Apparatus and method for aerodynamic blowing control using smart materials

#The present invention relates generally to the modification and control of flow around a body immersed in a fluid through the use of fluid jet blowing from openings (orifices or slots) on the surface of the body and to the use of smart material for controlling the characteristics of the blowing.

#The flow field around lifting surfaces, such as aircraft wings and helicopter rotor blades, determines the pressure distribution over these surfaces and, therefore, determines the resulting aerodynamic forces and moments acting upon such surfaces. The modification and control of those forces can thus be achieved through modification and control of the flow field.

#A number of methods of controlling the fluid flow around wings and rotors have been proposed and implemented. In the field of fixed wing aircraft, the most common method for controlling the flow around and consequently the forces generated by the wing is the use of a movable trailing edge surface, usually in the form of a flap. Basically, moving the trailing edge surface downward increases both the camber and the angle of attack of the wing thus modifying the flow field around the wing and causing the negative pressure distribution along the upper surface of the wing to increase in intensity. As a result, the lift force imparted to the aircraft is increased.

#FIG. 1 is a perspective illustration of a section of a section of a rotor blade or wing that embodies principles of the present invention in a preferred form.

#FIG. 2 is a sectional view taken along A--A of FIG. 1 illustrating one preferred smart material actuator based control mechanism for implementing the method of the present invention.

#FIGS. 3A, 3B, and 3C illustrate the present invention in another embodiment producing reduced turbulence and thus reduced losses within the passageway.

#Referring now to the drawing figures, in which like reference numerals designate like parts throughout the several views, FIGS. 1 and 2 illustrate one preferred apparatus and method for implementing the present invention. It should be noted that the embodiments illustrated and described herein make use of this invention as applied to a helicopter rotor blade. Further, the detailed description of the illustrated embodiment will also be presented in the context of a helicopter rotor blade. However, even though the invention is particularly suited to use with helicopter rotors, the scope of the invention is far from limited to such applications. It is equally applicable, for example, to the wings and control surfaces of fixed wing aircraft, to controlled blowing from fuselage sections of the aircraft and, indeed, to controlled fluid blowing from the control surfaces of submarines. It even has application in steering jets of air from nozzles and in vectoring the blowing of air from wings and rotors to form fluid flaps. Steering control for rockets and missiles is also an application as well as blowing control in general industrial applications such as spray painting and gas burners. Thus, it will be understood that the illustrated preferred embodiment is presented and discussed herein for ease and clarity of explanation, but that the invention is not limited in scope to the illustrated embodiment.

#One further point to be made is that the descriptions of the preferred embodiments that follow represents an accurate description of a proof-of-concept device, built within technological and financial constrains. As such, some of the features and design elements, although preferred and representative of the best mode presently known to the inventors, reflect the choices of material and processing techniques available at the stage of proof-of-concept. A commercial production system obviously would include additional elements required by mechanical constrains of an operating aircraft, however the basic principles disclosed and claimed herein would be embodied in a commercial system.

#FIG. 1 illustrates a short section of a helicopter rotor blade 12. It will be understood that the complete rotor blade is much longer than the illustrated section and normally extends from the hub of the helicopter to a distal end. The illustrated section is presented for clarity of presentation. A narrow slot 13 extends spanwise on the upper surface near the trailing edge portion of the blade. If the entire rotor blade were depicted, the slot 13 preferably would run spanwise for substantially the entire length of the rotor blade. As one skilled in the art will recognize, the length of the slot may be varied in accordance with the demands of a specific application. Furthermore, one skilled in the art will recognize that an elongated slot is not the only aperture configuration possible for use with the embodiments of FIGS. 1 and 2. For example, a plurality of small holes or a series of short slots could be used effectively. For this reason, the present invention is not intended to be, nor should it be, limited to only the use of a single, long slot in the surface of the blade.