Shock System Deformation in High Mach Number Rocket Nozzles
Flow overexpansion in supersonic nozzle, with or without flow separation, leads to the formation of a shock system composed of an oblique shock rooted at the nozzle wall and a Mach reflection. A study has been conducted on the shock system deformation for nozzles with high design Mach numbers, i.e., with high wall opening angle. An experimental test campaign was conducted on three cold flow sub-scale nozzles with Schlieren imaging. An important curvature of the Mach disk was demonstrated for the nozzle with the higher design Mach numbers and low nozzle pressure ratio conditions. The experimental observations were confirmed with numerical simulations realized with DLR in-house RANS solver TAU, which showed a sensitivity of the Mach disk shape to radial pressure gradients in the flow in its vicinity. In addition, the experiments indicated instability of the Mach lens at low NPR values, corresponding to a position of the Mach disk in the region of the highest pressure gradient.
- 4.C. Génin, R. Stark, Experimental investigation of cold flow TIC nozzles, a spectral analysis, AIAA Paper 2016-4668, 2016Google Scholar
- 6.S. Langer, A. Schwöppe, N. Kroll, The DLR Flow Solver TAU – Status and Recent Algorithmic Developments, AIAA Paper 2014-0080, 2014Google Scholar
- 7.P.R. Spalart, S.R. Allmaras, A One-Equation Turbulence Model for Aerodynamic Flows, AIAA-Paper 92-0439, 1992Google Scholar