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  • Aircraft Propulsion and Power
  • Earth model, also for more shallow analyses !
  • 1995-1999  (36)
  • 1990-1994
  • 1950-1954  (26)
  • 1995  (36)
  • 1954  (5)
  • 1951  (21)
Collection
Years
  • 1995-1999  (36)
  • 1990-1994
  • 1950-1954  (26)
Year
  • 1
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    In:  Tectonophys., Warszawa, Icelandic Meteorological Office, Ministry for the Environment,, vol. 250, no. 4, pp. 89-112, pp. 1567, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1995
    Keywords: EUROPROBE (Geol. and Geophys. in eastern Europe) ; Earth model, also for more shallow analyses ! ; Body waves
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  • 2
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    In:  Geophys. J. Int., Warszawa, Zaklad Geofizyki Polskiej Akademii Nauk, vol. 122, no. 1-3, pp. 617-636, pp. L24306, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1995
    Keywords: Earth model, also for more shallow analyses ! ; rifting ; Tectonics ; GJI
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  • 3
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    In:  Geophys. J. Int., New York, Allerton Press, vol. 122, no. 19, pp. 108-124, pp. L01606, (ISSN: 1340-4202)
    Publication Date: 1995
    Keywords: Travel time ; Velocity ; Earth model, also for more shallow analyses ! ; GJI
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  • 4
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    In:  J. Geophys. Res., Kunming, China, Pergamon, vol. 100, no. 4, pp. 6397-6420, pp. L13613, (ISSN: 1340-4202)
    Publication Date: 1995
    Keywords: Earth model, also for more shallow analyses ! ; Velocity depth profile ; Seismology ; JGR
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  • 5
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    In:  Tectonophys., Hannover, Conseil de l'Europe, vol. 248, no. 3, pp. 71-96, pp. L17311, (ISSN 0343-5164)
    Publication Date: 1995
    Keywords: Three dimensional ; Deep seismic sounding (espec. cont. crust) ; Earth model, also for more shallow analyses ! ; Velocity depth profile
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  • 6
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    In:  Earth planet. Sci. Lett., Basel, Elsevier Science Publishers, vol. 133, no. B3, pp. 95-104, pp. B03304, (ISSN: 1340-4202)
    Publication Date: 1995
    Keywords: transmission ; Mineralogy ; Earth model, also for more shallow analyses ! ; physics ; cosmic ; radiation
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  • 7
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    In:  Rev. Geophys., Luxembourg, Conseil de l'Europe, vol. 33, no. 1, pp. 441-462, pp. L09610, (ISSN: 1340-4202)
    Publication Date: 1995
    Keywords: Inelastic ; Earth model, also for more shallow analyses ! ; Surface waves ; Attenuation
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  • 8
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    In:  Rev. Geophys., Kobe, Dec. 6-11, 1993, The Local Organizing Committee for the CRCM '93, vol. 33, no. 6695, pp. 267-309, pp. L14313, (ISSN: 1340-4202)
    Publication Date: 1995
    Keywords: CRUST ; Geochemistry ; Earth model, also for more shallow analyses ! ; Review article
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  • 9
    Publication Date: 1995
    Keywords: Deep seismic sounding (espec. cont. crust) ; Reflection seismics ; Earth model, also for more shallow analyses ! ; Velocity depth profile ; CRUST ; JGR
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  • 10
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    In:  Earth planet. Sci. Lett., Tokyo, Am. Geophys. Union, vol. 134, no. 5946, pp. 515-526, pp. 8043
    Publication Date: 1995
    Keywords: Review article ; Earth model, also for more shallow analyses ! ; geochemistry ; Allegre ; FROTH ; - ; EPSE/Oct ; 1995
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  • 11
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    In:  Physics Today, Münster, 3, vol. 48, no. 10, pp. 32-38, pp. L23301, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1995
    Keywords: Seismology ; sun ; Planetology ; Earth model, also for more shallow analyses !
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  • 12
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    American Geophysical Union
    In:  Bull., Polar Proj. OP-O3A4, Global Earth Physics: A Handbook of Physical Constants, Washington, American Geophysical Union, vol. 1, no. 4, pp. 88-103, (ISBN 0080419208)
    Publication Date: 1995
    Keywords: Review article ; Earth model, also for more shallow analyses ! ; Rheology ; Seismology
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  • 13
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    In:  Tectonophys., London, AGU, vol. 250, no. 1-4, pp. 1-14, pp. L10304, (ISSN: 1340-4202)
    Publication Date: 1995
    Keywords: Gravimetry, Gravitation ; Deep seismic sounding (espec. cont. crust) ; Reflection seismics ; EUROPROBE (Geol. and Geophys. in eastern Europe) ; Earth model, also for more shallow analyses !
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  • 14
    Publication Date: 1995
    Keywords: Deep seismic sounding (espec. cont. crust) ; Plate tectonics ; Earth model, also for more shallow analyses !
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  • 15
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    American Geophysical Union
    In:  Bull., Polar Proj. OP-O3A4, Global Earth Physics: A Handbook of Physical Constants, Washington, American Geophysical Union, vol. 1, no. XVI:, pp. 190-205, (ISBN: 3-540-23712-7)
    Publication Date: 1995
    Keywords: Review article ; Geoelectrics ; Earth model, also for more shallow analyses !
