Abstract: A manipulation path for monitoring the flow profile at the inlet of a flow sensor, the manipulation path designed to conduct a fluid measuring medium, includes a first end region and a second end region, between which a manipulation section is located that is designed such that secondary flows are formed in the measuring medium as a result of the measuring medium flowing through the manipulation section. Two different variants of a system, each including a flow sensor and the manipulation path according to the present disclosure, are disclosed.

Abstract: A method for detecting bubbles or droplets of a first medium in a fluid second medium flowing through a measuring pipe includes: heating a first heating element and a second heating element, which are each arranged on the measuring pipe and at a distance from each other; simultaneously sensing a first ambient temperature at the first heating element by a first sensor and a second ambient temperature at the second heating element by a second sensor; determining a first variable of the first sensor corresponding to the first ambient temperature and a second variable of the second sensor corresponding to the second ambient temperature; forming a difference between the first variable and the second variable; and comparing an absolute value of the difference with a reference threshold value, wherein the presence of a bubble or droplet is detected when the absolute value at least briefly exceeds the reference threshold value.

Abstract: A method for operating a thermal sensor, wherein the thermal sensor includes a sensor element and an electronics, the sensor element in thermal contact with a container, in which a measured medium flows with a flow velocity, the sensor element periodically heated by an alternating voltage and, at the same time, a temperature of the sensor element is registered versus time, wherein the electronics determines a measured variable of the measured medium based on a comparison of the third harmonic oscillation of the alternating voltage with the third harmonic oscillation of the temperature, including calculating a phase shift between the third harmonic oscillation of the alternating voltage and the amplitude of the third harmonic oscillation of the temperature, and wherein a frequency of the alternating voltage is selected to achieve a penetration depth of an emitted heat of the sensor element into the measured medium at essentially zero flow velocity.

Abstract: A thermal flow meter for measuring a flow rate of a gas includes: a measurement channel for guiding the gas between a channel inlet and a channel outlet; a thermal flow sensor disposed in the measurement channel; a density sensor including an oscillator operable to be acted upon by the gas; a temperature sensor element configured to determine a gas temperature; a pressure sensor element configured to determine a gas pressure; and a measuring-operating circuit configured to: determine a density value of the gas based on a natural frequency of the oscillator; identify a composition of the gas based on the density value, the gas pressure, and the gas temperature; and as a function of the composition, output a flow rate measured value corrected with respect to a cross-sensitivity of the flow rate to the composition of the gas based on flow rate-dependent signals of the thermal flow sensor.

Abstract: A method for operating a thermal flow sensor includes: bringing a measuring medium into thermal contact with a sensor element of the flow sensor and periodically heating the medium using an AC voltage introduced into the sensor element; simultaneously detecting a maximum amplitude of a temperature and/or a phase shift between a curve of the AC voltage and the curve of the temperature; adjusting the detected maximum amplitude and/or the detected phase shift using calibration data; determining an isoline using the adjusted maximum amplitude and/or the adjusted phase shift based on model of the flow sensor, wherein the isoline has a plurality of value pairs of thermal conductivity and thermal capacitance of the medium; deriving a medium information from the isoline; and performing a flow measurement by converting signal values from the sensor element into measurement values of an effective flow velocity of the medium using the medium information.

Abstract: A method for operating a thermal flow sensor includes: bringing a measuring medium into thermal contact with a sensor element of the flow sensor and periodically heating the medium using an AC voltage introduced into the sensor element; simultaneously detecting a maximum amplitude of a temperature and/or a phase shift between a curve of the AC voltage and the curve of the temperature; adjusting the detected maximum amplitude and/or the detected phase shift using calibration data; determining an isoline using the adjusted maximum amplitude and/or the adjusted phase shift based on model of the flow sensor, wherein the isoline has a plurality of value pairs of thermal conductivity and thermal capacitance of the medium; deriving a medium information from the isoline; and performing a flow measurement by converting signal values from the sensor element into measurement values of an effective flow velocity of the medium using the medium information.