Sample records for minimum pressure drop

  1. Automatic safety rod for reactors. [LMFBR

    DOEpatents

    Germer, J.H.

    1982-03-23

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  2. Automatic safety rod for reactors

    DOEpatents

    Germer, John H.

    1988-01-01

    An automatic safety rod for a nuclear reactor containing neutron absorbing material and designed to be inserted into a reactor core after a loss-of-core flow. Actuation is based upon either a sudden decrease in core pressure drop or the pressure drop decreases below a predetermined minimum value. The automatic control rod includes a pressure regulating device whereby a controlled decrease in operating pressure due to reduced coolant flow does not cause the rod to drop into the core.

  3. Intercooler cooling-air weight flow and pressure drop for minimum drag loss

    NASA Technical Reports Server (NTRS)

    Reuter, J George; Valerino, Michael F

    1944-01-01

    An analysis has been made of the drag losses in airplane flight of cross-flow plate and tubular intercoolers to determine the cooling-air weight flow and pressure drop that give a minimum drag loss for any given cooling effectiveness and, thus, a maximum power-plant net gain due to charge-air cooling. The drag losses considered in this analysis are those due to (1) the extra drag imposed on the airplane by the weight of the intercooler, its duct, and its supports and (2) the drag sustained by the cooling air in flowing through the intercooler and its duct. The investigation covers a range of conditions of altitude, airspeed, lift-drag ratio, supercharger-pressure ratio, and supercharger adiabatic efficiency. The optimum values of cooling air pressure drop and weight flow ratio are tabulated. Curves are presented to illustrate the results of the analysis.

  4. Effects of pressure drop and superficial velocity on the bubbling fluidized bed incinerator.

    PubMed

    Wang, Feng-Jehng; Chen, Suming; Lei, Perng-Kwei; Wu, Chung-Hsing

    2007-12-01

    Since performance and operational conditions, such as superficial velocity, pressure drop, particles viodage, and terminal velocity, are difficult to measure on an incinerator, this study used computational fluid dynamics (CFD) to determine numerical solutions. The effects of pressure drop and superficial velocity on a bubbling fluidized bed incinerator (BFBI) were evaluated. Analytical results indicated that simulation models were able to effectively predict the relationship between superficial velocity and pressure drop over bed height in the BFBI. Second, the models in BFBI were simplified to simulate scale-up beds without excessive computation time. Moreover, simulation and experimental results showed that minimum fluidization velocity of the BFBI must be controlled in at 0.188-3.684 m/s and pressure drop was mainly caused by bed particles.

  5. 40 CFR 63.9921 - What are the installation, operation and maintenance requirements for my monitors?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... operating limits in § 63.9890(b) for pressure drop and scrubber water flow rate, you must install, operate...) For the pressure drop CPMS, you must: (i) Locate the pressure sensor(s) in or as close to a position... sensitivity of 0.5 inch of water or a transducer with a minimum measurement sensitivity of 1 percent of the...

  6. Correlations of catalytic combustor performance parameters

    NASA Technical Reports Server (NTRS)

    Bulzan, D. L.

    1978-01-01

    Correlations for combustion efficiency percentage drop and the minimum required adiabatic reaction temperature necessary to meet emissions goals of 13.6 g CO/kg fuel and 1.64 g HC/kg fuel are presented. Combustion efficiency was found to be a function of the cell density, cell circumference, reactor length, reference velocity, and adiabatic reaction temperature. The percentage pressure drop at an adiabatic reaction temperature of 1450 K was found to be proportional to the reference velocity to the 1.5 power and to the reactor length. It is inversely proportional to the pressure, cell hydraulic diameter, and fractional open area. The minimum required adiabatic reaction temperature was found to increase with reference velocity and decrease with cell circumference, cell density and reactor length. A catalyst factor was introduced into the correlations to account for differences between catalysts. Combustion efficiency, the percentage pressure drop, and the minimum required adiabatic reaction temperature were found to be a function of the catalyst factor. The data was from a 12 cm-diameter test rig with noble metal reactors using propane fuel at an inlet temperature of 800 K.

  7. 40 CFR Table 3 to Subpart Dddd of... - Model Rule-Operating Limits for Wet Scrubbers

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Scrubbers 3 Table 3 to Subpart DDDD of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...—Model Rule—Operating Limits for Wet Scrubbers For these operating parameters You must establish these... intermittent units) a Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop...

  8. 40 CFR Table 3 to Subpart Dddd of... - Model Rule-Operating Limits for Wet Scrubbers

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Scrubbers 3 Table 3 to Subpart DDDD of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...—Model Rule—Operating Limits for Wet Scrubbers For these operating parameters You must establish these... intermittent units) a Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop...

  9. 40 CFR Table 3 to Subpart Ffff of... - Model Rule-Operating Limits for Incinerators and Wet Scrubbers

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Incinerators and Wet Scrubbers 3 Table 3 to Subpart FFFF of Part 60 Protection of Environment ENVIRONMENTAL...—Model Rule—Operating Limits for Incinerators and Wet Scrubbers As stated in § 60.3023, you must comply... units. a 2. Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop or...

  10. 40 CFR Table 3 to Subpart Ffff of... - Model Rule-Operating Limits for Incinerators and Wet Scrubbers

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Incinerators and Wet Scrubbers 3 Table 3 to Subpart FFFF of Part 60 Protection of Environment ENVIRONMENTAL...—Model Rule—Operating Limits for Incinerators and Wet Scrubbers As stated in § 60.3023, you must comply... units. a 2. Pressure drop across the wet scrubber or amperage to wet scrubber Minimum pressure drop or...

  11. 40 CFR Table 3 to Subpart Ec of... - Operating Parameters To Be Monitored and Minimum Measurement and Recording Frequencies

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... scrubber followed by fabric filter Wet scrubber Dry scrubber followed by fabric filter and wet scrubber... flow rate Hourly 1×hour ✔ ✔ Minimum pressure drop across the wet scrubber or minimum horsepower or amperage to wet scrubber Continuous 1×minute ✔ ✔ Minimum scrubber liquor flow rate Continuous 1×minute...

  12. Impacts of coronary artery eccentricity on macro-recirculation and pressure drops using computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Poon, Eric; Thondapu, Vikas; Barlis, Peter; Ooi, Andrew

    2017-11-01

    Coronary artery disease remains a major cause of mortality in developed countries, and is most often due to a localized flow-limiting stenosis, or narrowing, of coronary arteries. Patients often undergo invasive procedures such as X-ray angiography and fractional flow reserve to diagnose flow-limiting lesions. Even though such diagnostic techniques are well-developed, the effects of diseased coronary segments on local flow are still poorly understood. Therefore, this study investigated the effect of irregular geometries of diseased coronary segments on the macro-recirculation and local pressure minimum regions. We employed an idealized coronary artery model with a diameter of stenosis of 75%. By systematically adjusting the eccentricity and the asymmetry of the coronary stenosis, we uncovered an increase in macro-recirculation size. Most importantly, the presence of this macro-recirculation signifies a local pressure minimum (identified by λ2 vortex identification method). This local pressure minimum has a profound effect on the pressure drops in both longitudinal and planar directions, which has implications for diagnosis and treatment of coronary artery disease. Supported by Australian Research Council LP150100233 and National Computational Infrastructure m45.

  13. 40 CFR 65.84 - Operating requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-tight means that the pressure in a truck or railcar tank will not drop more than 750 pascals (0.11 pound per square inch) within 5 minutes after it is pressurized to a minimum of 4,500 pascals (0.65 pound...

  14. 76 FR 9449 - National Emission Standards for Hazardous Air Pollutants: Gold Mine Ore Processing and Production...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-17

    ... chemistry, scrubber pressure drop, and scrubber inlet gas temperature hourly. The final rule does not... pressure) and inlet gas temperature to be based on the minimum flow rate (or line pressure) or maximum inlet gas temperature established during the initial performance test. It also includes two additional...

  15. Numerical Modeling of Surface and Volumetric Cooling using Optimal T- and Y-shaped Flow Channels

    NASA Astrophysics Data System (ADS)

    Kosaraju, Srinivas

    2017-11-01

    The layout of T- and V-shaped flow channel networks on a surface can be optimized for minimum pressure drop and pumping power. The results of the optimization are in the form of geometric parameters such as length and diameter ratios of the stem and branch sections. While these flow channels are optimized for minimum pressure drop, they can also be used for surface and volumetric cooling applications such as heat exchangers, air conditioning and electronics cooling. In this paper, an effort has been made to study the heat transfer characteristics of multiple T- and Y-shaped flow channel configurations using numerical simulations. All configurations are subjected to same input parameters and heat generation constraints. Comparisons are made with similar results published in literature.

  16. Condensation heat transfer and pressure drop of R-410A in a 7.0 mm O.D. microfin tube at low mass fluxes

    NASA Astrophysics Data System (ADS)

    Kim, Nae-Hyun

    2016-12-01

    R-410A condensation heat transfer and pressure drop data are provided for a 7.0 mm O.D. microfin tube at low mass fluxes (50-250 kg/m2 s). The heat transfer coefficient of the microfin tube shows a minimum behavior with the mass flux. At a low mass flux, where flow pattern is stratified, condensation induced by surface tension by microfins overwhelms condensation induced by shear, and the heat transfer coefficient decreases as mass flux increases. At a high mass flux, where flow pattern is annular, condensation induced by shear governs the heat transfer, and the heat transfer coefficient increases as mass flux increases. The pressure drop of the microfin tube is larger than that of the smooth tube at the annular flow regime. On the contrary, the pressure drop of the smooth tube is larger than that of the microfin tube at the stratified flow regime.

  17. External Catalyst Breakup Phenomena

    DTIC Science & Technology

    1976-06-01

    catalyst particle can cause high internal pressures which result in particle destruction. Analytical results suggest rhat erosion effects from solid...mechanisms. * Pressure Forces. High G loadings and bed pressure drops should be avoided. Bed pre-loads should be kept at a minimum value. Thruster...5.2.7.1 Failure Theories ............................ 243 5.2.7.2 Maximum Tension Stress Criterion ............ 244 5.2.7.3 Distortion Energy Approach

  18. 33 CFR Appendix A to Part 154 - Guidelines for Detonation Flame Arresters

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CG-522). 1. Scope 1.1This standard provides the minimum requirements for design, construction.../Circ. 373/Rev. 1—Revised Standards for the Design, Testing and Locating of Devices to Prevent the... maximum design pressure drop for that maximum flow rate. 6.1.10Maximum operating pressure. 7. Materials 7...

  19. Numerical design and optimization of hydraulic resistance and wall shear stress inside pressure-driven microfluidic networks.

    PubMed

    Damiri, Hazem Salim; Bardaweel, Hamzeh Khalid

    2015-11-07

    Microfluidic networks represent the milestone of microfluidic devices. Recent advancements in microfluidic technologies mandate complex designs where both hydraulic resistance and pressure drop across the microfluidic network are minimized, while wall shear stress is precisely mapped throughout the network. In this work, a combination of theoretical and modeling techniques is used to construct a microfluidic network that operates under minimum hydraulic resistance and minimum pressure drop while constraining wall shear stress throughout the network. The results show that in order to minimize the hydraulic resistance and pressure drop throughout the network while maintaining constant wall shear stress throughout the network, geometric and shape conditions related to the compactness and aspect ratio of the parent and daughter branches must be followed. Also, results suggest that while a "local" minimum hydraulic resistance can be achieved for a geometry with an arbitrary aspect ratio, a "global" minimum hydraulic resistance occurs only when the aspect ratio of that geometry is set to unity. Thus, it is concluded that square and equilateral triangular cross-sectional area microfluidic networks have the least resistance compared to all rectangular and isosceles triangular cross-sectional microfluidic networks, respectively. Precise control over wall shear stress through the bifurcations of the microfluidic network is demonstrated in this work. Three multi-generation microfluidic network designs are considered. In these three designs, wall shear stress in the microfluidic network is successfully kept constant, increased in the daughter-branch direction, or decreased in the daughter-branch direction, respectively. For the multi-generation microfluidic network with constant wall shear stress, the design guidelines presented in this work result in identical profiles of wall shear stresses not only within a single generation but also through all the generations of the microfluidic network under investigation. The results obtained in this work are consistent with previously reported data and suitable for a wide range of lab-on-chip applications.

  20. Automated single cell sorting and deposition in submicroliter drops

    NASA Astrophysics Data System (ADS)

    Salánki, Rita; Gerecsei, Tamás; Orgovan, Norbert; Sándor, Noémi; Péter, Beatrix; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-08-01

    Automated manipulation and sorting of single cells are challenging, when intact cells are needed for further investigations, e.g., RNA or DNA sequencing. We applied a computer controlled micropipette on a microscope admitting 80 PCR (Polymerase Chain Reaction) tubes to be filled with single cells in a cycle. Due to the Laplace pressure, fluid starts to flow out from the micropipette only above a critical pressure preventing the precise control of drop volume in the submicroliter range. We found an anomalous pressure additive to the Laplace pressure that we attribute to the evaporation of the drop. We have overcome the problem of the critical dropping pressure with sequentially operated fast fluidic valves timed with a millisecond precision. Minimum drop volume was 0.4-0.7 μl with a sorting speed of 15-20 s per cell. After picking NE-4C neuroectodermal mouse stem cells and human primary monocytes from a standard plastic Petri dish we could gently deposit single cells inside tiny drops. 94 ± 3% and 54 ± 7% of the deposited drops contained single cells for NE-4C and monocytes, respectively. 7.5 ± 4% of the drops contained multiple cells in case of monocytes. Remaining drops were empty. Number of cells deposited in a drop could be documented by imaging the Petri dish before and after sorting. We tuned the adhesion force of cells to make the manipulation successful without the application of microstructures for trapping cells on the surface. We propose that our straightforward and flexible setup opens an avenue for single cell isolation, critically needed for the rapidly growing field of single cell biology.

  1. 40 CFR Table 3 to Subpart Hhh of... - Operating Parameters To Be Monitored and Minimum Measurement and Recording Frequencies

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... rural HMIWI HMIWI a with dry scrubber followed by fabric filter HMIWI a with wet scrubber HMIWI a with dry scrubber followed by fabric filter and wet scrubber Maximum operating parameters: Maximum charge... mercury (Hg) sorbent flow rate Hourly Once per hour ✔ ✔ Minimum pressure drop across the wet scrubber or...

  2. 40 CFR Table 3 to Subpart Ddddd of... - Operating Limits for Boilers and Process Heaters With Mercury Emission Limits and Boilers and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... minimum pressure drop and liquid flow-rate at or above the operating levels established during the... leak detection system alarm does not sound more than 5 percent of the operating time during a 6-month... control Maintain the minimum sorbent or carbon injection rate at or above the operating levels established...

  3. 40 CFR Table 3 to Subpart Ddddd of... - Operating Limits for Boilers and Process Heaters With Mercury Emission Limits and Boilers and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... minimum pressure drop and liquid flow-rate at or above the operating levels established during the... leak detection system alarm does not sound more than 5 percent of the operating time during a 6-month... control Maintain the minimum sorbent or carbon injection rate at or above the operating levels established...

  4. 40 CFR 63.9890 - What emission limitations must I meet?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... each emission limit in Table 1 to this subpart that applies to you. (b) For each wet scrubber applied... average pressure drop and scrubber liquid flow rate at or above the minimum level established during the...

  5. 40 CFR 63.9890 - What emission limitations must I meet?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... each emission limit in Table 1 to this subpart that applies to you. (b) For each wet scrubber applied... average pressure drop and scrubber liquid flow rate at or above the minimum level established during the...

  6. Multi-bottle, no compressor, mean pressure control system for a Stirling engine

    DOEpatents

    Corey, John A.

    1990-01-01

    The invention relates to an apparatus for mean pressure control of a Stirling engine without the need for a compressor. The invention includes a multi-tank system in which there is at least one high pressure level tank and one low pressure level tank wherein gas flows through a maximum pressure and supply line from the engine to the high pressure tank when a first valve is opened until the maximum pressure of the engine drops below that of the high pressure tank opening an inlet regulator to permit gas flow from the engine to the low pressure tank. When gas flows toward the engine it flows through the minimum pressure supply line 2 when a second valve is opened from the low pressure tank until the tank reaches the engine's minimum pressure level at which time the outlet regulator opens permitting gas to be supplied from the high pressure tank to the engine. Check valves between the two tanks prevent any backflow of gas from occurring.

  7. Computational fluid dynamics endpoints to characterize obstructive sleep apnea syndrome in children

    PubMed Central

    Luo, Haiyan; Persak, Steven C.; Sin, Sanghun; McDonough, Joseph M.; Isasi, Carmen R.; Arens, Raanan

    2013-01-01

    Computational fluid dynamics (CFD) analysis may quantify the severity of anatomical airway restriction in obstructive sleep apnea syndrome (OSAS) better than anatomical measurements alone. However, optimal CFD model endpoints to characterize or assess OSAS have not been determined. To model upper airway fluid dynamics using CFD and investigate the strength of correlation between various CFD endpoints, anatomical endpoints, and OSAS severity, in obese children with OSAS and controls. CFD models derived from magnetic resonance images were solved at subject-specific peak tidal inspiratory flow; pressure at the choanae was set by nasal resistance. Model endpoints included airway wall minimum pressure (Pmin), flow resistance in the pharynx (Rpharynx), and pressure drop from choanae to a minimum cross section where tonsils and adenoids constrict the pharynx (dPTAmax). Significance of endpoints was analyzed using paired comparisons (t-test or Wilcoxon signed rank test) and Spearman correlation. Fifteen subject pairs were analyzed. Rpharynx and dPTAmax were higher in OSAS than control and most significantly correlated to obstructive apnea-hypopnea index (oAHI), r = 0.48 and r = 0.49, respectively (P < 0.01). Airway minimum cross-sectional correlation to oAHI was weaker (r = −0.39); Pmin was not significantly correlated. CFD model endpoints based on pressure drops in the pharynx were more closely associated with the presence and severity of OSAS than pressures including nasal resistance, or anatomical endpoints. This study supports the usefulness of CFD to characterize anatomical restriction of the pharynx and as an additional tool to evaluate subjects with OSAS. PMID:24265282

  8. 40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... ETI °F ±.1°F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5°F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

  9. 40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

  10. 40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

  11. 40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

  12. 40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ETI °F ±.1 °F. Pressure depression upstream of LFE EPI “H20 ±.1“H20. Pressure drop across the LFE matrix EDP “H20 ±.005“H20. Air temperature at CVS pump inlet PTI °F ±.5 °F. Pressure depression at CVS... condition in an increment of pump inlet depression (about 4″ H2O) that will yield a minimum of six data...

  13. 40 CFR 63.1258 - Monitoring Requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... new operating scenario is implemented based on process knowledge and representative operating data... specified for control scenarios in Table 4 of this subpart and in paragraphs (b)(1)(ii) through (xi) of this.... The minimum scrubber flowrate or pressure drop shall be based on the conditions anticipated under...

  14. Pneumatic Conveying of Seed Cotton: Minimum Velocity and Pressure Drop

    USDA-ARS?s Scientific Manuscript database

    Electricity is major cost for cotton gins, representing approximately 20% of the industry’s variable costs. Fans used for pneumatic conveying consume the majority of electricity at cotton gins. Development of control systems to reduce the air velocity used for conveying seed cotton could significant...

  15. Pneumatic Conveying of Seed Cotton: Minimum Velocity and Pressure Drop

    USDA-ARS?s Scientific Manuscript database

    Electricity is a major cost for cotton gins, representing approximately 20% of variable costs. Fans used for pneumatic conveying consume the majority of electricity at cotton gins. Development of control systems to reduce the air velocity used for conveying seed cotton could significantly decrease e...

  16. 40 CFR 86.119-90 - CVS calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

  17. 40 CFR 86.119-90 - CVS calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

  18. 40 CFR 86.119-90 - CVS calibration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

  19. 40 CFR 86.119-90 - CVS calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

  20. 40 CFR 86.119-90 - CVS calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) Pressure depression upstream of LFE EPI in. H2O (kPa) ±0.05 in. H20 (±0.012 kPa) Pressure drop across the...) ±0.5 °F (±0.3 °C) Pressure depression at CVS pump inlet PPI in. fluid (kPa) ±0.05 in. fluid (±0.022 k... depression (about 4 in. H2O (1.0 kPa) that will yield a minimum of six data points for the total calibration...

  1. Simulated Altitude Investigation of Stewart-Warner Model 906-B Combustion Heater

    NASA Technical Reports Server (NTRS)

    Ebersbach, Frederick R.; Cervenka, Adolph J.

    1947-01-01

    An investigation has been conducted to determine thermal and pressure-drop performance and the operational characteristics of a Stewart-Warner model 906-B combustion heater. The performance tests covered a range of ventilating-air flows from 500 to 3185 pounds per hour, combustion-air pressure drops from 5 to 35 inches of water, and pressure altitudes from sea level to 41,000 feet. The operational characteristics investigated were the combustion-air flows for sustained combustion and for consistent ignition covering fuel-air ratios ranging from 0.033 to 0.10 and pressure altitudes from sea level to 45,000 feet. Rated heat output of 50,000 Btu per hour was obtained at pressure altitudes up to 27,000 feet for ventilating-air flows greater than 800 pounds per hour; rated output was not obtained at ventilating-air flow below 800 pounds per hour at any altitude. The maximum heater efficiency was found to be 60.7 percent at a fuel-air ratio of 0.050, a sea-level pressure altitude, a ventilating-air temperature of 0 F, combustion-air temperature of 14 F, a ventilating-air flow of 690 pounds per hour, and a combustion-air flow of 72.7 pounds per hour. The minimum combustion-air flow for sustained combustion at a pressure altitude of 25,000 feet was about 9 pounds per hour for fuel-air ratios between 0.037 and 0.099 and at a pressure altitude of 45,000 feet increased to 18 pounds per hour at a fuel-air ratio of 0.099 and 55 pounds per hour at a fuel-air ratio of 0.036. Combustion could be sustained at combustion-air flows above values of practical interest. The maximum flow was limited, however, by excessively high exhaust-gas temperature or high pressure drop. Both maximum and minimum combustion-air flows for consistent ignition decrease with increasing pressure altitude and the two curves intersect at a pressure altitude of approximately 25,000 feet and a combustion-air flow of approximately 28 pounds per hour.

  2. Study of cryogenic propellant systems for loading the space shuttle. Part 2: Hydrogen systems

    NASA Technical Reports Server (NTRS)

    Steward, W. G.

    1975-01-01

    Computer simulation studies of liquid hydrogen fill and vent systems for the space shuttle are studied. The computer programs calculate maximum and minimum permissible flow rates during cooldown as limited by thermal stress considerations, fill line cooldown time, pressure drop, flow rates, vapor content, vent line pressure drop and vent line discharge temperature. The input data for these programs are selected through graphic displays which schematically depict the part of the system being analyzed. The computed output is also displayed in the form of printed messages and graphs. Digital readouts of graph coordinates may also be obtained. Procedures are given for operation of the graphic display unit and the associated minicomputer and timesharing computer.

  3. 40 CFR Table 5 to Subpart Mmmmm of... - Continuous Compliance With Emission Limits and Operating Limits

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... performance test. v. If you use a venturi scrubber, maintaining the daily average pressure drop across the.... Each new or reconstructed flame lamination affected source using a scrubber a. Maintain the daily average scrubber inlet liquid flow rate above the minimum value established during the performanceb...

  4. 40 CFR 63.1366 - Monitoring and inspection requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... scenario is implemented based on process knowledge and representative operating data. The procedures used... control scenarios in paragraphs (b)(1)(ii) through (xii) of this section, and are summarized in Table 3 of... also be monitored once a day. The minimum scrubber liquid flow rate or pressure drop shall be based on...

  5. 40 CFR Table 2 to Subpart III of... - Operating Limits for Wet Scrubbers

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 8 2011-07-01 2011-07-01 false Operating Limits for Wet Scrubbers 2... Part 62—Operating Limits for Wet Scrubbers For these operating parameters You must establish these... and intermittent units) a Pressure drop across the wet scrubber or amperage to wet scrubber Minimum...

  6. 40 CFR Table 2 to Subpart III of... - Operating Limits for Wet Scrubbers

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Operating Limits for Wet Scrubbers 2... Part 62—Operating Limits for Wet Scrubbers For these operating parameters You must establish these... and intermittent units) a Pressure drop across the wet scrubber or amperage to wet scrubber Minimum...

  7. Engine Hydraulic Stability. [injector model for analyzing combustion instability

    NASA Technical Reports Server (NTRS)

    Kesselring, R. C.; Sprouse, K. M.

    1977-01-01

    An analytical injector model was developed specifically to analyze combustion instability coupling between the injector hydraulics and the combustion process. This digital computer dynamic injector model will, for any imposed chamber of inlet pressure profile with a frequency ranging from 100 to 3000 Hz (minimum) accurately predict/calculate the instantaneous injector flowrates. The injector system is described in terms of which flow segments enter and leave each pressure node. For each flow segment, a resistance, line lengths, and areas are required as inputs (the line lengths and areas are used in determining inertance). For each pressure node, volume and acoustic velocity are required as inputs (volume and acoustic velocity determine capacitance). The geometric criteria for determining inertances of flow segments and capacitance of pressure nodes was set. Also, a technique was developed for analytically determining time averaged steady-state pressure drops and flowrates for every flow segment in an injector when such data is not known. These pressure drops and flowrates are then used in determining the linearized flow resistance for each line segment of flow.

  8. Investigating the effects of rock porosity and permeability on the performance of nitrogen injection into a southern Iranian oil reservoirs through neural network

    NASA Astrophysics Data System (ADS)

    Gheshmi, M. S.; Fatahiyan, S. M.; Khanesary, N. T.; Sia, C. W.; Momeni, M. S.

    2018-03-01

    In this work, a comprehensive model for Nitrogen injection into an oil reservoir (southern Iranian oil fields) was developed and used to investigate the effects of rock porosity and permeability on the oil production rate and the reservoir pressure decline. The model was simulated and developed by using ECLIPSE300 software, which involved two scenarios as porosity change and permeability changes in the horizontal direction. We found that the maximum pressure loss occurs at a porosity value of 0.07, which later on, goes to pressure buildup due to reservoir saturation with the gas. Also we found that minimum pressure loss is encountered at porosity 0.46. Increases in both pressure and permeability in the horizontal direction result in corresponding increase in the production rate, and the pressure drop speeds up at the beginning of production as it increases. However, afterwards, this pressure drop results in an increase in pressure because of reservoir saturation. Besides, we determined the regression values, R, for the correlation between pressure and total production, as well as for the correlation between permeability and the total production, using neural network discipline.

  9. 40 CFR Table 2 to Subpart Mmmmm of... - Operating Limits for New or Reconstructed Flame Lamination Affected Sources

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... scrubber, maintain the daily average pressure drop across the venturi within the operating range value... . . . You must . . . 1. Scrubber a. Maintain the daily average scrubber inlet liquid flow rate above the minimum value established during the performance test. b. Maintain the daily average scrubber effluent pH...

  10. 40 CFR Table 2 to Subpart Mmmmm of... - Operating Limits for New or Reconstructed Flame Lamination Affected Sources

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... . . . You must . . . 1. Scrubber a. Maintain the daily average scrubber inlet liquid flow rate above the minimum value established during the performance test. b. Maintain the daily average scrubber effluent pH... scrubber, maintain the daily average pressure drop across the venturi within the operating range value...

  11. Comments on settling chamber design for quiet, blowdown wind tunnels

    NASA Technical Reports Server (NTRS)

    Beckwith, I. E.

    1981-01-01

    Transfer of an existing continous circuit supersonic wind tunnel to Langley and its operation there as a blowdown tunnel is planned. Flow disturbance requirements in the supply section and methods for reducing the high level broad band acoustic disturbances present in typical blowdown tunnels are reviewed. Based on recent data and the analysis of two blowdown facilities at Langley, methods for reducing the total turbulence levels in the settling chamber, including both acoustic and vorticity modes, to less than one percent are recommended. The pertinent design details of the damping screens and honeycomb and the recommended minimum pressure drop across the porous components providing the required two orders of magnitude attenuation of acoustic noise levels are given. A suggestion for the support structure of these high pressure drop porous components is offered.

  12. 25 CFR 543.17 - What are the minimum internal control standards for drop and count?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 2 2013-04-01 2013-04-01 false What are the minimum internal control standards for drop and count? 543.17 Section 543.17 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR HUMAN SERVICES MINIMUM INTERNAL CONTROL STANDARDS FOR CLASS II GAMING § 543.17 What are the minimum internal control standards for drop and count?...

  13. 25 CFR 543.17 - What are the minimum internal control standards for drop and count?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 2 2014-04-01 2014-04-01 false What are the minimum internal control standards for drop and count? 543.17 Section 543.17 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR HUMAN SERVICES MINIMUM INTERNAL CONTROL STANDARDS FOR CLASS II GAMING § 543.17 What are the minimum internal control standards for drop and count?...

  14. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations

    PubMed Central

    Tricomi, Leonardo; Melchiori, Tommaso; Chiaramonti, David; Boulet, Micaël; Lavoie, Jean Michel

    2017-01-01

    Based upon the two fluid model (TFM) theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD) distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD) was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law), restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal’s energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum. PMID:28695119

  15. Sensitivity Analysis and Accuracy of a CFD-TFM Approach to Bubbling Bed Using Pressure Drop Fluctuations.

    PubMed

    Tricomi, Leonardo; Melchiori, Tommaso; Chiaramonti, David; Boulet, Micaël; Lavoie, Jean Michel

    2017-01-01

    Based upon the two fluid model (TFM) theory, a CFD model was implemented to investigate a cold multiphase-fluidized bubbling bed reactor. The key variable used to characterize the fluid dynamic of the experimental system, and compare it to model predictions, was the time-pressure drop induced by the bubble motion across the bed. This time signal was then processed to obtain the power spectral density (PSD) distribution of pressure fluctuations. As an important aspect of this work, the effect of the sampling time scale on the empirical power spectral density (PSD) was investigated. A time scale of 40 s was found to be a good compromise ensuring both simulation performance and numerical validation consistency. The CFD model was first numerically verified by mesh refinement process, after what it was used to investigate the sensitivity with regards to minimum fluidization velocity (as a calibration point for drag law), restitution coefficient, and solid pressure term while assessing his accuracy in matching the empirical PSD. The 2D model provided a fair match with the empirical time-averaged pressure drop, the relating fluctuations amplitude, and the signal's energy computed as integral of the PSD. A 3D version of the TFM was also used and it improved the match with the empirical PSD in the very first part of the frequency spectrum.

  16. Flow of High Internal Phase Ratio Emulsions through Pipes

    NASA Astrophysics Data System (ADS)

    Kostak, K.; Özsaygı, R.; Gündüz, I.; Yorgancıoǧlu, E.; Tekden, E.; Güzel, O.; Sadıklar, D.; Peker, S.; Helvacı, Ş. Ş.

    2015-04-01

    The flow behavior of W/O type of HIPRE stabilized by hydrogen bonds with a sugar (sorbitol) in the aqueous phase, was studied. Two groups of experiments were done in this work: The effect of wall shear stresses were investigated in flow through pipes of different diameters. For this end, HIPREs prestirred at constant rate for the same duration were used to obtain similar drop size distributions. Existence and extent of elongational viscosity were used as a probe to elucidate the effect of drop size distribution on the flow behavior: HIPREs prestirred for the same duration at different rates were subjected to flow through converging pipes. The experimental flow curves for flow through small cylindrical pipes indicated four different stages: 1) initial increase in the flow rate at low pressure difference, 2) subsequent decrease in the flow rate due to capillary flow, 3) pressure increase after reaching the minimum flow rate and 4) slip flow after a critical pressure difference. HIPREs with sufficient external liquid phase in the plateau borders can elongate during passage through converging pipes. In the absence of liquid stored in the plateau borders, the drops rupture during extension and slip flow takes place without elongation.

  17. The effect of catalyst length and downstream reactor distance on catalytic combustor performance

    NASA Technical Reports Server (NTRS)

    Anderson, D.

    1980-01-01

    A study was made to determine the effects on catalytic combustor performance which resulted from independently varying the length of a catalytic reactor and the length available for gas-phase reactions downstream of the catalyst. Monolithic combustion catalysts from three manufacturers were tested in a combustion test rig with no. 2 diesel fuel. Catalytic reactor lengths of 2.5 and 5.4 cm, and downstream gas-phase reaction distances of 7.3, 12.4, 17.5, and 22.5 cm were evaluated. Measurements of carbon monoxide, unburned hydrocarbons, nitrogen oxides, and pressure drop were made. The catalytic-reactor pressure drop was less than 1 percent of the upstream total pressure for all test configurations and test conditions. Nitrogen oxides and unburned hydrocarbons emissions were less than 0.25 g NO2/kg fuel and 0.6 g HC/kg fuel, respectively. The minimum operating temperature (defined as the adiabatic combustion temperature required to obtain carbon monoxide emissions below a reference level of 13.6 g CO/kg fuel) ranged from 1230 K to 1500 K for the various conditions and configurations tested. The minimum operating temperature decreased with increasing total (catalytic-reactor-plus-downstream-gas-phase-reactor-zone) residence time but was independent of the relative times spent in each region when the catalytic-reactor residence time was greater than or equal to 1.4 ms.

  18. Evaluation of minimum quantity lubrication grinding with nano-particles and recent related patents.

    PubMed

    Li, Changhe; Wang, Sheng; Zhang, Qiang; Jia, Dongzhou

    2013-06-01

    In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a supply system for the grinding fluid in nano-particle jet MQL, which produced MQL lubricant by adding solid nano-particles in degradable grinding fluid. The MQL supply device turns the lubricant to the pulse drops with fixed pressure, unchanged pulse frequency and the same drop diameter. The drops will be produced and injected in the grinding zone in the form of jet flow under high pressure gas and air seal. As people become increasingly demanding on our environment, minimum quantity lubrication has been widely used in the grinding and processing. Yet, it presents the defect of insufficient cooling performance, which confines its development. To improve the heat transfer efficiency of MQL, nano-particles of a certain mass fraction can be added in the minimum quantity of lubricant oil, which concomitantly will improve the lubrication effects in the processing. In this study, the grinding experiment corroborated the effect of nano-particles in surface grinding. In addition, compared with other forms of lubrication, the results presented that the grinding force, the friction coefficient and specific grinding energy of MQL grinding have been significantly weakened, while G ratio greatly rose. These are attributed to the friction oil-film with excellent anti-friction and anti-wear performance, which is generated nano-particles at the wheel/workpiece interface. In this research, the cooling performance of nano-particle jet MQL was analyzed. Based on tests and experiments, the surface temperature was assayed from different methods, including flood lubricating oil, dry grinding, MQL grinding and nano-particle jet MQL grinding. Because of the outstanding heat transfer performance of nano-particles, the ratio of heat delivered by grinding media was increased, leading to lower temperature in the grinding zone. Results demonstrate that nano-particle jet MQL has satisfactory cooling performance as well as a promising future of extensive application.

  19. Artificial neural network modeling of a deflector in a grooved channel as well as optimization of its effective parameters

    NASA Astrophysics Data System (ADS)

    Abdollahi, Azita; Shams, Mehrzad; Abdollahi, Anita

    2018-01-01

    One of methods available to increase the rate of heat transfer in channels with parallel plates is making grooves in them. But, the fundamental problem of this method is the formation of stagnation zone in the grooves and as a result formation a zone with low energy transfer. In this paper, the effect of placing curved deflectors (geometries with elliptical forms) in channel on thermal and hydraulic characteristic of the fluid flow- with the aim of directing of the flow into the grooves and as a result increasing the rate of heat transfer in this zone- are investigated and heat transfer coefficient and pressure drop are calculated for different values of Reynolds number and geometrical parameters of the deflector (its small and large radiuses). The results show that the presence of the deflector in the channel significantly increases the heat transfer rate compare to the channel without deflector. Of course, it should be noted that this work also increases the pressure drop. So, finally in order to determine configurations of the deflector causing minimum pressure drop, maximum Nusselt number or a balance between them, optimization algorithm consisting of artificial neural network and multi-objective genetic algorithm was utilized to calculate the optimal values of these parameters.

  20. Hydrophobic properties of a wavy rough substrate.

    PubMed

    Carbone, G; Mangialardi, L

    2005-01-01

    The wetting/non-wetting properties of a liquid drop in contact with a chemically hydrophobic rough surface (thermodynamic contact angle theta(e)>pi/2) are studied for the case of an extremely idealized rough profile: the liquid drop is considered to lie on a simple sinusoidal profile. Depending on surface geometry and pressure values, it is found that the Cassie and Wenzel states can coexist. But if the amplitude h of the substrate is sufficiently large the only possible stable state is the Cassie one, whereas if h is below a certain critical value hcr a transition to the Wenzel state occurs. Since in many potential applications of such super-hydrophobic surfaces, liquid drops often collide with the substrate (e.g. vehicle windscreens), in the paper the critical drop pressure pW is calculated at which the Cassie state is no longer stable and the liquid jumps into full contact with the substrate (Wenzel state). By analyzing the asymptotic behavior of the systems in the limiting case of a large substrate corrugation, a simple criterion is also proposed to calculate the minimum height asperity h necessary to prevent the Wenzel state from being formed, to preserve the super-hydrophobic properties of the substrate, and, hence, to design a robust super-hydrophobic surface.

  1. Process for heating coal-oil slurries

    DOEpatents

    Braunlin, W.A.; Gorski, A.; Jaehnig, L.J.; Moskal, C.J.; Naylor, J.D.; Parimi, K.; Ward, J.V.

    1984-01-03

    Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec[sup [minus]1]. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72. 29 figs.

  2. Process for heating coal-oil slurries

    DOEpatents

    Braunlin, Walter A.; Gorski, Alan; Jaehnig, Leo J.; Moskal, Clifford J.; Naylor, Joseph D.; Parimi, Krishnia; Ward, John V.

    1984-01-03

    Controlling gas to slurry volume ratio to achieve a gas holdup of about 0.4 when heating a flowing coal-oil slurry and a hydrogen containing gas stream allows operation with virtually any coal to solvent ratio and permits operation with efficient heat transfer and satisfactory pressure drops. The critical minimum gas flow rate for any given coal-oil slurry will depend on numerous factors such as coal concentration, coal particle size distribution, composition of the solvent (including recycle slurries), and type of coal. Further system efficiency can be achieved by operating with multiple heating zones to provide a high heat flux when the apparent viscosity of the gas saturated slurry is highest. Operation with gas flow rates below the critical minimum results in system instability indicated by temperature excursions in the fluid and at the tube wall, by a rapid increase and then decrease in overall pressure drop with decreasing gas flow rate, and by increased temperature differences between the temperature of the bulk fluid and the tube wall. At the temperatures and pressures used in coal liquefaction preheaters the coal-oil slurry and hydrogen containing gas stream behaves essentially as a Newtonian fluid at shear rates in excess of 150 sec.sup. -1. The gas to slurry volume ratio should also be controlled to assure that the flow regime does not shift from homogeneous flow to non-homogeneous flow. Stable operations have been observed with a maximum gas holdup as high as 0.72.

  3. On pressure measurement and seasonal pressure variations during the Phoenix mission

    NASA Astrophysics Data System (ADS)

    Taylor, Peter A.; Kahanpää, Henrik; Weng, Wensong; Akingunola, Ayodeji; Cook, Clive; Daly, Mike; Dickinson, Cameron; Harri, Ari-Matti; Hill, Darren; Hipkin, Victoria; Polkko, Jouni; Whiteway, Jim

    2010-03-01

    In situ surface pressures measured at 2 s intervals during the 150 sol Phoenix mission are presented and seasonal variations discussed. The lightweight Barocap®/Thermocap® pressure sensor system performed moderately well. However, the original data processing routine had problems because the thermal environment of the sensor was subject to more rapid variations than had been expected. Hence, the data processing routine was updated after Phoenix landed. Further evaluation and the development of a correction are needed since the temperature dependences of the Barocap sensor heads have drifted after the calibration of the sensor. The inaccuracy caused by this appears when the temperature of the unit rises above 0°C. This frequently affects data in the afternoons and precludes a full study of diurnal pressure variations at this time. Short-term fluctuations, on time scales of order 20 s are unaffected and are reported in a separate paper in this issue. Seasonal variations are not significantly affected by this problem and show general agreement with previous measurements from Mars. During the 151 sol mission the surface pressure dropped from around 860 Pa to a minimum (daily average) of 724 Pa on sol 140 (Ls 143). This local minimum occurred several sols earlier than expected based on GCM studies and Viking data. Since battery power was lost on sol 151 we are not sure if the timing of the minimum that we saw could have been advanced by a low-pressure meteorological event. On sol 95 (Ls 122), we also saw a relatively low-pressure feature. This was accompanied by a large number of vertical vortex events, characterized by short, localized (in time), low-pressure perturbations.

  4. Mixed Refrigerants for a Glass Capillary Micro Cryogenic Cooler

    DTIC Science & Technology

    2010-08-01

    refrigerant has the largest ðDhTÞmin 1.35 kJ/mol. To deliver 15 mW of gross refrigeration power, JT cryocoolers using mixed refrigerants only require 1.6...higher than 75 K. Pressure drop in heat exchangers can cause refrigeration loss in cryocooler systems. The minimum enthalpy difference and hence...micro- cryocoolers . They solved it by making the returning flow laminar through re-design- ing micro channels. Fig. 4 shows the relationship between the

  5. Pressure, temperature and density drops along supercritical fluid chromatography columns. I. Experimental results for neat carbon dioxide and columns packed with 3- and 5-micron particles.

    PubMed

    Poe, Donald P; Veit, Devon; Ranger, Megan; Kaczmarski, Krzysztof; Tarafder, Abhijit; Guiochon, Georges

    2012-08-10

    The pressure drop and temperature drop on columns packed with 3- and 5-micron particles were measured using neat CO(2) at a flow rate of 5 mL/min, at temperatures from 20°C to 100°C, and outlet pressures from 80 to 300 bar. The density drop was calculated based on the temperature and pressure at the column inlet and outlet. The columns were suspended in a circulating air bath either bare or covered with foam insulation. The results show that the pressure drop depends on the outlet pressure, the operating temperature, and the thermal environment. A temperature drop was observed for all conditions studied. The temperature drop was relatively small (less than 3°C) for combinations of low temperature and high pressure. Larger temperature drops and density drops occurred at higher temperatures and low to moderate pressures. Covering the column with thermal insulation resulted in larger temperature drops and corresponding smaller density drops. At 20°C the temperature drop was never more than a few degrees. The largest temperature drops occurred for both columns when insulated at 80°C and 80 bar, reaching a maximum value of 21°C for the 5-micron column, and 26°C for the 3-micron column. For an adiabatic column, the temperature drop depends on the pressure drop, the thermal expansion coefficient, and the density and the heat capacity of the mobile phase fluid, and can be described by a simple mathematical relationship. For a fixed operating temperature and outlet pressure, the temperature drop increases monotonically with the pressure drop. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Membrane-Based Gas Traps for Ammonia, Freon-21, and Water Systems to Simplify Ground Processing

    NASA Technical Reports Server (NTRS)

    Ritchie, Stephen M. C.

    2003-01-01

    Gas traps are critical for the smooth operation of coolant loops because gas bubbles can cause loss of centrifugal pump prime, interference with sensor readings, inhibition of heat transfer, and blockage of passages to remote systems. Coolant loops are ubiquitous in space flight hardware, and thus there is a great need for this technology. Conventional gas traps will not function in micro-gravity due to the absence of buoyancy forces. Therefore, clever designs that make use of adhesion and momentum are required for adequate separation, preferable in a single pass. The gas traps currently used in water coolant loops on the International Space Station are composed of membrane tube sets in a shell. Each tube set is composed of a hydrophilic membrane (used for water transport and capture of bubbles) and a hydrophobic membrane (used for venting of air bubbles). For the hydrophilic membrane, there are two critical pressures, the pressure drop and the bubble pressure. The pressure drop is the decrease in system pressure across the gas trap. The bubble pressure is the pressure required for air bubbles to pass across the water filled membrane. A significant difference between these pressures is needed to ensure complete capture of air bubbles in a single pass. Bubbles trapped by the device adsorb on the hydrophobic membrane in the interior of the hydrophilic membrane tube. After adsorption, the air is vented due to a pressure drop of approximately 1 atmosphere across the membrane. For water systems, the air is vented to the ambient (cabin). Because water vapor can also transport across the hydrophobic membrane, it is critical that a minimum surface area is used to avoid excessive water loss (would like to have a closed loop for the coolant). The currently used gas traps only provide a difference in pressure drop and bubble pressure of 3-4 psid. This makes the gas traps susceptible to failure at high bubble loading and if gas venting is impaired. One mechanism for the latter is when particles adhere to the hydrophobic membrane, promoting formation of a water layer about it that can blind the membrane for gas transport (Figure 1). This mechanism is the most probable cause for observed failures with the existing design. The objective of this project was to devise a strategy for choosing new membrane materials (database development and procedure), redesign of the gas trap to mitigate blinding effects, and to develop a design that can be used in ammonia and Freon-21 coolant loops.

  7. Experimental Investigation of Oscillatory Flow Pressure and Pressure Drop Through Complex Geometries

    NASA Technical Reports Server (NTRS)

    Ibrahim, Mounir B.; Wang, Meng; Gedeon, David

    2005-01-01

    A series of experiments have been performed to investigate the oscillatory flow pressure and pressure drop through complex geometries. These experiments were conducted at the CSU-SLRE facility which is a horizontally opposed, two-piston, single-acting engine with a split crankshaft driving mechanism. Flow through a rectangular duct, with no insert (obstruction), was studied first. Then four different inserts were examined: Abrupt, Manifold, Diverging Short and Diverging Long. The inserts were mounted in the center of the rectangular duct to represent different type of geometries that could be encountered in Stirling machines. The pressure and pressure drop of the oscillating flow was studied for: 1) different inserts, 2) different phase angle between the two pistons of the engine (zero, 90 lead, 180, and 90 lag), and 3) for different piston frequencies (5, 10, 15, and 20 Hz). It was found that the pressure drop of the oscillatory flow increases with increasing Reynolds number. The pressure drop was shown to be mainly due to the gas inertia for the case of oscillatory flow through a rectangular duct with no insert. On the other hand, for the cases with different inserts into the rectangular duct, the pressure drop has three sources: inertia, friction, and local losses. The friction pressure drop is only a small fraction of the total pressure drop. It was also shown that the dimensionless pressure drop decreases with increasing kinetic Reynolds number.

  8. An optimized microstructure to minimizing in-plane and through-plane pressure drops of fibrous materials: Counter-intuitive reduction of gas diffusion layer permeability with porosity

    NASA Astrophysics Data System (ADS)

    Sadeghifar, Hamidreza

    2018-05-01

    The present study experimentally investigates the realistic functionality of in-plane and through-plane pressure drops of layered fibrous media with porosity, fiber diameter, fiber spacing, fiber-fiber angles and fiber-flow angles. The study also reveals that pressure drop may increase with porosity and fiber diameter under specific circumstances. This counter-intuitive point narrows down the validity range of widely-used permeability-porosity-diameter models or correlations. It is found that, for fibrous materials, the most important parameter that impacts the in-plane pressure drop is not their porosities but the number of fibers extended in the flow direction. It is also concluded that in-plane pressure drop is highly dependent upon the flow direction (fiber-flow angles), especially at lower porosities. Contrary to in-plane pressure drop, through-plane pressure drop is a weak function of fiber-fiber angles but is strongly impacted by fiber spacing, especially at lower porosities. At a given porosity, low through-plane pressure drops occur if fiber spacing does not change practically from one layer to another. Through-plane pressure drop also, insignificantly, increases with the intersecting angles between fibers. An optimized microstructure of fibrous media resulting in minimal in-plane and through-plane pressure drops is also offered for the first time in this work.

  9. A fluid--structure interaction finite element analysis of pulsatile blood flow through a compliant stenotic artery

    NASA Technical Reports Server (NTRS)

    Bathe, M.; Kamm, R. D.

    1999-01-01

    A new model is used to analyze the fully coupled problem of pulsatile blood flow through a compliant, axisymmetric stenotic artery using the finite element method. The model uses large displacement and large strain theory for the solid, and the full Navier-Stokes equations for the fluid. The effect of increasing area reduction on fluid dynamic and structural stresses is presented. Results show that pressure drop, peak wall shear stress, and maximum principal stress in the lesion all increase dramatically as the area reduction in the stenosis is increased from 51 to 89 percent. Further reductions in stenosis cross-sectional area, however, produce relatively little additional change in these parameters due to a concomitant reduction in flow rate caused by the losses in the constriction. Inner wall hoop stretch amplitude just distal to the stenosis also increases with increasing stenosis severity, as downstream pressures are reduced to a physiological minimum. The contraction of the artery distal to the stenosis generates a significant compressive stress on the downstream shoulder of the lesion. Dynamic narrowing of the stenosis is also seen, further augmenting area constriction at times of peak flow. Pressure drop results are found to compare well to an experimentally based theoretical curve, despite the assumption of laminar flow.

  10. 40 CFR Table 5 to Subpart Jjjjj of... - Continuous Compliance With Emission Limits and Operating Limits

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... kilns equipped with WS i. Collecting the scrubber pressure drop data according to § 63.8450(a); reducing the scrubber pressure drop data to 3-hour block averages according to § 63.8450(a); maintaining the average scrubber pressure drop for each 3-hour block period at or above the average pressure drop...

