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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

USM3D-ME Analyses Performed in Support of a Wind Tunnel Test of a Boundary-Layer Ingestion Configuration

Boundary Layer Ingestion (BLI) has been proposed as a technology with the potential to decrease fuel burn. However, one major concern for BLI configurations is the potential degradation of the flow quality, both on the airframe and at the fan face, resulting from the tightly integrated propulsor. A wind tunnel test was performed in the National Transonic Facility (NTF) at the NASA Langley Research Center to investigate the flow quality ingested by a tail cone thruster configuration, similar to the Single Aisle Turboelectric Aircraft Concept with Aft Boundary Layer Ingestion (STARC-ABL). The wind tunnel model was a modified version of the Common Research Model (CRM) to include an aft-mounted, flow-through propulsor. The experimental data obtained from the wind tunnel test provide insight into the flow and enables an assessment of the accuracy of the USM3D-ME flow solver for predicting the flow at the fan face, which will be crucial for fan design purposes. Both grid refinement and turbulence model studies were performed for the Clean and Cruise MFP configurations at the condition corresponding to ReMAC = 5 million, Mach = 0.8, and alpha = 2 deg. The selected grid refinement level and turbulence model were then used to perform simulations over the range of conditions considered in the NTF wind tunnel test. The condition sweep comparisons illustrate favorable agreement with the experimental data over the entire range of conditions and for all Mass Flow Plug (MFP) configurations. The largest differences were observed for the Idle MFP configuration, with approximately 3% difference observed between USM3D-ME and the experimental data. Future work should investigate the impact of higher fidelity turbulence models and grid adaptation on the USM3D-ME predictions.

CRM↗
NASA NTRSDate not supplied

NASA Contributions to the High Lift Common Research Model Ecosystem

As part of the High Lift Common Research Model (CRM-HL) ecosystem, NASA has designed and built two CRM-HL models. The first model is a 5.2% scale semispan model that has been tested in the NASA Langley 14- by 22-Foot Subsonic Wind Tunnel (14x22), the low-speed wind tunnel DNW-NWB in Germany and in the National Transonic Facility (NTF) at NASA Langley Research Center. Information on the NASA tests that will include model details, test methods and some test data will be presented in the final document. The second model is a 2.7% scale model that will also be tested in the NTF in both full span and semispan configurations. Information on the design and fabrication of this model will be included in the final document.

Melissa Rivers↗
NASA NTRSDate not supplied

Computational Analysis of a Boundary Layer Ingesting Tailcone Thruster Configuration Using the LAVA Curvilinear Solver

Boundary layer ingesting (BLI) propulsion systems are one of the many technologies currently under investigation within the aerospace community to meet NASA's Advanced Air Transport Technology project goal of a sustainable future in aviation. To that end, an experimental campaign was conducted in the National Transonic Facility (NTF) wind tunnel to study the propulsion-airframe integration effects of the Boundary Layer Ingesting Tailcone System installed in the aft portion of a 2.7% scale design of the NASA Common Research Model (CRM). This test was accompanied by a numerical simulation effort using the Launch, Ascent, and Vehicle Aerodynamics (LAVA) curvilinear solver to validate the applicability of current best-practice Reynolds-Averaged Navier-Stokes (RANS) models in accurately predicting the relevant flow physics in free-air. A total of 205 steady RANS simulations were performed using LAVA, covering the range of conditions present in the NTF test matrix. Flow conditions ranged from 5- to 15-million Reynolds number, Mach numbers of 0.75, 0.80 and 0.85, and angles of attack between -3 and 4 degrees. Four different mass-flow plugs were also tested to assess propulsor operating condition effects. Sensitivity to these flow conditions is analyzed in detail, especially in terms of the nacelle flow distortion which was the main subject of the study. Aerodynamic load coefficients, aft body boundary layer measurements and fuselage pressure tap results are also discussed, providing a wide range of validation results from this experimental campaign. This validation effort shows that current best-practices using RANS models within the LAVA curvilinear solver flow solver are well suited for predicting the inlet flow distortion characteristics of novel aircraft configurations employing BLI at the aft end of the fuselage. This talk will cover the combined experimental and numerical efforts that resulted from this BLI-focused investigation.

