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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 NTRS1972

Simulator evaluation of the flying qualities of externally blown flap and augmentor wing transport configurations

Concurrent simulations of powered-lift STOL transport aircraft having either an externally blown flap configuration or an augmentor wing configuration were conducted. The following types of simulators of varying sophistication were used: (1) a simple fixed-base simulation with a simple visual display, (2) a more complex fixed-base simulation using a realistic transport cockpit and a high-quality visual display, and (3) a six-degree-of-freedom motion simulator that had a realistic transport cockpit and a sophisticated visual display. The unaugmented flying qualities determined from these simulations were rated as unacceptable for both the externally blown flap and augmentor wing configurations. The longitudinal, lateral-directional, and single-engine-failure characteristics were rated satisfactory with extensive augmentation, including pitch and roll command systems, flight-path (or speed) augmentation, turn coordination, and effective yaw damping. However, the flare and landing characteristics from any approach glide-path angle in excess of 4 deg were rated as unsatisfactory but acceptable.

Kier, D. A.↗
NASA NTRS2012

Flight Dynamics Modeling and Simulation of a Damaged Transport Aircraft

A study was undertaken at NASA Langley Research Center to establish, demonstrate, and apply methodology for modeling and implementing the aerodynamic effects of MANPADS damage to a transport aircraft into real-time flight simulation, and to demonstrate a preliminary capability of using such a simulation to conduct an assessment of aircraft survivability. Key findings from this study include: superpositioning of incremental aerodynamic characteristics to the baseline simulation aerodynamic model proved to be a simple and effective way of modeling damage effects; the primary effect of wing damage rolling moment asymmetry may limit minimum airspeed for adequate controllability, but this can be mitigated by the use of sideslip; combined effects of aerodynamics, control degradation, and thrust loss can result in significantly degraded controllability for a safe landing; and high landing speeds may be required to maintain adequate control if large excursions from the nominal approach path are allowed, but high-gain pilot control during landing can mitigate this risk.

Shah, Gautam H.↗
NASA NTRS1990

The structure of turbulent channel flow with passive scalar transport

The simulation of turbulent channel flow, with various passive markers, was examined to investigate the local mechanisms of passive scalar transport. We found significant differences between the local transport of heat and momentum, even when the molecular and turbulent Prandtl numbers are of order one. These discrepancies can be attributed to the role of the pressure. We also found that the heat is a poor marker of the vorticity field outside of the near wall region and that scalar transport over significant distances results from the aggregate effect of many turbulent eddies.

Guezennec, Y.↗
NASA NTRS2005

Simulations of Dynamics and Transport during the September 2002 Antarctic Major Warming

A mechanistic model simulation initialized on 14 September 2002, forced by 100-hPa geopotential heights from Met Office analyses, reproduced the dynamical features of the 2002 Antarctic major warming. The vortex split on approx.25 September; recovery after the warming, westward and equatorward tilting vortices, and strong baroclinic zones in temperature associated with a dipole pattern of upward and downward vertical velocities were all captured in the simulation. Model results and analyses show a pattern of strong upward wave propagation throughout the warming, with zonal wind deceleration throughout the stratosphere at high latitudes before the vortex split, continuing in the middle and upper stratosphere and spreading to lower latitudes after the split. Three-dimensional Eliassen-Palm fluxes show the largest upward and poleward wave propagation in the 0(deg)-90(deg)E sector prior to the vortex split (coincident with the location of strongest cyclogenesis at the model's lower boundary), with an additional region of strong upward propagation developing near 180(deg)-270(deg)E. These characteristics are similar to those of Arctic wave-2 major warmings, except that during this warming, the vortex did not split below approx.600 K. The effects of poleward transport and mixing dominate modeled trace gas evolution through most of the mid- to high-latitude stratosphere, with a core region in the lower-stratospheric vortex where enhanced descent dominates and the vortex remains isolated. Strongly tilted vortices led to low-latitude air overlying vortex air, resulting in highly unusual trace gas profiles. Simulations driven with several meteorological datasets reproduced the major warming, but in others, stronger latitudinal gradients at high latitudes at the model boundary resulted in simulations without a complete vortex split in the midstratosphere. Numerous tests indicate very high sensitivity to the boundary fields, especially the wave-2 amplitude. Major warmings occurred for initial fields with stronger winds and larger vortices, but not smaller vortices, consistent with the initiation of wind-deceleration by upward-propagating waves near the poleward edge of the region where wave 2 can propagate above the jet core. Thus, given the observed 100-hPa boundary forcing, stratospheric preconditioning is not needed to reproduce a major warming similar to that observed. The anomalously strong forcing in the lower stratosphere can be viewed as the primary direct cause of the major warming.

winds↗
NASA NTRS1971

Digital autopilots: Design considerations and simulator evaluations

The development of a digital autopilot program for a transport aircraft and the evaluation of that system's performance on a transport aircraft simulator is discussed. The digital autopilot includes three axis attitude stabilization, automatic throttle control and flight path guidance functions with emphasis on the mode progression from descent into the terminal area through automatic landing. The study effort involved a sequence of tasks starting with the definition of detailed system block diagrams of control laws followed by a flow charting and programming phase and concluding with performance verification using the transport aircraft simulation. The autopilot control laws were programmed in FORTRAN 4 in order to isolate the design process from requirements peculiar to an individual computer.