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  • 16
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    American Geophysical Union
    In:  Bull., Polar Proj. OP-O3A4, Mineral Physics & Crystallography - A Handbook of Physical Constants, Washington, D.C., American Geophysical Union, vol. 3, no. 1, pp. 227-236, (ISBN: 3-540-23712-7)
    Publication Date: 1995
    Keywords: Rheology ; Inelastic ; Modelling ; Review article ; Geothermics ; Earth model, also for more shallow analyses !
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  • 17
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    American Geophysical Union
    In:  Washington, American Geophysical Union, vol. 1, (ISBN 0-521-81734-X)
    Publication Date: 1995
    Keywords: Handbook of geophysics ; Plate tectonics ; TIDES ; Geomagnetics ; Geothermics ; Seismology ; Geoelectrics ; Earth model, also for more shallow analyses ! ; Gravimetry, Gravitation ; Paleomagnetism ; isotopes ; Geochemistry ; Oceanography ; Volcanology ; physical ; constants
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  • 18
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    In:  Geophys. J. Int., Dordrecht, American Society of Civil Engineers, vol. 121, no. B2, pp. 49-62, pp. L11307, (ISSN: 1340-4202)
    Publication Date: 1995
    Keywords: Seismology ; Hypocentral depth ; Earth model, also for more shallow analyses ! ; GJI
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  • 19
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    American Geophysical Union
    In:  Bull., Open-File Rept., Global Earth Physics: A Handbook of Physical Constants, Washington, American Geophysical Union, vol. 1, no. 1, pp. 214-224, (ISBN 1-86239-165-3, vi + 330 pp.)
    Publication Date: 1995
    Keywords: Review article ; Velocity depth profile ; Earth model, also for more shallow analyses ! ; Deep seismic sounding (espec. cont. crust)
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  • 20
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    In:  CASI
    Publication Date: 2016-06-07
    Description: The work conducted during the Summer of 1995 for the Langley Aerospace Research Summer Scholars, or LARSS, Program was a continuation of Master's Degree work being conducted for the Mechanical Engineering Department at Old Dominion University. Since this work is not yet complete, an update of progress is provided here along with a generalized background. The main emphasis of this research is to find predicted correlations in the database generated by the SHIP3D code, which modeled different scramjet combustor configurations.
    Keywords: Aircraft Propulsion and Power
    Type: Technical Reports: Langley Aerospace Research Summer Scholars; Part 1; 63-68; NASA-CR-202463
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  • 21
    Publication Date: 2019-06-28
    Description: Theoretical analyses and computer codes are being developed for predicting compressible unsteady inviscid and viscous flows through blade rows of axial-flow turbomachines. Such analyses are needed to determine the impact of unsteady flow phenomena on the structural durability and noise generation characteristics of the blading. The emphasis has been placed on developing analyses based on asymptotic representations of unsteady flow phenomena. Thus, high Reynolds number flows driven by small amplitude unsteady excitations have been considered. The resulting analyses should apply in many practical situations and lead to a better understanding of the relevant flow physics. In addition, they will be efficient computationally, and therefore, appropriate for use in aeroelastic and aeroacoustic design studies. Under the present effort, inviscid interaction and linearized inviscid unsteady flow models have been formulated, and inviscid and viscid prediction capabilities for subsonic steady and unsteady cascade flows have been developed. In this report, we describe the linearized inviscid unsteady analysis, LINFLO, the steady inviscid/viscid interaction analysis, SFLOW-IVI, and the unsteady viscous layer analysis, UNSVIS. These analyses are demonstrated via application to unsteady flows through compressor and turbine cascades that are excited by prescribed vortical and acoustic excitations and by prescribed blade vibrations. Recommendations are also given for the future research needed for extending and improving the foregoing asymptotic analyses, and to meet the goal of providing efficient inviscid/viscid interaction capabilities for subsonic and transonic unsteady cascade flows.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-4698 , R95-957907 , NAS 1.26:4698 , E-10011
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  • 22
    Publication Date: 2019-06-28
    Description: Staged combustion, such as Rich-Burn/Quick-Mix/Lean-Burn (RQL), is a viable strategy to meet nitric oxide (NO) emission goals for both stationary and propulsion gas turbine engines. A critical element of the design is the quick mixer section where the potential for NO production is high. While numerical calculations of the quick mixer under reacting conditions have been conducted, the hostile environment and lack of appropriate diagnostics have, to date, precluded experimental probing of the reacting case. As an alternative to understanding the effect of geometry and flow variations on the production of NO in the quick mixer, the present paper presents (1) a series of non-reacting parametric studies, and (2) a computational method to extrapolate the results of the non-reacting experiments to reacting conditions. The results show that the rate of NO production is highest in the immediate vicinity of the injection plane. For a given momentum flux ratio between the jets and mainstream, the most effective mixing geometry is that which mixes effectively in both (1) the plane of injection, and (2) the wall regions downstream of the plan of injection. The tailoring of the mixing is key to minimize the NO formed. As a result, the best overall mixer with respect to the minimization of NO production may depend on the system specific characteristics of the particular application.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-105639 , E-6985 , NAS 1.15:105639
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  • 23
    Publication Date: 2018-06-02
    Description: Most helicopters now in service have a transmission with a planetary design. Studies have shown that some helicopters would be lighter and more reliable if they had a transmission with a split-torque design instead. However, a split-torque design has never been used by a U.S. helicopter manufacturer because there has been no proven method to ensure equal sharing of the load among the multiple load paths. The Sikorsky/Boeing team has chosen to use a split-torque transmission for the U.S. Army's Comanche helicopter, and Sikorsky Aircraft is designing and manufacturing the transmission. To help reduce the technical risk of fielding this helicopter, NASA and the Army have done the research jointly in cooperation with Sikorsky Aircraft. A theory was developed that equal load sharing could be achieved by proper configuration of the geartrain, and a computer code was completed in-house at the NASA Lewis Research Center to calculate this optimal configuration.
