Institute of Mechanics Lomonosov Moscow State University Institute for Problems in Mechanics of Russian Academy of Sciences

Transcription

1 Institute of Mechanics Lomonosov Moscow State University Institute for Problems in Mechanics of Russian Academy of Sciences HEAT TRANSFER IN UNDER-EXPANDED NON-EQUILIBRIUM CARBON DIOXIDE JETS: AN EXPERIMENT IN RF-PLASMA TORCH AND EXTRAPOLATION TO MARTIAN ATMOSPHERE ENTRY CONDITIONS V.I. Sakharov, A.F. Kolesnikov and A.N. Gordeev 8 th European Symposium on Aerothermodynamics for Space Vehicles 2 6 March 2015 IST Congress Centre, Lisbon, Portugal 1

2 Outline 1. The experimental and calculated data on heat transfer in under-expanded jets dissociated carbon dioxide 2. Extrapolation of the experimental conditions on the RF plasma torch to the Mars entry conditions 3. Parameters similar at the plasmatron test and hypersonic flow past a sphere in the Martian atmosphere 4. Conclusions 8-th ESASV 2-6 March

3 РОССИЙСКАЯ 100-kW RF-PLASMOTRON IPG-4 АКАДЕМИЯ НАУК

4 High-frequency induction discharge in a stream of carbon dioxide in the IPG- 4 plasma torch 8-th ESASV 2-6 March

5 Subsonic high-enthalpy CO 2 flow 8-th ESASV 2-6 March

6 Supersonic under-expanded jets in the IPG-4 plasmatron Air CO2 8-th ESASV 2-6 March 2015

7 Model in under-expanded plasma jet Air CO2 8-th ESASV 2-6 March 2015

8 Numerical simulation The quasi time-dependent 3-D Navier-Stokes equations are solved on the multiblock structured mesh through a finite volume approach The simplified quasi 1-D Maxwell equation for the RF electromagnetic field are added to the N-S equations in the discharge channel Parameters of the problem: the parameters of the injected gas, pressure in the chamber, the value of the energy input into the plasma the multi-block grid 8-th ESASV 2-6 March

9 Boundary conditions on the solid surfaces - zero flow velocity, the surface temperature is specified (T = Tw) on the channel axis - symmetry conditions outflow boundary - non-reflective boundary conditions on the surface of the model - recombination coefficients for carbon atoms, carbon monoxide and oxygen atoms at the inlet section - gas flow and swirl flow parameters, zero pressure gradient 8-th ESASV 2-6 March

10 The gas medium models the 11 th species CO 2 model with chemical components: O, C, O 2, CO 2, CO, C 2, O +, C +, O 2+, CO +, e - Thermal model: Rotational and vibrational energy modes of molecules are described by the rigid rotator harmonic oscillator model with the Boltzmann distribution of the energy levels. 1TM - one-temperature thermally equilibrium model: T =T v =T e 3TM - three-temperature model: T T ν T e molecules are characterised by common vibrational temperature T v electron temperature T e is calculated from the electron gas energy balance equation 8-th ESASV 2-6 Marсh

11 Temperature and flow fields in the IPG-4 torch for CO 2 plasma CO 2 : G=4.6 g/s; N ap = 53 kw; D s = 30 mm 8-th ESASV 2-6 March

12 Isobars in CO2 plasma flow around a model Z m = 40 mm Z m = 70 mm CO 2 : G = 4.6 g/s; N ap = 53 kw; p = 10.4 hpa; D s = 30mm 8-th ESASV 2-6 Marсh

13 Stagnation pressure as function of distance from the plasmatron exit section at carbon dioxide mass flow rate 4.6 g/s N=64kW N=53kW N=45kW 50 Pst, hpa Z, mm Comparison of calculated and experimental data 8-th ESASV 2-6 Marсh

14 Comparison calculated and experimental stagnation point heat fluxes at carbon dioxide mass flow rate 3.0 g/s and generator anode power 45, 53, 64 kw q, W/cm Z, mm Comparison of calculated and experimental data 8-th ESASV 2-6 March

15 Correlations between parameters of the experiment and entry conditions LHTS Concept, A. Kolesnikov, AIAA V H = = 2 Hse0 2 p V p 2 w0 = ρ = m0 1/2 8 ρ V Us 3 ρ sh R = w r e0 q wcat = q mcat 8-th ESASV 2-6 March

16 Parameters of supersonic flow around a 20-mm diameter cylindrical watercooled model for the three IPG-4 test regimes regimes G, g/s N ap, kw V S, m/s H se0, МДж/kg T S, K ρ S, kg/m 3 p m0, Н/m 2 (du S /dr) e0 s -1 P P P Conditions of hypersonic carbon dioxide flows around a sphere regimes H, МДж/kg V, m/s ρ, kg/m 3 T, K R w, cm E E E th ESASV 2-6 March

17 Flows around a sphere in Martian atmosphere and near the model in plasmatron 8-th ESASV 2-6 March

18 Stagnation line pressure (a) and temperature (b) as functions of the distance from the body surface and plasmatron exit section distance for regimes P1 and E1 40 P,hPa а) 1 - sphere Rw = 5,2 cm 2 - plasmatron, Zm = 3 cm T, K b) 1 - sphere Rw = 5,2 cm 2 - plasmatron, Zm = 3 cm Z, cm 3 Stagnation line pressure Z, cm 3 Stagnation line temperature 8-th ESASV 2-6 March

19 Normalized stagnation point heat fluxes to cold wall (a) and equilibrium radiative wall (b) in P1 plasmatron and E1 entry flow regimes q*=(q-q 0 )/(q - q 0 ) 1 1 q W * a) sphere, Rw = 5.2 cm model, Zm= 3 cm q W * b) sphere, Rw = 5.2 cm model, Zm= 3 cm x x x10-1 γ 1.0x10 0 Cold wall 0 1.0x x x10-1 γ 1.0x10 0 Equilibrium radiative wall 8-th ESASV 2-6 March

20 Extrapolation of the heat flux from plasmatron test to entry conditions A. Kolesnikov, AIAA q q q q q q f f f ( e e ) w w0 f w = w w0 e e + w0 qw qw0 e experiment f hypersonic flow fully catalytic wall 0 non-catalytic wall 8-th ESASV 2-6 March

21 Conclusions 1.Good agreement in terms of experimental data and numerical results for stagnation pressure and heat transfer rates to cooled copper surface of the 20-mm diameter cylindrical model located in under-expanded dissociated carbon dioxide jets before Mach disc is achieved. 2. Normalized stagnation point heat fluxes as functions of effective coefficient γ in terms of catalytic recombination of O and CO are similar, when the IPG-4 plasmatron tests and the Mars entry conditions are connected on the base of the LHTS Concept. 8-th ESASV 2-6 March

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