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Black, G.

Publications and source records attributed to Black, G..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Computing Rotational/Vibrational Dynamics Of Turbine Engines

Turbine Engine Transient Response Analysis program, TETRA 2, developed to calculate dynamic response of structure of turbine engine to applied stimuli. Includes options for calculation of both transient response and steady-state forced response. Helps turbine engineer in understanding basic transient and steady-state responses of whole structure and in identifying crucial problem areas. Could lead to design of turbine engines responding more robustly to applied stimuli. Written in FORTRAN 77.

Gallardo, V. G.↗
NASA NTRS1988

A new laboratory source of ozone and its potential atmospheric implications

Although 248-nm radiation falls 0.12 eV short of the energy needed to dissociate O2, large densities of ozone (O3) can be produced from unfocused 248-nm KrF excimer laser irradiation of pure O2. As soon as any O3 is present, it strongly absorbs the 248-nanometer radiation and dissociates to vibrationally excited ground state O2 (among other products), with a quantum yield of 0.1 to 0.15. During the laser pulse, a portion of these molecules absorb a photon and dissociate, which results in the production of three oxygen atoms for one O3 molecule destroyed. Recombination then converts these atoms to O3, and thus O3 production in the system is autocatalytic. A deficiency exists in current models of O3 photochemistry in the upper stratosphere and mesosphere, in that more O3 is found than can be explained. A detailed analysis of the system as it applies to the upper atmosphere is not yet possible, but with reasonable assumptions about O2 vibrational distributions resulting from O3 photodissociation and about relaxation rates of vibrationally excited O2, a case can be made for the importance of including this mechanism in the models.

Slanger, T. G.↗
NASA NTRS1985

Turbine-Engine Transient-Rotor Analysis

Computer program developed to predict structural dynamics of rotor system in gas turbine engines subjected to sudden unbalance. TETRA computer code calculates transient structural response of turbine engines due to blade loss or other time-dependent events. Used on structures other than turbine engines with little or no modification.

Galardo, V., Jr.↗
NASA NTRS1983

Blade loss transient dynamics analysis with flexible bladed disk

The transient dynamic response of a flexible bladed disk on a flexible rotor in a two rotor system is formulated by modal synthesis and a Lagrangian approach. Only the nonequilibrated one diameter flexible mode is considered for the flexible bladed disk, while the two flexible rotors are represented by their normal modes. The flexible bladed disk motion is modeled as a combination of two one diameter standing waves, and is coupled inertially and gyroscopically to the flexible rotors. Application to a two rotor model shows that a flexible bladed disk on one rotor can be driven into resonance by an unbalance in the other rotor, and at a frequency equal to the difference in the rotor speeds.

Gallardo, V. C.↗
NASA NTRS1982

Blade loss transient dynamic analysis of turbomachinery

This paper reports on work completed to develop an analytical method for predicting the transient non-linear response of a complete aircraft engine system due to the loss of a fan blade, and to validate the analysis by comparing the results against actual blade loss test data. The solution, which is based on the component element method, accounts for rotor-to-casing rubs, high damping and rapid deceleration rates associated with the blade loss event. A comparison of test results and predicted response show good agreement except for an initial overshoot spike not observed in test. The method is effective for analysis of large systems.

Stallone, M. J.↗
NASA NTRS1980

O/1S/ yield from O3 photodissociation at 1700-2400 A

The paper discusses the O(1S) yield from O3 photodissociation measured in the 1700-2400 A region using synchrotron radiation as a light source. An upper limit for the yield set at 0.1% for the entire photon energy range indicates that the contribution of O(1S) to atmospheric OH production is not significant. The spin restriction for going into the O(1S) + O2/X3Sigma(-)(g)/ channel appears to be the determining factor in the low yield. There are three spin-allowed channels to produce excited O2 molecules with thresholds between 2300 and 2650 A; it is recommended to investigate these dissociative pathways.

Lee, L. C.↗
NASA NTRS1978

CO2 photolysis revisited

Measurements have been made of the absolute oxygen atom yields from CO2 photolysis at 1470 and 1302-1306 A; in both cases the yield is unity. The CO generation rates have also been measured in these two wavelength regions, and they are proportional to the oxygen atom generation rates; by implication the CO quantum yields are thus also unity. The CO deficiencies observed in earlier work on this subject are probably caused by heterogenous processes.

