This research investigates the operational performance of ejection systems integrated into drilling rock-breaking assemblies. The object of the study is a near-bit reaming-ejection device (RED), which is installed in the bottom hole assembly (BHA) and is intended to improve bottom hole cleaning efficiency during drilling through the operation of integrated ejection systems that ensure effective entrainment of drilling fluid jets from the near-bit region enriched with drilled cuttings and fragmented rock. The subject of the study is the flow of drilling fluid through ejection nozzles with different cross-sectional geometries, which determine the hydrodynamic characteristics of the fluid flow. The design of the near-bit RED combines two systems – a drilling reamer and ejection devices – which makes it possible to reduce the space occupied within the BHA, improve borehole diameter stabilization, and enhance bottom hole cleaning efficiency simultaneously. Computational fluid dynamics simulations of ejection nozzles with various cross-sectional geometries (circle, triangle, square, pentagon, regular hexagon, and specially oriented hexagon) showed that the increase in the velocity of the fluid-flow core issuing from the nozzle model with a specially oriented hexagonal cross-section amounted to approximately 4.5 % compared with the baseline design (circular cross-section) and approximately 5.5 % compared with the remaining models. It was found that the nozzle design with a specially oriented hexagonal cross-section enables the fluid flow to be directed at an angle toward the borehole wall. The results of additional computational fluid dynamic simulations made it possible to establish a relationship between the angle of deviation of the drilling fluid flow from the vertical and the value of the control angle of the specially oriented hexagonal cross-section of the ejection nozzle. This relationship provides an opportunity for purposeful control of the drilling fluid trajectory through modification of the nozzle geometry. This capability may be used for additional sealing of borehole walls without significant deviation from the designed borehole diameter.