Langley Research Center Turbulence Modeling Resource

Return to: Turbulence Modeling Resource Home Page

AJM163OD: Off-Design Mach 1.63 Axisymmetric Jet

See the related Temperature-Matched Mach 1.63 Axisymmetric Jet and Heated Mach 1.63 Axisymmetric Jet cases.

The purpose here is to provide a validation case for turbulence models. Unlike verification, which seeks to establish that a model has been implemented correctly, validation compares CFD results against data in an effort to establish a model's ability to reproduce physics. A small sequence of nested grids of the same family are provided here if desired. Data are also provided for comparison. For this particular supersonic jet case, the data are from experiment.

The experiment involved a supersonic jet issuing from an axisymmetric convergent-divergent nozzle with an exit diameter, Djet = 2 in. (50.8 mm). The jet exit Mach number for the particular case here is approximately Mjet=ujet/ajet=1.63. The divergent nozzle contour was designed with the Method of Characteristics to be yield a nearly shock-free flow in the divergent section of the nozzle and the jet plume. The nozzle pressure ratio (NPR) was purposefully set lower than that required to isentropically expand the flow to the nozzle exit, given this Mach 1.63 nozzle's exit to throat area ratio. This produces an overexpanded jet with significant oscillations in the jet potential core that are reflected in all flow quantities, such as centerline velocities (see plot below). The NPR used (3.01) would provide a perfectly expanded flow for a nozzle designed to achieve Mach 1.36 at the nozzle exit. The nozzle's supply plenum was heated such that the jet exit static temperature (if it had been expanded to Mach 1.36) would be 233 K higher than the ambient static temperature.

In the experiment, the axisymmetric jet exits into quiescent (non-moving) air. However, because flow into quiescent air is difficult to achieve for some CFD codes, here the CFD is computed with a very low background ambient conditions (Mref=0.01, moving left-to-right, in the same direction as the jet). This boundary condition difference has some effect, but testing has indicated that the influence is relatively small and Mref=0.01 represents a reasonable compromise. The appropriate jet conditions are achieved by setting total pressure and temperature at the inflow plane to the nozzle, as shown in the figure.

It is important to note that this axisymmetric case is not a planar two-dimensional computation; it uses a periodic (rotated) grid system with appropriate boundary conditions on the periodic sides of the grid.

GRIDS

The experimental operating conditions are summarized in the following table:

^*For this case, the NPR and T_t would yield a perfectly expanded jet velocity of 622.9 m/s. However, computations indicate a normal shock (from the centerline outward a small radial distance) early in the jet exhaust which reduces the jet total pressure, and results in a modified "fully expanded velocity" of 594.0 m/s for expected computations and subsequent nondimensionalizations shown here. This behavior was also observed in the experimental measurements.

This case (referred to as "Case 4") was one of five examined in the 6th AIAA Propulsion Aerodynamics Workshop (PAW6). The related Temperature-Matched Mach 1.63 Axisymmetric Jet and Heated Mach 1.63 Axisymmetric Jet cases are two of the other cases considered in PAW6.

The experiment yielded measured velocities as well as turbulence quantities downstream of the jet exit using PIV. Velocity and turbulence profiles of interest are provided at the centerline (r/Djet = 0), along the nozzle lipline (r/Djet = 0.5), and at several x-locations in the jet. There is mean static temperature (T) and RMS of temperature (T') data, collected with rotationally resolved Raman scattering spectroscopy, along the nozzle centerline and lipline as well as at several x-locations.

Several RANS and scale resolving analyses were considered and are documented in:

• Georgiadis, N. J., Wernet, M. P., Winkler, C. M., Benton, S. I., and Connolly, B. J., "Summary of the 6th Propulsion Aerodynamics Workshop Nozzle Test Case: Heated Supersonic Axisymmetric Jets," AIAA Paper 2024-0749, Jan 2024, https://arc.aiaa.org/doi/abs/10.2514/6.2024-0749

A tar file of the data for all 5 PAW6 cases is in the link below. As mentioned above, this off-design Mach 1.63 jet is listed as "Case 4."

• PAW6_nozzle_TMR.tar.gz

The experimental data references are:

• Georgiadis, N. J., Wernet, M. P., Locke, R. J., and Eck, D. G., "Mach Number and Heating Effects on Turbulent Supersonic Jets," AIAA Journal, Vol. 62, No. 1, Jan. 2024, pp. 31-51, https://arc.aiaa.org/doi/full/10.2514/1.J063186
• Wernet, M. P., Georgiadis, N. J., and Locke, R. J., "Raman Temperature and Density Measurements in Supersonic Jets," Experiments In Fluids, Vol. 62, No. 3, 2021, pp. 1-21, https://link.springer.com/article/10.1007/s00348-021-03162-2
• Wernet, M. P., Georgiadis, N. J., and Locke, R. J., "Velocity, Temperature, and Density Measurements in Supersonic Jets," NASA/TM-20205007269, October 2020, https://ntrs.nasa.gov/citations/20205007269 (the entire raw data set is also available here)

What to Expect:

RESULTS	LINK TO EQUATIONS	MRR Level
SST-Vm	SST-Vm eqns	3

(Other turbulence model results may be added in the future.)
 
 

Return to: Turbulence Modeling Resource Home Page

Recent significant updates:
None

Privacy Act Statement

Accessibility Statement

Responsible NASA Official: Ethan Vogel
Page Curator: Clark Pederson
Last Updated: 09/06/2024