An experimental investigation of flow structure and heat transfer in an impinging annular jet

The paper presents the results of an experimental study of flow and heat transfer in an impinging annular jet. Using the PIV-system the distribution of average and pulsation velocities was measured; and heat fluxes and their pulsations were detected using miniature heat flux sensors. The measurement results have been compared at identical mass flow rate of air with similar data for a round jet with a diameter equal to the outer diameter of the annular jet. It is shown that under these conditions of comparison the values of velocity and turbulent pulsations in the annular jet are significantly higher than the same values in the round jet. The heat transfer intensity of the impinging annular jet is also higher than that of the round jet, and the degree of heat transfer enhancement depends on the annular gap size and distance from the nozzle to the obstacle.