Aeronautics and astronautics – Aircraft – steering propulsion – Fluid
Reexamination Certificate
1998-06-24
2001-06-26
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft, steering propulsion
Fluid
C244S07300B, C244S012500, C060S230000
Reexamination Certificate
active
06250586
ABSTRACT:
The present invention relates to apparatus and also to a method for controlling the motion of a solid or a fluid stream. As will be described more particularly below, the apparatus and method of the invention may be used to generate forces and moments on the moving medium in order to alter trajectory. The invention may also be used to effect thrust control, e.g., to augment thrust, of a self-propelled solid body.
U.S. Pat. No. 4,260,204, a joint inventor in which is also a joint inventor in the present application and which is hereby incorporated by reference, discloses a method and apparatus for enhancing the mixing of two fluids by providing flow perturbations near the origin of the mixing region about an axis substantially normal to the prevailing flow direction. Examples of possible uses of the technique described in that patent include promoting combustion in jet engines, suppressing audible jet noise, and increasing output of ejector pumps.
U.S. Pat. No. 5,244,203, the inventor in which is a joint inventor in the present application and the disclosure of which is also hereby incorporated by reference, discloses a method and apparatus for exploiting the technique of U.S. Pat. No. 4,257,224 to delay the separation of a boundary layer of a fluid flowing over a solid surface. Disclosed applications of the technique described in U.S. Pat. No. 5,209,438 include increasing the lift of a wing, while decreasing its drag, and also increasing the divergence angle of a diffuser.
The present application is directed to still other methods and apparatus for exploiting the mixing technique described in U.S. Pat. No. 4,257,224, particularly for controlling the motion of a solid body or of a fluid stream.
According to one aspect of the present invention, there is provided, in a fluid dynamic system including a fluid medium separated from a solid medium by a solid boundary, one of which media is moving with respect to the other, apparatus for controlling the motion of the moving medium, comprising: a perturbation-producing element at the solid boundary; and a drive for cyclically driving the perturbation-producing element to produce cyclical fluid perturbations in the fluid medium sufficient to alter the motion of the moving medium.
In some described embodiments, the moving medium is a solid body (the solid medium) which includes a combustion chamber having an exit nozzle through which a fluid jet is discharged, the cyclical fluid perturbations being generated at selected locations on the exit nozzle around its longitudinal axis to alter the motion of the solid body. Examples of this application of the method would include the control of the movements of solid bodies, such as aircraft, rockets, etc., moving through the air or space, and sea vessels moving through the water, and the like.
The invention may also be used to control the motion of a fluid medium with respect to solid boundaries, for example in order to divert the fluid stream or a part thereof to another path. Examples of this application of the method would include controlling the inlet flow, or internal flows in general, of a fluid medium used for cooling, combustion, or the like.
It will be appreciated that in most of the described embodiments the control can be effected continuously, by subdividing an actuator generating the perturbations into short segments, and by controlling the frequency and/or amplitude of the perturbations emanating from each segment. It is contemplated, however, that in some applications the control can be effected in an “on/off” manner.
According to a further aspect of the invention, there is provided apparatus for spreading the jet emanating from the entrance region of a short, wide angle nozzle providing efficient thrust recovery and thrust vectoring, the apparatus including cyclically driven perturbation-producing elements which generate periodic perturbations within the fluid, which perturbations are varied around the periphery of the nozzle to deflect the entire stream from its original direction thus achieving thrust vectoring, the jet deflection being proportional to the frequency and strength of the periodic perturbations.
The invention also provides a method for controlling the movement of a solid body or a fluid stream, in accordance with the foregoing apparatus.
Further features and advantages of the invention will be apparent from the description below.
REFERENCES:
patent: 3299638 (1967-01-01), Santamaria et al.
patent: 3786993 (1974-01-01), Burgess et al.
patent: 4754927 (1988-07-01), Fitzgerald
patent: 5154050 (1992-10-01), Herup et al.
patent: 5706650 (1998-01-01), Thayer
Seifert Avi
Wygnanski Israel
Eldred J. Woodrow
Friedman Mark M.
Ramot University Authority for Applied Research and Industrial D
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