ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    facet.materialart.
    Unknown
    Blade Tip Rubbing Stress Prediction (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An analytical model was constructed to predict the magnitude of stresses produced by rubbing a turbine blade against its tip seal. This model used a linearized approach to the problem, after a parametric study, found that the nonlinear effects were of insignificant magnitude. The important input parameters to the model were: the arc through which rubbing occurs, the turbine rotor speed, normal force exerted on the blade, and the rubbing coefficient of friction. Since it is not possible to exactly specify some of these parameters, values were entered into the model which bracket likely values. The form of the forcing function was another variable which was impossible to specify precisely, but the assumption of a half-sine wave with a period equal to the duration of the rub was taken as a realistic assumption. The analytical model predicted resonances between harmonics of the forcing function decomposition and known harmonics of the blade. Thus, it seemed probable that blade tip rubbing could be at least a contributor to the blade-cracking phenomenon. A full-scale, full-speed test conducted on the space shuttle main engine high pressure fuel turbopump Whirligig tester was conducted at speeds between 33,000 and 28,000 RPM to confirm analytical predictions.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-184100 , NAS 1.26:184100 , RI/RD-91-114
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    Experimental study of the flow field inside a whirling annular seal (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The flow field inside a whirling annular seal has been measured using a 3-D Laser Doppler Anemometer (LDA) system. The seal investigated has a clearance of 1.27 mm, a length of 37.3 mm and is mounted on a drive shaft with a 50 percent eccentricity ratio. This results in the rotor whirling at the same speed as the shaft rotation (whirl ratio = 1.0). The seal is operated at a Reynolds number of 12000 and a Taylor number of 6300 (3600 rpm). The 3-D LDA system is equipped with a rotary encoding system which is used to produce phase averaged measurements of the entire mean velocity vector field and Reynolds stress tensor field from 0.13 mm upstream to 0.13 mm downstream of the seal. The mean velocity field reveals a highly three-dimensional flow field with large radial velocities near the inlet of the seal as well as a recirculation zone on the rotor surface. The location of maximum mean axial velocity migrates from the pressure side of the rotor at the inlet to the suction side at the exit. Turbulence production is a maximum near the seal inlet as indicated by the rapid increase of the turbulence kinetic energy (kappa). However, turbulence production and dissipation attain equilibrium fairly quickly with kappa remaining relatively constant over the last half of the seal.
    Keywords: MECHANICAL ENGINEERING
    Type: STLE Tribology Transactions (ISSN 0569-8197); 37; 2; p. 425-429
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    Bulk YBa2Cu3O(x) superconductors through pressurized partial melt growth processing (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: A novel pressurized partial melt growth process has been developed for producing large pieces of bulk Y-Ba-Cu-O superconductors. During long-time partial melt growth stage, an additional driving force for solidification is obtained by using pressurized oxygen gas. The microstructure and superconducting properties of the resulting samples were investigated. It was found that this new technique can eliminate porosity and inhomogeneity, promote large-scale grain-texturing, and improve interdomain coupling as well.
    Keywords: MECHANICAL ENGINEERING
    Type: Journal of Materials Research (ISSN 0884-2914); 7; 808-812
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    Development and performance of a three degree of freedom large motion vibration isolation mount for the KC-135 aircraft (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: Scientific microgravity experiments conducted on platforms such as the Soviet Mir space station and the U.S. Space Shuttle indicated that the microgravity environment is contaminated with disturbances which result in the reduction of a gravity quality, from micro-g to milli-g. This paper describes the vibration isolation technology developed by the Canadian Space Agency, the 1DOF Large Motion Isolation Mount (LMIM) and the 3DOF LMIM, for the KC-135 aircraft. The results of the developmental activity are presented, and the applicability of the approach taken to the Space Shuttle, Space Station Freedom, and the Mir space station is discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: AIAA PAPER 93-0574 , ; 13 p.|AIAA, Aerospace Sciences Meeting and Exhibit; Jan 11, 1993 - Jan 14, 1993; Reno, NV; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    The application of linear actuators for telescope pointing control (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A study team at MSFC has conceptually designed two lunar-based telescopes, a 16 m aperture Large Lunar Telescope (LLT) and a 4 m Cluster Telescope Experiment (CTE). The CTE serves as a technology tested for the LLT. The CTE utilizes a hexapod telescope mount to obtain a small gimbal angle that significantly extends the viewing space and observation time from that of a stationary transit telescope. This paper addresses the applicability of six linear actuators to provide limited gimbal rotation of the CTE telescope assembly. Kinematic constraint equations for the hexapod mount have been applied to a six degree-of-freedom rigid body model. Static equilibrium equations have been solved to address configuration design issues, and a feedback tracking control system has been designed and simulated.
    Keywords: MECHANICAL ENGINEERING
    Type: AAS PAPER 91-536 , AAS/AIAA Astrodynamics Conference; Aug 19, 1991 - Aug 22, 1991; Durango, CO; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    Design of a D-Strut and its application results in the JPL, MIT, and LaRC test beds (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: High damping at very low magnitudes of vibration is provided by an 'Arched Flexure' D-Strut. Five of these devices have been incorporated in JPL's CSI truss structure, and five more in MIT's interferometer test bed. Two were also temporarily installed in the LaRC CSI test structure. Damping factors in the 50 percent category are being provided at vibration motions as small as 50 nm. The 'Arched Flexure' used in the D-Strut maximizes the volumetric stiffness parameter relative to its axial stiffness. In turn, this enables high damping factors, even in a very rigid truss structure. This paper includes a presentation and discussion of both element and system test data taken at JPL, LaRC, and MIT. Also provided is a detailed description of the D-Strut, the dynamic model, and several graphs showing design parameter variations that will make it possible to evaluate the D-Strut for other applications.
