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  • Aeronautics (General)  (2)
  • Spacecraft Design, Testing and Performance  (2)
  • 2000-2004  (4)
  • 1985-1989
  • 2003  (4)
  • 1
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    Vibration Modal Characterization of a Stirling Convertor via Base-Shake Excitation (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The U.S. Department of Energy (DOE), Lockheed Martin (LM), Stirling Technology Company (STC), and NASA John H. Glenn Research Center (GRC) are currently developing a high-efficiency Stirling convertor for use in a Stirling Radioisotope Generator (SRG). NASA and DOE have identified the SRG for potential use as an advanced power system for future NASA Space Science missions, providing spacecraft onboard electric power for deep space missions and power for unmanned Mars rovers. Low-level, baseshake sine vibration tests were conducted on the Stirling Technology Demonstration Convertor (TDC), at NASA GRC's Structural Dynamics Laboratory, in February 2001, as part of the development of this Stirling technology. The purpose of these tests was to provide a better understanding of the TDC's internal dynamic response to external vibratory base excitations. The knowledge obtained can therein be used to help explain the success that the TDC enjoyed in its previous random vibration qualification tests (December 1999). This explanation focuses on the TDC s internal dynamic characteristics in the 50 to 250 Hz frequency range, which corresponds to the maximum input levels of its qualification random vibration test specification. The internal dynamic structural characteristics of the TDC have now been measured in two separate tests under different motoring and dynamic loading conditions: (1) with the convertor being electrically motored, under a vibratory base-shake excitation load, and (2) with the convertor turned off, and its alternator internals undergoing dynamic excitation via hammer impact loading. This paper addresses the test setup, procedure and results of the base-shake vibration testing conducted on the motored TDC, and will compare these results with those results obtained from the dynamic impact tests (May 2001) on the nonmotored TDC.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM-2003-212479 , E-14017 , AIAA Paper 2003-6096 , First International Energy Conversion Engineering Conference; Aug 17, 2003 - Aug 21, 2003; Portsmouth, VA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Formation Tetrahedron Design for Phase I of the Magnetospheric Multiscale Mission (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Magnetospheric Multiscale Mission (MMS) is a NASA mission intended to make fundamental advancements in our understanding of the Earth's Magnetosphere. There are three processes that MMS will study including magnetic reconnection, charged particle acceleration, and turbulence. There are four phases in the nominal mission and this work addresses some of the outstanding issues in phase I. The nominal phase I orbit is 1.2 x 12 R(sub e) highly elliptic orbit with four spacecraft nominally forming a regular tetrahedron. In this paper we investigate the relative dynamics of the four MMS spacecraft about an assumed reference orbit. There are several tetrahedron dimensions required in Phase I of the mission and in this work we design optimal tetrahedrons for the 10 km baseline. The performance metric used in the optimization process is directly related to the science return, and is based on an extension of previous work performed by Glassmeier. The optimizer we use is a commercially available Sequential Quadratic Programming (SQP) routine. Multiple optimal solutions are found, and we characterize how the performance of the formation varies between different regions of the reference orbit.
    Keywords: Spacecraft Design, Testing and Performance
    Type: GSFC Flight Mechanics Symposium; Oct 28, 2003 - Oct 30, 2003; Greenbelt, MD; United States
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    NASA TECHNICAL REPORTS
  • 3
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    Steady and Unsteady Flow Field Measurements Within a NASA 22-Inch Fan Model (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Results are presented of an experiment conducted to investigate possible sources of fan noise in the flow developed by a 22-in. (55.9 cm) diameter turbofan model. Flow diagnostic data were acquired to identify possible sources of both tone and broadband noise. Laser Doppler velocimetry was used to characterize the tip flows that develop within the rotor blade passages, the wake flow downstream of the rotor, and the shock waves that develop on the blades when operated at transonic relative tip speeds. Single-point hot-wire measurements were made in the rotor wake to determine the frequency content and the length scales of the flow unsteadiness. The results document the changes in the rotor wake flow with both rotor speed and axial distance downstream of the rotor. The data also show the tip flow development within the blade passage, its migration downstream, and (at high rotor speeds) its merging with the blade wake of the following blade. Data also depict the variation of the tip flow with tip clearance. LDV data obtained within the blade passages at high rotor speeds illustrate the passage-to-passage variation of the mean shock position. Spectra computed from the single-point hot-wire measurements illustrate how the energy in the flow oscillations is split between periodic and random components, and how this split varies with both radial and axial position in the rotor wake.
    Keywords: Aeronautics (General)
    Type: NASA/TM-2003-212329 , NAS 1.15:212329 , E-13924 , AIAA Paper 2002-1033 , 40th Aerospace Sciences Meeting and Exhibit; Jan 14, 2003 - Jan 17, 2003; Reno, NV; United States
    Format: application/pdf
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  • 4
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    Fan Noise Source Diagnostic Test: LDV Measured Flow Field Results (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Results are presented of an experiment conducted to investigate potential sources of noise in the flow developed by two 22-in. diameter turbofan models. The R4 and M5 rotors that were tested were designed to operate at nominal take-off speeds of 12,657 and 14,064 RPMC, respectively. Both fans were tested with a common set of swept stators installed downstream of the rotors. Detailed measurements of the flows generated by the two were made using a laser Doppler velocimeter system. The wake flows generated by the two rotors are illustrated through a series of contour plots. These show that the two wake flows are quite different, especially in the tip region. These data are used to explain some of the differences in the rotor/stator interaction noise generated by the two fan stages. In addition to these wake data, measurements were also made in the R4 rotor blade passages. These results illustrate the tip flow development within the blade passages, its migration downstream, and (at high rotor speeds) its merging with the blade wake of the adjacent (following) blade. Data also depict the variation of this tip flow with tip clearance. Data obtained within the rotor blade passages at high rotational speeds illustrate the variation of the mean shock position across the different blade passages.
    Keywords: Aeronautics (General)
    Type: NASA/TM-2003-212330 , E-13925 , NAS 1.15:212330 , AIAA Paper 2002-2431 , Eight Aeroacoustics Conference; Jun 17, 2002 - Jun 19, 2002; Breckenridge, CO; United States
    Format: application/pdf
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