of ocean observatories. The most immediate commercial application of this SBIR is low frequency marine seismic exploration. The improved low frequency performance of the AASP VLF transducer can be applied directly to marine seismic surveys to improve the detection of oil deposits deep below the ocean bottom. Such low frequency acoustic capability has not been exploited for marine seismic exploration.

Keywords:
AASP, Acoustic Augmentation System Program, low frequency transducer, High Source Level, Submarine, hydraulic, hydroacoustics