ARMD↗
NASA NTRSDate not supplied

Reynolds Number Effects on a 5.2%-Scale High Lift Common Research Model

A 5.2%-scale High Lift Common Research Model (CRM-HL) semispan wind tunnel model was tested at the National Transonic Facility (NTF) wind tunnel in Hampton, VA. One of the primary objectives of the NTF test was to determine the effect of varying Reynolds number on the configuration. The test used a combination of air and cryogenic nitrogen testing to obtain up to flight-like Reynolds numbers. The landing and takeoff configurations of the model were tested at speeds ranging from Mach 0.2 to 0.35. The Reynolds numbers based on the mean aerodynamic chord of the model ranged from 1.6 to 30 million. Overall, the lift increased and drag decreased with increasing Reynolds number for chord Reynolds numbers less than 16 million, following well-established trends. However, some anomalies in the force and moment data were observed in the linear region of the angle of attack range that did not follow expected trends. The force and moment results for both the landing and takeoff configurations are presented, along with surface pressure data for the landing configuration. Incremental effects from the landing gear, nacelle, and horizontal tail on the landing configuration are also presented.

CRM-HL↗
NASA NTRSDate not supplied

Transition Measurements on the SWiFT Model in the National Transonic Facility

Boundary layer transition locations on the Swept Wing Flow Test (SWiFT) Hybrid Wing Body model were measured in the National Transonic Facility (NTF) at the NASA Langley Research Center using several different methods. These methods include sublimating chemical flow visualization for a limited number of low Reynolds number conditions, as well as mean static pressure and dynamic pressure measurements. Results are presented for a range of conditions in the NTF, demonstrating Mach and Reynolds number effects. The transition front locations obtained from the different techniques agree well. A variation of the static pressure transition detection method is described in which continuous angle of attack polars are performed. This approach enables detection of the transition front at more challenging (high Reynolds number) conditions than is possible with sparser data from pitch-pause angle-of-attack polars. The trip dot effectiveness is also verified using all of the available diagnostics. Additionally, low Reynolds number results are compared with those acquired on the same model at the Aircraft Research Association (ARA) facility, and these results show good agreement overall, suggesting similar freestream flow quality conditions of the two facilities.

National Transonic Facility↗
NASA NTRSDate not supplied

Reynolds Number Effects on a 5.2%-Scale High Lift Common Research Model

A 5.2%-scale High Lift Common Research Model (CRM-HL) semispan wind tunnel model was tested at the National Transonic Facility (NTF) wind tunnel in Hampton, VA. One of the primary objectives of the NTF test was to determine the effect of varying Reynolds number on the configuration. The test used a combination of air and cryogenic nitrogen testing to obtain up to flight-like Reynolds numbers. The landing and takeoff configurations of the model were tested at speeds ranging from Mach 0.2 to 0.35. The Reynolds numbers based on the mean aerodynamic chord of the model ranged from 1.6 to 30 million. Overall, the lift increased and drag decreased with increasing Reynolds number for chord Reynolds numbers less than 16 million, following well-established trends. However, some anomalies in the force and moment data were observed in the linear region of the angle of attack range that did not follow expected trends. The force and moment results for both the landing and takeoff configurations are presented, along with surface pressure data for the landing configuration. Incremental effects from the landing gear, nacelle, and horizontal tail on the landing configuration are also presented.

CRM-HL↗
NASA NTRSDate not supplied

Transition Measurements on the SWiFT Model in the National Transonic Facility

Boundary layer transition locations on the Swept Wing Flow Test (SWiFT) Hybrid Wing Body model were measured in the National Transonic Facility (NTF) at the NASA Langley Research Center using several different methods. These methods include sublimating chemical flow visualization for a limited number of low Reynolds number conditions, as well as mean static pressure and dynamic pressure measurements. Results are presented for a range of conditions in the NTF, demonstrating Mach and Reynolds number effects. The transition front locations obtained from the different techniques agree well. A variation of the static pressure transition detection method is described in which continuous angle of attack polars are performed. This approach enables detection of the transition front at more challenging (high Reynolds number) conditions than is possible with sparser data from pitch-pause angle-of-attack polars. The trip dot effectiveness is also verified using all of the available diagnostics. Additionally, low Reynolds number results are compared with those acquired on the same model at the Aircraft Research Association (ARA) facility, and these results show good agreement overall, suggesting similar freestream flow quality conditions of the two facilities.

