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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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At least 505 records · Page 28

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NASA NTRS1978

Integral equation formulation for probe corrected far-field reconstruction from measurements on a cylinder

A method has been developed for far-field evaluation from measurements taken on a cylinder. The antenna and probe fields are represented by superpositions of plane waves, and two integral equations are derived whose functions are the elevation and azimuthal components of the antenna pattern. The known components are the measurements taken by either two probes or a single probe with two geometrical orientations. The convolutional nature of the integral equations makes Fourier analysis techniques applicable to a straightforward solution and an efficient computational procedure. Good agreement has been found between experimental and reconstructed patterns for both nominal and cross polarized field components.

Borgiotti, G. V.↗

NASA NTRS1978

The free shear layer tone phenomenon and probe interference

The reported investigation shows that the hot-wire probe induces stable upstream oscillations in a free shear layer, similar to the jet edge tone mechanism. This effect can be significant also in measurements involving large-scale organized structure, conditional sampling, space-time correlation, and convection velocity, when a reference or indicator probe may be used near the origin of the free shear layer. It appears that even in a free shear layer without any wedge, an object in the flow sufficiently downstream can also provide feedback to the flow upstream. A description is given of the edge-tone phenomenon which is observed when a thin slit jet impinges on a plane wedge. Attention is given to the free shear layer tone induced by a hot-wire probe, the free shear layer tone phenomenon, and shear layer tone eigenvalues and eigenfunctions.

Hussain, A. K. M. F.↗

NASA NTRS1977

A subcutaneous channeling probe for implanting long leads

The channeling probe described in the present paper was designed to overcome surgical problems of the type that were encountered when a multichannel radio transmitter had to be implanted in a cow. The probe was made of a flexible but sufficiently stiff 9.5-mm-diam nylon rod, consisting of 46-cm sections for convenience in sterilization and surgical handling. Stainless steel sleaves reinforced the threaded connecting joints. At one end, arrowhead-shaped channeling heads could be attached to produce wide channels for large sensors. The other end was tapered for narrow channels. Postoperative problems were not encountered in the use of this probe in cows, sheep, and dogs.

Lund, G. F.↗

NASA NTRS1978

Saturn orbiter dual probe mission

The described Saturn orbiter dual probe mission and spacecraft combines three systems into a multi-purpose Saturn exploration package. The spacecraft consists of: (1) Saturn orbiter; (2) Saturn probe; and (3) Titan probe or lander. This single spacecraft provides the capability to conduct in situ measurements of the Saturn and Titan atmospheres, and, possibly the Titan surface, as well as a variety of remote sensing measurements. The remote sensing capabilities will be used to study the surfaces, interiors and environments of Saturn's satellites, the rings of Saturn, Saturn's magnetosphere, and synoptic properties of Saturn's atmosphere.

Rudd, R. P.↗

NASA NTRS1978

Outer planet probe missions, designs and science

The similarities and differences of atmosphere entry probe mission designs and sciences appropriate to certain solar system objects, are reviewed. Candidate payloads for Saturn and Titan probes are suggested. Significant supporting research and technology efforts are required to develop mission-peculiar technology for probe exploration of the Saturnian system.

Colin, L.↗

NASA NTRS1979

Calorimeter probes for measuring high thermal flux

Expendable, slug-type calorimeter probes were developed for measuring high heat-flux levels of 10-30 kW/sq cm in electric-arc jet facilities. The probes were constructed with thin tungsten caps mounted on Teflon bodies. The temperature of the back surface of the tungsten cap is measured, and its time rate of change gives the steady-state absorbed heat flux as the calorimeter probe heats to destruction when inserted into the arc jet. Design, construction, test, and performance data are presented.

Russell, L. D.↗

NASA NTRS1979

Effect of number of probes and their orientation on the calculation of several compressor face distortion descriptors

A study was performed to determine the effects of the number and position of total pressure probes on the calculation of five compressor face distortion descriptors. This study used three sets of 320 steady state total pressure measurements that were obtained with a special rotating rake apparatus in wind tunnel tests of a mixed-compression inlet. The inlet was a one third scale model of the inlet on a YF-12 airplane, and it was tested in the wind tunnel at representative flight conditions at Mach numbers above 2.0. The study shows that large errors resulted in the calculation of the distortion descriptors even with a number of probes that were considered adequate in the past. There were errors as large as 30 and -50 percent in several distortion descriptors for a configuration consisting of eight rakes with five equal-area-weighted probes on each rake.

