SEARCH · Engineering Papers

Results for “predictive analytics”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22

All sources NASA NTRS DOE OSTI

NASA NTRS1973

Cyclic arc plasma tests of RSI materials using a preheater

The results of a test program are reported in which a preheater was used with an arc plasma stream to study the thermal response of samples of candidate reusable surface insulation materials for the space shuttle. The preheater simulated the shuttle temperature history during the first and last portions of the test cycle, which could not be simulated by the air arc plasma flow. Pre- and post-test data taken for each of the materials included magnified views, optical properties, and chemical analyses. The test results indicate that the mullite base samples experience higher surface temperatures than the other materials at heating rates greater than 225 kw/sq m. The ceramic fibrous mullite and silica coatings show noncatalytic wall behavior. Internal temperature response data for the materials are compared and correlated with analytical predictions.

Stewart, D. A.↗

NASA NTRS1972

Evaluation of acoustic cavities for combustion stabilization.

The stabilizing influence of acoustic cavities (quarterwave acoustic resonators) on acoustic modes of combustion instability has been studied. The ability to analytically predict cavity damping was improved. Relatively good agreement between predicted damping and measured stability was demonstrated. Full-scale motor firings were made to evaluate the influence of several parameters on stability. Results from these firings showed that stability was changed, but not dramatically, by changes in the engine operating conditions. Variations in the film-coolant flowrate do not significantly affect cavity stabilization. The ability to stabilize an engine with unconventional cavity configurations was demonstrated.

Oberg, C. L.↗

NASA NTRS1972

Multiple soliton production and the Korteweg-de Vries equation.

Compressive square-wave pulses are launched in a double-plasma device. Their evolution is interpreted according to the Korteweg-de Vries description of Washimi and Taniuti. Square-wave pulses are an excitation for which an explicit solution of the Schrodinger equation permits an analytical prediction of the number and amplitude of emergent solitons. Bursts of energetic particles (pseudowaves) appear above excitation voltages greater than an electron thermal energy, and may be mistaken for solitons.

Hershkowitz, N.↗

NASA NTRS1972

Silicon-germanium technology program of the Jet Propulsion Laboratory.

The outer planetary exploration missions studied by the Jet Propulsion Laboratory require silicon-germanium radioisotope thermoelectric generators (RTGs) in which the factors of safety are as low as is compatible with the reliable satisfaction of the power needs. Work on silicon germanium sublimation performed at the Jet Propulsion Laboratory is presented. Analytical modeling work on the solid-diffusion process involved in the steady-state (free) sublimation of silicon germanium is described. Analytical predictions are made of the sublimation suppression which can be achieved by using a cover gas. A series of accelerated (high-temperature) tests which were performed on simulated hardware (using four SiGe couples) to study long-term sublimation and reaction mechanisms are also discussed.

De Winter, F.↗

NASA NTRS1973

Rotor noise due to inflow turbulence.

The interaction of turbulent velocity fluctuations of the inflow with rotor blades and the resulting acoustic radiation is examined in terms of: dipole sources due to blade loading, monopole sources due to thickness of the rotating blades, and quadrupole sources due to velocity fluctuations in the flow region. Depending upon the length and time scales of the turbulence, sufficient number of blades may interact with a coherent eddy to radiate noise with discrete peaks at blade passing frequency and its harmonics. Theoretical estimates of acoustic radiation to on-axis points from a typical subsonic rotor are presented, and it is noted that the discrete tone noise is primarily from dipole radiation. Discrete tone noise levels observed in narrow band analysis of test data show reasonable agreement with analytical predictions.

Rao, G. V. R.↗

NASA NTRS1973

Three-dimensional hypersonic transitional/turbulent mean flow profiles.

Detailed three-dimensional compressible transitional/turbulent boundary-layer profiles are presented for use as test cases in numerical and integral calculation procedures. The profiles were obtained from tests conducted in the Mach 20 leg of the Langley High Reynolds Number Helium Facility. The presented data represent an arduous test case for analytical prediction methods, since 'low Reynolds number' and precursor transition effects should probably be accounted for to accurately predict the boundary-layer growth and development.

