{"project":{"acronym":"","projectId":88567,"title":"Energy Accommodation from Surface Catalyzed Reactions in Air Plasmas","primaryTaxonomyNodes":[{"taxonomyNodeId":10775,"taxonomyRootId":8816,"parentNodeId":10770,"level":3,"code":"TX09.4.5","title":"Modeling and Simulation for EDL","definition":"Modeling and simulation for EDL refers to the computer codes, underlying physical models, and processes that enable configuration definition and design verification and validation for systems that—short of a full scale flight test—cannot be tested exactly in the configuration and environment for which it is intended to operate. The models cover both the environmental response to the presence of the system in operation, and the operational performance of the system in the environment. A key concern is understanding and modeling of interactions between rocket plumes and the ground.","exampleTechnologies":"Multi-disciplinary coupled analysis tools, aerothermodynamics modeling, ablative material response models, non-ablative material response models, TPS quantification models and processes, numerical methodologies and techniques, autonomous aerobraking, orbital debris entry and breakup modeling, meteor entry and breakup modeling, Fluid Structure Interaction (FSI) tools, SRP modeling tools, aerodynamic modeling tools, plume-surface interaction, multi-scale simulation tools","hasChildren":false,"hasInteriorContent":true}],"startTrl":2,"currentTrl":3,"endTrl":3,"benefits":"This work will provide data to support improvements in numerical models of thermal protection systems (9.1.6 and 9.4.5). Impact beyond these specific areas will follow from reduction of modeling uncertainties, which will lead to lower mass margins for thermal protection, thereby providing greater scientific payload capacity.","description":"Understanding energy transport at the gas-surface interface between catalytic/reacting surfaces exposed to highly dissociated plasmas remains a significant research challenge that can critically impact the design of thermal protection systems for atmospheric entry. Physics-based models of the surface reactions and heat transfer are needed to better predict performance prior to building expensive test beds to prove material performance. However, for many practical applications multiple competing gas/surface reaction paths represent too many unknowns to easily quantify. Despite significant progress in developing better gas-phase and surface chemistry models, there is a marked lack of experimental data for validation/verification of these new models. Recent focused investigations of simple single- and dual- path surface catalyzed recombination reactions have demonstrated that measurements of reactive species fluxes arriving at the surface can be used to quantify reaction rates and recombination efficiencies. These measurements have provided useful information for physics-based gas/surface interaction model development. Unfortunately, these measurements have not answered the fundamental question of energy conservation: how much chemical energy is deposited on the surface and how much energy leaves with the recombined molecules? Species-specific chemical heating is a fundamental component of convective heat transfer to surfaces in high-enthalpy plasma flows such as those found over atmospheric entry vehicles. An experimental effort to investigate energy transport to materials in highly dissociated air plasma streams in the UVM 30 kW Inductively Coupled Plasma (ICP) Torch Facility is proposed. This effort will require the development and application of laser diagnostic strategies to quantify the energy state of the molecules leaving the surface, including rotational, vibrational, and electronic energy. Recent work has shown that NO is formed preferentially over N2 and O2 in air plasmas. Laser diagnostics for NO detection in the ICP facility have been proven, and these will be used to quantify the NO concentrations and energy distributions at the surface, and to make the balance between arriving and departing energy fluxes. Together with heat transfer measurements for the stream, these measurements will allow us to assign the amount of energy deposited by recombination. Although other surface reactions may be more important, NO represents a useful test case for laser measurements and theoretical development. The proposed research will provide unique experimental data that will fully characterize the chemical component of convective heat transfer at surfaces exposed to air plasmas. The chemical heating component is the most difficult to quantify and model. The proposed measurements of species populations, concentration gradients, and energy states will finally address energy accommodation at air plasma-surface interfaces in a species-specific and comprehensive manner. Such measurements address a critical need in NASA Technology Area 09: Entry, Descent, and Landing