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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Water system microbial check valve development

A residual iodine microbial check valve (RIMCV) assembly was developed and tested. The assembly is designed to be used in the space shuttle potable water system. The RIMCV is based on an anion exchange resin that is supersaturated with an iodine solution. This system causes a residual to be present in the effluent water which provides continuing bactericidal action. A flight prototype design was finalized and five units were manufactured and delivered.

Colombo, G. V.↗
NASA NTRS1978

Microbial Check Valve for Shuttle

The Microbial Check Valve (MCV) is a device developed for the Space Shuttle that prevents the transfer of viable microorganisms within water systems. The device is essentially a bed of resin material, impregnated with iodine, that kills microorganisms on contact. It prevents the cross-contamination of microorganisms from a nonpotable system into the potable water system when these systems are interconnected. In this regard, the function of the device is similar to that of the 'air gap' found in conventional one-gravity systems. Basic design data are presented including pressure drop, scaling factors, sizing criteria, and the results of challenging the device with suspensions of seven microorganisms including aerobes, anaerobes and spore formers.

Colombo, G. V.↗
NASA NTRS1980

Single-stage electrohydraulic servosystem for actuating on airflow valve with frequencies to 500 hertz

An airflow valve and its electrohydraulic actuation servosystem are described. The servosystem uses a high-power, single-stage servovalve to obtain a dynamic response beyond that of systems designed with conventional two-stage servovalves. The electrohydraulic servosystem is analyzed and the limitations imposed on system performance by such nonlinearities as signal saturations and power limitations are discussed. Descriptions of the mechanical design concepts and developmental considerations are included. Dynamic data, in the form of sweep-frequency test results, are presented and comparison with analytical results obtained with an analog computer model is made.

Webb, J. A., Jr.↗
NASA NTRS1980

Advanced microbial check valve development

A flight certified assembly identified as a Microbial Check Valve (MCV) was developed and tested. The MCV is a canister packed with an iodinated anionic exchange resin. The device is used to destroy organisms in a water stream as the water passes through the device. The device is equally effective for fluid flow in either direction and its primary method of organism removal is killing rather than filtering. The MCV was successfully developed for the space shuttle to: disinfect fuel cell water; and prevent back contamination of the stored potable water supply. One version of the device consists of a high residual iodinated resin bed that imparts approximately 2 ppm of iodine to the fuel cell water as it flows to the potable water tanks. A second version of the device consists of a low residual iodinated resin bed. One of these low residual beds is located at each use port in the potable water system for the dual purpose of removing some iodine from the potable water as it is dispensed and also to prevent back contamination of the potable supply.

Colombo, G. V.↗
NASA NTRS1980

Analysis of velocity-coupled response function data from the dual rotating valve

The results of a re-evaluation of the propellant combustion data obtained using the dual valve approach for measuring velocity-coupling characteristics of solid propellants are presented. Data analysis and testing procedures are described. The velocity response is compared to pressure-coupled response data within the context of thermal wave response theory. This comparison shows important inconsistencies which cast doubt on inferring the velocity response from pressure-coupled response functions.

Brown, R. S.↗
NASA NTRS1983

Pressure Relief Valve

Valve cap seated on an O-ring lifts to relieve positive pressure. Is attached to vacuum system by screw-on housing. Caps are loosely tied to pipe with twine or thin wire to make recovery simple.

Brabbs, T. A.↗
NASA NTRS1981

Advanced Microbial Check Valve development

The Microbial Check Valve (MCV) is a flight qualified assembly that provides bacteriologically safe drinking water for the Space Shuttle. The 1-lb unit is basically a canister packed with an iodinated ion-exchange resin. The device is used to destroy organisms in a water stream as the water passes through it. It is equally effective for fluid flow in either direction and its primary method of disinfection is killing rather than filtering. The MCV was developed to disinfect the fuel cell water and to prevent back contamination of stored potable water on the Space Shuttle. This paper reports its potential for space applications beyond the basic Shuttle mission. Data are presented that indicate the MCV is suitable for use in advanced systems that NASA has under development for the reclamation of humidity condensate, wash water and human urine.

Colombo, G. V.↗
NASA NTRS1980

Elimination of a discrete frequency acoustical phenomenon associated with the Space Shuttle main engine oxidizer valve-duct system

In the development of the Space Shuttle Main Engines, various unpredictable dynamical phenomena were experienced which resulted in engine shutdown or failures, e.g., fires. One such dynamical phenomenon consisted of an acoustical buzz at 7200 Hz in the vicinity of the main oxidizer valve. The method of isolating the buzz phenomenon, identifying the mechanism, and developing a fix to eliminate the buzz is presented together with supporting data. These data, i.e., fluctuating pressure and acceleration data, were obtained from hot firing engine tests and from liquid nitrogen flow simulation tests conducted at Marshall Space Flight Center.