    Keywords: Aircraft Propulsion and Power
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  • 24
    Publication Date: 2019-07-13
    Description: A turbine-engine-based hybrid propulsion system is described. Turbojet engines are integrated with a single-throat ramjet so as to minimize variable geometry and eliminate redundant propulsion components. The result is a simple, lightweight system that is operable from takeoff to high Mach numbers. Non-afterburning turbojets are mounted within the ramjet duct. They exhaust through a converging-diverging (C-D) nozzle into a common ramjet burner section. At low speed the ejector effect of the C-D nozzle aerodynamically isolates the relatively high pressure turbojet exhaust stream from the ramjet duct. As the Mach number increases, and the turbojet pressure ratio diminishes, the system is biased naturally toward ramjet operation. The common ramjet burner is fueled with hydrogen and thermally choked, thus avoiding the weight and complexity of a variable geometry, split-flow exhaust system. The mixed-compression supersonic inlet and subsonic diffuser are also common to both the turbojet and ramjet cycles. As the compressor face total temperature limit is approached, a two-position flap within the inlet is actuated, which closes off the turbojet inlet and provides increased internal contraction for ramjet operation. Similar actuation of the turbojet C-D nozzle flap completes the enclosure of the turbojet. Performance of the hybrid system is compared herein to that of the discrete turbojet and ramjet engines from takeoff to Mach 6. The specific impulse of the hybrid system falls below that of the non-integrated turbojet and ramjet because of ejector and Rayleigh losses. Unlike the discrete turbojet or ramjet however, the hybrid system produces thrust over the entire Mach number range. An alternate mode of operation for takeoff and low speed is also described. In this mode the C-D nozzle flap is deflected to a third position, which closes off the ramjet duct and eliminates the ejector total pressure loss.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107085 , E-9963 , NAS 1.15:107085 , 1995 Airbreathing Propulsion Subcommittee Meeting; Dec 05, 1995 - Dec 09, 1995; Tampa, FL; United States
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  • 25
    Publication Date: 2019-07-18
    Description: Detonation wave enhanced supersonic combustors such as the Oblique Detonation Wave Engine (ODWE) are attractive propulsion concepts for hypersonic flight. These engines utilize detonation waves to enhance fuel-air mixing and combustion. The benefits of wave combustion systems include shorter and lighter engines which require less cooling and generate lower internal drag. These features allow air-breathing operation at higher Mach numbers than the diffusive burning scramjet delaying the need for rocket engine augmentation. A comprehensive vehicle synthesis code has predicted the aerodynamic characteristics and structural size and weight of a typical single-stage-to-orbit vehicle using an ODWE. Other studies have focused on the use of unsteady or pulsed detonation waves. For low speed applications, pulsed detonation engines (PDE) have advantages in low weight and higher efficiency than turbojets. At hypersonic speeds, the pulsed detonations can be used in conjunction with a scramjet type engine to enhance mixing and provide thrust augmentation.
    Keywords: Aircraft Propulsion and Power
    Type: NASA Langley Workshop on Advanced Transportation Systems; Sep 26, 1995 - Sep 28, 1995; Hampton, VA; United States
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  • 26
    Publication Date: 2019-08-15
    Description: A flade exhaust nozzle for a high thrust jet engine is configured to form an acoustic shield around the core engine exhaust flowstream while supplementing engine thrust during all flight conditions, particularly during takeoff. The flade airflow is converted from an annular 360.degree. flowstream to an arcuate flowstream extending around the lower half of the core engine exhaust flowstream so as to suppress exhaust noise directed at the surrounding community.
    Keywords: Aircraft Propulsion and Power
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  • 27
    Publication Date: 2019-07-12
    Description: A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by a plurality of force transmitting mechanisms which contact the noise radiating element. Each one of the force transmitting mechanisms includes an expandable element and a spring in contact with the noise radiating element so that excitation of the element varies the spring force applied to the noise radiating element. The elements are actuated by a controller which receives input of a signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the elements and causes the spring force applied to the noise radiating element to be varied. The force transmitting mechanisms can be arranged to either produce bending or linear stiffness variations in the noise radiating element.
    Keywords: Aircraft Propulsion and Power
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  • 28
    Publication Date: 2019-07-12
    Description: A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of noise radiating structure is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating structure is tuned by a plurality of drivers arranged to contact the noise radiating structure. Excitation of the drivers causes expansion or contraction of the drivers, thereby varying the edge loading applied to the noise radiating structure. The drivers are actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the drivers, causing them to expand or contract. The noise radiating structure may be either the outer shroud of the engine or a ring mounted flush with an inner wall of the shroud or disposed in the interior of the shroud.
