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At least 199 records · Page 11

All sources NASA NTRS DOE OSTI

NASA NTRS1971

The University of Virginia superconducting magnetic suspension and balance facility.

Description of a prototype facility comprising a superconducting magnetic suspension and balance and a supersonic wind tunnel. This facility was developed with the objectives of establishing the feasibility of applying the three-component magnetic balance concept to dynamic stability studies, and investigating design concepts and parameters that are critical for extrapolation to large-scale systems. Many important design and operational aspects, as well as safety considerations, are dictated by the cryogenic nature of this advanced-technology facility. Results of initial tests demonstrate that superconductors can be utilized safely and efficiently for wind-tunnel magnetic suspensions. At the present stage of development of this facility, controlled one-dimensional support of a spherical model has been achieved.

Zapata, R. N.↗

NASA NTRS1973

Suspension of objects in magnetic and electric fields

Device has improved suspension efficiency by simulating characteristics of diamagnetic materials. Pseudodiamagnetic device suspended magnet in magnetic field at rate of 232 Kg/W. Suspension in magnetic field can be produced in two ways: magnetic source can be stationary and pseudodiamagnetic device suspended or vice versa.

Wilk, L. S.↗

NASA NTRS1973

The University of Virginia superconducting magnetic suspension and balance facility

A prototype facility comprising a superconducting magnetic suspension and balance and a supersonic wind tunnel was developed with the objectives of (1) establishing the feasibility of applying the 3-component magnetic balance concept to dynamic stability studies, and (2) investigating design concepts and parameters that are critical for extrapolation to large-scale systems. Many important design and operational aspects as well as safety considerations are dictated by the cryogenic nature of this advanced-technology facility. Results of initial tests demonstrate that super-conductors can be utilized safely and efficiently for wind tunnel magnetic suspensions. At the present stage of development of this facility, controlled one-dimensional support of a spherical model was achieved.

Zapata, R. N.↗

NASA NTRS1973

Numerical solution of equations governing longitudinal suspension line wave motion during the parachute unfurling process

Equations are presented which govern the dynamics of the lines-first parachute unfurling process, including wave motion in the parachute suspension lines. Techniques are developed for obtaining numerical solutions to the governing equations. Histories of tension at test data, and generally good agreement is observed. Errors in computed results are attributed to several areas of uncertainty, the most significant being a poorly defined boundary condition on the wave motion at the vehicle-suspension line boundary.

Poole, L. R.↗

NASA NTRS1974

Some cable suspension systems and their effects on the flexural frequencies of slender aerospace structures

The effects of several cable suspension configurations on the first free-free flexural frequency of uniform beams have been determined by experiment and analysis. The results of this study confirm that in general the larger the test vehicle the larger is the flexural frequency measurement error attributable to a given cable suspension configuration. For horizontally oriented beams representing modern aerospace vehicles of average size and flexibility, the restraining effects of all but the shortest support cables were minor. The restraining effects of support cables of moderate length attached near the base of vertically oriented vehicles were overshadowed by the effects of beam compression due to gravity.

Herr, R. W.↗

NASA NTRS1975

Development of a superconductor magnetic suspension and balance prototype facility for studying the feasibility of applying this technique to large scale aerodynamic testing

The basic research and development work towards proving the feasibility of operating an all-superconductor magnetic suspension and balance device for aerodynamic testing is presented. The feasibility of applying a quasi-six-degree-of freedom free support technique to dynamic stability research was studied along with the design concepts and parameters for applying magnetic suspension techniques to large-scale aerodynamic facilities. A prototype aerodynamic test facility was implemented. Relevant aspects of the development of the prototype facility are described in three sections: (1) design characteristics; (2) operational characteristics; and (3) scaling to larger facilities.

Zapata, R. N.↗

NASA NTRS1975

The Annular Suspension and Pointing (ASP) system for space experiments and predicted pointing accuracies

An annular suspension and pointing system consisting of pointing assemblies for coarse and vernier pointing is described. The first assembly is attached to a carrier spacecraft (e.g., the space shuttle) and consists of an azimuth gimbal and an elevation gimbal which provide 'coarse' pointing. The second or vernier pointing assembly is made up of magnetic actuators of suspension and fine pointing, roll motor segments, and an instrument or experiment mounting plate around which is attached a continuous annular rim similar to that used in the annular momentum control device. The rim provides appropriate magnetic circuits for the actuators and the roll motor segments for any instrument roll position. The results of a study to determine the pointing accuracy of the system in the presence of crew motion disturbances are presented. Typical 3 sigma worst-case errors are found to be of the order of 0.001 arc-second.

Anderson, W. W.↗

NASA NTRS1976

One-dimensional wave propagation in particulate suspensions

One-dimensional small-amplitude wave motion in a two-phase system consisting of an inviscid gas and a cloud of suspended particles is analyzed using a continuum theory of suspensions. Laplace transform methods are used to obtain several approximate solutions. Properties of acoustic wave motion in particulate suspensions are inferred from these solutions.

Rochelle, S. G.↗

NASA NTRS1981

Analysis and simulation of a magnetic bearing suspension system for a laboratory model annular momentum control device

A linear analysis and the results of a nonlinear simulation of a magnetic bearing suspension system which uses permanent magnet flux biasing are presented. The magnetic bearing suspension is part of a 4068 N-m-s (3000 lb-ft-sec) laboratory model annular momentum control device (AMCD). The simulation includes rigid body rim dynamics, linear and nonlinear axial actuators, linear radial actuators, axial and radial rim warp, and power supply and power driver current limits.