Stoll, F.↗

NASA NTRS1979

Study of entry and landing probes for exploration of Titan

Saturn's largest moon, Titan, is a totally unique planetary body which is certain to yield exciting new phenomena. Current information is lacking in detail to distinguish between a thin methane rich atmosphere and a thick nitrogen rich atmosphere. Therefore, both the thin and thick atmospheric models were used for the study of various Titan probe classes described in this report. The technical requirements, conceptual design, science return, schedule, cost and mission implications of three probe classes that could be used for exploration of Titan are defined. The three probe classes were based on a wide range of exploration mission possibilities.

Source record↗

NASA NTRS1978

Sealing scientific probes against deep space and the Venusian environment A tough job

The Pioneer Venus mission evolved from studies conducted during the late 1960s and early 1970s. It was found that a need existed for low cost orbiters and landers to explore the planet. The considered mission was to be accomplished with six separate vehicles arriving at Venus nearly simultaneously in mid-December 1978. The probes are designed to survive entry and descent into the atmosphere. A description is presented of the approaches used to maintain sealing integrity for the large and small probes under the constraints imposed by the harsh Venusian environment. Attention is given to probe vehicle configuration, pressure vessel sealing requirements, material and configuration considerations, permanent seals, separable seals, development problems, and aspects of seal testing.

Pokras, J.↗

NASA NTRS1979

Structure of the atmosphere of Venus up to 110 kilometers - Preliminary results from the four Pioneer Venus entry probes

Each of the four Pioneer Venus probes carried instruments to measure the structure of the atmosphere, both below the cloud deck and above it to an altitude of at least 120 km. Preliminary results are presented on lower-atmosphere structure, thermal contrasts, and atmospheric stability. Altitudes derived from the data are given along with the temperature profile from 67 to 105 km, derived from the first analysis of the entry data from the north probe. All four probes lost temperature data at the 640 K level, which is at an altitude of about 12 to 14 km. Values of temperature and pressure at touchdown are presented in a table. The pressure differences imply terrain elevation differences at the landing sites. Above 40 km, the measured profile moves from near-adiabatic toward the theoretical profile for radiative equilibrium.

Seiff, A.↗

NASA NTRS1978

Electron paramagnetic resonance studies of slowly tumbling vanadyl spin probes in nematic liquid crystals

The purposes of this vanadyl spin probe study are threefold: (1) to establish when the breakdown of motionally narrowed formulas occurs; (2) to analyze the experimental vanadyl EPR line shapes by the stochastic Lioville method as developed by Polnaszek et al. (1973) for slow tumbling in an anisotropic liquid; and (3) to compare the vanadyl probe study results with those of Polnaszek and Freed (1975). Spectral EPR line shapes are simulated for experimental spectra of vanadyl acetylacetonate (VOAA) in nematic liquid crystal butyl p-(p-ethoxyphenoxycarbonyl) phenyl carbonate (BEPC) and Phase V of EM laboratories. It is shown that the use of typical vanadyl complexes as spin probes for nematic liquid crystals simplifies the theoretical analysis and the subsequent interpretation. Guidelines for the breakdown of motionally narrowed formulas are established. Both the slow tumbling aspects and the effects of non-Brownian rotation should be resolved in order to extract quantitative information about molecular ordering and rotational mobility.

Bruno, G. V.↗

NASA NTRS1979

The Saturn Orbiter Dual Probe mission concept

This paper presents the results of a mission design study for NASA of the next Saturn mission to follow Voyager. The Saturn Orbiter Dual Probe (SO2P) mission combines three spacecraft - a Saturn orbiter, a Saturn probe, and a Titan probe/lander - into a multipurpose Saturn exploration package. The mission is to conduct a survey from orbit around Saturn and to physically probe bodies in the Saturnian system, the first such mission to do so. The mission has many possible options including: combining solar electric propulsion with earth gravity assist, assembling of IUS stages in orbit, and aerocapture at Titan to insert into Saturn orbit.

