Based on combined Infrared Thermography and numerical simulations, the heat transfer and flow performance in a vortex cooling configuration with 5 nozzles were investigated at various Reynolds numbers and temperature ratios. Validation was conducted between experiment and numerical simulation and results showed that the k-omega turbulence model has the best accuracy to predict the vortex cooling behavior. High Nusselt number regions appear under each nozzle in all cases, but air from downstream nozzles is easily impacted because of the "anti-cross flow" ability. Along the axial direction, targeting surface has a fluctuant heat transfer coefficient distribution, while along the circumferential direction, the heat transfer coefficient decreases linearly. Overall heat transfer coefficient increases with increasing Reynolds number and decreasing temperature ratio. Especially, the influence of temperature ratio under 3 setting methods is compared and discussed in detail, revealing the fundamental impact of temperature ratios. A globally-averaged Nusselt number correlation is presented over 22,000 < Re-D < 39,000, 0.88 < TR < 0.94, and results in this paper are compared with other vortex cooling systems. (C) 2018 Elsevier Ltd. All rights reserved.