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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Hot gas ingestion: From model results to full scale engine testing

An overview is presented of a joint NASA Lewis McDonnell Aircraft Co. Hot Gas Ingestion (HGI) test program in NASA Lewis' 9 x 15 foot Low Speed Wind Tunnel (LSWT). Advanced short takeoff vertical landing (ASTOVL) aircraft capable of operating from remote sites, damaged runways, aircraft carriers and small air-capable ships are being pursued for deployment around the turn of the century. To achieve this goal, it is important that technologies critical to this unique class of aircraft be developed. One of the ASTOVL concepts, the vectored thrust, has as its critical technology item, the potential of hot gas ingestion (which occurs during vertical flight operation while in ground effect) as a key development issue. Recognizing this need, NASA Lewis Powered Lift Section and McAir have defined a cooperative program for testing in the Lewis 9 x 15 foot LSWT. This program is described in detail.

Johns, Albert L.↗
NASA NTRS1986

F-106 data summary and model results relative to threat criteria and protection design analysis

The NASA F-106 has acquired considerable data on the rates-of-change of EM parameters on the aircraft surface during 690 direct lightning strikes while penetrating thunderstorms at altitudes from 15,000 to 40,000 feet. The data are presently being used in updating previous lightning criteria and standards. The new lightning standards will, therefore, be the first which reflect actual aircraft responses measured at flight altitudes.

Pitts, F. L.↗
NASA NTRS1993

The radiative budgets of a tropical mesoscale convective system during the EMEX-STEP-AMEX experiment. I - Observations. II - Model results

The spatial radiation heating budget associated with tropical mesoscale convective systems (MCSs) is studied and the change of this heating/budget throughout the life cycle of such a cloud system is investigated. The movements of an EMEX 9 cloud cluster are described. The vertical structure of the cluster contains two types of imbedded convection: an upright vertical structure and a pronounced rearward slope with vertical extent of 14.5 km or more and a horizontal scale of about 40 km. The cloud base and cloud top altitude in the stratiform region are of the order of 4.8 km and 15-16 km, respectively. The upward and downward solar flux profiles suggest very little solar heating in these regions. A tropical MCS that occurred during the EMEX Mission 9 is simulated, and the simulation is shown to broadly agree with the observations. The simulation results, which are reported in detail, show how tropical mesoscale cloud systems provide an effective radiative heat source for the tropical atmosphere.

Wong, Takmeng↗
NASA NTRS2004

MODIS Solar Diffuser Attenuation Screen Modeling Results

On-orbit calibration of the reflected solar bands on the EOS Moderate Resolution Imaging Spectroradiometer (MODIS) is accomplished by have the instrument view a high reflectance diffuse surface illuminated by the sun. For some of the spectral bands this proves to be much too bright a signal that results in the saturation of detectors designed for measuring low reflectance (ocean) surfaces signals. A mechanical attenuation device in the form of a pin hole screen is used to reduce the signals to calibrate these bands. The sensor response to solar illumination of the SD with and without the attenuation screen in place will be presented. The MODIS detector response to the solar diffuser is smooth when the attenuation screen is absent, but has structures up to a few percent when the attenuation screen is present. This structure corresponds to non-uniform illumination from the solar diffuser. Each pin hole produces a pin-hole image of the sun on the solar diffuser, and there are very many pin hole images of the sun on the solar diffuser for each MODIS detector. Even though there are very many pin-hole images of the sun on the solar diffuser, it is no longer perfectly uniformly illuminated. This non-uniformly illuminated solar diffuser produces intensity variation on the focal planes. The results of a very detailed simulation will be discussed which show how the illumination of the focal plane changes as a result of the attenuation, and the impacts on the calibration will be discussed.

