PSI - Issue 32

R. Tsvetkov et al. / Procedia Structural Integrity 32 (2021) 209–215 R. Tsvekov et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Measuring vessels with a radius of less than 2 mm are practically not used. It is also impractical to use hoses and vessels of very large diameter. The height of the liquid column h 0 in the measuring vessels in the equilibrium state is taken as 0.1 m. The storage tank is placed in such a way that it divides the distance between two adjacent sensors in a ratio of 3/5. Its volume is equal to the total volume of all hoses of HLS. This volume ratio provides the optimal conditions for potential mixing the liquid. Fig. 3 shows the results of numerical experiments that simulate the change in the liquid level in the measuring vessels and storage tank after kinematic excitation of the liquid in the system. Oscillatory processes were studied at two values of character time τ . The large characteristic time corresponds to damped periodic oscillations of the liquid level relative to its equilibrium position (Fig. 3a). At small values of this parameter, an aperiodic change in the liquid level is observed in the system (Fig. 3b).

Fig. 3. Evolution of the liquid level in the measuring vessels ( r / R =1, L = 10m) : (a) τ = 5 s and (b) τ = 0.5s .

An important technical characteristic of the hydrostatic levelling system is the stabilization time T . It represents the time when the amplitude of fluid level oscillations in all measuring vessels reaches the value given by equations (9). In the calculations, the accuracy of the estimation of the stable state is assumed to be ε = 0.1%. As shown by the numerical experiment, the stabilization time depends both on the properties of the liquid filling the HLS (density and viscosity are included in the paramete r τ) and on the geometric parameters of the system (the ratio of the radii of the measuring modules and connecting segments r/R and the length of connecting segment L ). The graphs below represent the results of numerical experiments, which show the dependence of the stabilization time T on the character time τ at a constant value of the ratio r/R or of the length of connecting segment L . In these graphs, for convenience, the stabilization time T and parameter τ are given in seconds.

Fig. 4. Stabilization time T depends on the parameter τ at different values of ratio r/R and L = 10 m.