Pressure recovery studies on a supersonic COIL with central ejector configuration

A chemical oxygen-iodine laser (COIL) is an electronic transition, low pressure, high throughput system. The field use of this laser demands the development of suitable pressure recovery systems. Ejector based pressure recovery systems form a potent alternative for open cycle COIL operation. The two possible configurations of motive gas injection in ejectors are peripheral and central. The present paper focuses on the investigation of a central injection low pressure ejector operated with a small scale supersonic COIL (SCOIL). The ejector handles a motive flow of nearly 120 g s⁻¹ and an entrained laser flow of nearly 3 g s⁻¹. The predicted geometry using integral methods has been validated numerically by employing Fluent 6.1 software in a 2-d axisymmetric viscous turbulent flow formulation. The numerical predictions have been experimentally validated, which indicate a pressure recovery of 63 Torr at design conditions. The results also show that the recovered pressure improves to 75 Torr for an off-design condition of higher motive flow rate.