  11. Effects of phosphoric acid sprayed into an incinerator furnace on the flue gas pressure drop at fabric filters.

    PubMed

    Takahashi, Shigetoshi; Hwang, In-Hee; Matsuto, Toshihiko

    2016-06-01

    Fabric filters are widely used to remove dust from flue gas generated by waste incineration. However, a pressure drop occurs at the filters, caused by growth of a dust layer on the filter fabric despite regular cleaning by pulsed-jet air. The pressure drop at the fabric filters leads to energy consumption at induced draft fan to keep the incinerator on negative pressure, so that its proper control is important to operate incineration facility efficiently. The pressure drop at fabric filters decreased whenever phosphoric acid wastewater (PAW) was sprayed into an incinerator for treating industrial waste. Operational data obtained from the incineration facility were analyzed to determine the short- and long-term effects of PAW spraying on the pressure drop. For the short-term effect, it was confirmed that the pressure drop at the fabric filters always decreased to 0.3-1.2kPa within about 5h after spraying PAW. This effect was expected to be obtained by about one third of present PAW spraying amount. However, from the long-term perspective, the pressure drop showed an increase in the periods of PAW spraying compared with periods for which PAW spraying was not performed. The pressure drop increase was particularly noticeable after the initial PAW spraying, regardless of the age and type of fabric filters used. These results suggest that present PAW spraying causes a temporary pressure drop reduction, leading to short-term energy consumption savings; however, it also causes an increase of the pressure drop over the long-term, degrading the overall operating conditions. Thus, appropriate PAW spraying conditions are needed to make effective use of PAW to reduce the pressure drop at fabric filters from a short- and long-term point of view. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Experimental investigations of stability of static liquid fillets and liquid-gas interface in capillary passages for gas-free liquid acquisition in zero gravity

    NASA Astrophysics Data System (ADS)

    Purohit, Ghanshyam Purshottamdas

    Experimental investigations of static liquid fillets formed between small gaps of a cylindrical surface and a flat surface are carried out. The minimum volume of liquid required to form a stable fillet and the maximum liquid content the fillet can hold before becoming unstable are studied. Fillet shapes are captured in photographs obtained by a high speed image system. Experiments were conducted using water, UPA and PF 5060 on two surfaces-stand-blasted titanium and polished copper for different surface inclinations. Experimental data are generalized using appropriate non-dimensional groups. Analytical model are developed to describe the fillet curvature. Fillet curvature data are compared against model predictions and are found to be in close agreement. Bubble point experiments were carried out to measure the capillary pressure difference across the liquid-gas interface in the channels of photo-chemically etched disk stacks. Experiments were conducted using titanium stacks of five different geometrical configurations. Both well wetting liquids (IPA and PF5060) and partially wetting liquid (water) were used during experiments. Test results are found to be in close agreement with analytical predictions. Experiments were carried out to measure the frictional pressure drop across the stack as a function of liquid flow rate using two different liquids (water and IPA) and five stacks of different geometrical configurations. A channel pressure drop model is developed by treating the flow within stack channels as fully developed laminar flow between parallel plates and solving the one-dimensional Navier Stokes equation. An alternate model is developed by treating the flow in channels as flow within porous media. Expressions are developed for effective porosity and permeability for the stacks and the pressure drop is related to these parameters. Pressure drop test results are found to be in close agreement with model predictions. As a specific application of this work, a surface tension propellant management device (PMD) that uses photo-chemically etched disk stacks as capillary elements is examined. These PMDs are used in gas pressurized liquid propellant tanks to supply gas-free propellant to rocket engines in near zero-gravity environment. The experimentally validated models are integrated to perform key analyses for predicting PMD performance in zero gravity.

  13. Correction of Pressure Drop in Steam and Water System in Performance Test of Boiler

    NASA Astrophysics Data System (ADS)

    Liu, Jinglong; Zhao, Xianqiao; Hou, Fanjun; Wu, Xiaowu; Wang, Feng; Hu, Zhihong; Yang, Xinsen

    2018-01-01

    Steam and water pressure drop is one of the most important characteristics in the boiler performance test. As the measuring points are not in the guaranteed position and the test condition fluctuation exsits, the pressure drop test of steam and water system has the deviation of measuring point position and the deviation of test running parameter. In order to get accurate pressure drop of steam and water system, the corresponding correction should be carried out. This paper introduces the correction method of steam and water pressure drop in boiler performance test.

  14. COMPARISON OF PRESSURE DROP PRODUCED BY SPIRAL WRAPS, COOKIE CUTTERS AND OTHER ROD BUNDLE SPACERS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Noyes, R.C.

    The problem of predicting pressure drop due to various fuel bundle spacers is considered in some detail. Three sets of experimental data are reviewed and presented in reduced form. These data are compared to several semitheoretical approaches to pressure drop prediction and a best method is selected to make the required predictions. The comparison between predictions for the ASCR spiral wrap spacer and cookie cutter spacer shows that both types of spacers produce about the same pressure drop. Spacer pressure drop is shown to be strongly dependent on spacer frontal area and pitch. (auth)

  15. Experimental investigation of the effect of air velocity on a unit cooler under frosting condition: a case study

    NASA Astrophysics Data System (ADS)

    Bayrak, Ergin; Çağlayan, Akın; Konukman, Alp Er S.

    2017-10-01

    Finned tube evaporators are used in a wide range of applications such as commercial and industrial cold/freezed storage rooms with high traffic loading under frosting conditions. In this case study, an evaporator with an integrated fan was manufactured and tested under frosting conditions by only changing the air flow rate in an ambient balanced type test laboratory compared to testing in a wind tunnel with a more uniform flow distribution in order to detect the effect of air flow rate on frosting. During the test, operation was performed separately based on three different air flow rates. The parameters concerning test operation such as the changes of air temperature, air relative humidity, surface temperature, air-side pressure drop and refrigerant side capacity etc. were followed in detail for each air flow rate. At the same time, digital images were captured in front of the evaporator; thus, frost thicknesses and blockage ratios at the course of fan stall were determined by using an image-processing technique. Consequently, the test and visual results showed that the trendline of air-side pressure drop increased slowly at the first stage of test operations, then increased linearly up to a top point and then the linearity was disrupted instantly. This point speculated the beginning of defrost operation for each case. In addition, despite detecting a velocity that needs to be avoided, a test applied at minimum air velocity is superior to providing minimum capacity in terms of loss of capacity during test operations.

  16. Gas Pressure-Drop Experiment

    ERIC Educational Resources Information Center

    Luyben, William L.; Tuzla, Kemal

    2010-01-01

    Most chemical engineering undergraduate laboratories have fluid mechanics experiments in which pressure drops through pipes are measured over a range of Reynolds numbers. The standard fluid is liquid water, which is essentially incompressible. Since density is constant, pressure drop does not depend on the pressure in the pipe. In addition, flow…

  17. 25 CFR 542.19 - What are the minimum internal control standards for accounting?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...; (3) Individual and statistical game records to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop by each table game, and to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop for each type of table game, by...

  18. 25 CFR 542.19 - What are the minimum internal control standards for accounting?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...; (3) Individual and statistical game records to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop by each table game, and to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop for each type of table game, by...

  19. 25 CFR 542.19 - What are the minimum internal control standards for accounting?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...; (3) Individual and statistical game records to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop by each table game, and to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop for each type of table game, by...

  20. 25 CFR 542.19 - What are the minimum internal control standards for accounting?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...; (3) Individual and statistical game records to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop by each table game, and to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop for each type of table game, by...

  1. 25 CFR 542.19 - What are the minimum internal control standards for accounting?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...; (3) Individual and statistical game records to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop by each table game, and to reflect statistical drop, statistical win, and the percentage of statistical win to statistical drop for each type of table game, by...

  2. 25 CFR 542.21 - What are the minimum internal control standards for drop and count for Tier A gaming operations?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... locked table game drop boxes shall be removed from the tables by a person independent of the pit shift... boxes shall be performed by a minimum of two persons, at least one of whom is independent of the pit... count team shall be independent of transactions being reviewed and counted. The count team shall be...

  3. 25 CFR 542.41 - What are the minimum internal control standards for drop and count for Tier C gaming operations?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... locked table game drop boxes shall be removed from the tables by a person independent of the pit shift... boxes shall be performed by a minimum of two persons, at least one of whom is independent of the pit.... (4) The count team shall be independent of transactions being reviewed and counted. The count team...

  4. Estimating the irreversible pressure drop across a stenosis by quantifying turbulence production using 4D Flow MRI

    PubMed Central

    Ha, Hojin; Lantz, Jonas; Ziegler, Magnus; Casas, Belen; Karlsson, Matts; Dyverfeldt, Petter; Ebbers, Tino

    2017-01-01

    The pressure drop across a stenotic vessel is an important parameter in medicine, providing a commonly used and intuitive metric for evaluating the severity of the stenosis. However, non-invasive estimation of the pressure drop under pathological conditions has remained difficult. This study demonstrates a novel method to quantify the irreversible pressure drop across a stenosis using 4D Flow MRI by calculating the total turbulence production of the flow. Simulation MRI acquisitions showed that the energy lost to turbulence production can be accurately quantified with 4D Flow MRI within a range of practical spatial resolutions (1–3 mm; regression slope = 0.91, R2 = 0.96). The quantification of the turbulence production was not substantially influenced by the signal-to-noise ratio (SNR), resulting in less than 2% mean bias at SNR > 10. Pressure drop estimation based on turbulence production robustly predicted the irreversible pressure drop, regardless of the stenosis severity and post-stenosis dilatation (regression slope = 0.956, R2 = 0.96). In vitro validation of the technique in a 75% stenosis channel confirmed that pressure drop prediction based on the turbulence production agreed with the measured pressure drop (regression slope = 1.15, R2 = 0.999, Bland-Altman agreement = 0.75 ± 3.93 mmHg). PMID:28425452

  5. Fluidization quality analyzer for fluidized beds

    DOEpatents

    Daw, C. Stuart; Hawk, James A.

    1995-01-01

    A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence.

  6. Fluidization quality analyzer for fluidized beds

    DOEpatents

    Daw, C.S.; Hawk, J.A.

    1995-07-25

    A control loop and fluidization quality analyzer for a fluidized bed utilizes time varying pressure drop measurements. A fast-response pressure transducer measures the overall bed pressure drop, or over some segment of the bed, and the pressure drop signal is processed to produce an output voltage which changes with the degree of fluidization turbulence. 9 figs.

  7. Atomistic modeling of dropwise condensation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sikarwar, B. S., E-mail: bssikarwar@amity.edu; Singh, P. L.; Muralidhar, K.

    The basic aim of the atomistic modeling of condensation of water is to determine the size of the stable cluster and connect phenomena occurring at atomic scale to the macroscale. In this paper, a population balance model is described in terms of the rate equations to obtain the number density distribution of the resulting clusters. The residence time is taken to be large enough so that sufficient time is available for all the adatoms existing in vapor-phase to loose their latent heat and get condensed. The simulation assumes clusters of a given size to be formed from clusters of smallermore » sizes, but not by the disintegration of the larger clusters. The largest stable cluster size in the number density distribution is taken to be representative of the minimum drop radius formed in a dropwise condensation process. A numerical confirmation of this result against predictions based on a thermodynamic model has been obtained. Results show that the number density distribution is sensitive to the surface diffusion coefficient and the rate of vapor flux impinging on the substrate. The minimum drop radius increases with the diffusion coefficient and the impinging vapor flux; however, the dependence is weak. The minimum drop radius predicted from thermodynamic considerations matches the prediction of the cluster model, though the former does not take into account the effect of the surface properties on the nucleation phenomena. For a chemically passive surface, the diffusion coefficient and the residence time are dependent on the surface texture via the coefficient of friction. Thus, physical texturing provides a means of changing, within limits, the minimum drop radius. The study reveals that surface texturing at the scale of the minimum drop radius does not provide controllability of the macro-scale dropwise condensation at large timescales when a dynamic steady-state is reached.« less

  8. Filter aids influence on pressure drop across a filtration system

    NASA Astrophysics Data System (ADS)

    Hajar, S.; Rashid, M.; Nurnadia, A.; Ammar, M. R.; Hasfalina, C. M.

    2017-06-01

    Filter aids is commonly used to reduce pressure drop across air filtration system as it helps to increase the efficiency of filtration of accumulated filter cake. Filtration velocity is one of the main parameters that affect the performance of filter aids material. In this study, a formulated filter aids consisting of PreKot™ and activated carbon mixture (designated as PrekotAC) was tested on PTFE filter media under various filtration velocities of 5, 6, and 8 m/min at a constant material loading of 0.2 mg/mm2. Results showed that pressure drop is highly influenced by filtration velocity where higher filtration velocity leads to a higher pressure drop across the filter cake. It was found that PrekotAC performed better in terms of reducing the pressure drop across the filter cake even at the highest filtration velocity. The diversity in different particle size distribution of non-uniform particle size in the formulated PrekotAC mixture presents a higher permeability causes a lower pressure drop across the accumulated filter cake. The finding suggests that PrekotAC is a promising filter aids material that helps reducing the pressure drop across fabric filtration system.

  9. Experimental investigation of air pressure affecting filtration performance of fibrous filter sheet.

    PubMed

    Xu, Bin; Yu, Xiao; Wu, Ya; Lin, Zhongping

    2017-03-01

    Understanding the effect of air pressure on their filtration performance is important for assessing the effectiveness of fibrous filters under different practical circumstances. The effectiveness of three classes of air filter sheets were investigated in laboratory-based measurements at a wide range of air pressures (60-130 KPa). The filtration efficiency was found most sensitive to the air pressure change at smaller particle sizes. As the air pressure increased from 60 to 130 KPa, significant decrease in filtration efficiency (up to 15%) and increase in pressure drop (up to 90 Pa) were observed. The filtration efficiency of the filter sheet with largest fiber diameter and smallest solid volume fraction was affected most, while the pressure drop of the filter sheet with smallest fiber diameter and largest solid volume fraction was affected most. The effect of air pressure on the filtration efficiency was slightly larger at greater filter face air velocity. However, the effect of air pressure on the pressure drop was negligible. The filtration efficiency and pressure drop were explicitly expressed as functions of the air pressure. Two coefficients were empirically derived and successfully accounted for the effects of air pressure on filtration efficiency and pressure drop.

  10. Effect of flow rate and temperature on transmembrane blood pressure drop in an extracorporeal artificial lung.

    PubMed

    Park, M; Costa, E L V; Maciel, A T; Barbosa, E V S; Hirota, A S; Schettino, G de P; Azevedo, L C P

    2014-11-01

    Transmembrane pressure drop reflects the resistance of an artificial lung system to blood transit. Decreased resistance (low transmembrane pressure drop) enhances blood flow through the oxygenator, thereby, enhancing gas exchange efficiency. This study is part of a previous one where we observed the behaviour and the modulation of blood pressure drop during the passage of blood through artificial lung membranes. Before and after the induction of multi-organ dysfunction, the animals were instrumented and analysed for venous-venous extracorporeal membrane oxygenation, using a pre-defined sequence of blood flows. Blood flow and revolutions per minute (RPM) of the centrifugal pump varied in a linear fashion. At a blood flow of 5.5 L/min, pre- and post-pump blood pressures reached -120 and 450 mmHg, respectively. Transmembrane pressures showed a significant spread, particularly at blood flows above 2 L/min; over the entire range of blood flow rates, there was a positive association of pressure drop with blood flow (0.005 mmHg/mL/minute of blood flow) and a negative association of pressure drop with temperature (-4.828 mmHg/(°Celsius). These associations were similar when blood flows of below and above 2000 mL/minute were examined. During its passage through the extracorporeal system, blood is exposed to pressure variations from -120 to 450 mmHg. At high blood flows (above 2 L/min), the drop in transmembrane pressure becomes unpredictable and highly variable. Over the entire range of blood flows investigated (0-5500 mL/min), the drop in transmembrane pressure was positively associated with blood flow and negatively associated with body temperature. © The Author(s) 2014.

  11. Technical Consultation of the International Space Station (ISS) Internal Active Thermal Control System (IATCS) Cooling Water Chemistry

    NASA Technical Reports Server (NTRS)

    Gentz, Steven J.; Rotter, Hank A.; Easton, Myriam; Lince, Jeffrey; Park, Woonsup; Stewart, Thomas; Speckman, Donna; Dexter, Stephen; Kelly, Robert

    2005-01-01

    The Internal Active Thermal Control System (IATCS) coolant exhibited unexpected chemical changes during the first year of on-orbit operation following the launch and activation in February 2001. The coolant pH dropped from 9.3 to below the minimum specification limit of 9.0, and re-equilibrated between 8.3 and 8.5. This drop in coolant pH was shown to be the result of permeation of CO2 from the cabin into the coolant via Teflon flexible hoses which created carbonic acid in the fluid. This unexpected diffusion was the result of having a cabin CO2 partial pressure higher than the ground partial pressure (average 4.0 mmHg vs. less than 0.2 mmHg). This drop in pH was followed by a concurrent increasing coolant nickel concentration. No other metal ions were observed in the coolant and based on previous tests, the source of nickel ion was thought to be the boron nickel (BNi) braze intermetallics used in the construction of HXs and cold plates. Specifically, BNi2 braze alloy was used for the IATCS IFHX and BNi3 braze alloy was used for the IATCS Airlock Servicing and Performance Checkout Unit (SPCU) HX and cold plates. Given the failure criticality of the HXs, a Corrosion Team was established by the IATCS CWG to determine the impact of the nickel corrosion on hardware performance life.

  12. [Trial of eye drops recognizer for visually disabled persons].

    PubMed

    Okamoto, Norio; Suzuki, Katsuhiko; Mimura, Osamu

    2009-01-01

    The development of a device to enable the visually disabled to differentiate eye drops and their dose. The new instrument is composed of a voice generator and a two-dimensional bar-code reader (LS9208). We designed voice outputs for the visually disabled to state when (number of times) and where (right, left, or both) to administer eye drops. We then determined the minimum bar-code size that can be recognized. After attaching bar-codes of the appropriate size to the lateral or bottom surface of the eye drops container, the readability of the bar-codes was compared. The minimum discrimination bar-code size was 6 mm high x 8.5 mm long. Bar-codes on the bottom surface could be more easily recognized than bar-codes on the side. Our newly-developed device using bar-codes enables visually disabled persons to differentiate eye drops and their doses.

  13. 25 CFR 542.31 - What are the minimum internal control standards for drop and count for Tier B gaming operations?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... locked table game drop boxes shall be removed from the tables by a person independent of the pit shift... boxes shall be performed by a minimum of two persons, at least one of whom is independent of the pit... digital record, within seven (7) days by an employee independent of the count. (ii) [Reserved] (2) Count...

  14. Time-resolved optical emission spectroscopic studies of picosecond laser produced Cr plasma

    NASA Astrophysics Data System (ADS)

    Rao, Kavya H.; Smijesh, N.; Klemke, N.; Philip, R.; Litvinyuk, I. V.; Sang, R. T.

    2018-06-01

    Time-resolved optical emission spectroscopic measurements of a plasma generated by irradiating a Cr target using 60 picosecond (ps) and 300 ps laser pulses are carried out to investigate the variation in the line width (δλ) of emission from neutrals and ions for increasing ambient pressures. Measurements ranging from 10-6 Torr to 102 Torr show a distinctly different variation in the δλ of neutrals (Cr I) compared to that of singly ionized Cr (Cr II), for both irradiations. δλ increases monotonously with pressure for Cr II, but an oscillation is evident at intermediate pressures for Cr I. This oscillation does not depend on the laser pulse widths used. In spite of the differences in the plasma formation mechanisms, it is experimentally found that there is an optimum intermediate background pressure for which δλ of neutrals drops to a minimum. Importantly, these results underline the fact that for intermediate pressures, the usual practice of calculating the plasma number density from the δλ of neutrals needs to be judiciously done, to avoid reaching inaccurate conclusions.

  15. Pressure, temperature and density drops along supercritical fluid chromatography columns in different thermal environments. III. Mixtures of carbon dioxide and methanol as the mobile phase.

    PubMed

    Poe, Donald P; Veit, Devon; Ranger, Megan; Kaczmarski, Krzysztof; Tarafder, Abhijit; Guiochon, Georges

    2014-01-03

    The pressure, temperature and density drops along SFC columns eluted with a CO2/methanol mobile phase were measured and compared with theoretical values. For columns packed with 3- and 5-μm particles the pressure and temperature drops were measured using a mobile phase of 95% CO2 and 5% methanol at a flow rate of 5mL/min, at temperatures from 20 to 100°C, and outlet pressures from 80 to 300bar. The density drop was calculated based on the temperature and pressure at the column inlet and outlet. The columns were suspended in a circulating air bath, either bare or covered with foam insulation. The experimental measurements were compared to theoretical results obtained by numerical simulation. For the convective air condition at outlet pressures above 100bar the average difference between the experimental and calculated temperature drops and pressure drops were 0.1°C and 0.7% for the bare 3-μm column, respectively, and were 0.6°C and 4.1% for the insulated column. The observed temperature drops for the insulated columns are consistent with those predicted by the Joule-Thomson coefficients for isenthalpic expansion. The dependence of the temperature and the pressure drops on the Joule-Thomson coefficient and kinematic viscosity are described for carbon dioxide mobile phases containing up to 20% methanol. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Convective heat transfer and pressure drop of aqua based TiO2 nanofluids at different diameters of nanoparticles: Data analysis and modeling with artificial neural network

    NASA Astrophysics Data System (ADS)

    Hemmat Esfe, Mohammad; Nadooshan, Afshin Ahmadi; Arshi, Ali; Alirezaie, Ali

    2018-03-01

    In this study, experimental data related to the Nusselt number and pressure drop of aqueous nanofluids of Titania is modeled and estimated by using ANN with 2 hidden layers and 8 neurons in each layer. Also in this study the effect of various effective variables in the Nusselt number and pressure drop is surveyed. This study indicated that the neural network modeling has been able to model experimental data with great accuracy. The modeling regression coefficient for the data of Nusselt number and relative pressure drop is 99.94% and 99.97% respectively. Besides, it represented that the increment of the Reynolds number and concentration made the increment of Nusselt number and pressure drop of aqueous nanofluid.

  17. Influence of fuel temperature on atomization performance of pressure-swirl atomizers

    NASA Astrophysics Data System (ADS)

    Wang, X. F.; Lefebvre, A. H.

    The influence of fuel temperature on mean drop size and drop-size distribution is examined for aviation gasoline and diesel oil, using three pressure-swirl simplex nozzles. Spray characteristics are measured over wide ranges of fuel injection pressure and ambient air pressure using a Malvern spray analyzer. Fuel temperatures are varied from -20 C to +50 C. Over this range of temperature, the overall effect of an increase in fuel temperature is to reduce the mean drop size and broaden the distribution of drop sizes in the spray. Generally, it is found that the influence of fuel temperature on mean drop size is far more pronounced for diesel oil than for gasoline. For both fuels the beneficial effect of higher fuel temperatures on atomization quality is sensibly independent of ambient air pressure.

  18. Effect of External Pressure Drop on Loop Heat Pipe Operating Temperature

    NASA Technical Reports Server (NTRS)

    Jentung, Ku; Ottenstein, Laura; Rogers, Paul; Cheung, Kwok; Obenschain, Arthur F. (Technical Monitor)

    2002-01-01

    This paper discusses the effect of the pressure drop on the operating temperature in a loop heat pipe (LHP). Because the evaporator and the compensation chamber (CC) both contain two-phase fluid, a thermodynamic constraint exists between the temperature difference and the pressure drop for these two components. As the pressure drop increases, so will the temperature difference. The temperature difference in turn causes an increase of the heat leak from the evaporator to the CC, resulting in a higher CC temperature. Furthermore, the heat leak strongly depends on the vapor void fraction inside the evaporator core. Tests were conducted by installing a valve on the vapor line so as to vary the pressure drop, and by charging the LHP with various amounts of fluid. Test results verify that the LHP operating temperature increases with an increasing differential pressure, and the temperature increase is a strong function of the fluid inventory in the loop.

  19. Role of regression analysis and variation of rheological data in calculation of pressure drop for sludge pipelines.

    PubMed

    Farno, E; Coventry, K; Slatter, P; Eshtiaghi, N

    2018-06-15

    Sludge pumps in wastewater treatment plants are often oversized due to uncertainty in calculation of pressure drop. This issue costs millions of dollars for industry to purchase and operate the oversized pumps. Besides costs, higher electricity consumption is associated with extra CO 2 emission which creates huge environmental impacts. Calculation of pressure drop via current pipe flow theory requires model estimation of flow curve data which depends on regression analysis and also varies with natural variation of rheological data. This study investigates impact of variation of rheological data and regression analysis on variation of pressure drop calculated via current pipe flow theories. Results compare the variation of calculated pressure drop between different models and regression methods and suggest on the suitability of each method. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Heat exchangers in regenerative gas turbine cycles

    NASA Astrophysics Data System (ADS)

    Nina, M. N. R.; Aguas, M. P. N.

    1985-09-01

    Advances in compact heat exchanger design and fabrication together with fuel cost rises continuously improve the attractability of regenerative gas turbine helicopter engines. In this study cycle parameters aiming at reduced specific fuel consumption and increased payload or mission range, have been optimized together with heat exchanger type and size. The discussion is based on a typical mission for an attack helicopter in the 900 kw power class. A range of heat exchangers is studied to define the most favorable geometry in terms of lower fuel consumption and minimum engine plus fuel weight. Heat exchanger volume, frontal area ratio and pressure drop effect on cycle efficiency are considered.

  1. Flow rate-pressure drop relation for deformable shallow microfluidic channels

    NASA Astrophysics Data System (ADS)

    Christov, Ivan C.; Cognet, Vincent; Shidhore, Tanmay C.; Stone, Howard A.

    2018-04-01

    Laminar flow in devices fabricated from soft materials causes deformation of the passage geometry, which affects the flow rate--pressure drop relation. For a given pressure drop, in channels with narrow rectangular cross-section, the flow rate varies as the cube of the channel height, so deformation can produce significant quantitative effects, including nonlinear dependence on the pressure drop [{Gervais, T., El-Ali, J., G\\"unther, A. \\& Jensen, K.\\ F.}\\ 2006 Flow-induced deformation of shallow microfluidic channels.\\ \\textit{Lab Chip} \\textbf{6}, 500--507]. Gervais et. al. proposed a successful model of the deformation-induced change in the flow rate by heuristically coupling a Hookean elastic response with the lubrication approximation for Stokes flow. However, their model contains a fitting parameter that must be found for each channel shape by performing an experiment. We present a perturbation approach for the flow rate--pressure drop relation in a shallow deformable microchannel using the theory of isotropic quasi-static plate bending and the Stokes equations under a lubrication approximation (specifically, the ratio of the channel's height to its width and of the channel's height to its length are both assumed small). Our result contains no free parameters and confirms Gervais et. al.'s observation that the flow rate is a quartic polynomial of the pressure drop. The derived flow rate--pressure drop relation compares favorably with experimental measurements.

  2. Pressure driven flow of superfluid 4He through a nanopipe

    NASA Astrophysics Data System (ADS)

    Botimer, Jeffrey; Taborek, Peter

    2016-09-01

    Pressure driven flow of superfluid helium through single high-aspect-ratio glass nanopipes into a vacuum has been studied for a wide range of pressure drop (0-30 bars), reservoir temperature (0.8-2.5 K), pipe lengths (1-30 mm), and pipe radii (131 and 230 nm). As a function of pressure drop we observe two distinct flow regimes above and below a critical pressure drop Pc. For P

  3. A systematic search of sudden pressure drops on Gale crater during two Martian years derived from MSL/REMS data

    NASA Astrophysics Data System (ADS)

    Ordonez-Etxeberria, Iñaki; Hueso, Ricardo; Sánchez-Lavega, Agustín

    2018-01-01

    The Mars Science Laboratory (MSL) rover carries a suite of meteorological detectors that constitute the Rover Environmental Monitoring Station (REMS) instrument. REMS investigates the meteorological conditions at Gale crater by obtaining high-frequency data of pressure, air and ground temperature, relative humidity, UV flux at the surface and wind intensity and direction with some limitations in the wind data. We have run a search of atmospheric pressure drops of short duration (< 25 s) and we present a statistical study of the frequency of these events in the REMS pressure data during its first 1417 sols (more than two Martian years). The identified daytime pressure drops could be caused by the close passages of warm vortices and dust devils. Previous systematic searches of warm vortices from REMS pressure data (Kahanpää et al., 2016; Steakley and Murphy, 2016) cover about one Martian year. We show that sudden pressure drops are twice more abundant in the second Martian year [sols 671-1339] than in the first one analyzed in previous works. The higher number of detections could be linked to a combination of different topography, higher altitudes (120 m above the landing site) and true inter-annual meteorological variability. We found 1129 events with a pressure drop larger than 0.5 Pa. Of these, 635 occurred during the local daytime (∼56%) and 494 were nocturnal. The most intense pressure drop (4.2 Pa) occurred at daytime on sol 1417 (areocentric solar longitude Ls = 195°) and was accompanied by a simultaneous decrease in the UV signal of 7.1%, pointing to a true dust devil. We also discuss similar but less intense simultaneous pressure and UV radiation drops that constitute 0.7% of all daytime events. Most of the intense daytime pressure drops with variations larger than 1.0 Pa occur when the difference between air and ground temperature is larger than 15 K. Statistically, the frequency of daytime pressure drops peaks close to noon (12:00-13:00 Local True Solar Time or LTST) with more events in spring and summer (Ls from 180° to 360°). The nocturnal sudden pressure drops concentrate in the 20:00-23:00 LTST time interval and they only occur in spring and summer. We interpret these nocturnal events as a consequence of local mechanically forced turbulence. This interpretation is consistent with published results from simulations with the MRAMS model (Rafkin et al., 2016) that predict a competition between local orographic circulation and global Hadley cell circulation at Gale crater at summer night-time that can enhance forced turbulence at the surface. Bursts of pressure drops appear on particular sols, especially at night-time. Most of the vortex bursts occurred when MSL was in the region called Pahrump Hills characterized by a complex terrain. A comparison of the daytime pressure drops from REMS data with published results from the Pathfinder and Phoenix missions shows that the frequency of daytime events at Gale crater in spring and summer is similar to the one previously found at other locations. Finally, we present possible correlations between MSL activity and some daytime pressure drops. If such an instrumental effect is present in the REMS data its impact in this analysis is small and would only affect about 7% of our detections.

  4. 46 CFR 39.30-1 - Operational requirements-TB/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... oxygen content of each area of that tank formed by each partial bulkhead must be measured at a point one... the requirements of this part. (b) The pressure drop through the vapor collection system from the most... rate versus the pressure drop. (c) If a vessel carries vapor hoses, the pressure drop through the hoses...

  5. A novel generation of 3D SAR-based passive micromixer: efficient mixing and low pressure drop at a low Reynolds number

    NASA Astrophysics Data System (ADS)

    Viktorov, Vladimir; Nimafar, Mohammad

    2013-05-01

    This study introduces a novel generation of 3D splitting and recombination (SAR) passive micromixer with microstructures placed on the top and bottom floors of microchannels called a ‘chain mixer’. Both experimental verification and numerical analysis of the flow structure of this type of passive micromixer have been performed to evaluate the mixing performance and pressure drop of the microchannel, respectively. We propose here two types of chain mixer—chain 1 and chain 2—and compare their mixing performance and pressure drop with other micromixers, T-, o- and tear-drop micromixers. Experimental tests carried out in the laminar flow regime with a low Reynolds number range, 0.083 ≤ Re ≤ 4.166, and image-based techniques are used to evaluate the mixing efficiency. Also, the computational fluid dynamics code, ANSYS FLUENT-13.0 has been used to analyze the flow and pressure drop in the microchannel. Experimental results show that the chain and tear-drop mixer's efficiency is very high because of the SAR process: specifically, an efficiency of up to 98% can be achieved at the tested Reynolds number. The results also show that chain mixers have a lower required pressure drop in comparison with a tear-drop micromixer.

  6. Sound field inside acoustically levitated spherical drop

    NASA Astrophysics Data System (ADS)

    Xie, W. J.; Wei, B.

    2007-05-01

    The sound field inside an acoustically levitated small spherical water drop (radius of 1mm) is studied under different incident sound pressures (amplitude p0=2735-5643Pa). The transmitted pressure ptr in the drop shows a plane standing wave, which varies mainly in the vertical direction, and distributes almost uniformly in the horizontal direction. The maximum of ptr is always located at the lowermost point of the levitated drop. Whereas the secondary maximum appears at the uppermost point if the incident pressure amplitude p0 is higher than an intermediate value (3044Pa), in which there exists a pressure nodal surface in the drop interior. The value of the maximum ptr lies in a narrow range of 2489-3173Pa, which has a lower limit of 2489Pa when p0=3044Pa. The secondary maximum of ptr is rather small and only remarkable at high incident pressures.

  7. Optimization of a Circular Microchannel With Entropy Generation Minimization Method

    NASA Astrophysics Data System (ADS)

    Jafari, Arash; Ghazali, Normah Mohd

    2010-06-01

    New advances in micro and nano scales are being realized and the contributions of micro and nano heat dissipation devices are of high importance in this novel technology development. Past studies showed that microchannel design depends on its thermal resistance and pressure drop. However, entropy generation minimization (EGM) as a new optimization theory stated that the rate of entropy generation should be also optimized. Application of EGM in microchannel heat sink design is reviewed and discussed in this paper. Latest principles for deriving the entropy generation relations are discussed to present how this approach can be achieved. An optimization procedure using EGM method with the entropy generation rate is derived for a circular microchannel heat sink based upon thermal resistance and pressure drop. The equations are solved using MATLAB and the obtained results are compared to similar past studies. The effects of channel diameter, number of channels, heat flux, and pumping power on the entropy generation rate and Reynolds number are investigated. Analytical correlations are utilized for heat transfer and friction coefficients. A minimum entropy generation has been observed for N = 40 and channel diameter of 90μm. It is concluded that for N = 40 and channel hydraulic diameter of 90μm, the circular microchannel heat sink is on its optimum operating point based on second law of thermodynamics.

  8. Pressure drop in tubing in aircraft instrument installations

    NASA Technical Reports Server (NTRS)

    Wildhack, W A

    1937-01-01

    The theoretical basis of calculation of pressure drop in tubing is reviewed briefly. The effect of pressure drop in connecting tubing upon the operation and indication of aircraft instruments is discussed. Approximate equations are developed, and charts and tables based upon them are presented for use in designing installations of altimeters, air-speed indicators, rate-of-climb indicators, and air-driven gyroscopic instruments.

  9. CFD-DEM modeling the effect of column size and bed height on minimum fluidization velocity in micro fluidized beds with Geldart B particles

    DOE PAGES

    Xu, Yupeng; Li, Tingwen; Musser, Jordan; ...

    2017-06-07

    The fluidization behavior of Geldart B particles in micro fluidized beds is investigated numerically using Computational Fluid Dynamics coupled with Discrete Element Method (CFD-DEM) available in the open-source Multiphase Flow with Interphase eXchanges (MFIX) code. The effects of different bed inner diameters (D) of 8 mm, 12 mm, 16 mm and various initial static bed heights (H) were examined. It is found that both decreasing the column diameter and increasing the bed height in a micro fluidized bed increases the minimum fluidization velocity (Umf). The observed overshoot in pressure drop that occurs before the onset of fluidization decreases in magnitudemore » with increasing column diameter, however there is less sensitivity to bed height. Overall, the numerical results agree qualitatively with existing theoretical correlations and experimental studies. The simulations show that both column diameter and particle-wall friction contribute to the variation in minimum fluidization velocity. Finally, these two factors are coupled and hard to separate. The detailed influences of wall friction on minimum fluidization velocity are then investigated for a prescribed column diameter of 8 mm by varying the wall friction from 0 to 0.4.« less

  10. CFD-DEM modeling the effect of column size and bed height on minimum fluidization velocity in micro fluidized beds with Geldart B particles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Yupeng; Li, Tingwen; Musser, Jordan

    The fluidization behavior of Geldart B particles in micro fluidized beds is investigated numerically using Computational Fluid Dynamics coupled with Discrete Element Method (CFD-DEM) available in the open-source Multiphase Flow with Interphase eXchanges (MFIX) code. The effects of different bed inner diameters (D) of 8 mm, 12 mm, 16 mm and various initial static bed heights (H) were examined. It is found that both decreasing the column diameter and increasing the bed height in a micro fluidized bed increases the minimum fluidization velocity (Umf). The observed overshoot in pressure drop that occurs before the onset of fluidization decreases in magnitudemore » with increasing column diameter, however there is less sensitivity to bed height. Overall, the numerical results agree qualitatively with existing theoretical correlations and experimental studies. The simulations show that both column diameter and particle-wall friction contribute to the variation in minimum fluidization velocity. Finally, these two factors are coupled and hard to separate. The detailed influences of wall friction on minimum fluidization velocity are then investigated for a prescribed column diameter of 8 mm by varying the wall friction from 0 to 0.4.« less

  11. Method and means for producing solid evacuated microspheres of hydrogen

    DOEpatents

    Turnbull, Robert J.; Foster, Christopher A.; Hendricks, Charles D.

    1976-01-01

    A method is provided for producing solid, evacuated microspheres comprised of hydrogen. The spheres are produced by forming a jet of liquid hydrogen and exciting mechanical waves on the jet of appropriate frequency so that the jet breaks up into drops with a bubble formed in each drop by cavitation. The drops are exposed to a pressure less than the vapor pressure of the liquid hydrogen so that the bubble which is formed within each drop expands. The drops which contain bubbles are exposed to an environment having a pressure just below the triple point of liquid hydrogen and they thereby freeze giving solid, evacuated spheres of hydrogen.

  12. Solid evacuated microspheres of hydrogen

    DOEpatents

    Turnbull, Robert J.; Foster, Christopher A.; Hendricks, Charles D.

    1982-01-01

    A method is provided for producing solid, evacuated microspheres comprised of hydrogen. The spheres are produced by forming a jet of liquid hydrogen and exciting mechanical waves on the jet of appropriate frequency so that the jet breaks up into drops with a bubble formed in each drop by cavitation. The drops are exposed to a pressure less than the vapor pressure of the liquid hydrogen so that the bubble which is formed within each drop expands. The drops which contain bubbles are exposed to an environment having a pressure just below the triple point of liquid hydrogen and they thereby freeze giving solid, evacuated spheres of hydrogen.

  13. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or... of 0.45 cubic meters (15.9 cubic feet) or less must be subject to an additional drop test. (e) Drop... having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...

  14. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or... of 0.45 cubic meters (15.9 cubic feet) or less must be subject to an additional drop test. (e) Drop... having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...

  15. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... Water/anti-freeze solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or... of 0.45 cubic meters (15.9 cubic feet) or less must be subject to an additional drop test. (e) Drop... having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...

  16. Heat loss and drag of spherical drop tube samples

    NASA Technical Reports Server (NTRS)

    Wallace, D. B.

    1982-01-01

    Analysis techniques for three aspects of the performance of the NASA/MSFC 32 meter drop tube are considered. Heat loss through the support wire in a pendant drop sample, temperature history of a drop falling through the drop tube when the tube is filled with helium gas at various pressures, and drag and resulting g-levels experienced by a drop falling through the tube when the tube is filled with helium gas at various pressures are addressed. The developed methods apply to systems with sufficiently small Knudsen numbers for which continuum theory may be applied. Sample results are presented, using niobium drops, to indicate the magnitudes of the effects. Helium gas at one atmosphere pressure can approximately double the amount of possible undercooling but it results in an apparent gravity levels of up to 0.1 g.

  17. Combining spray nozzle simulators with meshes: characterization of rainfall intensity and drop properties

    NASA Astrophysics Data System (ADS)

    Carvalho, Sílvia C. P.; de Lima, João L. M. P.; de Lima, M. Isabel P.

    2013-04-01

    Rainfall simulators can be a powerful tool to increase our understanding of hydrological and geomorphological processes. Nevertheless, rainfall simulators' design and operation might be rather demanding, for achieving specific rainfall intensity distributions and drop characteristics. The pressurized simulators have some advantages over the non-pressurized simulators: drops do not rely on gravity to reach terminal velocity, but are sprayed out under pressure; pressurized simulators also yield a broad range of drop sizes in comparison with drop-formers simulators. The main purpose of this study was to explore in the laboratory the potential of combining spray nozzle simulators with meshes in order to change rainfall characteristics (rainfall intensity and diameters and fall speed of drops). Different types of spray nozzles were tested, such as single full-cone and multiple full-cone nozzles. The impact of the meshes on the simulated rain was studied by testing different materials (i.e. plastic and steel meshes), square apertures and wire thicknesses, and different vertical distances between the nozzle and the meshes underneath. The diameter and fall speed of the rain drops were measured using a Laser Precipitation Monitor (Thies Clima). The rainfall intensity range and coefficients of uniformity of the sprays and the drop size distribution, fall speed and kinetic energy were analysed. Results show that when meshes intercept drop trajectories the spatial distribution of rainfall intensity and the drop size distribution are affected. As the spray nozzles generate typically small drop sizes and narrow drop size distributions, meshes can be used to promote the formation of bigger drops and random their landing positions.

  18. System for Manipulating Drops and Bubbles Using Acoustic Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C. (Inventor)

    1999-01-01

    The manipulation and control of drops of liquid and gas bubbles is achieved using high intensity acoustics in the form of and/or acoustic radiation pressure and acoustic streaming. generated by a controlled wave emission from a transducer. Acoustic radiation pressure is used to deploy or dispense drops into a liquid or a gas or bubbles into a liquid at zero or near zero velocity from the discharge end of a needle such as a syringe needle. Acoustic streaming is useful in manipulating the drop or bubble during or after deployment. Deployment and discharge is achieved by focusing the acoustic radiation pressure on the discharge end of the needle, and passing the acoustic waves through the fluid in the needle. through the needle will itself, or coaxially through the fluid medium surrounding the needle. Alternatively, the acoustic waves can be counter-deployed by focusing on the discharge end of the needle from a transducer axially aligned with the needle, but at a position opposite the needle, to prevent premature deployment of the drop or bubble. The acoustic radiation pressure can also be used for detecting the presence or absence of a drop or a bubble at the tip of a needle or for sensing various physical characteristics of the drop or bubble such as size or density.

  19. Passively actuated valve

    DOEpatents

    Modro, S. Michael; Ougouag, Abderrafi M.

    2005-09-20

    A passively actuated valve for isolating a high pressure zone from a low pressure zone and discontinuing the isolation when the pressure in the high pressure zone drops below a preset threshold. If the pressure in the high pressure zone drops below the preset threshold, the valve opens and allows flow from the high pressure zone to the low pressure zone. The valve remains open allowing pressure equalization and back-flow should a pressure inversion between the two pressure zone occur.

  20. Investigation of powder injection moulded oblique fin heat sinks

    NASA Astrophysics Data System (ADS)

    Sai, Vadri Siva

    The present work attempts to study the fluid flow and heat transfer characteristics of PIM oblique finned microchannel heat sink both numerically and experimentally. Experimental results such as thermal resistance and pressure drop have been well validated with ANSYS FLUENT simulations. Hot spots are observed at the most downstream location of the channel is due to the effect of flow migration. Finally, a novel technique has been proposed to reduce the pressure drop on creating additional channels by removing some material at the middle portion of oblique fins. It is found that the creation of oblique cuts incurred a reduction in both pressure drop and Nuavg up to 31.36 % and 16.66 % respectively at a flow rate of 500 ml/min. Nevertheless, for all the flowrates considered in this analysis. % reduction in pressure drop is almost double as compared with % reduction in Nuavg. Therefore, this analysis is beneflcial in reducing the additional cost incurs due to pressure drop penalty.

  1. Experimental investigation into vortex structure and pressure drop across microcavities in 3D integrated electronics

    NASA Astrophysics Data System (ADS)

    Renfer, Adrian; Tiwari, Manish K.; Brunschwiler, Thomas; Michel, Bruno; Poulikakos, Dimos

    2011-09-01

    Hydrodynamics in microcavities with cylindrical micropin fin arrays simulating a single layer of a water-cooled electronic chip stack is investigated experimentally. Both inline and staggered pin arrangements are investigated using pressure drop and microparticle image velocimetry (μPIV) measurements. The pressure drop across the cavity shows a flow transition at pin diameter-based Reynolds numbers ( Re d ) ~200. Instantaneous μPIV, performed using a pH-controlled high seeding density of tracer microspheres, helps visualize vortex structure unreported till date in microscale geometries. The post-transition flow field shows vortex shedding and flow impingement onto the pins explaining the pressure drop increase. The flow fluctuations start at the chip outlet and shift upstream with increasing Re d . No fluctuations are observed for a cavity with pin height-to-diameter ratio h/ d = 1 up to Re d ~330; however, its pressure drop was higher than for a cavity with h/d = 2 due to pronounced influence of cavity walls.

  2. Heat transfer and pressure drop for air flow through enhanced passages

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effectmore » depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.« less

  3. Heat transfer and pressure drop for air flow through enhanced passages. Final report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effectmore » depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.« less

  4. Beyond Bernoulli

    PubMed Central

    Donati, Fabrizio; Myerson, Saul; Bissell, Malenka M.; Smith, Nicolas P.; Neubauer, Stefan; Monaghan, Mark J.; Nordsletten, David A.

    2017-01-01

    Background— Transvalvular peak pressure drops are routinely assessed noninvasively by echocardiography using the Bernoulli principle. However, the Bernoulli principle relies on several approximations that may not be appropriate, including that the majority of the pressure drop is because of the spatial acceleration of the blood flow, and the ejection jet is a single streamline (single peak velocity value). Methods and Results— We assessed the accuracy of the Bernoulli principle to estimate the peak pressure drop at the aortic valve using 3-dimensional cardiovascular magnetic resonance flow data in 32 subjects. Reference pressure drops were computed from the flow field, accounting for the principles of physics (ie, the Navier–Stokes equations). Analysis of the pressure components confirmed that the spatial acceleration of the blood jet through the valve is most significant (accounting for 99% of the total drop in stenotic subjects). However, the Bernoulli formulation demonstrated a consistent overestimation of the transvalvular pressure (average of 54%, range 5%–136%) resulting from the use of a single peak velocity value, which neglects the velocity distribution across the aortic valve plane. This assumption was a source of uncontrolled variability. Conclusions— The application of the Bernoulli formulation results in a clinically significant overestimation of peak pressure drops because of approximation of blood flow as a single streamline. A corrected formulation that accounts for the cross-sectional profile of the blood flow is proposed and adapted to both cardiovascular magnetic resonance and echocardiographic data. PMID:28093412

  5. Biomass plug development and propagation in porous media.

    PubMed

    Stewart, T L; Fogler, H S

    2001-02-05

    Exopolymer-producing bacteria can be used to modify soil profiles for enhanced oil recovery or bioremediation. Understanding the mechanisms associated with biomass plug development and propagation is needed for successful application of this technology. These mechanisms were determined from packed-bed and micromodel experiments that simulate plugging in porous media. Leuconostoc mesenteroides was used, because production of dextran, a water-insoluble exopolymer, can be controlled by using different carbon sources. As dextran was produced, the pressure drop across the porous media increased and began to oscillate. Three pressure phases were identified under exopolymer-producing conditions: the exopolymer-induction phase, the plugging phase, and the plug-propagation phase. The exopolymer-induction phase extended from the time that exopolymer-producing conditions were induced until there was a measurable increase in pressure drop across the porous media. The plugging phase extended from the first increase in pressure drop until a maximum pressure drop was reached. Changes in pressure drop in these two phases were directly related to biomass distribution. Specifically, flow channels within the porous media filled with biomass creating a plugged region where convective flow occurred only in water channels within the biofilm. These water channels were more restrictive to flow causing the pressure drop to increase. At a maximum pressure drop across the porous media, the biomass yielded much like a Bingham plastic, and a flow channel was formed. This behavior marked the onset of the plug-propagation phase which was characterized by sequential development and breakthrough of biomass plugs. This development and breakthrough propagated the biomass plug in the direction of nutrient flow. The dominant mechanism associated with all three phases of plugging in porous media was exopolymer production; yield stress is an additional mechanism in the plug-propagation phase. Copyright 2001 John Wiley & Sons, Inc.

  6. An investigation of two phase flow pressure drops in a reduced acceleration environment

    NASA Astrophysics Data System (ADS)

    Wheeler, Montgomery W.; Best, Frederick R.; Reinarts, Thomas R.

    1993-01-01

    Thermal systems for space applications based on two phase flow have several advantages over single phase systems. Two phase thermal energy management and dynamic power conversion system advantages include the capability of achieving high specific power levels. Before two phase systems for space applications can be designed effectively, knowledge of the flow behavior in a reduced acceleration environment is necessary. To meet these needs, two phase flow experiments were conducted aboard the National Aeronautic and Space Administration's KC-135 using R12 as the working fluid. Annular flow two phase pressure drops were measured through 10.41-mm ID 1.251-m long glass tubing during periods with acceleration levels in the range ±0.05 G. The experiments were conducted with emphasis on achieving data with a high level of accuracy. The reduced acceleration annular flow pressure drops were compred with pressure drops measured in a 1-G environment for similar flow conditions. The reduced acceleration pressure drops were found to be 45% greater than the 1-G pressure drops. In addition, the reduced acceleration annular flow interfacial friction factors were compared with models for vertical up-flow in a 1-G environment. The reduced acceleration interfacial friction factor data was not predicted by the 1-G models.

  7. Estimation of methacrylate monolith binding capacity from pressure drop data.

    PubMed

    Podgornik, Aleš; Smrekar, Vida; Krajnc, Peter; Strancar, Aleš

    2013-01-11

    Convective chromatographic media comprising of membranes and monoliths represent an important group of chromatographic supports due to their flow-unaffected chromatographic properties and consequently fast separation and purification even of large biological macromolecules. Consisting of a single piece of material, common characterization procedures based on analysis of a small sample assuming to be representative for the entire batch, cannot be applied. Because of that, non-invasive characterization methods are preferred. In this work pressure drop was investigated for an estimation of dynamic binding capacity (DBC) of proteins and plasmid DNA for monoliths with different pore sizes. It was demonstrated that methacrylate monolith surface area is reciprocally proportional to pore diameter and that pressure drop on monolith is reciprocally proportional to square pore size demonstrating that methacrylate monolith microstructure is preserved by changing pore size. Based on these facts mathematical formalism has been derived predicting that DBC is in linear correlation with the square root of pressure drop. This was experimentally confirmed for ion-exchange and hydrophobic interactions for proteins and plasmid DNA. Furthermore, pressure drop was also applied for an estimation of DBC in grafted layers of different thicknesses as estimated from the pressure drop data. It was demonstrated that the capacity is proportional to the estimated grafted layer thickness. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. 29 CFR 1926.104 - Safety belts, lifelines, and lanyards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... be subjected to cutting or abrasion, shall be a minimum of 7/8-inch wire core manila rope. For all other lifeline applications, a minimum of 3/4-inch manila or equivalent, with a minimum breaking... nominal breaking strength of 5,400 pounds. (e) All safety belt and lanyard hardware shall be drop forged...

  9. 29 CFR 1926.104 - Safety belts, lifelines, and lanyards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... be subjected to cutting or abrasion, shall be a minimum of 7/8-inch wire core manila rope. For all other lifeline applications, a minimum of 3/4-inch manila or equivalent, with a minimum breaking... nominal breaking strength of 5,400 pounds. (e) All safety belt and lanyard hardware shall be drop forged...

  10. 29 CFR 1926.104 - Safety belts, lifelines, and lanyards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... be subjected to cutting or abrasion, shall be a minimum of 7/8-inch wire core manila rope. For all other lifeline applications, a minimum of 3/4-inch manila or equivalent, with a minimum breaking... nominal breaking strength of 5,400 pounds. (e) All safety belt and lanyard hardware shall be drop forged...

  11. Resonances, radiation pressure and optical scattering phenomena of drops and bubbles

    NASA Technical Reports Server (NTRS)

    Marston, P. L.; Goosby, S. G.; Langley, D. S.; Loporto-Arione, S. E.