Waluschka, Eugene↗
NASA NTRS2004

Use of Strain Measurements from Acoustic Bench Tests of the Battleship Flowliner Test Articles To Link Analytical Model Results to In-Service Resonant Response

The paper will discuss practical and analytical findings of a test program conducted to assist engineers in determining which analytical strain fields are most appropriate to describe the crack initiating and crack propagating stresses in thin walled cylindrical hardware that serves as part of the Space Shuttle Main Engine's fuel system. In service the hardware is excited by fluctuating dynamic pressures in a cryogenic fuel that arise from turbulent flow/pump cavitation. A bench test using a simplified system was conducted using acoustic energy in air to excite the test articles. Strain measurements were used to reveal response characteristics of two Flowliner test articles that are assembled as a pair when installed in the engine feed system.

Frady, Greg↗
NASA NTRS2010

GPM Microwave Imager Engineering Model Results

The Global Precipitation Measurement (GPM) Microwave Imager (GMI) Instrument is being developed by Ball Aerospace and Technology Corporation (BATC) for the GPM program at NASA Goddard. The Global Precipitation Measurement (GPM) mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and more frequent precipitation measurements. The GPM Microwave Imager (GMI) will be used to make calibrated, radiometric measurements from space at multiple microwave frequencies and polarizations. GMI will be placed on the GPM Core Spacecraft together with the Dualfrequency Precipitation Radar (DPR). The DPR is two-frequency precipitation measurement radar, which will operate in the Ku-band and Ka-band of the microwave spectrum. The Core Spacecraft will make radiometric and radar measurements of clouds and precipitation and will be the central element ofGPM's space segment. The data products from GPM will provide information concerning global precipitation on a frequent, near-global basis to meteorologists and scientists making weather forecasts and performing research on the global energy and water cycle, precipitation, hydrology, and related disciplines. In addition, radiometric measurements from GMI and radar measurements from the DPR will be used together to develop a retrieval transfer standard for the purpose of calibrating precipitation retrieval algorithms. This calibration standard will establish a reference against which other retrieval algorithms using only microwave radiometers (and without the benefit of the DPR) on other satellites in the GPM constellation will be compared.

Newell, David↗
NASA NTRSDate not supplied

Comparison of Equivalent System Mass (ESM) and Modeling Results from Improved Heat Loss Approaches for the Carbon Dioxide Deposition (CDep) System

Proper insulation on any type of cryogenic system is essential for its performance to be optimal, as a poorly insulated system will allow for significant heat loss. Different insulation arrangements for CDep were considered, and performance was simulated and measured in Modelica. Heat loss was correlated to cycle time and CO2 deposition efficiency, which led to overall system power usage. Mass, volume, and power consumption were weighted accordingly in the ESM calculations to guide selection of the CDep insulation scheme.

Marian Alcid↗
NASA NTRS1987

Results of acoustic tests of a Prop-Fan model

Results of acoustic tests in a low speed open jet anechoic wind tunnel are presented for a counter rotation Prop-Fan model. The model tested had 5 front and 5 rear rotor blades with swept planform. Noise spectra are presented showing the influence of operating and configuration variables such as: (1) power absorption, (2) tip speed, (3) rotor-rotor spacing, (4) power split between the front and rear blade rows, (5) variation of the RPM ratio between front and rear blade rows, (6) tractor versus pusher (pylon effects), and (7) angle of attack. In addition to model scale results, calculated levels derived from test are presented showing the influence of the above variables on Effective Perceived Noise Level of a 13.1 ft diameter Prop-Fan at a flyover distance of 1500 ft. It was found that the strongest effects are caused by tip speed and power absorption. A significant finding was that there is an optimum operating tip speed for minimum noise for a given power absorption. Effects of other parametric variations are generally small but measurable. In order to minimize noise to meet airplane certification limits, operation at moderate tip speeds and power absorption is shown to be desirable. Accuracy of predicted Effective Perceived Noise Level is shown to be good with the best accuracy in the 590 to 670 ft/sec tip speed range.

Metzger, F.B.↗