    Keywords: Aircraft Propulsion and Power
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  • 29
    Publication Date: 2019-07-12
    Description: A noise source for an aircraft engine active noise cancellation system in which the resonant frequency of a noise radiating element is tuned to permit noise cancellation over a wide range of frequencies. The resonant frequency of the noise radiating element is tuned by an expandable ring embedded in the noise radiating element. Excitation of the ring causes expansion or contraction of the ring, thereby varying the stress in the noise radiating element. The ring is actuated by a controller which receives input of a feedback signal proportional to displacement of the noise radiating element and a signal corresponding to the blade passage frequency of the engine's fan. In response, the controller determines a control signal which is sent to the ring, causing the ring to expand or contract. Instead of a single ring embedded in the noise radiating panel, a first expandable ring can be bonded to one side of the noise radiating element, and a second expandable ring can be bonded to the other side.
    Keywords: Aircraft Propulsion and Power
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  • 30
    Publication Date: 2019-08-16
    Description: The lean premixed-prevaporized (LPP) concept effectively meets low nitrogen oxides (NOx) emission requirements for combustors with the high inlet temperature and pressure typical of the High-Speed Civil Transport (HSCT). For the LPP system fuel-air mixture uniformity is probably the most important factor for low NOx emissions. Previous studies have suggested that the fuel-air mixture uniformity can be severely affected by changing the number and configuration of fuel injection points. Therefore, an experimental study was performed to determine how the number of fuel injection points and their arrangement affect NOx emissions from an LPP system. The NOx emissions were measured by a gas-sampling probe in a flame-tube rig at the following conditions: inlet temperature of 810 K (1000 F), rig pressure of 10 atm, reference velocity of 150 ft/s, and residence time near 0.005 s. Additionally, a focused Schlieren diagnostic technique coupled with a high speed camera was used to provide a qualitative description of the spatial flow field.
    Keywords: Aircraft Propulsion and Power
    Type: AIAA Paper 95-0729 , E-9185
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  • 31
    Publication Date: 2019-08-13
    Description: Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric balance measuring thrust and integrated pressure measurements along the length of the nozzle. Assessment of its value as a combustor performance evaluation tool will be conducted.
    Keywords: Aircraft Propulsion and Power
    Type: 1995 JANNAF Propulsion and Subcommittee Joint Meeting; Oct 22, 1995 - Oct 27, 1995; Huntsville, AL; United States
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  • 32
    Publication Date: 2019-08-15
    Description: This paper addresses the mixing of air jets into the hot, fuel-rich products of a gas turbine primary zone. The mixing, as a result, occurs in a reacting environment with chemical conversion and substantial heat release. The geometry is a crossflow confined in a cylindrical duct with side-wall injection of jets issuing from round orifices. A specially designed reactor, operating on propane, presents a uniform mixture without swirl to mixing modules consisting of 8, 9, 10, and 12 holes at a momentum-flux ratio of 57 and a jet-to-mainstream mass-flow ratio of 2.5. Concentrations of O2, CO2, CO, and HC are obtained upstream, downstream, and within the orifice plane. O2 profiles indicate jet penetration while CO2, CO, and HC profiles depict the extent of reaction. Jet penetration is observed to be a function of the number of orifices and is found to affect the mixing in the reacting system. The results demonstrate that one module (the 12-hole) produces near-optimal penetration defined here as a jet penetration closest to the module half-radius, and hence the best uniform mixture at a plane one duct radius from the orifice leading edge.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-106975 , AIAA Paper 95-3109 , E-9736 , NAS 1.15:106975 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 33
    Publication Date: 2019-08-15
    Description: An experimental investigation of the effects of jet inlet flow conditions has been conducted for the isothermal mixing of a single jet injected into a crossflow. Jet penetration and mixing was studied using planar Mie scattering to measure time-averaged jet mixture fraction distributions. The effects of 'passive' control methods such as jet 'tabs' and jet swirl are reported. Mixing effectiveness, determined using a spatial unmixedness parameter based on the variance of the mean jet concentration distributions, was compared to a baseline case of a round jet injected into a uniform crossflow. All results are compared at a jet-to-mainstream momentum-flux ratio of 8.5. In the near-field, the mixing rates are similar to, or less than, the baseline configuration using this measure of mixedness. None of the tested configurations appear to significantly augment mixing within a downstream distance of 3 diameters of an equivalent-area round orifice.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-TM-107002 , AIAA Paper 95-2998 , E-9782 , NAS 1.15:107002 , Joint Propulsion Conference and Exhibit; Jul 10, 1995 - Jul 12, 1995; San Diego, CA; United States
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  • 34
    Publication Date: 2019-08-13
    Description: This paper describes the test techniques and results from the National Aerospace Plane Government Work Package 53, the Ames Integrated Mixing Hypersonic Engine (AIMHYE) Scramjet Test program conducted in the NASA Ames 16-Inch Combustion Driven Shock Tunnel. This was a series of near full-scale scramjet combustor tests with the objective to obtain high speed combustor and nozzle data from an engine with injector configurations similar to the NASP E21 and E22a designs. The experimental test approach was to use a large combustor model (80-100% throat height) designed and fabricated for testing in the semi-free jet mode. The conditions tested were similar to the "blue book" conditions at Mach 12, 14, and 16. GWP 53 validated use of large, long test time impulse facilities, specifically the Ames 16-Inch Shock Tunnel, for high Mach number scramjet propulsion testing an integrated test rig (inlet, combustor, and nozzle). Discussion of key features of the test program will include: effects of the 2-D combustor inlet pressure profile; performance of large injectors' fueling system that included nozzlettes, base injection, and film cooling; and heat transfer measurements to the combustor. Significant instrumentation development and application efforts include the following: combustor force balance application for measurement of combustor drag for comparison with integrated point measurements of skin friction; nozzle metric strip for measuring thrust with comparison to integrated pressure measurements; and nonintrusive optical fiber-based diode laser absorption measurements of combustion products for determination of combustor performance. Direct measurements will be reported for specific test article configurations and compared with CFD solutions.
