Method for determining the proportion of disperse gas phase in liquid

A method for determining a fraction of a disperse gas phase in a fluid flowing in a pipe in a flow direction by means of ultrasound, comprising:

• a) providing an ultrasonic measuring device to determine a transit time difference between two measurement signals passing through the fluid in the pipe;
• b) emitting and receiving a first measurement signal by the ultrasonic measuring device, the first measurement signal emitted with the flow direction;
• c) emitting and receiving a second measurement signal by the ultrasonic measuring device, the second measurement signal emitted against the flow direction;
• d) transmitting the measurement signals to a storage and evaluation unit;
• e) determining an individual value for the transit time difference between the first measurement signal and the second measurement signal;
• f) determining a plurality of individual values for the transit time difference by repeating steps b) to e);
• g) determining a mean value for the transit time difference from the individual values for the transit time difference;
• h) determining a scattering parameter, which is characteristic for the scattering of the individual values;
• i) providing a correlation between the mean value for the transit time difference and the change in the scattering parameter in dependence on the fraction of the disperse gas phase;
• and
• j) determination of the fraction of the disperse gas phase from the scattering parameter and the aforementioned correlation.