Internal Performance of Highly Integrated Deployable Exhaust Nozzles

An investigation was conducted in the Jet-Exit Test Facility of the Langley 16-Foot Transonic Tunnel to evaluate the internal performance of highly integrated deployable exhaust nozzles (HIDEN) applicable to advanced short-takeoff and vertical-landing tactical aircraft. This investigation studied the performance of four HIDEN nozzle concepts in both the forward (thrust) and vertical (lift) operation modes. Two plenum designs with different offtake duct geometries varied the vertical distance between the plenum centerline and bearing plane surface centerline. Four plenum centerbodies with interchangeable blockers were tested to simulate engine fan- and core-mounted nozzle installations. All tests were conducted with no external flow and nozzle pressure ratio (NPR) was varied from 1.5 to approximately 6.0. Results indicate that the HIDEN nozzle concept has internal performance characteristics comparable to thrust-vectoring convergent-divergent nozzles. However, the exhaust flow was slightly under-turned with each nozzle design, which resulted in a cosine thrust loss. Nozzles installed on the offset plenum had higher internal performance than the same nozzles installed on the centerline plenum throughout the entire NPR range investigated. Changing operation mode had only small effects on internal performance characteristics. Centerbody and blocker effects were also small.