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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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476 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Transient liquid-crystal technique used to produce high-resolution convective heat-transfer-coefficient maps

In this transient technique the preheated isothermal model wall simulates the classic one-dimensional, semi-infinite wall heat transfer conduction problem. By knowing the temperature of the air flowing through the model, the initial temperature of the model wall, and the surface cooling rate measured at any location with time (using the fast-response liquid-crystal patterns recorded on video tape), the heat transfer coefficient can be calculated for the color isothermal pattern produced. Although the test was run transiently, the heat transfer coefficients are for the steady-state case. The upstream thermal boundary condition was considered to be isothermal. This transient liquid-crystal heat-transfer technique was used in a transient air tunnel in which a square-inlet, 3-to-1 exit transition duct was placed. The duct was preheated prior to allowing room temperature air to be suddenly drawn through it. The resulting isothermal contours on the duct surfaces were revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record was made of the temperature and time data for all points on the duct surfaces during each test. The duct surfaces were uniformly heated using two heating systems: the first was an automatic temperature-controlled heater blanket completely surrounding the test duct like an oven, and the second was an internal hot-air loop through the inside of the test duct. The hot-air loop path was confined inside the test duct by insulated heat dams located at the inlet and exit ends of the test duct. A recirculating fan moved hot air into the duct inlet, through the duct, out of the duct exit, through the oven, and back to the duct inlet. The temperature nonuniformity of the test duct model wall was held very small. Test results are reported for two inlet Reynolds numbers of 200,000 and 1,150,000 (based on the square-inlet hydraulic diameter) and two free-stream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 20 percent (using a grid), which is typical of real engine conditions.

Hippensteele, Steven A.↗
NASA NTRS1996

STS-72 Space Shuttle Mission Report

The STS-72 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Reusable Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSME) systems performance during the seventy-fourth flight of the Space Shuttle Program, the forty-ninth flight since the return-to-flight, and the tenth flight of the Orbiter Endeavour (OV-105). In addition to the Orbiter, the flight vehicle consisted of an ET that was designated ET-75; three Block I SSME's that were designated as serial numbers 2028, 2039, and 2036 in positions 1, 2, and 3, respectively; and two SRB's that were designated BI-077. The RSRM's, designated RSRM-52, were installed in each SRB and the individual RSRM's were designated as 36OW052A for the left SRB, and 36OW052B for the right SRB. Appendix A lists the sources of data, both formal and informal, that were used to prepare this report. The primary objectives of this flight were to retrieve the Japanese Space Flyer Unit (JSFU) and deploy and retrieve the Office of Aeronautics and Space Technology-Flyer (OAST-Flyer). Secondary objectives were to perform the operations of the Shuttle Solar Backscatter Ultraviolet (SSBUV/A) experiment, Shuttle Laser Altimeter (SLA)/get-Away Special (GAS) payload, Physiological and Anatomical Rodent Experiment/National Institutes of Health-Cells (STL/NIH-C) experiment, Protein Crystal Growth-Single Locker Thermal Enclosure System (PCG-STES) experiment, Commercial Protein Crystal Growth (CPCG) payload and perform two extravehicular activities (EVA's) to demonstrate International Space Station Alpha (ISSA) assembly techniques). Appendix B provides the definition of acronyms and abbreviations used throughout the report. All times during the flight are given in Greenwich mean time (GMT) and mission elapsed time (MET).

Fricke, Robert W., Jr.↗
NASA NTRS2003

Nanolayered Features of Collagen-like Peptides

We have been investigating collagen-like model oligopeptides as molecular bases for complex ordered biomimetic materials. The collagen-like molecules incorporate aspects of native collagen sequence and secondary structure. Designed modifications to native primary and secondary structure have been incorporated to control the nanostructure and microstructure of the collagen-like materials produced. We find that the collagen-like molecules form a number of lyotropic rod liquid crystalline phases, which because of their strong temperature dependence in the liquid state can also be viewed as solvent intercalated thermotropic liquid crystals. The liquid crystalline phases formed by the molecules can be captured in the solid state by drying off solvent, resulting in solid nanopatterned (chemically and physically) thermally stable (to greater than 100 C) materials. Designed sequences which stabilize smectic phases have allowed a variety of nanoscale multilayered biopolymeric materials to be developed. Preliminary investigations suggest that chemical patterns running perpendicular to the smectic layer plane can be functionalized and used to localize a variety of organic, inorganic, and organometallic moieties in very simple multilayered nanocomposites. The phase behavior of collagen-like oligopeptide materials is described, emphasizing the correlation between mesophase, molecular orientation, and chemical patterning at the microscale and nanoscale. In many cases, the textures observed for smectic and hexatic phase collagens are remarkably similar to the complex (and not fully understood) helicoids observed in biological collagen-based tissues. Comparisons between biological morphologies and collagen model liquid crystalline (and solidified materials) textures may help us understand the molecular features which impart order and function to the extracellular matrix and to collagen-based mineralized tissues. Initial studies have utilized synthetic collagen-like peptides while future work will also focus on similar sequences generated via genetic engineering methods.