    1982-01-01

    Acoustic levitation and the response of fluid spheres to spherical harmonic projections of the radiation pressure are described. Simplified discussions of the projections are given. A relationship between the tangential radiation stress and the Konstantinov effect is introduced and fundamental streaming patterns for drops are predicted. Experiments on the forced shape oscillation of drops are described and photographs of drop fission are displayed. Photographs of critical angle and glory scattering by bubbles and rainbow scattering by drops are displayed.

  12. The pressure field of imploding lightbulbs

    NASA Astrophysics Data System (ADS)

    Czechanowski, M.; Ikeda, C.; Duncan, J. H.

    2015-03-01

    The implosion of A19 incandescent lightbulbs in a high-pressure water environment is studied in a 1.77-m-diameter steel tank. Underwater blast sensors are used to measure the dynamic pressure field near the lightbulbs and the implosions are photographed with a high-speed movie camera at a frame rate of 24,000 pps. The movie camera and the pressure signal recording system are synchronized to enable correlation of features in the movie frames with those in the pressure records. It is found that the gross dimensions and weight of the bulbs are very similar from one bulb to another, but the ambient water pressure at which a given bulb implodes (, called the implosion pressure) varies from 6.29 to 11.98 atmospheres, probably due to inconsistencies in the glass wall thickness and perhaps other detailed characteristics of the bulbs. The dynamic pressures (the local pressure minus , as measured by the sensors) first drop during the implosion and then reach a strong positive peak at about the time that the bulb reaches minimum volume. The peak dynamic pressure varies from 3.61 to 28.66 atmospheres. In order to explore the physics of the implosion process, the dynamic pressure signals are compared to calculations of the pressure field generated by the collapse of a spherical bubble in a weakly compressible liquid. The wide range of implosion pressures is used in combination with the calculations to explore the effect of the relative liquid compressibility and the bulb itself on the dynamic pressure field.

  13. Two-phase pressure drop in a helical coil flow boiling system

    NASA Astrophysics Data System (ADS)

    Hardik, B. K.; Prabhu, S. V.

    2018-05-01

    The objective of the present work is to study the two-phase pressure drop in helical coils. Literature on the two-phase pressure drop in a helical coil suggests the complexity in flow boiling inside a helical coil due to secondary flow. Most of correlations reported in the literature on the two-phase pressure drop in a helical coil are limited to a specific operating range. No general correlation is available for a helical coil which is applicable for all fluids. In the present study, an experimental databank collected containing a total of 832 data points includes the data from the present study and from the literature. The data includes diabatic pressure drop of two fluids namely water and R123. Data covers a range of parameters namely a mass flux of 120-2058 kg/m2 s, a heat flux of 18-2831 kW/m2, an exit quality of 0.03-1, a density ratio of 32-1404 and a coil to tube diameter ratio of 14-58. The databank is compared with eighteen empirical correlations which include well referred correlations of straight tubes and the available correlations of helical coils. The straight tube correlations are not working well for the present data set. The helical coil correlations work reasonably well for the present databank. A correlation is suggested to predict the two-phase pressure drop in helical coils. The present study suggests that the influence of a helical coil is completely included in the single phase pressure drop correlation for helical coils.

  14. A study of nonlinear dynamics of single- and two-phase flow oscillations

    NASA Astrophysics Data System (ADS)

    Mawasha, Phetolo Ruby

    The dynamics of single- and two-phase flows in channels can be contingent on nonlinearities which are not clearly understood. These nonlinearities could be interfacial forces between the flowing fluid and its walls, variations in fluid properties, growth of voids, etc. The understanding of nonlinear dynamics of fluid flow is critical in physical systems which can undergo undesirable system operating scenarios such an oscillatory behavior which may lead to component failure. A nonlinear lumped mathematical model of a surge tank with a constant inlet flow into the tank and an outlet flow through a channel is derived from first principles. The model is used to demonstrate that surge tanks with inlet and outlet flows contribute to oscillatory behavior in laminar, turbulent, single-phase, and two-phase flow systems. Some oscillations are underdamped while others are self-sustaining. The mechanisms that are active in single-phase oscillations with no heating are presented using specific cases of simplified models. Also, it is demonstrated how an external mechanism such as boiling contributes to the oscillations observed in two-phase flow and gives rise to sustained oscillations (or pressure drop oscillations). A description of the pressure drop oscillation mechanism is presented using the steady state pressure drop versus mass flow rate characteristic curve of the heated channel, available steady state pressure drop versus mass flow rate from the surge tank, and the transient pressure drop versus mass flow rate limit cycle. Parametric studies are used to verify the theoretical pressure drop oscillations model using experimental data by Yuncu's (1990). The following contributions are unique: (1) comparisons of nonlinear pressure drop oscillation models with and without the effect of the wall thermal heat capacity and (2) comparisons of linearized pressure drop oscillation models with and without the effect of the wall thermal heat capacity to identify stability boundaries.

  15. Camphor-Crataegus berry extract combination dose-dependently reduces tilt induced fall in blood pressure in orthostatic hypotension.

    PubMed

    Belz, G G; Butzer, R; Gaus, W; Loew, D

    2002-10-01

    In order to test the efficacy of a combination of natural D-camphor and an extract of fresh crataegus berries (Korodin Herz-Kreislauf-Tropfen) on orthostatic hypotension, two similar, controlled, randomized studies were carried out in a balanced crossover design in 24 patients each with orthostatic dysregulation. The camphor-crataegus berry combination (CCC) was orally administered as a single regimen in 3 different dosages of 5 drops, 20 drops and 80 drops; a placebo with 20 drops of a 60% alcoholic solution served as control. Orthostatic hypotension was assessed with the tilt table test before and after medication. Source data of both studies were pooled and meta-analytically evaluated for all 48 patients. CCC drops decreased the orthostatic fall in blood pressure versus placebo, as almost uniformly established at all times by mean arterial pressure and diastolic blood pressure. Mean arterial pressure demonstrated the very fast onset of action by a clearly dose-dependent statistically significant effect even after 1-minute orthostasis. Increase of mean arterial pressure as compared to the orthostasis test before medication was on average 4.5 mmHg. CCC affected diastolic blood pressure after 1 minute of orthostasis in all dosages as compared to placebo. A statistically significant effect of the highest dose of 80 drops on diastolic blood pressure could be demonstrated after 1-, 3-, and 5-minute orthostasis. The hemodynamic findings of a stabilizing effect on arterial pressure in orthostasis corroborate the long-term medical experience with CCC and justify the indication orthostatic hypotension.

  16. Air cushioning in drop impact

    NASA Astrophysics Data System (ADS)

    de Ruiter, Jolet; Oh, Jung; van den Ende, Dirk; Mugele, Frieder

    2011-11-01

    Liquid drops impacting on solid surfaces deform under the influence of the ambient gas that needs to be squeezed out before a true solid-liquid contact can be established. We demonstrate experimentally the existence of this theoretically predicted air layer and follow its evolution with time for moderate impact speeds (We ~ 1 ... 10) using reflection interference microscopy with a thickness resolution of approximately 10nm. For a wide range of fluid properties (ρ, γ, η) we find a very robust generic behavior that includes the predicted formation of a dimple in the center of the drop with a local minimum of the air film thickness at its boundary. Depending on We as well as the fluid properties, a skating layer of more or less constant thickness as well as a second local minimum of the air film thickness farther away from the drop center develop in time. Eventually, solid-liquid contact is generated via random nucleation event. The nucleation spot spreads across the drop-substrate interface within a few milliseconds. This process can lead to the entrapment of an air bubble.

  17. Numerical Investigation of Temperature Distribution in an Eroded Bend Pipe and Prediction of Erosion Reduced Thickness

    PubMed Central

    Zhu, Hongjun; Feng, Guang; Wang, Qijun

    2014-01-01

    Accurate prediction of erosion thickness is essential for pipe engineering. The objective of the present paper is to study the temperature distribution in an eroded bend pipe and find a new method to predict the erosion reduced thickness. Computational fluid dynamic (CFD) simulations with FLUENT software are carried out to investigate the temperature field. And effects of oil inlet rate, oil inlet temperature, and erosion reduced thickness are examined. The presence of erosion pit brings about the obvious fluctuation of temperature drop along the extrados of bend. And the minimum temperature drop presents at the most severe erosion point. Small inlet temperature or large inlet velocity can lead to small temperature drop, while shallow erosion pit causes great temperature drop. The dimensionless minimum temperature drop is analyzed and the fitting formula is obtained. Using the formula we can calculate the erosion reduced thickness, which is only needed to monitor the outer surface temperature of bend pipe. This new method can provide useful guidance for pipeline monitoring and replacement. PMID:24719576

  18. Enantioseparation of omeprazole--effect of different packing particle size on productivity.

    PubMed

    Enmark, Martin; Samuelsson, Jörgen; Forssén, Patrik; Fornstedt, Torgny

    2012-06-01

    Enantiomeric separation of omeprazole has been extensively studied regarding both product analysis and preparation using several different chiral stationary phases. In this study, the preparative chiral separation of omeprazole is optimized for productivity using three different columns packed with amylose tris (3,5-dimethyl phenyl carbamate) coated macroporous silica (5, 10 and 25 μm) with a maximum allowed pressure drop ranging from 50 to 400 bar. This pressure range both covers low pressure process systems (50-100 bar) and investigates the potential for allowing higher pressure limits in preparative applications in a future. The process optimization clearly show that the larger 25 μm packing material show higher productivity at low pressure drops whereas with increasing pressure drops the smaller packing materials have substantially higher productivity. Interestingly, at all pressure drops, the smaller packing material result in lower solvent consumption (L solvent/kg product); the higher the accepted pressure drop, the larger the gain in reduced solvent consumption. The experimental adsorption isotherms were not identical for the different packing material sizes; therefore all calculations were recalculated and reevaluated assuming identical adsorption isotherms (with the 10 μm isotherm as reference) which confirmed the trends regarding productivity and solvent consumption. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. On the collapse pressure of armored bubbles and drops.

    PubMed

    Pitois, O; Buisson, M; Chateau, X

    2015-05-01

    Drops and bubbles wrapped in dense monolayers of hydrophobic particles are known to sustain a significant decrease of their internal pressure. Through dedicated experiments we investigate the collapse behavior of such armored water drops as a function of the particle-to-drop size ratio in the range 0.02-0.2. We show that this parameter controls the behavior of the armor during the deflation: at small size ratios the drop shrinkage proceeds through the soft crumpling of the monolayer, at intermediate ratios the drop becomes faceted, and for the largest studied ratios the armor behaves like a granular arch. The results show that each of the three morphological regimes is characterized by an increasing magnitude of the collapse pressure. This increase is qualitatively modeled thanks to a mechanism involving out-of-plane deformations and particle disentanglement in the armor.

  20. Method for reducing pressure drop through filters, and filter exhibiting reduced pressure drop

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sappok, Alexander; Wong, Victor

    Methods for generating and applying coatings to filters with porous material in order to reduce large pressure drop increases as material accumulates in a filter, as well as the filter exhibiting reduced and/or more uniform pressure drop. The filter can be a diesel particulate trap for removing particulate matter such as soot from the exhaust of a diesel engine. Porous material such as ash is loaded on the surface of the substrate or filter walls, such as by coating, depositing, distributing or layering the porous material along the channel walls of the filter in an amount effective for minimizing ormore » preventing depth filtration during use of the filter. Efficient filtration at acceptable flow rates is achieved.« less

  1. High speed turbogenerator for power recovery from fluid flow within conduit

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Irvine, M. D.

    1985-11-26

    A high speed turbogenerator functionally combining, in one machine, an electrical generator and an expansion turbine. The electrical generator itself has a shaft supported on two bearings and the expansion turbine comprises an expander wheel overhung on the generator shaft and which rotates as a high pressure gas is let down in the expansion turbine to a lower pressure at a minimum predetermined flow rate and pressure drop. The shaft operates at speeds of about 6,000 rpm to 32,000 rpm, preferably at the higher end of such range, i.e. 20,000 to 24,000 rpm. The unit is sufficiently compact that amore » new use for the electrical generator is to modify the same such that the entire high speed turbogenerator is contained within the conduit carrying the gas to be let down in pressure and only electrical wires need be led through the conduit. The integrity of the conduit is thus retained to the extent possible and only a high pressure cable fitting extends through the conduit. In the preferred embodiment, the high speed turbogenerator is entirely fitted within a natural gas conduit in a gas distribution station, thereby achieving the pressure letdown and also obtaining useful electrical power.« less

  2. Remotely operated high pressure valve protects test personnel

    NASA Technical Reports Server (NTRS)

    Howland, B. T.

    1967-01-01

    High pressure valve used in testing certain spacecraft systems is safely opened and closed by a remotely stationed operator. The valve is self-regulating in that if the incoming pressure drops below a desired value the valve will automatically close, warning the operator that the testing pressure has dropped to an undesired level.

  3. Minimum Wages and School Enrollment of Teenagers: A Look at the 1990's.

    ERIC Educational Resources Information Center

    Chaplin, Duncan D.; Turner, Mark D.; Pape, Andreas, D.

    2003-01-01

    Estimates the effects of higher minimum wages on school enrollment using the Common Core of Data. Controlling for local labor market conditions and state and year fixed effects, finds some evidence that higher minimum wages reduce teen school enrollment in states where students drop out before age 18. (23 references) (Author/PKP)

  4. Investigation of pressure drop in capillary tube for mixed refrigerant Joule-Thomson cryocooler

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

    2014-01-29

    A capillary tube is commonly used in small capacity refrigeration and air-conditioning systems. It is also a preferred expansion device in mixed refrigerant Joule-Thomson (MR J-T) cryocoolers, since it is inexpensive and simple in configuration. However, the flow inside a capillary tube is complex, since flashing process that occurs in case of refrigeration and air-conditioning systems is metastable. A mixture of refrigerants such as nitrogen, methane, ethane, propane and iso-butane expands below its inversion temperature in the capillary tube of MR J-T cryocooler and reaches cryogenic temperature. The mass flow rate of refrigerant mixture circulating through capillary tube depends onmore » the pressure difference across it. There are many empirical correlations which predict pressure drop across the capillary tube. However, they have not been tested for refrigerant mixtures and for operating conditions of the cryocooler. The present paper assesses the existing empirical correlations for predicting overall pressure drop across the capillary tube for the MR J-T cryocooler. The empirical correlations refer to homogeneous as well as separated flow models. Experiments are carried out to measure the overall pressure drop across the capillary tube for the cooler. Three different compositions of refrigerant mixture are used to study the pressure drop variations. The predicted overall pressure drop across the capillary tube is compared with the experimentally obtained value. The predictions obtained using homogeneous model show better match with the experimental results compared to separated flow models.« less

  5. Observation of ice nucleation in acoustically levitated water drops

    NASA Astrophysics Data System (ADS)

    Lü, Y. J.; Xie, W. J.; Wei, B.

    2005-10-01

    The supercooling and nucleation of acoustically levitated water drops were investigated at two different sound pressure levels (SPL). These water drops were supercooled by 13to16K at the low SPL of 160.6dB, whereas their supercoolings varied from 5to11K at the high SPL of 164.4dB. The maximum supercooling obtained in the experiments is 32K. Statistical analyses based on the classical nucleation theory reveal that the occurrence of ice nucleation in water drops is mainly confined to the surface region under acoustic levitation conditions and the enlargement of drop surface area caused by the acoustic radiation pressure reduces water supercoolability remarkably. A comparison of the nucleation rates at the two SPLs indicates that the sound pressure can strengthen the surface-dominated nucleation of water drops. The acoustic stream around levitated water drops and the cavitation effect associated with ultrasonic field are the main factors that induce surface-dominated nucleation.

  6. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface

    PubMed Central

    Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

    2016-01-01

    The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing–most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon’s characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops. PMID:27388276

  7. Sound Wave Energy Resulting from the Impact of Water Drops on the Soil Surface.

    PubMed

    Ryżak, Magdalena; Bieganowski, Andrzej; Korbiel, Tomasz

    2016-01-01

    The splashing of water drops on a soil surface is the first step of water erosion. There have been many investigations into splashing-most are based on recording and analysing images taken with high-speed cameras, or measuring the mass of the soil moved by splashing. Here, we present a new aspect of the splash phenomenon's characterization the measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out for 10 consecutive water drop impacts on the soil surface. Three soils were tested (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa and 16 kPa). We found that the values of the sound pressure and sound wave energy were dependent on the particle size distribution of the soil, less dependent on the initial pressure head, and practically the same for subsequent water drops (from the first to the tenth drop). The highest sound pressure level (and the greatest variability) was for Endogleyic Umbrisol, which had the highest sand fraction content. The sound pressure for this soil increased from 29 dB to 42 dB with the next incidence of drops falling on the sample The smallest (and the lowest variability) was for Fluvic Endogleyic Cambisol which had the highest clay fraction. For all experiments the sound pressure level ranged from ~27 to ~42 dB and the energy emitted in the form of sound waves was within the range of 0.14 μJ to 5.26 μJ. This was from 0.03 to 1.07% of the energy of the incident drops.

  8. Heat Transfer Enhancement Through Self-Sustained Oscillating Flow in Microchannels

    DTIC Science & Technology

    2006-05-01

    Qu and Mudawar [30]. The numerical results for Nusselt number and pressure drop are in good agreement with the experimental Contract Number: FA8650...500 1000 1500 0 0.2 0.4 0.6 0.8 1 Experiment, Qu and Mudawar (2002) Numerical study, present Figure 28. Comparison of pressure drop between numerical...Mass Transfer, 48, 1688-1704, 2005. [30]. Weilin Qu, Issam Mudawar , Experimental and numerical study of pressure drop and heat transfer in a single

  9. O the Electrohydrodynamics of Drop Extraction from a Conductive Liquid Meniscus

    NASA Astrophysics Data System (ADS)

    Wright, Graham Scott

    This thesis is concerned with the use of an electric field in the extraction of liquid drops from a capillary orifice or nozzle. The motivating application is ink jet printing. Current drop-on-demand ink jets use pressure pulses to eject drops. Literature on electrostatic spraying suggests that by using an electric field, drops could be produced with a wider range of sizes and speeds than is possible with pressure ejection. Previous efforts to apply electric spraying to printing or similar selective coating tasks have taken an experimental approach based on steady or periodic spraying phenomena, without attempting cycle -by-cycle drop control. The centerpiece of this thesis is a simulation tool developed to explore such possibilities. A simplified analytic model is developed as a preliminary step, yielding formulas for force and time scales that provide an appropriate basis for nondimensionalization of the governing differential equations; important dimensionless parameters are identified. The complete self-consistent model permits simulation of meniscus behavior under time -varying applied voltage or pressure, with the electric field solution continually updated as the surface changes shape. The model uses a quasi-one-dimensional hydrodynamic formulation and a two-dimensional axisymmetric boundary element solution for the electric field. The simulation is checked against experimental results for meniscus stability, resonant modes, and drop emission under electric field. The simulation faithfully captures important qualitative aspects of meniscus behavior and gives reasonable quantitative agreement within the limitations of the model. Insights gained in simulation point the way to a successful laboratory demonstration of drop extraction using a shaped voltage pulse. Drop size control is pursued in simulation using pressure and voltage pulses both alone and in combination, for both light and viscous liquids. Combining pressure and field pulses is shown to be synergistic; drop volumes over a range of 175 to 1 were obtained, while maintaining good drop velocity. The differing strategies for obtaining large and small drops are described. Drop extraction using only the electric field is more difficult, but promising approaches remain open.

  10. Heat transfer and pressure drop of condensation of hydrocarbons in tubes

    NASA Astrophysics Data System (ADS)

    Fries, Simon; Skusa, Severin; Luke, Andrea

    2018-03-01

    The heat transfer coefficient and pressure drop are investigated for propane. Two different mild steel plain tubes and saturation pressures are considered for varying mass flux and vapour quality. The pressure drop is compared to the Friedel-Correlation with two different approaches to determine the friction factor. The first is calculation as proposed by Friedel and the second is through single phase pressure drop investigations. For lower vapour qualities the experimental results are in better agreement with the approach of the calculated friction factor. For higher vapour qualities the experimental friction factor is more precise. The pressure drop increases for a decreasing tube diameter and saturation pressure. The circumferential temperature profile and heat transfer coefficients are shown for a constant vapour quality at varying mass fluxes. The subcooling is highest for the bottom of the tube and lowest for the top. The average subcooling as well as the circumferential deviation decreases for rising mass fluxes. The averaged heat transfer coefficients are compared to the model proposed by Thome and Cavallini. The experimental results are in good agreement with both correlations, however the trend is better described with the correlation from Thome. The experimental heat transfer coefficients are under predicted by Thome and over predicted by Cavallini.

  11. Negative pressures and spallation in water drops subjected to nanosecond shock waves

    DOE PAGES

    Stan, Claudiu A.; Willmott, Philip R.; Stone, Howard A.; ...

    2016-05-16

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below –100 MPamore » were reached in the drops. As a result, we model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.« less

  12. Analysis on Experimental Investigation and Mathematical Modeling of Incompressible Flow Through Ceramic Foam Filters

    NASA Astrophysics Data System (ADS)

    Akbarnejad, Shahin; Jonsson, Lage Tord Ingemar; Kennedy, Mark William; Aune, Ragnhild Elizabeth; Jönsson, Pӓr Göran

    2016-08-01

    This paper presents experimental results of pressure drop measurements on 30, 50, and 80 pores per inch (PPI) commercial alumina ceramic foam filters (CFF) and compares the obtained pressure drop profiles to numerically modeled values. In addition, it is aimed at investigating the adequacy of the mathematical correlations used in the analytical and the computational fluid dynamics (CFD) simulations. It is shown that the widely used correlations for predicting pressure drop in porous media continuously under-predict the experimentally obtained pressure drop profiles. For analytical predictions, the negative deviations from the experimentally obtained pressure drop using the unmodified Ergun and Dietrich equations could be as high as 95 and 74 pct, respectively. For the CFD predictions, the deviation to experimental results is in the range of 84.3 to 88.5 pct depending on filter PPI. Better results can be achieved by applying the Forchheimer second-order drag term instead of the Brinkman-Forchheimer drag term. Thus, the final deviation of the CFD model estimates lie in the range of 0.3 to 5.5 pct compared to the measured values.

  13. Boiling regimes of impacting drops on a heated substrate under reduced pressure

    NASA Astrophysics Data System (ADS)

    van Limbeek, Michiel A. J.; Hoefnagels, Paul B. J.; Shirota, Minori; Sun, Chao; Lohse, Detlef

    2018-05-01

    We experimentally investigate the boiling behavior of impacting ethanol drops on a heated smooth sapphire substrate at pressures ranging from P =0.13 bar to atmospheric pressure. We employ frustrated total internal reflection imaging to study the wetting dynamics of the contact between the drop and the substrate. The spreading drop can be in full contact (contact boiling), it can partially touch (transition boiling), or the drop can be fully levitated (Leidenfrost boiling). We show that the temperature of the boundary between contact and transition boiling shows at most a weak dependence on the impact velocity, but a significant decrease with decreasing ambient gas pressure. A striking correspondence is found between the temperature of this boundary and the static Leidenfrost temperature for all pressures. We therefore conclude that both phenomena share the same mechanism and are dominated by the dynamics taking place at the contact line. On the other hand, the boundary between transition boiling and Leidenfrost boiling, i.e., the dynamic Leidenfrost temperature, increases for increasing impact velocity for all ambient gas pressures. Moreover, the dynamic Leidenfrost temperature coincides for pressures between P =0.13 and 0.54 bar, whereas for atmospheric pressure the dynamic Leidenfrost temperature is slightly elevated. This indicates that the dynamic Leidenfrost temperature is at most weakly dependent on the enhanced evaporation by the lower saturation temperature of the liquid.

  14. Pressure Profiles in a Loop Heat Pipe Under Gravity Influence

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2015-01-01

    During the operation of a loop heat pipe (LHP), the viscous flow induces pressure drops in various elements of the loop. The total pressure drop is equal to the sum of pressure drops in vapor grooves, vapor line, condenser, liquid line and primary wick, and is sustained by menisci at liquid and vapor interfaces on the outer surface of the primary wick in the evaporator. The menisci will curve naturally so that the resulting capillary pressure matches the total pressure drop. In ground testing, an additional gravitational pressure head may be present and must be included in the total pressure drop when LHP components are placed in a non-planar configuration. Under gravity-neutral and anti-gravity conditions, the fluid circulation in the LHP is driven solely by the capillary force. With gravity assist, however, the flow circulation can be driven by the combination of capillary and gravitational forces, or by the gravitational force alone. For a gravity-assist LHP at a given elevation between the horizontal condenser and evaporator, there exists a threshold heat load below which the LHP operation is gravity driven and above which the LHP operation is capillary force and gravity co-driven. The gravitational pressure head can have profound effects on the LHP operation, and such effects depend on the elevation, evaporator heat load, and condenser sink temperature. This paper presents a theoretical study on LHP operations under gravity neutral, anti-gravity, and gravity-assist modes using pressure diagrams to help understand the underlying physical processes. Effects of the condenser configuration on the gravitational pressure head and LHP operation are also discussed.

  15. Pressure Profiles in a Loop Heat Pipe under Gravity Influence

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2015-01-01

    During the operation of a loop heat pipe (LHP), the viscous flow induces pressure drops in various elements of the loop. The total pressure drop is equal to the sum of pressure drops in vapor grooves, vapor line, condenser, liquid line and primary wick, and is sustained by menisci at liquid and vapor interfaces on the outer surface of the primary wick in the evaporator. The menisci will curve naturally so that the resulting capillary pressure matches the total pressure drop. In ground testing, an additional gravitational pressure head may be present and must be included in the total pressure drop when LHP components are placed in a non-planar configuration. Under gravity-neutral and anti-gravity conditions, the fluid circulation in the LHP is driven solely by the capillary force. With gravity assist, however, the flow circulation can be driven by the combination of capillary and gravitational forces, or by the gravitational force alone. For a gravity-assist LHP at a given elevation between the horizontal condenser and evaporator, there exists a threshold heat load below which the LHP operation is gravity driven and above which the LHP operation is capillary force and gravity co-driven. The gravitational pressure head can have profound effects on the LHP operation, and such effects depend on the elevation, evaporator heat load, and condenser sink temperature. This paper presents a theoretical study on LHP operations under gravity-neutral, anti-gravity, and gravity-assist modes using pressure diagrams to help understand the underlying physical processes. Effects of the condenser configuration on the gravitational pressure head and LHP operation are also discussed.

  16. Aerodynamic effect of combustor inlet-air pressure on fuel jet atomization

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1984-01-01

    Mean drop diameters were measured with a recently developed scanning radiometer in a study of the atomization of liquid jets injected cross stream in high velocity and high pressure airflows. At constant inlet air pressure, reciprocal mean drop diameter, was correlated with airflow mass velocity. Over a combustor inlet-air pressure range of 1 to 21 atmospheres, the ratio of orifice to mean drop diameter, D(O)/D(M), was correlated with the product of Weber and Reynolds number, WeRe, and with the molecular scale momentum transfer ratio of gravitational to inertial forces.

  17. Microgravity combustion of dust suspensions

    NASA Technical Reports Server (NTRS)

    Lee, John H. S.; Peraldi, Olivier; Knystautas, Rom

    1993-01-01

    Unlike the combustion of homogeneous gas mixtures, there are practically no reliable fundamental data (i.e., laminar burning velocity, flammability limits, quenching distance, minimum ignition energy) for the combustion of heterogeneous dust suspensions. Even the equilibrium thermodynamic data such as the constant pressure volume combustion pressure and the constant pressure adiabatic flame temperature are not accurately known for dust mixtures. This is mainly due to the problem of gravity sedimentation. In normal gravity, turbulence, convective flow, electric and acoustic fields are required to maintain a dust in suspension. These external influences have a dominating effect on the combustion processes. Microgravity offers a unique environment where a quiescent dust cloud can in principle be maintained for a sufficiently long duration for almost all combustion experiments (dust suspensions are inherently unstable due to Brownian motion and particle aggregation). Thus, the microgravity duration provided by drop towers, parabolic flights, and the space shuttle, can all be exploited for different kinds of dust combustion experiments. The present paper describes some recent studies on microgravity combustion of dust suspension carried out on the KC-135 and the Caravelle aircraft. The results reported are obtained from three parabolic flight campaigns.

  18. Observed source parameters for dynamic rupture with non-uniform initial stressand relatively high fracture energy

    USGS Publications Warehouse

    Beeler, Nicholas M.; Kilgore, Brian D.; McGarr, Arthur F.; Fletcher, Jon Peter B.; Evans, John R.; Steven R. Baker,

    2012-01-01

    We have conducted dynamic rupture propagation experiments to establish the relations between in-source stress drop, fracture energy and the resulting particle velocity during slip of an unconfined 2 m long laboratory fault at normal stresses between 4 and 8 MPa. To produce high fracture energy in the source we use a rough fault that has a large slip weakening distance. An artifact of the high fracture energy is that the nucleation zone is large such that precursory slip reduces fault strength over a large fraction of the total fault length prior to dynamic rupture, making the initial stress non-uniform. Shear stress, particle velocity, fault slip and acceleration were recorded coseismically at multiple locations along strike and at small fault-normal distances. Stress drop increases weakly with normal stress. Average slip rate depends linearly on the fault strength loss and on static stress drop, both with a nonzero intercept. A minimum fracture energy of 1.8 J/m2 and a linear slip weakening distance of 33 μm are inferred from the intercept. The large slip weakening distance also affects the average slip rate which is reduced by in-source energy dissipation from on-fault fracture energy.Because of the low normal stress and small per event slip (∼86 μm), no thermal weakening such as melting or pore fluid pressurization occurs in these experiments. Despite the relatively high fracture energy, and the very low heat production, energy partitioning during these laboratory earthquakes is very similar to typical earthquake source properties. The product of fracture energy and fault area is larger than the radiated energy. Seismic efficiency is low at ∼2%. The ratio of apparent stress to static stress drop is ∼27%, consistent with measured overshoot. The fracture efficiency is ∼33%. The static and dynamic stress drops when extrapolated to crustal stresses are 2–7.3 MPa and in the range of typical earthquake stress drops. As the relatively high fracture energy reduces the slip velocities in these experiments, the extrapolated average particle velocities for crustal stresses are 0.18–0.6 m/s. That these experiments are consistent with typical earthquake source properties suggests, albeit indirectly, that thermal weakening mechanisms such as thermal pressurization and melting which lead to near complete stress drops, dominate earthquake source properties only for exceptional events unless crustal stresses are low.

  19. Abandoned coal mine stores gas for Colorado peak-day demands

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brown, L.W.

    1978-09-01

    Since 1961, the Leyden Mine, from which 6 million tons of coal had been removed to leave a 150 million cu ft void, has been used for gas storage at 250 psig max pressure, after the hoisting and ventilation shafts had been sealed with concrete, rock, sand, and mud. Following several withdrawal expansions, a design for maximum delivery of 230 million cu ft/day for five days with a pressure drop in the cavern down to 100 psig was developed to satisfy customer requirements for peak shaving. This required redesigning the gathering system by looping large existing lines, eliminating inefficient ones,more » and drilling additional wells; installing three lightweight 3500-hp Centaur turbine/compressor units from Solar Turbines International to provide the minimum 200 psig compressor discharge pressure needed for gas distribution on peak usage days; and installing Donaldson Co. engine air-inlet silencers on the turbine inlets to reduce noise levels below the public code requirement. In the 1977-78 heating season, the Leyden facility produced 196 million cu ft/day of gas; with continued load growth and well drilling to reduce pressure loss, the maximum design flow rate will be attained.« less

  20. Drop dynamics in space and interference with acoustic field (M-15)

    NASA Technical Reports Server (NTRS)

    Yamanaka, Tatsuo

    1993-01-01

    The objective of the experiment is to study contactless positioning of liquid drops, excitation of capillary waves on the surface of acoustically levitated liquid drops, and deformation of liquid drops by means of acoustic radiation pressure. Contactless positioning technologies are very important in space materials processing because the melt is processed without contacting the wall of a crucible which can easily contaminate the melt specifically for high melting temperatures and chemically reactive materials. Among the contactless positioning technologies, an acoustic technology is especially important for materials unsusceptible to electromagnetic fields such as glasses and ceramics. The shape of a levitated liquid drop in the weightless condition is determined by its surface tension and the internal and external pressure distribution. If the surface temperature is constant and there exist neither internal nor external pressure perturbations, the levitated liquid drop forms a shape of perfect sphere. If temperature gradients on the surface and internal or external pressure perturbations exist, the liquid drop forms various modes of shapes with proper vibrations. A rotating liquid drop was specifically studied not only as a classical problem of theoretical mechanics to describe the shapes of the planets of the solar system, as well as their arrangement, but it is also more a contemporary problem of modern non-linear mechanics. In the experiment, we are expecting to observe various shapes of a liquid drop such as cocoon, tri-lobed, tetropod, multi-lobed, and doughnut.

  1. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... distribution systems. (a) No person may operate a low-pressure distribution system at a pressure high enough to...) No person may operate a low pressure distribution system at a pressure lower than the minimum... 49 Transportation 3 2012-10-01 2012-10-01 false Maximum and minimum allowable operating pressure...

  2. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... distribution systems. (a) No person may operate a low-pressure distribution system at a pressure high enough to...) No person may operate a low pressure distribution system at a pressure lower than the minimum... 49 Transportation 3 2011-10-01 2011-10-01 false Maximum and minimum allowable operating pressure...

  3. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... distribution systems. (a) No person may operate a low-pressure distribution system at a pressure high enough to...) No person may operate a low pressure distribution system at a pressure lower than the minimum... 49 Transportation 3 2013-10-01 2013-10-01 false Maximum and minimum allowable operating pressure...

  4. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... distribution systems. (a) No person may operate a low-pressure distribution system at a pressure high enough to...) No person may operate a low pressure distribution system at a pressure lower than the minimum... 49 Transportation 3 2014-10-01 2014-10-01 false Maximum and minimum allowable operating pressure...

  5. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... distribution systems. (a) No person may operate a low-pressure distribution system at a pressure high enough to...) No person may operate a low pressure distribution system at a pressure lower than the minimum... 49 Transportation 3 2010-10-01 2010-10-01 false Maximum and minimum allowable operating pressure...

  6. Study of nitrogen two-phase flow pressure drop in horizontal and vertical orientation

    NASA Astrophysics Data System (ADS)

    Koettig, T.; Kirsch, H.; Santandrea, D.; Bremer, J.

    2017-12-01

    The large-scale liquid argon Short Baseline Neutrino Far-detector located at Fermilab is designed to detect neutrinos allowing research in the field of neutrino oscillations. It will be filled with liquid argon and operate at almost ambient pressure. Consequently, its operation temperature is determined at about 87 K. The detector will be surrounded by a thermal shield, which is actively cooled with boiling nitrogen at a pressure of about 2.8 bar absolute, the respective saturation pressure of nitrogen. Due to strict temperature gradient constraints, it is important to study the two-phase flow pressure drop of nitrogen along the cooling circuit of the thermal shield in different orientations of the flow with respect to gravity. An experimental setup has been built in order to determine the two-phase flow pressure drop in nitrogen in horizontal, vertical upward and vertical downward direction. The measurements have been conducted under quasi-adiabatic conditions and at a saturation pressure of 2.8 bar absolute. The mass velocity has been varied in the range of 20 kg·m-2·s-1 to 70 kg·m-2·s-1 and the pressure drop data has been recorded scanning the two-phase region from vapor qualities close to zero up to 0.7. The experimental data will be compared with several established predictions of pressure drop e.g. Mueller-Steinhagen and Heck by using the void fraction correlation of Rouhani.

  7. Experimental and Computational Study of the Hydrodynamics of Trickle Bed Flow Reactor Operating Under Different Pressure Conditions

    NASA Astrophysics Data System (ADS)

    Rabbani, S.; Ben Salem, I.; Nadeem, H.; Kurnia, J. C.; Shamim, T.; Sassi, M.

    2014-12-01

    Pressure drop estimation and prediction of liquid holdup play a crucial role in design and operation of trickle bed reactors. Experiments are performed for Light Gas Oil (LGO)-nitrogen system in ambient temperature conditions in an industrial pilot plant with reactor height 0.79 m and diameter of 0.0183 m and pressure ranging from atmospheric to 10 bars. It was found that pressure drop increased with increase in system pressure, superficial gas velocity and superficial liquid velocity. It was demonstrated in the experiments that liquid holdup of the system increases with the increase in superficial liquid velocity and tends to decrease with increase in superficial gas velocity which is in good agreement with existing literature. Similar conditions were also simulated using CFD-software FLUENT. The Volume of Fluid (VoF) technique was employed in combination with "discrete particle approach" and results were compared with that of experiments. The overall pressure drop results were compared with the different available models and a new comprehensive model was proposed to predict the pressure drop in Trickle Bed Flow Reactor.

  8. Reducing cyclone pressure drop with evasés

    USDA-ARS?s Scientific Manuscript database

    Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection...

  9. Determination of pressure drop across activated carbon fiber respirator cartridges.

    PubMed

    Balanay, Jo Anne G; Lungu, Claudiu T

    2016-01-01

    Activated carbon fiber (ACF) is considered as an alternative adsorbent to granular activated carbon (GAC) for the development of thinner, lighter, and efficient respirators because of their larger surface area and adsorption capacities, thinner critical bed depth, lighter weight, and fabric form. This study aims to measure the pressure drop across different types of commercially available ACFs in respirator cartridges to determine the ACF composition and density that will result in acceptably breathable respirators. Seven ACF types in cloth (ACFC) and felt (ACFF) forms were tested. ACFs in cartridges were challenged with pre-conditioned constant air flow (43 LPM, 23°C, 50% RH) at different compositions (single- or combination-ACF type) in a test chamber. Pressure drop across ACF cartridges were obtained using a micromanometer, and compared among different cartridge configurations, to those of the GAC cartridge, and to the NIOSH breathing resistance requirements for respirator cartridges. Single-ACF type cartridges filled with any ACFF had pressure drop measurements (23.71-39.93 mmH2O) within the NIOSH inhalation resistance requirement of 40 mmH2O, while those of the ACFC cartridges (85.47±3.67 mmH2O) exceeded twice the limit due possibly to the denser weaving of ACFC fibers. All single ACFF-type cartridges had higher pressure drop compared to the GAC cartridge (23.13±1.14 mmH2O). Certain ACF combinations (2 ACFF or ACFC/ACFF types) resulted to pressure drop (26.39-32.81 mmH2O) below the NIOSH limit. All single-ACFF type and all combination-ACF type cartridges with acceptable pressure drop had much lower adsorbent weights than GAC (≤15.2% of GAC weight), showing potential for light-weight respirator cartridges. 100% ACFC in cartridges may result to respirators with high breathing resistance and, thus, is not recommended. The more dense ACFF and ACFC types may still be possibly used in respirators by combining them with less dense ACFF materials and/or by reducing cartridge bed depth to reduce pressure drop to acceptable levels. ACFF by itself may be more appropriate as adsorbent materials in ACF respirator cartridges in terms of acceptable breathing resistance.

  10. The Minimum Grading Controversy: Results of a Quantitative Study of Seven Years of Grading Data from an Urban High School

    ERIC Educational Resources Information Center

    Carey, Theodore; Carifio, James

    2012-01-01

    In an effort to reduce failure and drop-out rates, schools have been implementing minimum grading. One form involves raising catastrophically low student quarter grades to a predetermined minimum--typically a 50. Proponents argue it gives struggling students a reasonable chance to recover from failure. Critics contend the practice induces grade…

  11. Digibaro pressure instrument onboard the Phoenix Lander

    NASA Astrophysics Data System (ADS)

    Harri, A.-M.; Polkko, J.; Kahanpää, H. H.; Schmidt, W.; Genzer, M. M.; Haukka, H.; Savijarv1, H.; Kauhanen, J.

    2009-04-01

    The Phoenix Lander landed successfully on the Martian northern polar region. The mission is part of the National Aeronautics and Space Administration's (NASA's) Scout program. Pressure observations onboard the Phoenix lander were performed by an FMI (Finnish Meteorological Institute) instrument, based on a silicon diaphragm sensor head manufactured by Vaisala Inc., combined with MDA data processing electronics. The pressure instrument performed successfully throughout the Phoenix mission. The pressure instrument had 3 pressure sensor heads. One of these was the primary sensor head and the other two were used for monitoring the condition of the primary sensor head during the mission. During the mission the primary sensor was read with a sampling interval of 2 s and the other two were read less frequently as a check of instrument health. The pressure sensor system had a real-time data-processing and calibration algorithm that allowed the removal of temperature dependent calibration effects. In the same manner as the temperature sensor, a total of 256 data records (8.53 min) were buffered and they could either be stored at full resolution, or processed to provide mean, standard deviation, maximum and minimum values for storage on the Phoenix Lander's Meteorological (MET) unit.The time constant was approximately 3s due to locational constraints and dust filtering requirements. Using algorithms compensating for the time constant effect the temporal resolution was good enough to detect pressure drops associated with the passage of nearby dust devils.

  12. 40 CFR 63.1657 - Monitoring requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... pressure drop across each baghouse cell, or across the baghouse if it is not possible to monitor each cell individually, to ensure the pressure drop is within the normal operating range identified in the baghouse... detection system if the furnace primary and/or tapping emissions are ducted to a negative pressure baghouse...

  13. Improving the efficiency of an Er:YAG laser on enamel and dentin.

    PubMed

    Rizcalla, Nicolas; Bader, Carl; Bortolotto, Tissiana; Krejci, Ivo

    2012-02-01

    To evaluate the influence of air pressure, water flow rate, and pulse frequency on the removal speed of enamel and dentin as well as on their surface morphology. Twenty-four bovine incisors were horizontally cut in slices. Each sample was mounted on an experimental assembly, allowing precise orientation. Eighteen cavities were prepared, nine in enamel and nine in dentin. Specific parameters for frequency, water flow rate, and air pressure were applied for each experimental group. Three groups were randomly formed according to the air pressure settings. Cavity depth was measured using a digital micrometer gauge, and surface morphology was checked by means of scanning electron microscopy. Data was analyzed with ANOVA and Duncan post hoc test. Irradiation at 25 Hz for enamel and 30 Hz for dentin provided the best ablation rates within this study, but efficiency decreased if the frequency was raised further. Greater tissue ablation was found with water flow rate set to low and dropped with higher values. Air pressure was found to have an interaction with the other settings, since ablation rates varied with different air pressure values. Fine-tuning of all parameters to get a good ablation rate with minimum surface damage seems to be key in achieving optimal efficiency for cavity preparation with an Er:YAG laser.

  14. Heat transfer and pressure drop performance of a finned-tube heat exchanger proposed for use in the NASA Lewis Altitude Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Vanfossen, G. J.

    1985-01-01

    A segment of the heat exchanger proposed for use in the NASA Lewis Altitude Wind Tunnel (AWT) facility has been tested under dry and icing conditions. The heat exchanger has the largest pressure drop of any component in the AWT loop. It is therefore critical that its performance be known at all conditions before the final design of the AWT is complete. The heat exchanger segment is tested in the NASA Lewis Icing Research Tunnel (IRT) in order to provide an icing cloud environment similar to what will be encountered in the AWT. Dry heat transfer and pressure drop data are obtained and compared to correlations available in the literature. The effects of icing sprays on heat transfer and pressure drop are also investigated.

  15. Variability among electronic cigarettes in the pressure drop, airflow rate, and aerosol production.

    PubMed

    Williams, Monique; Talbot, Prue

    2011-12-01

    This study investigated the performance of electronic cigarettes (e-cigarettes), compared different models within a brand, compared identical copies of the same model within a brand, and examined performance using different protocols. Airflow rate required to generate aerosol, pressure drop across e-cigarettes, and aerosol density were examined using three different protocols. First 10 puff protocol: The airflow rate required to produce aerosol and aerosol density varied among brands, while pressure drop varied among brands and between the same model within a brand. Total air hole area correlated with pressure drop for some brands. Smoke-out protocol: E-cigarettes within a brand generally performed similarly when puffed to exhaustion; however, there was considerable variation between brands in pressure drop, airflow rate required to produce aerosol, and the total number of puffs produced. With this protocol, aerosol density varied significantly between puffs and gradually declined. CONSECUTIVE TRIAL PROTOCOL: Two copies of one model were subjected to 11 puffs in three consecutive trials with breaks between trials. One copy performed similarly in each trial, while the second copy of the same model produced little aerosol during the third trial. The different performance properties of the two units were attributed to the atomizers. There was significant variability between and within brands in the airflow rate required to produce aerosol, pressure drop, length of time cartridges lasted, and production of aerosol. Variation in performance properties within brands suggests a need for better quality control during e-cigarette manufacture.

  16. Experimental investigation of ice slurry flow pressure drop in horizontal tubes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Grozdek, Marino; Khodabandeh, Rahmatollah; Lundqvist, Per

    2009-01-15

    Pressure drop behaviour of ice slurry based on ethanol-water mixture in circular horizontal tubes has been experimentally investigated. The secondary fluid was prepared by mixing ethyl alcohol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature -4.4 C). The pressure drop tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 30% depending on test conditions. Results from flow tests reveal much higher pressure drop for higher ice concentrations and higher velocities in comparison to the single phase flow. However for ice concentrations of 15% and higher, certain velocitymore » exists at which ice slurry pressure drop is same or even lower than for single phase flow. It seems that higher ice concentration delay flow pattern transition moment (from laminar to turbulent) toward higher velocities. In addition experimental results for pressure drop were compared to the analytical results, based on Poiseulle and Buckingham-Reiner models for laminar flow, Blasius, Darby and Melson, Dodge and Metzner, Steffe and Tomita for turbulent region and general correlation of Kitanovski which is valid for both flow regimes. For laminar flow and low buoyancy numbers Buckingham-Reiner method gives good agreement with experimental results while for turbulent flow best fit is provided with Dodge-Metzner and Tomita methods. Furthermore, for transport purposes it has been shown that ice mass fraction of 20% offers best ratio of ice slurry transport capability and required pumping power. (author)« less

  17. Experimental Investigation of Two-Phase Oil (D130)-Water Flow in 4″ Pipe for Different Inclination Angles

    NASA Astrophysics Data System (ADS)

    Shaahid, S. M.; Basha, Mehaboob; Al-Hems, Luai M.

    2018-03-01

    Oil and water are often produced and transported together in pipelines that have various degrees of inclination from the horizontal. The flow of two immiscible liquids oil and water in pipes has been a research topic since several decades. In oil and chemical industries, knowledge of the frictional pressure loss in oil-water flows in pipes is necessary to specify the size of the pump required to pump the emulsions. An experimental investigation has been carried out for measurement of pressure drop of oil (D130)-water two-phase flows in 4 inch diameter inclined stainless steel pipe at different flow conditions. Experiments were conducted for different inclination angles including; 0°, 15°, 30° (for water cuts “WC” 0 - 100%). The flow rates at the inlet were varied from 4000 to 8000 barrels-per-day (BPD). For a given flow rate the frictional pressure drop has been found to increase (for all angles) from WC = 0 - 60%, and thereafter friction pressure drop decreases, this could be due phase inversion. For a given WC 40%, the frictional pressure drop has been found to increase with angle and flow rate. It has been noticed that inclination angle has appreciable effect on frictional pressure drop.

  18. Aerodynamic effect of combustor inlet-air pressure on fuel jet atomization

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1984-01-01

    Mean drop diameters were measured with a recently developed scanning radiometer in a study of the atomization of liquid jets injected cross stream in high velocity and high pressure airflows. At constant inlet air pressure, reciprocal mean drop diameter was correlated with airflow mass velocity. Over a combustor inlet-air pressure range of 1 to 21 atmospheres, the ratio of orifice to mean drop diameter, D(O)/D(M), was correlated with the product of Weber and Reynolds number, WeRe, and with the molecular scale momentum transfer ratio of gravitational to inertial forces. Previously announced in STAR as N84-22910

  19. The respective effect of under-rib convection and pressure drop of flow fields on the performance of PEM fuel cells.

    PubMed

    Wang, Chao; Zhang, Qinglei; Shen, Shuiyun; Yan, Xiaohui; Zhu, Fengjuan; Cheng, Xiaojing; Zhang, Junliang

    2017-03-02

    The flow field configuration plays an important role on the performance of proton exchange membrane fuel cells (PEMFCs). For instance, channel/rib width and total channel cross-sectional area determine the under-rib convection and pressure drop respectively, both of which directly influence the water removal, in turn affecting the oxygen supply and cathodic oxygen reduction reaction. In this study, effects of under-rib convection and pressure drop on cell performance are investigated experimentally and numerically by adjusting the channel/rib width and channel cross-sectional area of flow fields. The results show that the performance differences with various flow field configurations mainly derive from the oxygen transport resistance which is determined by the water accumulation degree, and the cell performance would benefit from the narrower channels and smaller cross sections. It reveals that at low current densities when water starts to accumulate in GDL at under-rib regions, the under-rib convection plays a more important role in water removal than pressure drop does; in contrast, at high current densities when water starts to accumulate in channels, the pressure drop dominates the water removal to facilitate the oxygen transport to the catalyst layer.

  20. The respective effect of under-rib convection and pressure drop of flow fields on the performance of PEM fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Zhang, Qinglei; Shen, Shuiyun; Yan, Xiaohui; Zhu, Fengjuan; Cheng, Xiaojing; Zhang, Junliang

    2017-03-01

    The flow field configuration plays an important role on the performance of proton exchange membrane fuel cells (PEMFCs). For instance, channel/rib width and total channel cross-sectional area determine the under-rib convection and pressure drop respectively, both of which directly influence the water removal, in turn affecting the oxygen supply and cathodic oxygen reduction reaction. In this study, effects of under-rib convection and pressure drop on cell performance are investigated experimentally and numerically by adjusting the channel/rib width and channel cross-sectional area of flow fields. The results show that the performance differences with various flow field configurations mainly derive from the oxygen transport resistance which is determined by the water accumulation degree, and the cell performance would benefit from the narrower channels and smaller cross sections. It reveals that at low current densities when water starts to accumulate in GDL at under-rib regions, the under-rib convection plays a more important role in water removal than pressure drop does; in contrast, at high current densities when water starts to accumulate in channels, the pressure drop dominates the water removal to facilitate the oxygen transport to the catalyst layer.

  1. Development of a primary standard for dynamic pressure based on drop weight method covering a range of 10 MPa-400 MPa

    NASA Astrophysics Data System (ADS)

    Salminen, J.; Högström, R.; Saxholm, S.; Lakka, A.; Riski, K.; Heinonen, M.

