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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1961

Large-Scale Wind-Tunnel Tests of Exhaust Ingestion Due to Thrust Reversal on a Four-Engine Jet Transport during Ground Roll

Wind-tunnel tests have been conducted on a large-scale model of a swept-wing jet transport type airplane to study the factors affecting exhaust gas ingestion into the engine inlets when thrust reversal is used during ground roll. The model was equipped with four small jet engines mounted in nacelles beneath the wing. The tests included studies of both cascade and target type reversers. The data obtained included the free-stream velocity at the occurrence of exhaust gas ingestion in the outboard engine and the increment of drag due to thrust reversal for various modifications of thrust reverser configuration. Motion picture films of smoke flow studies were also obtained to supplement the data. The results show that the free-stream velocity at which ingestion occurred in the outboard engines could be reduced considerably, by simple modifications to the reversers, without reducing the effective drag due to reversed thrust.

Tolhurst, William H., Jr.↗
NASA NTRS1996

Tissue-Engineered Skeletal Muscle Organoids for Reversible Gene Therapy

Genetically modified murine skeletal myoblasts were tissue engineered in vitro into organ-like structures (organoids) containing only postmitotic myoribers secreting pharmacological levels of recombinant human growth hormone (rhGH). Subcutaneous organoid implantation under tension led to the rapid and stable appearance of physiological sera levels of rhGH for up to 12 weeks, whereas surgical removal led to its rapid disappearance. Reversible delivery of bioactive compounds from postmitotic cells in tissue engineered organs has several advantages over other forms of muscle gene therapy.

Vandenburgh, Herman↗
NASA NTRS1996

Tissue-Engineered Skeletal Muscle Organoids for Reversible Gene Therapy

Genetically modified murine skeletal myoblasts were tissue engineered in vitro into organ-like structures (organoids) containing only postmitotic myofibers secreting pharmacological levels of recombinant human growth hormone (rhGH). Subcutaneous organoid Implantation under tension led to the rapid and stable appearance of physiological sera levels of rhGH for up to 12 weeks, whereas surgical removal led to its rapid disappearance. Reversible delivery of bioactive compounds from postimtotic cells in tissue engineered organs has several advantages over other forms of muscle gene therapy.

Vandenburgh, Herman↗
NASA NTRS1981

Thrust reversing effects on twin-engine aircraft having nonaxisymmetric nozzles

The effects of thrust reversing on stability, control and vertical tail loads of advanced fighter aircraft are reviewed. Several static test stand and wind tunnel investigations of nonaxisymmetric nozzles with integral thrust reversers are presented, and it is found that base drag on the aft face of reverser panels of blockers provides a significant contribution to in-flight thrust reverser performance. The location of tail surfaces relative to the thrust reverser has significant impact on control surface effectiveness, and depending on thrust reverser location, large vertical tail side force can result from the use of in-flight thrust reversers. It is concluded that highly effective nonaxisymmetric nozzle reversers can be designed to achieve a 50% static reverse thrust.

Capone, F. J.↗
NASA NTRS1985

Static internal performance of a single-engine onaxisymmetric-nozzle vaned-thrust-reverser design with thrust modulation capabilities

An investigation has been conducted at wind-off conditions in the stati-test facility of the Langley 16-Foot Transonic Tunnel. The tests were conducted on a single-engine reverser configuration with partial and full reverse-thrust modulation capabilities. The reverser design had four ports with equal areas. These ports were angled outboard 30 deg from the vertical impart of a splay angle to the reverse exhaust flow. This splaying of reverser flow was intended to prevent impingement of exhaust flow on empennage surfaces and to help avoid inlet reingestion of exhaust gas when the reverser is integrated into an actual airplane configuration. External vane boxes were located directly over each of the four ports to provide variation of reverser efflux angle from 140 deg to 26 deg (measured forward from the horizontal reference axis). The reverser model was tested with both a butterfly-type inner door and an internal slider door to provide area control for each individual port. In addition, main nozzle throat area and vector angle were varied to examine various methods of modulating thrust levels. Other model variables included vane box configuration (four or six vanes per box), orientation of external vane boxes with respect to internal port walls (splay angle shims), and vane box sideplates. Nozzle pressure ratio was varied from 2.0 approximately 7.0.

