Experimental and Numerical Simulation of Martian Entry Conditions

Experimental and Numerical Simulation of Martian Entry Conditions Kovalev R. V. *, Gorshkov A. B. , Rudin N. F. , Vlasov V. I. , Zalogin G. N. Central Research Institute for Machine Building (Ts. NIImash, Russia) *e-mail: kovalevrv@mail. ru IPPW-9, Toulouse, France, 18 -22 June, 2012

Outline 1. 2. 3. 4. Work motivation and objectives Test campaign CFD rebuilding of tests Conclusions IPPW-9, Toulouse, France, 18 -22 June, 2012

Work motivation and objectives(1) Work objectives 1. Experimental and numerical study of gas-surface interaction phenomena in the high enthalpy flow field behind the bow shock in front of a model at Martian entry flow conditions 2. Improvement of Mars atmosphere (97%CO 2) thermochemical model at high enthalpies 3. Obtaining new experimental data on physical and chemical behavior of Mars atmosphere species under highenthalpy flow conditions Reference points of the Exo. Mars trajectory used for experimental modeling in U-13 facility. Trajectory Time Velocity Enthalpy Pitot point pressure [sec] [m/sec] [MJ/kg] [h. Pa] number 1 81 5228 13. 8 55 2 104 4072 8. 5 82 IPPW-9, Toulouse, France, 18 -22 June, 2012

U-13 ICP facility RF Generator Model input device Exhaust system diffuser ICP heater Gas supply chamber Vacuum pumping Data acquisition IPPW-9, Toulouse, France, 18 -22 June, 2012 4

Test matrix for U-13 ICP facility Test condition FC 1 FC 2 Enthalpy Pitot pressure [MJ/kg] [h. Pa] Sample materials 10, 20, 40, 80 Silver, Quartz, Copper 13. 8 9 IPPW-9, Toulouse, France, 18 -22 June, 2012 5

Test model flow Silver calorimeter Quartz calorimeter IPPW-9, Toulouse, France, 18 -22 June, 2012 Copper calorimeter 6

Test model(2) IPPW-9, Toulouse, France, 18 -22 June, 2012 7

CO 2+N 2 mixture flow diagnostics in U-13 ICP facility (O+O(s)) = 0. 025 (CO+O(s)) = 0. 05 Heat flux to silver calorimetric probe vs. anode power Total enthalpy vs. anode power IPPW-9, Toulouse, France, 18 -22 June, 2012 8

CO 2+N 2 mixture flow diagnostics in U-13 ICP facility (2) P, h. Pa IPPW-9, Toulouse, France, 18 -22 June, 2012 H, MJ/kg T, K Line form T, K Abs 10 13. 8 3000 OH(A) 20 13. 8 4000 CN(B) 38004400 CN(A, B) NO, O 40 13. 8 4500 CN(B) 38004400 CN(A, B) NO, O 80 13. 8 5000 CN(B) 45005000 CN(A, B) NO, O 40 9 3000 O 2(SR) 80 9 3000 O 2(SR) 9

Test results IPPW-9, Toulouse, France, 18 -22 June, 2012 10

Test results Temperature distribution, t=1. 2 s P=20 mbar, N=125 k. W Heat flux distribution IPPW-9, Toulouse, France, 18 -22 June, 2012 11

Governing equations Continuity Momentum conservation IPPW-9, Toulouse, France, 18 -22 June, 2012

Governing equations Energy conservation Species continuity IPPW-9, Toulouse, France, 18 -22 June, 2012

Maxwell equations • Sine-wave EM-field (with frequency ω) : • Ohm law • Inductor field: • Total EM-field E is decomposed to the inductor (E 0) and plasma fields e = e 1 + ie 2 E = E 0 + e IPPW-9, Toulouse, France, 18 -22 June, 2012

• Lorentz force in motion equations • Joule heating in energy equation • Either inductor current or energy input to plasma is imposed e 1 = e 2 + E 0 = 0 E, V/cm e 1 = e 2 = 0 I, A/cm 2 IPPW-9, Toulouse, France, 18 -22 June, 2012

Thermochemical model • CO 2+N 2 plasma (O 2, CO, O, C, CO+, NO+, C+, N+, e–, N 2, N, NO, CN) • Reaction set O 2 + M 1 = O + M 1 CO 2 + M 2 = CO + M 3 = C + O + M 2 O + CO = O 2 + C O + CO 2 = O 2 + CO O + C = CO+ + e– O + e– = O + + e– C + e– = C + + e– N 2 + M 4 = N + M 4 NO + M 5 = N + O + M 5 CN + M 6 = N + C + M 6 O + NO = O 2 + N N + NO = N 2 + O O + N = NO+ + e– N + e– = N + + e– CN + O = NO + C • 1 -temperature assumption ( Trot = Tvib = Te = Ttransl ), 2 -temperature assumption ( Trot = Ttransl , Tvib = Te) • Modified Fick’s law (with account for ambipolar diffusion) - SCBD IPPW-9, Toulouse, France, 18 -22 June, 2012

Thermochemical model • Surface heterogeneous catalysis • Surface reactions O(g) ↔ (O-S) O(g) + (O-S) → O 2(g) CO(g) + (O-S) → CO 2(g) γads γO γCO Relative heat flux depending on recombination probabilities at P = 20 h. Pa, H 0 = 17 MJ/kg γads= 0. 2 IPPW-9, Toulouse, France, 18 -22 June, 2012

Results of CFD test rebuilding Temperature distribution within the discharge chamber , P=20 h. Pa, H=13. 5 MJ/kg Temperature distribution in plasma jet near the model IPPW-9, Toulouse, France, 18 -22 June, 2012 18

Results of CFD test rebuilding Experimental and numerical heat fluxes vs. input power at P = 20 h. Pa IPPW-9, Toulouse, France, 18 -22 June, 2012 Experimental and numerical Pitot pressure vs. input power at P = 20 h. Pa

Conclusions üA number of tests intended to investigate and improve thermochemical model of Martian atmosphere were performed in the U-13 ICP facility of Ts. NIImash. Measurements were made for two reference values of free stream enthalpy – 9 and 13. 8 MJ/kg and four pressures – 10, 20, 40 and 80 h. Pa; üHeat fluxes to the silver, copper and quartz materials were measured; üHeat fluxes to the quartz surface is about 50% lower than to metallic surfaces; üHeat flux to the copper surface is only slightly lower than to the silver one; üStandard diagnostic procedure of ICP flow suitable for air flow conditions turns to be much more complicated and dependent on thermochemical model for the case of CO 2; üNumerical rebuilding of the tests performed is in progress; üPreliminary results of CFD modelling demonstrates that silver (at least electrolysis coated) cannot be referred as fully catalytic material for CO 2+N 2 mixture species recombination for the test conditions; IPPW-9, Toulouse, France, 18 -22 June, 2012