The invention relates to a measuring method and a measuring device for
liquid drop particles in a wet-steam region. An
ultrasonic excitation signal acquires ultrasonic signals with three different frequencies by adopting a mode of superposing
waves; the
processing and analyzing process of the ultrasonic signals in a computer comprises the following steps: performing
fast Fourier transform on the obtained signals to obtain ultrasonic
signal amplitudes with three frequencies, and calculating to obtain sound attenuation coefficients; obtaining particle
diameter values of the
liquid drop particles according to the relationship between the measured particle
diameter values of the
liquid drop particles and the ratio of the sound attenuation coefficients with three frequencies; likewise, obtaining a
volume concentration value according to the relationship between the
volume concentration value and the sound attenuation coefficients, and obtaining a
humidity value of
wet steam according to the conversion relationship between the
volume concentration and the
humidity. The measuring device is simple in structure and low in cost; compared with the measuring method for the
wet steam by adopting other principles, the measuring method disclosed by the invention has the advantages that ultrasonic
waves have strong penetrating power; an ultrasonic
transducer can normally work in a severe environment; online measurement of particles sizes, volume concentration and
humidity of the liquid drop particles in the
wet steam region with higher concentration at the final stage of a low-pressure cylinder can be realized without precision correction.