Plan Nonequilibrium Processes and Plasma Radiation in Hyperbolic Atmospheric Entry Flows M. Lino da Silva, V. Guerra, J. Loureiro (1) Centro de F ´ isica de Plasmas, Instituto Superior T´ ecnico, Lisboa, Portugal 3 August 2005 M´ ario Lino da Silva Nonequilibrium Processes & Plasma Radiation
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Plan
Nonequilibrium Processes and Plasma Radiation inHyperbolic Atmospheric Entry Flows
M. Lino da Silva, V. Guerra, J. Loureiro
(1) Centro de Fisica de Plasmas, Instituto Superior Tecnico, Lisboa, Portugal
3 August 2005
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Plan
Plan
1 Physical-Chemical-Radiative Problems of HyperbolicAtmospheric Entries
2 Example for Radiative Calculations: Mars Atmospheric Entries
3 Nonequilibrium Excitation Processes in Shock-Heated EntryFlows
4 Concluding Remarks and Perspectives
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Plan
Plan
1 Physical-Chemical-Radiative Problems of HyperbolicAtmospheric Entries
2 Example for Radiative Calculations: Mars Atmospheric Entries
3 Nonequilibrium Excitation Processes in Shock-Heated EntryFlows
4 Concluding Remarks and Perspectives
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Plan
Plan
1 Physical-Chemical-Radiative Problems of HyperbolicAtmospheric Entries
2 Example for Radiative Calculations: Mars Atmospheric Entries
3 Nonequilibrium Excitation Processes in Shock-Heated EntryFlows
4 Concluding Remarks and Perspectives
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Plan
Plan
1 Physical-Chemical-Radiative Problems of HyperbolicAtmospheric Entries
2 Example for Radiative Calculations: Mars Atmospheric Entries
3 Nonequilibrium Excitation Processes in Shock-Heated EntryFlows
4 Concluding Remarks and Perspectives
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Spacecraft Atmospheric Entries from Outer Space
Hyperbolic entry trajectories at v > 10km/s (From Mars v = 11 km/s).Space-Shuttle entries from orbit(parabolic trajectory) at v < 7 km/s.Plasma radiation important for overallheat fluxes calculation at v > 5 km/sExtreme nonequilibrium conditionsbehind the strong shock-wave,Ttr � Tvib, Ttr > 10, 000 K
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Spacecraft Atmospheric Entries from Outer Space
Hyperbolic entry trajectories at v > 10km/s (From Mars v = 11 km/s).Space-Shuttle entries from orbit(parabolic trajectory) at v < 7 km/s.Plasma radiation important for overallheat fluxes calculation at v > 5 km/sExtreme nonequilibrium conditionsbehind the strong shock-wave,Ttr � Tvib, Ttr > 10, 000 K
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Spacecraft Atmospheric Entries from Outer Space
Hyperbolic entry trajectories at v > 10km/s (From Mars v = 11 km/s).Space-Shuttle entries from orbit(parabolic trajectory) at v < 7 km/s.Plasma radiation important for overallheat fluxes calculation at v > 5 km/sExtreme nonequilibrium conditionsbehind the strong shock-wave,Ttr � Tvib, Ttr > 10, 000 K
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Estimation of the Spacecraft Aerodynamic and Thermal(Convective + Radiative) Loads
Gas radiative properties determined by thewavelength-dependent emission and absorption coefficients:
εul = NuAul∆Eul
αlu = NlBlu∆Eul
Besides the transition radiative properties (Aul ,Blu), the statepopulations need to be known (Nu,Nl), usually in astate-to-state approach
Dissociation (endothermic) and recombination (exotermic)chemical reactions affect convective heating loads and alsoneed to be treated in the state-to-state approach
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Estimation of the Spacecraft Aerodynamic and Thermal(Convective + Radiative) Loads
Gas radiative properties determined by thewavelength-dependent emission and absorption coefficients:
εul = NuAul∆Eul
αlu = NlBlu∆Eul
Besides the transition radiative properties (Aul ,Blu), the statepopulations need to be known (Nu,Nl), usually in astate-to-state approach
Dissociation (endothermic) and recombination (exotermic)chemical reactions affect convective heating loads and alsoneed to be treated in the state-to-state approach
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Estimation of the Spacecraft Aerodynamic and Thermal(Convective + Radiative) Loads
Gas radiative properties determined by thewavelength-dependent emission and absorption coefficients:
εul = NuAul∆Eul
αlu = NlBlu∆Eul
Besides the transition radiative properties (Aul ,Blu), the statepopulations need to be known (Nu,Nl), usually in astate-to-state approach