    2018-04-01

    In this paper we present the development of a primary standard for dynamic pressures that is based on the drop weight method. At the moment dynamic pressure transducers are typically calibrated using reference transducers, which are calibrated against static pressure standards. Because dynamic and static characteristics of pressure transducers may significantly differ from each other, it is important that these transducers are calibrated against dynamic pressure standards. In a method developed in VTT Technical Research Centre of Finland Ltd, Centre for Metrology MIKES, a pressure pulse is generated by impact between a dropping weight and a piston of a liquid-filled piston-cylinder assembly. The traceability to SI-units is realized through interferometric measurement of the acceleration of the dropping weight during impact, the effective area of the piston-cylinder assembly and the mass of the weight. Based on experimental validation and an uncertainty evaluation, the developed primary standard provides traceability for peak pressures in the range from 10 MPa to 400 MPa with a few millisecond pulse width and a typical relative expanded uncertainty (k  =  2) of 1.5%. The performance of the primary standard is demonstrated by test calibrations of two dynamic pressure transducers.

  2. Influence of ambient air pressure on effervescent atomization

    NASA Technical Reports Server (NTRS)

    Chen, S. K.; Lefebvre, A. H.; Rollbuhler, J.

    1993-01-01

    The influence of ambient air pressure on the drop-size distributions produced in effervescent atomization is examined in this article. Also investigated are the effects on spray characteristics of variations in air/liquid mass ratio, liquid-injection pressure, and atomizer discharge-orifice diameter at different levels of ambient air pressure. It is found that continuous increase in air pressure above the normal atmospheric value causes the mean drop-size to first increase up to a maximum value and then decline. An explanation for this characteristic is provided in terms of the various contributing factors to the overall atomization process. It is also observed that changes in atomizer geometry and operating conditions have little effect on the distribution of drop-sizes in the spray.

  3. Carbonate formation on Mars: Latest experiments

    NASA Technical Reports Server (NTRS)

    Stephens, S. K.; Stevenson, D. J.; Rossman, G. R.; Keyser, L. F.

    1993-01-01

    Laboratory simulations of Martian CO2 storage address whether carbonate formation could have reduced CO2 pressure from a hypothetical greater than 1 bar to the present 7 mbar in less than or equal to 3 to 4 billion years. This problem is addressed with experiments and analysis designed to verify and improve previous kinetic measurements, reaction mechanisms, and product characterizations, with the goal of improving existing models of Martian CO2 history. A sensitive manometer monitored the pressure drop of CO2 due to uptake by powdered silicate for periods of 3 to 100+ days. Pressure drops for diopside 1 and basalt show rapid short-term (approximately one day) CO2 uptake and considerably slower long-term pressure drops. Curves for diopside 2, olivine 1, and olivine 2 are qualitatively similar to those for diopside 1, whereas quartz and plagioclase show near-zero short-term pressure drops and very slow long-term signals, indistinguishable from a leak (less than 10(exp 11) mol/sq m/s).

  4. Prediction of friction pressure drop for low pressure two-phase flows on the basis of approximate analytical models

    NASA Astrophysics Data System (ADS)

    Zubov, N. O.; Kaban'kov, O. N.; Yagov, V. V.; Sukomel, L. A.

    2017-12-01

    Wide use of natural circulation loops operating at low redused pressures generates the real need to develop reliable methods for predicting flow regimes and friction pressure drop for two-phase flows in this region of parameters. Although water-air flows at close-to-atmospheric pressures are the most widely studied subject in the field of two-phase hydrodynamics, the problem of reliably calculating friction pressure drop can hardly be regarded to have been fully solved. The specific volumes of liquid differ very much from those of steam (gas) under such conditions, due to which even a small change in flow quality may cause the flow pattern to alter very significantly. Frequently made attempts to use some or another universal approach to calculating friction pressure drop in a wide range of steam quality values do not seem to be justified and yield predicted values that are poorly consistent with experimentally measured data. The article analyzes the existing methods used to calculate friction pressure drop for two-phase flows at low pressures by comparing their results with the experimentally obtained data. The advisability of elaborating calculation procedures for determining the friction pressure drop and void fraction for two-phase flows taking their pattern (flow regime) into account is demonstrated. It is shown that, for flows characterized by low reduced pressures, satisfactory results are obtained from using a homogeneous model for quasi-homogeneous flows, whereas satisfactory results are obtained from using an annular flow model for flows characterized by high values of void fraction. Recommendations for making a shift from one model to another in carrying out engineering calculations are formulated and tested. By using the modified annular flow model, it is possible to obtain reliable predictions for not only the pressure gradient but also for the liquid film thickness; the consideration of droplet entrainment and deposition phenomena allows reasonable corrections to be introduced into calculations. To the best of the authors' knowledge, it is for the first time that the entrainment of droplets from the film surface is taken into consideration in the dispersed-annular flow model.

  5. Microseismicity Induced by Fluid Pressure Drop (Laboratory Study)

    NASA Astrophysics Data System (ADS)

    Turuntaev, Sergey; Zenchenko, Evgeny; Melchaeva, Olga

    2013-04-01

    Pore pressure change in saturated porous rocks may result in its fracturing (Maury et Fourmaintraux, 1993) and corresponding microseismic event occurrences. Microseismicity due to fluid injection is considered in numerous papers (Maxwell, 2010, Shapiro et al., 2005). Another type of the porous medium fracturing is related with rapid pore pressure drop at some boundary. The mechanism of such fracturing was considered by (Khristianovich, 1985) as a model of sudden coal blowing and by (Alidibirov, Panov, 1998) as a model of volcano eruptions. If the porous saturated medium has a boundary where it directly contacted with fluid under the high pressure (in a hydraulic fracture or in a borehole), and the pressure at that boundary is dropped, the conditions for tensile cracks can be achieved at some distance from the boundary. In the paper, the results of experimental study of saturated porous sample fracturing due to pore pressure rapid drop are discussed. The samples (82 mm high, ∅60 mm) were made of quartz sand, which was cemented by "liquid glass" glue with mass fraction 1%. The sample (porosity 35%, uniaxial unconfined compression strength 2.5 MPa) was placed in a mould and saturated by oil. The upper end of the sample contacted with the mould upper lid, the lower end contacted with fluid. The fluid pressure was increased to 10 MPa and then discharged through the bottom nipple. The pressure increases/drops were repeated 30-50 times. Pore pressure and acoustic emission (AE) were registered by transducers mounted into upper and bottom lids of the mould. It was found, that AE sources (corresponded to microfracturing) were spreading from the open end to the closed end of the sample, and that maximal number of AE events was registered at some distance from the opened end. The number of AE pulses increased with every next pressure drop, meanwhile the number of pulses with high amplitudes diminished. It was found that AE maximal rate corresponded to the fluid pressure gradient maximal values. The model of AE relation with the pore pressure gradient was considered based on the following assumptions: AE event occurred when the pore pressure gradient reaches some critical value; the critical value varies and can be described by Weibull distribution. Permeability variation during the fluid pressure drop was estimated by means of fluid pressure data and pore-elastic equation solution for small time intervals (0.01 sec). The study showed possibility to solve both a direct problem of microseismicity variation relation with fluid pressure changes and an inverse problem of defining permeability by registering microseismic activity variation in particular volume of porous medium alongside with pore pressure measurements at some point.

  6. Boiling characteristics of dilute polymer solutions and implications for the suppression of vapor explosions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bang, K.H.; Kim, M.H.

    Quenching experiments of hot solid spheres in dilute aqueous solutions of polyethylene oxide polymer have been conducted for the purpose of investigating the physical mechanisms of the suppression of vapor explosions in this polymer solutions. Two spheres of 22.2mm and 9.5mm-diameter were tested in the polymer solutions of various concentrations at 30{degrees}C. Minimum film boiling temperature ({Delta}T{sub MFB}) in this highly-subcooled liquid rapidly decreased from over 700{degrees}c for pure water to about 150{degrees}C as the polymer concentration was increased up to 300ppm for 22.2mm sphere, and it decreased to 350{degrees}C for 9.5mm sphere. This rapid reduction of minimum film boilingmore » temperature in the PEO aqueous solutions can explain its ability of the suppression of spontaneous vapor explosions. The ability of suppression of vapor explosions by dilute polyethylene oxide solutions against an external trigger pressure was tested by dropping molten tin into the polymer solutions at 25{degrees}C. It was observed that in 50ppm solutions more mass fragmented than in pure water, but produced weaker explosion pressures. The explosion was completely suppressed in 300ppm solutions with the external trigger. The debris size distributions of fine fragments smaller than 0.7mm were shown almost identical regardless of the polymer concentrations.« less

  7. Could some aviation deep vein thrombosis be a form of decompression sickness?

    PubMed

    Buzzacott, Peter; Mollerlokken, Andreas

    2016-10-01

    Aviation deep vein thrombosis is a challenge poorly understood in modern aviation. The aim of the present project was to determine if cabin decompression might favor formation of vascular bubbles in commercial air travelers. Thirty commercial flights were taken. Cabin pressure was noted at take-off and at every minute following, until the pressure stabilized. These time-pressure profiles were imported into the statistics program R and analyzed using the package SCUBA. Greatest pressure differentials between tissues and cabin pressures were estimated for 20, 40, 60, 80 and 120 min half-time compartments. Time to decompress ranged from 11 to 47 min. The greatest drop in cabin pressure was from 1022 to 776 mBar, equivalent to a saturated diver ascending from 2.46 msw depth. Mean pressure drop in flights >2 h duration was 193 mBar, while mean pressure drop in flights <2 h was 165 mBar. The greatest drop in pressure over 1 min was 28 mBar. Over 30 commercial flights it was found that the drop in cabin pressure was commensurate with that found to cause bubbles in man. Both the US Navy and the Royal Navy mandate far slower decompression from states of saturation, being 1.7 and 1.9 mBar/min respectively. The median overall rate of decompression found in this study was 8.5 mBar/min, five times the rate prescribed for USN saturation divers. The tissues associated with hypobaric bubble formation are likely slower than those associated with bounce diving, with 60 min a potentially useful index.

  8. Alterations of Blood Flow Through Arteries Following Atherectomy and the Impact on Pressure Variation and Velocity.

    PubMed

    Plourde, Brian D; Vallez, Lauren J; Sun, Biyuan; Nelson-Cheeseman, Brittany B; Abraham, John P; Staniloae, Cezar S

    2016-09-01

    Simulations were made of the pressure and velocity fields throughout an artery before and after removal of plaque using orbital atherectomy plus adjunctive balloon angioplasty or stenting. The calculations were carried out with an unsteady computational fluid dynamic solver that allows the fluid to naturally transition to turbulence. The results of the atherectomy procedure leads to an increased flow through the stenotic zone with a coincident decrease in pressure drop across the stenosis. The measured effect of atherectomy and adjunctive treatment showed decrease the systolic pressure drop by a factor of 2.3. Waveforms obtained from a measurements were input into a numerical simulation of blood flow through geometry obtained from medical imaging. From the numerical simulations, a detailed investigation of the sources of pressure loss was obtained. It is found that the major sources of pressure drop are related to the acceleration of blood through heavily occluded cross sections and the imperfect flow recovery downstream. This finding suggests that targeting only the most occluded parts of a stenosis would benefit the hemodynamics. The calculated change in systolic pressure drop through the lesion was a factor of 2.4, in excellent agreement with the measured improvement. The systolic and cardiac-cycle-average pressure results were compared with measurements made in a multi-patient study treated with orbital atherectomy and adjunctive treatment. The agreements between the measured and calculated systolic pressure drop before and after the treatment were within 3%. This excellent agreement adds further confidence to the results. This research demonstrates the use of orbital atherectomy to facilitate balloon expansion to restore blood flow and how pressure measurements can be utilized to optimize revascularization of occluded peripheral vessels.

  9. A fault constitutive relation accounting for thermal pressurization of pore fluid

    USGS Publications Warehouse

    Andrews, D.J.

    2002-01-01

    The heat generated in a slip zone during an earthquake can raise fluid pressure and thereby reduce frictional resistance to slip. The amount of fluid pressure rise depends on the associated fluid flow. The heat generated at a given time produces fluid pressure that decreases inversely with the square root of hydraulic diffusivity times the elapsed time. If the slip velocity function is crack-like, there is a prompt fluid pressure rise at the onset of slip, followed by a slower increase. The stress drop associated with the prompt fluid pressure rise increases with rupture propagation distance. The threshold propagation distance at which thermally induced stress drop starts to dominate over frictionally induced stress drop is proportional to hydraulic diffusivity. If hydraulic diffusivity is 0.02 m2/s, estimated from borehole samples of fault zone material, the threshold propagation distance is 300 m. The stress wave in an earthquake will induce an unknown amount of dilatancy and will increase hydraulic diffusivity, both of which will lessen the fluid pressure effect. Nevertheless, if hydraulic diffusivity is no more than two orders of magnitude larger than the laboratory value, then stress drop is complete in large earthquakes.

  10. Thermally driven oscillations and wave motion of a liquid drop

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Hendricks, R. C.; Schoessow, G. J.

    1977-01-01

    In the state of Leidenfrost boiling, liquid drops are observed to vibrate in a variety of modal patterns. Theories are presented which predict the frequency of oscillation and show that the observed modal patterns of drops correspond to the minimum energy oscillatory excitation state. High-speed photographic techniques were used to record these motions and substantiate the theories. An incipient temperature was also found for water drops in film boiling below which free oscillations do not exist. In addition to these oscillations, photographic sequences are presented which show that wave motion can exist along the circumference of the drop. Following the study of free oscillations, the system was mounted on a shaker table and the drop subjected to a range of forced frequencies and accelerations.

  11. Thermally Driven Oscillations and Wave Motion of a Liquid Drop

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Hendricks, R. C.; Schoessow, G. J.

    1977-01-01

    In the state of Leidenfrost boiling, liquid drops are observed to vibrate in a variety of modal patterns. Theories are presented which predict the frequency of oscillation and show that the observed model patterns of drops correspond to the minimum energy oscillatory excitation state. High-speed photographic techniques were used to record these motions and substantiate the theories. An incipient temperature was also found for water drops in film boiling below which free oscillations do not exist. In addition to these oscillations, photographic sequences are presented which show that wave motion can exist along the circumference of the drop. Following the study of free oscillations, the system was mounted on a shaker table and the drop subjected to a range of forced frequencies and accelerations.

  12. Soft Listeria: actin-based propulsion of liquid drops.

    PubMed

    Boukellal, Hakim; Campás, Otger; Joanny, Jean-François; Prost, Jacques; Sykes, Cécile

    2004-06-01

    We study the motion of oil drops propelled by actin polymerization in cell extracts. Drops deform and acquire a pearlike shape under the action of the elastic stresses exerted by the actin comet, a tail of cross-linked actin filaments. We solve this free boundary problem and calculate the drop shape taking into account the elasticity of the actin gel and the variation of the polymerization velocity with normal stress. The pressure balance on the liquid drop imposes a zero propulsive force if gradients in surface tension or internal pressure are not taken into account. Quantitative parameters of actin polymerization are obtained by fitting theory to experiment.

  13. Meteorological effects of the solar eclipse of 20 March 2015: analysis of UK Met Office automatic weather station data and comparison with automatic weather station data from the Faroes and Iceland

    PubMed Central

    Penman, John; Jónsson, Trausti; Bigg, Grant R.; Björnsson, Halldór; Sjúrðarson, Sølvi; Hansen, Mads A.; Cappelen, John; Bryant, Robert G.

    2016-01-01

    Here, we analyse high-frequency (1 min) surface air temperature, mean sea-level pressure (MSLP), wind speed and direction and cloud-cover data acquired during the solar eclipse of 20 March 2015 from 76 UK Met Office weather stations, and compare the results with those from 30 weather stations in the Faroe Islands and 148 stations in Iceland. There was a statistically significant mean UK temperature drop of 0.83±0.63°C, which occurred over 39 min on average, and the minimum temperature lagged the peak of the eclipse by about 10 min. For a subset of 14 (16) relatively clear (cloudy) stations, the mean temperature drop was 0.91±0.78 (0.31±0.40)°C but the mean temperature drops for relatively calm and windy stations were almost identical. Mean wind speed dropped significantly by 9% on average during the first half of the eclipse. There was no discernible effect of the eclipse on the wind-direction or MSLP time series, and therefore we can discount any localized eclipse cyclone effect over Britain during this event. Similar changes in air temperature and wind speed are observed for Iceland, where conditions were generally clearer, but here too there was no evidence of an eclipse cyclone; in the Faroes, there was a much more muted meteorological signature. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’. PMID:27550769

  14. Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

    NASA Technical Reports Server (NTRS)

    Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

  15. Pumping power considerations in the designs of NASA-Redox flow cells

    NASA Technical Reports Server (NTRS)

    Hoberecht, M. A.

    1981-01-01

    Pressure drop data for six different cell geometries of various flow port, manifold, and cavity dimensions are presented. The redox/energy/storage system uses two fully soluble redox couples as anode and cathode fluids. Both fluids are pumped through a redox cell, or stack of cells, where the electrochemical reactions take place at porous carbon felt electrodes. Pressure drop losses are therefore associated with this system due to the continuous flow of reactant solutions. The exact pressure drop within a redox flow cell is directly dependent on the flow rate as well as the various cell dimensions. Pumping power requirements for a specific set of cell operating conditions are found for various cell geometries once the flow rate and pressure drop are determined. These pumping power requirements contribute to the overall system parasitic energy losses which must be minimized, the choice of cell geometry becomes critical.

  16. The critical pressure drop for the purge process in the anode of a fuel cell

    NASA Astrophysics Data System (ADS)

    Yu, Xiao; Pingwen, Ming; Ming, Hou; Baolian, Yi; Shao, Zhi-Gang

    Purge operation is an effective way to remove the accumulated liquid water in the anode of proton exchange membrane fuel cells (PEMFCs). This paper studies the phenomenon of the two-phase flow as well as the pressure drop fluctuation inside the flow field of a single cell during the purge process. The flow patterns are identified as intermittent purge and annular purge, and the two purge processes are contrastively analyzed and discussed. The intermittent purge greatly affects the fuel cell performance and thus it is not suitable for the in situ application. The annular purge process requires a higher pressure drop, and the critical pressure drop is calculated from the annular purge model. Furthermore, this value is quantitatively analyzed and validated by experiments. The results show that the annular purge is appropriate for removing liquid water out of the anode in the fuel cell.

  17. Effect of superficial velocity on vaporization pressure drop with propane in horizontal circular tube

    NASA Astrophysics Data System (ADS)

    Novianto, S.; Pamitran, A. S.; Nasruddin, Alhamid, M. I.

    2016-06-01

    Due to its friendly effect on the environment, natural refrigerants could be the best alternative refrigerant to replace conventional refrigerants. The present study was devoted to the effect of superficial velocity on vaporization pressure drop with propane in a horizontal circular tube with an inner diameter of 7.6 mm. The experiments were conditioned with 4 to 10 °C for saturation temperature, 9 to 20 kW/m2 for heat flux, and 250 to 380 kg/m2s for mass flux. It is shown here that increased heat flux may result in increasing vapor superficial velocity, and then increasing pressure drop. The present experimental results were evaluated with some existing correlations of pressure drop. The best prediction was evaluated by Lockhart-Martinelli (1949) with MARD 25.7%. In order to observe the experimental flow pattern, the present results were also mapped on the Wang flow pattern map.

  18. Pressure at the ground in a large tornado

    NASA Astrophysics Data System (ADS)

    Winn, W. P.; Hunyady, S. J.; Aulich, G. D.

    1999-09-01

    A number of instruments were placed on the ground across the path of a large tornado that passed west of the town of Allison, Texas, on June 8, 1995. The center of the tornado came within 660 m of the closest instrument, which recorded a pressure drop of 55 mbar and a subsequent pressure rise of 60 mbar. During the lowest recorded pressures (near r = 660 m), there were large and rapid pressure fluctuations; the largest fluctuation was a 10-mbar spike lasting 2 s. A second instrument on the opposite side of the tornado recorded a pressure drop of 26 mbar. From the pressure variations with time P(t) at the two instruments, the variation of pressure with distance p(r) from the center of the tornado has been deduced for r>660 m. As r decreases, the measured pressure function p(r) drops more abruptly than would be expected from conservation of angular momentum of air spiraling inward near the ground level.

  19. Controlling Vapor Pressure In Hanging-Drop Crystallization

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Smith, Robbie

    1988-01-01

    Rate of evaporation adjusted to produce larger crystals. Device helps to control vapor pressure of water and other solvents in vicinity of hanging drop of solution containing dissolved enzyme protein. Well of porous frit (sintered glass) holds solution in proximity to drop of solution containing protein or enzyme. Vapor from solution in frit controls evaporation of solvent from drop to control precipitation of protein or enzyme. With device, rate of nucleation limited to decrease number and increase size (and perhaps quality) of crystals - large crystals of higher quality needed for x-ray diffraction studies of macromolecules.

  20. A new photocatalytic reactor for trace contaminant control: a water polishing system.

    PubMed

    Gonzalez-Martin, A; Kim, J; Van Hyfte, J; Rutherford, L A; Andrews, C

    2001-01-01

    In spacecraft water recovery systems there is a need to develop a postprocessor water polishing system to remove organic impurities to levels below 250 micrograms/L (ppb) with a minimum use of expendables. This article addresses the development of a photocatalytic process as a postprocessor water polishing system that is microgravity compatible, operates at room temperature, and requires only a minimal use of both oxygen gas (or air) and electrical power for low energy UV-A (315-400 nm) lamps. In the photocatalytic process, organic contaminants are degraded to benign end products on semiconductor surfaces, usually TiO2. Some challenging issues related to the use of TiO2 for the degradation of organic contaminants have been addressed. These include: i) efficient and stable catalytic material; ii) immobilization of the catalyst to produce a high surface area material that can be used in packed-bed reactors, iii) effective light penetration, iv) effective, microgravity-compatible, oxidant delivery; v) reduced pressure drop, and vi) minimum retention time. The research and development performed on this photocatalytic process is presented in detail. Grant numbers: NAS9-97182.

  1. Gasdynamic Inlet Isolation in Rotating Detonation Engine

    DTIC Science & Technology

    2010-12-01

    2D Total Variation Diminishing (TVD): Continuous Riemann Solver Minimum Dissipation: LHS & RHS Activate pressure switch : Supersonic Activate...Total Variation Diminishing (TVD) limiter: Continuous Riemann Solver Minimum Dissipation: LHS & RHS Activate pressure switch : Supersonic Activate...Continuous 94 Riemann Solver Minimum Dissipation: LHS & RHS Activate pressure switch : Supersonic Activate pressure gradient switch: Normal

  2. Pressure Drop Across Woven Screens Under Uniform and Nonuniform Flow Conditions. [flow characteristics of water through Dutch twill and square weave fabrics

    NASA Technical Reports Server (NTRS)

    Ludewig, M.; Omori, S.; Rao, G. L.

    1974-01-01

    Tests were conducted to determine the experimental pressure drop and velocity data for water flowing through woven screens. The types of materials used are dutch twill and square weave fabrics. Pressure drop measures were made at four locations in a rectangular channel. The data are presented as change in pressure compared with the average entry velocity and the numerical relationship is determined by dividing the volumetric flow rate by the screen area open to flow. The equations of continuity and momentum are presented. A computer program listing an extension of a theoretical model and data from that computer program are included.

  3. 40 CFR 63.9920 - What are my continuous monitoring requirements?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b), you must at all times monitor the hourly average pressure drop and liquid flow rate using a CPMS...

  4. 40 CFR 63.9920 - What are my continuous monitoring requirements?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b), you must at all times monitor the hourly average pressure drop and liquid flow rate using a CPMS...

  5. 40 CFR 63.9920 - What are my continuous monitoring requirements?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... scrubber subject to the operating limits for pressure drop and scrubber water flow rates in § 63.9890(b), you must at all times monitor the hourly average pressure drop and liquid flow rate using a CPMS...

  6. Comparison of High Aspect Ratio Cooling Channel Designs for a Rocket Combustion Chamber with Development of an Optimized Design

    NASA Technical Reports Server (NTRS)

    Wadel, Mary F.

    1998-01-01

    An analytical investigation on the effect of high aspect ratio (height/width) cooling channels, considering different coolant channel designs, on hot-gas-side wall temperature and coolant pressure drop for a liquid hydrogen cooled rocket combustion chamber, was performed. Coolant channel design elements considered were: length of combustion chamber in which high aspect ratio cooling was applied, number of coolant channels, and coolant channel shape. Seven coolant channel designs were investigated using a coupling of the Rocket Thermal Evaluation code and the Two-Dimensional Kinetics code. Initially, each coolant channel design was developed, without consideration for fabrication, to reduce the hot-gas-side wall temperature from a given conventional cooling channel baseline. These designs produced hot-gas-side wall temperature reductions up to 22 percent, with coolant pressure drop increases as low as 7.5 percent from the baseline. Fabrication constraints for milled channels were applied to the seven designs. These produced hot-gas-side wall temperature reductions of up to 20 percent, with coolant pressure drop increases as low as 2 percent. Using high aspect ratio cooling channels for the entire length of the combustion chamber had no additional benefit on hot-gas-side wall temperature over using high aspect ratio cooling channels only in the throat region, but increased coolant pressure drop 33 percent. Independent of coolant channel shape, high aspect ratio cooling was able to reduce the hot-gas-side wall temperature by at least 8 percent, with as low as a 2 percent increase in coolant pressure drop. ne design with the highest overall benefit to hot-gas-side wall temperature and minimal coolant pressure drop increase was the design which used bifurcated cooling channels and high aspect ratio cooling in the throat region. An optimized bifurcated high aspect ratio cooling channel design was developed which reduced the hot-gas-side wall temperature by 18 percent and reduced the coolant pressure drop by 4 percent. Reductions of coolant mass flow rate of up to 50 percent were possible before the hot-gas-side wall temperature reached that of the baseline. These mass flow rate reductions produced coolant pressure drops of up to 57 percent.

  7. A steady state pressure drop model for screen channel liquid acquisition devices

    NASA Astrophysics Data System (ADS)

    Hartwig, J. W.; Darr, S. R.; McQuillen, J. B.; Rame, E.; Chato, D. J.

    2014-11-01

    This paper presents the derivation of a simplified one dimensional (1D) steady state pressure drop model for flow through a porous liquid acquisition device (LAD) inside a cryogenic propellant tank. Experimental data is also presented from cryogenic LAD tests in liquid hydrogen (LH2) and liquid oxygen (LOX) to compare against the simplified model and to validate the model at cryogenic temperatures. The purpose of the experiments was to identify the various pressure drop contributions in the analytical model which govern LAD channel behavior during dynamic, steady state outflow. LH2 pipe flow of LAD screen samples measured the second order flow-through-screen (FTS) pressure drop, horizontal LOX LAD outflow tests determined the relative magnitude of the third order frictional and dynamic losses within the channel, while LH2 inverted vertical outflow tests determined the magnitude of the first order hydrostatic pressure loss and validity of the full 1D model. When compared to room temperature predictions, the FTS pressure drop is shown to be temperature dependent, with a significant increase in flow resistance at LH2 temperatures. Model predictions of frictional and dynamic losses down the channel compare qualitatively with LOX LADs data. Meanwhile, the 1D model predicted breakdown points track the trends in the LH2 inverted outflow experimental results, with discrepancies being due to a non-uniform injection velocity across the LAD screen not accounted for in the model.

  8. Effect of Water Cut on Pressure Drop of Oil (D130) -Water Flow in 4″Horizontal Pipe

    NASA Astrophysics Data System (ADS)

    Basha, Mehaboob; Shaahid, S. M.; Al-Hems, Luai M.

    2018-03-01

    The oil-water flow in pipes is a challenging subject that is rich in physics and practical applications. It is often encountered in many oil and chemical industries. The pressure gradient of two phase flow is still subject of immense research. The present study reports pressure measurements of oil (D130)-water flow in a horizontal 4″ diameter stainless steel pipe at different flow conditions. Experiments were carried out for different water cuts (WC); 0-100%. Inlet oil-water flow rates were varied from 4000 to 8000 barrels-per-day in steps of 2000. It has been found that the frictional pressure drop decreases for WC = 0 - 40 %. With further increase in WC, friction pressure drop increases, this could be due to phase inversion.

  9. Steady RANS methodology for calculating pressure drop in an in-line molten salt compact crossflow heat exchanger

    DOE PAGES

    Carasik, Lane B.; Shaver, Dillon R.; Haefner, Jonah B.; ...

    2017-08-21

    We report the development of molten salt cooled reactors (MSR) and fluoride-salt cooled high temperature reactors (FHR) requires the use of advanced design tools for the primary heat exchanger design. Due to geometric and flow characteristics, compact (pitch to diameter ratios equal to or less than 1.25) heat exchangers with a crossflow flow arrangement can become desirable for these reactors. Unfortunately, the available experimental data is limited for compact tube bundles or banks in crossflow. Computational Fluid Dynamics can be used to alleviate the lack of experimental data in these tube banks. Previous computational efforts have been primarily focused onmore » large S/D ratios (larger than 1.4) using unsteady Reynolds averaged Navier-Stokes and Large Eddy Simulation frameworks. These approaches are useful, but have large computational requirements that make comprehensive design studies impractical. A CFD study was conducted with steady RANS in an effort to provide a starting point for future design work. The study was performed for an in-line tube bank geometry with FLiBe (LiF-BeF2), a frequently selected molten salt, as the working fluid. Based on the estimated pressure drops, the pressure and velocity distributions in the domain, an appropriate meshing strategy was determined and presented. Periodic boundaries in the spanwise direction transverse flow were determined to be an appropriate boundary condition for reduced computational domains. The domain size was investigated and a minimum of 2-flow channels for a domain is recommended to ensure the behavior is accounted for. Finally, the standard low Re κ-ε (Lien) turbulence model was determined to be the most appropriate for steady RANS of this case at the time of writing.« less

  10. Steady RANS methodology for calculating pressure drop in an in-line molten salt compact crossflow heat exchanger

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Carasik, Lane B.; Shaver, Dillon R.; Haefner, Jonah B.

    We report the development of molten salt cooled reactors (MSR) and fluoride-salt cooled high temperature reactors (FHR) requires the use of advanced design tools for the primary heat exchanger design. Due to geometric and flow characteristics, compact (pitch to diameter ratios equal to or less than 1.25) heat exchangers with a crossflow flow arrangement can become desirable for these reactors. Unfortunately, the available experimental data is limited for compact tube bundles or banks in crossflow. Computational Fluid Dynamics can be used to alleviate the lack of experimental data in these tube banks. Previous computational efforts have been primarily focused onmore » large S/D ratios (larger than 1.4) using unsteady Reynolds averaged Navier-Stokes and Large Eddy Simulation frameworks. These approaches are useful, but have large computational requirements that make comprehensive design studies impractical. A CFD study was conducted with steady RANS in an effort to provide a starting point for future design work. The study was performed for an in-line tube bank geometry with FLiBe (LiF-BeF2), a frequently selected molten salt, as the working fluid. Based on the estimated pressure drops, the pressure and velocity distributions in the domain, an appropriate meshing strategy was determined and presented. Periodic boundaries in the spanwise direction transverse flow were determined to be an appropriate boundary condition for reduced computational domains. The domain size was investigated and a minimum of 2-flow channels for a domain is recommended to ensure the behavior is accounted for. Finally, the standard low Re κ-ε (Lien) turbulence model was determined to be the most appropriate for steady RANS of this case at the time of writing.« less

  11. Intraocular pressure and cerebral oxygenation during prolonged headward acceleration.

    PubMed

    Eiken, Ola; Keramidas, Michail E; Taylor, Nigel A S; Grönkvist, Mikael

    2017-01-01

    Supra-tolerance head-to-foot directed gravitoinertial load (+Gz) typically induces a sequence of symptoms/signs, including loss of: peripheral vision-central vision-consciousness. The risk of unconsciousness is greater when anti-G-garment failure occurs after prolonged rather than brief exposures, presumably because, in the former condition, mental signs are not consistently preceded by impaired vision. The aims were to investigate if prolonged exposure to moderately elevated +Gz reduces intraocular pressure (IOP; i.e., improves provisions for retinal perfusion), or the cerebral anoxia reserve. Subjects were exposed to 4-min +Gz plateaux either at 2 and 3 G (n = 10), or at 4 and 5 G (n = 12). Measurements included eye-level mean arterial pressure (MAP), oxygenation of the cerebral frontal cortex, and at 2 and 3 G, IOP. IOP was similar at 1 (14.1 ± 1.6 mmHg), 2 (14.0 ± 1.6 mmHg), and 3 G (14.0 ± 1.6 mmHg). During the G exposures, MAP exhibited an initial prompt drop followed by a partial recovery, end-exposure values being reduced by ≤30 mmHg. Cerebral oxygenation showed a similar initial drop, but without recovery, and was followed by either a plateau or a further slight decrement to a minimum of about -14 μM. Gz loading did not affect IOP. That cerebral oxygenation remained suppressed throughout these G exposures, despite a concomitant partial recovery of MAP, suggests that the increased risk of unconsciousness upon G-garment failure after prolonged +Gz exposure is due to reduced cerebral anoxia reserve.

  12. Study on Transfer Rules of Coal Reservoir Pressure Drop Based on Coalbed Methane Well Drainage Experiments

    NASA Astrophysics Data System (ADS)

    Yuhang, X.

    2017-12-01

    A pumping test was carried out to explore the transfer rules of pressure drop in coal reservoir during the drainage. The experiment was divided into three stages. In the first stage, the pump displacement of 3m3/h was used to reduce the bottom hole flowing pressure and stopped until the continuous gas phase was produced; Undertaking the first stage, in the second stage, when the gas phase was continuously produced, the pump was stopped immediately. As the bottom hole flowing pressure going up without gas phase, pumping started again for a week. In the third stage ,the well pumping was carried out at the bottom hole pressure drop rate of 30Kpa/d after two months' recovery. Combined with the data of regional geology and fractured well, taking the characteristics of macroscopic coal rocks, development of pore and fracture in coal and isothermal adsorption test as the background, the features of reservoir output in each stage of the experiment were analyzed and compared, and then the transfer rules of pressure drop contained in the differences of the output was studied further. In the first and third stage of the experiment, the output of liquid phase was much larger than the space volume of coal reservoir pore and fracture in the range of 100m2. In the second stage, the output of the continuous gas phase appeared around 0.7Mpa when the continuous gas phase appears below the critical desorption pressure of 0.25Mpa during the whole experiment. The results indicate that, the transfer of pressure drop in the coal reservoir of this well is mainly horizontal, and the liquid phase produced in the reservoir mainly comes from the recharge of the reservoir at the far end of the relative high pressure area; the adsorption space of coalbed methane in the coal matrix as well as the main migration channel of fluid in the reservoir doesn't belong to the same pressure system and there exists the communication barrier between them. In addition, the increasing of the effective stress has little influence on the communication between these two systems. The definition of transfer rules in coal reservoir pressure drop, also the understanding of the correlation between the rules and characteristics of the reservoir output has great guiding significance to the establishment of pressure drop system in coalbed methane well as well as the analysis of production problems.

  13. Numerical simulation on the powder propellant pickup characteristics of feeding system at high pressure

    NASA Astrophysics Data System (ADS)

    Sun, Haijun; Hu, Chunbo; Zhu, Xiaofei

    2017-10-01

    A numerical study of powder propellant pickup progress at high pressure was presented in this paper by using two-fluid model with kinetic theory of granular flow in the computational fluid dynamics software package ANSYS/Fluent. Simulations were conducted to evaluate the effects of initial pressure, initial powder packing rate and mean particle diameter on the flow characteristics in terms of velocity vector distribution, granular temperature, pressure drop, particle velocity and volume. The numerical results of pressure drop were also compared with experiments to verify the TFM model. The simulated results show that the pressure drop value increases as the initial pressure increases, and the granular temperature under the conditions of different initial pressures and packing rates is almost the same in the area of throttling orifice plate. While there is an appropriate value for particle size and packing rate to form a ;core-annulus; structure in powder box, and the time-averaged velocity vector distribution of solid phase is inordinate.

  14. Hydrodynamic shrinkage of liquid CO2 Taylor drops in a straight microchannel

    NASA Astrophysics Data System (ADS)

    Qin, Ning; Wen, John Z.; Ren, Carolyn L.

    2018-03-01

    Hydrodynamic shrinkage of liquid CO2 drops in water under a Taylor flow regime is studied using a straight microchannel (length/width ~100). A general form of a mathematical model of the solvent-side mass transfer coefficient (k s) is developed first. Based on formulations of the surface area (A) and the volume (V) of a general Taylor drop in a rectangular microchannel, a specific form of k s is derived. Drop length and speed are experimentally measured at three specified positions of the straight channel, namely, immediately after drop generation (position 1), the midpoint of the channel (position 2) and the end of the channel (position 3). The reductions of drop length (L x , x  =  1, 2, 3) from position 1 to 2 and down to 3 are used to quantify the drop shrinkage. Using the specific model, k s is calculated mainly based on L x and drop flowing time (t). Results show that smaller CO2 drops produced by lower flow rate ratios ({{Q}LC{{O2}}}/{{Q}{{H2}O}} ) are generally characterized by higher (nearly three times) k s and Sherwood numbers than those produced by higher {{Q}LC{{O2}}}/{{Q}{{H2}O}} , which is essentially attributed to the larger effective portion of the smaller drop contributing in the mass transfer under same levels of the flowing time and the surface-to-volume ratio (~104 m-1) of all drops. Based on calculated pressure drops of the segmented flow in microchannel, the Peng-Robinson equation of state and initial pressures of drops at the T-junction in experiments, overall pressure drop (ΔP t) in the straight channel as well as the resulted drop volume change are quantified. ΔP t from position 1-3 is by average 3.175 kPa with a ~1.6% standard error, which only leads to relative drop volume changes of 0.3‰ to 0.52‰.

  15. Study on atomization features of a plain injector in high speed transverse air stream

    NASA Astrophysics Data System (ADS)

    Wan, Jian; Gu, Shanjian; Yang, Maolin; Xiao, Weihui

    1990-04-01

    The atomization features of a plain injector in high-speed transverse air stream were investigated by Malvern. In this investigation, air velocity ranged from 50-150m/s, pressure drop of fuel injector, (1.1 - 4.2) x 10 to the 6th Pa, diameter of orifice, 0.5 - 0.9 mm, axial distance between the injector and the survey plane, 50 - 250 mm. Aviation kerosene was used in all experiments. It was found that the atomization features in high pressure drop of fuel injector were greatly differed from the low pressure drop of fuel injector.

  16. The respective effect of under-rib convection and pressure drop of flow fields on the performance of PEM fuel cells

    PubMed Central

    Wang, Chao; Zhang, Qinglei; Shen, Shuiyun; Yan, Xiaohui; Zhu, Fengjuan; Cheng, Xiaojing; Zhang, Junliang

    2017-01-01

    The flow field configuration plays an important role on the performance of proton exchange membrane fuel cells (PEMFCs). For instance, channel/rib width and total channel cross-sectional area determine the under-rib convection and pressure drop respectively, both of which directly influence the water removal, in turn affecting the oxygen supply and cathodic oxygen reduction reaction. In this study, effects of under-rib convection and pressure drop on cell performance are investigated experimentally and numerically by adjusting the channel/rib width and channel cross-sectional area of flow fields. The results show that the performance differences with various flow field configurations mainly derive from the oxygen transport resistance which is determined by the water accumulation degree, and the cell performance would benefit from the narrower channels and smaller cross sections. It reveals that at low current densities when water starts to accumulate in GDL at under-rib regions, the under-rib convection plays a more important role in water removal than pressure drop does; in contrast, at high current densities when water starts to accumulate in channels, the pressure drop dominates the water removal to facilitate the oxygen transport to the catalyst layer. PMID:28251983

  17. Nonspherical particles in a pseudo-2D fluidized bed: Experimental study.

    PubMed

    Mahajan, Vinay V; Padding, Johan T; Nijssen, Tim M J; Buist, Kay A; Kuipers, J A M

    2018-05-01

    Fluidization is widely used in industries and has been extensively studied, both experimentally and theoretically, in the past. However, most of these studies focus on spherical particles while in practice granules are rarely spherical. Particle shape can have a significant effect on fluidization characteristics. It is therefore important to study the effect of particle shape on fluidization behavior in detail. In this study, experiments in pseudo-2D fluidized beds are used to characterize the fluidization of spherocylindrical (rod-like) Geldart D particles of aspect ratio 4. Pressure drop and optical measurement methods (Digital Image Analysis, Particle Image Velocimetry, Particle Tracking Velocimetry) are employed to measure bed height, particle orientation, particle circulation, stacking, and coordination number. The commonly used correlations to determine the pressure drop across a bed of nonspherical particles are compared to experiments. Experimental observations and measurements have shown that rod-like particles are prone to interlocking and channeling behavior. Well above the minimum fluidization velocity, vigorous bubbling fluidization is observed, with groups of interlocked particles moving upwards, breaking up, being thrown high in the freeboard region and slowly raining down as dispersed phase. At high flowrates, a circulation pattern develops with particles moving up through the center and down at the walls. Particles tend to orient themselves along the flow direction. © 2018 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers , 64: 1573-1590, 2018.

  18. Nonspherical particles in a pseudo‐2D fluidized bed: Experimental study

    PubMed Central

    Mahajan, Vinay V.; Nijssen, Tim M. J.; Buist, Kay A.; Kuipers, J. A. M.

    2018-01-01

    Fluidization is widely used in industries and has been extensively studied, both experimentally and theoretically, in the past. However, most of these studies focus on spherical particles while in practice granules are rarely spherical. Particle shape can have a significant effect on fluidization characteristics. It is therefore important to study the effect of particle shape on fluidization behavior in detail. In this study, experiments in pseudo‐2D fluidized beds are used to characterize the fluidization of spherocylindrical (rod‐like) Geldart D particles of aspect ratio 4. Pressure drop and optical measurement methods (Digital Image Analysis, Particle Image Velocimetry, Particle Tracking Velocimetry) are employed to measure bed height, particle orientation, particle circulation, stacking, and coordination number. The commonly used correlations to determine the pressure drop across a bed of nonspherical particles are compared to experiments. Experimental observations and measurements have shown that rod‐like particles are prone to interlocking and channeling behavior. Well above the minimum fluidization velocity, vigorous bubbling fluidization is observed, with groups of interlocked particles moving upwards, breaking up, being thrown high in the freeboard region and slowly raining down as dispersed phase. At high flowrates, a circulation pattern develops with particles moving up through the center and down at the walls. Particles tend to orient themselves along the flow direction. © 2018 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 64: 1573–1590, 2018 PMID:29706659

  19. High-Pressure Transport Properties Of Fluids: Theory And Data From Levitated Drops At Combustion-Relevant Temperatures

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Harstad, Kenneth; Ohsaka, Kenichi

    2003-01-01

    Although the high pressure multicomponent fluid conservation equations have already been derived and approximately validated for binary mixtures by this PI, the validation of the multicomponent theory is hampered by the lack of existing mixing rules for property calculations. Classical gas dynamics theory can provide property mixing-rules at low pressures exclusively. While thermal conductivity and viscosity high-pressure mixing rules have been documented in the literature, there is no such equivalent for the diffusion coefficients and the thermal diffusion factors. The primary goal of this investigation is to extend the low pressure mixing rule theory to high pressures and validate the new theory with experimental data from levitated single drops. The two properties that will be addressed are the diffusion coefficients and the thermal diffusion factors. To validate/determine the property calculations, ground-based experiments from levitated drops are being conducted.

  20. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or lower are considered... with a capacity of 0.45 cubic meters (15.9 cubic feet) or less must be subject to an additional drop... material having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...

  1. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or lower are considered... with a capacity of 0.45 cubic meters (15.9 cubic feet) or less must be subject to an additional drop... material having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...

  2. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... solutions with a minimum specific gravity of 0.95 for testing at −18 °C (0 °F) or lower are considered... with a capacity of 0.45 cubic meters (15.9 cubic feet) or less must be subject to an additional drop... material having essentially the same physical characteristics. (3) The specific gravity and viscosity of a...

  3. Study of two-phase flow in helical and spiral coils

    NASA Technical Reports Server (NTRS)

    Keshock, Edward G.; Yan, AN; Omrani, Adel

    1990-01-01

    The principal purposes of the present study were to: (1) observe and develop a fundamental understanding of the flow regimes and their transitions occurring in helical and spiral coils; and (2) obtain pressure drop measurements of such flows, and, if possible, develop a method for predicting pressure drop in these flow geometries. Elaborating upon the above, the general intent is to develop criteria (preferably generalized) for establishing the nature of the flow dynamics (e.g. flow patterns) and the magnitude of the pressure drop in such configurations over a range of flow rates and fluid properties. Additionally, the visualization and identification of flow patterns were a fundamental objective of the study. From a practical standpoint, the conditions under which an annular flow pattern exists is of particular practical importance. In the possible practical applications which would implement these geometries, the working fluids are likely to be refrigerant fluids. In the present study the working fluids were an air-water mixture, and refrigerant 113 (R-113). In order to obtain records of flow patterns and their transitions, video photography was employed extensively. Pressure drop measurements were made using pressure differential transducers connected across pressure taps in lines immediately preceding and following the various test sections.

  4. Effects of vascular structures on the pressure drop in stenotic coronary arteries

    NASA Astrophysics Data System (ADS)

    Kim, Jaerim; Choi, Haecheon; Kweon, Jihoon; Kim, Young-Hak; Yang, Dong Hyun; Kim, Namkug

    2016-11-01

    A stenosis, which is a narrowing of a blood vessel, of the coronary arteries restricts the flow to the heart and it may lead to sudden cardiac death. Therefore, the accurate determination of the severity of a stenosis is a critical issue. Due to the convenience of visual assessments, geometric parameters such as the diameter stenosis and area stenosis have been used, but the decision based on them sometimes under- or overestimates the functional severity of a stenosis, i.e., pressure drop. In this study, patient-specific models that have similar area stenosis but different pressure drops are considered, and their geometries are reconstructed from the coronary computed tomography angiography (CCTA). Both steady and pulsatile inflows are considered for the simulations. Comparison between two models that have a bifurcation right after a stenosis shows that the parent to daughter vessel angle results in different secondary flow patterns and wall shear stress distributions which affect the pressure downstream. Thus, the structural features of the lower and upper parts of a stenosis significantly affect the pressure drop. Supported by 20152020105600.

  5. Gas-Liquid Packed Bed Reactors in Microgravity

    NASA Technical Reports Server (NTRS)

    Balakotaiah, Vemuri; Motil, Brian J.; McCready, Mark J.; Kamotani, Yasuhiro

    2004-01-01

    Flow regime and pressure drop data was obtained and analyzed. Pulse flow exists at lower liquid flow rates in 0-g compared to 1-g. 1-g flow regime maps do not apply in microgravity. Pressure drop is higher in microgravity (enhanced interfacial effects).

  6. Plasma rich in growth factors eye drops to treat secondary ocular surface disorders in patients with glaucoma

    PubMed Central

    Sánchez-Avila, Ronald M; Merayo-Lloves, Jesus; Fernández, Maria Laura; Rodríguez-Gutiérrez, Luis Alberto; Rodríguez-Calvo, Pedro Pablo; Fernández-Vega Cueto, Andres; Muruzabal, Francisco; Orive, Gorka; Anitua, Eduardo

    2018-01-01

    Purpose To evaluate the efficacy and safety of plasma rich in growth factors (PRGF) eye drops in patients with glaucoma with secondary ocular surface disorders (OSDs) due to surgeries and topical hypotensive drugs use. Materials and methods A retrospective case-series study design was used including six patients (eight eyes) diagnosed with glaucoma who received surgical (nonpenetrating deep sclerectomy and/or trabeculectomy) and medical treatments (hypotensive eye drops) to control intraocular pressure (IOP) and who developed secondary OSDs, unresponsive to conventional treatments. Patients were treated with PRGF eye drops (four times a day). Outcome measures were ocular surface disease index (OSDI), best-corrected visual acuity (BCVA, in logarithm of the minimum angle of resolution), visual analog scale (VAS), frequency and severity of symptoms, and IOP. The safety of the treatment was also evaluated. Results Six patients (seven eyes with open-angle glaucoma and one eye with uveitic glaucoma) treated with PRGF eye drops were evaluated. Mean age was 71 years (SD=7.2, range 58–79 years). Five were female and one was male. The mean treatment time was 21.8 weeks (SD=9.0, range 12–36 weeks). The mean time to reach closure of the corneal ulcer was 14.5 (SD=5.5) weeks. A statistical significant reduction in OSDI scale (50.6%), VAS frequency (53.1%), VAS severity (42.0%), and a 41.8% improvement in BCVA were observed (p<0.05). IOP also decreased by 16.6% (p=0.010). Only one of the six patients reported itching in both eyes as an adverse event (AE); however, the patient continued with the PRGF eye drops until the end of therapy; the remaining patients did not report any AEs during the follow-up period. Conclusions In patients with glaucoma and secondary OSDs refractive to conventional treatments, the treatment with PRGF eye drops could be considered a possible therapeutic option, because it demonstrates an improvement in the signs and symptoms of the ocular surface, as well as a better control of the IOP. This is an initial research work that can open doors for future research to confirm these findings. PMID:29760570

  7. Plasma rich in growth factors eye drops to treat secondary ocular surface disorders in patients with glaucoma.

    PubMed

    Sánchez-Avila, Ronald M; Merayo-Lloves, Jesus; Fernández, Maria Laura; Rodríguez-Gutiérrez, Luis Alberto; Rodríguez-Calvo, Pedro Pablo; Fernández-Vega Cueto, Andres; Muruzabal, Francisco; Orive, Gorka; Anitua, Eduardo

    2018-01-01

    To evaluate the efficacy and safety of plasma rich in growth factors (PRGF) eye drops in patients with glaucoma with secondary ocular surface disorders (OSDs) due to surgeries and topical hypotensive drugs use. A retrospective case-series study design was used including six patients (eight eyes) diagnosed with glaucoma who received surgical (nonpenetrating deep sclerectomy and/or trabeculectomy) and medical treatments (hypotensive eye drops) to control intraocular pressure (IOP) and who developed secondary OSDs, unresponsive to conventional treatments. Patients were treated with PRGF eye drops (four times a day). Outcome measures were ocular surface disease index (OSDI), best-corrected visual acuity (BCVA, in logarithm of the minimum angle of resolution), visual analog scale (VAS), frequency and severity of symptoms, and IOP. The safety of the treatment was also evaluated. Six patients (seven eyes with open-angle glaucoma and one eye with uveitic glaucoma) treated with PRGF eye drops were evaluated. Mean age was 71 years (SD=7.2, range 58-79 years). Five were female and one was male. The mean treatment time was 21.8 weeks (SD=9.0, range 12-36 weeks). The mean time to reach closure of the corneal ulcer was 14.5 (SD=5.5) weeks. A statistical significant reduction in OSDI scale (50.6%), VAS frequency (53.1%), VAS severity (42.0%), and a 41.8% improvement in BCVA were observed ( p <0.05). IOP also decreased by 16.6% ( p =0.010). Only one of the six patients reported itching in both eyes as an adverse event (AE); however, the patient continued with the PRGF eye drops until the end of therapy; the remaining patients did not report any AEs during the follow-up period. In patients with glaucoma and secondary OSDs refractive to conventional treatments, the treatment with PRGF eye drops could be considered a possible therapeutic option, because it demonstrates an improvement in the signs and symptoms of the ocular surface, as well as a better control of the IOP. This is an initial research work that can open doors for future research to confirm these findings.