Fischer, M. C.↗

NASA NTRS1973

Sound measurements within and in the radiated field of an annular duct with flow.

Recent theory on sound propagation for flow ducts initiated a research program (sponsored by NASA-Langley, Contract NAS1-10472) which has the objective of comparing detailed acoustical measurements with the analytical predictions for sound propagation in a duct with sheared flow. The effects considered experimentally mean flow, shear, wall impedance, and source distribution on sound propagation within and radiation from finite lenght annular ducts. Results reported here are confined to acoustic distribution in hard annular ducts with and without mean flow and radiated field patterns for the same conditions. The acoustic distributions are shown for single and multi-mode excitation. The flow duct facility is also described.

Plumblee, H. E.↗

NASA NTRS1974

Film cooling in a combustor operating at fuel-rich exit conditions

Data were taken with a film-cooled test plate placed in the exhaust stream of a rectangular combustor. Results showed that in a fuel-rich zone, fuel entrained into the film-cooling air would burn at the conditions tested. Test conditions were cooling-gas flow rates, 9.5 and 5 percent of total gas flow; cooling-gas velocities, 23 and 12 m/sec; ambient-temperature cooling gas; hot-gas velocity, nominally 215 m/sec; fuel-air ratio to stoichiometric fuel-air ratio values of 0.1, 0.8, 1.0, 1.2, and 1.35, resulting in hot-gas temperatures from 590 to 2100 K; and atmospheric pressure. Analytical prediction of wall temperatures agreed reasonably well with experimental results.

Tacina, R. R.↗

NASA NTRS1974

Diffusive ignition and combustion in a wall jet

Hydrogen is injected from a downstream facing step in a wall into a high-temperature stream. Temperature and hydroxyl radical concentration are measured downstream of the injection plane by means of ultraviolet absorption spectroscopy. The experimental results are compared with theory which is based on a finite-difference solution of boundary-layer equations. Finite-rate kinetics equations are included in the analysis. The analytic predictions are also compared with previously obtained experimental results which are based on probe measurements. Comparison is made between calculated and observed ignition distances.

Kurkov, A. P.↗

NASA NTRS1974

Booster aerodynamic heating: Test support

Several technical areas were encompassed in providing support for booster thermal environment test work. These areas included: (1) cavity flow heating, (2) rarefied flow heating, and (3) impulse operated model research and testing. Cavity flow heating problems were studied with respect to the proposed altitude control motors for the space shuttle. Available literature on this subject was reviewed and analytical predictive methods were summarized for use in planning testing work. Rarefied flow heating data was reviewed and correlated. The study showed the importance of considering rarefied flow conditions in launch thermal environment prediction. Impulse operated model research and testing was conducted to provide a basis for understanding and designing such models for booster thermal environment testing.

Engel, C. D.↗

NASA NTRS1973

Long-term cryogenic space storage system

Discussion of the design, fabrication and testing of a 225-cu ft spherical cryogenic storage system for long-term subcritical applications under zero-g conditions in storing subcritical cryogens for space vehicle propulsion systems. The insulation system design, the analytical methods used, and the correlation between the performance test results and analytical predictions are described. The best available multilayer insulation materials and state-of-the-art thermal protection concepts were applied in the design, providing a boiloff rate of 0.152 lb/hr, or 0.032% per day, and an overall heat flux of 0.066 Btu/sq ft hr based on a 200 sq ft surface area. A six to eighteen month cryogenic storage is provided by this system for space applications.