    Keywords: Aircraft Propulsion and Power
    Type: 1995 Joint JANNAF Propulsion and Subcommittee Joint Meeting; Oct 22, 1995 - Oct 27, 1995; Huntsville, AL; United States
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  • 35
    Publication Date: 2019-07-10
    Description: This report describes the design of a Low Noise ADP Research Fan stage. The fan is a variable pitch design which is designed at the cruise pitch condition. Relative to the cruise setting, the blade is closed at takeoff and opened for reverse thrust operation. The fan stage is a split flow design with fan exit guide vanes and core stators. This fan stage design was combined with a nacelle and engine core duct to form a powered fan/nacelle, subscale model. This model is intended for use in aerodynamic performance, acoustic and structural testing in a wind tunnel. The model has a 22-inch outer fan diameter and a hub-to-top ratio of 0.426 which permits the use of existing NASA fan and cowl force balance designs and rig drive system. The design parameters were selected to permit valid acoustic and aerodynamic comparisons with the PW 17-inch rig previously tested under NASA contract. The fan stage design is described in detail. The results of the design axisymmetric analysis at aerodynamic design condition are included. The structural analysis of the fan rotor and attachment is described including the material selections and stress analysis. The blade and attachment are predicted to have adequate low cycle fatigue life, and an acceptable operating range without resonant stress or flutter. The stage was acoustically designed with airfoil counts in the fan exit guide vane and core stator to minimize noise. A fan-FEGV tone analysis developed separately under NASA contract was used to determine these airfoil counts. The fan stage design was matched to a nacelle design to form a fan/nacelle model for wind tunnel testing. The nacelle design was developed under a separate NASA contract. The nacelle was designed with an axisymmetric inlet, cowl and nozzle for convenience in testing and fabrication. Aerodynamic analysis of the nacelle confirmed the required performance at various aircraft operating conditions.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-195382 , E-9125 , NAS 1.26:195382
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  • 36
    Publication Date: 2019-07-13
    Description: Concentrated solar thermal energy can be utilized in a variety of high temperature applications for both terrestrial and space environments. In each application, knowledge of the collector and absorber's heat exchange interaction is required. To understand this coupled mechanism, various concentrator types and geometries, as well as, their relationship to the physical absorber mechanics were investigated. To conduct experimental tests various parts of a 5,000 watt, thermal concentrator, facility were made and evaluated. This was in anticipation at a larger NASA facility proposed for construction. Although much of the work centered on solar thermal propulsion for an upper stage (less than one pound thrust range), the information generated and the facility's capabilities are applicable to material processing, power generation and similar uses. The numerical calculations used to design the laboratory mirror and the procedure for evaluating other solar collectors are presented here. The mirror design is based on a hexagonal faceted system, which uses a spherical approximation to the parabolic surface. The work began with a few two dimensional estimates and continued with a full, three dimensional, numerical algorithm written in FORTRAN code. This was compared to a full geometry, ray trace program, BEAM 4, which optimizes the curvatures, based on purely optical considerations. Founded on numerical results, the characteristics of a faceted concentrator were construed. The numerical methodologies themselves were evaluated and categorized. As a result, the three-dimensional FORTRAN code was the method chosen to construct the mirrors, due to its overall accuracy and superior results to the ray trace program. This information is being used to fabricate and subsequently, laser map the actual mirror surfaces. Evaluation of concentrator mirrors, thermal applications and scaling the results of the 10 foot diameter mirror to a much larger concentrator, were studied. Evaluations, recommendations and pit falls regarding the structure, materials and facility design are presented.
