Analytical Grid Generation Method for CFD Simulations in Rolling-Piston Compressors

Abstract

The adoption of advanced three-dimensional Computational Fluid Dynamics (CFD) tools for the research and design of Rolling-Piston Compressors (RPCs) is severely constrained by the absence of efficient and reliable grid generation methods. To address this issue, this paper proposes a novel analytical grid generation method for the rotor fluid domain of RPCs based on the User-Defined Nodal Displacement (UDND). This method splits the rotor fluid domain into a vane region, a transition region and a core region according to geometric characteristics. The number of circumferential nodes in each region is adaptively determined based on the mapped lengths of the corresponding inner and outer boundaries, while node number normalization is employed to ensure precise control of the total number of nodes. Numerical tests demonstrate that the proposed method can generate O-type structured meshes with consistent topology and adaptive node allocation over the entire range of rotor rotation angles. The proposed method was verified by reference indicated pressure measurements on a small-scale RPC for refrigeration and air-conditioning applications, yielding mean absolute percentage errors of 6.30% and 7.42% and maximum pointwise relative errors of 12.70% and 20.99% at 80 and 120 Hz, respectively. The proposed method reduces the preprocessing time required for a typical CFD model of the machine from approximately 48 h to only 54 s. The improved quality and robustness of the generated mesh enhance the stability and convergence behavior of the solver, thereby enabling the use of advanced physical models, such as the real-gas equation of state, in the design and analysis of RPCs. This paper presents a rapid and reliable meshing strategy for CFD simulations of RPCs.