N211-077 TITLE: Non-towed Broadband Acoustic Source
RT&L FOCUS AREA(S): Autonomy
TECHNOLOGY AREA(S): Battlespace Environments
OBJECTIVE: Develop an innovative, acoustic source for operation from an 11-m unmanned surface vehicle (USV) producing the required output.
DESCRIPTION: Unmanned surface vehicle (USV) -based systems require lighter weight, lower drag, and smaller footprint products than their legacy counterparts [Ref 1]. There are currently a number of technology development efforts for various types of sensors and emitters that will be suitable for integration with a Fleet-class (11-meter) USV. However, many of these sensors and emitters are towed systems, which result in increased drag and fuel consumption, as well as reduced capability in shallow water and constrained waterways [Ref 2]. By eliminating the towed system from the USV, a reduction in towed system drag on the craft will result in increased endurance for the system while operating at the same speed. This will increase system capability by potentially increasing the coverage rate and allowing its use in shallower water and constrained waterways than current towed systems.
The U.S. Navy is seeking an innovative acoustic source capable of generating a broad range of outputs that would be mounted either above the waterline, within the hull and structure of the USV, or if a solution were sub-surface, the acoustic generator would be stowed above the waterline or within the USV hull-form until performing operations. The acoustic source(s) will be capable of being operated in very shallow water (20-40 ft), have low/no-drag (drag is constrained by the propulsive power used), and be non-towed or easily deployed/retrieved from the USV (less than 10 below the keel of the vehicle). Use of USV propulsion and hull systems, as well as legacy methods (e.g., mechanical cavitation, spark gap) is encouraged. The system must be lightweight (less than 400 lb.); require minimal electrical or propulsion power (less than 30 kw electrical power; Propulsive Power 125 hp); have a high acoustical power radiation (minimum 175 dB re 1 �Pa @ 1m (1/3 Octave Band Level), frequency range of 10 Hz to 32 kHz, broadband white noise or multiple tones distributed over the required bandwidth, omni-directional or forward hemisphere transmission from one or several generators); and mitigate the effects of craft speed and its variations (12-18 kts, �5 kt speed variation). The acoustic generator will be autonomously activated by the USV�s central command and control.
Offerors are encouraged to propose concepts that use waste energy from the USV (e.g., exhaust, propulsion noise, flow) that is amplified, controlled, and manipulated by the concept to generate the desired output. Legacy concepts (e.g., mechanical cavitation, spark gap) are also encouraged. Sets of transducers may not be viewed as novel technology for this topic unless of a new form or application, or offering unique capabilities in the operating environment is articulated. Offerors should note the likely presence of cavitation in the operation of their system and, if relevant, should address in their proposals how the system mitigates its effects, or uses it to a beneficial effect.
By eliminating towed items, the towed system drag to the Unmanned Surface Vehicle (USV) can be reduced by up to 50%. That savings will result in a lower fuel burn rate and an increased endurance. An increase in endurance will increase the capability of the USV and multiple payloads can be carried on the USV for multiple mission sets. Dragging these systems through the seawater increase the life-cycle cost based on the maintenance associated with the seawater environment. By removing the acoustic source from the water, the mean time before maintenance will increase which will reduce the life-cycle cost of these systems.
PHASE I: Develop a concept for an acoustic generator meeting the requirements in the Description. Feasibility of the concept for an innovative acoustic generator that meets the needs of the Navy as defined in the Description will be demonstrated by modeling and simulation, analysis, and/or laboratory experimentation, as appropriate. Acoustic output (frequency range, amplitude) will be the key quantitative performance parameter, with the level of speed independence, and size/weight/power being key system attributes. The effect of cavitation on the system performance, if relevant, should be clearly presented through the concept development and feasibility demonstration. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.
PHASE II: Develop and fabricate a prototype acoustic generator based on the Phase I work and Phase II Statement of Work (SOW) for demonstration and characterization of key performance parameters, key system attributes, and objectives. At the end of Phase II, prototype acoustic generator components shall be tested according to Navy requirements. Testing of the key performance parameters and key system attributes will be an at-sea test over an acoustic range to verify that the task objectives were met. Based on lessons learned in Phase II through the prototype demonstration, a substantially complete design of the acoustic generator should be completed and delivered that would be expected to pass Navy qualification testing.
PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the technology for Navy use. The final acoustic generator product will need to conform to all specifications and requirements. A full-scale prototype will be operationally tested at sea on an acoustic range and certified by the Navy to be integrated with an USV for further performance testing.
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KEYWORDS: Non-towed acoustic generator; unmanned surface vehicle (USV); acoustic frequency and amplitude; autonomous