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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 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Pressurization of cryogens: A review of current technology and its applicability to low-gravity conditions

A review of technology, history, and current status for pressurized expulsion of cryogenic tankage is presented. Use of tank pressurization to expel cryogenic fluids will continue to be studied for future spacecraft applications over a range of operating conditions in the low-gravity environment. The review examines experimental test results and analytical model development for quiescent and agitated conditions in normal-gravity, followed by a discussion of pressurization and expulsion in low-gravity. Validated, 1-D, finite difference codes exist for the prediction of pressurant mass requirements within the range of quiescent normal-gravity test data. To date, the effects of liquid sloshing have been characterized by tests in normal-gravity, but analytical models capable of predicting pressurant gas requirements remain unavailable. Efforts to develop multidimensional modeling capabilities in both normal and low-gravity have recently occurred. Low-gravity cryogenic fluid transfer experiments are needed to obtain low-gravity pressurized expulsion data. This data is required to guide analytical model development and to verify code performance.

Vandresar, N. T.↗
NASA NTRS1992

Analysis, review, and documentation of the activation data from LDEF material

Samples removed from Long Duration Exposure Facility (LDEF-1) are being studied at various laboratories to determine the specific activity(pCi/kg) produced in orbit by exposure to protons and neutrons in near-Earth orbit. These activities are being corrected for efficiency, self-attenuation, and background. The activities and associated gamma-ray spectra are being collected, analyzed, documented and reviewed by faculty and graduate students at Eastern Kentucky University. The currently available activation results have been tabulated and reviewed in this report. Approximately 500 spectra have been accumulated for future archival and analysis. The effect of the changing satellite orbit on the activation is reported herein and was calculated using more recent estimates of the flux of Van Allen belt protons.

Laird, C. E.↗
NASA NTRS1990

A review of pulse tube refrigeration

This paper reviews the development of the three types of pulse tube refrigerators: basic, resonant, and orifice types. The principles of operation are given. It is shown that the pulse tube refrigerator is a variation of the Stirling-cycle refrigerator, where the moving displacer is substituted by a heat transfer mechanism or by an orifice to bring about the proper phase shifts between pressure and mass flow rate. A harmonic analysis with phasors is described which gives reasonable results for the refrigeration power, yet is simple enough to make clear the processes which give rise to the refrigeration. The efficiency and refrigeration power are compared with those of other refrigeration cycles. A brief review is given of the research being done at various laboratories on both one- and two-stage pulse tubes. A preliminary assessment of the role of pulse tube refrigerators is discussed.

Radebaugh, Ray↗
NASA NTRS1992

Electron beams and their interactions with the ionosphere - A review of the E parallel B series

A review is presented of results from a series of experiments which began with an attempt to reflect electrons from the potential change which is thought to generate the aurora. In order to understand the experiment, this series then expanded to study beam-plasma interactions in the laboratory as well as in the ionosphere. Results from the electron reflection experiment, as well as in situ and ground-based observations of the waves generated by beam-plasma interactions will be reviewed. Measurements bearing on modifications of the ambient plasma by the beam-emitting rocket will be presented.

Kellogg, P. J.↗
NASA NTRS1992

Magnetic boundaries of the outer planets - A review

The static and dynamic characteristics of the magnetopauses of the outer planets, as well as their estimated large scale shapes, are reviewed and compared to each other and to those of the earth. Various unique features will be stressed. For example, because of the severe asymmetric nature of the main magnetic fields of Uranus and Neptune (due to significantly displaced and tilted magnetic dipole sources), their magnetospheres are (rapidly) rotating obstacles to solar wind flow, and their magnetopauses respond to that large, rapid variation. Waves or wavelike features on Uranus' boundary, and evidence for boundary layer plasmas at all of the outer planets, is reviewed. Unexpectedly, Voyager 2 encountered a magnetospheric cusp as it entered Neptune's magnetosphere. Observations of that region will be discussed, especially with regard to its structure and the apparent boundary layer plasmas around that complex boundary. Waves on the magnetopause of Saturn with periods of 5 to 30 min have been observed (as at earth). Comparisons of the estimated thicknesses of the observed magnetopauses will be made, including that of earth.