Valluzzi, Regina↗
NASA NTRS1994

STS-62 Space Shuttle mission report

The STS-62 Space Shuttle Program Mission Report summarizes the Payload activities as well as the Orbiter, External Tank (ET), Solid Rocket Booster (SRB), Redesigned Solid Rocket Motor (RSRM), and the Space Shuttle main engine (SSHE) systems performance during the sixty-first flight of the Space Shuttle Program and sixteenth flight of the Orbiter vehicle Columbia (OV-102). In addition to the Orbiter, the flight vehicle consisted of an ET designated as ET-62; three SSME's which were designated as serial numbers 2031, 2109, and 2029 in positions 1, 2, and 3, respectively; and two SRB's which were designated BI-064. The RSRM's that were installed in each SRB were designated as 360L036A (lightweight) for the left SRB, and 36OWO36B (welterweight) for the right SRB. This STS-62 Space Shuttle Program Mission Report fulfills the Space Shuttle Program requirement as documented in NSTS 07700, Volume 8, Appendix E. That document requires that each major organizational element supporting the Program report the results of its hardware evaluation and mission performance plus identify all related in-flight anomalies. The primary objectives of the STS-62 mission were to perform the operations of the United States Microgravity Payload-2 (USMP-2) and the Office of Aeronautics and Space Technology-2 (OAST-2) payload. The secondary objectives of this flight were to perform the operations of the Dexterous End Effector (DEE), the Shuttle Solar Backscatter Ultraviolet/A (SSBUV/A), the Limited Duration Space Environment Candidate Material Exposure (LDCE), the Advanced Protein Crystal Growth (APCG), the Physiological Systems Experiments (PSE), the Commercial Protein Crystal Growth (CPCG), the Commercial Generic Bioprocessing Apparatus (CGBA), the Middeck Zero-Gravity Dynamics Experiment (MODE), the Bioreactor Demonstration System (BDS), the Air Force Maui Optical Site Calibration Test (AMOS), and the Auroral Photography Experiment (APE-B).

Fricke, Robert W., Jr.↗
NASA NTRS2007

Circuit and Method for Communication Over DC Power Line

A circuit and method for transmitting and receiving on-off-keyed (OOK) signals with fractional signal-to-noise ratios uses available high-temperature silicon- on-insulator (SOI) components to move computational, sensing, and actuation abilities closer to high-temperature or high-ionizing radiation environments such as vehicle engine compartments, deep-hole drilling environments, industrial control and monitoring of processes like smelting, and operations near nuclear reactors and in space. This device allows for the networking of multiple, like nodes to each other and to a central processor. It can do this with nothing more than the already in-situ power wiring of the system. The device s microprocessor allows it to make intelligent decisions within the vehicle operational loop and to effect control outputs to its associated actuators. The figure illustrates how each node converts digital serial data to OOK 18-kHz in transmit mode and vice-versa in receive mode; though operations at lower frequencies or up to a megahertz are within reason using this method and these parts. This innovation s technique modulates a DC power bus with millivolt-level signals through a MOSFET (metal oxide semiconductor field effect transistor) and resistor by OOK. It receives and demodulates this signal from the DC power bus through capacitive coupling at high temperature and in high ionizing radiation environments. The demodulation of the OOK signal is accomplished by using an asynchronous quadrature detection technique realized by a quasi-discrete Fourier transform through use of the quadrature components (0 and 90 phases) of the carrier frequency as generated by the microcontroller and as a function of the selected crystal frequency driving its oscillator. The detected signal is rectified using an absolute-value circuit containing no diodes (diodes being non-operational at high temperatures), and only operational amplifiers. The absolute values of the two phases of the received signal are then summed and hard limited (digitized) by comparing them to a reference level and are then input into a microprocessor as a serial bit stream. The quasi-discrete Fourier transform is performed in high-temperature components (operational amplifiers, analog switches, resistors, and capacitors). The demodulated signal is a serial data stream that is input to the UART (universal asynchronous receiver transmitter) receiver pin of the microprocessor. The OOK of the carrier frequency uses the output of the UART pin as an enabling signal that drives the gate of the MOSFET. Logic low bits enable the carrier frequency (realized by using the 0 phase signal from the microcontroller, though either phase may be used) to be DC-coupled to the power supply bus through a current-limiting resistor mounted between the MOSFET drain and the supply rail. The presence of logic lows on the power supply rail is realized by carrier bursts while logic highs are realized by the absence of bursts.

