Abstract: The invention relates to an ultrasonic tomograph for spatial and temporal characterisation of fluids in motion such as air and water. This tomograph comprises a plurality of pairs of emitting-receiving ultrasonic probes, whereas each pair may be inscribed, diametrally opposite, on a circle centred round a flow axis of the fluid. The probes are therefore laid out on either side of the flow and will neither modify nor disturb the flow. Each probe may be displaced in a plane perpendicular to the flow axis. Indeed each probe is allocated a stepping motor. Each probe is a piezoelectric ceramic transducer which does not drift with time and which does not require any re-calibration, which provides the tomograph according to the invention stability over time. Moreover this tomograph is robust since these ultrasonic probes may be used under extreme conditions. The frequency of ultrasounds ranges between 30 kHz and 300 kHz.

Abstract: The invention concerns an ultrasonic tomograph for spatial and temporal characterisation of moving fluids such as air and water. Said tomograph comprises a plurality of pairs of ultrasonic transceiver probes, each pair capable of being oppositely inscribed on a circle around a fluid line of flow. The probes are therefore arranged on either side of the flow and neither modify nor disturb it. Each probe is capable of moving on a plane perpendicular to the line of flow. Indeed each probe is associated with a step motor. Each probe is a piezoelectric ceramic traducer which does not suffer any drift in time and which does not require re-calibration, which provides the inventive tomograph with temporal stability. Moreover, said tomograph is robust since said ultrasonic probes can be used in extreme conditions. The frequency of the ultasounds range between 30 kHz and 300 kHz.

Abstract: An ultrasonic viscometer is described which is particularly designed for monitoring the viscosity of a thermally curing resin or composite, such as a fiber-reinforced epoxy composite, in an autoclave at high temperature. According to a preferred embodiment, the viscometer comprises a piezoelectric element of lithium niobate crystals bonded to a first buffer of copper, which is bonded on the other side to a second buffer of aluminum. The resin or composite is in contact with the second buffer. When the transducer emits a short ultrasonic pulse, two echoes are reflected back, the first echo being generated by the copper-aluminum interface, the second by the aluminum-resin interface. The signals from the two echoes are processed to obtain the complex reflection coefficient at the interface of the second buffer and the resin, from which the viscosity of the resin can be calculated and the cure state of the resin determined.