  8. D0 Silicon Upgrade: ASME Code and Pressure Calculations for Liquid Nitrogen Subcooler

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kuwazaki, Andrew; Leicht, Todd; /Fermilab

    1995-10-04

    Included in this engineering note are three separate calculation divisions. The first calculations are the determination of the required thickness of the LN{sub 2} subcooler flat head according to ASME code. This section includes Appendix A-C. The minimum plate thickness determined was 0.563 in. The actual thickness chosen in fabrication was a 3/4-inch plate milled to 0.594-inch at the bolt circle. Along with the plate thickness, this section calculates the required reinforcement area at the top plate penetrations. It was found that a 1/4-inch fillet weld at each penetration was adequate. The next set of calculations were done to provemore » that the subcooler internal pressure will always be less than 15 psig and therefore will not be classified as a pressure vessel. The subcooler is always open to a vent pipe. Appendix D calculations show that the vent pipe has a capacity of 1042 lbs/hr if 15 psig is present at the subcooler. It goes on to show that the inlet piping would at that flow rate, see a pressure drop of 104 psig. The maximum supply pressure of the LN{sub 2} storage dewar is 50 psig. Appendix E addresses required flow rates for steady state, loss of vacuum, or fire conditions. Page E9 shows a summary which states the maximum pressure would be 1.50 psig at fire conditions and internal pressure.« less

  9. Complete temperature profiles in ultra-high-pressure liquid chromatography columns.

    PubMed

    Gritti, Fabrice; Guiochon, Georges

    2008-07-01

    The temperature profiles were calculated along and across seven packed columns (lengths 30, 50, 100, and 150 mm, i.d., 1 and 2.1 mm, all packed with Acquity UPLC, BEH-C 18 particles, average d(p) approximately 1.7 microm) and their stainless steel tubes (o.d. 4.53 and 6.35 mm). These columns were kept horizontal and sheltered from forced air convection (i.e., under still air conditions), at room temperature. They were all percolated with pure acetonitrile, either under the maximum pressure drop (1034 bar) or at the maximum flow rate (2 mL/min) permitted by the chromatograph. The heat balance equation of chromatographic columns was discretized and solved numerically with minimum approximation. Both the compressibility and the thermal expansion of the eluent were taken into account. The boundary conditions were determined from the experimental measurements of the column inlet pressure and of the temperature profile along the column wall, which were made with a precision better than +/-0.1 K. These calculation results provide the 3-D temperature profiles along and across the columns. The axial and radial temperature gradients are discussed in relationship with the experimental conditions used. The temperature map obtained permits a prediction of the chromatographic data obtained under a very high pressure gradient.

  10. Evaluation of Open Cell Foam Heat Transfer Enhancement for Liquid Rocket Engine

    NASA Technical Reports Server (NTRS)

    Chung, J. N.; Tully, Landon; Kim, Jung Hwan; Jones, Gregg W.; Watkins, William

    2006-01-01

    As NASA pursues the exploration mission, advanced propulsion for the next generation of spacecraft will be needed. These new propulsion systems will require higher performance and increased durability, despite current limitations on materials. A break-through technology is needed in the thrust chamber. In this paper the idea of using a porous metallic foam is examined for its potential cooling enhancement capabilities. The goal is to increase the chamber wall cooling without creating an additional pressure drop penalty. A feasibility study based on experiments at laboratory-scale conditions was performed and analysis at rocket conditions is underway. In the experiment, heat transfer and pressure drop data were collected using air as the coolant in a copper or nickel foam filled annular channel. The foam-channel performance was evaluated based on comparison with conventional microchannel cooling passages under equal pressure drop conditions. The heat transfer enhancement of the foam channel over the microchannel ranges from 130% to 172%. The enhancement is relatively independent of the pressure drop and increases with decreasing pore size. A direct numerical simulation model of the foam heat exchange has been built. The model is based on the actual metal foam microstructure of thin ligaments (0.2- 0.3 mm in diameter) that form a network of interconnected open-cells. The cell dimension is around 2 mm. The numerical model was built using the FLUENT CFD code. Comparison of the pressure drop results predicted by the current model with those experimental data of Leong and Jin [8] shows favorable comparisons. Pressure drop predictions have been made using hydrogen as a coolant at typical rocket conditions. Conjugate heat transfer analysis using the foam filled channel is planned for the future.

  11. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barleon, L.; Buehler, L.; Molokov, S.

    Magnetohydrodynamic (MHD) flow through a 90{degrees} bend, in which the flow is turned from the direction perpendicular to magnetic field lines into a direction aligned with the field, is characterized by strong three-dimensional effects leading to additional pressure drop and large deformations in the velocity distribution. Since such bends are basic elements of a fusion reactor blanket, the question whether the additional pressure drop exceeds unacceptable limits or whether the change in flow distribution may lead to unfavorable heat transfer conditions as to be answered. To investigate MHD flows in a right angle bend, several experiments have been performed inmore » a wide range of the relevant parameters. In the lower range of the interaction parameter N (N {much_lt} 10{sup 4}) the total pressure drop over the whole bend shows a pronounced N-dependence but only a weak dependence on the Hartmann number M. Both effects can be combined to a pressure drop correlation. At higher values of N and M the experimental results for pressure drop and potential distribution agree rather well with theoretical ones obtained on the basis of an asymptotic approach for high N and M. It can be shown theoretically and confirmed by the experiment that, even at high N and M the additional pressure drop in a right angle bend is not excessively high. For the investigated bend with conducting channel walls the predicted flow distribution does not show any stagnant zone at the high heat flux walls in the perfectly aligned part of the duct. This result, however, could not be checked experimentally because there is still no reliable velocity measurement technique available for field-aligned flows.« less

  12. Pressure drop reduction and heat transfer deterioration of slush nitrogen in triangular and circular pipe flows

    NASA Astrophysics Data System (ADS)

    Ohira, Katsuhide; Kurose, Kizuku; Okuyama, Jun; Saito, Yutaro; Takahashi, Koichi

    2017-01-01

    Slush fluids such as slush hydrogen and slush nitrogen are characterized by superior properties as functional thermal fluids due to their density and heat of fusion. In addition to allowing efficient hydrogen transport and storage, slush hydrogen can serve as a refrigerant for high-temperature superconducting (HTS) equipment using MgB2, with the potential for synergistic effects. In this study, pressure drop reduction and heat transfer deterioration experiments were performed on slush nitrogen flowing in a horizontal triangular pipe with sides of 20 mm under the conditions of three different cross-sectional orientations. Experimental conditions consisted of flow velocity (0.3-4.2 m/s), solid fraction (0-25 wt.%), and heat flux (0, 10, and 20 kW/m2). Pressure drop reduction became apparent at flow velocities exceeding about 1.3-1.8 m/s, representing a maximum amount of reduction of 16-19% in comparison with liquid nitrogen, regardless of heating. Heat transfer deterioration was seen at flow velocities of over 1.2-1.8 m/s, for a maximum amount of deterioration of 13-16%. The authors of the current study compared the results for pressure drop reduction and heat transfer deterioration in triangular pipe with those obtained previously for circular and square pipes, clarifying differences in flow and heat transfer properties. Also, a correlation equation was obtained between the slush Reynolds number and the pipe friction factor, which is important in the estimation of pressure drop in unheated triangular pipe. Furthermore, a second correlation equation was derived between the modified slush Reynolds number and the pipe friction factor, enabling the integrated prediction of pressure drop in both unheated triangular and circular pipes.

  13. Numerical study of canister filters with alternatives filter cap configurations

    NASA Astrophysics Data System (ADS)

    Mohammed, A. N.; Daud, A. R.; Abdullah, K.; Seri, S. M.; Razali, M. A.; Hushim, M. F.; Khalid, A.

    2017-09-01

    Air filtration system and filter play an important role in getting a good quality air into turbo machinery such as gas turbine. The filtration system and filter has improved the quality of air and protect the gas turbine part from contaminants which could bring damage. During separation of contaminants from the air, pressure drop cannot be avoided but it can be minimized thus helps to reduce the intake losses of the engine [1]. This study is focused on the configuration of the filter in order to obtain the minimal pressure drop along the filter. The configuration used is the basic filter geometry provided by Salutary Avenue Manufacturing Sdn Bhd. and two modified canister filter cap which is designed based on the basic filter model. The geometries of the filter are generated by using SOLIDWORKS software and Computational Fluid Dynamics (CFD) software is used to analyse and simulates the flow through the filter. In this study, the parameters of the inlet velocity are 0.032 m/s, 0.063 m/s, 0.094 m/s and 0.126 m/s. The total pressure drop produce by basic, modified filter 1 and 2 is 292.3 Pa, 251.11 Pa and 274.7 Pa. The pressure drop reduction for the modified filter 1 is 41.19 Pa and 14.1% lower compared to basic filter and the pressure drop reduction for modified filter 2 is 17.6 Pa and 6.02% lower compared to the basic filter. The pressure drops for the basic filter are slightly different with the Salutary Avenue filter due to limited data and experiment details. CFD software are very reliable in running a simulation rather than produces the prototypes and conduct the experiment thus reducing overall time and cost in this study.

  14. Two-phase heat transfer and pressure drop of LNG during saturated flow boiling in a horizontal tube

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Shi, Yumei

    2013-12-01

    Two-phase heat transfer and pressure drop of LNG (liquefied natural gas) have been measured in a horizontal smooth tube with an inner diameter of 8 mm. The experiments were conducted at inlet pressures from 0.3 to 0.7 MPa with a heat flux of 8-36 kW m-2, and mass flux of 49.2-201.8 kg m-2 s-1. The effect of vapor quality, inlet pressure, heat flux and mass flux on the heat transfer characteristic are discussed. The comparisons of the experimental data with the predicted value by existing correlations are analyzed. Zou et al. (2010) correlation shows the best accuracy with 24.1% RMS deviation among them. Moreover four frictional pressure drop methods are also chosen to compare with the experimental database.

  15. Spacecraft compartment venting

    NASA Astrophysics Data System (ADS)

    Scialdone, John J.

    1998-10-01

    At various times, concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

  16. Spacecraft Compartment Venting

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.

    1998-01-01

    At various time concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

  17. Meteorological influence on the occurrence of gastric dilatation-volvulus in military working dogs in Texas.

    PubMed

    Moore, George E; Levine, Michael; Anderson, Johnna D; Trapp, Robert J

    2008-01-01

    Gastric dilatation-volvulus (GDV) is a life-threatening condition in dogs and other species in which the stomach dilates and rotates on itself. The etiology of the disease is multi-factorial, but explicit precipitating causes are unknown. This study sought to determine if there was a significant association between changes in hourly-measured temperature and/or atmospheric pressure and the occurrence of GDV in the population of high-risk working dogs in Texas. The odds of a day being a GDV day, given certain temperature and atmospheric pressure conditions for that day or the day before, was estimated using logistic regression models. There were 57 days in which GDV(s) occurred, representing 2.60% of the days in the 6-year study period. The months of November, December, and January collectively accounted for almost half (47%) of all cases. Disease risk was negatively associated with daily maximum temperature. An increased risk of GDV was weakly associated with the occurrence of large hourly drops in temperature that day and of higher minimum barometric pressure that day and the day before GDV occurrence, but extreme changes were not predictive of the disease.

  18. Meteorological influence on the occurrence of gastric dilatation-volvulus in military working dogs in Texas

    NASA Astrophysics Data System (ADS)

    Moore, George E.; Levine, Michael; Anderson, Johnna D.; Trapp, Robert J.

    2008-01-01

    Gastric dilatation-volvulus (GDV) is a life-threatening condition in dogs and other species in which the stomach dilates and rotates on itself. The etiology of the disease is multi-factorial, but explicit precipitating causes are unknown. This study sought to determine if there was a significant association between changes in hourly-measured temperature and/or atmospheric pressure and the occurrence of GDV in the population of high-risk working dogs in Texas. The odds of a day being a GDV day, given certain temperature and atmospheric pressure conditions for that day or the day before, was estimated using logistic regression models. There were 57 days in which GDV(s) occurred, representing 2.60% of the days in the 6-year study period. The months of November, December, and January collectively accounted for almost half (47%) of all cases. Disease risk was negatively associated with daily maximum temperature. An increased risk of GDV was weakly associated with the occurrence of large hourly drops in temperature that day and of higher minimum barometric pressure that day and the day before GDV occurrence, but extreme changes were not predictive of the disease.

  19. Materials Approach to Fuel Efficient Tires

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Votruba-Drzal, Peter; Kornish, Brian

    2015-06-30

    The objective of this project was to design, develop, and demonstrate fuel efficient and safety regulation compliant tire filler and barrier coating technologies that will improve overall fuel efficiency by at least 2%. The program developed and validated two complementary approaches to improving fuel efficiency through tire improvements. The first technology was a modified silica-based product that is 15% lower in cost and/or enables a 10% improvement in tread wear while maintaining the already demonstrated minimum of 2% improvement in average fuel efficiency. The second technology was a barrier coating with reduced oxygen transmission rate compared to the state-of-the-art halobutylmore » rubber inner liners that will provide extended placarded tire pressure retention at significantly reduced material usage. A lower-permeance, thinner inner liner coating which retains tire pressure was expected to deliver the additional 2% reduction in fleet fuel consumption. From the 2006 Transportation Research Board Report1, a 10 percent reduction in rolling resistance can reduce consumer fuel expenditures by 1 to 2 percent for typical vehicles. This savings is equivalent to 6 to 12 gallons per year. A 1 psi drop in inflation pressure increases the tire's rolling resistance by about 1.4 percent.« less

  20. Improving the result of forcasting using reservoir and surface network simulation

    NASA Astrophysics Data System (ADS)

    Hendri, R. S.; Winarta, J.

    2018-01-01

    This study was aimed to get more representative results in production forcasting using integrated simulation in pipeline gathering system of X field. There are 5 main scenarios which consist of the production forecast of the existing condition, work over, and infill drilling. Then, it’s determined the best development scenario. The methods of this study is Integrated Reservoir Simulator and Pipeline Simulator so-calle as Integrated Reservoir and Surface Network Simulation. After well data result from reservoir simulator was then integrated with pipeline networking simulator’s to construct a new schedule, which was input for all simulation procedure. The well design result was done by well modeling simulator then exported into pipeline simulator. Reservoir prediction depends on the minimum value of Tubing Head Pressure (THP) for each well, where the pressure drop on the Gathering Network is not necessary calculated. The same scenario was done also for the single-reservoir simulation. Integration Simulation produces results approaching the actual condition of the reservoir and was confirmed by the THP profile, which difference between those two methods. The difference between integrated simulation compared to single-modeling simulation is 6-9%. The aimed of solving back-pressure problem in pipeline gathering system of X field is achieved.

  1. Acoustic forcing of a liquid drop

    NASA Technical Reports Server (NTRS)

    Lyell, M. J.

    1992-01-01

    The development of systems such as acoustic levitation chambers will allow for the positioning and manipulation of material samples (drops) in a microgravity environment. This provides the capability for fundamental studies in droplet dynamics as well as containerless processing work. Such systems use acoustic radiation pressure forces to position or to further manipulate (e.g., oscillate) the sample. The primary objective was to determine the effect of a viscous acoustic field/tangential radiation pressure forcing on drop oscillations. To this end, the viscous acoustic field is determined. Modified (forced) hydrodynamic field equations which result from a consistent perturbation expansion scheme are solved. This is done in the separate cases of an unmodulated and a modulated acoustic field. The effect of the tangential radiation stress on the hydrodynamic field (drop oscillations) is found to manifest as a correction to the velocity field in a sublayer region near the drop/host interface. Moreover, the forcing due to the radiation pressure vector at the interface is modified by inclusion of tangential stresses.

  2. Heat transfer and pressure drop measurements in an air/molten salt direct-contact heat exchanger

    NASA Astrophysics Data System (ADS)

    Bohn, Mark S.

    1988-11-01

    This paper presents a comparison of experimental data with a recently published model of heat exchange in irrigated packed beds. Heat transfer and pressure drop were measured in a 150 mm (ID) column with a 610 mm bed of metal Pall rings. Molten nitrate salt and preheated air were the working fluids with a salt inlet temperature of approximately 440 C and air inlet temperatures of approximately 230 C. A comparison between the experimental data and the heat transfer model is made on the basis of heat transfer from the salt. For the range of air and salt flow rates tested, 0.3 to 1.2 kg/sq m/s air flow and 6 to 18 kg/sq m/s salt flow, the data agree with the model within 22 percent standard deviation. In addition, a model for the column pressure drop was validated, agreeing with the experimental data within 18 percent standard deviation over the range of column pressure drop from 40 to 1250 Pa/m.

  3. Operational durability of a giant ER valve for Braille display

    NASA Astrophysics Data System (ADS)

    Luning, Xu; Han, Li; Yufei, Li; Shen, Rong; Kunquan, Lu

    2017-05-01

    The compact configuration of giant ER (electrorheological) valves provides the possibility of realizing a full-page Braille display. The operational durability of ER valves is a key issue in fulfilling a Braille display. A giant ER valve was used to investigate the variations in pressure drops and critical pressure drops of the valves over a long period under some typical operational parameters. The results indicate that neither the pressure drops nor critical pressure drops of giant ER valves show apparent deterioration over a long period. Without ER fluid exchange, a blockage appears in the channel of the valve because the ER structures induced by an external electric field cannot be broken by the Brownian motion of hydraulic oil molecules when the external electric field is removed. Forcing ER fluid flow is an effective and necessary method to keep the channel of the valve unblocked. Thus the operational durability of the valve using giant ER fluids is able to meet the demands of Braille display.

  4. Flow and Thermal Performance of a Water-Cooled Periodic Transversal Elliptical Microchannel Heat Sink for Chip Cooling.

    PubMed

    Wei, Bo; Yang, Mo; Wang, Zhiyun; Xu, Hongtao; Zhang, Yuwen

    2015-04-01

    Flow and thermal performance of transversal elliptical microchannels were investigated as a passive scheme to enhance the heat transfer performance of laminar fluid flow. The periodic transversal elliptical micro-channel is designed and its pressure drop and heat transfer characteristics in laminar flow are numerically investigated. Based on the comparison with a conventional straight micro- channel having rectangular cross section, it is found that periodic transversal elliptical microchannel not only has great potential to reduce pressure drop but also dramatically enhances heat transfer performance. In addition, when the Reynolds number equals to 192, the pressure drop of the transversal elliptical channel is 36.5% lower than that of the straight channel, while the average Nusselt number is 72.8% higher; this indicates that the overall thermal performance of the periodic transversal elliptical microchannel is superior to the conventional straight microchannel. It is suggested that such transversal elliptical microchannel are attractive candidates for cooling future electronic chips effectively with much lower pressure drop.

  5. A study of pressure losses in residential air distribution systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abushakra, Bass; Walker, Iain S.; Sherman, Max H.

    2002-07-01

    An experimental study was conducted to evaluate the pressure drop characteristics of residential duct system components that are either not available or not thoroughly (sometimes incorrectly) described in existing duct design literature. The tests were designed to imitate cases normally found in typical residential and light commercial installations. The study included three different sizes of flexible ducts, under different compression configurations, splitter boxes, supply boots, and a fresh air intake hood. The experimental tests conformed to ASHRAE Standard 120P--''Methods of Testing to Determine Flow Resistance of HVAC Air Ducts and Fittings''. The flexible duct study covered compressibility and bending effectsmore » on the total pressure drop, and the results showed that the available published references tend to underestimate the effects of compression in flexible ducts that can increase pressure drops by up to a factor of nine. The supply boots were tested under different configurations including a setup where a flexible duct elbow connection was considered as an integral part of the supply boot. The supply boots results showed that diffusers can increase the pressure drop by up to a factor of two in exit fittings, and the installation configuration can increase the pressure drop by up to a factor of five. The results showed that it is crucial for designers and contractors to be aware of the compressibility effects of the flexible duct, and the installation of supply boots and diffusers.« less

  6. Analysis of Skylab IV fluid mechanic science demonstration

    NASA Technical Reports Server (NTRS)

    Klett, M. G.; Bourgeois, S. V.

    1975-01-01

    Several science demonstrations performed on Skylab III and IV were concerned with the behavior of fluid drops free floating in microgravity. These demonstrations, with large liquid drops, included the oscillation, rotation, impact and coalescence, and air injection into the drops. Rayleigh's analysis of the oscillation of spherical drops of a liquid predicts accurately the effect of size and surface tension on the frequency of vibrated water globules in the Skylab demonstration. However, damping occurred much faster than predicted by Lamb's or Scriven's analyses of the damping time for spherical drops. The impact demonstrations indicated that a minimum velocity is necessary to overcome surface forces and effect a coalescence, but a precise criterion for the coalescence of liquids in low g could not be determined.

  7. Initial drop size and velocity distributions for airblast coaxial atomizers

    NASA Technical Reports Server (NTRS)

    Eroglu, H.; Chigier, N.

    1991-01-01

    Phase Doppler measurements were used to determine initial drop size and velocity distributions after a complete disintegration of coaxial liquid jets. The Sauter mean diameter (SMD) distribution was found to be strongly affected by the structure and behavior of the preceding liquid intact jet. The axial measurement stations were determined from the photographs of the coaxial liquid jet at very short distances (1-2 mm) downstream of the observed break-up locations. Minimum droplet mean velocities were found at the center, and maximum velocities were near the spray boundary. Size-velocity correlations show that the velocity of larger drops did not change with drop size. Drop rms velocity distributions have double peaks whose radial positions coincide with the maximum mean velocity gradients.

  8. A Validated All-Pressure Fluid Drop Model and Lewis Number Effects for a Binary Mixture

    NASA Technical Reports Server (NTRS)

    Harstad, K.; Bellan, J.

    1999-01-01

    The differences between subcritical liquid drop and supercritical fluid drop behavior are discussed. Under subcritical, evaporative high emission rate conditions, a film layer is present in the inner part of the drop surface which contributes to the unique determination of the boundary conditions; it is this film layer which contributes to the solution's convective-diffusive character. In contrast, under supercritical condition as the boundary conditions contain a degree of arbitrariness due to the absence of a surface, and the solution has then a purely diffusive character. Results from simulations of a free fluid drop under no-gravity conditions are compared to microgravity experimental data from suspended, large drop experiments at high, low and intermediary temperatures and in a range of pressures encompassing the sub-and supercritical regime. Despite the difference between the conditions of the simulations and experiments (suspension vs. free floating), the time rate of variation of the drop diameter square is remarkably well predicted in the linear curve regime. The drop diameter is determined in the simulations from the location of the maximum density gradient, and agrees well with the data. It is also shown that the classical calculation of the Lewis number gives qualitatively erroneous results at supercritical conditions, but that an effective Lewis number previously defined gives qualitatively correct estimates of the length scales for heat and mass transfer at all pressures.

  9. Predicting pressure drop in venturi scrubbers with artificial neural networks.

    PubMed

    Nasseh, S; Mohebbi, A; Jeirani, Z; Sarrafi, A

    2007-05-08

    In this study a new approach based on artificial neural networks (ANNs) has been used to predict pressure drop in venturi scrubbers. The main parameters affecting the pressure drop are mainly the gas velocity in the throat of venturi scrubber (V(g)(th)), liquid to gas flow rate ratio (L/G), and axial distance of the venturi scrubber (z). Three sets of experimental data from five different venturi scrubbers have been applied to design three independent ANNs. Comparing the results of these ANNs and the calculated results from available models shows that the results of ANNs have a better agreement with experimental data.

  10. Development of a constant surface pressure penetration langmuir balance based on axisymmetric drop shape analysis.

    PubMed

    Wege, H A; Holgado-Terriza, J A; Cabrerizo-Vílchez, M A

    2002-05-15

    A new constant pressure pendant-drop penetration surface balance has been developed combining a pendant-drop surface balance, a rapid-subphase-exchange technique, and a fuzzy logic control algorithm. Beside the determination of insoluble monolayer compression-expansion isotherms, it allows performance of noninvasive kinetic studies of the adsorption of surfactants added to the new subphase onto the free surface and of the adsorption/penetration/reaction of the former onto/into/with surface layers, respectively. The interfacial pressure pi is a fundamental parameter in these studies: by working at constant pi one controls the height of the energy barrier to adsorption/penetration and can select different regimes and steps of the adsorption/penetration process. In our device a solution drop is formed at the tip of a coaxial double capillary, connected to a double microinjector. Drop profiles are extracted from digital drop micrographs and fitted to the equation of capillarity, yielding pi, the drop volume V, and the interfacial area A. pi is varied changing V (and hence A) with the microinjector. Control is based on a case-adaptable modulated fuzzy-logic PID algorithm able to maintain constant pi (or A) under a wide range of experimental conditions. The drop subphase liquid can be exchanged quantitatively by the coaxial capillaries. The adsorption/penetration/reaction kinetics at constant pi are then studied monitoring A(t), i.e., determining the relative area change necessary at each instant to compensate the pressure variation due to the interaction of the surfactant in the subsurface with the surface layer. A fully Windows-integrated program manages the whole setup. Examples of experimental protein adsorption and monolayer penetration kinetics are presented.

  11. Technical Requirements for On-Site Thermal Desorption of Solid Media Contaminated with Hazardous Chlorinated Organics

    DTIC Science & Technology

    1997-09-18

    scrubbers , detectable dioxin/furans may occur, since dioxin/furans are much more soluble in organics than in water. Carbon adsorption is frequently...air pollution control device is required. Acid gases may be controlled by using a wet or dry scrubber or by using a coated baghouse. Operating...unit: 1. exit treated waste temperature; 2. baghouse pressure drop, venturi pressure drop, or drop in liquid/gas ratio; 3. waste feed rate; 4

  12. Mechanisms of Exhaust Pollutants and Plume Formation in Continuous Combustion.

    DTIC Science & Technology

    1984-11-30

    drop swirler. A swirled air inlet decreased flame length . Two modes of operation were observed. At higher fuel loadings, reaction could be initiated...and maintained in the recirculation zone in the shadow of the step. The net result was a shorter overall flame length . The low-pressure drop swirler...yielded a shorter flame length relative to the higher pressure drop devices. - • u mmm m -m~amkn Jm• ml AM mmmmm TABLE OF CONTENTS Section Title Page

  13. Visualization Measurement of Streaming Flows Associated with a Single-Acoustic Levitator

    NASA Astrophysics Data System (ADS)

    Hasegawa, Koji; Abe, Yutaka; Kaneko, Akiko; Yamamoto, Yuji; Aoki, Kazuyoshi

    2009-08-01

    The purpose of the study is to experimentally investigate flow fields generated by an acoustic levitator. This flow field has been observed using flow visualization, PIV method. In the absent of a drop, the flow field was strongly influenced by sound pressure level (SPL). In light of the interfacial stability of a levitated drop, SPL was set at 161-163 [dB] in our experiments. In the case of any levitated drop at a pressure node of a standing wave, the toroidal vortices were appeared around a drop and clearly observed the flow fields around the drop by PIV measurement. It is found that the toroidal vortices around a levitated drop were strongly affected by the viscosity of a drop. For more detailed research, experiments in the reduced gravity were conducted with aircraft parabolic flights. By comparison with experimental results in the earth and reduced gravity, it is also indicated that the configuration of the external flow field around a drop is most likely to be affected by a position of a drop as well.

  14. 40 CFR 63.1659 - Reporting requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... followed and the corrective actions taken. (2) Venturi scrubbers. In addition to the information required... identify the periods when the average hourly pressure drop of venturi scrubbers used to control particulate... of the scrubber pressure drop limit per paragraph (b)(2) of this section. These reports are to be...

  15. Interaction of pressure and momentum driven flows with thin porous media: Experiments and modeling

    NASA Astrophysics Data System (ADS)

    Naaktgeboren, Christian

    Flow interaction with thin porous media arise in a variety of natural and man-made settings. Examples include flow through thin grids in electronics cooling, and NOx emissions reduction by means of ammonia injection grids, pulsatile aquatic propulsion with complex trailing anatomy (e.g., jellyfish with tentacles) and microbursts from thunderstorm activity over dense vegetation, unsteady combustion in or near porous materials, pulsatile jet-drying of textiles, and pulsed jet agitation of clothing for trace contaminant sampling. Two types of interactions with thin porous media are considered: (i) forced convection or pressure-driven flows, where fluid advection is maintained by external forces, and (ii) inertial or momentum-driven flows, in which fluid motion is generated but not maintained by external forces. Forced convection analysis through thin permeable media using a porous continuum approach requires the knowledge of porous medium permeability and form coefficients, K and C, respectively, which are defined by the Hazen-Dupuit-Darcy (HDD) equation. Their determination, however, requires the measurement of the pressure-drop per unit of porous medium length. The pressure-drop caused by fluid entering and exiting the porous medium, however, is not related to the porous medium length. Hence, for situations in which the inlet and outlet pressure-drops are not negligible, e.g., for short porous media, the definition of Kand C via the HDD equation becomes ambiguous. This aspect is investigated analytically and numerically using the flow through a restriction in circular pipe and parallel plates channels as preliminary models. Results show that inlet and outlet pressure-drop effects become increasingly important when the inlet and outlet fluid surface fraction φ decreases and the Reynolds number Re increases for both laminar and turbulent flow regimes. A conservative estimate of the minimum porous medium length beyond which the core pressure-drop predominates over the inlet and outlet pressure-drop is obtained by considering a least restrictive porous medium core. Finally, modified K and C are proposed and predictive equations, accurate to within 2.5%, are obtained for both channel configurations with Re ranging from 10-2 to 102 and φ from 6% to 95%. When momentum driven flows interact with thin porous media, the interaction of vortices with the media's complex structure gives way to a number of phenomena of fundamental and applied interest, such as unsteady flow separation. A special case that embodies many of the key features of these flows is the interaction of a vortex ring with a permeable flat surface. Although fundamental, this complex flow configuration has never been considered. The present investigation experimentally studies the fluid mechanics of the interaction of a vortex ring impinging directly on thin permeable flat targets. The vortex ring is formed in water using a piston-cylinder mechanism and visualized using planar laser-induced fluorescence (PLIF). The rings are formed for jet Reynolds numbers of 3000 and 6000, and piston stroke-to-diameter ratios of 1.0, 3.0, and 6.0. Thin screens of similar geometry having surface opening fractions of 44, 60, 69, and 79% are targeted by the rings. The flow that emerges downstream of the screens reforms into a new, "transmitted" vortex ring. For the lower porosity targets, features that are characteristic of vortex ring impingement on walls are also observed, such as primary vortex ring rebound and reversal, flow separation, formation of secondary vortices and mixing. As the interaction proceeds, however, the primary vortex ring and secondary vortices are drawn toward the symmetry axis of the flow by fluid passing through the permeable screen. Quantitative flow measurements using digital particle image velocimetry (DPIV), indicate the transmitted vortex ring has lower velocity and less (total) kinetic energy than the incident ring. Ring trajectories and total kinetic energy relationships between vortices upstream and downstream the porous targets as a function of the porosity are presented, based on the velocity field from the DPIV measurements. Results show that kinetic energy dissipation is more intense for the low porosity targets and that flows with higher initial kinetic energy impacting on the same target loose a smaller percentage of their initial energy.

  16. Optimizing Drilling Efficiency by PWD (Pressure-While-Drilling) Sensor in wells which were drilled in the Khazar-Caspian Sea of the Azerbaijan Republic

    NASA Astrophysics Data System (ADS)

    Amirov, Elnur

    2017-04-01

    Sperry Drilling Services' PWD sensor improve and support drilling efficiency by providing very important, real-time downhole pressure information that allows to make faster and better drilling decisions. The PWD service, provides accurate annular pressure, internal pressure and temperature measurements using any of well-known telemetry systems: positive mud pulse, negative mud pulse and electromagnetic. Pressure data can be transmitted in real time and recorded in downhole memory. In the pumpsoff mode, the minimum, maximum and average pressures observed during the non-circulating period are transmitted via mud pulse telemetry when circulation recommences. These measurements provide the knowledge to avoid lost circulation and detect flow/kicks before they happen. The PWD sensor also reduces the risk of problems related by unexpected fracture or collapse. Sperry's PWD sensor also helps to avoid lost circulation and flow/kick, which can lead to costly delays in drilling. Annular pressure increases often reflect ineffective cuttings removal and poor hole cleaning, both of which can lead to lost circulation. The PWD sensor detects the increase and drilling fluid parameters and operating procedures can be modified to improve hole-cleaning efficiency. On extended reach wells, real-time information helps to maintain wellbore pressures between safe operating limits and to monitor hole cleaning. The PWD sensor also provides early detection of well flows and kicks. A drop in pressure, can indicate gas, oil and water kicks. Because the sensor is making its measurement downhole, the PWD sensor makes it possible to detect such pressure drops earlier than more traditional surface measurements. The PWD sensor has high-accuracy quartz gauges and is able to record data because of its battery-powered operation. It is also extremely useful in specialized drilling environments, such as high-pressure/high-temperature, extended-reach and deepwater wells. When combined with the rig management system, surface and downhole measurements, can be compared for more accurate and extensive analysis. PWD sensor was utilized with encouraging results in many wells up to 3000-6000m subsurface reservoirs (these wells were drilled in the Khazar-Caspian region of the Azerbaijan Republic) and acquired PWD RT/RM data implemented for best drilling practices in other brand new drilled offset wells in order to help us achieve our mission to drill safe, faster, on target, optimize drilling efficiency, maximize well value and reservoir insight.

  17. Electrostatic attraction of charged drops of water inside dropwise cluster

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shavlov, A. V.; Tyumen State Oil and Gas University, 38, Volodarskogo Str., Tyumen 625000; Dzhumandzhi, V. A.

    2013-08-15

    Based on the analytical solution of the Poisson-Boltzmann equation, we demonstrate that inside the electrically neutral system of charges an electrostatic attraction can occur between the like-charged particles, where charge Z ≫ 1 (in terms of elementary charge) and radius R > 0, whereas according to the literature, only repulsion is possible inside non-electrically neutral systems. We calculate the free energy of the charged particles of water inside a cluster and demonstrate that its minimum is when the interdroplet distance equals several Debye radii defined based on the light plasma component. The deepest minimum depth is in a cluster withmore » close spatial packing of drops by type, in a face-centered cubic lattice, if almost all the electric charge of one sign is concentrated on the drops and that of the other sign is concentrated on the light compensation carriers of charge, where the charge moved by equilibrium carriers is rather small.« less

  18. Postprandial hypotension among older residents of a nursing home in Korea.

    PubMed

    Son, Jung Tae; Lee, Eunjoo

    2012-12-01

    The purpose of this study was to identify changes in blood pressure and pulse rate after a meal for elders living in a nursing home. Postprandial hypotension is a major health issue for older persons, because it has been shown to cause increased incidence of falls, syncope, coronary disease, strokes and deterioration in the quality of life. However, there has been little systematic investigation into blood pressure changes after meals in older people. A descriptive, cross-sectional design was used to identify postprandial blood pressure and pulse rate changes in residents of a nursing home. Blood pressure and pulse rates of 121 people aged 65 and above were measured before and after a meal and at 15-minute intervals for six more measurements. Data were analysed with descriptive statistics, repeated measures anova and paired t-tests using SPSS (SPSS Inc., Chicago, IL, USA). There were significant differences in systolic and diastolic pressure by time. The biggest drop in systolic and diastolic blood pressure occurred at 45 minutes after the meal. There was no significant change in pulse rates except for immediately after the meal. To prevent complications from drops in postprandial blood pressure, nurses should carefully monitor blood pressure of elders at least from 30-90 minutes after meals. Further study of drops in postprandial blood pressure should be conducted for various types and times of meals. Nurses caring for older persons can identify drops in the postprandial blood pressure to manage the incidence of falls, syncope and stroke more effectively, especially in nursing homes. © 2012 Blackwell Publishing Ltd.

  19. Calculation of pressure drop in the developmental stages of the medaka fish heart and microvasculature

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sreyashi; Vlachos, Pavlos

    2016-11-01

    Peristaltic contraction of the developing medaka fish heart produces temporally and spatially varying pressure drop across the atrioventricular (AV) canal. Blood flowing through the tail vessels experience a slug flow across the developmental stages. We have performed a series of live imaging experiments over 14 days post fertilization (dpf) of the medaka fish egg and cross-correlated the red blood cell (RBC) pattern intensities to obtain the two-dimensional velocity fields. Subsequently we have calculated the pressure field by integrating the pressure gradient in the momentum equation. Our calculations show that the pressure drop across the AV canal increases from 0.8mm Hg during 3dpf to 2.8 mm Hg during 14dpf. We have calculated the time-varying wall shear stress for the blood vessels by assuming a spatially constant velocity magnitude in each vessel. The calculated wall shear stress matches the wall shear stress sensed by human endothelial cells (10-12 dyne/sq. cm). The pressure drop per unit length of the vessel is obtained by doing a control volume analysis of flow in the caudal arteries and veins. The current results can be extended to investigate the effect of the fluid dynamic parameters on the vascular and cardiac morphogenesis.

  20. Drop deformation and breakup in a partially filled horizontal rotating cylinder

    NASA Astrophysics Data System (ADS)

    White, Andrew; Pereira, Caroline; Hyacinthe, Hyaquino; Ward, Thomas

    2014-11-01

    Drop deformation and breakup due to shear flow has been studied extensively in Couette devices as well as in gravity-driven flows. In these cases shear is generated either by the moving wall or the drop's motion. For such flows the drop shape remains unperturbed at low capillary number (Ca), deforms at moderate Ca , and can experience breakup as Ca --> 1 and larger. Here single drops of NaOH(aq) will be placed in a horizontal cylindrical rotating tank partially filled with vegetable oil resulting in 10-2 < Ca <101 . It will be shown that the reactive vegetable oil-NaOH(aq) system, where surfactants are produced in situ by saponification, can yield lower minimum surface tensions and faster adsorption than non-reactive surfactant systems. Oil films between the wall and drop as well as drop shape will be observed as rotation rates and NaOH(aq) concentration are varied. Results will be presented in the context of previous work on bubble and drop shapes and breakup. NSF CBET #1262718.

  1. The President's Veto of the Minimum Wage Bill: Impact on Poor and Minority Workers.

    ERIC Educational Resources Information Center

    Shapiro, Isaac

    Restoration of an adequate minimum wage remains a critical ingredient in efforts to provide income security for poor and minority workers. The experience of recent years indicates that work does not provide economic security for many poor, Black, and Hispanic workers. National and minority unemployment rates have dropped during the economic…

  2. Drop impact on a solid surface at reduced air pressure

    NASA Astrophysics Data System (ADS)

    Langley, Kenneth; Li, E. Q.; Tian, Y. S.; Hicks, P. D.; Thoroddsen, S. T.

    2017-11-01

    When a drop approaches a solid surface at atmospheric pressure, the lubrication pressure within the air forms a dimple in the bottom of the drop resulting in the entrainment of an air disc upon impact. Reducing the ambient air pressure below atmospheric has been shown to suppress splashing and the compression of the intervening air could be significant on the air disc formation; however, to date there have been no experimental studies showing how the entrainment of the air disc is affected by reducing the ambient pressure. Using ultra-high-speed interferometry, at up to 5 Mfps, we investigate droplet impacts onto dry solid surfaces in reduced ambient air pressures with particular interest in what happens as rarified gas effects become important, i.e. when the thickness of the air layer is of the same magnitude as the mean free path of the air molecules. Experimental data will be presented showing novel phenomena and comparisons will be drawn with theoretical models from the literature.

  3. Laser beam micro-milling of nickel alloy: dimensional variations and RSM optimization of laser parameters

    NASA Astrophysics Data System (ADS)

    Ahmed, Naveed; Alahmari, Abdulrahman M.; Darwish, Saied; Naveed, Madiha

    2016-12-01

    Micro-channels are considered as the integral part of several engineering devices such as micro-channel heat exchangers, micro-coolers, micro-pulsating heat pipes and micro-channels used in gas turbine blades for aerospace applications. In such applications, a fluid flow is required to pass through certain micro-passages such as micro-grooves and micro-channels. The fluid flow characteristics (flow rate, turbulence, pressure drop and fluid dynamics) are mainly established based on the size and accuracy of micro-passages. Variations (oversizing and undersizing) in micro-passage's geometry directly affect the fluid flow characteristics. In this study, the micro-channels of several sizes are fabricated in well-known aerospace nickel alloy (Inconel 718) through laser beam micro-milling. The variations in geometrical characteristics of different-sized micro-channels are studied under the influences of different parameters of Nd:YAG laser. In order to have a minimum variation in the machined geometries of each size of micro-channel, the multi-objective optimization of laser parameters has been carried out utilizing the response surface methodology approach. The objective was set to achieve the targeted top widths and depths of micro-channels with minimum degree of taperness associated with the micro-channel's sidewalls. The optimized sets of laser parameters proposed for each size of micro-channel can be used to fabricate the micro-channels in Inconel 718 with minimum amount of geometrical variations.

  4. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2012-10-01 2012-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

  5. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2013-10-01 2013-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

  6. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2014-10-01 2014-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

  7. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... the facepiece shall not fall below atmospheric at inhalation airflows less than 115 liters (4 cubic...

  8. 42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... the facepiece shall not fall below atmospheric at inhalation airflows less than 115 liters (4 cubic...

  9. Evaluation of different diameter arterial tubing and arterial cannulae in simulated neonatal/pediatric cardiopulmonary bypass circuits.

    PubMed

    Wang, Shigang; Rosenthal, Tami; Kunselman, Allen R; Ündar, Akif

    2015-01-01

    The objective of this study is to evaluate three different diameters of arterial tubing and three diameters of arterial cannulae in terms of pressure drop, and hemodynamic energy delivery in simulated neonatal/pediatric cardiopulmonary bypass (CPB) circuits. The CPB circuit consisted of a Terumo Capiox Baby FX05 oxygenator (Terumo Corporation, Tokyo, Japan), arterial tubing (1/4 in, 3/16 in, or 1/8 in × 150 cm), and a Medtronic Bio-Medicus arterial cannula (8, 10, or 12 Fr; Medtronic, Inc., Minneapolis, MN, USA). The pseudo patient's pressure was maintained at 50 mm Hg. The circuit was primed using lactated Ringer's solution and heparinized packed human red blood cells (hematocrit 30%). Trials were conducted at different flow rates and temperatures (35 and 28°C). Flow and pressure data were collected using a custom-based data acquisition system. Using 8 Fr arterial cannula at 500 mL/min, small diameter arterial tubing generated higher circuit pressure (294.6 ± 0.1 mm Hg [1/8 in], 213.5 ± 0.5 mm Hg [3/16 in], 208.4 ± 0.4 mm Hg [1/4 in] at 35°C) and arterial line pressure drop (158.3 ± 0.1 mm Hg [1/8 in], 79.6 ± 0.1 mm Hg [3/16 in], 62.1 ± 0.1 mm Hg [1/4 in] at 35°C). Using 10 Fr arterial cannula at 1000 mL/min, pre-oxygenator pressures were 266.8 ± 0.2 mm Hg (3/16 in) and 248.0 ± 0.3 mm Hg (1/4 in); arterial line pressure drops were 111.6 ± 0.0 mm Hg (3/16 in) and 74.0 ± 0.1 mm Hg (1/4 in) at 35°C. When using 12 Fr arterial cannula at 1500 mL/min, preoxygenator pressures reached 324.4 ± 0.3 mm Hg (3/16 in) and 302.5 ± 0.4 mm Hg (1/4 in); arterial line pressure drops were 154.0 ± 0.1 mm Hg (3/16 in) and 92.0 ± 0.2 mm Hg (1/4 in) at 35°C. Pressure drops across arterial line tubing were main CPB circuit pressure drops. High flow rate, hypothermia, small diameter arterial tubing. and arterial cannula created more hemodynamic energy at the preoxygenator site, but energy loss across CPB circuit also increased. Although small diameter (<1/4 in ID) arterial tubing may decrease total CPB priming volume, it also led to significantly higher circuit pressure, higher pressure drop, and more hemodynamic energy loss across CPB circuit. Larger diameter arterial cannula had less pressure drop and allowed more hemodynamic energy delivery to the patient. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  10. Fundamental study of transpiration cooling. [pressure drop and heat transfer data from porous metals

    NASA Technical Reports Server (NTRS)

    Koh, J. C. Y.; Dutton, J. L.; Benson, B. A.

    1973-01-01

    Isothermal and non-isothermal pressure drop data and heat transfer data generated on porous 304L stainless steel wire forms, sintered spherical stainless steel powder, and sintered spherical OFHC copper powder are reported and correlated. Pressure drop data was collected over a temperature range from 500 R to 2000 R and heat transfer data collected over a heat flux range from 5 to 15 BTU/in2/sec. It was found that flow data could be correlated independently of transpirant temperature and type (i.e., H2, N2). It was also found that no simple relation between heat transfer coefficient and specimen porosity was obtainable.

  11. Orbiter thermal pressure drop characteristics for shuttle orbiter thermal protection system components: High density tile, low density tile, densified low density tile, and strain isolation pad

    NASA Technical Reports Server (NTRS)

    Lawing, P. L.; Nystrom, D. M.

    1980-01-01

    Pressure drop tests were conducted on available samples of low and high density tile, densified low density tile, and strain isolation pads. The results are presented in terms of pressure drop, material thickness and volume flow rate. Although the test apparatus was only capable of a small part of the range of conditions to be encountered in a Shuttle Orbiter flight, the data serve to determine the type of flow characteristics to be expected for each material type tested; the measured quantities also should serve as input for initial venting and flow through analysis.

  12. Condensation of nano-refrigerant inside a horizontal tube

    NASA Astrophysics Data System (ADS)

    Darzi, Milad; Sadoughi, M. K.; Sheikholeslami, M.

    2018-05-01

    In this paper, condensing pressure drop of refrigerant-based nanofluid inside a tube is studied. Isobutene was selected as the base fluid while CuO nanoparticles were utilized to prepare nano-refrigerant. However, for the feasibility of nanoparticle dispersion into the refrigerant, Polyester oil (POE) was utilized as lubricant oil and added to the pure refrigerant by 1% mass fraction. Various values of mass flux, vapor quality, concentration of nanoparticle are investigated. Results indicate that adding nanoparticles leads to enhance frictional pressure drop. Nanoparticles caused larger pressure drop penalty at relatively lower vapor qualities which may be attributed to the existing condensation flow pattern such that annular flow is less influenced by nanoparticles compared to intermittent flow regime.

  13. Flowrate testing of the bag filter LANCS-BOP 6CPVC-1.5-2SPVC (LANCS Industries) at 1 psig

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moore, Murray E.; Currie, Karissa Lyn; Berg, Charlotte Katherine

    2016-09-13

    The air flowrate through a flexible HEPA grade filter (Part LANCS-BOP 6CPVC-1.5-2SPVC www.lancsindustries.com) was measured at 48 ALPM for a differential pressure drop of 1.0 psig (28 inWC, 7.0 kPa). These filters are rated by the manufacturer to have a flowrate of 3 ALPM at a differential pressure drop of 1 inWC (0.25 kPa). The Los Alamos National Laboratory Aerosol Engineering Facility used one of their test rigs (originally developed to measure the pressure drop in capsule HEPA filters) to measure the airflow through the LANCS bag filter.

  14. Combustion of Interacting Droplet Arrays in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    Dietrich, D. L.; Struk, P. M.; Kitano, K.; Ikegami, M.

    1999-01-01

    Investigations into droplet interactions date back to Rex et al. Recently, Annamalai and Ryan and Annamalai published extensive reviews of droplet array and cloud combustion studies. The authors studied the change in the burning rate constant, k, (relative to that of the single droplet) that results from interactions. Under certain conditions, there exists a separation distance where the droplet lifetime reaches a minimum, or average burning rate constant is a maximum . Additionally, since inter-droplet separation distance, L, increases relative to the droplet size, D, as the burning proceeds, the burning rate is not constant throughout the burn, but changes continuously with time. Only Law and co-workers and Mikami et al. studied interactions under conditions where buoyant forces were negligible. Comparing their results with existing theory, Law and co-workers found that theory over predicted the persistency and intensity of droplet interactions. The droplet interactions also depended on the initial array configuration as well as the instantaneous array configuration. They also concluded that droplet heating was retarded due to interactions and that the burning process did not follow the "D-squared" law. Mikami et al. studied the combustion of a two-droplet array of heptane burning in air at one atm pressure in microgravity. They showed that the instantaneous burning rate constant increases throughout the droplet lifetime, even for a single droplet. Also, the burn time of the array reached a minimum at a critical inter-droplet spacing. In this article, we examine droplet interactions in normal and microgravity environments. The microgravity experiments were in the NASA GRC 2.2 and 5.2 second drop towers, and the JAMIC (Japan Microgravity Center) 10 second drop tower. Special emphasis is directed to combustion under conditions that yield finite extinction diameters, and to determine how droplet interactions affect the extinction process.

  15. Rotating diffuser for pressure recovery in a steam cooling circuit of a gas turbine

    DOEpatents

    Eldrid, Sacheverel Q.; Salamah, Samir A.; DeStefano, Thomas Daniel

    2002-01-01

    The buckets of a gas turbine are steam-cooled via a bore tube assembly having concentric supply and spent cooling steam return passages rotating with the rotor. A diffuser is provided in the return passage to reduce the pressure drop. In a combined cycle system, the spent return cooling steam with reduced pressure drop is combined with reheat steam from a heat recovery steam generator for flow to the intermediate pressure turbine. The exhaust steam from the high pressure turbine of the combined cycle unit supplies cooling steam to the supply conduit of the gas turbine.

  16. The Role of Drag Force in Shedding of Multiple Sessile Drops

    NASA Astrophysics Data System (ADS)

    Razzaghi, Aysan; Banitabaei, Sayyed Hossein; Amirfazli, Alidad; -Team

    2017-11-01

    A sessile drop placed on a solid surface can shed, if the drag force due to a shearing airflow overcomes the drop adhesion to the surface. Sessile drop shedding is of importance due to its applications in condensation, fuel cells, icing, etc. Majority of the studies so far have considered the shedding of a single sessile droplet; however, in the applications above, multiple sessile droplets appear on a surface. Shedding of sessile drops in different arrangements, i.e. tandem, side by side, triangle, and rectangle have been investigated both experimentally and through VOF simulations. The minimum air velocity (Ucr) at which the drop(s) at the upstream dislodge from the surface was measured. Drops were placed in a wind tunnel with increasing air velocity at a rate of 1m/s2. It has been found that Ucr, deviates from its value for a single drop due to presence of the neighboring drops. The amount of the deviation is closely related to the flow pattern and interaction of drop wakes which are elucidated numerically. The interacting wakes change the drag force on the drops. Generally, the adhesion force is not affected by presence of other drops. As such, when the drops' wakes are interacting strongly, Ucr can increase by 45%.