Slanger, T. G.↗
NASA NTRS1978

O/S-1/ interactions - The product channels

The first measurements are reported of the reaction pathways for the interaction between oxygen atoms in the 4.19 eV S-1 state, and four molecules, N2O, CO2, H2O, and NO. Distinction is made between three possible paths - quenching to O(D-1), quenching to O(P-3), and chemical reaction. With N2O, the most reasonable interpretation of the data indicates that there no reaction, in sharp contrast with the interaction between O(D-1) and N2O, which proceeds entirely by reaction. Similarly, there is no reaction with CO2. With H2O, the reactive pathway is the dominant one, although electronic quenching is not negligible. With NO, O(D-1) is the preferred product.

Slanger, T. G.↗
NASA NTRS1975

Technology assessment: What should it be?

The necessity of uncovering unsuspected relationships in proposed actions is discussed along with the feasibility of using decision theoretical models to cope with problems of uncertainty in the future-oriented analyses characteristic of assessments. It is shown that it is necessary to integrate the results of technology assessment with other program analyses and that results of technology assessment be supplied in a form that permits integration with other information.

Black, G.↗
NASA NTRS1974

Photodissociation quantum yields of CO2 between 1200 and 1500 A

Measurements of the photodissociation quantum yields of CO2 have been carried out using various atomic line sources between 1200 and 1500 A. The production of CO was monitored by resonance fluorescence, and the results indicate that where the CO2 absorption spectrum is continuous, the CO quantum yield is high, but where there is structure, the yield is low.

Slanger, T. G.↗
NASA NTRS1974

Output orientation in R and D: A better approach?

Research and development management is examined as it might be performed under an output-oriented approach in which the company's needs for innovations in various product and production areas were identified. It is shown that a company's R and D program is the aggregate of its needs in various areas of its business. The planning, programming and budgeting approach is applied to R and D. The state of theory on R and D decision making in economics is summarized. Abstracts of articles concerning R and D in industry are included.

Black, G.↗
NASA NTRS1974

Electronic-to-vibrational energy transfer efficiency in the O/1 D/-N2 and O/1 D/-CO systems

With the aid of a molecular resonance fluorescence technique, which utilizes optical pumping from the v = 1 level of the ground state of CO by A 1 Pi-X 1 Sigma radiation, a study is made of the efficiency of E-V transfer from O(1 D) to CO. O(1 D) is generated at a known rate by O2 photodissociation at 1470 A in an intermittent mode, and the small modulation of the fluorescent signal associated with CO (v = 1) above the normal thermal background is interpreted in terms of E-V transfer efficiency. The CO (v = 1) lifetime in this system is determined mainly by resonance trapping of the IR fundamental band, and is found to be up to ten times longer than the natural radiative lifetime. For CO, (40 plus or minus 8)% of the O(1 D) energy is converted into vibrational energy. By observing the effect of N2 on the CO (v = 1) fluorescent intensity and lifetime, it is possible to obtain the E-V transfer efficiency for the system O(1 D)-N2 relative to that for O(1 D)-CO. The results indicate that the efficiency for N2 is (83 plus or minus 10)% of that for CO.

Slanger, T. G.↗
NASA NTRS1972

Kinetics of O/super 3P/ + CO + M recombination.

Measurement of rate coefficients over the temperature range from 250 to 370 K for the three-body recombination of O(super 3P) with CO. Earlier results at 300 K have been re-evaluated and were found to have been influenced by unknown impurities in the CO, which have now been removed by more elaborate purification methods. For CO as the third body, the rate constant is given by K = 6.5 x 10 to the minus 33rd exp (-4340 plus or minus 550/RT) cm to the 6th power per sq molecule per sec. For N2 and CO2, the 296 K rate constants are 2.3 and 6.2 x 10 to the minus 36th cm to the 6th power per sq molecule per sec, respectively.

Slanger, T. G.↗
NASA NTRS1971

Technology assessment: What should it be?

A report on technology assessment (TA) is presented. Topics discussed include: the nature of TA, TA used as an analytical method for natural and social sciences, and the uncertain consequences of TA.

Black, G.↗