Perfect-gas and finite-rate chemically-reacting (seven-species) nonequilbrium-air reentry flow over a sphere at Mach 20 at an altitude of 200 kft. The radius of the sphere was 0.5 inch, and wall temperature was assumed to be 3600 R. Only laminar flow conditions were considered, and wall boundary conditions were assumed to be fully catalytic .
Computational Grid: Computational grid used consisted of 65 body-normal grid points and 25 streamwise grid points for the blunt-body FNS (Full Navier-Stokes) solution. At the wall, very fine grid spacing was used, resulting in a grid spacing at the stagnation point of 9.4×10-8 inch.
PC Hardware Used: Computations were done on a very old 300 MHz Intel Pentium II PC, with 9 GB hard disk and 128 Meg RAM. However, an even older 133 MHz Pentium PC with 1GB hard disk and 32 Meg RAM would also have been sufficient for these computations.
Computational Time Required: These blunt-body FNS numerical predictions was done in a single step, starting from freestream initial conditions. The perfect-gas prediction took 343 iterations to converge, and required approximately 2 min and 54 seconds on a 300 MHz Pentium II PC. The equilibrium-air prediction took 600 iterations to converge, and required approximately 9 min and 30 seconds on the same 300 MHz Pentium II PC. The expected computing times for these computations on a 133 MHz Pentium PC should be around 30 min.
Snapshots of Predicted Flowfield:
(a) Predicted pressure contours using the seven-species (N2, O2, NO, N, O, NO+, and e-) finite-rate, chemically-reacting nonequilibrium-air gas model are compared with corresponding predictions of a perfect-gas model. Note the somewhat thinner shock layer predicted with the nonequilibrium-air gas model.
(b) Predicted temperature contours using the seven-species (N2, O2, NO, N, O, NO+, and e-) finite-rate, chemically-reacting nonequilibrium-air gas model are compared with corresponding predictions of a perfect-gas model. Note the considerably cooler shock layer predicted with the nonequilibrium-air gas model.
(c) Mass-fraction contours of N and N2 predicted using the seven-species (N2, O2, NO, N, O, NO+, and e-) finite-rate, chemically-reacting nonequilibrium-air gas model.
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