Lepping, R. P.↗
NASA NTRS1992

Pressurization of cryogens - A review of current technology and its applicability to low-gravity conditions

A review of technology, history, and current status for pressurized expulsion of cryogenic tankage is presented. Use of tank pressurization to expel cryogenic fluid will continue to be studied for future spacecraft applications over a range of operating conditions in the low-gravity environment. The review examines experimental test results and analytical model development for quiescent and agitated conditions in normal-gravity followed by a discussion of pressurization and expulsion in low-gravity. Validated, 1-D, finite difference codes exist for the prediction of pressurant mass requirements within the range of quiescent normal-gravity test data. To date, the effects of liquid sloshing have been characterized by tests in normal-gravity, but analytical models capable of predicting pressurant gas requirements remain unavailable. Efforts to develop multidimensional modeling capabilities in both normal and low-gravity have recently occurred. Low-gravity cryogenic fluid transfer experiments are needed to obtain low-gravity pressurized expulsion data. This data is required to guide analytical model development and to verify code performance.

Van Dresar, N. T.↗
NASA NTRS1992

TDWR 1991 Program Review

The topics addressed are: (1) Terminal Doppler Weather Radar (TDWR) 1991 program review; (2) TDWR demonstrations notable results/events; (3) TDWR demonstration Denver chronology; (4) overview of generic integration concepts; (5) TDWR 1991 program review; (6) Denver operation 1991; and (7) FY-92 plans.

Elmore, Kim↗
NASA NTRS1993

Review of the Shuttle vibration environment

This paper will review the Microgravity Science and Applications Division's (MSAD) program to record and analyze the Shuttle's vibration environment. This program provides microgravity experimenters with time histories of the acceleration environment during their experiments and provides information for future investigators on the expected Shuttle vibration environment. The two major elements of the program will be discussed, the Space Acceleration Measurement System (SAMS) and the Acceleration Characterization and Analysis Project (ACAP). A comparison of the acceleration measurements from five Spacelab missions will be reviewed.

Baugher, Charles R.↗
NASA NTRS1993

A review of chemically reactive turbulent flow mixing mechanisms and a new design for a low NO(x) combustor

A review of chemically reactive flow analysis is presented. Key studies are reviewed. The approaches to modeling chemically reactive flows that are discussed are PDF, conserved PDF, conserved scalar, stochastic, and mixing length. Turbulent mixing mechanisms are also discussed and a model is formulated that could be used for optimizing non-premixed gas reacting systems. Consequently, a re-examination of the NO(x) reduction concepts for nonpremixed reactants are suggested together with two new designs for low NO(x) subsonic combustor research.

Mcbeath, Giorgio↗
NASA NTRS1967

Report of Apollo 204 Review Board

The Nation's space program requires that man and machine achieve the highest capability to pursue the exploration of space. The Apollo 204 Review Board was charged with the responsibility of reviewing the circumstances surrounding the accident, reporting its findings relating to the cause of the accident, and formulating recommendations so that inherent hazards are reduced to a minimum. The Board is very concerned that its description of the defects in the Apollo Program that led to the condition existing at the time of the Apollo 204 accident will be interpreted as an indictment of the entire manned space flight program and a castigation of the many people associated with that program. This report, rather than presenting a total picture of that program, is concerned with the deficiencies uncovered.

Source record↗
NASA NTRS1993

Achievements and challenges of Space Station Freedom's safety review process

The most complex space vehicle in history, Space Station Freedom, is well underway to completion, and System Safety is a vital part of the program. The purpose is to summarize and illustrate the progress that over one-hundred System Safety engineers have made in identifying, documenting, and controlling the hazards inherent in the space station. To date, Space Station Freedom has been reviewed by NASA's safety panels through the first six assembly flights, when Freedom achieves a configuration known as Man Tended Capability. During the eight weeks of safety reviews spread out over a year and a half, over 200 preliminary hazard reports were presented. Along the way NASA and its contractors faced many challenges, made much progress, and even learned a few lessons.

Robinson, David W.↗
NASA NTRS1993

Review of betavoltaic energy conversion

Betavoltaic energy conversion refers to the generation of power by coupling a beta source to a semiconductor junction device. The theory of betavoltaic energy conversion and some past studies of the subject are briefly reviewed. Calculations of limiting efficiencies for semiconductor cells versus bandgap are presented along with specific studies for Pm-147 and Ni-63 fueled devices. The approach used for fabricating Pm-147 fueled batteries by the author in the early 1970's is reviewed. Finally, the potential performance of advanced betavoltaic power sources is considered.

