Office National D'etudes Et De Recherches Aerospatiales

Jean-Claude Garnier

Alain A Deom

In a detection device of the presence of frost and/or measuring the thickness of the frost by ultrasound, a probe with a piezoelectric ultrasonic transducer generates an ultra-sonic acoustic emission wave and detects ultrasonic acoustic echo waves reflected by the frost. An actuating device for the probe is arranged to provide to the transducer electrical energizing signals. The probe comprises: a frost detector placed in front of the transducer and constituted of a material having an acoustic impedance between 30.times.10.sup.5 and 44.times.10.sup.5 kg m.sup.-2 s.sup.-1. This detector has a surface designed to be exposed to the surrounding atmosphere to be covered with frost. An acoustic delay device is adapted to ensure acoustic coupling and adaptation between the transducer and the detector and to separate in time the ultrasonic emission add reflected waves. A body of heat insulating material covers the assembly of the detector, the transducer and the acoustic delay device.

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Chatillon, France

Jean-Claude Garnier