Gullfiber Ab

Per Holmgren

Arne Thomsen

Anders P Ransheim

A method and an apparatus for measuring the flow velocity of a flow, stream or jet of molten radiation emitting material, in particular a freely falling jet of molten glass. The intensity of the radiation emitted from a limited section of the material flow is detected by means of two radiation detectors at two separate locations mutually spaced apart by a predetermined distance along the flow path of the material flow. From the output signals of the two radiation detectors all pulse-like amplitude variations having an amplitude exceeding a predetermined magnitude are discriminated. These pulse-like amplitude variations originate from randomly occurring, local, descrete, short variations in the intensity of the radiation emitted by the material flow caused by randomly occurring inhomogeneities in the material, for instance in the form of air bubbles in a jet of molten glass. The time interval between a pulse-like amplitude variation in the output signal from the upstream detector caused by an inhomogeneity in the material flow and the occurrence of a pulse-like amplitude variation in the output signal from the down-stream detector, which has been caused by the same inhomogeneity in the material flow, is measured and used as a measure of the travel time of the material flow between the detector locations for calculating the flow velocity of the material flow. Also the volumetric flow rate of the material flow can be determined by measuring also the diameter of the material flow with the aid of a linear array of photo diodes and calculating the volumetric flow rate on the basis of measured values of the flow velocity and the diameter.

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Angelholm, Sweden

Per Holmgren