Systems. More specifically, this work will provide data to support improvements in numerical models of thermal protection systems (9.1.6 and 9.4.5). Impact beyond these specific areas will follow from reduction of modeling uncertainties, which will lead to lower mass margins for thermal protection, thereby providing greater scientific payload capacity.","startYear":2016,"startMonth":8,"endYear":2018,"endMonth":10,"statusDescription":"Completed","principalInvestigators":[{"contactId":128459,"canUserEdit":false,"firstName":"Douglas","lastName":"Fletcher","fullName":"Douglas G Fletcher","fullNameInverted":"Fletcher, Douglas G","middleInitial":"G","primaryEmail":"douglas.fletcher@uvm.edu","publicEmail":false,"nacontact":false}],"programDirectors":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programExecutives":[{"contactId":84634,"canUserEdit":false,"firstName":"Claudia","lastName":"Meyer","fullName":"Claudia M Meyer","fullNameInverted":"Meyer, Claudia M","middleInitial":"M","primaryEmail":"claudia.m.meyer@nasa.gov","publicEmail":true,"nacontact":false}],"programManagers":[{"contactId":183514,"canUserEdit":false,"firstName":"Hung","lastName":"Nguyen","fullName":"Hung D Nguyen","fullNameInverted":"Nguyen, Hung D","middleInitial":"D","primaryEmail":"hung.d.nguyen@nasa.gov","publicEmail":true,"nacontact":false}],"projectManagers":[{"contactId":368183,"canUserEdit":false,"firstName":"Paul","lastName":"Danehy","fullName":"Paul M Danehy","fullNameInverted":"Danehy, Paul M","middleInitial":"M","primaryEmail":"paul.m.danehy@nasa.gov","publicEmail":true,"nacontact":false}],"coInvestigators":[{"contactId":409854,"canUserEdit":false,"firstName":"Roland","lastName":"Herrmann-Stanzel","fullName":"Roland Herrmann-stanzel","fullNameInverted":"Herrmann-Stanzel, Roland","primaryEmail":"rstanzel@gmail.com","publicEmail":false,"nacontact":false}],"website":"","libraryItems":[],"transitions":[{"transitionId":75933,"projectId":88567,"transitionDate":"2018-10-01","path":"Closed Out","details":"Accurate knowledge of heat transfer to materials in recombining plasmas is needed to improve heat shield designs. A lack of understanding of the chemical component of surface heating motivates the use of conservative assumptions with regards to surface catalysis in the design of thermal protection systems (TPS) that detrimentally impact payload capability. Chemical heating is the release of potential energy from recombining reactive species on the surface to form molecules. For a stable surface interacting with partially-dissociated air, the chemical heating component is due to surface-catalyzed recombination reactions of atomic O and N to produce molecular O2, N2, and NO. Unfortunately, heat flux measurements provide no fundamental information about the surface recombination pathways involved, or how the energy reaches the surface. Rather, they give a total heating rate. This work advances the current limited understanding about the chemical energy transport to and from material surfaces in high-temperature, recombining plasmas. A combination of spatially resolved laser-based diagnostics and emission spectroscopy was used to measure the number densities (relative and absolute) and gradients of the reactants (N, O), the products (NO, N2) and the energy distribution of recombined molecules (NO, N2) in the boundary layer adjacent to a plasma heated material. Laser excitation probes individual species by electronic state (atoms) and by electronic, vibrational and rotational states (molecules). Emission spectroscopy provides spectrally resolved intensities of transitions for a range of species and electronic, vibrational and rotational states of both atoms and molecules. These measurements of spatial variations in species concentrations through the boundary layer are directly related to near-surface gas-phase chemistry and energy exchange and have provided experimental information that was not previously available. Results provide insight into the energy deposited on the surface due to surface catalyzed recombination of atomic nitrogen and oxygen in air plasma.","infoText":"Closed out","infoTextExtra":"","dateText":"October 2018"}],"responsibleMd":{"acronym":"STMD","canUserEdit":false,"city":"","external":false,"linkCount":0,"organizationId":4875,"organizationName":"Space Technology Mission Directorate","organizationType":"NASA_Mission_Directorate","naorganization":false,"organizationTypePretty":"NASA Mission Directorate"},"program":{"acronym":"STRG","active":true,"description":"
\tThe Space Technology Research Grants Program will accelerate the development of "push" technologies to support the future space science and exploration needs of NASA, other government agencies and the commercial space sector. Innovative efforts with high risk and high payoff will be encouraged. The program is composed of two competitively awarded components.
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