    Keywords: Aircraft Propulsion and Power
    Type: NASA-CR-203478 , NAS 1.26:203478
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  • 37
    Publication Date: 2019-06-27
    Description: Sound pressure levels, frequency spectrum, and jet velocity profiles are presented for an engine-afterburner combination at various values of afterburner fuel - air ratio. At the high fuel-air ratios, severe low-frequency resonance was encountered which represented more than half the total energy in the sound spectrum. At similar thrust conditions, lower sound pressure levels were obtained from a current fighter air craft with a different afterburner configuration. The lower sound pressure levels are attributed to resonance-free afterburner operation and thereby indicate the importance of acoustic considerations in afterburner design.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-E54G07
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  • 38
    Publication Date: 2019-07-11
    Description: An investigation of a decoupler and a controlled-feathering device incorporated with the YT-56A turboprop engine has been made to determine the effectiveness of these devices in reducing the high negative thrust (drag) which accompanies power failure of this type of engine. Power failures were simulated by fuel cut-off, both without either device free to operate, and with each device free to operate singly. The investigation was made through an airspeed range from 50 to 230 mph. It was found that with neither device free to operate, the drag levels realized after power failures at airspeeds above 170 mph would impose vertical tail loads higher than those allowable for the YC-130, the airplane for which the test power package was designed. These levels were reached in approximately one second. The maximum drag realized after power failure was not appreciably altered by the use of the decoupler although the decoupler did put a limit on the duration of the peak drag. The controlled-feathering device maintained a level of essentially zero drag after power failure. The use of the decoupler in the YT-56A engine complicates windmilling air-starting procedures and makes it necessary to place operating restrictions on the engine to assure safe flight at low-power conditions,
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SA54I09
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  • 39
    Publication Date: 2019-07-12
    Description: The operational characteristics of a J57-P1 turbojet engine have been investigated at altitudes between 15,000 and 66,000 feet in the Lewis altitude wind tunnel. Included in this study is a discussion of fuel nozzle coking, the altitude operating limits with and without the standard engine control, the compressor surge characteristics, and the engine starting and windmilling characteristics. Severe circumferential turbine outlet temperature gradients which occurred at high altitude as a result of fuel nozzle coking were alleviated by the manufacturer's change in the fuel flow divider schedule and in a nozzle gasket material. Compressor air bleed is required to prevent surge of the outboard compressor in the low engine speed region. The maximum altitude at which the engine was operated without the control was about 66,000 feet at 0.8 flight Mach number and at a reduced engine speed to avoid compressor surge; with the engine control in operation, the altitude operating limit is reduced to approximately 59,000 feet. The maximum altitude at which the engine was started was about 40,000 feet.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE54C31
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  • 40
    Publication Date: 2019-07-11
    Description: A method has been developed for modifying a rocket motor so that its exhaust characteristics simulate those of a turbojet engine. The analysis necessary to the design is presented along with tests from which the designs are evaluated. Simulation was found to be best if the exhaust characteristics to be duplicated were those of a turbojet engine at high altitudes and with the afterburner operative.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-L54I15
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  • 41
    Publication Date: 2019-07-12
    Description: A turbine blade with a porous stainless-steel shell sintered to a supporting steel strut has been fabricated for tests at the NACA by Federal-Mogul Corporation under contract from the Bureau of Aeronautics, Department of the Navy. The apparent permeability of this blade, on the average, more nearly approaches the values specified by the NAGA than did two strut-supported bronze blades in a previous investigation. Random variations of permeability in the present blade are substantialy greater than those of the bronze blades, but projected improvements in certain phases of the fabrication process are expected to reduce these variations.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE54D29
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  • 42
    facet.materialart.
    Unknown
    In:  Bull. Geol. Soc. Am., Milano, California Institute of Technology Pasadena, vol. 62, no. 6, pp. 427-440, pp. L24306, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1951
    Keywords: CRUST ; Earth model, also for more shallow analyses !
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  • 43
    facet.materialart.
    Unknown
    Dover Publ.
    In:  Professional Paper, Internal constitution of the earth - Physic of the earth, Dover, 439 pp., Dover Publ., vol. 7, no. XV:, pp. 382-407, (ISBN: 3-540-23712-7)
    Publication Date: 1951
    Keywords: Earth model, also for more shallow analyses ! ; Strain ; TIDES ; (The Earth's free) oscillations
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  • 44
    facet.materialart.
    Unknown
    In:  Trans., Am. Geophys. Union, Milano, California Institute of Technology Pasadena, vol. 32, no. 6, pp. 497-543, pp. L24306, (ISBN: 0534351875, 2nd edition)
    Publication Date: 1951
    Keywords: Elasticity ; Rock mechanics ; Rheology ; Fluids ; Earth model, also for more shallow analyses ! ; EOS ; BIBTEX? ; ENDNOTE?
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  • 45
    facet.materialart.
    Unknown
    Dover Publ.
    In:  Dover, 439 pp., Dover Publ., vol. 7, no. XVI:, pp. 385-389, (ISBN 0-12-305355-2)
    Publication Date: 1951
    Keywords: Handbook of geophysics ; Earth model, also for more shallow analyses !
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  • 46
    facet.materialart.
    Unknown
    Dover Publ.
    In:  Professional Paper, Internal constitution of the earth - Physic of the earth, Dover, 439 pp., Dover Publ., vol. 7, no. IX:, pp. 178-226, (ISBN: 3-540-23712-7)
    Publication Date: 1951
    Keywords: Earth model, also for more shallow analyses ! ; evolution
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  • 47
    facet.materialart.
    Unknown
    Dover Publ.
    In:  Professional Paper, Internal constitution of the earth - Physic of the earth, Dover, 439 pp., Dover Publ., vol. 7, no. VIII:, pp. 167-177, (ISBN: 3-540-23712-7)
    Publication Date: 1951
    Keywords: Earth model, also for more shallow analyses ! ; Elasticity ; TIDES ; (The Earth's free) oscillations ; Geothermics
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  • 48
    facet.materialart.
    Unknown
    Dover Publ.
    In:  Professional Paper, Internal constitution of the earth - Physic of the earth, Dover, 439 pp., Dover Publ., vol. 7, no. VIIa, pp. 438-470, (ISBN: 3-540-23712-7)
    Publication Date: 1951
    Keywords: Review article ; Earth model, also for more shallow analyses !
