Study of the boundary layers in chemical laser nozzles

Chemical laser nozzles, both axisymmetric and two-dimensional, are examined to define the effect of the nozzle geometry and boundary layers on the flow. A method of defining average flow properties, which include the boundary layer influence within a one-dimensional flow formulation, is presented. The boundary layers are found to be of the same order as the nozzle exit dimensions and have a large influence on the flow. Axisymmetric and two-dimensional nozzles with the same inlet flow, geometric area ratios, and nozzle exit dimensions are found to have essentially the same average nozzle exit flow properties; the nozzle mass distributions, however, are quite different and indicate that axisymmetric nozzles may result in faster cavity mixing. Methods of including the boundary-layer influence in the laser performance and pressure recovery analyses are discussed.