  17. Effects of sudden air pressure changes on hospital admissions for cardiovascular diseases in Prague, 1994-2009

    NASA Astrophysics Data System (ADS)

    Plavcová, Eva; Kyselý, Jan

    2014-08-01

    Sudden weather changes have long been thought to be associated with negative impacts on human health, but relatively few studies have attempted to quantify these relationships. We use large 6-h changes in atmospheric pressure as a proxy for sudden weather changes and evaluate their association with hospital admissions for cardiovascular diseases (CVD). Winter and summer seasons and positive and negative pressure changes are analysed separately, using data for the city of Prague (population 1.2 million) over a 16-year period (1994-2009). We found that sudden pressure drops in winter are associated with significant rise in hospital admissions. Increased CVD morbidity was observed neither for pressure drops in summer nor pressure increases in any season. Analysis of synoptic weather maps shows that large pressure drops in winter are associated with strong zonal flow and rapidly moving low-pressure systems with centres over northern Europe and atmospheric fronts affecting western and central Europe. Analysis of links between passages of strong atmospheric fronts and hospital admissions, however, shows that the links disappear if weather changes are characterised by frontal passages. Sudden pressure drops in winter are associated also with significant excess CVD mortality. As climate models project strengthening of zonal circulation in winter and increased frequency of windstorms, the negative effects of such weather phenomena and their possible changes in a warmer climate of the twenty-first century need to be better understood, particularly as their importance in inducing excess morbidity and mortality in winter may increase compared to cold spells.

  18. 40 CFR 63.11567 - Who implements and enforces this subpart?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Processing and Asphalt Roofing Manufacturing Other Requirements and Information § 63.11567 Who implements and...). 2. A high-efficiency air filter or fiber bed filter a. Inlet gas temperature b, andb. Pressure drop... the inlet gas temperature and pressure drop, you can use a leak detection system that identifies when...

  19. 40 CFR Table 4 of Subpart Aaaaaaa... - Operating Limits

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Roofing Manufacturing Other Requirements and Information Who implements and enforces this subpart? Pt. 63... filter or fiber bed filter a. Inlet gas temperature b, andb. Pressure drop across device b The 3-hour... temperature and pressure drop, you can use a leak detection system that identifies when the filter media has...

  20. 40 CFR Table 4 of Subpart Aaaaaaa... - Operating Limits

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Roofing Manufacturing Other Requirements and Information Who implements and enforces this subpart? Pt. 63... filter or fiber bed filter a. Inlet gas temperature b, andb. Pressure drop across device b The 3-hour... temperature and pressure drop, you can use a leak detection system that identifies when the filter media has...

  1. 40 CFR Table 2 to Subpart Kkkkk of... - Operating Limits

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... Maintain the average scrubber pressure drop for each 3-hour block period at or above the average pressure drop established during the performance test; andb. Maintain the average scrubber liquid pH for each 3-hour block period at or above the average scrubber liquid pH established during the performance test...

  2. Directly Estimating Earthquake Rupture Area using Second Moments to Reduce the Uncertainty in Stress Drop

    NASA Astrophysics Data System (ADS)

    McGuire, Jeffrey J.; Kaneko, Yoshihiro

    2018-06-01

    The key kinematic earthquake source parameters: rupture velocity, duration and area, shed light on earthquake dynamics, provide direct constraints on stress-drop, and have implications for seismic hazard. However, for moderate and small earthquakes, these parameters are usually poorly constrained due to limitations of the standard analysis methods. Numerical experiments by Kaneko and Shearer [2014,2015] demonstrated that standard spectral fitting techniques can lead to roughly 1 order of magnitude variation in stress-drop estimates that do not reflect the actual rupture properties even for simple crack models. We utilize these models to explore an alternative approach where we estimate the rupture area directly. For the suite of models, the area averaged static stress drop is nearly constant for models with the same underlying friction law, yet corner frequency based stress-drop estimates vary by a factor of 5-10 even for noise free data. Alternatively, we simulated inversions for the rupture area as parameterized by the second moments of the slip distribution. A natural estimate for the rupture area derived from the second moments is A=πLcWc, where Lc and Wc are the characteristic rupture length and width. This definition yields estimates of stress drop that vary by only 10% between the models but are slightly larger than the true area-averaged values. We simulate inversions for the second moments for the various models and find that the area can be estimated well when there are at least 15 available measurements of apparent duration at a variety of take-off angles. The improvement compared to azimuthally-averaged corner-frequency based approaches results from the second moments accounting for directivity and removing the assumption of a circular rupture area, both of which bias the standard approach. We also develop a new method that determines the minimum and maximum values of rupture area that are consistent with a particular dataset at the 95% confidence level. For the Kaneko and Shearer models with 20+ randomly distributed observations and ˜10% noise levels, we find that the maximum and minimum bounds on rupture area typically vary by a factor of two and that the minimum stress drop is often more tightly constrained than the maximum.

  3. Heat transfer and pressure drop in rectangular channels with crossing fins (a Review)

    NASA Astrophysics Data System (ADS)

    Sokolov, N. P.; Polishchuk, V. G.; Andreev, K. D.; Rassokhin, V. A.; Zabelin, N. A.

    2015-06-01

    Channels with crossing finning find wide use in the cooling paths of high-temperature gas turbine blade systems. At different times, different institutions carried out experimental investigations of heat transfer and pressure drop in channels with coplanar finning of opposite walls for obtaining semiempirical dependences of Nusselt criteria (dimensionless heat-transfer coefficients) and pressure drop coefficients on the operating Reynolds number and relative geometrical parameters (or their complexes). The shape of experimental channels, the conditions of experiments, and the used variables were selected so that they would be most suited for solving particular practical tasks. Therefore, the results obtained in processing the experimental data have large scatter and limited use. This article considers the results from experimental investigations of different authors. In comparing the results, additional calculations were carried out for bringing the mathematical correlations to the form of dependences from the same variables. Generalization of the results is carried out. In the final analysis, universal correlations are obtained for determining the pressure drop coefficients and Nusselt number values for the flow of working medium in channels with coplanar finning.

  4. Droplet formation and scaling in dense suspensions

    PubMed Central

    Miskin, Marc Z.; Jaeger, Heinrich M.

    2012-01-01

    When a dense suspension is squeezed from a nozzle, droplet detachment can occur similar to that of pure liquids. While in pure liquids the process of droplet detachment is well characterized through self-similar profiles and known scaling laws, we show here the simple presence of particles causes suspensions to break up in a new fashion. Using high-speed imaging, we find that detachment of a suspension drop is described by a power law; specifically we find the neck minimum radius, rm, scales like near breakup at time τ = 0. We demonstrate data collapse in a variety of particle/liquid combinations, packing fractions, solvent viscosities, and initial conditions. We argue that this scaling is a consequence of particles deforming the neck surface, thereby creating a pressure that is balanced by inertia, and show how it emerges from topological constraints that relate particle configurations with macroscopic Gaussian curvature. This new type of scaling, uniquely enforced by geometry and regulated by the particles, displays memory of its initial conditions, fails to be self-similar, and has implications for the pressure given at generic suspension interfaces. PMID:22392979

  5. The long-term performance of electrically charged filters in a ventilation system.

    PubMed

    Raynor, Peter C; Chae, Soo Jae

    2004-07-01

    The efficiency and pressure drop of filters made from polyolefin fibers carrying electrical charges were compared with efficiency and pressure drop for filters made from uncharged glass fibers to determine if the efficiency of the charged filters changed with use. Thirty glass fiber filters and 30 polyolefin fiber filters were placed in different, but nearly identical, air-handling units that supplied outside air to a large building. Using two kinds of real-time aerosol counting and sizing instruments, the efficiency of both sets of filters was measured repeatedly for more than 19 weeks while the air-handling units operated almost continuously. Pressure drop was recorded by the ventilation system's computer control. Measurements showed that the efficiency of the glass fiber filters remained almost constant with time. However, the charged polyolefin fiber filters exhibited large efficiency reductions with time before the efficiency began to increase again toward the end of the test. For particles 0.6 microm in diameter, the efficiency of the polyolefin fiber filters declined from 85% to 45% after 11 weeks before recovering to 65% at the end of the test. The pressure drops of the glass fiber filters increased by about 0.40 in. H2O, whereas the pressure drop of the polyolefin fiber filters increased by only 0.28 in. H2O. The results indicate that dust loading reduces the effectiveness of electrical charges on filter fibers. Copyright 2004 JOEH, LLC

  6. PATHFINDER ATOMIC POWER PLANT. FILTRATION OF ALUMINUM CORROSION PRODUCTS PRODUCED IN HIGH-TEMPERATURE, HIGH PURITY WATER SYSTEMS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Noble, J.H.; Davie, R.L.

    1961-05-01

    Filter tests were conducted to determine the most suitable filter for removing large quantities of aluminum corrosion product (boehmite) from reactor water. Filters tested included the following: wire-wound, sintered filter elements, sintered ceramic fllter elements, cotton stringwound filter elements, felted-cotton filter elements, cation resin, adsorption resin, diatomaceous earth precoat filter, and a wood-cellulose precoat filter. Parameters measured were flow rate, filter-influent and -effluent boehmite concentration, pressure drop, and final filter load. The pressure drop and efficiency of the filters was correlated with boehmite load. Boehmite deposits on filters as a nonporous gelatinous cake, and causes a rapidly increasing pressure drop.more » Tests indicate that the optimum load with filter elements and precoat filters is achieved at a pressure drop of 25 psi. Very little additional load can be obtained by operating to a higher pressure drop. Of the filters tested, the precoat filter snd 40 to 60 mesh cation resin were the more effective in removing boehmite. The efficiency of the precoat filter was in excess of 99%, and the efficiency of the cation resin was for the most part in excess of 95%. For various reasons, the other filters were eliminated from final consideration. The test program and available literature indicated that an element type precoat filter using wood cellulose as the precoat media would be most suitable for the proposed application. (auth)« less

  7. Method for Hot Real-Time Sampling of Gasification Products

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pomeroy, Marc D

    The Thermochemical Process Development Unit (TCPDU) at the National Renewable Energy Laboratory (NREL) is a highly instrumented half-ton/day pilot scale plant capable of demonstrating industrially relevant thermochemical technologies from lignocellulosic biomass conversion, including gasification. Gasification creates primarily Syngas (a mixture of Hydrogen and Carbon Monoxide) that can be utilized with synthesis catalysts to form transportation fuels and other valuable chemicals. Biomass derived gasification products are a very complex mixture of chemical components that typically contain Sulfur and Nitrogen species that can act as catalysis poisons for tar reforming and synthesis catalysts. Real-time hot online sampling techniques, such as Molecular Beammore » Mass Spectrometry (MBMS), and Gas Chromatographs with Sulfur and Nitrogen specific detectors can provide real-time analysis providing operational indicators for performance. Sampling typically requires coated sampling lines to minimize trace sulfur interactions with steel surfaces. Other materials used inline have also shown conversion of sulfur species into new components and must be minimized. Sample line Residence time within the sampling lines must also be kept to a minimum to reduce further reaction chemistries. Solids from ash and char contribute to plugging and must be filtered at temperature. Experience at NREL has shown several key factors to consider when designing and installing an analytical sampling system for biomass gasification products. They include minimizing sampling distance, effective filtering as close to source as possible, proper line sizing, proper line materials or coatings, even heating of all components, minimizing pressure drops, and additional filtering or traps after pressure drops.« less

  8. Distribution and observed associations of orthostatic blood pressure changes in elderly general medicine outpatients

    NASA Technical Reports Server (NTRS)

    Robertson, D.; DesJardin, J. A.; Lichtenstein, M. J.

    1998-01-01

    Factors associated with orthostatic blood pressure change in elderly outpatients were determined by surveying 398 medical clinical outpatients aged 65 years and older. Blood pressure was measured with random-zero sphygmomanometers after patients were 5 minutes in a supine and 5 minutes in a standing position. Orthostatic blood pressure changes were at normally distributed levels with systolic and diastolic pressures dropping an average of 4 mm Hg (standard deviation [SD]=15 mm Hg) and 2 mm Hg (SD=11 mm Hg), respectively. Orthostatic blood pressure changes were unassociated with age, race, sex, body mass, time since eating, symptoms, or other factors. According to multiple linear regression analysis, supine systolic pressure, chronic obstructive pulmonary disease (COPD), and diabetes mellitus were associated with a decrease in systolic pressure on standing. Hypertension, antiarthritic drugs, and abnormal heartbeat were associated with an increase in systolic pressure on standing. For orthostatic diastolic pressure changes, supine diastolic pressure and COPD were associated with a decrease in diastolic pressure on standing. Congestive heart failure was associated with an increase in standing diastolic pressure. Using logistic regression analysis, only supine systolic pressure was associated with a greater than 20-mm Hg drop in systolic pressure (n=53, prevalence=13%). Supine diastolic pressure and COPD were the only variables associated with a greater than 20-mm Hg drop in diastolic pressure (n=16, prevalence=4%). These factors may help physicians in identifying older persons at risk for having orthostatic hypotension.

  9. Studies on droplet evaporation and combustion in high pressures

    NASA Technical Reports Server (NTRS)

    Sato, J.

    1993-01-01

    High pressure droplet evaporation and combustion have been studied up to 15 MPa under normal and microgravity fields. From the evaporation studies, it has been found that in the supercritical environments, the droplet evaporation rate and lifetime take a maximum and a minimum at an ambient pressure over the critical pressure. Its maximum and minimum points move toward the lower ambient pressures if the ambient temperature is increased. It has been found from the combustion studies that the burning life time takes a minimum at an ambient pressure being equal to the critical pressure. It is attributable to both the pressure dependency of the diffusion rate and the droplet evaporation characteristics described above.

  10. Development of a split-flow system for high precision variable sample introduction in supercritical fluid chromatography.

    PubMed

    Sakai, Miho; Hayakawa, Yoshihiro; Funada, Yasuhiro; Ando, Takashi; Fukusaki, Eiichiro; Bamba, Takeshi

    2017-09-15

    In this study, we propose a novel variable sample injection system based on full-loop injection, named the split-flow sample introduction system, for application in supercritical fluid chromatography (SFC). In this system, the mobile phase is split by the differential pressure between two back pressure regulators (BPRs) after full-loop injection suitable for SFC, and this differential pressure determines the introduction rate. Nine compounds with a wide range of characteristics were introduced with high reproducibility and universality, confirming that a robust variable sample injection system was achieved. We also investigated the control factors of our proposed system. Sample introduction was controlled by the ratio between the column-side pressure drops in splitless and split flow, ΔP columnsideinsplitless and ΔP columnsideinsplit , respectively, where ΔP columnsideinsplitless is related to the mobile phase flow rate and composition and the column resistance. When all other conditions are kept constant, increasing the make-up flow induces an additional pressure drop on the column side of the system, which leads to a reduced column-side flow rate, and hence decreased the amount of sample injected, even when the net pressure drop on the column side remains the same. Thus, sample introduction could be highly controlled at low sample introduction rate, regardless of the introduction conditions. This feature is advantageous because, as a control factor, the solvent in the make-up pump is independent of the column-side pressure drop. Copyright © 2017. Published by Elsevier B.V.

  11. Flow structure, heat transfer and pressure drop in varying aspect ratio two-pass rectangular smooth channels

    NASA Astrophysics Data System (ADS)

    Siddique, Waseem; El-Gabry, Lamyaa; Shevchuk, Igor V.; Hushmandi, Narmin B.; Fransson, Torsten H.

    2012-05-01

    Two-pass channels are used for internal cooling in a number of engineering systems e.g., gas turbines. Fluid travelling through the curved path, experiences pressure and centrifugal forces, that result in pressure driven secondary motion. This motion helps in moving the cold high momentum fluid from the channel core to the side walls and plays a significant role in the heat transfer in the channel bend and outlet pass. The present study investigates using Computational Fluid Dynamics (CFD), the flow structure, heat transfer enhancement and pressure drop in a smooth channel with varying aspect ratio channel at different divider-to-tip wall distances. Numerical simulations are performed in two-pass smooth channel with aspect ratio Win/H = 1:3 at inlet pass and Wout/H = 1:1 at outlet pass for a variety of divider-to-tip wall distances. The results show that with a decrease in aspect ratio of inlet pass of the channel, pressure loss decreases. The divider-to-tip wall distance (Wel) not only influences the pressure drop, but also the heat transfer enhancement at the bend and outlet pass. With an increase in the divider-to-tip wall distance, the areas of enhanced heat transfer shifts from side walls of outlet pass towards the inlet pass. To compromise between heat transfer and pressure drop in the channel, Wel/H = 0.88 is found to be optimum for the channel under study.

  12. Design of distributed JT (Joule-Thomson) effect heat exchanger for superfluid 2 K cooling device

    NASA Astrophysics Data System (ADS)

    Jeong, S.; Park, C.; Kim, K.

    2018-03-01

    Superfluid at 2 K or below is readily obtained from liquid helium at 4.2 K by reducing its vapour pressure. For better cooling performance, however, the cold energy of vaporized helium at 2 K chamber can be effectively utilized in a recuperator which is specially designed in this paper for accomplishing so-called the distributed Joule-Thomson (JT) expansion effect. This paper describes the design methodology of distributed JT effect heat exchanger for 2 K JT cooling device. The newly developed heat exchanger allows continuous significant pressure drop at high-pressure part of the recuperative heat exchanger by using a capillary tube. Being different from conventional recuperative heat exchangers, the efficient JT effect HX must consider the pressure drop effect as well as the heat transfer characteristic. The heat exchanger for the distributed JT effect actively utilizes continuous pressure loss at the hot stream of the heat exchanger by using an OD of 0.64 mm and an ID of 0.4 mm capillary tube. The analysis is performed by dividing the heat exchanger into the multiple sub-units of the heat exchange part and JT valve. For more accurate estimation of the pressure drop of spirally wound capillary tube, preliminary experiments are carried out to investigate the friction factor at high Reynolds number. By using the developed pressure drop correlation and the heat transfer correlation, the specification of the heat exchanger with distributed JT effect for 2 K JT refrigerator is determined.

  13. Fuel cell flooding detection and correction

    DOEpatents

    DiPierno Bosco, Andrew; Fronk, Matthew Howard

    2000-08-15

    Method and apparatus for monitoring an H.sub.2 -O.sub.2 PEM fuel cells to detect and correct flooding. The pressure drop across a given H.sub.2 or O.sub.2 flow field is monitored and compared to predetermined thresholds of unacceptability. If the pressure drop exists a threshold of unacceptability corrective measures are automatically initiated.

  14. Sound wave energy emitted by water drop during the splash on the soil surface

    NASA Astrophysics Data System (ADS)

    Bieganowski, Andrzej; Ryżak, Magdalena; Korbiel, Tomasz

    2017-04-01

    A drop of rain falling on the surface of bare soil not only moisturizes but also can cause splash or compaction, depending on the energy of incident drops and the condition of the surface on which it falls. The splash phenomenon can be characterized by the weight of detached soil material (using splash cups) as well as the number and trajectory of splashed particles (using high-speed cameras). The study presents a new aspect of the analysis of the splash phenomenon by measurement of the sound pressure level and the sound energy of the wave that propagates in the air. The measurements were carried out in an anechoic chamber. Three soils (Endogleyic Umbrisol, Fluvic Endogleyic Cambisol, and Haplic Chernozem) with four initial moisture levels (pressure heads: 0.1 kPa, 1 kPa, 3.16 kPa, and 16 kPa) were tested. Drops of 4.2 mm diameter were falling from a height of 1.5m. The sound pressure level was recorded after 10 consecutive water drop impacts using a special set of microphones. In all measuring conditions with 1m distance, the sound pressure level ranged from 27 to 42dB. The impact of water drops on the ground created sound pulses, which were recalculated to the energy emitted in the form of sound waves. For all soil samples, the sound wave energy was within the range of 0.14 μJ to 5.26 μJ, which corresponds to 0.03-1.07% of the energy of the incident drops (Ryżak et al., 2016). This work was partly financed from the National Science Centre, Poland; project no. 2014/14/E/ST10/00851. References Ryżak M., Bieganowski A., Korbiel T.: Sound wave Energy resulting from the impact of water drops on the soil surface. PLoS One 11(7):e0158472. doi:10.1371/journal.pone.0158472, 2016

  15. The effect of geometry and operation conditions on the performance of a gas-liquid cylindrical cyclone separator with new structure

    NASA Astrophysics Data System (ADS)

    Han, Qing; Zhang, Chi; Xu, Bo; Chen, Jiangping

    2013-07-01

    The hydrodynamic flow behavior, effects of geometry and working conditions of a gas-liquid cylindrical cyclone separator with a new structure are investigated by computational fluid dynamic and experiment. Gas liquid cylindrical cyclone separator is widely used in oil industry, refrigeration system because of its simple structure, high separating efficiency, little maintenance and no moving parts nor internal devices. In this work, a gas liquid cylindrical cyclone separator with new structure used before evaporator in refrigeration system can remove the vapor from the mixture and make evaporator compact by improving its heat exchange efficiency with the lower inlet quality. It also decreases evaporator pressure drop and reduces compressor work. The two pipes are placed symmetrically which makes each of them can be treated as inlet. It means when the fluids flow reverse, the separator performance will not be influence. Four samples with different geometry parameters are tested by experiment with different inlet quality (0.18-0.33), inlet mass flow rate (65-100kg/h). Compared with the experimental data, CFD simulation results show a good agreement. Eulerian multiphase model and Reynolds Stress Turbulence model are applied in the CFD simulation and obtained the inner flow field such as phase path lines, tangential velocity profiles and pressure and volume of fraction distribution contours. The separator body diameter (24, 36, 48mm) and inlet diameter (3.84, 4.8, 5.76mm) decide the maximum tangential velocity which results in the centrifugal force. The tangential velocity profiles are simulated and compared among different models. The higher tangential velocity makes higher quality of gas outlet but high pressure drop at the same time. Decreasing the inlet diameter increases quality of gas outlet pipe and pressure drop. High gas outlet quality is cost at high pressure drop. Increasing of separator diameter makes gas outlet quality increase first and then decrease but the pressure drop decreases all the way. The offset (0, 2.4, 3.6mm) of gas outlet is an insensitive factor which influences the quality and pressure drop little.

  16. Development of a test facility and preliminary testing of flow boiling heat transfer of R410A refrigerant with Al2O3 nanolubricants

    NASA Astrophysics Data System (ADS)

    Wong, Thiam

    In vapor compression cycles, a small portion of the oil circulates with the refrigerant throughout the system components, while most of the oil stays in the compressors. In heat exchangers, the lubricant in excess penalizes the heat transfer and increases the pressure losses: both effects are highly undesired but yet unavoidable. Nanoparticles dispersed in the excess lubricant are expected to provide enhancements in heat transfer. While solubility and miscibility of refrigerants in polyolesters (POE) lubricant are well established knowledge, there is a lack of information regarding if and how nanoparticles dispersed in the lubricant affect these properties. This thesis presents experimental data of solubility of two types of Al2O3 nanolubricants with refrigerant R-410A. The nanoparticles were dispersed in POE lubricant by using different surfactants and dispersion methods. The nanolubricants appeared to have slightly lower solubility than that of R-410A but actually the solid nanoparticles did not really interfere with the POE oil solubility characteristics. A test facility and experimental methodology was developed for the investigation of heat transfer coefficient and pressure drop. The pressure drop of the refrigerant lubricant mixtures during flow boiling depended on the mass flux of the refrigerant. Greater augmentation was seen in the pressure drop results with decreasing mass flow rate. Pure refrigerant R410A showed the lowest pressure drop, addition of nanolubricants to the refrigerant showed a slightly higher pressure drop and POE-refrigerant mixture showed the highest pressure drop in the tests conducted. Enhancement or degradation in heat transfer coefficient during flow boiling depended on the nanoparticle concentration in the lubricant as well as the lubricant concentration in refrigerant. R410A showed the highest heat transfer coefficient for all conditions tested. For a concentration of 1% nanolubricant in refrigerant, the heat transfer coefficient showed more enhancement with increase in nanoparticle concentration compared to POE refrigerant mixtures. For a concentration of 3% nanolubricant in refrigerant mixtures there was little to no enhancement for tests conducted.

  17. Pressure-Drop Considerations in the Characterization of Dew-Point Transfer Standards at High Temperatures

    NASA Astrophysics Data System (ADS)

    Mitter, H.; Böse, N.; Benyon, R.; Vicente, T.

    2012-09-01

    During calibration of precision optical dew-point hygrometers (DPHs), it is usually necessary to take into account the pressure drop induced by the gas flow between the "point of reference" and the "point of use" (mirror or measuring head of the DPH) either as a correction of the reference dew-point temperature or as part of the uncertainty estimation. At dew-point temperatures in the range of ambient temperature and below, it is sufficient to determine the pressure drop for the required gas flow, and to keep the volumetric flow constant during the measurements. In this case, it is feasible to keep the dry-gas flow into the dew-point generator constant or to measure the flow downstream the DPH at ambient temperature. In normal operation, at least one DPH in addition to the monitoring DPH are used, and this operation has to be applied to each instrument. The situation is different at high dew-point temperatures up to 95 °C, the currently achievable upper limit reported in this paper. With increasing dew-point temperatures, the reference gas contains increasing amounts of water vapour and a constant dry-gas flow will lead to a significant enhanced volume flow at the conditions at the point of use, and therefore, to a significantly varying pressure drop depending on the applied dew-point temperature. At dew-point temperatures above ambient temperature, it is also necessary to heat the reference gas and the mirror head of the DPH sufficiently to avoid condensation which will additionally increase the volume flow and the pressure drop. In this paper, a method is provided to calculate the dry-gas flow rate needed to maintain a known wet-gas flow rate through a chilled mirror for a range of temperature and pressures.

  18. Axisymmetric oscillation modes of a double droplet system

    DOE PAGES

    Ramalingam, Santhosh K.; Basaran, Osman A.

    2010-11-15

    A double droplet system (DDS) consists of a sessile and a pendant drop that are coupled through a liquid filled cylindrical hole in a plate of thickness d. For a small hole radius R, equilibrium shapes of both drops are sections of spheres. While DDSs have a number of applications in microfluidics, a DDS oscillating about its equilibrium state can be used as a fast focusing liquid lens. Here, a DDS consisting of an isothermal, incompressible Newtonian fluid of constant density p and constant viscosity u that is surrounded by a gas is excited by oscillating in time (a) themore » pressure in the gas surrounding either drop (pressure excitation), (b) the plate perpendicular to its plane (axial excitation), and (c) the hole radius (radial excitation). In contrast to previous works that assumed transient drop shapes are spherical, they are determined here by simulation and used to identify the natural modes of axisymmetric oscillations from resonances observed during frequency sweeps with DDSs for which the combined volume V of the two drops is less than (4/3)πR 3. Pressure and axial excitations are found to have identical responses but axial and radial excitations are shown to excite different modes. These modes are compared to those exhibited by single pendant (sessile) drop systems. Specifically, while a single pendant (sessile) drop has one additional oscillation mode compared to a free drop, a DDS is found to exhibit roughly twice as many oscillation modes as a pendant (sessile) drop. The effects of dimensionless volume V/R 3, dimensionless plate thickness d/R, and Ohnesorge number Oh =μ/√ρRσ , where σ is the surface tension of the DDS-gas interface, on the resonance frequencies are also investigated.« less

  19. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stan, Claudiu A.; Willmott, Philip R.; Stone, Howard A.

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below –100 MPamore » were reached in the drops. As a result, we model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.« less

  20. Resistance to forced airflow through layers of composting organic material.

    PubMed

    Teixeira, Denis Leocádio; de Matos, Antonio Teixeira; Melo, Evandro de Castro

    2015-02-01

    The objective of this study was to adjust equations to estimate the static pressure gradient of airflow through layers of organic residues submitted to two stages of biochemical degradation, and to evaluate the static pressure drop of airflow thought the material layer. Measurements of static pressure drop in the layers of sugarcane bagasse and coffee husks mixed with poultry litter on day 0 and after 30 days of composting were performed using a prototype with specific airflow rates ranging from 0.02 to 0.13 m(3) s(-1) m(-2). Static pressure gradient and specific airflow rate data were properly fit to the Shedd, Hukill & Ives and Ergun models, which may be used to predict the static pressure gradient of air to be blown through the organic residue layers. However, the Shedd model was that which best represented the phenomenon studied. The static pressure drop of airflow increased as a power of the material layer thickness and showed tendency for decreasing with the biochemical degradation time of the organic material. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Combining liquid inertia with pressure recovery from bubble expansion for enhanced flow boiling

    NASA Astrophysics Data System (ADS)

    Kalani, A.; Kandlikar, S. G.

    2015-11-01

    In this paper, we demonstrate using liquid inertia force in a taper gap microchannel geometry to provide a high level of heat dissipation capacity accompanied by a high heat transfer coefficient and low pressure drop during flow boiling. The high mass flux increases liquid inertia force and promotes vapor removal from the manifold, thereby increasing critical heat flux (CHF) and heat transfer coefficient. The tapered gap above the microchannels provides an increasing cross-sectional area in the flow direction. This gap allows bubbles to emerge from microchannels and expand within the gap along the flow direction. The bubble evaporation and expansion in tapered gap causes pressure recovery and reduces the total pressure drop. The pressure recovery increases with the increased evaporation rate at higher heat fluxes. Using a 6% taper and a moderately high inlet liquid flow Reynolds number of 1095, we have reached a CHF of 1.07 kW/cm2 with a heat transfer coefficient of 295 kW/m2 °C and a pressure drop of 30 kPa.

  2. Regenerator filled with a matrix of polycrystalline iron whiskers

    NASA Astrophysics Data System (ADS)

    Eder, F. X.; Appel, H.

    1982-08-01

    In thermal regenerators, parameters were optimized: convection coefficient, surface of heat accumulating matrix, matrix density and heat capacity, and frequency of cycle inversions. The variation of heat capacity with working temperature was also computed. Polycrystalline iron whiskers prove a good compromise as matrix for heat regenerators at working temperatures ranging from 300 to 80 K. They were compared with wire mesh screens and microspheres of bronze and stainless steel. For theses structures and materials, thermal conductivity, pressure drop, heat transfer and yield were calculated and related to the experimental values. As transport heat gas, helium, argon, and dry nitrogen were applied at pressures up to 20 bar. Experimental and theoretical studies result in a set of formulas for calculating pressure drop, heat capacity, and heat transfer rate for a given thermal regenerator in function of mass flow. It is proved that a whisker matrix has an efficiency that depends strongly on gas pressure and composition. Iron whiskers make a good matrix with heat capacities of kW/cu cm per K, but their relative high pressure drop may, at low pressures, be a limitation. A regenerator expansion machine is described.

  3. Langmuir Probe Measurements in an Inductively Coupled Ar/CF4 Plasmas

    NASA Technical Reports Server (NTRS)

    Rao, M. V. V. S.; Meyyappan, M.; Sharma, S. P.; Arnold, James O. (Technical Monitor)

    2000-01-01

    Technological advancement in the microelectronics industry requires an understanding of the physical and chemical processes occurring in plasmas of fluorocarbon gases, such as carbon tetrafluoride (CF4) which is commonly used as an etchant, and their mixtures to optimize various operating parameters. In this paper we report data on electron number density (ne), electron temperature'(Te), electron energy distribution function (EEDF), mean electron energy, ion number density (ni), and plasma potential (Vp) measured by using Langmuir probe in an inductively coupled 13.56 MHz radio frequency plasmas generated in 50%Ar:50%CF4 mixture in the GEC cell. The probe data were recorded at various radial positions providing radial profiles of these plasma parameters at 10-50 mTorr pressures and 200 W and 300 W of RF power. Present measurements indicate that the electron and ion number densities increase with increase in pressure and power. Whereas the plasma potential and electron temperature decrease with increase in pressure, and they weakly depend on RF power. The radial profiles exhibit that the electron and ion number densities and the plasma potential peak at the center of the plasma with an exponential fall away from it, while the electron temperature has a minimum at the center and it increases steadily towards the electrode edge. The EEDFs have a characteristic drop near the low energy end at all pressures and pressures and their shapes represent non-Maxwellian plasma and exhibit more like Druyvesteyn energy distribution.v

  4. The behavior of a liquid drop levitated and drastically flattened by an intense sound field

    NASA Technical Reports Server (NTRS)

    Lee, C. P.; Anilkumar, A. V.; Wang, Taylor G.

    1992-01-01

    The deformation and break-up are studied of a liquid drop in levitation through the radiation pressure. Using high-speed photography ripples are observed on the central membrane of the drop, atomization of the membrane by emission of satellite drops from its unstable ripples, and shattering of the drop after upward buckling like an umbrella, or after horizontal expansion like a sheet. These effects are captured on video. The ripples are theorized to be capillary waves generated by the Faraday instability excited by the sound vibration. Atomization occurs whenever the membrane becomes so thin that the vibration is sufficiently intense. The vibration leads to a destabilizing Bernoulli correction in the static pressure. Buckling occurs when an existent equilibrium is unstable to a radial (i.e., tangential) motion of the membrane because of the Bernoulli effect. Besides, the radiation stress at the rim of the drop is a suction stress which can make equilibrium impossible, leading to the horizontal expansion and the subsequent break-up.

  5. Ex-situ gas diffusion layer intrusion effect determination of polymer electrolyte membrane fuel cell flow fields

    NASA Astrophysics Data System (ADS)

    Haase, S.; Rauber, M.

    2015-09-01

    In automotive PEM fuel cell systems, one of the most important targets is to reduce the parasitic power of balance of plant components, e.g. the air supply. This can be achieved for example by decreasing air stoichiometry. However, this could lead to bad flow sharing in the fuel cell stack. Therefore the fluid distribution in the flow field has to be evaluated, understood and optimized. This work evaluates the effect of GDL intrusion on the pressure drop via ex-situ determination of GDL intrusion using CFD simulation. The intruded GDL geometries, evaluated by an optical microscope with 200 times enlargement, are transferred to pressure drop behaviors by a numerical CFD model. These results are compared to the results of the differential pressure method of mapping the pressure distribution, described in [43]. The intrusion of the GDL leads to homogeneous flow distribution up to clamping pressures of 2.5 MPa. The inhomogeneous intrusion, induced by cracked fibers that extend into the channel, dominates the flow at higher clamping pressures and leads to the exponential increase in pressure drop in the differential pressure method. For clamping pressures used in typical fuel cell applications, the results of both methods show homogeneous flow through the channels.

  6. Forecasting giant, catastrophic slope collapse: lessons from Vajont, Northern Italy

    NASA Astrophysics Data System (ADS)

    Kilburn, Christopher R. J.; Petley, David N.

    2003-08-01

    Rapid, giant landslides, or sturzstroms, are among the most powerful natural hazards on Earth. They have minimum volumes of ˜10 6-10 7 m 3 and, normally preceded by prolonged intervals of accelerating creep, are produced by catastrophic and deep-seated slope collapse (loads ˜1-10 MPa). Conventional analyses attribute rapid collapse to unusual mechanisms, such as the vaporization of ground water during sliding. Here, catastrophic collapse is related to self-accelerating rock fracture, common in crustal rocks at loads ˜1-10 MPa and readily catalysed by circulating fluids. Fracturing produces an abrupt drop in resisting stress. Measured stress drops in crustal rock account for minimum sturzstrom volumes and rapid collapse accelerations. Fracturing also provides a physical basis for quantitatively forecasting catastrophic slope failure.

  7. Plasma dynamics on current-carrying magnetic flux tubes

    NASA Technical Reports Server (NTRS)

    Swift, Daniel W.

    1992-01-01

    A 1D numerical simulation is used to investigate the evolution of a plasma in a current-carrying magnetic flux tube of variable cross section. A large potential difference, parallel to the magnetic field, is applied across the domain. The result is that density minimum tends to deepen, primarily in the cathode end, and the entire potential drop becomes concentrated across the region of density minimum. The evolution of the simulation shows some sensitivity to particle boundary conditions, but the simulations inevitably evolve into a final state with a nearly stationary double layer near the cathode end. The simulation results are at sufficient variance with observations that it appears unlikely that auroral electrons can be explained by a simple process of acceleration through a field-aligned potential drop.

  8. Snake constriction rapidly induces circulatory arrest in rats.

    PubMed

    Boback, Scott M; McCann, Katelyn J; Wood, Kevin A; McNeal, Patrick M; Blankenship, Emmett L; Zwemer, Charles F

    2015-07-01

    As legless predators, snakes are unique in their ability to immobilize and kill their prey through the process of constriction, and yet how this pressure incapacitates and ultimately kills the prey remains unknown. In this study, we examined the cardiovascular function of anesthetized rats before, during and after being constricted by boas (Boa constrictor) to examine the effect of constriction on the prey's circulatory function. The results demonstrate that within 6 s of being constricted, peripheral arterial blood pressure (PBP) at the femoral artery dropped to 1/2 of baseline values while central venous pressure (CVP) increased 6-fold from baseline during the same time. Electrocardiographic recordings from the anesthetized rat's heart revealed profound bradycardia as heart rate (fH) dropped to nearly half of baseline within 60 s of being constricted, and QRS duration nearly doubled over the same time period. By the end of constriction (mean 6.5±1 min), rat PBP dropped 2.9-fold, fH dropped 3.9-fold, systemic perfusion pressure (SPP=PBP-CVP) dropped 5.7-fold, and 91% of rats (10 of 11) had evidence of cardiac electrical dysfunction. Blood drawn immediately after constriction revealed that, relative to baseline, rats were hyperkalemic (serum potassium levels nearly doubled) and acidotic (blood pH dropped from 7.4 to 7.0). These results are the first to document the physiological response of prey to constriction and support the hypothesis that snake constriction induces rapid prey death due to circulatory arrest. © 2015. Published by The Company of Biologists Ltd.

  9. [Filtering facepieces: effect of oily aerosol load on penetration through the filtering material].

    PubMed

    Plebani, Carmela; Listrani, S; Di Luigi, M

    2010-01-01

    Electrostatic filters are widely used in applications requiring high filtration efficiency and low pressure drop. However various studies showed that the penetration through electrostatic filters increases during exposure to an aerosol flow. This study investigates the effects of prolonged exposure to an oily aerosol on the penetration through filtering facepieces available on the market. Some samples of FFP1, FFP2 and FFP3 filtering facepieces were exposed for 8 hours consecutively to a paraffin oil polydisperse aerosol. At the end of the exposure about 830 mg of paraffin oil were deposited in the facepiece. All the examined facepieces showed penetration values that increased with paraffin oil load while pressure drop values were substantially the same before and after exposure. The measured maximum penetration values did not exceed the maximum penetration values allowed by the European technical standards, except in one case. According to the literature, 830 mg of oil load in a facepiece is not feasible in workplaces over an eight- hour shift. However, the trend of the penetration versus exposure mass suggests that if the load increases, the penetration may exceed the maximum allowed values. For comparison a mechanical filter was also studied. This showed an initial pressure drop higher than FFP2 filtering facepieces characterized by comparable penetration values. During exposure the pressure drop virtually doubled while penetration did not change. The increase in penetration with no increase in pressure drop in the analyzed facepieces indicates that it is necessary to comply with the information supplied by the manufacturer that restricts their use to a single shift.

  10. An experimental study on the design, performance and suitability of evaporative cooling system using different indigenous materials

    NASA Astrophysics Data System (ADS)

    Alam, Md. Ferdous; Sazidy, Ahmad Sharif; Kabir, Asif; Mridha, Gowtam; Litu, Nazmul Alam; Rahman, Md. Ashiqur

    2017-06-01

    The present study aimed to evaluate the feasibility of coconut coir pads, jute fiber pads and sackcloth pads as alternative pad materials. Experimental measurements were conducted and the experimental data were quantitative. The experimental work mainly focused on the effects of different types and thicknesses of evaporative cooling pads by using forced draft fan while changing the environmental conditions. Experiments are conducted in a specifically constructed test chamber having dimensions of 12'X8'X8', using a number of cooling pads (36"X26") with a variable thickness parameters of the evaporative cooling pads i.e., 50, 75 and 100 mm. Moreover, the experimental work involved the measurement of environmental parameters such as temperature, relative humidity, air velocity, water mass flow rate and pressure drops at different times during the day. Experiments were conducted at three different water mass flow rates (0.25 kgs-1, 0.40 kgs-1 & 0.55 kgs-1) and three different air velocities (3.6 ms-1, 4.6 ms-1& 5.6 ms-1). There was a significant difference between evaporative cooling pad types and cooling efficiency. The coconut coir pads yielded maximum cooling efficiency of 85%, whereas other pads yielded the following maximum cooling efficiency: jute fiber pads 78% and sackcloth 69% for higher air velocity and minimum mass flow rate. It is found that the maximum reduction in temperature between cooling pad inlet and outlet is 4°C with a considerable increase in humidity. With the increase of pad thickness there was an increment of cooling efficiency. The results obtained for environmental factors, indicated that there was a significant difference between environmental factors and cooling efficiency. In terms of the effect of air velocity on saturation efficiency and pressure drop, higher air velocity decreases saturation efficiency and increases pressure drop across the wetted pad for maximum flow rate. Convective heat transfer co-efficient has an almost linear relationship with air Velocity. Water consumption or evaporation rate increases with the increase in air velocity. Finally, the present study indicated that the coconut coir pads perform better than the other evaporative cooling pads and have higher potential as wetted-pad material. The outcomes of this study can provide an effective and low-cost solution in the form of evaporative cooling system, especially in an agricultural country like Bangladesh.

  11. 40 CFR Table 3 to Subpart Jjjjjj... - Operating Limits for Boilers With Emission Limits

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... system alarm does not sound more than 5 percent of the operating time during each 6-month period. 2... the pressure drop at or above the lowest 1-hour average pressure drop across the wet scrubber and the... recent performance stack test. 8. Continuous Oxygen Monitor Maintain the oxygen level at or above the...

  12. 40 CFR 63.9917 - How do I demonstrate initial compliance with the emission limitations and work practice standards...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... subpart; and (2) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you have established appropriate site-specific operating limits and have a record of the pressure drop and scrubber water flow rate measured during the performance test in...

  13. 40 CFR 63.9923 - How do I demonstrate continuous compliance with the emission limitations and work practice...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to this subpart. (b) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must demonstrate continuous compliance according to the... according to § 63.9921(b); and (2) Maintaining the hourly average pressure drop and scrubber water flow rate...

  14. 40 CFR 63.9917 - How do I demonstrate initial compliance with the emission limitations and work practice standards...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... subpart; and (2) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you have established appropriate site-specific operating limits and have a record of the pressure drop and scrubber water flow rate measured during the performance test in...

  15. 40 CFR 63.9923 - How do I demonstrate continuous compliance with the emission limitations and work practice...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... to this subpart. (b) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must demonstrate continuous compliance according to the... according to § 63.9921(b); and (2) Maintaining the hourly average pressure drop and scrubber water flow rate...

  16. 40 CFR 63.9917 - How do I demonstrate initial compliance with the emission limitations and work practice standards...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... subpart; and (2) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you have established appropriate site-specific operating limits and have a record of the pressure drop and scrubber water flow rate measured during the performance test in...

  17. 40 CFR 63.9923 - How do I demonstrate continuous compliance with the emission limitations and work practice...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... to this subpart. (b) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must demonstrate continuous compliance according to the... according to § 63.9921(b); and (2) Maintaining the hourly average pressure drop and scrubber water flow rate...

  18. 40 CFR 63.9917 - How do I demonstrate initial compliance with the emission limitations and work practice standards...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... subpart; and (2) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you have established appropriate site-specific operating limits and have a record of the pressure drop and scrubber water flow rate measured during the performance test in...

  19. 40 CFR 63.9923 - How do I demonstrate continuous compliance with the emission limitations and work practice...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... to this subpart. (b) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must demonstrate continuous compliance according to the... according to § 63.9921(b); and (2) Maintaining the hourly average pressure drop and scrubber water flow rate...

  20. 40 CFR 63.9917 - How do I demonstrate initial compliance with the emission limitations and work practice standards...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... subpart; and (2) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you have established appropriate site-specific operating limits and have a record of the pressure drop and scrubber water flow rate measured during the performance test in...

  1. 40 CFR 63.9923 - How do I demonstrate continuous compliance with the emission limitations and work practice...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... to this subpart. (b) For each wet scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must demonstrate continuous compliance according to the... according to § 63.9921(b); and (2) Maintaining the hourly average pressure drop and scrubber water flow rate...

  2. Antimisting kerosene: Low temperature degradation and blending

    NASA Technical Reports Server (NTRS)

    Yavrouian, A.; Parikh, P.; Sarohia, V.

    1988-01-01

    The inline filtration characteristics of freshly blended and degraded antimisting fuels (AMK) at low temperature are examined. A needle valve degrader was modified to include partial recirculation of degraded fuel and heat addition in the bypass loop. A pressure drop across the needle valve of up to 4,000 psi was used. The pressure drop across a 325 mesh filter screen placed inline with the degrader and directly downstream of the needle valve was measured as a function of time for different values of pressure drop across the needle valve. A volume flux of 1 gpm/sq in was employed based on the frontal area of the screen. It was found that, at ambient temperatures, freshly blended AMK fuel could be degraded using a single pass degradation at 4,000 psi pressure drop across the needle valve to give acceptable filterability performance. At fuel temperatures below -20 C, degradation becomes increasingly difficult and a single pass technique results in unacceptable filtration performance. Recirculation of a fraction of the degraded fuel and heat addition in the bypass loop improved low temperature degradation performance. The problem is addressed of blending the AMK additive with Jet A at various base fuel temperatures.

  3. Evaluation of cooling performance of impinging jet array over various dimpled surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Sun-Min; Kim, Kwang-Yong

    2016-04-01

    Various configurations of an impinging jet-dimple array cooling system were evaluated in terms of their heat transfer and pressure drop performances. The steady incompressible laminar flow and heat transfer in the cooling system were analyzed using three-dimensional Navier-Stokes equations. The obtained numerical results were validated by a comparison with experimental data for the local Nusselt number distribution. The area-averaged Nusselt number on the projected area and the pressure drop through the system were selected as the performance parameters. Among the four tested configurations—inline concave, staggered concave, inline convex, and staggered convex—the staggered convex impinging jet-dimple array showed the best heat transfer performance whereas the staggered-concave configuration showed the lowest pressure drop. A parametric study with two geometric variables, i.e., the height of dimple and the diameter of dimple, was also conducted for the staggered-convex impinging jet-dimple array. As a result, the best heat transfer and pressure drop performances were achieved when the ratio of the height of dimple to the diameter of jet was 0.8. And, the increase in the ratio of the diameter of dimple to the diameter of jet yielded monotonous increase in the heat transfer performance.

  4. Characterisation and optimisation of flexible transfer lines for liquid helium. Part II: Thermohydraulic modelling

    NASA Astrophysics Data System (ADS)

    Dittmar, N.; Haberstroh, Ch.; Hesse, U.; Krzyzowski, M.

    2016-10-01

    In part one of this publication experimental results for a single-channel transfer line used at liquid helium (LHe) decant stations are presented. The transfer of LHe into mobile dewars is an unavoidable process since the places of storage and usage are generally located apart from each other. The experimental results have shown that reasonable amounts of LHe evaporate due to heat leak and pressure drop. Thus, generated helium cold gas has to be collected and reliquefied, demanding a huge amount of electrical energy. Although this transfer process is common in cryogenic laboratories, no existing code could be found to model it. Therefore, a thermohydraulic model has been developed to model the LHe flow at operating conditions using published heat transfer and pressure drop correlations. This paper covers the basic equations used to calculate heat transfer and pressure drop, as well as the validation of the thermohydraulic code, and its application within the optimisation process. The final transfer line design features reduced heat leak and pressure drop values based on a combined measurement and modelling campaign in the range of 0.112 < pin < 0.148 MPa, 190 < G < 450 kg/(m2 s), and 0.04 < xout < 0.12.

  5. The transition from frictional sliding to shear melting in laboratory experiments and the implications for scale dependent earthquake source properties

    NASA Astrophysics Data System (ADS)

    Beeler, N. M.; Lockner, D. A.; Kilgore, B. D.; Moore, D. E.

    2011-12-01

    Localized slip during earthquakes, e.g., at 1 m/s for a few seconds, should produce enough thermal energy to melt rock or pressurize pore fluid and drastically reduce fault strength (Sibson, Nature Phys. Sci., 1973. Sibson, Geophys. J. R. Astr. Soc., 1975). Expected changes in earthquake source properties for events with large enough temperature change to induce melting or fluid pressurization include an increase in stress drop, a possible increase in low frequency content of the radiated energy and an increase in the ratio of radiated energy to seismic moment. Such changes with increasing moment, while expected, are not observed seismologically and the role of thermal weakening during large earthquakes remains unknown. To investigate the effect of the onset of thermal weakening on earthquake source properties such as stress drop, slip velocity, weakening distance, and apparent stress, we have conducted stick-slip experiments at confining pressures between 50 and 400 MPa on initially bare rock surfaces of Westerly granite (Lockner et al., Eos Trans. Am. Geophys. Un. T23A-2245, 2010). These conditions span a transition from frictional sliding, producing dry comminuted fault gouge and fractional stress drops at lower confining pressure, to shear induced melting with complete stress drop at the highest pressures. The confining pressure, axial stress and displacement, are measured as in standard faulting tests. Temperature is monitored with a thermocouple ~2.5 mm from the fault. Rapid motions of the fault are inferred from independent recordings of the acceleration and velocity of the loading piston using an accelerometer and a laser Doppler vibrometer. Slip velocity, and event duration increase with stress drop. Stress drops vary from less than 10 to greater than 400 MPa. Durations are between 0.1 and 0.5 ms and average sliding velocities range from <1 to > 10 m/s. Total stress drop is associated with slip and shear stress sufficient to increase the entire shear zone temperature to the melting point of feldspar, but melt is also found in samples subjected to smaller stress drops, suggesting heating to somewhat lower temperature. Stress and slip constrain the total energy; the temperature measurements constrain the energy associated with frictional heating and the heat of fusion, while the velocity measurements allow an estimate of the radiated energy. Using these constraints and models of shear-induced melting we examine changes in event source properties across the transition to shear melting.