Dissociation (endothermic) and recombination (exotermic)chemical reactions affect convective heating loads and alsoneed to be treated in the state-to-state approach
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Estimation of the Spacecraft Aerodynamic and Thermal(Convective + Radiative) Loads
Gas radiative properties determined by thewavelength-dependent emission and absorption coefficients:
εul = NuAul∆Eul
αlu = NlBlu∆Eul
Besides the transition radiative properties (Aul ,Blu), the statepopulations need to be known (Nu,Nl), usually in astate-to-state approach
Dissociation (endothermic) and recombination (exotermic)chemical reactions affect convective heating loads and alsoneed to be treated in the state-to-state approach
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Estimation of the Spacecraft Aerodynamic and Thermal(Convective + Radiative) Loads
Gas radiative properties determined by thewavelength-dependent emission and absorption coefficients:
εul = NuAul∆Eul
αlu = NlBlu∆Eul
Besides the transition radiative properties (Aul ,Blu), the statepopulations need to be known (Nu,Nl), usually in astate-to-state approach
Dissociation (endothermic) and recombination (exotermic)chemical reactions affect convective heating loads and alsoneed to be treated in the state-to-state approach
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Simulation of Atmospheric Entry Radiation
Two different issues: calculation of transition probabilities(quantum mechanics models) and calculation of quantumstates populations (collisional-radiative models)
Calculation of transition probabilities can now be routinelycarried for most chemical species
No complete collisional-radiative model exists for thesimulation of atmospheric entry flows. Most simulationsassume Boltzmann equilibrium conditions
Additional issue (not discussed here): radiation transport →different numerical models available
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Simulation of Atmospheric Entry Radiation
Two different issues: calculation of transition probabilities(quantum mechanics models) and calculation of quantumstates populations (collisional-radiative models)
Calculation of transition probabilities can now be routinelycarried for most chemical species
No complete collisional-radiative model exists for thesimulation of atmospheric entry flows. Most simulationsassume Boltzmann equilibrium conditions
Additional issue (not discussed here): radiation transport →different numerical models available
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Simulation of Atmospheric Entry Radiation
Two different issues: calculation of transition probabilities(quantum mechanics models) and calculation of quantumstates populations (collisional-radiative models)
Calculation of transition probabilities can now be routinelycarried for most chemical species
No complete collisional-radiative model exists for thesimulation of atmospheric entry flows. Most simulationsassume Boltzmann equilibrium conditions
Additional issue (not discussed here): radiation transport →different numerical models available
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Simulation of Atmospheric Entry Radiation
Two different issues: calculation of transition probabilities(quantum mechanics models) and calculation of quantumstates populations (collisional-radiative models)
Calculation of transition probabilities can now be routinelycarried for most chemical species
No complete collisional-radiative model exists for thesimulation of atmospheric entry flows. Most simulationsassume Boltzmann equilibrium conditions
Additional issue (not discussed here): radiation transport →different numerical models available
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Atmospheric Entry Radiation Research Activities at IST
Line-by-Line numerical code SPARTAN: Simulation ofPlasmA Radiation in ThermodynAmic Nonequilibrium
63 atomic and molecular bound-bond, bound-free(Photodissociation, Photoionization, Photodetachment), andfree-free (Bremsstrahlung) transitions from C, N, and Ocontaining species (Earth & Mars)
Online Gas & Plasma Radiation Database (GPRD) athttp://cfp.ist.utl.pt/radiation for providing the scientificcommunity with a database for molecular radiation
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Atmospheric Entry Radiation Research Activities at IST
Line-by-Line numerical code SPARTAN: Simulation ofPlasmA Radiation in ThermodynAmic Nonequilibrium