    Keywords: MECHANICAL ENGINEERING
    Type: AIAA PAPER 92-2274 , AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference; Apr 13, 1992 - Apr 15, 1992; Dallas, TX; United States
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unknown
    An experimental technique for performing 3-D LDA measurements inside whirling annular seals (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: During the last several years, the Fluid Mechanics Division of the Turbomachinery Laboratory at Texas A&M University has developed a rather unique facility with the experimental capability for measuring the flow field inside journal bearings, labyrinth seals, and annular seals. The facility consists of a specially designed 3-D LDA system which is capable of measuring the instantaneous velocity vector within 0.2 mm of a wall while the laser beams are aligned almost perpendicular to the wall. This capability was required to measure the flow field inside journal bearings, labyrinth seals, and annular seals. A detailed description of this facility along with some representative results obtained for a whirling annular seal are presented.
    Keywords: MECHANICAL ENGINEERING
    Type: International Symposium on Application of Laser Techniques to Fluid Mechanics; Jul 20, 1992 - Jul 23, 1992; Lisbon; Portugal|Compressible and Incompressible Fluid Seals: Influence on Rotordynamic Response and Stability; 7 p
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unknown
    Turbulence measurements of high shear flow fields in a turbomachine seal configuration (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The mean velocity and Reynolds stress tensor throughout a whirling annular seal are presented. The data was collected with a three dimensional laser Doppler velocimeter using phase averaging. Two axial flow conditions (Re = 12,000 and 24,000) were studied at one shaft speed (Ta = 6,600). The eccentricity and whirl ratios were 50 and 100 percent, respectively. There is a region of high axial momentum in this region is higher in the low Reynolds number case due to an axial recirculation zone that occurs on the suction side of the rotor at the inlet. The recirculation zone does not occur in the high Reynolds number case. At both Reynolds numbers, there is a recirculation zone on the rotor surface in the pressure side of the inlet. This recirculation zone extends from 20 to 200 degrees rotor zenith in the tangential direction, and is one third of a clearance wide radially. The high Reynolds number recirculation zone is 1.5 mean clearances long, while the low Reynolds number zone extends 2 mean clearances downstream. When compared to previous studies, it is apparent that the tangential momentum is no greater for a seal with whirl than for one without if other parameters are constant. Areas of high tangential momentum occur in the clearance where the axial momentum is low. Average exit plane tangential velocities in the high Reynolds number case are 1.5 times greater than those in the other flow case. These results are in general agreement with predictions made by other investigators.
    Keywords: MECHANICAL ENGINEERING
    Type: 1992 Conference on Advanced Earth-To-Orbit Propulsion Technology; May 19, 1992 - May 21, 1992; Huntsville, AL; United States|Compressible and Incompressible Fluid Seals: Influence on Rotordynamic Response and Stability; 12 p
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unknown
    Experimental study of the flow field inside a whirling annular seal (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The flow field inside a whirling annular seal was measured using a 3-D Laser Doppler Anemometer (LDA) system. The seal investigated has a clearance of 1.27 mm, a length of 37.3 mm, and is mounted on a drive shaft with a 50 percent eccentricity ratio. This results in the rotor whirling at the same speed as the shaft rotation (whirl ratio = 1.0). The seal is operated at Reynolds number of 12,000 and a Taylor number of 6,300 (3,600 rpm). The 3-D LDA system is equipped with a rotary encoding system which is used to produce phase averaged measurements of the entire mean velocity vector field and Reynolds stress tensor field from 0.13 mm upstream to 0.13 mm downstream of the seal. The mean velocity field reveals a highly three dimensional flow field with large radial velocities near the inlet of the seal as well as a recirculation zone on the rotor surface. The location of maximum mean axial velocity migrates from the pressure side of the rotor at the inlet to the suction side at turbulence kinetic energy. However, turbulence production and dissipation attain equilibrium fairly quickly with remaining relatively constant over the last half of the seal.
    Keywords: MECHANICAL ENGINEERING
    Type: International Symposium on Transport Phenomena and Dynamics in Rotating Machinery; Apr 05, 1992 - Apr 08, 1992; Honolulu, HI; United States|Compressible and Incompressible Fluid Seals: Influence on Rotordynamic Response and Stability; 11 p
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unknown
    Design and Experimental Performance of a Two Stage Partial Admission Turbine, Task B.1/B.4 (1992)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: A three-inch mean diameter, two-stage turbine with partial admission in each stage was experimentally investigated over a range of admissions and angular orientations of admission arcs. Three configurations were tested in which first stage admission varied from 37.4 percent (10 of 29 passages open, 5 per side) to 6.9 percent (2 open, 1 per side). Corresponding second stage admissions were 45.2 percent (14 of 31 passages open, 7 per side) and 12.9 percent (4 open, 2 per side). Angular positions of the second stage admission arcs with respect to the first stage varied over a range of 70 degrees. Design and off-design efficiency and flow characteristics for the three configurations are presented. The results indicated that peak efficiency and the corresponding isentropic velocity ratio decreased as the arcs of admission were decreased. Both efficiency and flow characteristics were sensitive to the second stage nozzle orientation angles.
    Keywords: MECHANICAL ENGINEERING
    Type: AD-A277095 , NASA-CR-179548 , NAS 1.26:179548 , RI/RD92-214 , E-8833
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...