  6. The possible equilibrium shapes of static pendant drops

    NASA Astrophysics Data System (ADS)

    Sumesh, P. T.; Govindarajan, Rama

    2010-10-01

    Analytical and numerical studies are carried out on the shapes of two-dimensional and axisymmetric pendant drops hanging under gravity from a solid surface. Drop shapes with both pinned and equilibrium contact angles are obtained naturally from a single boundary condition in the analytical energy optimization procedure. The numerical procedure also yields optimum energy shapes, satisfying Young's equation without the explicit imposition of a boundary condition at the plate. It is shown analytically that a static pendant two-dimensional drop can never be longer than 3.42 times the capillary length. A related finding is that a range of existing solutions for long two-dimensional drops correspond to unphysical drop shapes. Therefore, two-dimensional drops of small volume display only one static solution. In contrast, it is known that axisymmetric drops can display multiple solutions for a given volume. We demonstrate numerically that there is no limit to the height of multiple-lobed Kelvin drops, but the total volume is finite, with the volume of successive lobes forming a convergent series. The stability of such drops is in question, though. Drops of small volume can attain large heights. A bifurcation is found within the one-parameter space of Laplacian shapes, with a range of longer drops displaying a minimum in energy in the investigated space. Axisymmetric Kelvin drops exhibit an infinite number of bifurcations.

  7. A comparison of preservative-free diclofenac and preserved diclofenac eye drops after cataract surgery in patients with diabetic retinopathy.

    PubMed

    Yasuda, Kanako; Miyazawa, Akiko; Shimura, Masahiko

    2012-06-01

    The aim of this study was to compare the anti-inflammatory efficacy of preservative-free and preserved 0.1% diclofenac eye drops for the management of postoperative inflammation after cataract surgery in patients with nonproliferative diabetic retinopathy and in normal controls. Forty-two diabetic patients and 50 normal control patients who underwent small-incision phacoemulsification cataract surgery bilaterally received topical preservative-free diclofenac in 1 eye and preserved diclofenac in the other eye. The corrected distance visual acuity (CDVA) as determined by a logarithm of the minimum angle of resolution (logMAR) chart, intraocular pressure (IOP), foveal thickness (FT) using optical coherence tomography (OCT), and the anterior chamber flare (ACF) score measured with a laser flare cell meter were monitored for 12 weeks after surgery. In the eyes with diabetic retinopathy, there were no significant differences in CDVA, IOP, FT, and ACF score between the right and left eyes at the initial exam. After cataract surgery, changes in CDVA, IOP, and FT were not influenced by the preservative in the diclofenac eye drops. In contrast, the ACF score in the eyes treated with preserved diclofenac showed slower recovery from postoperative inflammation than the eyes treated with preservative-free diclofenac. In the normal control eyes, similar but milder changes were observed in each of the clinical parameters. Because preservative suppressed the anti-inflammatory efficacy of topical diclofenac after cataract surgery, preservative-free diclofenac may have an improved safety profile during postoperative treatment, especially in patients with diabetic retinopathy.

  8. Low blood pressure

    MedlinePlus

    Hypotension; Blood pressure - low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH ... Blood pressure varies from one person to another. A drop as little as 20 mmHg, can cause ...

  9. Usability of prostaglandin monotherapy eye droppers.

    PubMed

    Drew, Tom; Wolffsohn, James S

    2015-09-01

    To determine the force needed to extract a drop from a range of current prostaglandin monotherapy eye droppers and how this related to the comfortable and maximum pressure subjects could exert. The comfortable and maximum pressure subjects could apply to an eye dropper constructed around a set of cantilevered pressure sensors and mounted above their eye was assessed in 102 subjects (mean 51.2±18.7 years), repeated three times. A load cell amplifier, mounted on a stepper motor controlled linear slide, was constructed and calibrated to test the force required to extract the first three drops from 13 multidose or unidose latanoprost medication eye droppers. The pressure that could be exerted on a dropper comfortably (25.9±17.7 Newtons, range 1.2-87.4) could be exceeded with effort (to 64.8±27.1 Newtons, range 19.9-157.8; F=19.045, p<0.001), and did not differ between repeats (F=0.609, p=0.545). Comfortable and maximum pressures exerted were correlated (r=0.618, p<0.001), neither were influenced strongly by age (r=0.138, p=0.168; r=-0.118, p=0237, respectively), but were lower in women than in men (F=12.757, p=0.001). The force required to expel a drop differed between dropper designs (F=22.528, p<0.001), ranging from 6.4 Newtons to 23.4 Newtons. The force needed to exert successive drops increased (F=36.373, p<0.001) and storing droppers in the fridge further increased the force required (F=7.987, p=0.009). Prostaglandin monotherapy droppers for glaucoma treatment vary in their resistance to extract a drop and with some a drop could not be comfortably achieved by half the population, which may affect compliance and efficacy. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  10. Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section

    NASA Astrophysics Data System (ADS)

    Elazhary, Amr Mohamed; Soliman, Hassan M.

    2012-10-01

    An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 ≤ JG ≤ 10 m/s and 0.02 ≤ JL ≤ 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.

  11. The dynamics of financial stability in complex networks

    NASA Astrophysics Data System (ADS)

    da Cruz, J. P.; Lind, P. G.

    2012-08-01

    We address the problem of banking system resilience by applying off-equilibrium statistical physics to a system of particles, representing the economic agents, modelled according to the theoretical foundation of the current banking regulation, the so called Merton-Vasicek model. Economic agents are attracted to each other to exchange `economic energy', forming a network of trades. When the capital level of one economic agent drops below a minimum, the economic agent becomes insolvent. The insolvency of one single economic agent affects the economic energy of all its neighbours which thus become susceptible to insolvency, being able to trigger a chain of insolvencies (avalanche). We show that the distribution of avalanche sizes follows a power-law whose exponent depends on the minimum capital level. Furthermore, we present evidence that under an increase in the minimum capital level, large crashes will be avoided only if one assumes that agents will accept a drop in business levels, while keeping their trading attitudes and policies unchanged. The alternative assumption, that agents will try to restore their business levels, may lead to the unexpected consequence that large crises occur with higher probability.

  12. Concentrated energy addition for active drag reduction in hypersonic flow regime

    NASA Astrophysics Data System (ADS)

    Ashwin Ganesh, M.; John, Bibin

    2018-01-01

    Numerical optimization of hypersonic drag reduction technique based on concentrated energy addition is presented in this study. A reduction in wave drag is realized through concentrated energy addition in the hypersonic flowfield upstream of the blunt body. For the exhaustive optimization presented in this study, an in-house high precision inviscid flow solver has been developed. Studies focused on the identification of "optimum energy addition location" have revealed the existence of multiple minimum drag points. The wave drag coefficient is observed to drop from 0.85 to 0.45 when 50 Watts of energy is added to an energy bubble of 1 mm radius located at 74.7 mm upstream of the stagnation point. A direct proportionality has been identified between energy bubble size and wave drag coefficient. Dependence of drag coefficient on the upstream added energy magnitude is also revealed. Of the observed multiple minimum drag points, the energy deposition point (EDP) that offers minimum wave drag just after a sharp drop in drag is proposed as the most optimum energy addition location.

  13. 40 CFR 63.7825 - How do I demonstrate initial compliance with the emission limitations that apply to me?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... accordance with § 63.7824(a)(1); and (3) For each venturi scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.7790(b)(2), you have established appropriate site-specific operating limits and have a record of the pressure drop and scrubber water flow rate measured...

  14. Prediction of pressure drop in fluid tuned mounts using analytical and computational techniques

    NASA Technical Reports Server (NTRS)

    Lasher, William C.; Khalilollahi, Amir; Mischler, John; Uhric, Tom

    1993-01-01

    A simplified model for predicting pressure drop in fluid tuned isolator mounts was developed. The model is based on an exact solution to the Navier-Stokes equations and was made more general through the use of empirical coefficients. The values of these coefficients were determined by numerical simulation of the flow using the commercial computational fluid dynamics (CFD) package FIDAP.

  15. 40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

  16. 40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

  17. 40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

  18. 40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

  19. 40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

  20. 40 CFR 63.9916 - What test methods and other procedures must I use to establish and demonstrate initial compliance...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... compliance with the operating limits? For a wet scrubber subject to operating limits for pressure drop and scrubber water flow rate in § 63.9890(b), you must establish site-specific operating limits according to... monitoring system (CPMS) required in § 63.9920, measure and record the pressure drop and scrubber water flow...

  1. 40 CFR 63.7825 - How do I demonstrate initial compliance with the emission limitations that apply to me?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... accordance with § 63.7824(a)(1); and (3) For each venturi scrubber subject to the operating limits for pressure drop and scrubber water flow rate in § 63.7790(b)(2), you have established appropriate site-specific operating limits and have a record of the pressure drop and scrubber water flow rate measured...

  2. 40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

  3. 40 CFR Table 2 to Subpart Zzzzz of... - Procedures for Establishing Operating Limits for New Affected Sources Classified as Large Foundries

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... using the procedures in the following table: For . . . You must . . . 1. Each wet scrubber subject to the operating limits in § 63.10895(d)(1) for pressure drop and scrubber water flow rate. Using the CPMS required in § 63.10897(b), measure and record the pressure drop and scrubber water flow rate in...

  4. Fixed Packed Bed Reactors in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro; McCready, Mark J.

    2004-01-01

    We present experimental data on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed columns in microgravity. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under microgravity conditions compared to 1-g and the widely used Talmor map in 1-g is not applicable for predicting the transition boundaries. A new transition criterion between bubble and pulse flow in microgravity is proposed and tested using the data. Since there is no static head in microgravity, the pressure drop measured is the true frictional pressure drop. The pressure drop data, which has much smaller scatter than most reported 1-g data clearly shows that capillary effects can enhance the pressure drop (especially in the bubble flow regime) as much as 200% compared to that predicted by the single phase Ergun equation. The pressure drop data are correlated in terms of a two-phase friction factor and its dependence on the gas and liquid Reynolds numbers and the Suratman number. The influence of gravity on the pulse amplitude and frequency is also discussed and compared to that under normal gravity conditions. Experimental work is planned to determine the gas-liquid and liquid-solid mass transfer coefficients. Because of enhanced interfacial effects, we expect the gas-liquid transfer coefficients kLa and kGa (where a is the gas-liquid interfacial area) to be higher in microgravity than in normal gravity at the same flow conditions. This will be verified by gas absorption experiments, with and without reaction in the liquid phase, using oxygen, carbon dioxide, water and dilute aqueous amine solutions. The liquid-solid mass transfer coefficient will also be determined in the bubble as well as the pulse flow regimes using solid benzoic acid particles in the packing and measuring their rate of dissolution. The mass transfer coefficients in microgravity will be compared to those in normal gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.

  5. Fixed Packed Bed Reactors in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro; McCready, Mark J.

    2004-01-01

    We present experimental data on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed columns in microgravity. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under microgravity conditions compared to 1-g and the widely used Talmor map in 1-g is not applicable for predicting the transition boundaries. A new transition criterion between bubble and pulse flow in microgravity is proposed and tested using the data. Since there is no static head in microgravity, the pressure drop measured is the true frictional pressure drop. The pressure drop data, which has much smaller scatter than most reported 1-g data clearly shows that capillary effects can enhance the pressure drop (especially in the bubble flow regime) as much as 200% compared to that predicted by the single phase Ergun equation. The pressure drop data are correlated in terms of a two-phase friction factor and its dependence on the gas and liquid Reynolds numbers and the Suratman number. The influence of gravity on the pulse amplitude and frequency is also discussed and compared to that under normal gravity conditions. Experimental work is planned to determine the gas-liquid mass transfer coefficients. Because of enhanced interfacial effects, we expect the gas-liquid transfer coefficients k(L)a and k(G)a (where a is the gas-liquid interfacial area) to be higher in microgravity than in normal gravity at the same flow conditions. This will be verified by gas absorption experiments, with and without reaction in the liquid phase, using oxygen, carbon dioxide, water and dilute aqueous amine solutions. The liquid-solid mass transfer coefficient will also be determined in the bubble as well as the pulse flow regimes using solid benzoic acid particles in the packing and measuring their rate of dissolution. The mass transfer coefficients in microgravity will be compared to those in normal gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.

  6. Source Mechanism of Vulcanian Degassing at Popocatépetl Volcano, Mexico, Determined From Moment-Tensor Inversion of Very-long-period Seismic Waveforms

    NASA Astrophysics Data System (ADS)

    Chouet, B.; Dawson, P.; Arciniega, A.

    2004-12-01

    The source mechanism of very-long-period (VLP) signals accompanying degassing exhalations at Popocatépetl is analyzed in the 15-70~s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of two events (04/23/00, 05/23/00) representative of mild Vulcanian eruptions are well reproduced by our inversion, which takes into account volcano topography. The source centroid is positioned 1500~m below the western perimeter of the summit crater, and the modeled source is composed of a shallow-dipping crack (sill with easterly dip of 10° ) intersecting a steeply-dipping crack (northeast striking dike with northwest dip of 83° ), whose surface trace bisects the vent. Both cracks undergo a similar sequence of inflation, deflation, and reinflation --- reflecting a cycle of pressurization, depressurization, and repressurization within a time interval of 3-5~min. The largest moment release occurs in the sill, showing a maximum volume change of 500-1000\\:m3, pressure drop of 3-5~MPa, and amplitude of recovered pressure equal to 1.2 times the amplitude of the pressure drop. In contrast, the maximum volume change in the dike is 200-300\\:m3, with a corresponding pressure drop of 1-2~MPa and pressure recovery equal to the pressure drop. Accompanying these volumetric sources is a single force with magnitude of 5 × 108~N, consistent with melt advection in response to the pressure transients. The source-time history of the three components of this force confirms that significant mass movement starts in the sill and triggers a mass movement response in the dike within ˜ 5~s. Such source behavior is consistent with the opening of an escape pathway for accumulated gases from slow pressurization of the sill driven by magma crystallization. The opening of a pathway for pent-up gases in the sill and rapid evacuation of this separated gas phase induces the pressure drop. Pressure recovery in the magma filling the sill is driven by diffusion of gases from the resulting supersaturated melt into bubbles. Assuming a penny-shaped crack at ambient pressure of 40~MPa, the observed pressure and volume variations can be modeled with the following attributes: crack radius, (100~m), crack aperture, (5~m), bubble number density, (1010 - 1012\\:m-3), initial bubble radius, (10-6\\:m), final bubble radius, ( ˜ 10-5\\:m), and net decrease of gas concentration in the melt, (0.01~wt%).

  7. Source mechanism of Vulcanian degassing at Popocatépetl Volcano, Mexico, determined from waveform inversions of very long period signals

    NASA Astrophysics Data System (ADS)

    Chouet, Bernard; Dawson, Phillip; Arciniega-Ceballos, Alejandra

    2005-07-01

    The source mechanism of very long period (VLP) signals accompanying volcanic degassing bursts at Popocatépetl is analyzed in the 15-70 s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of two eruptions (23 April and 23 May 2000) representative of mild Vulcanian activity are well reproduced by our inversion, which takes into account volcano topography. The source centroid is positioned 1500 m below the western perimeter of the summit crater, and the modeled source is composed of a shallow dipping crack (sill with easterly dip of 10°) intersecting a steeply dipping crack (northeast striking dike dipping 83° northwest), whose surface extension bisects the vent. Both cracks undergo a similar sequence of inflation, deflation, and reinflation, reflecting a cycle of pressurization, depressurization, and repressurization within a time interval of 3-5 min. The largest moment release occurs in the sill, showing a maximum volume change of 500-1000 m3, pressure drop of 3-5 MPa, and amplitude of recovered pressure equal to 1.2 times the amplitude of the pressure drop. In contrast, the maximum volume change in the dike is less (200-300 m3), with a corresponding pressure drop of 1-2 MPa and pressure recovery equal to the pressure drop. Accompanying these volumetric sources are single-force components with magnitudes of 108 N, consistent with melt advection in response to pressure transients. The source time histories of the volumetric components of the source indicate that significant mass movement starts within the sill and triggers a mass movement response in the dike within a few seconds. Such source behavior is consistent with the opening of a pathway for escape of pent-up gases from slow pressurization of the sill driven by magma crystallization. The opening of this pathway and associated rapid evacuation of volcanic gases induces the pressure drop. Pressure recovery in the magma filling the sill is driven by diffusion of gases from the resulting supersaturated melt into bubbles. Assuming a penny-shaped crack at ambient pressure of 40 MPa, the observed pressure and volume variations can be modeled with the following attributes: crack radius (100 m), crack aperture (5 m), bubble number density (1010-1012 m-3), initial bubble radius (10-6 m), final bubble radius (˜10-5 m), and net decrease of gas concentration in the melt (0.01 wt %).

  8. Source mechanism of Vulcanian degassing at Popocatépetl Volcano, Mexico, determined from waveform inversions of very long period signals

    USGS Publications Warehouse

    Chouet, Bernard A.; Dawson, Phillip B.; Arciniega-Ceballos, Alejandra

    2005-01-01

    The source mechanism of very long period (VLP) signals accompanying volcanic degassing bursts at Popocatépetl is analyzed in the 15–70 s band by minimizing the residual error between data and synthetics calculated for a point source embedded in a homogeneous medium. The waveforms of two eruptions (23 April and 23 May 2000) representative of mild Vulcanian activity are well reproduced by our inversion, which takes into account volcano topography. The source centroid is positioned 1500 m below the western perimeter of the summit crater, and the modeled source is composed of a shallow dipping crack (sill with easterly dip of 10°) intersecting a steeply dipping crack (northeast striking dike dipping 83° northwest), whose surface extension bisects the vent. Both cracks undergo a similar sequence of inflation, deflation, and reinflation, reflecting a cycle of pressurization, depressurization, and repressurization within a time interval of 3–5 min. The largest moment release occurs in the sill, showing a maximum volume change of 500–1000 m3, pressure drop of 3–5 MPa, and amplitude of recovered pressure equal to 1.2 times the amplitude of the pressure drop. In contrast, the maximum volume change in the dike is less (200–300 m3), with a corresponding pressure drop of 1–2 MPa and pressure recovery equal to the pressure drop. Accompanying these volumetric sources are single-force components with magnitudes of 108 N, consistent with melt advection in response to pressure transients. The source time histories of the volumetric components of the source indicate that significant mass movement starts within the sill and triggers a mass movement response in the dike within a few seconds. Such source behavior is consistent with the opening of a pathway for escape of pent-up gases from slow pressurization of the sill driven by magma crystallization. The opening of this pathway and associated rapid evacuation of volcanic gases induces the pressure drop. Pressure recovery in the magma filling the sill is driven by diffusion of gases from the resulting supersaturated melt into bubbles. Assuming a penny-shaped crack at ambient pressure of 40 MPa, the observed pressure and volume variations can be modeled with the following attributes: crack radius (100 m), crack aperture (5 m), bubble number density (1010–1012 m−3), initial bubble radius (10−6 m), final bubble radius (∼10−5 m), and net decrease of gas concentration in the melt (0.01 wt %).

  9. Analysis of supercritical CO{sub 2} cycle control strategies and dynamic response for Generation IV Reactors.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Moisseytsev, A.; Sienicki, J. J.

    2011-04-12

    The analysis of specific control strategies and dynamic behavior of the supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle has been extended to the two reactor types selected for continued development under the Generation IV Nuclear Energy Systems Initiative; namely, the Very High Temperature Reactor (VHTR) and the Sodium-Cooled Fast Reactor (SFR). Direct application of the standard S-CO{sub 2} recompression cycle to the VHTR was found to be challenging because of the mismatch in the temperature drop of the He gaseous reactor coolant through the He-to-CO{sub 2} reactor heat exchanger (RHX) versus the temperature rise of the CO{sub 2} through themore » RHX. The reference VHTR features a large temperature drop of 450 C between the assumed core outlet and inlet temperatures of 850 and 400 C, respectively. This large temperature difference is an essential feature of the VHTR enabling a lower He flow rate reducing the required core velocities and pressure drop. In contrast, the standard recompression S-CO{sub 2} cycle wants to operate with a temperature rise through the RHX of about 150 C reflecting the temperature drop as the CO{sub 2} expands from 20 MPa to 7.4 MPa in the turbine and the fact that the cycle is highly recuperated such that the CO{sub 2} entering the RHX is effectively preheated. Because of this mismatch, direct application of the standard recompression cycle results in a relatively poor cycle efficiency of 44.9%. However, two approaches have been identified by which the S-CO{sub 2} cycle can be successfully adapted to the VHTR and the benefits of the S-CO{sub 2} cycle, especially a significant gain in cycle efficiency, can be realized. The first approach involves the use of three separate cascaded S-CO{sub 2} cycles. Each S-CO{sub 2} cycle is coupled to the VHTR through its own He-to-CO{sub 2} RHX in which the He temperature is reduced by 150 C. The three respective cycles have efficiencies of 54, 50, and 44%, respectively, resulting in a net cycle efficiency of 49.3 %. The other approach involves reducing the minimum cycle pressure significantly below the critical pressure such that the temperature drop in the turbine is increased while the minimum cycle temperature is maintained above the critical temperature to prevent the formation of a liquid phase. The latter approach also involves the addition of a precooler and a third compressor before the main compressor to retain the benefits of compression near the critical point with the main compressor. For a minimum cycle pressure of 1 MPa, a cycle efficiency of 49.5% is achieved. Either approach opens up the door to applying the SCO{sub 2} cycle to the VHTR. In contrast, the SFR system typically has a core outlet-inlet temperature difference of about 150 C such that the standard recompression cycle is ideally suited for direct application to the SFR. The ANL Plant Dynamics Code has been modified for application to the VHTR and SFR when the reactor side dynamic behavior is calculated with another system level computer code such as SAS4A/SYSSYS-1 in the SFR case. The key modification involves modeling heat exchange in the RHX, accepting time dependent tabular input from the reactor code, and generating time dependent tabular input to the reactor code such that both the reactor and S-CO{sub 2} cycle sides can be calculated in a convergent iterative scheme. This approach retains the modeling benefits provided by the detailed reactor system level code and can be applied to any reactor system type incorporating a S-CO{sub 2} cycle. This approach was applied to the particular calculation of a scram scenario for a SFR in which the main and intermediate sodium pumps are not tripped and the generator is not disconnected from the electrical grid in order to enhance heat removal from the reactor system thereby enhancing the cooldown rate of the Na-to-CO{sub 2} RHX. The reactor side is calculated with SAS4A/SASSYS-1 while the S-CO{sub 2} cycle is calculated with the Plant Dynamics Code with a number of iterations over a timescale of 500 seconds. It is found that the RHX undergoes a maximum cooldown rate of {approx} -0.3 C/s. The Plant Dynamics Code was also modified to decrease its running time by replacing the compressible flow form of the momentum equation with an incompressible flow equation for use inside of the cooler or recuperators where the CO{sub 2} has a compressibility similar to that of a liquid. Appendices provide a quasi-static control strategy for a SFR as well as the self-adaptive linear function fitting algorithm developed to produce the tabular data for input to the reactor code and Plant Dynamics Code from the detailed output of the other code.« less

  10. A study of power cycles using supercritical carbon dioxide as the working fluid

    NASA Astrophysics Data System (ADS)

    Schroder, Andrew Urban

    A real fluid heat engine power cycle analysis code has been developed for analyzing the zero dimensional performance of a general recuperated, recompression, precompression supercritical carbon dioxide power cycle with reheat and a unique shaft configuration. With the proposed shaft configuration, several smaller compressor-turbine pairs could be placed inside of a pressure vessel in order to avoid high speed, high pressure rotating seals. The small compressor-turbine pairs would share some resemblance with a turbocharger assembly. Variation in fluid properties within the heat exchangers is taken into account by discretizing zero dimensional heat exchangers. The cycle analysis code allows for multiple reheat stages, as well as an option for the main compressor to be powered by a dedicated turbine or an electrical motor. Variation in performance with respect to design heat exchanger pressure drops and minimum temperature differences, precompressor pressure ratio, main compressor pressure ratio, recompression mass fraction, main compressor inlet pressure, and low temperature recuperator mass fraction have been explored throughout a range of each design parameter. Turbomachinery isentropic efficiencies are implemented and the sensitivity of the cycle performance and the optimal design parameters is explored. Sensitivity of the cycle performance and optimal design parameters is studied with respect to the minimum heat rejection temperature and the maximum heat addition temperature. A hybrid stochastic and gradient based optimization technique has been used to optimize critical design parameters for maximum engine thermal efficiency. A parallel design exploration mode was also developed in order to rapidly conduct the parameter sweeps in this design space exploration. A cycle thermal efficiency of 49.6% is predicted with a 320K [47°C] minimum temperature and 923K [650°C] maximum temperature. The real fluid heat engine power cycle analysis code was expanded to study a theoretical recuperated Lenoir cycle using supercritical carbon dioxide as the working fluid. The real fluid cycle analysis code was also enhanced to study a combined cycle engine cascade. Two engine cascade configurations were studied. The first consisted of a traditional open loop gas turbine, coupled with a series of recuperated, recompression, precompression supercritical carbon dioxide power cycles, with a predicted combined cycle thermal efficiency of 65.0% using a peak temperature of 1,890K [1,617°C]. The second configuration consisted of a hybrid natural gas powered solid oxide fuel cell and gas turbine, coupled with a series of recuperated, recompression, precompression supercritical carbon dioxide power cycles, with a predicted combined cycle thermal efficiency of 73.1%. Both configurations had a minimum temperature of 306K [33°C]. The hybrid stochastic and gradient based optimization technique was used to optimize all engine design parameters for each engine in the cascade such that the entire engine cascade achieved the maximum thermal efficiency. The parallel design exploration mode was also utilized in order to understand the impact of different design parameters on the overall engine cascade thermal efficiency. Two dimensional conjugate heat transfer (CHT) numerical simulations of a straight, equal height channel heat exchanger using supercritical carbon dioxide were conducted at various Reynolds numbers and channel lengths.

  11. Inhomogeneous models of the Venus clouds containing sulfur

    NASA Technical Reports Server (NTRS)

    Smith, S. M.; Pollack, J. B.; Giver, L. P.; Cuzzi, J. N.; Podolak, M.

    1979-01-01

    Based on the suggestion that elemental sulfur is responsible for the yellow color of Venus, calculations are compared at 3.4 microns of the reflectivity phase function of two sulfur containing inhomogeneous cloud models with that of a homogeneous model. Assuming reflectivity observations with 25% or less total error, comparison of the model calculations leads to a minimum detectable mass of sulfur equal to 7% of the mass of sulfuric acid for the inhomogeneous drop model. For the inhomogeneous cloud model the comparison leads to a minimum detectable mass of sulfur between 17% and 38% of the mass of the acid drops, depending upon the actual size of the large particles. It is concluded that moderately accurate 3.4 microns reflectivity observations are capable of detecting quite small amounts of elemental sulfur at the top of the Venus clouds.

  12. Nonlinear Bubble Interactions in Acoustic Pressure Fields

    NASA Technical Reports Server (NTRS)

    Barbat, Tiberiu; Ashgriz, Nasser; Liu, Ching-Shi

    1996-01-01

    The systems consisting of a two-phase mixture, as clouds of bubbles or drops, have shown many common features in their responses to different external force fields. One of particular interest is the effect of an unsteady pressure field applied to these systems, case in which the coupling of the vibrations induced in two neighboring components (two drops or two bubbles) may result in an interaction force between them. This behavior was explained by Bjerknes by postulating that every body that is moving in an accelerating fluid is subjected to a 'kinetic buoyancy' equal with the product of the acceleration of the fluid multiplied by the mass of the fluid displaced by the body. The external sound wave applied to a system of drops/bubbles triggers secondary sound waves from each component of the system. These secondary pressure fields integrated over the surface of the neighboring drop/bubble may result in a force additional to the effect of the primary sound wave on each component of the system. In certain conditions, the magnitude of these secondary forces may result in significant changes in the dynamics of each component, thus in the behavior of the entire system. In a system containing bubbles, the sound wave radiated by one bubble at the location of a neighboring one is dominated by the volume oscillation mode and its effects can be important for a large range of frequencies. The interaction forces in a system consisting of drops are much smaller than those consisting of bubbles. Therefore, as a first step towards the understanding of the drop-drop interaction subject to external pressure fluctuations, it is more convenient to study the bubble interactions. This paper presents experimental results and theoretical predictions concerning the interaction and the motion of two levitated air bubbles in water in the presence of an acoustic field at high frequencies (22-23 KHz).

  13. Testing of a 4 K to 2 K heat exchanger with an intermediate pressure drop

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Knudsen, Peter N.; Ganni, Venkatarao

    2015-12-01

    Most large sub-atmospheric helium refrigeration systems incorporate a heat exchanger at the load, or in the distribution system, to counter-flow the sub-atmospheric return with the super-critical or liquid supply. A significant process improvement is theoretically obtainable by handling the exergy loss across the Joule-Thompson throttling valve supplying the flow to the load in a simple but different manner. As briefly outlined in previous publications, the exergy loss can be minimized by allowing the supply flow pressure to decrease to a sub-atmospheric pressure concurrent with heat exchange flow from the load. One practical implementation is to sub-divide the supply flow pressuremore » drop between two heat exchanger sections, incorporating an intermediate pressure drop. Such a test is being performed at Jefferson Lab's Cryogenic Test Facility (CTF). This paper will briefly discuss the theory, practical implementation and test results and analysis obtained to date.« less

  14. Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro

    2001-01-01

    This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.

  15. Investigating performance of microchannel evaporators for automobile air conditioning with different port structures

    NASA Astrophysics Data System (ADS)

    Zhou, Guoliang; Su, Lin; Cheng, Qia; Wu, Longbing

    2017-08-01

    Microchannel evaporator has been widely applied in automobile air conditioning, while it faces the problem of refrigerant maldistribution which deteriorates the thermal performance of evaporator. In this study, the performances of microchannel evaporators with different port structures are experimentally investigated for purpose of reducing evaporator pressure drop. Four evaporator samples with different port number and hydraulic diameter are made for this study. The performances of the evaporator samples are tested on a psychometric calorimeter test bench with the refrigerant R-134A at a real automobile air conditioning. The results on the variations of the evaporator pressure drop and evaporator surface temperature distribution are presented and analyzed. By studying the performance of an evaporator, seeking proper port structure is an approach to reduce refrigerant pressure drop as well as improve refrigerant distribution.

  16. Optimized Design of Spacer in Electrodialyzer Using CFD Simulation Method

    NASA Astrophysics Data System (ADS)

    Jia, Yuxiang; Yan, Chunsheng; Chen, Lijun; Hu, Yangdong

    2018-06-01

    In this study, the effects of length-width ratio and diversion trench of the spacer on the fluid flow behavior in an electrodialyzer have been investigated through CFD simulation method. The relevant information, including the pressure drop, velocity vector distribution and shear stress distribution, demonstrates the importance of optimized design of the spacer in an electrodialysis process. The results show width of the diversion trench has a great effect on the fluid flow compared with length. Increase of the diversion trench width could strength the fluid flow, but also increase the pressure drop. Secondly, the dead zone of the fluid flow decreases with increase of length-width ratio of the spacer, but the pressure drop increases with the increase of length-width ratio of the spacer. So the appropriate length-width ratio of the space should be moderate.

  17. Optimization of UA of heat exchangers and BOG compressor exit pressure of LNG boil-off gas reliquefaction system using exergy analysis

    NASA Astrophysics Data System (ADS)

    Kochunni, Sarun Kumar; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2015-12-01

    Boil-off gas (BOG) generation and its handling are important issues in Liquefied natural gas (LNG) value chain because of economic, environment and safety reasons. Several variants of reliquefaction systems of BOG have been proposed by researchers. Thermodynamic analyses help to configure them and size their components for improving performance. In this paper, exergy analysis of reliquefaction system based on nitrogen-driven reverse Brayton cycle is carried out through simulation using Aspen Hysys 8.6®, a process simulator and the effects of heat exchanger size with and without related pressure drop and BOG compressor exit pressure are evaluated. Nondimensionalization of parameters with respect to the BOG load allows one to scale up or down the design. The process heat exchanger (PHX) requires much higher surface area than that of BOG condenser and it helps to reduce the quantity of methane vented out to atmosphere. As pressure drop destroys exergy, optimum UA of PHX decreases for highest system performance if pressure drop is taken into account. Again, for fixed sizes of heat exchangers, as there is a range of discharge pressures of BOG compressor at which the loss of methane in vent minimizes, the designer should consider choosing the pressure at lower value.

  18. Passive blast pressure sensor

    DOEpatents

    King, Michael J.; Sanchez, Roberto J.; Moss, William C.

    2013-03-19

    A passive blast pressure sensor for detecting blast overpressures of at least a predetermined minimum threshold pressure. The blast pressure sensor includes a piston-cylinder arrangement with one end of the piston having a detection surface exposed to a blast event monitored medium through one end of the cylinder and the other end of the piston having a striker surface positioned to impact a contact stress sensitive film that is positioned against a strike surface of a rigid body, such as a backing plate. The contact stress sensitive film is of a type which changes color in response to at least a predetermined minimum contact stress which is defined as a product of the predetermined minimum threshold pressure and an amplification factor of the piston. In this manner, a color change in the film arising from impact of the piston accelerated by a blast event provides visual indication that a blast overpressure encountered from the blast event was not less than the predetermined minimum threshold pressure.

  19. NASA Glenn Icing Research Tunnel: 2014 Cloud Calibration Procedure and Results

    NASA Technical Reports Server (NTRS)

    Van Zante, Judith F.; Ide, Robert F.; Steen, Laura E.; Acosta, Waldo J.

    2014-01-01

    The results of the December 2013 to February 2014 Icing Research Tunnel full icing cloud calibration are presented. The calibration steps included establishing a uniform cloud and conducting drop size and liquid water content calibrations. The goal of the calibration was to develop a uniform cloud, and to generate a transfer function from the inputs of air speed, spray bar atomizing air pressure and water pressure to the outputs of median volumetric drop diameter and liquid water content. This was done for both 14 CFR Parts 25 and 29, Appendix C ('typical' icing) and soon-to-be released Appendix O (supercooled large drop) conditions.

  20. Pre-sheath density drop induced by ion-neutral friction along plasma blobs and implications for blob velocities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Furno, I.; Chabloz, V.; Fasoli, A.

    2014-01-15

    The pre-sheath density drop along the magnetic field in field-aligned, radially propagating plasma blobs is investigated in the TORPEX toroidal experiment [Fasoli et al., Plasma Phys. Controlled Fusion 52, 124020 (2010)]. Using Langmuir probes precisely aligned along the magnetic field, we measure the density n{sub se} at a poloidal limiter, where blobs are connected, and the upstream density n{sub 0} at a location half way to the other end of the blobs. The pre-sheath density drop n{sub se}/n{sub 0} is then computed and its dependence upon the neutral background gas pressure is studied. At low neutral gas pressures, the pre-sheathmore » density drop is ≈0.4, close to the value of 0.5 expected in the collisionless case. In qualitative agreement with a simple model, this value decreases with increasing gas pressure. No significant dependence of the density drop upon the radial distance into the limiter shadow is observed. The effect of reduced blob density near the limiter on the blob radial velocity is measured and compared with predictions from a blob speed-versus-size scaling law [Theiler et al., Phys. Rev. Lett. 103, 065001 (2009)].« less

  1. Influence of Peer Pressure on Secondary School Students Drop out in Rongo Sub-County, Migori County, Kenya

    ERIC Educational Resources Information Center

    Omollo, Atieno Evaline; Yambo, Onyango J. M.

    2017-01-01

    The purpose of this study was to establish the influence of peer pressure on secondary school students' drop out in Rongo Sub-County, Migori County, Kenya. The statement of the problem showed that the sub-county had a dropout rate of 43 percent as compared to the neighboring sub counties like Uriri, Awendo, Nyatike, Kuria and Migori which had 25,…

  2. Nanoengineered Surfaces for High Flux Thin Film Evaporation

    DTIC Science & Technology

    2013-07-15

    for a variety of heat transfer and resource conserving applications. References 1. Mudawar , I., Assessment of high-heat-flux thermal...M.B. and I. Mudawar , High-flux boiling in low-flow rate, low-pressure drop mini- channel and microchannel heat sinks. International Journal of Heat...pressure drop elements and fabricated nucleation sites. Journal of Heat Transfer, 2006. 128(4): p. 389-396. 7. Qu, W. and I. Mudawar , Measurement and

  3. Apparatus for providing directional permeability measurements in subterranean earth formations

    DOEpatents

    Shuck, Lowell Z.

    1977-01-01

    Directional permeability measurements are provided in a subterranean earth formation by injecting a high-pressure gas from a wellbore into the earth formation in various azimuthal directions with the direction having the largest pressure drop being indicative of the maximum permeability direction. These measurements are provided by employing an inflatable boot containing a plurality of conduits in registry with a like plurality of apertures penetrating the housing at circumferentially spaced-apart locations. These conduits are, in turn, coupled through a valved manifold to a source of pressurized gas so that the high-pressure gas may be selectively directed through any conduit into the earth formation defining the bore with the resulting difference in the pressure drop through the various conduits providing the permeability measurements.

  4. Two-phase adiabatic pressure drop experiments and modeling under micro-gravity conditions

    NASA Astrophysics Data System (ADS)

    Longeot, Matthieu J.; Best, Frederick R.

    1995-01-01

    Thermal systems for space applications based on two phase flow have several advantages over single phase systems. Two phase thermal energy management and dynamic power conversion systems have the capability of achieving high specific power levels. However, before two phase systems for space applications can be designed effectively, knowledge of the flow behavior in a ``0-g'' acceleration environment is necessary. To meet this need, two phase flow experiments were conducted by the Interphase Transport Phenomena Laboratory Group (ITP) aboard the National Aeronautics and Space Administration's (NASA) KC-135, using R12 as the working fluid. The present work is concerned with modeling of two-phase pressure drop under 0-g conditions, for bubbly and slug flow regimes. The set of data from the ITP group includes 3 bubbly points, 9 bubbly/slug points and 6 slug points. These two phase pressure drop data were collected in 1991 and 1992. A methodology to correct and validate the data was developed to achieve high levels of confidence. A homogeneous model was developed to predict the pressure drop for particular flow conditions. This model, which uses the Blasius Correlation, was found to be accurate for bubbly and bubbly/slug flows, with errors not larger than 28%. For slug flows, however, the errors are greater, attaining values up to 66%.

  5. Hydrological response to earthquakes in the Haibara well, central Japan - II. Possible mechanism inferred from time-varying hydraulic properties

    USGS Publications Warehouse

    Matsumoto, N.; Roeloffs, E.A.

    2003-01-01

    28 coseismic groundwater level decreases have been observed at the Haibara well, Shizuoka prefecture, central Japan, from 1981 to 1997. These groundwater level changes cannot be explained as the poroelastic response to coseismic static strain. We use the atmospheric pressure and tidal responses of the well, rock properties measured on core samples from the same formation and pumping test results to characterize the hydraulic and mechanical properties of the aquifer. The responses of the Haibara well to the M2 Earth tide constituent and to atmospheric pressure have varied over time. In particular, increasing amplitude and decreasing phase lags were observed after the 1993 pumping test, as well as after earthquakes that caused coseismic water level changes. The tidal response, together with the surface load efficiency derived from the atmospheric pressure response, is used to estimate the mechanical properties of the aquifer. The largest amplitude of the M2 constituent, 2.2 mm, is small enough to imply that pore fluid in this system is approximately twice as compressible as water, possibly due to the presence of a small amount of exsolved gas. Diffusion of a coseismic pressure drop near the well could account for the observed time histories of the water level changes. The time histories of the water level drops are well matched by the decay of a coseismic pressure drop at least 80 m away from the well. Removal of a small amount of gas from the formation in that location might in turn explain the coseismic pressure drops.

  6. Investigation on heat transfer characteristics and flow performance of Methane at supercritical pressures

    NASA Astrophysics Data System (ADS)

    Xian, Hong Wei; Oumer, A. N.; Basrawi, F.; Mamat, Rizalman; Abdullah, A. A.

    2018-04-01

    The aim of this study is to investigate the heat transfer and flow characteristic of cryogenic methane in regenerative cooling system at supercritical pressures. The thermo-physical properties of supercritical methane were obtained from the National institute of Standards and Technology (NIST) webbook. The numerical model was developed based on the assumptions of steady, turbulent and Newtonian flow. For mesh independence test and model validation, the simulation results were compared with published experimental results. The effect of four different performance parameter ranges namely inlet pressure (5 to 8 MPa), inlet temperature (120 to 150 K), heat flux (2 to 5 MW/m2) and mass flux (7000 to 15000 kg/m2s) on heat transfer and flow performances were investigated. It was found that the simulation results showed good agreement with experimental data with maximum deviation of 10 % which indicates the validity of the developed model. At low inlet temperature, the change of specific heat capacity at near-wall region along the tube length was not significant while the pressure drop registered was high. However, significant variation was observed for the case of higher inlet temperature. It was also observed that the heat transfer performance and pressure drop penalty increased when the mass flux was increased. Regarding the effect of inlet pressure, the heat transfer performance and pressure drop results decreased when the inlet pressure is increased.

  7. Low Blood Pressure (Hypotension)

    MedlinePlus

    ... Low blood pressure on standing up (orthostatic, or postural, hypotension). This is a sudden drop in blood ... progressive damage to the autonomic nervous system, which controls involuntary functions such as blood pressure, heart rate, ...

  8. Two types of Cassie-to-Wenzel wetting transitions on superhydrophobic surfaces during drop impact.

    PubMed

    Lee, Choongyeop; Nam, Youngsuk; Lastakowski, Henri; Hur, Janet I; Shin, Seungwon; Biance, Anne-Laure; Pirat, Christophe; Kim, Chang-Jin C J; Ybert, Christophe

    2015-06-21

    Despite the fact that superhydrophobic surfaces possess useful and unique properties, their practical application has remained limited by durability issues. Among those, the wetting transition, whereby a surface gets impregnated by the liquid and permanently loses its superhydrophobicity, certainly constitutes the most limiting aspect under many realistic conditions. In this study, we revisit this so-called Cassie-to-Wenzel transition (CWT) under the broadly encountered situation of liquid drop impact. Using model hydrophobic micropillar surfaces of various geometrical characteristics and high speed imaging, we identify that CWT can occur through different mechanisms, and at different impact stages. At early impact stages, right after contact, CWT occurs through the well established dynamic pressure scenario of which we provide here a fully quantitative description. Comparing the critical wetting pressure of surfaces and the theoretical pressure distribution inside the liquid drop, we provide not only the CWT threshold but also the hardly reported wetted area which directly affects the surface spoiling. At a later stage, we report for the first time to our knowledge, a new CWT which occurs during the drop recoil toward bouncing. With the help of numerical simulations, we discuss the mechanism underlying this new transition and provide a simple model based on impulse conservation which successfully captures the transition threshold. By shedding light on the complex interaction between impacting water drops and surface structures, the present study will facilitate designing superhydrophobic surfaces with a desirable wetting state during drop impact.

  9. On the determination of a generalized Darcy equation for yield stress fluid in porous media using a LB TRT scheme

    NASA Astrophysics Data System (ADS)

    Talon, Laurent; Chevalier, Thibaud

    2014-11-01

    Non-Newtonian fluids have practical applications in very different domains. Indeed, polymer mixture, paints, slurries, colloidal suspensions, emulsions, foams or heavy oil present complex rheologies. Among the large number of different non-Newtonian fluids an important class of behavior is represented by the yield-stress fluids, viz. fluids that require a minimum of stress to flow. Yield stress fluids are usually modelled as a Bingham fluid or by the Herschel-Bulkley equation. However, simulating flow of a Bingham fluid in porous media still remains a challenging task as the yield stress may significantly alter the numerical stability and precision. In the present work, we use a Lattice-Boltzmann TRT scheme to determine this type of flow in a synthetic porous medium or fracture. Different pressure drops ΔP have been applied in order to derive a generalization of the Darcy's equation. Three different scaling regimes can be distinguished when plotting the dimensionless flow rate q as function of the distance to the critical pressure ΔP - ΔPc . In this presentation, we will investigate the importance of the heterogeneities on those flowing regimes. ANR-12-MONU-0011.

  10. Influence of solidification on the impact of supercooled water drops onto cold surfaces

    NASA Astrophysics Data System (ADS)

    Li, Hai; Roisman, Ilia V.; Tropea, Cameron

    2015-06-01

    This study presents an experimental investigation of the impact of a supercooled drop onto hydrophilic and superhydrophobic substrates. The aim is to better understand the process of airframe icing caused by supercooled large droplets, which has been recently identified as a severe hazard in aviation. The Weber number and Reynolds number of the impinging drop ranged from 200 to 300 and from 2600 to 5800, respectively. Drop impact, spreading, and rebound were observed using a high-speed video system. The maximum spreading diameter of an impacting drop on hydrophilic surfaces was measured. The temperature effect on this parameter was only minor for a wide range of the drop and substrate temperatures. However, ice/water mixtures emerged when both the drop and substrate temperatures were below 0 °C. Similarly, drop rebound on superhydrophobic substrates was significantly hindered by solidification when supercooled drop impacted onto substrates below the freezing point. The minimum receding diameter and the speed of ice accretion on the substrate were measured for various wall temperatures. Both parameters increased almost linearly with decreasing wall temperature, but eventually leveled off beyond a certain substrate temperature. The rate of ice formation on the substrate was significantly higher than the growth rate of free ice dendrites, implying that multiple nucleation sites were present.

  11. Nonlinear oscillations of inviscid free drops

    NASA Technical Reports Server (NTRS)

    Patzek, T. W.; Benner, R. E., Jr.; Basaran, O. A.; Scriven, L. E.

    1991-01-01

    The present analysis of free liquid drops' inviscid oscillations proceeds through solution of Bernoulli's equation to obtain the free surface shape and of Laplace's equation for the velocity potential field. Results thus obtained encompass drop-shape sequences, pressure distributions, particle paths, and the temporal evolution of kinetic and surface energies; accuracy is verified by the near-constant drop volume and total energy, as well as the diminutiveness of mass and momentum fluxes across drop surfaces. Further insight into the nature of oscillations is provided by Fourier power spectrum analyses of mode interactions and frequency shifts.

  12. Parametric resonance in acoustically levitated water drops

    NASA Astrophysics Data System (ADS)

    Shen, C. L.; Xie, W. J.; Wei, B.

    2010-05-01

    Liquid drops can be suspended in air with acoustic levitation method. When the sound pressure is periodically modulated, the levitated drop is usually forced into an axisymmetric oscillation. However, a transition from axisymmetric oscillation into sectorial oscillation occurs when the modulation frequency approaches some specific values. The frequency of the sectorial oscillation is almost exactly half of the modulation frequency. It is demonstrated that this transition is induced by the parametric resonance of levitated drop. The natural frequency of sectorial oscillation is found to decrease with the increase of drop distortion extent.

  13. Measurement and modelling of forced convective heat transfer coefficient and pressure drop of Al2O3- and SiO2-water nanofluids

    NASA Astrophysics Data System (ADS)

    Julia, J. E.; Hernández, L.; Martínez-Cuenca, R.; Hibiki, T.; Mondragón, R.; Segarra, C.; Jarque, J. C.

    2012-11-01

    Forced convective heat transfer coefficient and pressure drop of SiO2- and Al2O3-water nanofluids were characterized. The experimental facility was composed of thermal-hydraulic loop with a tank with an immersed heater, a centrifugal pump, a bypass with a globe valve, an electromagnetic flow-meter, a 18 kW in-line pre-heater, a test section with band heaters, a differential pressure transducer and a heat exchanger. The test section consists of a 1000 mm long aluminium pipe with an inner diameter of 31.2 mm. Eighteen band heaters were placed all along the test section in order to provide a uniform heat flux. Heat transfer coefficient was calculated measuring fluid temperature using immersed thermocouples (Pt100) placed at both ends of the test section and surface thermocouples in 10 axial locations along the test section (Pt1000). The measurements have been performed for different nanoparticles (Al2O3 and SiO2 with primary size of 11 nm and 12 nm, respectively), volume concentrations (1% v., 5% v.), and flow rates (3 103Re<105). Maximum heat transfer coefficient enhancement (300%) and pressure drop penalty (1000%) is obtained with 5% v. SiO2 nanofluid. Existing correlations can predict, at least in a first approximation, the heat transfer coefficient and pressure drop of nanofluids if thermal conductivity, viscosity and specific heat were properly modelled.

  14. Firefighter's compressed air breathing system pressure vessel development program

    NASA Technical Reports Server (NTRS)

    Beck, E. J.

    1974-01-01

    The research to design, fabricate, test, and deliver a pressure vessel for the main component in an improved high-performance firefighter's breathing system is reported. The principal physical and performance characteristics of the vessel which were required are: (1) maximum weight of 9.0 lb; (2) maximum operating pressure of 4500 psig (charge pressure of 4000 psig); (3) minimum contained volume of 280 in. 3; (4) proof pressure of 6750 psig; (5) minimum burst pressure of 9000 psig following operational and service life; and (6) a minimum service life of 15 years. The vessel developed to fulfill the requirements described was completely sucessful, i.e., every category of performence was satisfied. The average weight of the vessel was found to be about 8.3 lb, well below the 9.0 lb specification requirement.

  15. Modified friction factor correlation for CICC's based on a porous media analogy

    NASA Astrophysics Data System (ADS)

    Lewandowska, Monika; Bagnasco, Maurizio

    2011-09-01

    A modified correlation for the bundle friction factor in CICC's based on a porous media analogy is presented. The correlation is obtained by the analysis of the collected pressure drop data measured for 23 CICC's. The friction factors predicted by the proposed correlation are compared with those resulting from the pressure drop data for two CICC's measured recently using cryogenic helium in the SULTAN test facility at EPFL-CRPP.

  16. Fluid mechanics relevant to flow through pretreatment of cellulosic biomass.

    PubMed

    Archambault-Léger, Véronique; Lynd, Lee R

    2014-04-01

    The present study investigates fluid mechanical properties of cellulosic feedstocks relevant to flow through (FT) pretreatment for biological conversion of cellulosic biomass. The results inform identifying conditions for which FT pretreatment can be implemented in a practical context. Measurements of pressure drop across packed beds, viscous compaction and water absorption are reported for milled and not milled sugarcane bagasse, switchgrass and poplar, and important factors impacting viscous flow are deduced. Using biomass knife-milled to pass through a 2mm sieve, the observed pressure drop was highest for bagasse, intermediate for switchgrass and lowest for poplar. The highest pressure drop was associated with the presence of more fine particles, greater viscous compaction and the degree of water absorption. Using bagasse without particle size reduction, the instability of the reactor during pretreatment above 140kg/m(3) sets an upper bound on the allowable concentration for continuous stable flow. Copyright © 2014. Published by Elsevier Ltd.

  17. Effect of electrode intrusion on pressure drop and electrochemical performance of an all-vanadium redox flow battery

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Jayanti, S.