63 atomic and molecular bound-bond, bound-free(Photodissociation, Photoionization, Photodetachment), andfree-free (Bremsstrahlung) transitions from C, N, and Ocontaining species (Earth & Mars)
Online Gas & Plasma Radiation Database (GPRD) athttp://cfp.ist.utl.pt/radiation for providing the scientificcommunity with a database for molecular radiation
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Atmospheric Entry Radiation Research Activities at IST
Line-by-Line numerical code SPARTAN: Simulation ofPlasmA Radiation in ThermodynAmic Nonequilibrium
63 atomic and molecular bound-bond, bound-free(Photodissociation, Photoionization, Photodetachment), andfree-free (Bremsstrahlung) transitions from C, N, and Ocontaining species (Earth & Mars)
Online Gas & Plasma Radiation Database (GPRD) athttp://cfp.ist.utl.pt/radiation for providing the scientificcommunity with a database for molecular radiation
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Spectral Simulation of the Equilibrium Radiative Propertiesof a Martian-Type Plasma
High resolution calculation of emission and absorptioncoefficients for a 100A–100µm spectral range at 1000, 5000,and 10000 K using the full spectroscopic database (49transitions)
30 min calculation time on a laptop for a spectrum of∼ 105 − 106 points
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Spectral Simulation of the Equilibrium Radiative Propertiesof a Martian-Type Plasma
High resolution calculation of emission and absorptioncoefficients for a 100A–100µm spectral range at 1000, 5000,and 10000 K using the full spectroscopic database (49transitions)
30 min calculation time on a laptop for a spectrum of∼ 105 − 106 points
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Selection of an Appropriate Spectral Database
For equilibrium conditions, few atomic and molecular systemscontribute for overall radiative flux
Not to be extrapolated to nonequilibrium conditions! (evenfor Boltzmann equilibrium of the flow, e.g. C2 Swan Bands).Also for non-optically thin gas must account for absorbingtransitions, e. g. O2 Schumann–Runge
Must have the most reduced set without losing precision(lower number of calculated lines)
More difficult task in strong nonequilibrium conditions! (e. g.behind shock-waves)
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Selection of an Appropriate Spectral Database
For equilibrium conditions, few atomic and molecular systemscontribute for overall radiative flux
Not to be extrapolated to nonequilibrium conditions! (evenfor Boltzmann equilibrium of the flow, e.g. C2 Swan Bands).Also for non-optically thin gas must account for absorbingtransitions, e. g. O2 Schumann–Runge
Must have the most reduced set without losing precision(lower number of calculated lines)
More difficult task in strong nonequilibrium conditions! (e. g.behind shock-waves)
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Selection of an Appropriate Spectral Database
For equilibrium conditions, few atomic and molecular systemscontribute for overall radiative flux
Not to be extrapolated to nonequilibrium conditions! (evenfor Boltzmann equilibrium of the flow, e.g. C2 Swan Bands).Also for non-optically thin gas must account for absorbingtransitions, e. g. O2 Schumann–Runge
Must have the most reduced set without losing precision(lower number of calculated lines)
More difficult task in strong nonequilibrium conditions! (e. g.behind shock-waves)
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Selection of an Appropriate Spectral Database
For equilibrium conditions, few atomic and molecular systemscontribute for overall radiative flux
Not to be extrapolated to nonequilibrium conditions! (evenfor Boltzmann equilibrium of the flow, e.g. C2 Swan Bands).Also for non-optically thin gas must account for absorbingtransitions, e. g. O2 Schumann–Runge
Must have the most reduced set without losing precision(lower number of calculated lines)
More difficult task in strong nonequilibrium conditions! (e. g.behind shock-waves)
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Reproduction of Inflight Flow Conditions in Ground-TestFacilities
Shock-tube facilities typical offorebody flows, closer to entryflow conditions (Etr > Eel) butshort test times (<1 ms) andtypically with v<10 km/sPlasma facilities typical ofafterbody flows and fartherfrom entry flow conditions(Etr < Eel) but virtuallyunlimited test times
Simulation of entry-like flows in different ground-testfacilities
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Reproduction of Inflight Flow Conditions in Ground-TestFacilities
