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  • COMPUTER PROGRAMMING AND SOFTWARE  (4)
  • PROPELLANTS AND FUELS  (4)
  • AIRCRAFT PROPULSION AND POWER  (3)
  • 1985-1989  (11)
  • 1
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    Design principles for an interactive program derivation system (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The main design principles of an interactive program transformation system called FOCUS are outlined. Its important characteristics are its human-oriented deduction techniques based replacement, emphasis on small search spaces, and the use of a tree structure to organize program derivations. The tree structure presents to the user a static picture of the derivation process and promotes flexibility in the development of derivations. The system keeps track of dependencies between different parts of derivations, and records the derivation activity for later use in automatic replay.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
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    NASA TECHNICAL REPORTS
  • 2
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    Analysis of an unswept propfan blade with a semiempirical dynamic stall model (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The time history response of a propfan wind tunnel model with dynamic stall is studied analytically. The response obtained from the analysis is compared with available experimental data. The governing equations of motion are formulated in terms of blade normal modes which are calculated using the COSMIC-NASTRAN computer code. The response analysis considered the blade plunging and pitching motions. The lift, drag and moment coefficients for angles of attack below the static stall angle are obtained from a quasi-steady theory. For angles above static stall angles, a semiempirical dynamic stall model based on a correction to angle of attack is used to obtain lift, drag and moment coefficients. Using these coefficients, the aerodynamic forces are calculated at a selected number of strips, and integrated to obtain the total generalized forces. The combined momentum-blade element theory is used to calculate the induced velocity. The semiempirical stall model predicted a limit cycle oscillation near the setting angle at which large vibratory stresses were observed in an experiment. The predicted mode and frequency of oscillation also agreed with those measured in the experiment near the setting angle.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-4083 , E-4196 , NAS 1.15:4083
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Transformational derivation of programs using the Focus system (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A program derivation support system called Focus is being constructed. It will formally derive programs using the paradigm of program transformation. The following issues are discussed: (1) the integration of validation and program derivation activities in the Focus system; (2) its tree-based user interface; (3) the control of search spaces in program derivation; and (4) the structure and organization of program derivation records. The inference procedures of the system are based on the integration of functional and logic programming principles. This brings about a synthesis of paradigms that were heretofore considered far apart, such as logical and executable specifications and constructive and transformational approaches to program derivation. A great emphasis has been placed, in the design of Focus, on achieving small search spaces during program derivation. The program manipulation operations such as expansion, simplification and rewriting were designed with this objective. The role of operations that are expensive in search spaces, such as folding, has been reduced. Program derivations are documented in Focus in a way that the high level descriptions of derivations are expressed only using program level information. All the meta-level information, together with dependencies between derivations of program components, is automatically recorded by the system at a lower level of description for its own use in replay.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-CR-184875 , NAS 1.26:184875
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  • 4
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    Objects as closures: Abstract semantics of object oriented languages (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: We discuss denotational semantics of object-oriented languages, using the concept of closure widely used in (semi) functional programming to encapsulate side effects. It is shown that this denotational framework is adequate to explain classes, instantiation, and inheritance in the style of Simula as well as SMALLTALK-80. This framework is then compared with that of Kamin, in his recent denotational definition of SMALLTALK-80, and the implications of the differences between the two approaches are discussed.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: NASA-CR-184877 , NAS 1.26:184877
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  • 5
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    Degradation mechanisms of sulfur and nitrogen containing compounds during thermal stability testing of model fuels (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The degradation behavior of n-dodecane (singly or in combination with S- and N-containing dopants) was studied using a modified Jet Fuel Thermal Oxidation Tester facility between 200 and 400 C. The products were analyzed by gas chromatography and mass spectrometry. The soluble products consisted mainly of n-alkanes and 1-alkenes, aldehydes, tetrahydrofuran derivatives, dodecanol and dodecanone isomers, C21-C24 alkane isomers, and dodecylhydroperoxide (ROOH) decomposition products. The major products were always the same, with and without dopants, but their distributions varied considerably. The 3,4-dimercaptotoluene and dibutylsulfide dopants added individually to n-dodecane interferred with the hydrocarbon oxidation at the alkylperoxy radical and the alkylhydroperoxide link, respectively, while the 2,5-dimethylpyrrole dopant inhibited ROOH formation. Pyridine, pyrrole, and dibenzothiophene added individually showed few significant effects.
