Numerical Study of Heat Transfer in the Impinging Bubbly Pulsed Jet

Resumo

Numerical simulation of the influence of the frequency of pulses on heat transfer in a bubbly impinging round jet has been carried out. An axisymmetric system of non-stationary RANS equations is used in the paper, and the two-phase flow is taken into account. The turbulence of the liquid phase is described with the transport model of the components of Reynolds stress tensor, which takes into account the effect of bubbles on the modification of turbulence. The dynamics of air bubbles is simulated by the Eulerian approach. The effect of the change in the frequency of the pulses and the gas volumetric flow rate ratio on the heat transfer in a gas-liquid impinging jet is studied. The pulses causes both the suppression of heat transfer in the vicinity of the stagnation point (up to 20–25%) in the region of low frequencies at f > 20 Hz and the Strouhal number Sr > 0.34 and its intensification (up to 15–20%) at/= 100–200 Hz and Sr= 1.7–3.5 in comparison with the stationary impinging bubble jet at the same time-averaged flow rate.