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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Screen Channel Liquid Acquisition Device Outflow Tests in Liquid Hydrogen

This paper presents experimental design and test results of the recently concluded 1-g inverted vertical outflow testing of two 325x2300 full scale liquid acquisition device (LAD) channels in liquid hydrogen (LH2). One of the channels had a perforated plate and internal cooling from a thermodynamic vent system (TVS) to enhance performance. The LADs were mounted in a tank to simulate 1-g outflow over a wide range of LH2 temperatures (20.3 - 24.2 K), pressures (100 - 350 kPa), and flow rates (0.010 - 0.055 kg/s). Results indicate that the breakdown point is dominated by liquid temperature, with a second order dependence on mass flow rate through the LAD. The best performance is always achieved in the coldest liquid states for both channels, consistent with bubble point theory. Higher flow rates cause the standard channel to break down relatively earlier than the TVS cooled channel. Both the internal TVS heat exchanger and subcooling the liquid in the propellant tank are shown to significantly improve LAD performance.

Liquid Acquisition Device↗
NASA NTRS1977

Vibrations of incompressible liquid-plastic tank combinations using a series representation of the liquid

A series representation is presented of the dynamic behavior of incompressible non-viscous liquids contained in partially filled elastic shells of revolution. Using a series in which each term satisfies exactly Laplace's equation, the liquid portion of the problem becomes an integral equation on the wetted wall of the shell. Physical insight required in selecting the terms of the series is such that selection may be readily programed on a computer. Liquid-shell vibration interaction is investigated by modifying an existing shell of revolution vibration program with the series expansion of the liquid pressure loading on the wetted shell wall. Application of the modified program is demonstrated on a hemispherical tank and a realistic scaled model of a launch vehicle tank having a more complex geometry. Comparison of the present analysis with a NASTRAN finite element analysis for a hemispherical tank, and comparison with test results for a launch vehicle tank shows excellent agreement and rapid convergence of the series representation of the liquid to the true solution.

Housner, J. M.↗
NASA NTRS1985

The liquid-vapor interface of a binary liquid mixture near the consolute point

The present investigation is concerned with measurements of the reflectance of polarized light by the liquid-vapor interface above liquid mixtures of a fluorocarbon and an alcohol in the vicinity of the consolute point of the liquid mixture. The denser fluorocarbon is preferentially adsorbed at the interface. The denser fluorocarbon is preferentially adsorbed at the interface. The data are consistent with a simple model of the dielectric constant vs height profile in the interface region. Liquid mixtures of isopropanol (i-C3H7OH) and perfluoromethylcyclohexane (C7F14) near their consolute point (Tc = 363 K) are utilized in the conducted experiments. The primary quantity measured is the ellipticity as a function of temperature and liquid composition. Attention is given to details regarding the experimental techniques, model dielectric constant profiles, and the calculation of the ellipticity.

Schmidt, J. W.↗
NASA NTRS1997

Liquid-Liquid Phase Separation in Supersaturated Lysozyme Solutions and Associated Precipitate Formation/Crystallization

Using cloud point determinations, the phase boundaries (binodals) for metastable liquid-liquid (L-L) separation in supersaturated hen egg white lysozyme solutions with 3%, 5%, and 7% (wlv) NaCl at pH= 4.5 and protein concentrations c between 40 and 400 mg/ml were determined. The critical temperature for the binodal increased approximately linearly with salt concentration. The coexisting liquid phases both remained supersaturated but differed widely in protein concentration. No salt repartitioning was observed between the initial and the two separated liquid phases. After the L-L separation, due to the presence of the high protein concentration phase, crystallization occurred much more rapidly than in the initial solution. At high initial protein concentrations, a metastable gel phase formed at temperatures above the liquid binodal. Both crystal nucleation and gel formation were accelerated in samples that had been cycled through the binodal. Solutions in the gel and L-L regions yielded various types of precipitates. Based on theoretical considerations, previous observations with other proteins, and our experimental results with lysozyme, a generic phase diagram for globular proteins is put forth. A limited region in the (T,c) plane favorable for the growth of protein single crystals is delineated.

Muschol, Martin↗
NASA NTRS1999

The Three-D Flow Structures of Gas and Liquid Generated by a Spreading Flame Over Liquid Fuel

We developed a new experimental technique called: Combined laser sheet particle tracking (LSPT) and laser holographic interferometry (HI), which is capable of measuring the transient behavior of three dimensional structures of temperature and flow both in liquid and gas phases. We applied this technique to a pulsating flame spread over n-butanol. We found a twin vortex flow both on the liquid surface and deep in the liquid a few mm below the surface and a twin vortex flow in the gas phase. The first twin vortex flow at the liquid surface was observed previously by NASA Lewis researchers, while the last two observations are new. These observations revealed that the convective flow structure ahead of the flame leading edge is three dimensional in nature and the pulsating spread is controlled by the convective flow of both liquid and gas.

