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Heterogeneous catalysis effects in Mars entry problem

Heterogeneous catalysis effects in Mars entry problem. Valery L . Kovalev Moscow State University , Russia ERICE-SICILY:1-7 AUGUST 2005. Schematic of flow field with catalytic recombination, excited state production and quenching.

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Heterogeneous catalysis effects in Mars entry problem

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  1. Heterogeneous catalysis effects in Mars entry problem Valery L. Kovalev Moscow State University, Russia ERICE-SICILY:1-7 AUGUST 2005

  2. Schematic of flow field with catalytic recombination, excited state production and quenching.

  3. Calculated flux to MESUR spacecraft with various catalytic boundary conditions.

  4. THREE TYPES OF SILICONIZED COATING MATERIALS • Coating I : the glassy coating of the <<Buran>> orbiter tile heat shield based on the SiO2 - B2O3 - SiB4 system • Coating II: an oxidant — resistant carbonaceous coating based on alumina borosilicate glass with a MoSi2 admixture • Coating III: a coating made up of a new composite material based on the Hf — Si — С — В system.

  5. Nonequilibrium jet from plasmatron flowing around butt-end probe (Mach number)

  6. Experimental regimes Parameters Regimes 1 2 3 4 5 6 Te, К 3320 4360 5800 6256 6600 6875 Vs, m/s 47,3 76,1 105,6 118,0 145,0 164,0 qfcW, Wt/cm2 4 6,4 74,4 103,7 130,0 175,0 208,0 N, kWt 29 37 44 52 64 72 p, Pa 10,5 17,5 24,5 26,2 33,75 38,8

  7. CATALYTIC MECHANISM chemical adsorption and desorption atoms 1. O + SV OS Eley — Riddel reactions 2. OS + O  SV + O2 3. OS +CO  SV+ CO2 physical adsorption and desorption 4. О + FV Of, diffusion to the nearest chemisorptions site 5. Of + SVОS + FV Lengmuir — Hinshelwood recombination 6. Of + OS O2 + FV + SV, 7. OS + OS O2 + 2 SV

  8. MASS RATES OF SPECIES FORMATION IN HETEROGENEOUS CATALYTIC REACTIONS

  9. Elementary rate coefficients

  10. Curve a1ER a3ER a4ER 5 7 EOad ECOad E1ER E3ER E4ER a 0.015 0.015 0 0.025 0 300 0 25 15 0 b 0.038 0,038 0 0.025 0 280 0 25 15 0 с 0.018 0.018 0 1.0 0 280 0 15 10 0 d 0.038 0,038 0.038 0.025 0.013 280 280 25 15 25 Coating II 0.013 0.016 0 0.016 0 380 0 20 25 0 Coating III 0.042 0.042 0 0.025 0 400 0 10 25 0 DETERMINATION OF THE MODELPARAMETERS • SIMPLIFYING ASSUMPTION • ads = const (1); Q (A-S) = QS (2) • VALUES OF THE MODEL PARAMETERS (Reaction 1-3) The r.m.s. deviation of the calculated heat fluxes from the measured ones did net exceed 5 %.

  11. Temperature dependence of the heat fluxes to coating I at stagnation point

  12. Temperature dependence of the effective coefficients of heterogeneous recombination for coating I

  13. Temperature dependence of the effective coefficients of heterogeneous recombination for coating III

  14. Experimental regimes Parameters Regimes 1 2 3 4 5 6 Te, К 3320 4360 5800 6256 6600 6875 Vs, m/s 47,3 76,1 105,6 118,0 145,0 164,0 qfcW, Wt/cm2 4 6,4 74,4 103,7 130,0 175,0 208,0 N, kWt 29 37 44 52 64 72 p, Pa 10,5 17,5 24,5 26,2 33,75 38,8

  15. Table. 1 Reactions with physical adsorptionatoms and model parameters N Reaction A E Q Ref. 1 O + SV OS 0,025 0 300 [1] 2 .OS + O  SV + O2 0,015 25 _ _ ,, _ 3 OS +CO  SV+ CO2 0,015 15 _ _ ,, _ 4 О + FV Of 0,5 0 20 [2,3] 5 Of + SVОS + FV 0,053 0 _ _ ,, _ 6 Of + OS O2 + FV + SV 0,053 0 _ _ ,, _ 7 OS + OS O2 + 2 SV 0,02 125 _ [4] 1,0 500 _ [5]