National Transonic Facility↗
NASA NTRSDate not supplied

Model Preparation Areas for Propulsion Airframe Integration Testing at NASA Langley Research Center

Currently there are three major NASA Langley facilities that perform PAI testing. These include the National Transonic Facility, the 14’x22’ Low Speed Wind tunnel, and the Unitary Plan Wind Tunnel. While each of these facilities have their own model preparation areas, the model preparation area located at the NTF complex that focuses on blowing systems with high mass flow requirements support all of the LaRC facilities. The application of a Propulsion Airframe Integration requires special attention to the air delivery system interaction with the model. These interactions typically focus on the tares across the balance associated with inlet and nozzle performance which are related to the mass flow through the system and the efficiency of the inlet and nozzle geometries. While this paper does not characterize any specific propulsion system, it does focus on the mass flow and pressures requirement needed for pretesting such systems prior to wind tunnel installation. Weight flow boundaries for the air delivery system were identified to range from 0.1 to 20 lbm/sec.

Model Preparation Area↗
NASA NTRSDate not supplied

Numerical Simulation of the High-Speed Leg of the National Transonic Facility

Numerical simulations for the flow inside the high-speed leg of the National Transonic Facility was conducted. The NASA Tetrahedral Unstructured Software System (TetrUSS) with its USM3D_ME solver was used to perform the numerical simulations. USM3D_ME is developed and maintained by NASA Langley Research Center. Simulations were conducted for three configurations: empty tunnel, body of revolution installed, and NASA Common Research Model installed in the test section. Simulations were performed for a test section Mach number of 0.7 and 0.85 and a corresponding Reynolds number of 8 million per ft. A controller was developed that automated dynamic outflow boundary and streamlined the process of running multiple simulations. The use of a dynamic outflow boundary was the key parameter to drive simulation to the desired tunnel conditions. The numerical simulations captured expected flow features in NTF test section and in the tunnel plenum. The simulations depicted that separation of the flow inside the diffuser appears to be asymmetric and more extensive toward the top and bottom walls. Analysis of the flow field were conducted, and the computed drag coefficient compared to wind tunnel data.

NTF↗
DOE OSTI2021

Highly Perfluorinated Covalent Triazine Frameworks Derived from a Low-Temperature Ionothermal Approach Towards Enhanced CO 2 Electroreduction

Perfluorinated covalent triazine frameworks (F-CTFs) have shown unique features and attractive performance in separation and catalysis. However, state-of-art F-CTFs synthesized via the ZnCl 2 -promoted procedure have quite low fluorine contents due to C-F bond cleavage induced by chloride (a Lewis base) and the harsh conditions deployed (400-700 °C). Fabricating F-CTFs with high fluorine contents (> 30 wt%) remains challenging. Herein, we present a low-temperature ionothermal approach (275 °C) to prepare F-CTFs, which is achieved via polymerization of tetrafluoroterephthalonitrile (TFPN) over the Lewis superacids, e.g., zinc triflimide [Zn(NTf 2 ) 2 ] without side reactions. With low catalyst loading (equimolar), F-CTFs are afforded with high fluorine content (31 wt%), surface area up to 367 m 2 g -1 , and micropores around 1.1 nm. The highly hydrophobic F-CTF-1 exhibits good capability to boost electroreduction of CO 2 to CO, with faradaic efficiency of 95.7% at –0.8 V and high current density (–141 mA cm -2 ) surpassing most of the metal-free electrocatalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Binding, Release and Functionalization of Intact Pnictogen Tetrahedra Coordinated to Dicopper Complexes

The bridging MeCN ligand in the dicopper(I) complexes [(DPFN)Cu 2 (μ,η 1 : η 1 -MeCN)][X] 2 (X=weakly coordinating anion, NTf 2 (1 a), FAl[OC 6 F 10 (C 6 F 5 )] 3 (1 b), Al[OC(CF 3 ) 3 ] 4 (1 c)) was replaced by white phosphorus (P 4 ) or yellow arsenic (As 4 ) to yield [(DPFN)Cu 2 (μ,η 2 : η 2 -E 4 )][X] 2 (E=P (2 a-c), As (3 a-c)). The molecular structures in the solid state reveal novel coordination modes for E 4 tetrahedra bonded to coinage metal ions. Experimental data and quantum chemical computations provide information concerning perturbations to the bonding in coordinated E 4 tetrahedra. Reactions with N-heterocyclic carbenes (NHCs) led to replacement of the E 4 tetrahedra with release of P 4 or As 4 and formation of [(DPFN)Cu 2 (μ,η 1 : η 1 - Me NHC)][X] 2 (4 a,b) or to an opening of one E-E bond leading to an unusual E 4 butterfly structural motif in [(DPFN)Cu 2 (μ,η 1 : η 1 -E 4 Dipp NHC)][X] 2 (E=P (5 a,b), E=As (6)). With a cyclic alkyl amino carbene ( Et CAAC), cleavage of two As-As bonds was observed to give two isomers of [(DPFN)Cu 2 (μ,η 2 : η 2 -As 4 Et CAAC)][X] 2 (7 a,b) with an unusual As 4 -triangle+1 unit.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Influence of solvents on electrochemical stability window of ionic liquid solutions