Olsen, Larry C.↗
NASA NTRS1993

Cost benefits of advanced software: A review of methodology used at Kennedy Space Center

To assist rational investments in advanced software, a formal, explicit, and multi-perspective cost-benefit analysis methodology is proposed. The methodology can be implemented through a six-stage process which is described and explained. The current practice of cost-benefit analysis at KSC is reviewed in the light of this methodology. The review finds that there is a vicious circle operating. Unsound methods lead to unreliable cost-benefit estimates. Unreliable estimates convince management that cost-benefit studies should not be taken seriously. Then, given external demands for cost-benefit estimates, management encourages software enginees to somehow come up with the numbers for their projects. Lacking the expertise needed to do a proper study, courageous software engineers with vested interests use ad hoc and unsound methods to generate some estimates. In turn, these estimates are unreliable, and the cycle continues. The proposed methodology should help KSC to break out of this cycle.

Joglekar, Prafulla N.↗
NASA NTRS1994

NASA/Army Rotorcraft Transmission Research, a Review of Recent Significant Accomplishments

A joint helicopter transmission research program between NASA Lewis Research Center and the U.S. Army Research Lab has existed since 1970. Research goals are to reduce weight and noise while increasing life, reliability, and safety. These research goals are achieved by the NASA/Army Mechanical Systems Technology Branch through both in-house research and cooperative research projects with university and industry partners. Some recent significant technical accomplishments produced by this cooperative research are reviewed. The following research projects are reviewed: oil-off survivability of tapered roller bearings, design and evaluation of high contact ratio gearing, finite element analysis of spiral bevel gears, computer numerical control grinding of spiral bevel gears, gear dynamics code validation, computer program for life and reliability of helicopter transmissions, planetary gear train efficiency study, and the Advanced Rotorcraft Transmission (ART) program.

Krantz, Timothy L.↗
NASA NTRS1994

A review of vibration problems in power station boiler feed pumps

Boiler feed pump reliability and availability is recognized as important to the overall efficiency of power generation. Vibration monitoring is often used as a part of planned maintenance. This paper reviews a number of different types of boiler feed pump vibration problems describing some methods of solution in the process. It is hoped that this review may assist both designers and users faced with similar problems.

France, David↗
NASA NTRS1993

The Engineering Review Board

The NASA Engineering Review Board (ERB) is a permanent panel established to create an information infrastructure upgrade plan to support modernization efforts. The ERB looks at concepts and proposals from a system-wide perspective and identifies critical review milestones in the modernization plan. The background, role, and future directions of the ERB are described.

Hunter, Judy↗
NASA NTRS1995

Report of the Space Shuttle Management Independent Review Team

At the request of the NASA Administrator a team was formed to review the Space Shuttle Program and propose a new management system that could significantly reduce operating costs. Composed of a group of people with broad and extensive experience in spaceflight and related areas, the team received briefings from the NASA organizations and most of the supporting contractors involved in the Shuttle Program. In addition, a number of chief executives from the supporting contractors provided advice and suggestions. The team found that the present management system has functioned reasonably well despite its diffuse structure. The team also determined that the shuttle has become a mature and reliable system, and--in terms of a manned rocket-propelled space launch system--is about as safe as today's technology will provide. In addition, NASA has reduced shuttle operating costs by about 25 percent over the past 3 years. The program, however, remains in a quasi-development mode and yearly costs remain higher than required. Given the current NASA-contractor structure and incentives, it is difficult to establish cost reduction as a primary goal and implement changes to achieve efficiencies. As a result, the team sought to create a management structure and associated environment that enables and motivates the Program to further reduce operational costs. Accordingly, the review team concluded that the NASA Space Shuttle Program should (1) establish a clear set of program goals, placing a greater emphasis on cost-efficient operations and user-friendly payload integration; (2) redefine the management structure, separating development and operations and disengaging NASA from the daily operation of the space shuttle; and (3) provide the necessary environment and conditions within the program to pursue these goals.

Source record↗
NASA NTRS1994

Theory review: Line-driven instability and other causes of structure and variability in hot-star winds

The winds of the hot, luminous, OB stars are driven by the line-scattering of the star's continuum radiation flux. Several kinds of observational evidence indicate that such winds are highly structured and variable. This paper will review possible theoretical causes of such wind structure. For relatively small-scale, stochastic variability, I review the role of the strong intrinsic instability of the line-driving process itself. for larger scale structure, I describe recent efforts to examine how disturbances from the underlying, rotating star can be translated outward into propagating features in the wind.

Owocki, Stanley P.↗