Tashtoush, G.↗
NASA NTRS2023

Comparison of Liquefaction Testing with Liquid Nitrogen and Liquid Oxygen

Liquid nitrogen is often used as a substitute for oxygen testing due to safety concerns, and the general similarity between their fluid properties. During the Cryogenic Fluid In-situ Liquefaction for Landers (CryoFILL) testing, an opportunity arose to compare liquid nitrogen and liquid oxygen behavior using the same test hardware in similar test conditions. Comparative testing would verify whether the system response to nitrogen and oxygen would behave in a similar manner. Tests that were investigated include system boil-off heat load determination, autogenous pressurization, cryocooler loop initiation, and cryocooler loop operations. Results from testing are shown and compared to verify that liquid nitrogen and liquid oxygen tests yield similar system responses, and that nitrogen can be used as a substitute for oxygen in developmental tests at cryogenic temperatures.

Cryogenic Fluid Management↗
NASA NTRSDate not supplied

Measuring the Liquid Helium Volume on XRISM and Predicting the Liquid Lifetime

The XRISM/Resolve instrument uses an adiabatic demagnetization refrigerator (ADR) to cool microcalorimeters to 50 mK. The cryogenic system to support the ADR consists of a liquid helium dewar and 5 cryocoolers that provide a semi-redundant system. Operation of the ADR requires either a liquid helium heat sink at 1.2 K or 4.5 K heat sink provided by a multi-stage cryocooler system. The 5 cryocoolers also provide thermal protection to the liquid helium dewar. To calculate the expected lifetime of the liquid helium system, the liquid helium volume was measured before launch and several techniques were employed to determine on-orbit boil off rate.

Michael Dipirro↗
NASA NTRS2015

Comparison of Cryogenic Flow Boiling in Liquid Nitrogen and Liquid Hydrogen Chilldown Experiments

This paper presents a comparison between experimental results from recent liquid hydrogen (LH 2 ) transfer line chilldown experiments at high Reynolds (Re) numbers versus liquid nitrogen (LN 2 ) experiments conducted at low Re numbers. Parasitic heat leak, inner wall temperatures, inner wall heat fluxes, and heat transfer coefficients are computed to compare between the two systems. Analysis of temperature traces and flow visualization indicates that the chilldown process evolves much more rapidly at higher Re numbers due to a quick transition from vapor flow to annular liquid flow and near immediate liquid contact along the pipe walls. The lower kinematic viscosity and surface tension of LH 2 , along with reduced parasitic heat leak and higher Re numbers relative to the LN 2 experiments, causes chilldown to proceed almost immediately into the nucleate boiling regime, in comparison to low Re flows where >75% of the chilldown is spent in vapor film boiling.

Cryogenic Heat Transfer Coefficient↗
NASA NTRS1973

Study of liquid-solid transition for materials processing in space. Analysis of field effects on dense liquid materials

The behavior of dense liquids near the solidification point under the influence of magnetic fields or near-zero gravity conditions were analyzed within the framework of existing liquid state models and classical field theory. The dynamic body forces which are an effect of the magnetic field on liquids are discussed. It is concluded that both magnetic fields and low gravity conditions produce an increase in the diffusion coefficient which result in an increased growth rate of crystals, and time varying magnetic fields induce eddy currents in the liquid which produce body forces and tend to disrupt convection.

Miller, R. I.↗
NASA NTRS1983

High-pressure liquid chromatography: A brief introduction and its application in analyzing the degradation of a C-ether (Thio-ether) liquid lubricant

The general principles of classical liquid chromatography and high pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analytical separation of a C-ether liquid lubricant by each technique is illustrated. A practical application of HPLC is then demonstrated by analyzing a degraded C-ether liquid lubricant from full scale, high temperature bearing tests.

Source record↗
NASA NTRS1986

Experiments on annular liquid jet instability and on the formation of liquid shells

An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Experiments are described in which such a flow is generated by an annular nozzle operated at fairly specific conditions. It is shown that periodic, axisymmetric oscillations arise spontaneously within the cylindrical sheet emerging from the nozzle and grow with such rapidity along the axial dimension that a sealing-off and encapsulation of the core gas occurs within a few jet diameters. This is closely followed by a pinchoff of the liquid between adjacent bubbles. The liquid shells set free thereby assume spherically symmetric form under capillary forces, and each contains a precisely uniform measure of gas and of liquid on account of the extremely high frequency-stability of the process. Description is given of the fluid dynamic processes by which the shells are formed, and mention is made of exploiting the instability for the production of rigid shells for technological applications.