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  • 49
    facet.materialart.
    Unknown
    Dover Publ.
    In:  Professional Paper, Internal constitution of the earth - Physic of the earth, Dover, 439 pp., Dover Publ., vol. 7, no. VII:, pp. 150-166, (ISBN: 3-540-23712-7)
    Publication Date: 1951
    Keywords: Geothermics ; Earth model, also for more shallow analyses !
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  • 50
    facet.materialart.
    Unknown
    Dover Publ.
    In:  Professional Paper, Internal constitution of the earth - Physic of the earth, Dover, 439 pp., Dover Publ., vol. 7, no. XII:, pp. 314-339, (ISBN: 3-540-23712-7)
    Publication Date: 1951
    Keywords: CRUST ; Earth model, also for more shallow analyses !
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  • 51
    Publication Date: 2019-06-28
    Description: A comparison of the operating characteristics of 75-millimeter-bore (size 215) cylindrical-roller one-piece inner-race-riding cage-type bearings was made using a laboratory test rig and a turbojet engine. Cooling correlation parameters were determined by means of dimensional analysis, and the generalized results for both the inner- and outer-race bearing operating temperatures are compared for the laboratory test rig and the turbojet engine. Inner- and outer-race cooling-correlation curves were obtained for the turbojet-engine turbine-roller bearing with the same inner- and outer-race correlation parameters and exponents as those determined for the laboratory test-rig bearing. The inner- and outer-race turbine roller-bearing temperatures may be predicted from a single curve, regardless of variations in speed, load, oil flow, oil inlet temperature, oil inlet viscosity, oil-jet diameter or any combination of these parameters. The turbojet-engine turbine-roller-bearing inner-race temperatures were 30 to 60 F greater than the outer-race-maximum temperatures, the exact values depending on the operating condition and oil viscosity; these results are in contrast to the laboratory test-rig results where the inner-race temperatures were less than the outer-race-maximum temperatures. The turbojet-engine turbine-roller bearing, maximum outer-race circumferential temperature variation was approximately 30 F for each of the oils used. The effect of oil viscosity on inner- and outer-race turbojet-engine turbine-roller-bearing temperatures was found to be significant. With the lower viscosity oil (6x10(exp -7) reyns (4.9 centistokes) at 100 F; viscosity index, 83), the inner-race temperature was approximately 30 to 35 F less than with the higher viscosity oil (53x10(exp -7) reyns (42.8 centistokes) at 100 F; viscosity index, 150); whereas the outer-race-maximum temperatures were 12 to 28 F lower with the lower viscosity oil over the DN range investigated.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-E51I05
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  • 52
    Publication Date: 2019-06-28
    Description: Tests of two propellers having two blades and differing only in the inboard pitch distribution were made in the Langley 8-foot highspeed tunnel to determine the effect of inboard pitch distribution on propeller performance. propeller was designed for operation in the reduced velocity region ahead of an NACA cowling; the inboard pitch distribution of the modified propeller was increased for operation at or near free-stream velocities, such as would be obtained in a pusher installation. conditions covering climb, cruise, and high-speed operation. Wake surveys were taken behind the propellers in order to determine the distribution of thrust along the blades and to aid in the analysis of the results. Test results showed that the modified propeller was about 2.5 percent less efficient for a typical climb condition at all altitudes, 2 percent more efficient for one cruise condition, and 5 percent more efficient for high-speed operation. speed condition, the modified propeller showed a 6-percent loss in efficiency due to compressibility; whereas the original propeller showed an 11-percent efficiency loss due to compressiblity. The lower compressibility loss for the modified propeller resulted from the fact that the inboard sections of this propeller could operate at increased thrust loading after compressibility losses had occurred at the outboard sections.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TN-2268
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  • 53
    Publication Date: 2019-06-27
    Description: An experimental investigation was conducted to determine the cooling effectiveness of a wide variety of air-cooled turbine-blade configurations. The blades, which were tested in the turbine of a - commercial turbojet engine that was modified for this investigation by replacing two of the original blades with air-cooled blades located diametrically opposite each other, are untwisted, have no aerodynamic taper, and have essentially the same external profile. The cooling-passage configuration is different for each blade, however. The fabrication procedures were varied and often unique. The blades were fabricated using methods most suitable for obtaining a small number of blades for use in the cooling investigations and therefore not all the fabrication procedures would be directly applicable to production processes, although some of the ideas and steps might be useful. Blade shells were obtained by both casting and forming. The cast shells were either welded to the blade base or cast integrally with the base. The formed shells were attached to the base by a brazing and two welding methods. Additional surface area was supplied in the coolant passages by the addition of fins or tubes that were S-brazed. to the shell. A number of blades with special leading- and trailing-edge designs that provided added cooling to these areas were fabricated. The cooling effectiveness and purposes of the various blade configurations are discussed briefly.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-E51E23 , REPT-2203
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  • 54
    Publication Date: 2019-07-11
    Description: Strain-gages were used to measure blade vibrations causing failures in the third stage of a production 11-stage axial-flow compressor. After the serious third-stage vibration was detected, a series of investigations were conducted with second-stage vane assemblies of varying angles of incidence. Curves presented herein show the effect of varying the angle of incidence of second-stage vane assembly on third-stage rotor-blade vibration amplitude and engine performance. A minimum vibration amplitude was obtained without greatly affecting the engine performance with a second-stage vane assembly of 9deg. greater angle of incidence than the assembly normally furnished with the engine.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE51F08
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  • 55
    Publication Date: 2019-07-11
