Ultrasonic aircraft ice detector using flexural waves
First Claim
1. A system for detecting the presence of ice and water on a thin-walled surface comprising:
- means for generating a signal;
a transmitting transducer producing an acoustic signal according to said generated signal;
means for coupling said acoustic signal to said thin-walled surface providing acoustic signal propagation thereon in at least two modes;
a receiver transducer providing an electrical signal corresponding to a received acoustic signal;
means for coupling said receiver transducer to said thin-walled surface, coupling the propagated acoustic signal to said receiver transducer;
receiver means providing a first and a second signal, each signal corresponding to a different mode of propagation of said acoustic signal;
means for providing a signal corresponding to a ratio between the amplitudes of said first and said second signal; and
indicator means for providing an alarm signal when the signal provided by said ratio signal means exceeds a predetermined threshold indicating the presence of one of ice and water on said thin-walled surface.
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Accused Products
Abstract
A system for the detection of wing icing by monitoring variations in flexural waves transmitted through the outer plate material of an aircraft airfoil. The flexural waves in the plate of the wing airfoil are more subject to variation from the accumulation of ice on the wing than the compressional waves. The flexural waves are detected apart from the compressional waves, which tend to remain relatively constant, to provide an indication of icing. Changes in amplitude, phase or dispersion characteristics of the flexural waves are detected to indicate ice buildup, and, in one embodiment, these values are ratioed to the corresponding levels in the compressional wave in order to provide compensation for variations other than ice buildup. The ultrasonic waves may be coupled directly from a transducer to the airfoil plate or via an ultrasonic waveguide interposed between the transducer and the plate. The receiver for the ultrasonic waves to be detected may be positioned to receive direct flexural waves transmitted over a distance through the plate or flexural waves reflected from reflecting boundaries in the plate.
68 Citations
21 Claims
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1. A system for detecting the presence of ice and water on a thin-walled surface comprising:
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means for generating a signal; a transmitting transducer producing an acoustic signal according to said generated signal; means for coupling said acoustic signal to said thin-walled surface providing acoustic signal propagation thereon in at least two modes; a receiver transducer providing an electrical signal corresponding to a received acoustic signal; means for coupling said receiver transducer to said thin-walled surface, coupling the propagated acoustic signal to said receiver transducer; receiver means providing a first and a second signal, each signal corresponding to a different mode of propagation of said acoustic signal; means for providing a signal corresponding to a ratio between the amplitudes of said first and said second signal; and indicator means for providing an alarm signal when the signal provided by said ratio signal means exceeds a predetermined threshold indicating the presence of one of ice and water on said thin-walled surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of detecting the presence of ice and water on a thin-walled surface circuit, comprising the steps of:
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applying sound energy to said thin-walled surface; sensing the propagation of the sound energy over a distance on said thin-walled surface and providing a corresponding sensed signal; separating said sensed signal into a first and second signal, each said signal corresponding to a different wave propagation mode; determining the ratio between the amplitudes of said first and second signal and providing a ratio output signal; and indicating the presence of a loading condition according to the relative amplitude of said ratio output signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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Specification