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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Normalizing parameters for the critical flow rate of simple fluids through nozzles

It is shown that two-phase critical nozzle flow of simple fluids almost obeys the principle of corresponding states. Quantum fluid departures from the principle are resolved as a function of temperature for para-hydrogen and helium. The critical flow rates are normalized, using a normalizing parameter for which the critical flow rates of all simple fluids reduce to a single isothermal curve. The expression obtained for the normalizing parameter is shown to provide good agreement with the experiment for the critical flow rates of nitrogen, oxygen, and para-hydrogen.

Hendricks, R. C.↗
NASA NTRS2011

Columbus Payloads Flow Rate Anomalies

The Columbus Active Thermal Control System (ATCS) is the main thermal bus for the pressurized racks working inside the European laboratory. One of the ATCS goals is to provide proper water flow rate to each payload (P/L) by controlling actively the pressure drop across the common plenum distribution piping. Overall flow measurement performed by the Water Pump Assembly (WPA) is the only flow rate monitor available at system level and is not part of the feedback control system. At rack activation the flow rate provided by the system is derived on ground by computing the WPA flow increase. With this approach, several anomalies were raised during these 3 years on-orbit, with the indication of low flow rate conditions on the European racks FSL, BioLab, EDR and EPM. This paper reviews the system and P/Ls calibration approach, the anomalies occurred, the engineering evaluation on the measurement approach and the accuracy improvements proposed, the on-orbit test under evaluation with NASA and finally discusses possible short and long term solutions in case of anomaly confirmation.

Quaranta, Albino↗
NASA NTRS1983

A method of predicting flow rates required to achieve anti-icing performance with a porous leading edge ice protection system

An analytical method was developed for predicting minimum flow rates required to provide anti-ice protection with a porous leading edge fluid ice protection system. The predicted flow rates compare with an average error of less than 10 percent to six experimentally determined flow rates from tests in the NASA Icing Research Tunnel on a general aviation wing section.

Kohlman, D. L.↗
NASA NTRS1974

Electromagnetic flow rate meter

A liquid metal, whose flow rate is to be determined, is directed through a chamber made of electrically-insulating material on which there is impressed a magnetic field perpendicular to the direction of flow of the liquid metal. The magnetic field is made to increase in strength in a downstream direction of the flow of liquid metal. At least a pair of electrodes are disposed in the chamber traversely and perpendicular to the direction of flow and an ammeter is connected between the electrodes. Electrodes may be disposed in the top or the bottom of the chamber and each may be segmented. Oppositely disposed electrodes may be used with at least one dividing wall extending from each electrode to cause reversal of the direction of flow of the liquid metal. The magnetic field may be provided by electromagnets or permanent magnets such as shaded pole permanent magnets.

Banks, B. A.↗
NASA NTRS1974

Normalizing parameters for the critical flow rate of simple fluids through nozzles

The two-phase critical flow rate for the simple fluids of methane, nitrogen, oxygen, and argon were normalized using the parameter G* = the square root of (rho sub c x P sub c/Z sub c). The values of G* are given and the question of how to apply this procedure to normalize the critical flow rates of the quantum fluids para-hydrogen and helium was addressed. Experimental data for p-hydrogen, reduced pressures to 4.5 and reduced temperatures from 0.87, were analyzed.

Hendricks, R. C.↗
NASA NTRS2013

Mass Flow Rate and Isolation Characteristics of Injectors for Use with Self-Pressurizing Oxidizers in Hybrid Rockets

Self-pressurizing rocket propellants are currently gaining popularity in the propulsion community, particularly in hybrid rocket applications. Due to their high vapor pressure, these propellants can be driven out of a storage tank without the need for complicated pressurization systems or turbopumps, greatly minimizing the overall system complexity and mass. Nitrous oxide (N2O) is the most commonly used self pressurizing oxidizer in hybrid rockets because it has a vapor pressure of approximately 730 pounds per square inch (5.03 megapascals) at room temperature and is highly storable. However, it can be difficult to model the feed system with these propellants due to the presence of two-phase flow, especially in the injector. An experimental test apparatus was developed in order to study the performance of nitrous oxide injectors over a wide range of operating conditions. Mass flow rate characterization has been performed to determine the effects of injector geometry and propellant sub-cooling (pressurization). It has been shown that rounded and chamfered inlets provide nearly identical mass flow rate improvement in comparison to square edged orifices. A particular emphasis has been placed on identifying the critical flow regime, where the flow rate is independent of backpressure (similar to choking). For a simple orifice style injector, it has been demonstrated that critical flow occurs when the downstream pressure falls sufficiently below the vapor pressure, ensuring bulk vapor formation within the injector element. It has been proposed to leverage the insensitivity of critical mass flow rate to downstream pressure as a means of preventing the occurrence of feed system coupled combustion instabilities in hybrid rockets utilizing nitrous oxide. Additionally, observations indicate that the existence of two-phase flow can attenuate pressure fluctuations traveling upstream through the injector, providing a degree of isolation between the feed line and downstream pressure disturbances. In consideration of safety, carbon dioxide (CO2) has been used as an analog to nitrous oxide in many of these studies. It has been observed experimentally that carbon dioxide serves as a good analog to nitrous oxide in both the single-phase and two-phase flow regimes.