The electrochemical stability window (ESW) defines the voltage range within which an electrolyte remains stable against oxidation and reduction, serving as a key descriptor for ionic liquid (IL)-based systems. The ESWs of 15 ILs with diverse cation-anion combinations were systematically investigated, both in their neat forms and as binary mixtures with three representative solvents, i.e., propylene carbonate (PC), ethylene glycol (EG), and tetrahydrofuran (THF). Cyclic voltammetry on a glassy carbon electrode determined anodic and cathodic stability limits, revealing that ESW protection in IL-solvent mixtures strongly depends on solvent polarity, proticity, and IL compatibility. PC, with a high dielectric constant and aprotic character, broadened anodic limits and moderately stabilized cathodic limits. THF maintained compact interfacial structure, offering additional cathodic protection, whereas EG, being protic, reduced ESWs via proton-coupled electron transfer and hydrogen evolution. The solvent protection trend followed by PC > THF > EG, with bulky, hydrophobic cations ([HMIM] + , [BMPYRR] + ) and weakly coordinating anions ([NTF 2 ] - , [DCA] - , [DEP] - ) showing the highest ESW protection for 50 mol% IL in these solvents. Among the neat ILs, [EMIM][DEP], [HMIM][PF 6 ], and [BMPYRR][DCA] showed wide ESWs of ∼5.5 V. These results provide valuable insight into solvent-modulated electrochemical stability, enabling rational design of IL-based electrolytes for energy storage and electrosynthesis.

25 ENERGY STORAGE↗
DOE OSTI2025

Unraveling the solvation phenomena of Ln 3+ cations in room-temperature ionic liquids: A computational study

Rare-earth elements (REEs), classified as critical materials, are difficult to separate due to their similar chemical properties and slight differences in ionic radius. Room-temperature ionic liquids (RTILs) have gained significant attention for REE separation because of their unique physicochemical properties and environmental advantages. In this study, we have investigated the solvation mechanisms of two RE cations (Ln 3+ ), Nd 3+ (light REE) and Yb 3+ (heavy REE), in two 1-butyl-3-methylimidazolium ([BMIM] + )-based RTILs using bis(trifluoromethylsulfonyl)imide ([NTf 2 ] − ) and acetate ([OAc] − ) as the respective anions, employing classical molecular dynamics (MD) simulations and density functional theory (DFT) techniques. From MD simulations, it is evident that Ln 3+ cations are primarily solvated by RTIL anions in the first solvation shell, while [BMIM] + cations form the second solvation shell with their numbers depending on the size and composition of the first solvation shell. The neutralizing [NO 3 − ] counterions are mainly solvated by [BMIM] + cations in their first solvation shell. Relative free energy change of solvation calculations using thermodynamic integration (TI) method indicate that Yb 3+ is more strongly solvated than Nd 3+ in both RTILs, a trend further supported by DFT calculations. While both methods predict consistent qualitative behavior, differences in models and energy evaluations lead to variations in absolute values. Overall, this study provides a comprehensive understanding of the solvation behavior of Ln 3+ cations in RTILs, demonstrating a stronger solvation preference for the heavy Ln 3+ cation (Yb 3+ ). In conclusion, these findings have implications for the design of RTIL-based separation processes for REEs.

