International audienceThe average-passage equation system (APES) provides a rigorous mathematical framework to account for the UBRI in steady state environment by introducing the deterministic correlations (DC). How to model the DC is the key in APES method. The primary purpose of this study is to develop a DC model for compressor routine design. A 3D viscous unsteady and time-averaging CFD flow solver is developed to investigate the APES technique. Steady, unsteady and time-averaging simulations are conducted on the investigation of the UBRI in the first stage of NASA 67 compressor. Based on DC characteristics and its effects on time-averaged flow, an exponential decay DC model is proposed and implemented into the time-averaging solver. Based on the unsteady simulation, the proposed model is validated by comparing DC distributions and mean flow fields. The comparison indicates that the proposed model can take into account the major part of UBRI and provide significant improvements for predicting spanwise distributions of flow properties in axial compressors, compared with the steady mixing plane method