  16. Heat fluxes on the surface taking into account processes with physical adsorbed atoms

  17. Temperature dependences of effective recombination probability of oxygen atoms

  18. Heat fluxes on the surface taking into account the recombination of carbon atoms

  19. H, km V, m/s P, kg/m3 T, К 75.92 5800 3.0110-6 129 67.89 5791 9.5110-6 130 59.87 5769 2.8910-5 134 51.84 5690 8.3710-5 140 43.82 5536 2.2710-4 148 36.79 5172 5.8110-4 158 28.95 4539 1.2310-3 167 23.16 3471 2.2710-3 174 17.89 2549 3.8410-3 182 Mini-probe forebode configuration and computational domain Mole fraction CO2 distribution Temperature distribution. H = 51.84 km, (sizes on Figure are indicated in cm) Free stream entry conditions

  20. Flight altitude dependence of the heat fluxes to different coatings at the stagnation point for the Mars miniprobe

  21. MARS miniprobe surface equilibrium temperature along the trajectory for different coatings

  22. Configuration of space vehicle MSRO

  23. The distribution of heat fluxes across the frontal surface of MSRO 50 q 2 В т / с м , w 40 30 4 3 20 2 10 1 0 S , м 0 0.4 0.8 1.2 1.6 2 Р и с . 2 . В л и я н и е г е т е р о г е н н ы х к а т а л и т и ч е с к и х п р о ц е с с о в н а т е п л о в ы е п о т о к и к т е п л о з а щ и т н о м у э к р а н у

  24. The distribution of heat fluxes across the bottom surface of MSRO

  25. Surface equilibrium temperature across the bottom surface of MSRO

  26. Effect of physical adsorption for the bottom surface of MSRO

  27. Summary • On the basis of the Langmuir layer theory, a model of the interaction of dissociated carbon dioxide mixture with a catalytic surface is developed. This model takes into account both chemical and physical adsorbed atoms. • Comparison of the calculated heat fluxes with measured ones show that the model is able to predict heat-transfer in a wide temperature range, from 300 up to 2000 K. • The performances of the ciliconized coatings are compared for the entry conditions of Mars Miniprobe and MSRO. The results obtained show they could be used in the thermal insulation system of the vehicle. • It is established, in particular, that using the glassy coating of the <<Buran>> orbiter tile heat shield would result in a 2.5-fold reduction in the maximum heat flux to the vehicle nose along the entire trajectory as compared with an ideal catalytic surface and in a reduction of the maximum surface temperature could be 500 K.

  28. Literature • Kovalev V.L., Afonina N.E., Gromov V.G. Catalysis Modeling for Thermal Protection Systems of Vehicles Entering into Martian Atmosphere. AIAA Paper 2001 - 2832. 2001. • Kim Y.C., Boudart M. Recombination of O, N, and H on Silica: Kinetics and Mechanism, Langmuir 1991. 7. 2999 -3005 • Gordiets B.F., Ferreira C.M. Self-consistent modelling of volume and surface processes in air plasma. AIAA Paper 97 -2504. 1997. • Daiss A., Fruhauf H.H., Messerschmid E.W. Modeling of catalytic reactions on silica surfaces with consideration of slip effects. J. Thermophysics and Heat Transfer. 1997. 11, N 3, 346-352. • Nasuti F., Barbato M., Bnmo C. Material — dependent catalytic recombination modeling for hypersonic flows. J. Thermophysics and Heat Transfer. 1996. 10. N 1. 131-136. • Bykova N.G., Vasil’evskii S.A., Gordeev A.N., Kolesnikov A.F., Pershin I.S., Yakushin M.I. Determination of the Effective Probabilities of Catalytic Reactions on the Surface of Heat Shield Materials in Dissociated Carbon Dioxide Flows, Fluid Dynamics, Vol.32(1997), No.6, pp.876-886. • Kolesnikov A.F., Pershin I.S., Vaail'evskii S.A., Jakushin M.I. Study of quartz surface catalycity in dissociated carbon dioxide subsonic flows. AIAA Paper 98-2847. 1998.

  29. Flight altitude dependence of the heat fluxes to coating I at the stagnation point for Mars Miniprobe

  30. Heat fluxes on the surface with the Langmuir-Hinshelwood recombination

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