This paper presents a spray model suited for dense sprays. It captures the transient evolution of the two-phase jet characteristics resulting from hollow cone injection. The model is designed for fast model response as needed in engine system simulation. It is based on the description of the gas phase boundary layer surrounding the dense spray. Mass and momentum equations are solved for both the dispersed liquid and the continuous gas phase. Spatial gradients are resolved along one dimension, namely the main injection direction. The conservation equations are expressed in conical coordinates. The model's response is studied qualitatively and global characteristics such as the penetration behavior are compared to both experimental and CFD data. (C) 2013 Elsevier Ltd. All rights reserved.