Initial Experimental Evaluation of a Circulation Controlled Sail on a Submersible Vehicle for Enhanced Maneuverability
Technical rept. May 2005-Sep 2006
NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
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The potential for the sail bridge fairwater of a submerged vehicle to serve as an on-demand auxiliary maneuvering control surface was experimentally investigated in a wind tunnel. The sail used circulation lift control in the form of mass ejection from Coanda-effect trailing edge region slots. The sail was mounted on, and tested in conjunction with, an exploratory submarine hull design. Test results show that the side force developed by circulation control equaled the side force produced by yawing the fully appended hull by 10 deg, a substantial turning diameter reduction effect. This benefit was present over the tested yaw angle range of 30 deg. Associated yaw moments are in the favorable direction of turning the hull into the turn. Roll moment increments were lower than expected due to a counter-roll effect produced by the pressure field acting on the relatively flat hull topside. For side force and yaw moment, the data indicated that the body-sail interaction effects were negligible at zero angle of hull pitch and yaw no crossflow. For a 10-deg noseup pitch at zero drift angle, the body reacted to sail circulation by developing an in-plane side force equal to that produced by the circulation of the sail conversely, at 10 deg nosedown, the body contribution reversed direction so that the net side force was one-half of that at zero pitch. Out-of-plane forces at angles of drift yaw were generally not adversely impacted by sail lift augmentation, for a given level of net vehicle side force. Slot flow rate requirements for various operational conditions, and near-term development plans, are discussed. With the successful outcome of this demonstration of a lift augmented sail, it is recommended that systematic maneuvering simulations be conducted to quantify the specific benefits of a circulation controlled sail on naval vessels of interest.
- Submarine Engineering
- Electricity and Magnetism