Oxidizer↗
NASA NTRS1987

Measurements of Flow Rate and Trajectory of Aircraft Tire-Generated Water Spray

An experimental investigation was conducted at the NASA Langley Research Center to measure the flow rate and trajectory of water spray generated by an aircraft tire operating on a flooded runway. Tests were conducted in the Hydrodynamics Research Facility and made use of a partial airframe and a nose tire from a general aviation aircraft. Nose tires from a commercial transport aircraft were also used. The effects of forward speed, tire load, and water depth on water spray patterns were evaluated by measuring the amount and location of water captured by an array of tubes mounted behind the test tire. Water ejected from the side of the tire footprint had the most significant potential for ingestion into engine inlets. A lateral wake created on the water surface by the rolling tire can dominate the shape of the spray pattern as the distance aft of the tire is increased. Forward speed increased flow rates and moved the spray pattern inboard. Increased tire load caused the spray to become less dense. Near the tire, increased water depths caused flow rates to increase. Tests using a fuselage and partial wing along with the nose gear showed that for certain configurations, wing aerodynamics can cause a concentration of spray above the wing.

Daugherty, Robert H.↗
NASA NTRS1966

Device accurately measures and records low gas-flow rates

Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

Branum, L. W.↗
NASA NTRS1983

Pressure difference-flow rate variation in a femoral artery branch casting of man for steady flow

In-vitro, steady flow in a casting of the profunda femoris branch of the femoral artery of man was studied by measuring pressure differences in the main lumen and also in the branch over a large Reynolds number range from 200 to 1600. Effects of viscous and inviscid flows in this femoral artery branch were demonstrated quantitatively. The critical ratio of the flow rate in the branch to the upstream main lumen in this casting was found to be 0.4, above which the inviscid flow analysis indicated a pressure rise and below which it yielded a pressure drop in the main lumen across the branch junction. Pressure rises were experimentally found to occur both in the main lumen and in the branch for certain ranges of the aforementioned ratio.

Cho, Y. I.↗
NASA NTRS1993

Use of optical edge and optical flow rate: Information in the perception and control of ground velocity

Previous research (Denton, 1980; Larish & Flach, 1990; Owen, Wolpert, & Warren, 1984; Awe & Johnson, 1989) suggests that people will use one or both of two optical variables as information for the perception and/or regulation of ground velocity. The first variable, global optical flow rate (FR), reflects the angular optical speed, and is proportional to the observer's ground velocity scaled in altitude units, i.e. velocity divided by altitude. Therefore, flow rate is a reliable indicator of ground velocity only under the condition of constant altitude. The second variable, optical edge rate (ER), reflects ground velocity as the frequency at which the optically specified ground edges pass across some optical region. Therefore, edge rate is an accurate indicator of ground velocity when altitude varies, but not when texture density varies. Since both flow rate and edge rate can vary independently of forward ground velocity, accurate ground-velocity control may depend upon using the best optical variable.

Johnson, Walter W.↗
NASA NTRS1977

Gravity flow rate of solids through orifices and pipes

Lock-hopper systems are the most common means for feeding solids to and from coal conversion reactor vessels. The rate at which crushed solids flow by gravity through the vertical pipes and valves in lock-hopper systems affects the size of pipes and valves needed to meet the solids-handling requirements of the coal conversion process. Methods used to predict flow rates are described and compared with experimental data. Preliminary indications are that solids-handling systems for coal conversion processes are over-designed by a factor of 2 or 3.

Gardner, J. F.↗
NASA NTRS1973

The dynamic behavior of articulated pipes conveying fluid with periodic flow rate.

The plane motion of two rigid, straight articulated pipes conveying fluid is examined. In contrast to previous work, the flow rate is not taken as constant, but is allowed to have small periodic oscillations about a mean value, as would be expected in a pump-driven system. It is shown that in the presence of such disturbances, both parametric and combination resonances are possible. When the system can also admit loss of stability by static buckling or by flutter, it is found that the presence of small periodic disturbances constitutes a destabilizing effect. Floquet theory and converging infinite determinant expansions are used to illustrate a basic difference between systems which lose stability by divergence and those that lose stability by flutter. An algebraic criterion is obtained for the minimum amplitude of flow-rate oscillation required for the system to be affected by the presence of small disturbances.

Bohn, M. P.↗
NASA NTRS1965

Volumetric system calibrates meters for large flow rates

Volumetric system calibrates meters used for large liquid flow rates. The system employs trip probes and equipment to time the flow of liquid from a tare vessel into a calibrated vessel. This calibration system is used in the petroleum and chemical industries.

Source record↗
NASA NTRS1966

Flowmeter measures low gas-flow rates

Positive-displacement flowmeter measures low gas-flow rates by gaging the time required for a slug of mercury to pass between two reference levels in a tube of known volume.

Wells, F. E.↗