Kendall, J. M.↗
NASA NTRS1990

Kinetics of gas-to-liquid and liquid-to-solid transfer of particles in metal-matrix composites

Analytical models for transfer of particles from gas to liquid and from liquid to solid are introduced. The model for calculation of the pushing/engulfment transition in directionally solidified particulate metal matrix composites, considers process thermodynamics, process kinetics, thermophysical properties and buoyant forces. Based on processing variables (solidification velocity and direction) and on material variables (interface energies, particle size, particle and liquid density, volume fraction of particles and particle/liquid thermal conductivity ratio) four types of behavior were predicted. Also, two numerical models for liquid-to-solid transfer are discussed, as well as the limitations of presently available models.

Stefanescu, D. M.↗
NASA NTRS1993

Transport phenomena in the crystallization of lysozyme by osmotic dewatering and liquid-liquid diffusion in low gravity

Two methods of protein crystallization, osmotic dewatering and liquid-liquid diffusion, like the vapor diffusion (hanging-drop and sessile-drop) methods allow a gradual approach to supersaturation conditions. The crystallization of hen egg-white lysozyme, an extensively characterized protein crystal, in the presence of sodium chloride was used as an experimental model with which to compare these two methods in low gravity and in the laboratory. Comparisons of crystal growth rates by the two methods under the two conditions have, to date, indicated that the rate of crystal growth by osmotic dewatering is nearly the same in low gravity and on the ground, while much faster crystal growth rates can be achieved by the liquid-liquid diffusion method in low gravity.

Todd, Paul↗
NASA NTRS1993

Foil bearing performance in liquid nitrogen and liquid oxygen

Space transfer vehicles and other power and propulsion systems require long-life turbopumps. Rolling-element bearings used in current turbopumps do not have sufficient life for these applications. Process fluid foil bearings have established long life, with exceptional reliability, over a wide range of temperatures and fluids in many high-speed turbomachinery applications. However, actual data on bearing performance in cryogenic fluids has been minimal. The National Aeronautics and Space Administration (NASA) and AlliedSignal Aerospace Systems and Equipment (ASE) have attempted to characterize the leaf-type compliant foil bearing in oxygen and nitrogen. The work performed under a joint internal research and development program between Marshall Space Flight Center (MSFC) and ASE demonstrated that the foil bearing has load capacities of at least 266 psi in liquid oxygen and 352 psi in liquid nitrogen. In addition, the bearing demonstrated a direct damping coefficient of 40 to 50 lb-sec/in. with a damping ratio of .7 to 1.4 in. liquid nitrogen using a bearing sized for upper-stage turbopumps. With the results from this testing and the years of successful use in air cycle machines and other applications, leaf-type compliant foil bearings are ready for testing in liquid oxygen turbopumps.

Genge, Gary G.↗
NASA NTRS2009

Bubble Point Measurements with Liquid Methane of a Screen Capillary Liquid Acquisition Device

Liquid acquisition devices (LADs) can be utilized within a propellant tank in space to deliver single-phase liquid to the engine in low gravity. One type of liquid acquisition device is a screened gallery whereby a fine mesh screen acts as a bubble filter and prevents the gas bubbles from passing through until a crucial pressure differential condition across the screen, called the bubble point, is reached. This paper presents data for LAD bubble point data in liquid methane (LCH4) for stainless steel Dutch twill screens with mesh sizes of 325 by 2300 and 200 by 1400 wires per inch. Data is presented for both saturated and sub-cooled LCH4, and is compared with predicted values.

Jurns, John M.↗
NASA NTRS2009

Bubble Point Measurements with Liquid Methane of a Screen Channel Capillary Liquid Acquisition Device

Liquid acquisition devices (LADs) can be utilized within a propellant tank in space to deliver single-phase liquid to the engine in low gravity. One type of liquid acquisition device is a screened gallery whereby a fine mesh screen acts as a 'bubble filter' and prevents the gas bubbles from passing through until a crucial pressure differential condition across the screen, called the bubble point, is reached. This paper presents data for LAD bubble point data in liquid methane (LCH4) for stainless steel Dutch twill screens with mesh sizes of 325 by 2300. These tests represent the first known nonproprietary effort to collect bubble point data for LCH4.

Jurns, John M.↗
NASA NTRS1974

RF gauging efforts with liquid hydrogen and liquid oxygen as applicable to subcritical space vehicle systems

The RF gauging concept is based on the interaction between a fluid dielectric medium in an enclosed metallic cavity and electromagnetic fields set up within that cavity. In RF gauging systems, the fundamental measurement relies on the interpretation of changes in the resonant RF frequencies of an enclosed tank as the mass of the propellant contained in the tank is changed. In addition to a discussion of the basic principles of operation of these systems, the study presents a description of the current breadboard implementation with typical test arrangements, along with supporting test data. The experimental testing of the RF gauging technique for liquid cryogen mass gauging indicates that this technique is a feasible approach to liquid oxygen and liquid hydrogen gauging under all attitude or reduced gravity environments.

Thompson, H. E.↗