This article presents an experimental investigation of the heat transfer characteristics in a typical rotor-stator system with cooling air inlet at low radius under different dimensionless flow rate (C-w) ranges from 1.32 x 10(4) to 4.87 x 10(4) at five different rotational speeds, i.e., 500, 1000, 1500, 2000 and 2500 rpm with a large range of rotational Reynolds numbers 4.18 x 10(5) <= Re-omega, <= 2.484 x 10(6). A transient thermochromic liquid crystal (TLC) technique is employed to obtain the detailed distribution of the Nusselt number (Nu) on the surface of the rotor with effective rotating radius of 350 mm as well as with a maximum gap of 67 mm between the rotor and stator. The relationship between the Nusselt number (Nu) and the turbulent flow parameter (lambda(T)) which has been identified as the parameter governing heat transfer in the rotating disk system is experimentally explored. A numerical model is developed for the investigation of the flow structure inside the rotating cavity and provides a basis for further study in explaining the heat transfer behavior over the rotating disk. It is found that the heat transfer characteristics are strongly affected by the flow structure. Numerical results also clearly show the existence of three flow regimes inside the cavity, namely, viscous regime, co-dominated regime, and inertial regime. The heat transfer characteristics in a rotor-stator system are well explained by the flow structure obtained in the paper. (C) 2014 Elsevier Ltd. All rights reserved.