Flowpath Design and Validation of the Mach 6B Nozzle for T4

A contour for a new axisymmetric Mach 6 nozzle has been designed to facilitate low Mach number testing in the T4 reflected shock tunnel facility. This nozzle, named the T4 Mach 6B nozzle, has been designed to produce a Mach 6 exit flow which has a total enthalpy corresponding to a Mach 6 flight with a total pressure of 16.6MPa and a total temperature of 1877.5 K. The nozzle-supply conditions were chosen to match those of T4 shot 12147. The nozzle has a throat-to-exit axial length of 1 m, a throat diameter of 32mm and an exit diameter of 278.77 mm, which corresponds to an exit-to-throat area ratio of 75.9. The nozzle produces a uniform core-flow diamond with a maximum axial length of 1.1 m and a maximum diameter of 230 mm. Cross-sectional flow profiles taken in the core flow area at the exit plane of the nozzle show that the exit flow is uniform - Mach number varies by 0.6%, flow angularity varies by 0.15%, and Pitot and static pressures vary by 2.7 and 4%, respectively. The nozzle design was validated through comparison of Pitot pressure distributions at select cross planes downstream of nozzle exit between experiments and simulations. Excellent agreement between the experimental and numerical Pitot pressure distributions is achieved at all measurement planes. The experimentally-measured Pitot pressure distributions confirm that the nozzle outflow is reasonably axisymmetric and that there is good level of uniformity in the core-flow region produced by the nozzle. Further simulations and experiments both show that the nozzle design is robust enough to reproduce uniform flow at off-design conditions and that the distribution of Pitot-to-nozzle-supply pressure ratio is unaffected by nozzle-supply conditions.