Flow structure and heat transfer characteristics in rotor–stator cavity with inlet at low radius

In this article, a combined experimental and computational study has been conducted to provide better understanding of the flow structure and heat transfer characteristics in a rotor–stator cavity with inlet at low radius. A new test rig was set up to investigate the heat transfer coefficient using transient thermochromic liquid crystal (TLC) technique. Six different rotational speeds, i.e., 500, 1000, 1500, 2000, 2500, 3000 rpm, were considered. The rotational Reynolds number (Reω) is ranging from 4.16 × 105 to 2.49 × 106, and the flow rate coefficient (CW) ranges from 1.3 × 104 to 4.77 × 104, with corresponding turbulent flow parameter (λT) in the range of 0.099 ≤ λT ≤ 1.527. A high-Reynolds-number realizable k–ε turbulence model was employed to simulate the flow and heat transfer characteristics in the cavity. The comparison of the local and the average Nusselt number on the surface of the main disk between the numerical results and the experimental data indicated that: (1) both the rotational Reynolds number (Reω) and a newly proposed flow pattern parameter (λTx = CwReω−1.2) dominated the flow characteristics in the rotor–stator cavity, (2) three different regimes could be determined based on the proposed turbulent flow parameter, namely, viscous regime for λTx ≤ 0.0009, co-determined regime for 0.0009 < λTx < 0.0028, and inertial regime for λTx ≥ 0.0028, and (3) the flow structure played an important role in determining the heat transfer performance inside the cavity.