Krasowski, Michael J.↗
NASA NTRS1997

Experimental Investigation of Jet Impingement Heat Transfer Using Thermochromic Liquid Crystals

Jet impingement cooling of a hypersonic airfoil leading edge is experimentally investigated using thermochromic liquid crystals (TLCS) to measure surface temperature. The experiment uses computer data acquisition with digital imaging of the TLCs to determine heat transfer coefficients during a transient experiment. The data reduction relies on analysis of a coupled transient conduction - convection heat transfer problem that characterizes the experiment. The recovery temperature of the jet is accounted for by running two experiments with different heating rates, thereby generating a second equation that is used to solve for the recovery temperature. The resulting solution requires a complicated numerical iteration that is handled by a computer. Because the computational data reduction method is complex, special attention is paid to error assessment. The error analysis considers random and systematic errors generated by the instrumentation along with errors generated by the approximate nature of the numerical methods. Results of the error analysis show that the experimentally determined heat transfer coefficients are accurate to within 15%. The error analysis also shows that the recovery temperature data may be in error by more than 50%. The results show that the recovery temperature data is only reliable when the recovery temperature of the jet is greater than 5 C, i.e. the jet velocity is in excess of 100 m/s. Parameters that were investigated include nozzle width, distance from the nozzle exit to the airfoil surface, and jet velocity. Heat transfer data is presented in graphical and tabular forms. An engineering analysis of hypersonic airfoil leading edge cooling is performed using the results from these experiments. Several suggestions for the improvement of the experimental technique are discussed.

Dempsey, Brian Paul↗
NASA NTRS2003

Research Center for Optical Physics: Education and Technology for the 21st Century

During the past eleven years since its inception, RCOP has excelled in its two primary goals: 1) training of the scientists and engineers needed for the twenty-first century with special emphasis on underrepresented citizens and 2) research and technological development in areas of relevance to NASA. In the category of research training, as of May 2003, RCOP produced 36 Bachelors degrees, 25 Masters degrees, and 13 Doctoral degrees. Of these, all 36 Bachelors degrees, 16 of the Masters degrees and 9 of the Doctoral degrees were awarded to African Americans. Four of the Doctoral graduates and one of the Masters graduates are working at NASA Field Centers. RCOP has also provided research experiences to 130 undergraduate students and 22 high school students through a number of outreach programs held during the summer and the academic year. RCOP has also been crucial to the development of the Ph.D. program in physics at Hampton University by providing high quality research training and technical electives required for a Doctoral degree in physics. RCOP has also excelled in research and technological development. Since 1992, RCOP researchers have leveraged over 8 million dollars in additional research funding, published 152 papers in refereed journals and proceedings, and given 125 presentations at refereed international conferences in the United States and eight other countries. RCOP also developed numerous collaborations with other research centers, universities and industries. In recognition of this outstanding work, RCOP is the first research center in the United States invited to join the Joint Open Laboratory for Laser Crystals and Precise Laser Systems headed by Dr. Alexander Kaminiskii of the Russian Academy of Sciences.

Source record↗
NASA NTRS1997

Organometallic Polymeric Conductors

For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. Many aerospace applications require a combination of properties. Thus, hybrid films made from polyimides or other engineering resins are of primary interest, but only if conductivities on the same order as those obtained with a polystyrene base could be obtained. Hence, a series of experiments was performed to optimize the conductivity of polyimide-based composite films. The polyimide base chosen for this study was Kapton. 3-MethylThiophene (3MT) was used for the conductive phase. Three processing variables were identified for producing these composite films, namely time, temperature, and oxidant concentration for the in situ oxidation. Statistically designed experiments were used to examine the effects of these variables and synergistic/interactive effects among variables on the electrical conductivity and mechanical strength of the films. Multiple linear regression analysis of the tensile data revealed that temperature and time have the greatest effect on maximum stress. The response surface of maximum stress vs. temperature and time (for oxidant concentration at 1.2 M) is shown. Conductivity of the composite films was measured for over 150 days in air at ambient temperature. The conductivity of the films dropped only half an order of magnitude in that time. Films aged under vacuum at ambient temperature diminished slightly in conductivity in the first day, but did not change thereafter. An experimental design approach will be applied to maximize the efficiency of the laboratory effort. The material properties (initial and long term) will also be monitored and assessed. The experimental results will add to the existing database for electrically conductive polymer materials. Attachments: 1) Synthesis Crystal Structure, and Polymerization of 1,2:5,6:9,10-Tribenzo-3,7,11,13-tetradehydro(14) annulene. 2) Reinvestigation of the Photocyclization of 1,4-Phenylene Bis(phenylmaleic anhydride): Preparation and Structure of (5)Helicene 5,6:9,10-Dianhydride. 3) Preparation and Structure Charecterization of a Platinum Catecholate Complex Containing Two 3-Ethynyltheophone Groups. and 4) Rigid-Rod Polymers Based on Noncoplanar 4,4'-Biphenyldiamines: A Review of Polymer Properties vs Configuration of Diamines.

Youngs, Wiley J.↗