    Keywords: PROPELLANTS AND FUELS
    Type: AIAA PAPER 87-2039
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  • 6
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    Thermal Stability of Distillate Hydrocarbon Fuels (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Thermal stability of fuels is expected to become a severe problem in the future due to the anticipated use of broadened specification and alternative fuels. Future fuels will have higher contents of heteroatomic species which are reactive constituents and are known to influence fuel degradation. To study the degradation chemistry of selected model fuels, n-dodecane and n-dodecane plus heteroatoms were aerated by bubbling air through the fuels amd stressed on a modified Jet Fuel Thermal Oxidation Tester facility operating at heater tube temperatures between 200 to 400 C. The resulting samples were fractionated to concentrate the soluble products and then analyzed using gas chromatographic and mass spectrometric techniques to quantify and identify the stable reaction intermediate and product specifically. Heteroatom addition showed that the major soluble products were always the same, with and without heteroatoms, but their distributions varied considerably.
    Keywords: PROPELLANTS AND FUELS
    Type: NASA-CR-181412 , NAS 1.26:181412
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  • 7
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    Propfan Test Assessment (PTA): Flight test report (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Propfan Test Assessment (PTA) aircraft was flown to obtain glade stress and noise data for a 2.74m (9 ft.) diameter single rotation propfan. Tests were performed at Mach numbers to 0.85 and altitudes to 12,192m (40,000 ft.). The propfan was well-behaved structurally over the entire flight envelope, demonstrating that the blade design technology was completely adequate. Noise data were characterized by strong signals at blade passage frequency and up to 10 harmonics. Cabin noise was not so high as to preclude attainment of comfortable levels with suitable wall treatment. Community noise was not excessive.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-182278 , NAS 1.26:182278 , LG89ER0026
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  • 8
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    Degradation mechanisms of n-dodecane with sulfur and nitrogen dopants during thermal stressing (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Keywords: PROPELLANTS AND FUELS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 5; 6-13
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  • 9
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    Mach 5 inlet CFD and experimental results (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An experimental research program was conducted in the NASA Lewis Research Center 10 x 10 ft supersonic wind tunnel. The 2-D inlet model was designed to study the Mach 3.0 to 5.0 speed range for an over-under turbojet plus ramjet propulsion system. The model was extensively instrumented to provide both analytical code validation data as well as inlet performance information. Support studies for the program include flow field predictions with both 3-D parabolized Navier-Stokes (PNS) and 3-D full Navier-Stokes (FNS) analytical codes. Analytical predictions and experimental results are compared.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-102317 , E-5011 , NAS 1.15:102317 , AIAA PAPER 89-2355 , Joint Propulsion Conference; Jul 10, 1989 - Jul 12, 1989; Monterey, CA; United States
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  • 10
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    Modified reaction mechanism of aerated n-dodecane liquid flowing over heated metal tubes (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The degradation mechanism of the n-dodecane was studied using a modified jet fuel thermal oxidation tester containing a sample withdrawal system as a reaction vessel. The reaction products were identified using gas chromatography and mass spectorometry. The soluble products were found to consist mainly of C5-C10 n-alkanes and 1-alkenes, C7-C10 aldehydes, tetrahydrofuran derivatives, dodecanol and dodecanone isomers, dodecyl hydroperoxide (ROOH) decomposition products, and C24 alkane isomers. The data from the experiments agreed with those of Hazlett et al. (1977). It was found that alkyl peroxide radical reactions dominate in the autooxidation temperature regime (at T not above 300 C); the dominant path is for the alkyl peroxyl radical to react bimolecularly with fuel to yield primarily alkyl hydroperoxides. The alkyl peroxide radical also undergoes self-termination and unimolecular isomerization and decomposition reactions, to yield smaller amounts of C12 alcohol plus ketone products and tetrahydrofuran derivatives, respectively.
    Keywords: PROPELLANTS AND FUELS
    Type: Journal of Energy and Fuels (ISSN 0887-0624); 2; 2 19; 205-213
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