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Microbubble Drag Reduction Demonstration Primary Sponsor: Department of Defense Deadline: 4/11/2001 KEYWORDS TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes DOD ACQUISITION PROGRAM SUPPORTING THIS TOPIC: FNC: Expeditionary Logistics OBJECTIVE: An intermediate to large scale sea-borne implementation of microbubble drag reduction (MBDR) is desired to determine scale-up and seawater effects on the efficacy of the technique, as well as on bubble and ejection parameters, and robustness in at-sea conditions. DESCRIPTION: The injection of microbubbles into a turbulent boundary layer has been demonstrated to reduce frictional drag up to 80% in laboratory scale tests. Though the speeds of the tests have been as high as 50 knots, the models were small, and the tests were conducted in fresh water. As scale is increased to that of sea-going vessels, the usefulness of the technique is unknown. It is desirable to perform tests of MBDR on larger sea-going platforms at speeds sufficiently high to approach or exceed a Reynolds number of 2x10^8. A length of at least 10 meters is desired. Hydrofoil and SWATH configurations would be particularly attractive since friction is the predominant drag contribution in those cases. Measurements of flow and microbubble variables at these larger scales are needed to establish a knowledge-base sufficient for design. PHASE I: A laboratory demonstration of a microbubble injection technique based on present knowledge and scaled up for a sea-borne platform implementation will be required. A platform will need to be identified, and a detailed design of the at-sea test system will need to be completed, including alterations to the platform. Instrumentation will need to be designed or selected to measure the expected drag reduction and MBDR parameters with adequate resolution and accuracy as exhibited in an uncertainty analysis. PHASE II: At-sea trials on the selected platform will be conducted to determine the performance of the MBDR system. Bubble injection parameters and platform operation, such as speed, turns, seastate, etc., will be varied to develop a database of performance. Measurements of drag reduction and other variables, such as air flowrate, plenum pressure, and bubble distribution, will be performed. A total system energy balance, including air pumping will be performed. PHASE III: Both the Navy and the commercial sector are expected to be highly interested in this technique if found to be feasible at ship scale because of increasing interest in the reduction of fuel consumption. Existing and near future hydrofoil, SWATH, and similar configurations would be expected to be the initial target of application since frictional drag is relatively more important for these configurations. Future larger sealift ships of similar design are also envisioned. DUAL-USE POTENTIAL: The growing market for high-speed ferries would be the prime initial commercial target for MBDR application. Many of these utilize configurations which could benefit from a successful application of drag reduction. Larger ships would benefit eventually if the technology proves to be useful and adaptable to more conventional hull-forms. REFERENCES: (1) Madavan, M.K., Deutsch, S. and Merkle, C.L, "Measurements of local skin friction in a microbubble-modified turbulent boundary layer," J. Fluid Mech. V.156, 1985. (2) Deutsch, S., and Castano, J., "Microbubble skin friction reduction on an axisymmetric body", PSU/ARL-TM-85-139 , available in DTIC as ADA247709, www.dtic.mil. (3) Marie, J.L., "A simple analytical formulation for microbubble drag reduction", Physicochemical Hydrodynamics V.8 no.2, 1987. KEYWORDS: Microbubble; Drag Reduction; Ship; Hydrofoil; SWATH; Demonstration DoD Notice: Between January 2 and February 28, 2001, you may talk directly with the DoD scientists and engineers who authored the solicitation topics, to ask technical questions about the topics. The Topic Author is listed in the box below. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed after February 28, 2001, when DoD begins accepting proposals under this solicitation. TPOC: L. Patrick Purtell Phone: 703-696-4308 Fax: 703-696-2558 Email: purtelp@onr.navy.mil. 2nd TPOC: G. Kevin Comer Phone: 703-696-5354 Fax: 703-696-2558 Email: comerg@onr.navy.mil. After February 28, 2001 proposers may still submit written questions about solicitation topics through the SBIR/STTR Interactive Topic Information System (SITIS). If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at (800) 382-4634 or email to SBIRHELP@teltech.com. NOTE: The Solicitations listed on this site are copies from the various SBIR agency solicitations and are not necessarily the latest and most up-to-date. For this reason, you should use the agency link listed below which will take you directly to the appropriate agency server where you can read the official version of this solicitation and download the appropriate forms and rules. The official link for this solicitation is: http://www.acq.osd.mil/sadbu/sbir/sttr01/dod_sttr01.htm. DoD will begin accepting proposals on March 1, 2001. The solicitation closing date is April 11, 2001.