Determination of critical flow velocity for tube-bundle with application of numerical investigation method

Anotacija

The work is devoted to the creation and application of mathematical models for the most dangerous oscillation excitation mechanisms of tubes and cylindrical form bluff structures in liquid or gas flow, as well as to the creation of efficient computational methods for description of these models. A numerical investigation method of hydrodynamic forces arising from a  separated flow and tube-bundle oscillations excited by these forces was developed by the authors. The method is based on the  application of created original tube-bundle hydroelastic oscillation excitation in a cross-flow mathematical model. Hydroelastic excitation problem is reduced to the stability analysis of undisturbed state of elastic tubes. Analysis is conducted with the assumption of linearity of the destabilizing forces. On the basis of the mathematical model, the necessary and sufficient condition for the  stability, expressed through the  dimensionless system parameters (mass, damping, velocity), was obtained. Numerical identification of the  linear hydrodynamic connection matrix algorithm for particular tube-bundles was elaborated. Verification of algorithm and programs based on it was performed by results of simulations and available experimental data correlation. A method for determination of a linear hydrodynamic connection matrix for tube-bundles with a regular arrangement of the cross-section was offered. It is based on computation of a relatively small, but sufficient for reliable results, part of the tube-bundle.