Targeted Meshing Guidelines for Accurate Axisymmetric CFD Prediction of Supersonic Ejector Performance for Sustainable Refrigeration Systems

Supersonic ejectors are axisymmetric devices governed by radially symmetric flow phenomena and employed in cooling and refrigeration systems. This paper investigates the sensitivity of their numerical simulation to the meshing strategy by evaluating eight distinct mesh configurations against three criteria: entrainment ratio, internal flow characteristics, and computational time. The meshes are grouped into three categories according to the location of the remeshing relative to the point at which the secondary flow enters, and compared against a reference case. The global performance analysis reveals that coarse meshes underestimate the ejector’s operating range by nearly 10% and fail to resolve a distinct critical point, whereas insufficient refinement of the upper part of the first flow contact region overpredicts the entrainment ratio by nearly 1% under critical conditions. As a consequence, the effective area of the secondary throat proves sensitive to mesh density, producing deviations of around 0.5% in the secondary mass flow. The study also quantifies the computational trade-off, demonstrating that calculation time in subcritical working conditions scales super-linearly with cell count. Notably, meshes that precisely resolve the initial flow interaction zone achieve better numerical stability and require fewer iterations per cell than topologically inefficient meshes with fewer cells.