    Description: An investigation of the altitude performance characteristics of an Allison J35-A-17 turbojet engines have been conducted in an altitude chamber at the NACA Lewis laboratory. Engine performance was obtained over a range of altitudes from 20,000 to 60,000 feet at a flight Mach number of 0.62 and a range of flight Mach numbers from 0.42 to 1.22 at an altitude of 30,000 feet. The performance of the engine over the range investigated could be generalized up to an altitude of 30,000 feet. Performance of the engine at any flight Mach number in the range investigated can be predicted for those operating condition a t which critical flow exits in the exhaust nozzle with the exception of the variables corrected net thrust, and net-thrust specific fuel consumption.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-E50I15
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  • 56
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-08-13
    Description: The performance of a jet power plant consisting of a compressor and a turbine is determined by the characteristic curves of these component parts and is controllable by the characteristics of the compressor and the turbine i n relation t o each other. The normal. output, overload, and throttled load of the Jet power plant are obtained on the basis of assumed straight-line characteristics.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TM-1258
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  • 57
    Publication Date: 2019-07-11
    Description: This report presents a compilation of static sea-level data on existing or designed American and British axial-flow turbojet engines in terms of basic engine parameters such as thrust and air flow. In the data presented, changes in the over-U engine performance with time sre examined as well as the relation of the various engine parameters to each other.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-51K29
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  • 58
    Publication Date: 2019-07-12
    Description: Component data on the J35-A-23 compressor and two-stage turbine were used to determine the problems in matching the two units for operatio n in a turbojet engine. Possible operating regions were determined an d an equilibrium operating line was also determined for the assumed c onditions of zero flight speed and a jet nozzle area approximately 5. 5 percent greater than the wide-open nozzle area.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-E51H15
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  • 59
    Publication Date: 2019-07-12
    Description: A .General Electric fuel and torque regulator was tested in conjunction with a T31-3 turbine-propeller engine in the sea-level static test stand at the NACA Lewis laboratory. The engine and control were operated over the entire speed range: 11,000 rpm, nominal flight idle, to 13,000 rpm, full power. Steady-state and transient data were recorded and are presented with a description of the four control loops being used in the system. Results of this investigation indicated that single-lever control operation was satisfactory under conditions of test. Transient data presented showed that turbine-outlet temperature did overshoot maximum operating value on acceleration but that the time duration of overshoot did not exceed approximately 1 second. This temperature limiting resulted from a control on fuel flow as a function of engine speed. Speed and torque first reached their desired values 0.4 second from the time of change in power-setting lever position. Maximum speed overshoot was 3 percent.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE1H20
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  • 60
    Publication Date: 2019-07-12
    Description: At the request of the Bureau of Aeronautics, Department of the Navy, an investigation of the Westinghouse XJ34-WE-32 turbojet engine is being conducted in the NACA Lewis altitude wind tunnel to determine the steady-state and transient operating characteristics of the controlled and uncontrolled engine at various altitudes and ram pressure ratios. As part of this program, transient performance data that illustrate the operation of the engine is obtained in the form of oscillographic traces. Similar data for engine operation i n the afterburning range, covering a range of throttle settings from the minimum value giving rated speed (throttle position, 72 degrees) to full afterburning (throttle position, ll0 degrees), is presented herein. These data thus serve to indicate the transient characteristics of the engine when the throttle is advance into, withdrawn from, and moved within the afterburning range in a stepwise manner, as well as the steady-state stability of the engine during afterburning .
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE50L29
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  • 61
    Publication Date: 2019-07-12
    Description: This report summarizes the effects of fuel volatility and engine design variables on the problem of starting gas-turbine engines at sea-level and altitude conditions. The starting operation for engines with tubular combustors is considered as three steps; namely, (1) ignition of a fuel-air mixture in the combustor, (2) propagation of flame through cross-fire tubes to all combustors, and (3) acceleration of the engine from windmilling or starting speed to the operating speed range. Pertinent data from laboratory researches, single-combustor studies, and full-scale engine investigations are presented on each phase of the starting problem.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE51B02
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  • 62
    Publication Date: 2019-07-12
    Description: An investigation was conducted at the NACA Lewis laboratory to determine whether simulated porous gas-turbine blades fabricated by the Eaton Manufacturing Company of Cleveland, Ohio would be satisfactory with respect to coolant flow for application in gas-turbine engines. These blades simulated porous turbine blades by forcing the cooling air onto the blade surface through a large number of chordwise openings or slits between laminations of sheet metal or wire. This type of surface has a finite number of openings, whereas a porous surface has an almost infinite number of smaller openings for the coolant flow. The investigation showed that a blade made of sheet-metal laminations stacked on a support member that passed up through the coolant passage was completely unsatisfactory because of extremely poor coolant flow distribution over the blade surface. The flow distribution for two wire-wound blades was more uniform, but the pressure drop between the coolant supply pressure and the local pressure on the outside of the blades was too low by a factor ranging from 3 to 3.5 for the required coolant flow rates. The pressure drop could be increased by forcing the wires closer together during blade fabrication.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-RM-SE51C13
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