Leavitt, L. D.↗
NASA NTRS1980

Reverse thrust performance of the QCSEE variable pitch turbofan engine

Results of steady state reverse and forward to reverse thrust transient performance tests are presented. The original quiet, clean, short haul, experimental engine four segment variable fan nozzle was retested in reverse and compared with a continuous, 30 deg half angle conical exlet. Data indicated that the significantly more stable, higher pressure recovery flow with the fixed 30 deg exlet resulted in lower engine vibrations, lower fan blade stress, and approximately a 20 percent improvement in reverse thrust. Objective reverse thrust of 35 percent of takeoff thrust was reached. Thrust response of less than 1.5 sec was achieved for the approach and the takeoff to reverse thrust transients.

Samanich, N. E.↗
NASA NTRS1977

Thrust-augmented vortex attenuation

An experimental investigation was conducted to determine the vortex attenuating effect of engine thrust. Tests were made using a 0.03-scale model of the Boeing 747 transport aircraft as a vortex generating model. A Learjet-class probe model was used to measure the vortex induced rolling moment at a scale separation distance of 1.63 km. These tests were conducted at a lift coefficient of 1.4 at a model velocity of 30.48 m/s. The data presented indicate that engine thrust is effective as a vortex attenuating device when the engines are operated at high thrust levels and are positioned to direct the high energy engine wake into the core of the vortex. The greatest thrust vortex attenuation was obtained by operating the inboard engine thrust reversers at one-quarter thrust and the outboard engines at maximum forward thrust.

Patterson, J. C., Jr.↗
NASA NTRS1977

Reverse pitch fan with divided splitter

A guide vane arrangement is described for improving gas turbine performance in the reverse thrust mode. This flow straightening method produces low losses in the fluid entering a core engine during reverse thrust operations and allows large supercharging of the core engine during forward thrust.

Smith, L. H., Jr.↗
NASA NTRS1997

Thrust reverser with variable nozzle

A thrust reverser is provided for both modulating and reversing bypass flow discharged from a fan through a bypass duct of a turbofan gas turbine engine. The reverser includes an aft cowl joined to a forward cowl and having an aft end surrounding a core engine to define a discharge fan nozzle of minimum flow throat area. The aft cowl is axially translatable relative to the forward cowl from a first position fully retracted against the forward cowl, to a second position partially extended from the forward cowl, and to a third position fully extended from the forward cowl. A plurality of cascade turning vanes are disposed between the forward and aft cowls, and a plurality of thrust reversing deflector doors are pivotally mounted to the aft cowl and bound the bypass duct. The deflector doors are selectively deployed from a stowed position corresponding with the first and second positions of the aft cowl for allowing unrestricted flow of the bypass flow through the fan nozzle. The doors also have a deployed position corresponding with the third position of the aft cowl for substantially deflecting the bypass flow from discharging through the fan nozzle to discharging through the cascade vanes for effecting thrust reverse. Axial translation of the aft cowl between the first and second positions varies flow area of the fan nozzle to vary thrust effected by the discharged bypass flow.

Butler, Lawrence↗
NASA NTRS1980

The development of an elastic reverse gradient garment to be used as a countermeasure for cardiovascular deconditioning

Using a new nomex lycra elastic fabric and individualized garment engineering techniques, reverse gradient garments (RGG's) were designed, constructed, and tested for effectiveness as a countermeasure against cardiovascular deconditioning. By combining torso compensated positive pressure breathing with a distally diminishing gradient of counterpressure supplied by the elastic fabric on the limbs, the RGG acts to pool blood in the extremities of recumbent persons much as though they were standing erect in 1 g. The RGG stresses the vasculature in a fashion similar to that experienced by the normally active man, hence preventing or limiting the development of post weightlessness orthostatic intolerance and related conditions. Four male, college age subjects received daily treatments with the RGG during a 15 day bedrest study. Four additional subjects also underwent the bedrest, but received no treatments; they served as controls. The preliminary indication was that the RGG was somewhat effective in limiting the deconditioning process.

Annis, J. F.↗
DOE OSTI2024

Ultrasound Interim cyber-physical research evaluation

Recent events have presented Medical Practitioners with concerns about safety and privacy implications associated with GE’s VScan MIot Ultrasound Device. Concerns relate to the devices potential risk to broadcast location data that can pose serious risks to device users and patients. This report was commission in collaboration with Augusta University to determine if device concerns pose real threat to operators and patients. In effort to ensure all potential threat vectors are targeted, the initial step was to analyze the supply chain. Here the devices are CT scanned to look for any hardware anomalies that could present threat vectors to users of these devices. (See SRNL-STI-2024-00225 for detailed analysis). No anomalies were found associated with the hardware utilized within the GE VScan Air.

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