An evaluation of methods for the time-domain simulation of turbulence excitations for tube bundles subjected to non-uniform flows
Résumé
The present paper addresses the problem of achieving adequate modelling of the turbulence excitations,
when performing nonlinear time-domain computations for the predictive dynamical analysis of gapsupported tube bundles of nuclear power-plant components – namely steam generators. Although in most
publications the details on time-domain implementations of turbulence excitations are seldom supplied, it is a
nontrivial task to provide adequate time-domain force functions which rightly account for the spectral
properties, the space correlation, as well as the local magnitude of the flow velocity field. Oversimplified
approaches may lead to inadequate modelling of the excitation, and hence to unreliable predictive results.
We recently proposed a simple and consistent method to simulate the continuous space-correlated flow
force field (Antunes et al, 2008), using a finite set of uncorrelated discrete random forces, which are
computed based on the theoretical formulation for the linear modal responses of the excited tube. Here we
investigate whether such computationally efficient approach is effective, even when dealing with the
nonlinear vibro-impact responses of gap-supported tubes subjected to non-uniform flows. Illustrative linear
and nonlinear tube response computations using our simple excitation method are compared with those
obtained by modelling the turbulence through a partially correlated random field, computed using the more
computationally intensive techniques developed by Shinozuka et al (1971, 1990).