Ash, Tamalika [Ames Lab., and Iowa State Univ., Am↗
DOE OSTI2026

Ionic Liquid-Enhanced Interfaces to Boost Reactive C O2 Capture

The addition of ionic liquids (ILs) to a mixture containing a molecular solvent and other ionic species can induce the heterogeneous redistribution of cations and anions at the gas–liquid interface. This nonuniform redistribution of cations and anions driven by the differences in the solvophilicity of ions can improve the thermophysical and interfacial properties of such mixtures, creating a local chemical environment that is conducive to some reactions. In this work, ILs are added to a mixture of potassium hydroxide (KOH) and ethylene glycol (EG), used as a reactive absorbent and electrolyte in the migration-assisted moisture-gradient (MAMG) process for CO 2 capture. Molecular dynamics (MD) simulations are employed to probe into the effects of complex ion–ion and ion–solvent interactions and to examine the chemical composition at the gas–liquid interface. A total of 12 systems are investigated using molecular simulations to identify trends in the performance of IL additives based on the choice of cation, anion, and IL concentration. The cation effects are studied using IL additives based on 1-ethyl-3-methylimidazolium ([EMIM] + ) and 1-butyl-3-methylimidazolium ([BMIM] + ), while the impact of anions is examined using additives based on dicyanamide [DCA] − , triflate [TfO] − , bistriflimide [NTf 2 ] − , and hexafluorophosphate [PF 6 ] − anions, respectively. The influence of the IL concentration is also evaluated at molar concentrations between 1% and 4%. The simulation results indicate that the use of IL additives can affect the physical CO 2 solubility, surface tension, and the localization of CO 2 around the [OH] − ions at the gas–liquid interface. It is also evident that the choice of cations, anions, and IL concentration determines the extent to which the IL additives impact the local physicochemical properties. Physical dissolution, diffusive transport, and interaction with [OH] − are critical intermediate steps toward reactive CO 2 capture using a liquid absorbent. Hence, the improvement in one or more of these properties, aided by IL additives, is expected to improve the overall CO 2 capture performance. Experiments reaffirmed the impact of IL additives on CO 2 capture performance and the sensitivity to the choice of the cation, anion, and concentration of the IL additive.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Toward Lithium Recovery Using Modular (and Membraneless) Phase Separation and Extraction (MPSE) Technology with Ionic Liquid (IL) Solvents: Effect of Coatings

In this work, a single-channel slope-plate Modular and Membrane-less Phase Separation and Extraction (MPSE) device was fabricated using 3D printing. The slope-plate was designed with an insertable glass slide to enable surface modification with coatings. Self-assembled monolayers (SAMs) and perfluoropolyether (Zdol) coatings were applied to tailor surface wettability and enhance phase separation. Using a model biphasic system of water and hexadecane, both coatings significantly improved the separation efficiency compared to the uncoated device by promoting selective wetting. Building on these results, lithium extraction from a simulated saline solution was investigated using 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf₂]) as the ionic liquid (IL) extractant. The IL effectively extracted Li⁺ from the aqueous phase in bulk extraction, demonstrating its potential for lithium recovery. However, the low interfacial tension between the IL and aqueous phases posed challenges for phase separation. The application of SAM and Zdol coatings effectively mitigated this issue. Overall, integrating tailored surface chemistry with the slope-plate MPSE design shows great promise as an efficient and scalable platform for studying liquid–liquid separation and optimizing ionic liquid–based extraction processes for lithium recovery from saline sources.

3D printing↗
DOE OSTI2021

A Dicopper Nitrenoid by Oxidation of a Cu'Cu' Core: Synthesis, Electronic Structure, and Reactivity

A dicopper nitrenoid complex was prepared by formal oxidative addition of the nitrenoid fragment to a dicopper(I) center by reaction with the iminoiodinane PhINTs (Ts = tosylate). This nitrenoid complex, (DPFN)Cu 2 (μ-NTs)[NTf 2 ] 2 (DPFN = 2,7-bis(fluorodi(2-pyridyl)methyl)-1,8-naphthyridine), is a powerful H atom abstractor that reacts with a range of strong C–H bonds to form a mixed-valence Cu(I)/Cu(II) μ-NHTs amido complex in the first example of a clean H atom transfer to a dicopper nitrenoid core. In line with this reactivity, DFT calculations reveal that the nitrenoid is best described as an iminyl (NR radical anion) complex. The nitrenoid was trapped by the addition of water to form a mixed-donor hydroxo/amido dicopper(II) complex, which was independently obtained by reaction of a Cu 2 (μ-OH) 2 complex with an amine through a protonolysis pathway. Furthermore, this mixed-donor complex is an analogue for the proposed intermediate in copper-catalyzed Chan–Evans–Lam coupling, which proceeds via C–X (X = N or O) bond formation. Treatment of the dicopper(II) mixed donor complex with MgPh 2 (THF) 2 resulted in generation of a mixture that includes both phenol and a previously reported dicopper(I) bridging phenyl complex, illustrating that both reduction of dicopper(II) to dicopper(I) and concomitant C–X bond formation are feasible.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Valence states of cyclotron-produced thallium

The unexpected behavior of thallium atoms, produced in a reaction of gold target with accelerated 3 He ions, in liquid–liquid extraction with [C n mim][NTf 2 ] ionic liquids ( n = 2, 4, 6–8, 10) was investigated. Contrary to the general expectations, a significant proportion of thallium produced in the nuclear reaction was found in a non-monovalent state upon dissolution of the KCl aerosol collector. This finding is critical for the design and evaluation of the forthcoming chemistry experiments with the superheavy element nihonium.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