Abstract: Blade-type multiply circular gas jets can be utilized for intensive cooling within limited area.The effects of impingement height H and jet Reynolds numbers on the heat transfer when multiply intensive circular air jets normally impinge on a smooth and flat surface are investigated experimentally. The average convective heat transfer coefficients are measured with heated thin foil technique which involves the detection of surface temperature and apples constant heat flux heating. When the jet Reynolds numbers (Re_D) vary from 5 000 to 48 500 and normalized impingement height (H/D) is 6.25. 7.50, 12.5, respectively, an increase in jet Reynolds numbers will produce higher average Nusselt numbers, and normalized impingement height with an exponent of −0.606 also have a strong impact on it. The experimental results are compared with Martin’s correlation and about 40% higher is observed. It is indicated that intensive circular nozzle array can significantly enhance heat transfer rate due to its high open porosity. The experimental data are quite well fitted by the corrected Gardon's equation. Conversely, the correlation proposed by Martin is not suitable to deduce present data and a modified geometrical function is developed.