The motivation for the development of a compact device for determining flow velocities in fluids is the occurrence of complex flow patterns in quenching baths. Red-hot structural components are placed in oil immersion baths of this type to quench them. Because of the high temperatures of these components, the temperature of the immersion bath increases when they are immersed in the bath. To obtain uniform results with respect to the hardening of the parts, it is necessary to keep the bath temperature at a uniform level by cooling the quenching fluid continuously. So that it can be cooled, the fluid is discharged either continuously or discontinuously from the bath, conducted through a heat exchanger, and then returned to the bath. As a result of this circulation of the quenching fluid, flows develop in the bath. The workpieces introduced into the bath and the circulation of the fluid cause local differences in the flow states of the hardening oil. The temperature of the fluid in the bath does not equalize in an optimum manner either. As a result, the heat transfer between the workpieces and the quenching fluid is not constant at all points. The circulation of the oil for cooling therefore leads to differences in the hardening of the parts in the bath. The goal was therefore to use a flow probe to make it possible to see these types of differences in the convection stares of quenching baths and then to minimize these local differences by the use of suitable devices in the bath.
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