Improved Insert For Variable Mach Number

Nozzle insert lowers wind-tunnel mach number while maintaining excellent flow quality. Essential components of improved design include sonic first throat, expansion surface, variable boundary-layer bleed, insert itself, and existing, unchanged, contour of nozzle. Modification involves creation of secondary throat and critical addition of boundary-layer bleed path between insert and original tunnel wall. Enables quick change of mach number in existing facility at relatively low cost and requires no special contouring of existing nozzle. Represents simple and cost-effective method of altering mach number in any supersonic wind tunnel.