A.S. Kostyukov, M.V. Nikandrov, L.A. Slavutskii

Using the modeling calculations and experimental estimation we show how the random fluctuation of inhomogeneous medium result to the inaccuracy wide using ultrasonic equipment: pulsed ultrasonic level meter and Doppler follow meter. For problem solution we use the invariant imbedding method which allows us to drive problem with edge conditions to task with initial conditions and implement effective numerical algorithms. It is shown that amplitude and phase fluctuations of ultrasonic signal have nonlinear dependence of inhomogeneous medium stochastic characteristics. The obtaining results of numerical calculations and experiments allow us estimate the limits and conditions of ultrasonic pulse and Doppler measurements inaccuracy. Statistic error of ultrasonic pulse measurements essentially depends on so a liquid surface conditions as near surface layer inhomogeneity. Maximum of nonlinear distortion and Doppler measurements inaccuracy accords to small inclusions concentration and small liquid flow speed. In general, the stochastic fluctuations of inhomogeneous medium result to increasing statistic error so as advent of variable methodical inaccuracy.