Osder, S.↗
NASA NTRS2005

Design, Development, and Innovation of an Interactive Multimedia Training Simulator for Responding to Air Transportation Bomb Threats

This paper describes an interactive multimedia simulator for air transportation bomb threat training. The objective of this project is to improve the air transportation sector s capability to respond to bomb threats received by commercial airports and aircraft. The simulator provides realistic training on receiving and responding to a variety of bomb threats that might not otherwise be possible due to time, cost, or operational constraints. Validation analysis indicates that the use of the simulator resulted in statistically significant increases in individual ability to respond to these types of bomb threats.

Chung, Christopher A.↗
NASA NTRS1983

Application of nonlinear adaptive motion washout to transport ground-handling simulation

The application of a nonlinear coordinated adaptive motion washout to the transport ground-handling environment is documented. Additions to both the aircraft math model and the motion washout system are discussed. The additions to the simulated-aircraft math model provided improved modeling fidelity for braking and reverse-thrust application, and the additions to the motion-base washout system allowed transition from the desired flight parameters to the less restrictive ground parameters of the washout.

Parrish, R. V.↗
NASA NTRS1970

The Simulation of a Jumbo Jet Transport Aircraft. Volume 2: Modeling Data

The manned simulation of a large transport aircraft is described. Aircraft and systems data necessary to implement the mathematical model described in Volume I and a discussion of how these data are used in model are presented. The results of the real-time computations in the NASA Ames Research Center Flight Simulator for Advanced Aircraft are shown and compared to flight test data and to the results obtained in a training simulator known to be satisfactory.

Hanke, C. R.↗
NASA NTRS1998

Making Intercontinental Burning Influences Quantitative: Lessons on Transport and Geochemistry From the 3-D Simulation of CO in PEM-T A and TRACE-A

We report on two aspects of the simulation of global transport of plumes originating from subtropical biomass fires. We use of meteorological assimilation (MM5) at 2-degree resolution with a Grail cloud parameterization and a Blackadar-based planetary boundary layer parameterization. Ames's GRACES model provides emissions, transport, and an appropriate level of simulated chemical transformation. We have worked with passive-tracer CO or linear chemistry. This is appropriate since we find major work to be done in evaluating CO source strengths and transport mechanisms before chemical integrations could be meaningful. First, we present mechanisms by which CO and other pollutants are introduced into the free troposphere, and are then transported with hate dilution from approx. 0 to approx. 180 degrees longitude. One principal conduit for these plumes is the vernal subtropical jet; however the plumes appear at various altitudes and latitudes as they influenced by frontal motions and (most likely) radiative processes. A common, repeated pattern of transport has pollutant plumes arriving in the distant Pacific Ocean from Africa and South America at 25 degrees south and 14 km altitude. Following this, there is then a general appearance of pollution at extending down to 5 kin at more equatorial (10 S) and polar latitudes (to 45 S). Second, we evaluate the quantitative success of our simulation. (Such success requires efforts considerably beyond trajectory analyses, and is necessary for our community to claim an understanding of the effects of biomass burning on global atmospheric chemistry and the planet's trend in oxidizing capacity.) We find that we simulate most pollution episodes sampled by Glenn Sachse's CO instrument and the Blake hydrocarbon analyses during PENT A. We will present our current ideas on why our general levels appear satisfactory when the observations are within 20 ppb of background levels, but substantially miss the variability associated with the most intense biomass burning plumes. As time allows, we will speculate on the origins of a class of plumes that appear in the mid-troposphere, but are missing from our simulations.

Chatfield, Robert↗
NASA NTRS1987

Simulation of charged particle transport on the MPP

Computations of cosmic ray transport based upon finite difference methods are afflicted by instabilities, inaccuracies, and artifacts. To avoid these problems, a Monte Carlo formulation was developed which is closely related not only to the finite difference formulation, but also to the underlying physics of transport phenomena. Implementations of this approach are currently running on the Massively Parallel Processor at Goddard, whose enormous computing power overwhelms the poor statistical accuracy that usually limits the use of stochastic methods. In a Monte Carlo simulation of rectilinear transport, the coherent and diffusive effects that appeared are in good quantitative agreement with both finite difference and analytical calculations.

Earl, James A.↗
NASA NTRS2006

A Test of Sensitivity to Convective Transport in a Global Atmospheric CO2 Simulation

Two approximations to convective transport have been implemented in an offline chemistry transport model (CTM) to explore the impact on calculated atmospheric CO2 distributions. GlobalCO2 in the year 2000 is simulated using theCTM driven by assimilated meteorological fields from the NASA s Goddard Earth Observation System Data Assimilation System, Version 4 (GEOS-4). The model simulates atmospheric CO2 by adopting the same CO2 emission inventory and dynamical modules as described in Kawa et al. (convective transport scheme denoted as Conv1). Conv1 approximates the convective transport by using the bulk convective mass fluxes to redistribute trace gases. The alternate approximation, Conv2, partitions fluxes into updraft and downdraft, as well as into entrainment and detrainment, and has potential to yield a more realistic simulation of vertical redistribution through deep convection. Replacing Conv1 by Conv2 results in an overestimate of CO2 over biospheric sink regions. The largest discrepancies result in a CO2 difference of about 7.8 ppm in the July NH boreal forest, which is about 30% of the CO2 seasonality for that area. These differences are compared to those produced by emission scenario variations constrained by the framework of Intergovernmental Panel on Climate Change (IPCC) to account for possible land use change and residual terrestrial CO2 sink. It is shown that the overestimated CO2 driven by Conv2 can be offset by introducing these supplemental emissions.

Bian, H.↗