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To model sprays from pintle type nozzles with large hollow cone angle and high injection pressure, the correct flow field in the near region must be predicted. A new model was implemented in KIVA-3V code, which adopts the theory of steady gas jet to correct the relative velocities between the drop and gas phases, based on the existence of quasi-steady part of the conical spray and an assumption of equivalent gas jet. Accordingly, the structure of the sprays is defined into three parts: 1. initial part that the gas phase velocity is set to the assumed gas injection velocity; 2. quasi-steady part where the component of velocity in the symmetric line direction of the spray is corrected; 3. stagnation part which is left unchanged. This new model is referred to as the Relative Velocity Correction (RVC) model, and is a set of empirical equations that calculate the sectional distribution of the gas-phase velocity along the symmetric line of the sprays.

A relative velocity correction model (RVC), combined with the drop tracing system and spherical coordinate transformation, was developed and implemented in KIVA-3V code to yield grid-independent results for the spray simulations, especially for 3-D cases. The model applies the theory of steady turbulent jet flow to obtain sectional distribution of the gas-phase velocity along the spray axial in near region, which is used to correct the relative velocity between the drop and gas phases. The computed results were compared with the experimental data for both single-hole and three-hole fuel injections, including the spray tip penetrations and the spray images. The comparison shows that the RVC model performed well for all the cases.