EFFECT OF THE SHAPE OF PULSES ON HEAT TRANSFER AT THE STAGNATION POINT OF A NONSTATIONARY AXISYMMETRIC IMPACT GAS-DROPLET JET

A numerical investigation was carried out to study the influence of the shape of pulses (rectangular, triangular, and sinusoidal) on heat transfer at the stagnation point of an impact pulsed gas-droplet jet. It is shown that in a nonstationary two-phase impact jet both an increase and suppression of heat transfer are possible in comparison with stationary flow for all pulse shapes studied. In the region of small distances between the pipe cut and the barrier (up to four pipe diameters) in the pulsed gas-droplet jet, the heat transfer at the stagnation point increases, while at large distances (more than five pipe diameters), the heat transfer rate decreases in the pulsed flow. This is typical of all the pulse shapes studied in this work An increase in the Reynolds number causes a decrease in heat transfer intensification, and the results of calculations for all types of signal shapes approach the stationary mode of a two-phase impact jet.