When γ ray penetrates a substance

its intensity will be weakened with the increase of the thickness of the substance. When the cavitation flow is measured the absorber is the mixture of water and vapor and the relation between the impulse counting rate N of the counter and vapor thickness can be expressed as follows:

N=N

0

'e

μwdg

N measured by the meter could show the status of cavitation flow. The present test was conducted on a Venturi Meter and a model hydraulic turbine. The test results were compared with the results of the supersonic method and the energy method. The instrument has shown to be practically stable and easy to operate. The application of cavitation measurement is feasible.