Abstract: Based on the existing Taitel map and Ulbrich & Mewes map,a new flow pattern map was proposed based on the analysis of the experimental data.According to this map,three typical flow patterns can occur in vertically upward shell-side flow in tube arrays,namely,the bubbly,churn-bubbly and intermittent flows.In different patterns,the typical time-history,power spectral density（PSD） curves and Strouhal numbers associated with the peak PSD of excitation forces working on tube bundle are given.There are obvious effects of flow pattern on the time-history of excitation forces,the shapes and frequency distribution of PSD curves.