Roberts, P. H., Jr.↗

NASA NTRS1979

Displacement probes with self-contained exciting medium

A transducer that combines a noncontacting displacement probe with a self-contained target is described. The target is held in position against a vibrating surface by a housing which also supports the noncontacting probe. The target vibrates with the surface and the probe senses the vibrations of the target.

Miserentino, R.↗

NASA NTRS1980

Wake flowfields for Jovian probe

The wake flow field developed by the Galileo probe as it enters the Jovian atmosphere was modeled. The wake produced by the probe is highly energetic, yielding both convective and radiative heat inputs to the base of the probe. A component mathematical model for the inviscid near and far wake, the viscous near and far wake, and near wake recirculation zone was developed. Equilibrium thermodynamics were used for both the ablation and atmospheric species. Flow fields for three entry conditions were calculated. The near viscous wave was found to exhibit a variable axial pressure distribution with the neck pressure approximately three times the base pressure. Peak wake flow field temperatures were found to be in proportion to forebody post shock temperatures.

Engel, C. D.↗

NASA NTRS1980

Titan probe technology assessment and technology development plan study

The need for technology advances to accomplish the Titan probe mission was determined by defining mission conditions and requirements and evaluating the technology impact on the baseline probe configuration. Mission characteristics found to be technology drivers include (1) ten years dormant life in space vacuum; (2) unknown surface conditions, various sample materials, and a surface temperature; and (3) mission constraints of the Saturn Orbiter Dual Probe mission regarding weight allocation. The following areas were identified for further development: surface sample acquisition system; battery powered system; nonmetallic materials; magnetic bubble memory devices, and the landing system. Preentry science, reliability, and weight reduction and redundancy must also be considered.

Castro, A. J.↗

NASA NTRS1980

Surface reflections of Pioneer Venus probe signals

As the four Pioneer Venus probes fell within the atmosphere toward the surface of Venus, each of them transmitted a radio signal directly to earth. Because of the relatively broad antenna beamwidth of these small probes, some of the transmitted power went down to the surface of Venus. This paper reports the discovery that the radio signals scattered off the surface are not only detectable but that their characteristics can be determined with a surprising degree of certainty. From these characteristics one can determine parameters of the Venusian atmospheric winds and of the surface that promise to be useful. Most of the scattered energy is that which originally radiated from the probes in a near-horizontal direction; the downward-directed radiation is detectable but much weaker. Refraction in the atmosphere of Venus clearly plays a significant role in establishing both the strength of scatter and its Doppler shift.

Croft, T. A.↗

NASA NTRS1980

Comparisons of subsonic drag estimates derived from Pioneer Venus probes flight data with wind-tunnel results

Subsonic drag coefficients have been obtained from flight data for the Pioneer Venus multiprobes. The technique used to extract the information from the data consisted of utilizing in situ pressure and temperature measurements. Analysis of the major model parameter error sources indicates overall error levels of five percent or less in the flight values of the drag coefficient. Comparisons of the flight coefficients with preflight wind-tunnel test data showed generally good agreement except for the Sounder descent probe configuration. To preclude atmospheric phenomena as a possible explanation of this difference, additional wind-tunnel tests were performed on the Sounder descent probe. Special attempts were made to duplicate the probe geometry for tests in a high Reynolds number environment in order to achieve as realistic model and flight conditions as practical. Preliminary results from this testing in the NASA LaRC Low Turbulence Pressure Tunnel produced a drag coefficient of 0.68 at 0 deg angle of attack which is within the expected accuracy limits of the flight derived drag coefficient value of 0.72 + or - 0.04, thus eliminating atmospheric phenomena as the explanation for the initial difference.

Blanchard, R. C.↗

NASA NTRS1982

Multipressure and Temperature Probe

Aerodynamic probe is a small cylinder tube holding a network of tiny tubes leading to various ports. Six parameters are recorded simultaneously with little interference with aerodynamic flow. Two tubes connected by a hot-wire tungsten probe sense steady and fluctuating components of total and static pressures; the feedbacks from these tubes are input into differential-pressure sensors to measure fluctuating components of the pressures. Data are recorded by instruments at the back end of the probe.

Raman, K. R.↗