Groom, N. J.↗

NASA NTRS1982

The stress system generated by an electromagnetic field in a suspension of drops

The stress generated in a suspension of drops in the presence of a uniform electric field and a pure straining motion, taking into account that the magnetohydrodynamic effects are dominant was calculated. It was found that the stress generated in the suspension depended on the direction of the applied electric field, the dielectric constants, the vicosity coefficients, the conductivities, and the permeabilities of fluids inside and outside the drops. The expression of the particle stress shows that for fluids which are good conductors and poor dielectrics, especially for larger drops, magnetohydrodynamic effects end to reduce the dependence on the direction of the applied electric field.

Erdogan, M. E.↗

NASA NTRS1982

Design concepts and cost studies for magnetic suspension and balance systems

The application of superconducting magnets for suspension and balance of wind tunnel models was studied. Conceptual designs are presented for magnetic suspension and balance system (MSBS) configurations compatible with three high Reynolds number cases representing specified combinations of test conditions and model sizes. Concepts in general met initially specified performance requirements such as duty cycle, force and moment levels, model angular displacement and positioning accuracy with nominal design requirements for support subsystems. Other performance requirements, such as forced model sinusoidal oscillations, and control force magnitude and frequency, were modified so as to alleviate the magnitude of magnet, power, and cryogenic design requirements.

Bloom, H. L.↗

NASA NTRS1981

Vibration attenuation using magnetic suspension isolation

The paper derives the vibration transfer function for a magnetic suspension in generic form, with specific reference to the Annular Suspension and Pointing System for Shuttle payloads. It is shown that a magnetically suspended pointer can exhibit considerably improved dynamic stability over conventional means, particularly at high frequencies and for transient disturbances. The amount of improvement to be anticipated is quantified to allow first-cut assessments for specific applications.

Hamilton, B. J.↗

NASA NTRS1982

Stability of erythrocyte suspensions layered on stationary and flowing liquids

The apparent stability of erythrocyte suspensions layered on stationary and flowing Ficoll solutions was studied considering the effects of particle concentration, type and size, and the different flow rates of the particle suspensions and chamber liquid. The data from the flowing system were empirically fitted and, when extrapolated to zero chamber liquid flow rate, gave values comparable to the data from the stationary system, thus confirming the validity of the data and our approach to obtain that data.

Omenyi, S. N.↗

NASA NTRS1984

Rheological study of clay-kaolin aqueous suspensions

Rheological characteristics of clay-kaolin aqueous suspensions were studied by a rotational viscometer to correlate their behavior with the properties of ceramic slips for casting containing quartz, feldspars, and other nonplastic materials. In particular, the effects of the different amounts of dry materials and deflocculant (mixture 1:1 of Na2CO3 and Na2SiO3) and of temperatures on the shear-time-dependent properties of suspensions were examined.

Lapasin, R.↗

NASA NTRS1984

Deflocculation of clay suspensions using sodium polyacrylates

Rheological properties of elutriated kaolin suspensions deflocculated by Na polyacrylate (DAC 3 and DAC 4) were studied and compared to those deflocculated by the conventional Na2CO3 water and glass and imported Dispex N40. The deflocculating effect of Na polyacrylate was comparable to that of Dispex N40. The optimum amounts of Na polyacrylate were determined for suspensions based on 5-type kaolin. The Na polyacrylate can be successfully used for decreasing the water content of ceramic slips for casting and spray drying.

Jedlicka, P.↗

NASA NTRS1984

Flow properties of concentrated suspensions

The viscosity and flow behavior of a concentrated suspension, with special emphasis on fresh concrete containing a superplasticizer, is analyzed according to Newton's law of viscosity. The authors interpreted Newton's law in a new way, and explain non-Newton flow from Newton's law. The outline of this new theory is given. Viscosity of suspensions, and the effect of dispersants are analyzed.

Hattori, K.↗

NASA NTRS1984

Influence of suspension hypokinesia on rat soleus muscle

Hindlimb hypokinesia was induced in rats by the Morey method to characterize the response of the soleus muscle. Rats suspended for 1-4 wk exhibited continuous and significant declines in soleus mass, function, and contractile duration. Soleus speeding was in part explained by an alteration in fiber type. The normal incidence of 70-90 percent type I fibers in the soleus muscle was reduced after 4 wk of suspension to 50 percent or less in 9 of 11 rats. A significant decline in type I myosin isozyme content occurred without a change in that of type II. Other observed histochemical changes were characteristic of denervation. Consistent with soleus atrophy, there was a significant increase in lysosomal (acid) protease activity. One week of recovery after a 2-wk suspension was characterized by a return to values not significantly different from control for muscle wet weights, peak contraction force, one-half relaxation time, and type I myosin. Persistent differences from control were observed in maximal rate of tension development, contraction time, and denervation-like changes.

Templeton, G. H.↗

NASA NTRS1984

Electrokinetic potential and stability of SiC suspensions in electrolyte solutions

The dependence of zeta potential on pH of an aqueous Si carbide suspension was studied by an electroosmosis method. The effect of pH on the Si carbide electrical double layer is attributed to the participation of H and OH ions in the surface dissociation reactions of weak acid OH groups on an oxidized carbide surface. Maximum stability of the suspensions was observed at maximum negative zeta potentials.

Eremenko, B. V.↗