Shock-tube facilities typical offorebody flows, closer to entryflow conditions (Etr > Eel) butshort test times (<1 ms) andtypically with v<10 km/sPlasma facilities typical ofafterbody flows and fartherfrom entry flow conditions(Etr < Eel) but virtuallyunlimited test times
Simulation of entry-like flows in different ground-testfacilities
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Evolution of the Molecular Dissociation at Different ShockTemperatures
Dissociation times range frommore than 1 s for T ≤ 5, 000Kto 1 ns for T = 100, 000KFor lower temperatures,“ladder-climbing” phenomenaenhance dissociation after acertain incubation time
At higher temperatures,(T ≥ 50, 000K) dissociationproceeds equiprobably from allthe vibrational levels
Time evolution of N2 dissociation at different shocktemperatures
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Evolution of the Molecular Dissociation at Different ShockTemperatures
Dissociation times range frommore than 1 s for T ≤ 5, 000Kto 1 ns for T = 100, 000KFor lower temperatures,“ladder-climbing” phenomenaenhance dissociation after acertain incubation time
At higher temperatures,(T ≥ 50, 000K) dissociationproceeds equiprobably from allthe vibrational levels
Time evolution of N2 dissociation at different shocktemperatures
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Evolution of the Molecular Dissociation at Different ShockTemperatures
Dissociation times range frommore than 1 s for T ≤ 5, 000Kto 1 ns for T = 100, 000KFor lower temperatures,“ladder-climbing” phenomenaenhance dissociation after acertain incubation time
At higher temperatures,(T ≥ 50, 000K) dissociationproceeds equiprobably from allthe vibrational levels
Time evolution of N2 dissociation at different shocktemperatures
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Conclusions
Development of radiation databases is a straightforward task,but needs extensive validations
Developed state-to-state models need to be valid for the mostextreme hyperbolic shock-waves. Importance of multiquantumtransitions
Computation time issues remain determinant as they preventfull-use of line-by-line calculations and state-to-state models.The errors induced by the used approximations (Boltzmannequilibrium, band models) remain unknown
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Conclusions
Development of radiation databases is a straightforward task,but needs extensive validations
Developed state-to-state models need to be valid for the mostextreme hyperbolic shock-waves. Importance of multiquantumtransitions
Computation time issues remain determinant as they preventfull-use of line-by-line calculations and state-to-state models.The errors induced by the used approximations (Boltzmannequilibrium, band models) remain unknown
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Conclusions
Development of radiation databases is a straightforward task,but needs extensive validations
Developed state-to-state models need to be valid for the mostextreme hyperbolic shock-waves. Importance of multiquantumtransitions
Computation time issues remain determinant as they preventfull-use of line-by-line calculations and state-to-state models.The errors induced by the used approximations (Boltzmannequilibrium, band models) remain unknown
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Perspectives
V–T dissociation models should include effects of molecularrotation
V–E processes need more theoretical developments. Onlyavailable experimental data obtained for gas-dischargeapplications with Ttr ∼ 300KRadiation re-absorption may be important for hyperbolic flows(see Park 2004 for Galileo probe entry simulations)
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Perspectives
V–T dissociation models should include effects of molecularrotation
V–E processes need more theoretical developments. Onlyavailable experimental data obtained for gas-dischargeapplications with Ttr ∼ 300KRadiation re-absorption may be important for hyperbolic flows(see Park 2004 for Galileo probe entry simulations)
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation
Nonequilibrium Processes in Shock-Heated FlowsConclusions & Perspectives
Perspectives
V–T dissociation models should include effects of molecularrotation
V–E processes need more theoretical developments. Onlyavailable experimental data obtained for gas-dischargeapplications with Ttr ∼ 300KRadiation re-absorption may be important for hyperbolic flows(see Park 2004 for Galileo probe entry simulations)
Mario Lino da Silva Nonequilibrium Processes & Plasma Radiation