Schutzenhofer, L. A.↗
NASA NTRS1982

Use of thermocapillary migration in a controllable heat valve

In accordance with the Marangoni effect, immiscible droplets in a host fluid in which a temperature gradient exists move in the direction of increasing temperature. It is proposed that this thermocapillary migration could be used to construct a 'liquid wick' that would return the condensed vapor at the condenser end of a heat pipe back to the evaporator, thus completing the fluid circuit. The droplets would be formed by capillary pressure forcing the condensate through a perforated diaphragm whose temperature would control the droplet flux, and hence the heat flux between the two ends of the heat pipe, thus making it a controllable heat valve.

Schmid, L. A.↗
NASA NTRS1985

A Positive-Shutoff Fuel Valve

Pneumatically actuated ball valve utilizes continuous contact ball seat seals and dynamic delta seals in lieu of bellows to seal against low pressure leads in fuel supply lines.

Tolpen, J.↗
NASA NTRS1985

Kick-Free Pressure Release Valve

Release valve for smoothly venting buildup of gas pressure modified to reduce kickback of mechanism during discharge.

Killgrove, T. O.↗
NASA NTRS1985

Differential Pressure Helps Seal Ball Valve

Leakage suppressed despite O-ring wear. New design eliminates leakage in vacuum selector valve on Space Shuttle waste-control subsystem. Applied to improve sealing in laboratory and industrial vacuum systems and other plumbing involving switching among lines with pressure differentials of order of 1 atmosphere (0.1 MPa).

Mangialardi, J. K.↗
NASA NTRS1984

Optical pulse generator using liquid crystal light valve

Numerical optical computing is discussed. A design for an optical pulse generator using a Hughes Liquid crystal light valve and intended for application as an optical clock in a numerical optical computer is considered. The pulse generator is similar in concept to the familiar electronic multivibrator, having a flip-flop and delay units.

Collins, S. A., Jr.↗
NASA NTRS1984

Optical flip-flops and sequential logic circuits using a liquid crystal light valve

This paper is concerned with the application of optics to digital computing. A Hughes liquid crystal light valve is used as an active optical element where a weak light beam can control a strong light beam with either a positive or negative gain characteristic. With this device as the central element the ability to produce bistable states from which different types of flip-flop can be implemented is demonstrated. In this paper, some general comments are first presented on digital computing as applied to optics. This is followed by a discussion of optical implementation of various types of flip-flop. These flip-flops are then used in the design of optical equivalents to a few simple sequential circuits such as shift registers and accumulators. As a typical sequential machine, a schematic layout for an optical binary temporal integrator is presented. Finally, a suggested experimental configuration for an optical master-slave flip-flop array is given.

Fatehi, M. T.↗
NASA NTRS1985

Voyager 0.2-lbf thruster valve assembly short pulse test report

The short pulse width testing completed on the Voyager 0.2-lbf thruster value assemblies (T/VA's) and the disassembly and inspection of T/VA S/N 020 is reported. The purpose for performing the short pulse width testing on Voyager 0.2-lbf thruster valve assemblies (T/VA's) was to determine: (1) impulse bit versus electrical pulse width; (2) impulse bit variations versus electrical pulse width; and (3) whether the short pulses decrease thruster life.

Johnson, D. R.↗
NASA NTRS1985

Joule-Thomson valves for long term service in space cryocoolers

Joule-Thomson valves for small cryocoolers have throttling passages on the order of 0.1 millimeter in diameter. Consequently, they can become plugged easily and stop the operation of the cooler. Plugging can be caused by solid particles, liquids or gases. Plugging is usually caused by the freezing of contaminant gases from the process stream. In small open loop coolers and in closed loop coolers where periodic maintenance is allowed, the problem is overcome by using careful assembly techniques, pure process gases, warm filters and cold adsorbers. A more thorough approach is required for closed loop cryocoolers which must operate unattended for long periods. This paper presents the results of an effort to solve this problem. The causes of plugging are examined, and various ways to eliminate plugging are discussed. Finally, the development of a J-T defroster is explained. It is concluded that a combination of preventive measures and a defroster will reduce the chance of cooler failure by plugging to such a degree that J-T coolers can be used for long term space missions.

Lester, J. M.↗