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Sajben Transonic Diffuser

Figure 1 is described in the surrounding text

Figure 1. Geometry and flow field for Sajben transonic diffuser.

Flow Description

This validation case examines the transonic air flow through a converging-diverging diffuser with comparisons to experimental data obtained by Sajben et al. Table 1 lists the conditions at the inflow.

Table 1. Flow conditions.
Total Pressure (psia) 19.58
Total Temperature (R) 500.0
Angle-of-Attack (deg) 0.0
Angle-of-Sideslip (deg) 0.0
Weak Shock Outflow Static Pressure 16.05
Strong Shock Outflow Static Pressure 14.10

The strength of the internal shock is controlled by the static pressure at the outflow. The static pressures imposed at the outflow for the weak-shock and strong-shock cases are listed in Table 1.


The two-dimensional geometry of the Sajben diffuser is shown in Fig. 2. The throat is located at x = 0 inches and has a height hthr of 0.14435 feet (44 milli-meters or 1.7322 inches).

Figure 2 is described in the surrounding text

Figure 2. Geometry of the Sajben transonic diffuser.

The geometry can be obtained from the grid file sajben.x.fmt, which is in the Plot3d format (3D, multi-block, formatted, whole). The lower surface is the J1 grid line and the upper surface is the JMAX grid line. These coordinates are also available in the files lower.pts and upper.pts. The units are inches.

Comparison Data

The experimental data are from the references listed below. The files can be found in the studies below.

Computational Studies

Table 2. Computational studies peformed for the Sajben transonic diffuser case.
Study Category Person Comments
Study #1 Benchmark Validation C. Towne Compares NPARC, WIND, NXAIR
Study #2 Benchmark Validation D. Yoder Compares NPARC and WIND with turbulence models.
Study #3 Benchmark Validation J. Slater Compares versions and turbulence models of WIND.
Study #4 Benchmark Validation S. Mohler Validation of Wind-US unstructured flow solver.
Study #5 Benchmark Validation J. Dudek Validation of Wind-US unstructured 3.146.


Bogar, T. J., Sajben, M., and Kroutil, J. C. (1983) "Characteristic Frequencies of Transonic Diffuser Flow Oscillations," AIAA Journal, Vol. 21, No. 9, pp. 1232-1240.

Bogar, T. J. (1986) "Structure of Self-Excited Oscillations in Transonic Diffuser Flows," AIAA Journal, Vol. 24, No. 1, pp. 54-61.

Chen, C. P., Sajben, M., and Kroutil, J. C. (1979) "Shock Wave Oscillations in a Transonic Diffuser Flow," AIAA Journal, Vol. 17, No. 10, pp. 1076-1083.

Hsieh, T., Bogar, T. J., and Coakley, T. J. (1987) "Numerical Simulation and Comparison with Experiment for Self-Excited Oscillations in a Diffuser Flow," AIAA Journal, Vol. 25, No. 7, pp. 936-943.

Hsieh, T., Wardlaw A. B. Jr., Bogar, T. J., and Coakley, T. J. (1987) "Numerical Investigation of Unsteady Inlet Flowfields," AIAA Journal, Vol. 25, No. 1, pp. 75-81.

Sajben, M., Bogar, T. J., and Kroutil, J. C. (1984) "Forced Oscillation Experiments in Supercritical Diffuser Flows," AIAA Journal, Vol. 22, No. 4, pp. 465-474.

Salmon, J. T., Bogar, T. J., and Sajben, M. (1983) "Laser Doppler Velocimeter Measurements in Unsteady, Separated Transonic Diffuser Flows," Vol. 21, No. 12, pp. 1690-1697.

Last Updated: Wednesday, 10-Feb-2021 09:38:59 EST