Experimental Investigation of Asymmetric Spinnaker Aerodynamics Using Pressure and Sail Shape Measurements
Article dans une revue avec comité de lecture
An innovative method combining simultaneous on-water pressure and sail shape measurements for determining aerodynamic forces produced by sails is described and used on Stewart 34 and J80 Class yachts flying asymmetric spinnakers. Data were recorded in light and medium winds in order to check the reliability, accuracy and repeatability of the system. Results showed similar trends to the published literature. The accuracy of the system was investigated by wind tunnel tests, with determination of the entire sail shape from the stripe images recorded by the camera-based (VSPARS) system, and was found to be relatively good. Generally the pressure distributions show a leading edge suction peak, occurring at 5 to 10% of the chord length, followed by a pressure recovery and then a suction increase due to the sail curvature, with finally a reduction in suction near the trailing edge. The drive force coefficient measured on the Stewart 34 is lower than for the J80 because of a non-optimal sail shape due to light winds. On a reaching course, the standard deviation of the pressure signals was largest near the luff, reducing in the stream-wise direction, while it was high on the entire sail section when sailing on a running course.
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Communication avec acteDEPARDAY, Julien; BOT, Patrick; HAUVILLE, Frédéric; MOTTA, Dario; LE PELLEY, David; FLAY, Richard G.J. (2014)This work presents a full-scale experimental study on a sailing yacht in downwind conditions with simultaneous time-resolved measurements of pressures, sail shape and loads. Those on-water experiments on a J/80 class yacht ...
Communication avec acteDEPARDAY, Julien; BOT, Patrick; HAUVILLE, Frédéric; AUGIER, Benoit; RABAUD, Marc; MOTTA, Dario; LE PELLEY, David (2016)While sailing offwind, the trimmer typically adjusts the downwind sail "on the verge of luffing", letting occasionally the luff of the sail flapping. Due to the unsteadiness of the spinnaker itself, maintaining the luff ...
Article dans une revue avec comité de lectureDEPARDAY, Julien; BOT, Patrick; HAUVILLE, Frédéric; AUGIER, Benoit; RABAUD, Marc; MOTTA, Dario; LE PELLEY, David (The Society of Naval Architects and Marine Engineers, 2017)While sailing offwind, the trimmer typically adjusts the downwind sail “on the verge of luffing”, occasionally letting the luff of the sail flap. Due to the unsteadiness of the spinnaker itself, maintaining the luff on the ...
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Communication avec acteFLAY, Richard G.J.; PIARD, Arthur; BOT, Patrick (2017)While the aerodynamics of upwind sails are relatively well understood, flows past downwind sails are still very challenging. Indeed, downwind sails which can be considered as highly cambered thin wing profiles, are well ...