Two -stage ejector based pressure recovery system for small scale SCOIL

Abstract The chemical oxygen–iodine laser (COIL) is the only chemical laser based on electronic transitions. It is essentially a low pressure, high flow rate system requiring high capacity vacuum pumps for its operation in its standard form. Since, the output power of COIL systems is a direct function of the input fuel rate, power scale up of these systems is a definite possibility which can be utilized in numerous civil and defense applications. However, scaling up and field applications necessitates exploration of possible means of reduction in size of vacuum systems for which an efficient ejector based pressure recovery system qualifies to be the prime candidate. In this paper, the gas dynamic aspects of a two-stage peripheral air ejector system suitable for a 500 W class COIL employing a flow rate of ∼3 gm/s have been presented. The experimental results with this developed ejector system for the simulated flow conditions of the laser under vacuum have indicated a start up pressure in excess of ∼50 Torr in the first stage and more than ∼600 Torr in the second stage. The experimentally observed flow parameters at various locations in the flow field have been validated with the computational results obtained employing Fluent 6.1 software using 2-D axi-symmetric formulation.