Hopkins, R. A.↗

NASA NTRS1974

Diffusive ignition and combustion in a wall jet

Kurkov, A. P.↗

NASA NTRS1974

A review of air transport noise

Flight vehicles are characterized according to their manner of operation and type of propulsion system, and their associated sources of noise are identified. Available noise reduction technology as it relates to engine cycle design and to power plant component design is summarized. Such components as exhaust jets, fans, propellers, rotors, airflow-surface interactions, and reciprocating engine exhausts are discussed, along with their noise reduction potentials. Significant aircraft noise reductions are noted to have been accomplished by the application of available technology in support of noise certification rules. Improved analytical prediction methods, and well controlled validation experiments supported by advanced design aeroacoustic facilities, are required as a basis for an effective integrated systems approach to aircraft noise control.

Hubbard, H. H.↗

NASA NTRS1974

Viking Mars lander 1975 dynamic test model/orbiter developmental test model forced vibration test

The Viking Mars Lander 1975 dynamic test model and orbiter developmental test model were subjected to forced vibration sine tests. Flight acceptance (FA) and type approval (TA) test levels were applied to the spacecraft structure in a longitudinal test configuration using a 133,440-N (30,000-lb) force shaker. Testing in the two lateral axes (X, Y) was performed at lower levels using four 667-N (150-lb) force shakers. Forced vibration qualification (TA) test levels were successfully imposed on the spacecraft at frequencies down to 10 Hz. Measured responses showed the same character as analytical predictions, and correlation was reasonably good. Because of control system test tolerances, orbiter primary structure generally did not reach the design load limits attained in earlier static testing. A post-test examination of critical orbiter structure disclosed no apparent damage to the structure as a result of the test environment.

Fortenberry, J.↗

NASA NTRS1973

Feasibility of remote sensing for detecting thermal pollution. Part 1: Feasibility study. Part 2: Implementation plan

A feasibility study for the development of a three-dimensional generalized, predictive, analytical model involving remote sensing, in-situ measurements, and an active system to remotely measure turbidity is presented. An implementation plan for the development of the three-dimensional model and for the application of remote sensing of temperature and turbidity measurements is outlined.

Veziroglu, T. N.↗

NASA NTRS1974

Design, fabrication and test of graphite/epoxy metering truss structure components, phase 3

The design, materials, tooling, manufacturing processes, quality control, test procedures, and results associated with the fabrication and test of graphite/epoxy metering truss structure components exhibiting a near zero coefficient of thermal expansion are described. Analytical methods were utilized, with the aid of a computer program, to define the most efficient laminate configurations in terms of thermal behavior and structural requirements. This was followed by an extensive material characterization and selection program, conducted for several graphite/graphite/hybrid laminate systems to obtain experimental data in support of the analytical predictions. Mechanical property tests as well as the coefficient of thermal expansion tests were run on each laminate under study, the results of which were used as the selection criteria for the single most promising laminate. Further coefficient of thermal expansion measurement was successfully performed on three subcomponent tubes utilizing the selected laminate.

Source record↗

NASA NTRS1975

Thermal acoustic oscillations, volume 2

A number of thermal acoustic oscillation phenomena and their effects on cryogenic systems were studied. The conditions which cause or suppress oscillations, the frequency, amplitude and intensity of oscillations when they exist, and the heat loss they induce are discussed. Methods of numerical analysis utilizing the digital computer were developed for use in cryogenic systems design. In addition, an experimental verification program was conducted to study oscillation wave characteristics and boiloff rate. The data were then reduced and compared with the analytical predictions.

Spradley, L. W.↗

NASA NTRS1975

Trends in aircraft noise control

Flight vehicles are characterized according to their manner of operation and type of propulsion system; and their associated sources of noise are identified. Available noise reduction technology as it relates to engine cycle design and to powerplant component design is summarized. Such components as exhaust jets, fans, propellers, rotors, blown flaps, and reciprocating-engine exhausts are discussed, along with their noise reduction potentials. Significant aircraft noise reductions are noted to have been accomplished by the application of available technology in support of noise certification rules. Further noise reductions to meet more stringent future noise regulations will require substantial additional technology developments. Improved analytical prediction methods, and well-controlled validation experiments supported by advanced-design aeroacoustic facilities, are required as a basis for an effective integrated systems approach to aircraft noise control.

Hubbard, H. H.↗