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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Performance characteristics of gas lubricated spiral grooved journal bearings operating at high eccentricity ratios and with misalignment
Cold flow investigation and analysis of two nozzle thrust misalignment
In-orbit star tracker misalignment estimation on OAO
Causes and magnitudes of thrust misalignment of Kaufman type electron bombardment ion thrustor
Misalignment and eccentricity effect on face seal, discussing leakage dependence on phase angle
Misalignment and eccentricity effect on face seal, discussing leakage dependence on phase angle
Causes and magnitudes of thrust misalignment of Kaufman type electron bombardment ion thrustor
Magnetic element position sensing device, using misaligned electromagnets
Postflight analysis including six degree of freedom trajectory digital simulation of Aerobee 350 sounding rocket behavior under large thrust misalignment
Expressions have been derived and calculations have been made which show that combined effects lead to asymmetric interferograms and reduction in power at zero path difference. Criteria are given for estimating maximum allowable mirror misalignment.
A combination dual-spin gyroscopically stabilized device is described having a spinning rotor and a non-spinning platform. Two substantially lossless mechanical resonators, resonant at the spin frequency, are orthogonally positioned on the platform for compensation for the disturbing torque acting on the platform due to rotor misalignment.
Coupling from the EH(11) fundamental mode of a square, hollow bore waveguide laser to a square electrooptic modulator is treated. The misalignment loss that results from coupling of the laser fundamental mode into higher order modulator modes is calculated. Results are presented for loss from transverse displacement, angular tilt, and axial separation of the two elements. From these results, the alignment tolerances required to minimize loss for an intracavity modulator are found.
The article addresses the problem of assessing the sensitivity of the heat transfer rate of a Space Orbiter windward surface and boundary-layer transition data to surface features, or 'roughness elements', characteristic of randomly misaligned heat shield tiles. Selected heat shield tiles were precision-formed on the surface of a 0.0175-scale Orbiter model. Selective electroless plating and selective electrochemical etching techniques were employed. Effects of roughness on the location of boundary-layer transition were markedly influenced by the wall-to-total temperature ratios, according to wind-tunnel test results.
The magnitude of the lateral force induced by a roller, misaligned in its direction of travel is considered. Consequences of the induced lateral forces and examples of wheel suspension designs are given.
Application of the endochronic theory of viscoplasticity to creep, creep recovery, and stress relaxation at the small strain and short time range produced the following results: (1) The governing constitutive equations for constant-strain-rate stress-strain behavior, creep, creep recovery, and stress relaxation were derived by imposing appropriate constraints on the general constitutive equation of the endochronic theory. (2) A set of material constants was found which correlate strain-hardening, creep, creep recovery, and stress relaxation. (3) The theory predicts with reasonable accuracy the creep and creep recovery behaviors at short time. (4) The initial strain history prior to the creep stage affects the subsequent creep significantly. (5) A critical stress was established for creep recovery. A computer program, written for the misalignment problem is reported.
Sheet type rectangular 1100-0 aluminum specimens were tested. The creep strain at the geometric centerline of the specimen is different than that at the neutral axis, and decreases with time. The effect of misalignment, which decreases with creep time, is minimized when creep tests are conducted with long pullrods and large initial strain level (high creep stress).
The effect of coning on radial forces in face seals having angular misalignment is analyzed. Both the hydrostatic and hydrodynamic components of the resultant radial force are presented. It is shown that the displacement of the primary seal ring due to the action of radial forces is always in a direction which may cause inward pumping. However, in most cases the radial force is very small.
Annular pressure seals act as powerful hydrostatic bearings and influence the dynamic characteristics of rotating machinery. This work, using the existing concentric seal theories, provides a simple approximate method for calculation of both seal leakage and the dynamic coefficients for short seals with large eccentricity and/or misalignment of the shaft. Rotation and surface roughness effects are included for leakage and dynamic force calculation. The leakage calculations for both laminar and turbulent flow are compared with experimental results. The dynamic coefficients are compared with analytical results. Excellent agreement between the present work and published results have been observed up to the eccentricitiy ratio of 0.8.