    2017-08-01

    In this paper, we present a study of the effect of electrode intrusion into the flow channel in an all-vanadium redox flow battery. Permeability, pressure drop and electrochemical performance have been measured in a cell with active area 100 cm2and 414 cm2 fitted with a carbon felt electrode of thickness of 3, 6 or 9 mm compressed to 1.5, 2.5 or 4 mm, respectively, during assembly. Results show that the pressure drop is significantly higher than what can be expected in the thick electrode case while its electrochemical performance is lower. Detailed flow analysis using computational fluid dynamics simulations in two different flow fields shows that both these results can be attributed to electrode intrusion into the flow channel leading to increased resistance to electrolyte flow through the electrode. A correlation is proposed to evaluate electrode intrusion depth as a function of compression.

  18. Architecture for improved mass transport and system performance in redox flow batteries

    NASA Astrophysics Data System (ADS)

    Houser, Jacob; Pezeshki, Alan; Clement, Jason T.; Aaron, Douglas; Mench, Matthew M.

    2017-05-01

    In this work, electrochemical performance and parasitic losses are combined in an overall system-level efficiency metric for a high performance, all-vanadium redox flow battery. It was found that pressure drop and parasitic pumping losses are relatively negligible for high performance cells, i.e., those capable of operating at a high current density while at a low flow rate. Through this finding, the Equal Path Length (EPL) flow field architecture was proposed and evaluated. This design has superior mass transport characteristics in comparison with the standard serpentine and interdigitated designs at the expense of increased pressure drop. An Aspect Ratio (AR) design is discussed and evaluated, which demonstrates decreased pressure drop compared to the EPL design, while maintaining similar electrochemical performance under most conditions. This AR design is capable of leading to improved system energy efficiency for flow batteries of all chemistries.

  19. Thermal design, rating and second law analysis of shell and tube condensers based on Taguchi optimization for waste heat recovery based thermal desalination plants

    NASA Astrophysics Data System (ADS)

    Chandrakanth, Balaji; Venkatesan, G; Prakash Kumar, L. S. S; Jalihal, Purnima; Iniyan, S

    2018-03-01

    The present work discusses the design and selection of a shell and tube condenser used in Low Temperature Thermal Desalination (LTTD). To optimize the key geometrical and process parameters of the condenser with multiple parameters and levels, a design of an experiment approach using Taguchi method was chosen. An orthogonal array (OA) of 25 designs was selected for this study. The condenser was designed, analysed using HTRI software and the heat transfer area with respective tube side pressure drop were computed using the same, as these two objective functions determine the capital and running cost of the condenser. There was a complex trade off between the heat transfer area and pressure drop in the analysis, however second law analysis was worked out for determining the optimal heat transfer area vs pressure drop for condensing the required heat load.

  20. Selective laser melting in heat exchanger development - experimental investigation of heat transfer and pressure drop characteristics of wavy fins

    NASA Astrophysics Data System (ADS)

    Kuehndel, J.; Kerler, B.; Karcher, C.

    2018-04-01

    To improve performance of heat exchangers for vehicle applications, it is necessary to increase the air side heat transfer. Selective laser melting gives rise to be applied for fin development due to: i) independency of conventional tooling ii) a fast way to conduct essential experimental studies iii) high dimensional accuracy iv) degrees of freedom in design. Therefore, heat exchanger elements with wavy fins were examined in an experimental study. Experiments were conducted for air side Reynolds number range of 1400-7400, varying wavy amplitude and wave length of the fins at a constant water flow rate of 9.0 m3/h. Heat transfer and pressure drop characteristics were evaluated with Nusselt Number Nu and Darcy friction factor ψ as functions of Reynolds number. Heat transfer and pressure drop correlations were derived from measurement data obtained by regression analysis.

  1. Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

    2006-01-01

    The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

  2. Effect of Exit-Slot Position and Opening on the Available Cooling Pressure for NACA Nose-Slot Cowlings

    NASA Technical Reports Server (NTRS)

    Stickle, George W; Naiman, Irven; Crigler, John L

    1940-01-01

    Report presents the results of an investigation of full-scale nose-slot cowlings conducted in the NACA 20-foot wind tunnel to furnish information on the pressure drop available for cooling. Engine conductances from 0 to 0.12 and exit-slot conductances from 0 to 0.30 were covered. Two basic nose shapes were tested to determine the effect of the radius of curvature of the nose contour; the nose shape with the smaller radius of curvature gave the higher pressure drop across the engine. The best axial location of the slot for low-speed operation was found to be in the region of maximum negative pressure for the basic shape for the particular operating condition. The effect of the pressure operating condition on the available cooling pressure is shown.

  3. Synergistic action of starch and honey against Candida albicans in correlation with diastase number

    PubMed Central

    Boukraa, Laïd; Benbarek, Hama; Moussa, Ahmed

    2008-01-01

    To evaluate the synergistic action of starch on the antifungal activity of honey, a comparative method of adding honey with and without starch to culture media was used. Candida albicans has been used to determine the minimum inhibitory concentration (MIC) of five varieties of honey. In a second step, lower concentrations of honey than the MIC were incubated with a set of concentrations of starch added to media to determine the minimum synergistic inhibitory concentration (MSIC). The MIC for the five varieties of honey without starch against C. albicans ranged between 40% and 45% (v/v). When starch was incubated with honey and then added to media, a MIC drop has been noticed with each variety. It ranged between 7% and 25%. A negative correlation has been established between the MIC drop and the diastase number (DN). PMID:24031175

  4. Effect of swirler-mounted mixing venturi on emissions of flame-tube combustor using jet A fuel

    NASA Technical Reports Server (NTRS)

    Ercegovic, D. B.

    1979-01-01

    Six headplate modules in a flame-tube combustor were evaluated. Unburned hydrocarbons, carbon monoxide, and oxides of nitrogen were measured for three types of fuel injectors both with and without a mixing venturi. Tests were conducted using jet A fuel at an inlet pressure of 0.69 megapascal, an inlet temperature of 478 K, and an isothermal static pressure drop of 3 percent. Oxides of nitrogen were reduced by over 50 percent with a mixing venturi with no performance penalties in either other gaseous emissions or pressure drop.

  5. Hanging drop crystal growth apparatus and method

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor); Smith, Robbie E. (Inventor)

    1989-01-01

    An apparatus (10) is constructed having a cylindrical enclosure (16) within which a disc-shaped wicking element (18) is positioned. A well or recess (22) is cut into an upper side (24) of this wicking element, and a glass cover plate or slip (28) having a protein drop disposed thereon is sealably positioned on the wicking element (18), with drop (12) being positioned over well or recess (22). A flow of control fluid is generated by a programmable gradient former (16), with this control fluid having a vapor pressure that is selectively variable. This flow of control fluid is coupled to the wicking element (18) where control fluid vapor diffusing from walls (26) of the recess (22) is exposed to the drop (12), forming a vapor pressure gradient between the drop (12) and the control fluid vapor. Initially, this gradient is adjusted to draw solvent from the drop (12) at a relatively high rate, and as the critical supersaturation point is approached (the point at which crystal nucleation occurs), the gradient is reduced to more slowly draw solvent from the drop (12). This allows discrete protein molecules more time to orient themselves into an ordered crystalline lattice, producing protein crystals which, when processed by X-ray crystallography, possess a high degree of resolution.

  6. Experimental investigation of MHD pressure losses in a mock-up of a liquid metal blanket

    NASA Astrophysics Data System (ADS)

    Mistrangelo, C.; Bühler, L.; Brinkmann, H.-J.

    2018-03-01

    Experiments have been performed to investigate the influence of a magnetic field on liquid metal flows in a scaled mock-up of a helium cooled lead lithium (HCLL) blanket. During the experiments pressure differences between points on the mock-up have been recorded for various values of flow rate and magnitude of the imposed magnetic field. The main contributions to the total pressure drop in the test-section have been identified as a function of characteristic flow parameters. For sufficiently strong magnetic fields the non-dimensional pressure losses are practically independent on the flow rate, namely inertia forces become negligible. Previous experiments on MHD flows in a simplified test-section for a HCLL blanket showed that the main contributions to the total pressure drop in a blanket module originate from the flow in the distributing and collecting manifolds. The new experiments confirm that the largest pressure drops occur along manifolds and near the first wall of the blanket module, where the liquid metal passes through small openings in the stiffening plates separating two breeder units. Moreover, the experimental data shows that with the present manifold design the flow does not distribute homogeneously among the 8 stacked boxes that form the breeding zone.

  7. Liquid jet response to internal modulated ultrasonic radiation pressure and stimulated drop production.

    PubMed

    Lonzaga, Joel B; Osterhoudt, Curtis F; Thiessen, David B; Marston, Philip L

    2007-06-01

    Experimental evidence shows that a liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. Ultrasound applied to the jet supply liquid can propagate within the jet when the acoustic frequency is near to or above the cutoff frequency. Modulated radiation pressure is used to stimulate large amplitude deformations and the breakup of the jet into drops. The jet response to the modulated internal ultrasonic radiation pressure was monitored along the jet using (a) an optical extinction method and (b) images captured by a video camera. The jet profile oscillates at the frequency of the radiation pressure modulation and where the response is small, the amplitude was found to increase in proportion to the square of the acoustic pressure amplitude as previously demonstrated for oscillating drops [P.L. Marston and R.E. Apfel, J. Acoust. Soc. Am. 67, 27-37 (1980)]. Small amplitude deformations initially grow approximately exponentially with axial distance along the jet. Though aspects of the perturbation growth can be approximated from Rayleigh's analysis of the capillary instability, some detailed features of the observed jet response to modulated ultrasound are unexplained neglecting the effects of gravity.

  8. The impact of wall shear stress and pressure drop on the stability of the atherosclerotic plaque.

    PubMed

    Li, Zhi-Yong; Taviani, Valentina; Gillard, Jonathan H

    2008-01-01

    Rupture of vulnerable atheromatous plaque in the carotid and coronary arteries often leads to stroke and heart attack respectively. The mechanism of blood flow and plaque rupture in stenotic arteries is still not fully understood. A three dimensional rigid wall model was solved under steady state conditions and unsteady conditions by assuming a time-varying inlet velocity profile to investigate the relative importance of axial forces and pressure drops in arteries with asymmetric stenosis. Flow-structure interactions were investigated for the same geometry and the results were compared with those retrieved with the corresponding 2D cross-section structural models. The Navier-Stokes equations were used as the governing equations for the fluid. The tube wall was assumed hyperelastic, homogeneous, isotropic and incompressible. The analysis showed that the three dimensional behavior of velocity, pressure and wall shear stress is in general very different from that predicted by cross-section models. Pressure drop across the stenosis was found to be much higher than shear stress. Therefore, pressure may be the more important mechanical trigger for plaque rupture other than shear stress, although shear stress is closely related to plaque formation and progression.

  9. Correlation of current drop, filling gas pressure, and ion beam emission in a low energy Mather-type plasma focus device

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Behbahani, R. A.; Aghamir, F. M.

    The behavior of current drop and its correlation with ion beam emission during the radial phase of a high inductance low energy Mather type plasma focus device have been studied. The study includes two ranges of filling gas pressure, namely the low range of 0.2-0.8 mbar and the high range of 0.8-1.5 mbar. Two different current simulation processes were performed to aid the interpretation of the experimental results. Within the low range of operating pressure, an acceptable match between the computed and experimental current signals was achieved when the effects of anomalous resistances were contemplated. While in the high rangemore » of pressure, the computed and experimental current traces were in line even without considering the effects of anomalous resistances. The analysis shows that by decreasing the filling gas pressure the effects of instabilities are intensified. The computed and experimental current traces, along with ion beam signals gathered from a faraday cup, show that there is a strong correlation between the intensity of ion beam and its duration with the current drop during the radial phase.« less

  10. Preliminary kinetic evaluation of an immobilized polysaccharide sub-2μm column using a low dispersion supercritical fluid chromatograph.

    PubMed

    Berger, Terry A

    2017-08-11

    The performance of a 3×50mm, 1.6μm d p column with an immobilized polysaccharide stationary phase (ChiralPak IA-U) was evaluated for efficiency, and pressure drop, with respect to flow rate and modifier concentration using supercritical fluid chromatography (SFC). This appears to be the first such report using such a column in SFC. A unique low dispersion (ultra-high performance) SFC was used for the evaluation. The minimum reduced plate height of 2.78, indicates that the maximum efficiency was similar to or better than coated polysaccharide columns. Selectivity was different from ChiralPak AD, with the same chiral selector, as reported by many others. At high flows and high methanol concentrations, pump pressures sometimes approached 600bar. With 5% methanol, pressure vs. flow rate was non-linear suggesting turbulent flow in the connector tubing. The optimum flow rate (F opt ) at 40% methanol was ≈0.8mL/min, where the column efficiency was highest. At 5% methanol, F opt increased to ≈1.6mL/min, but efficiency degraded noticeably. The differences in F opt suggests that the solute diffusion coefficients are a strong function of modifier concentration. Several sub-1min separations, including a 7.5s separation, are presented. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Drop impact on spherical soft surfaces

    NASA Astrophysics Data System (ADS)

    Chen, Simeng; Bertola, Volfango

    2017-08-01

    The impact of water drops on spherical soft surfaces is investigated experimentally through high-speed imaging. The effect of a convex compliant surface on the dynamics of impacting drops is relevant to various applications, such as 3D ink-jet printing, where drops of fresh material impact on partially cured soft substrates with arbitrary shape. Several quantities which characterize the morphology of impacting drops are measured through image-processing, including the maximum and minimum spreading angles, length of the wetted curve, and dynamic contact angle. In particular, the dynamic contact angle is measured using a novel digital image-processing scheme based on a goniometric mask, which does not require edge fitting. It is shown that the surface with a higher curvature enhances the retraction of the spreading drop; this effect may be due to the difference of energy dissipation induced by the curvature of the surface. In addition, the impact parameters (elastic modulus, diameter ratio, and Weber number) are observed to significantly affect the dynamic contact angle during impact. A quantitative estimation of the deformation energy shows that it is significantly smaller than viscous dissipation.

  12. Prediction of orthostatic hypotension in multiple system atrophy and Parkinson disease

    PubMed Central

    Sun, Zhanfang; Jia, Dandan; Shi, Yuting; Hou, Xuan; Yang, Xiaosu; Guo, Jifeng; Li, Nan; Wang, Junling; Sun, Qiying; Zhang, Hainan; Lei, Lifang; Shen, Lu; Yan, Xinxiang; Xia, Kun; Jiang, Hong; Tang, Beisha

    2016-01-01

    Orthostatic hypotension (OH) is common in multiple system atrophy (MSA) and Parkinson disease (PD), generally assessed through a lying-to-standing orthostatic test. However, standing blood pressure may not be available due to orthostatic intolerance or immobilization for such patients. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were successively measured in supine, sitting, and standing positions in patients with MSA and PD. Receiver operating characteristic analysis was used to evaluate diagnostic performance of the drops of sitting SBP or DBP. OH and severe OH were respectively regarded as “gold standard”. The drops of SBP in standing position were associated with increased disease severity for MSA and correlated with age for PD. In MSA group, drops in sitting SBP ≥ 14 mmHg or DBP ≥ 6 mmHg had highest validity for prediction of OH, and drops in sitting SBP ≥ 18 mmHg or DBP ≥ 8 mmHg for severe OH. In PD group, drops in sitting SBP ≥ 10 mmHg or DBP ≥ 6 mmHg had highest validity for prediction of OH. The lying-to-sitting orthostatic test is an alternative method for detection of OH in MSA and PD, especially when standing BP could not be validly measured due to various reasons. PMID:26867507

  13. Modeling contact angle hysteresis of a liquid droplet sitting on a cosine wave-like pattern surface.

    PubMed

    Promraksa, Arwut; Chen, Li-Jen

    2012-10-15

    A liquid droplet sitting on a hydrophobic surface with a cosine wave-like square-array pattern in the Wenzel state is simulated by using the Surface Evolver to determine the contact angle. For a fixed drop volume, multiple metastable states are obtained at two different surface roughnesses. Unusual and non-circular shape of the three-phase contact line of a liquid droplet sitting on the model surface is observed due to corrugation and distortion of the contact line by structure of the roughness. The contact angle varies along the contact line for each metastable state. The maximum and minimum contact angles among the multiple metastable states at a fixed viewing angle correspond to the advancing and the receding contact angles, respectively. It is interesting to observe that the advancing/receding contact angles (and contact angle hysteresis) are a function of viewing angle. In addition, the receding (or advancing) contact angles at different viewing angles are determined at different metastable states. The contact angle of minimum energy among the multiple metastable states is defined as the most stable (equilibrium) contact angle. The Wenzel model is not able to describe the contact angle along the three-phase contact line. The contact angle hysteresis at different drop volumes is determined. The number of the metastable states increases with increasing drop volume. Drop volume effect on the contact angles is also discussed. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

  14. Altitude Cooling Investigation of the R-2800-21 Engine in the P-47G Airplane. IV - Engine Cooling-Air Pressure Distribution

    NASA Technical Reports Server (NTRS)

    Kaufman, Samuel J.; Staudt, Robert C.; Valerino, Michael F.

    1947-01-01

    A study of the data obtained in a flight investigation of an R-2800-21 engine in a P-47G airplane was made to determine the effect of the flight variables on the engine cooling-air pressure distribution. The investigation consisted of level flights at altitudes from 5000 to 35,000 feet for the normal range of engine and airplane operation. The data showed that the average engine front pressures ranged from 0.73 to 0.82 of the impact pressure (velocity head). The average engine rear pressures ranged from 0.50 to 0.55 of the impact pressure for closed cowl flaps and from 0.10 to 0.20 for full-open cowl flaps. In general, the highest front pressures were obtained at the bottom of the engine. The rear pressures for the rear-row cylinders were .lower and the pressure drops correspondingly higher than for the front-row cylinders. The rear-pressure distribution was materially affected by cowl-flap position in that the differences between the rear pressures of the front-row and rear-row cylinders markedly increased as the cowl flaps were opened. For full-open cowl flaps, the pressure drops across the rear-row cylinders were in the order of 0.2 of the impact pressure greater than across the front-row cylinders. Propeller speed and altitude had little effect on the -coolingair pressure distribution, Increase in angle of inclination of the thrust axis decreased the front ?pressures for the cylinders at the top of the engine and increased them for the cylinders at the bottom of the engine. As more auxiliary air was taken from the engine cowling, the front pressures and, to a lesser extent, the rear pressures for the cylinders at the bottom of the engine decreased. No correlation existed between the cooling-air pressure-drop distribution and the cylinder-temperature distribution.

  15. Experimental study of the effect of drag reducing agent on pressure drop and thermal efficiency of an air cooler

    NASA Astrophysics Data System (ADS)

    Peyghambarzadeh, S. M.; Hashemabadi, S. H.; Saffarian, H.; Shekari, F.

    2016-01-01

    Effect of polymeric drag reduction agents (DRAs) on pressure drop and heat transfer was studied. Aqueous solutions of carboxy methyl cellulose were used inside an air-finned heat exchanger. Despite the previous studies which indicated the importance of drag reduction just in turbulent flow, results of this study in laminar flow indicated that the addition of DRA increases drag reduction, and decreases the overall heat transfer coefficient.

  16. Theoretical and experimental evaluation of the effects of an argon gas mixture on the pressure drop through adult tracheobronchial airway replicas.

    PubMed

    Litwin, Patrick D; Reis Dib, Anna Luisa; Chen, John; Noga, Michelle; Finlay, Warren H; Martin, Andrew R

    2017-06-14

    Argon has the potential to be a novel inhaled therapeutic agent, owing to the neuroprotective and organoprotective properties demonstrated in preclinical studies. Before human trials are performed, an understanding of varying gas properties on airway resistance during inhalation is essential. This study predicts the effect of an 80% argon/20% oxygen gas mixture on the pressure drop through conducting airways, and by extension the airway resistance, and then verifies these predictions experimentally using 3-D printed adult tracheobronchial airway replicas. The predicted pressure drop was calculated using established analytical models of airway resistance, incorporating the change in viscosity and density of the 80% argon/20% oxygen mixture versus that of air. Predicted pressure drop for the argon mixture increased by approximately 29% compared to that for air. The experimental results were consistent with this prediction for inspiratory flows ranging from 15 to 90slpm. These results indicate that established analytical models may be used to predict increases in conducting airway resistance for argon/oxygen mixtures, compared with air. Such predictions are valuable in predicting average patient response to breathing argon/oxygen mixtures, and in selecting or designing delivery systems for use in administration of argon/oxygen mixtures to critically ill or injured patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Characterisation and optimisation of flexible transfer lines for liquid helium. Part I: Experimental results

    NASA Astrophysics Data System (ADS)

    Dittmar, N.; Haberstroh, Ch.; Hesse, U.; Krzyzowski, M.

    2016-04-01

    The transfer of liquid helium (LHe) into mobile dewars or transport vessels is a common and unavoidable process at LHe decant stations. During this transfer reasonable amounts of LHe evaporate due to heat leak and pressure drop. Thus generated helium gas needs to be collected and reliquefied which requires a huge amount of electrical energy. Therefore, the design of transfer lines used at LHe decant stations has been optimised to establish a LHe transfer with minor evaporation losses which increases the overall efficiency and capacity of LHe decant stations. This paper presents the experimental results achieved during the thermohydraulic optimisation of a flexible LHe transfer line. An extensive measurement campaign with a set of dedicated transfer lines equipped with pressure and temperature sensors led to unique experimental data of this specific transfer process. The experimental results cover the heat leak, the pressure drop, the transfer rate, the outlet quality, and the cool-down and warm-up behaviour of the examined transfer lines. Based on the obtained results the design of the considered flexible transfer line has been optimised, featuring reduced heat leak and pressure drop.

  18. The effect of passive mixing on pressure drop and oxygen mass fraction using opposing channel flow field design in a Proton Exchange Membrane Fuel Cell

    NASA Astrophysics Data System (ADS)

    Singh, Anant Bir

    This study investigates a flow field with opposing channel design. Previous studies on flow field designs have been focused on improving fuel utilization which often leads to increased pressure drop. This increased pressure drop is typical because standard designs employ either a single flow channel to clear blockages or dead end condition to force the flow through the gas diffusion layer. The disadvantage with these designs is the increased resistance to the flow which requires higher pressure, which becomes a parasitic loss that lowers the system efficiency. For this study the focus was to reduce the pressure drop by providing a less resistive path to the flow. To achieve a less resistive path, the inlet channel was split into two opposing channels. These channels are then recombined only to be split again for the next leg. Therefore, the split channel design should reduce the pressure drop which reduces the parasitic load and ultimately contributes to higher system efficiency. In addition the recombining of the streams at each leg should induce mixing. Having opposing channels should also increase cross flow under the lands to reduce mass transfer loses. The cathode side of the fuel cell is especially sensitive to the mass transport losses since air (oxygen mixed with nitrogen) is used for supplying oxygen unlike the anode side which uses pure hydrogen. To test the hypothesis of having benefits from an opposing channel design, both an experimental and analytical approach was taken. For the experiment, a serpentine flow field and opposing channel flow field plates were compared over several flow rates with compressed air. To test the hypothesis of increased mass transfer, the two flow fields were modeled using a CFD software package, COMSOL. It was found that the opposing channel configuration for high flow rate with multiple entry and exit conditions exhibited significant improvement over the single serpentine channel. Pressure drop was ⅓ less than the serpentine channel with similar conditions. Simulations for mass transfer show that recombining of the flow streams generate more uniform current density unlike the serpentine configuration where the current density was concentrated at the entrance of the flow stream. The background section provides a brief overview of the governing equations, the theory of flow field operation and previous bodies of work on flow field design. Recommendations are made for further verification of the design using a real working cell based on the results.

  19. Static shape of an acoustically levitated drop with wave-drop interaction

    NASA Astrophysics Data System (ADS)

    Lee, C. P.; Anilkumar, A. V.; Wang, T. G.

    1994-11-01

    The static shape of a drop levitated and flattened by an acoustic standing wave field in air is calculated, requiring self-consistency between the drop shape and the wave. The wave is calculated for a given shape using the boundary integral method. From the resulting radiation stress on the drop surface, the shape is determined by solving the Young-Laplace equation, completing an iteration cycle. The iteration is continued until both the shape and the wave converge. Of particular interest are the shapes of large drops that sustain equilibrium, beyond a certain degree of flattening, by becoming more flattened at a decreasing sound pressure level. The predictions for flattening versus acoustic radiation stress, for drops of different sizes, compare favorably with experimental data.

  20. Pressure Reducer for Coal Gasifiers

    NASA Technical Reports Server (NTRS)

    Kendall, James M., Sr.

    1983-01-01

    Quasi-porous-plug pressure reducer is designed for gases containing abrasive particles. Gas used to generate high pressure steam to drive electric power generators. In giving up heat to steam, gas drops in temperature. Device used for coal gasification plants.

  1. Heterogeneous Nucleation Induced by Capillary Wave During Acoustic Levitation

    NASA Astrophysics Data System (ADS)

    Lü, Yong-Jun; Xie, Wen-Jun; Wei, Bing-Bo

    2003-08-01

    The rapid solidification of acoustically levitated drops of Pb-61.9 wt.%Sn eutectic alloy is accomplished. A surface morphology of spreading ripples is observed on a sample undercooled by 15 K. The ripples originate from the centre of sample surface, which is also the heterogeneous nucleation site for eutectic growth. The Faraday instability excited by forced surface vibration has brought about these ripples. They are retained in the solidified sample if the sound pressure level exceeds the threshold pressure required for the appearance of capillary waves. Theoretical calculations indicate that both the pressure and displacement maxima exist in the central part of a levitated drop. The pressure near the sample centre can promote heterogeneous nucleation, which is in agreement qualitatively with the experimental results.

  2. New results of the post-spinel transition pressure in Mg2SiO4 by means of in-situ X-ray diffraction in a multi-anvil press: complete agreement with the 660-km discontinuity depth

    NASA Astrophysics Data System (ADS)

    Ishii, T.; Huang, R.; Fei, H.; Koemets, I.; Liu, Z.; Maeda, F.; Yuan, L.; Wang, L.; Druzhbin, D.; Yamamoto, T.; Bhat, S.; Farla, R. J.; Kawazoe, T.; Tsujino, N.; Kulik, E.; Higo, Y.; Tange, Y.; Katsura, T.

    2017-12-01

    It has been accepted that the 660-km discontinuity (D660) is caused by the post-spinel (Psp) transition, which is decomposition of ringwoodite (Rw) to bridgmanite (Brg) + ferropericlase. Nevertheless, all of in-situ X-ray diffraction studies with multi-anvil presses (MAP) gave distinctively lower transition pressures than that of the D660 (23.4 GPa). Although Fei et al. (2004) claimed that their Psp transition pressure explains the D660, it is still 0.5 GPa lower by considering the geotherm. If these results were accepted, the Psp would not account for the D660. In this study, we re-investigated the Psp transition pressure in Mg2SiO4 by in-situ X-ray diffraction using a MAP. A fine-grained mixture of forsterite, enstatite and periclase (Pc) and an MgO pressure marker were placed at the center of a furnace. The sample was compressed to 6-7 MN and heated to 1100 K to synthesize a mixture of Rw, akimotoite and Pc. After that, more press load was applied to obtain sample pressures of ca. 23 GPa, and the sample was then heated to 1700 K, keeping this temperature for 1-2 hours. During keeping the temperature, the press load was first rapidly, and then gradually increased to prevent pressure drop. Phase identification and pressure determination were conducted with alternatively accumulated diffraction patterns of the sample and pressure maker. We bracketed the transition pressures by 23.7 and 24.0 GPa at 1700 K based on the third-order Birch-Murnaghan and Vinet EOSs of MgO given by Tange et al. (2009), respectively. The transition pressure at 2000 K is estimated to be 23.2-23.5 GPa by applying the Psp transition slope based on Fei et al. (2004). Thus, the present transition pressure completely agrees with the D660 depth. The reason for the lower transition pressures by the previous studies is pressure drop during heating. Although the transition completes at the beginning of target temperature, pressure significantly drops during or even before accumulating a diffraction pattern for 3-5 minutes. We obtained the correct transition pressure by preventing the pressure drop by pumping. This problem should be omnipresent in high P-T in-situ X-ray diffraction experiments to determine a phase boundary.

  3. Satellite observations of surface temperature during the March 2015 total solar eclipse.

    PubMed

    Good, Elizabeth

    2016-09-28

    The behaviour of remotely sensed land surface temperatures (LSTs) from the spinning-enhanced visible and infrared imager (SEVIRI) during the total solar eclipse of 20 March 2015 is analysed over Europe. LST is found to drop by up to several degrees Celcius during the eclipse, with the minimum LST occurring just after the eclipse mid-point (median=+1.5 min). The drop in LST is typically larger than the drop in near-surface air temperatures reported elsewhere, and correlates with solar obscuration (r=-0.47; larger obscuration = larger LST drop), eclipse duration (r=-0.62; longer duration = larger LST drop) and time (r=+0.37; earlier eclipse = larger LST drop). Locally, the LST drop is also correlated with vegetation (up to r=+0.6), with smaller LST drops occurring over more vegetated surfaces. The LSTs at locations near the coast and at higher elevation are also less affected by the eclipse. This study covers the largest area and uses the most observations of eclipse-induced surface temperature drops to date, and is the first full characterization of satellite LST during an eclipse (known to the author). The methods described could be applied to Geostationary Operational Environmental Satellite (GOES) LST data over North America during the August 2017 total solar eclipse.This article is part of the themed issue 'Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse'. © 2016 The Author(s).

  4. Satellite observations of surface temperature during the March 2015 total solar eclipse

    PubMed Central

    2016-01-01

    The behaviour of remotely sensed land surface temperatures (LSTs) from the spinning-enhanced visible and infrared imager (SEVIRI) during the total solar eclipse of 20 March 2015 is analysed over Europe. LST is found to drop by up to several degrees Celcius during the eclipse, with the minimum LST occurring just after the eclipse mid-point (median=+1.5 min). The drop in LST is typically larger than the drop in near-surface air temperatures reported elsewhere, and correlates with solar obscuration (r=−0.47; larger obscuration = larger LST drop), eclipse duration (r=−0.62; longer duration = larger LST drop) and time (r=+0.37; earlier eclipse = larger LST drop). Locally, the LST drop is also correlated with vegetation (up to r=+0.6), with smaller LST drops occurring over more vegetated surfaces. The LSTs at locations near the coast and at higher elevation are also less affected by the eclipse. This study covers the largest area and uses the most observations of eclipse-induced surface temperature drops to date, and is the first full characterization of satellite LST during an eclipse (known to the author). The methods described could be applied to Geostationary Operational Environmental Satellite (GOES) LST data over North America during the August 2017 total solar eclipse. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’. PMID:27550764

  5. 49 CFR 178.44 - Specification 3HT seamless steel cylinders for aircraft use.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with a water capacity (nominal) of not over 150 pounds and a service pressure of at least 900 psig. (b...., should be held to a minimum consistent with good high stress pressure vessel manufacturing practices. If... wall thickness must be such that the wall stress at the minimum specified test pressure may not exceed...

  6. 46 CFR 162.028-3 - Requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... which are subjected to pressure, exclusive of the hose, shall be at least five times the maximum working... which will withstand a minimum bursting pressure of 6,000 p.s.i., and a discharge hose or tube which will withstand a minimum bursting pressure of 5,000 p.s.i. The hose shall be constructed with either a...

  7. 46 CFR 162.028-3 - Requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... which are subjected to pressure, exclusive of the hose, shall be at least five times the maximum working... which will withstand a minimum bursting pressure of 6,000 p.s.i., and a discharge hose or tube which will withstand a minimum bursting pressure of 5,000 p.s.i. The hose shall be constructed with either a...

  8. 46 CFR 162.028-3 - Requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... which are subjected to pressure, exclusive of the hose, shall be at least five times the maximum working... which will withstand a minimum bursting pressure of 6,000 p.s.i., and a discharge hose or tube which will withstand a minimum bursting pressure of 5,000 p.s.i. The hose shall be constructed with either a...

  9. Nerve Fiber Layer Thickness and Characteristics Associated with Glaucoma in Community Living Older Adults: Prelude to a Screening Trial?

    PubMed

    Klein, Barbara E K; Johnson, Chris A; Meuer, Stacy M; Lee, Kyungmoo; Wahle, Andreas; Lee, Kristine E; Kulkarni, Amruta; Sonka, Milan; Abràmoff, Michael D; Klein, Ronald

    2017-04-01

    To examine the associations of nerve fiber layer (NFL) thickness with other ocular characteristics in older adults. Participants in the Beaver Dam Eye Study (2008-2010) underwent spectral domain optical coherence tomography (SD-OCT) scans of the optic nerve head, imaging of optic discs, frequency doubling technology (FDT) perimetry, measurement of intraocular pressure (IOP), and an interview concerning their history of glaucoma and use of drops to lower eye pressure. Self-reported histories of glaucoma and the use of drops to lower eye pressure were obtained at follow-up examinations (2014-2016). NFL thickness measured on OCTs varied by location around the optic nerve. Age was associated with mean NFL thickness. Mean NFL was thinnest in eyes with larger cup/disc (C/D) ratios. Horizontal hemifield defects or other optic nerve-field defects were associated with thinner NFL. NFL in persons who reported taking eye drops for high intraocular pressure was thinner compared to those not taking drops. After accounting for the presence of high intraocular pressure, large C/D ratios or hemifield defects, eyes with thinner NFL in the arcades were more likely (OR = 2.3 for 30 micron thinner NFL, p = 0.04) to have incident glaucoma at examination 5 years later. Retinal NFL thickness was associated with a new history of self-reported glaucoma 5 years later. A trial testing the usefulness of NFL as part of a screening battery for predicting glaucoma in those previously undiagnosed might lead to improved case finding and, ultimately, to diminishing the risk of visual field loss.

  10. Numerical study on self-cleaning canister filter with modified filter cap

    NASA Astrophysics Data System (ADS)

    Mohammed, Akmal Nizam; Zolkhaely, Mohd Hafiz; Sahrudin, Mohd Sahrizan; Razali, Mohd Azahari; Sapit, Azwan; Hushim, Mohd Faisal

    2017-04-01

    Air filtration system plays an important role in getting good quality air into turbo machinery such as gas turbine. The filtration system and filters improve the quality of air and protect the gas turbine parts from contaminants which could bring damage. This paper is focused on the configuration of the self-cleaning canister filter in order to obtain the minimal pressure drop along the filter. The configuration includes a modified canister filter cap that is based on the basic geometry that conforms to industry standard. This paper describes the use of CFD to simulate and analyze the flow through the filter. This tool is also used to monitor variables such as pressure and velocity along the filter and to visualize them in the form of contours, vectors and streamlines. In this study, the main parameter varied is the inlet velocity set in the boundary condition during simulations, which are 0.032, 0.063, 0.094 and 0.126 m/s respectively. The data obtained from simulations are then validated with reference data sourced from the industry, and comparisons have subsequently been made for these two filters. As a result, the improvement of the pressure drop for the modified filter is found to be 11.47% to 14.82% compared to the basic filter at the inlet velocity from 0.032 to 0.126 m/s. the total pressure drop produced is 292.3 Pa by the basic filter and 251.11 Pa for modified filter. The pressure drop reduction is 41.19 Pa, which is 14.1% from the basic filter.

  11. Oxygen and carbon dioxide transport in time-dependent blood flow past fiber rectangular arrays

    NASA Astrophysics Data System (ADS)

    Zierenberg, Jennifer R.; Fujioka, Hideki; Hirschl, Ronald B.; Bartlett, Robert H.; Grotberg, James B.

    2009-03-01

    The influence of time-dependent flows on oxygen and carbon dioxide transport for blood flow past fiber arrays arranged in in-line and staggered configurations was computationally investigated as a model for an artificial lung. Both a pulsatile flow, which mimics the flow leaving the right heart and passing through a compliance chamber before entering the artificial lung, and a right ventricular flow, which mimics flow leaving the right heart and directly entering the artificial lung, were considered in addition to a steady flow. The pulsatile flow was modeled as a sinusoidal perturbation superimposed on a steady flow while the right ventricular flow was modeled to accurately depict the period of flow acceleration (increasing flow) and deceleration (decreasing flow) during systole followed by zero flow during diastole. It was observed that the pulsatile flow yielded similar gas transport as compared to the steady flow, while the right ventricular flow resulted in smaller gas transport, with the decrease increasing with Re. The pressure drop across the fiber array (a measure of the resistance), work (an indicator of the work required of the right heart), and shear stress (a measure of potential blood cell activation and damage) are lowest for steady flow, followed by pulsatile flow, and then right ventricular flow. The pressure drop, work, shear stress, and Sherwood numbers (a measure of the gas transport efficiency) decrease with increasing porosity and are smaller for AR <1 as compared to AR >1 (AR is the distance between fibers in the flow direction/distance between fibers in direction perpendicular to flow), although for small porosities the Sherwood numbers are of similar magnitude. In general, for any fiber array geometry, high pressure drop, work, and shear stresses correlate with high Sherwood numbers, and low pressure drop, work, and shear stresses correlate with low Sherwood numbers creating a need for a compromise between pressure drop/work/shear stresses and gas transport.

  12. Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    O'Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

    2002-08-01

    A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numericalmore » modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.« less

  13. Shape oscillations of microparticles on an optical microscope stage.

    PubMed

    Zhu, Z M; Apfel, R E

    1985-11-01

    A modulated acoustic radiation pressure technique to produce quadrupole shape oscillations of drops ranging in diameter from 50-220 micron has been used by us. These drops have been suspended by acoustic levitation in a small chamber mounted on a stage of an optical microscope, which allowed easy viewing. The fission of drops and the deformation of sea urchin eggs were also observed.

  14. EFFECTS OF RAMADAN FASTING ON BLOOD PRESSURE IN NORMOTENSIVE MALES.

    PubMed

    Samad, Fatima; Qazi, Fahd; Pervaiz, Mohammad B; Kella, Danesh K; Mansoor, Maryah; Osmani, Bushra Z; Mir, Fazia; Kadir, Muhammad Masood

    2015-01-01

    Research has been done to investigate the effect of intermittent complete fasting on human physiological parameters but the effect of fasting on blood pressure remains relatively unexplored. Research in animal models suggests a hypotensive effect with an undetermined mechanism. Muslims worldwide fast daily from dawn to dusk throughout the Islamic month of Ramadan. This study was to investigate the proposed hypotensive effect of Ramadan fasting in males over A period of 20 days and to study the relationship of the pattern of blood pressure variation with body mass index change. A repeated measures observational study design was implemented with convenient sampling. Study group included 40 normotensive, non-smoker males with no known comorbidities between the ages of 18-40 who fasted daily in the month of Ramadan. One set of BP readings, each, was taken one week before the start of Ramadan and on the 7th, 14th and 21st day of Ramadan which included pre and post Iftar measurements along with other variables. Data was analysed by repeated measures ANOVA using SPSS. The differences were compared with critical values generated by Tukey's Method. There was a significant drop in systolic BP of 7.61 mmHg before Iftar, 2.72 mm-Hg after Iftar (p<0.005). There was a significant effect of Ramadan on diastolic BP (p<0.005), the drop being 3.19 mmHg. The drop in body mass index was significant only before Iftar at 0.3 kg/m2 (p<0.005). Pulse rate showed a significant drop of 7.79 bpm before Iftar and a significant rise of 3.96 bpm (p<0.005). Intermittent fasting causes a drop in both systolic and diastolic blood pressure in normotensive males.

  15. Developing a pressure ulcer risk factor minimum data set and risk assessment framework.

    PubMed

    Coleman, Susanne; Nelson, E Andrea; Keen, Justin; Wilson, Lyn; McGinnis, Elizabeth; Dealey, Carol; Stubbs, Nikki; Muir, Delia; Farrin, Amanda; Dowding, Dawn; Schols, Jos M G A; Cuddigan, Janet; Berlowitz, Dan; Jude, Edward; Vowden, Peter; Bader, Dan L; Gefen, Amit; Oomens, Cees W J; Schoonhoven, Lisette; Nixon, Jane

    2014-10-01

    To agree a draft pressure ulcer risk factor Minimum Data Set to underpin the development of a new evidenced-based Risk Assessment Framework. A recent systematic review identified the need for a pressure ulcer risk factor Minimum Data Set and development and validation of an evidenced-based pressure ulcer Risk Assessment Framework. This was undertaken through the Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056), funded by the National Institute for Health Research and incorporates five phases. This article reports phase two, a consensus study. Consensus study. A modified nominal group technique based on the Research and Development/University of California at Los Angeles appropriateness method. This incorporated an expert group, review of the evidence and the views of a Patient and Public Involvement service user group. Data were collected December 2010-December 2011. The risk factors and assessment items of the Minimum Data Set (including immobility, pressure ulcer and skin status, perfusion, diabetes, skin moisture, sensory perception and nutrition) were agreed. In addition, a draft Risk Assessment Framework incorporating all Minimum Data Set items was developed, comprising a two stage assessment process (screening and detailed full assessment) and decision pathways. The draft Risk Assessment Framework will undergo further design and pre-testing with clinical nurses to assess and improve its usability. It will then be evaluated in clinical practice to assess its validity and reliability. The Minimum Data Set could be used in future for large scale risk factor studies informing refinement of the Risk Assessment Framework. © 2014 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

  16. Modeling frictional melt injection to constrain coseismic physical conditions

    NASA Astrophysics Data System (ADS)

    Sawyer, William J.; Resor, Phillip G.

    2017-07-01

    Pseudotachylyte, a fault rock formed through coseismic frictional melting, provides an important record of coseismic mechanics. In particular, injection veins formed at a high angle to the fault surface have been used to estimate rupture directivity, velocity, pulse length, stress drop, as well as slip weakening distance and wall rock stiffness. These studies have generally treated injection vein formation as a purely elastic process and have assumed that processes of melt generation, transport, and solidification have little influence on the final vein geometry. Using a pressurized crack model, an analytical approximation of injection vein formation based on dike intrusion, we find that the timescales of quenching and flow propagation may be similar for a subset of injection veins compiled from the Asbestos Mountain Fault, USA, Gole Larghe Fault Zone, Italy, and the Fort Foster Brittle Zone, USA under minimum melt temperature conditions. 34% of the veins are found to be flow limited, with a final geometry that may reflect cooling of the vein before it reaches an elastic equilibrium with the wall rock. Formation of these veins is a dynamic process whose behavior is not fully captured by the analytical approach. To assess the applicability of simplifying assumptions of the pressurized crack we employ a time-dependent finite-element model of injection vein formation that couples elastic deformation of the wall rock with the fluid dynamics and heat transfer of the frictional melt. This finite element model reveals that two basic assumptions of the pressurized crack model, self-similar growth and a uniform pressure gradient, are false. The pressurized crack model thus underestimates flow propagation time by 2-3 orders of magnitude. Flow limiting may therefore occur under a wider range of conditions than previously thought. Flow-limited veins may be recognizable in the field where veins have tapered profiles or smaller aspect ratios than expected. The occurrence and shape of injection veins can be coupled with modeling to provide an independent estimate of minimum melt temperature. Finally, the large aspect ratio observed for all three populations of injection veins may be best explained by a large reduction in stiffness associated with coseismic damage, as injection vein growth is likely to far exceed the lifetime of dynamic stresses at any location along a fault.

  17. Modeling of drop breakup in the bag breakup regime

    NASA Astrophysics Data System (ADS)

    Wang, C.; Chang, S.; Wu, H.; Xu, J.

    2014-04-01

    Several analytic models for predicting the drop deformation and breakup have been developed over the last three decades, but modeling drop breakup in the bag-type regime is less reported. In this Letter, a breakup model has been proposed to predict the drop deformation length and breakup time in the bag-type breakup regime in a more accurate manner. In the present model, the drop deformation which is approximately as the displacement of the centre of mass (c. m.) along the axis located at the centre of the drop, and the movement of c. m. is obtained by solving the pressure balance equation. The effects of the drop deformation on the drop external aerodynamic force are considered in this model. Drop breakup occurs when the deformation length reaches the maximum value and the maximum deformation length is a function of Weber number. The performance and applicability of the proposed breakup model are tested against the published experimental data.

  18. 2D Simulations of Earthquake Cycles at a Subduction Zone Based on a Rate and State Friction Law -Effects of Pore Fluid Pressure Changes-

    NASA Astrophysics Data System (ADS)

    Mitsui, Y.; Hirahara, K.

    2006-12-01

    There have been a lot of studies that simulate large earthquakes occurring quasi-periodically at a subduction zone, based on the laboratory-derived rate-and-state friction law [eg. Kato and Hirasawa (1997), Hirose and Hirahara (2002)]. All of them assume that pore fluid pressure in the fault zone is constant. However, in the fault zone, pore fluid pressure changes suddenly, due to coseismic pore dilatation [Marone (1990)] and thermal pressurization [Mase and Smith (1987)]. If pore fluid pressure drops and effective normal stress rises, fault slip is decelerated. Inversely, if pore fluid pressure rises and effective normal stress drops, fault slip is accelerated. The effect of pore fluid may cause slow slip events and low-frequency tremor [Kodaira et al. (2004), Shelly et al. (2006)]. For a simple spring model, how pore dilatation affects slip instability was investigated [Segall and Rice (1995), Sleep (1995)]. When the rate of the slip becomes high, pore dilatation occurs and pore pressure drops, and the rate of the slip is restrained. Then the inflow of pore fluid recovers the pore pressure. We execute 2D earthquake cycle simulations at a subduction zone, taking into account such changes of pore fluid pressure following Segall and Rice (1995), in addition to the numerical scheme in Kato and Hirasawa (1997). We do not adopt hydrostatic pore pressure but excess pore pressure for initial condition, because upflow of dehydrated water seems to exist at a subduction zone. In our model, pore fluid is confined to the fault damage zone and flows along the plate interface. The smaller the flow rate is, the later pore pressure recovers. Since effective normal stress keeps larger, the fault slip is decelerated and stress drop becomes smaller. Therefore the smaller flow rate along the fault zone leads to the shorter earthquake recurrence time. Thus, not only the frictional parameters and the subduction rate but also the fault zone permeability affects the recurrence time of earthquake cycle. Further, the existence of heterogeneity in the permeability along the plate interface can bring about other slip behaviors, such as slow slip events. Our simulations indicate that, in addition to the frictional parameters, the permeability within the fault damage zone is one of essential parameters, which controls the whole earthquake cycle.

  19. Fuel thermal stability effects on spray characteristics

    NASA Technical Reports Server (NTRS)

    Lefebvre, A. H.; Nickolaus, D.

    1987-01-01

    The propensity of a heated hydrocarbon fuel toward solids deposition within a fuel injector is investigated experimentally. Fuel is arranged to flow through the injector at constant temperature, pressure, and flow rate and the pressure drop across the nozzle is monitored to provide an indication of the amount of deposition. After deposits have formed, the nozzle is removed from the test rig and its spray performance is compared with its performance before deposition. The spray characteristics measured include mean drop size, drop-size distribution, and radial and circumferential fuel distribution. It is found that small amounts of deposition can produce severe distortion of the fuel spray pattern. More extensive deposition restores spray uniformity, but the nozzle flow rate is seriously curtailed.

  20. An Assessment of Helium Evolution from Helium-Saturated Propellant Depressurization in Space

    NASA Technical Reports Server (NTRS)

    Nguyen, Bich N.; Best, Frederick; Wong, Tony; Kurwitz, Cable; McConnaughey, H. (Technical Monitor)

    2001-01-01

    Helium evolution from the transfer of helium-saturated propellant in space is quantified to assess its impacts from creating two-phase gas/liquid flow from the supply tank, gas injection into the receiving tank, and liquid discharge from the receiving tank. Propellant transfer takes place between two similar tanks whose maximum storage capacity is approximately 2.55 cubic meters each. The maximum on-orbit propellants transfer capability is 9000 lbm (fuel and oxidizer). The transfer line is approximately 1.27 cm in diameter and 6096 cm in length and comprised of the fluid interconnect system (FICS), the orbiter propellant transfer system (OPTS), and the International Space Station (ISS) propulsion module (ISSPM). The propellant transfer rate begins at approximately 11 liter per minute (lpm) and subsequently drops to approximately 0.5 lpm. The tank nominal operating pressure is approximately 1827 kPa (absolute). The line pressure drops for Monomethy1hydrazine (MMH) and Nitrogen tetroxide (NTO) at 11.3 lpm are approximately 202 kPa and 302 kPa, respectively. The pressure-drop results are based on a single-phase flow. The receiving tank is required to vent from approximately 1827 kPa to a lower pressure to affect propellant transfer. These pressure-drop scenarios cause the helium-saturated propellants to release excess helium. For tank ullage venting, the maximum volumes of helium evolved at tank pressure are approximately 0.5 ft3 for MMH and 2 ft3 for NTO. In microgravity environment, due to lack of body force, the helium evolution from a liquid body acts to propel it, which influences its fluid dynamics. For propellant transfer, the volume fractions of helium evolved at line pressure are 0.1% by volume for MMH and 0.6 % by volume for NTO at 11.3 lpm. The void fraction of helium evolved varies as an approximate second order power function of flow rate.

  1. Dynamics of diffusive bubble growth and pressure recovery in a bubbly rhyolitic melt embedded in an elastic solid

    USGS Publications Warehouse

    Chouet, Bernard A.; Dawson, Phillip B.; Nakano, Masaru

    2006-01-01

    We present a model of gas exsolution and bubble expansion in a melt supersaturated in response to a sudden pressure drop. In our model, the melt contains a suspension of gas bubbles of identical sizes and is encased in a penny-shaped crack embedded in an elastic solid. The suspension is modeled as a three-dimensional lattice of spherical cells with slight overlap, where each elementary cell consists of a gas bubble surrounded by a shell of volatile-rich melt. The melt is then subjected to a step drop in pressure, which induces gas exsolution and bubble expansion, resulting in the compression of the melt and volumetric expansion of the crack. The dynamics of diffusion-driven bubble growth and volumetric crack expansion span 9 decades in time. The model demonstrates that the speed of the crack response depends strongly on volatile diffusivity in the melt and bubble number density and is markedly sensitive to the ratio of crack thickness to crack radius and initial bubble radius but is relatively insensitive to melt viscosity. The net drop in gas concentration in the melt after pressure recovery represents only a small fraction of the initial concentration prior to the drop, suggesting the melt may undergo numerous pressure transients before becoming significantly depleted of gases. The magnitude of pressure and volume recovery in the crack depends sensitively on the size of the input-pressure transient, becoming relatively larger for smaller-size transients in a melt containing bubbles with initial radii less than 10-5 m. Amplification of the input transient may be large enough to disrupt the crack wall and induce brittle failure in the rock matrix surrounding the crack. Our results provide additional basis for the interpretation of volume changes in the magma conduit under Popocatépetl Volcano during Vulcanian degassing bursts in its eruptive activity in April–May 2000.

  2. Charged drop dynamics experiment using an electrostatic-acoustic hybrid system

    NASA Technical Reports Server (NTRS)

    Rhim, W. K.; Chung, S. K.; Trinh, E. H.; Elleman, D. D.

    1987-01-01

    The design and the performance of an electrostatic-acoustic hybrid system and its application to a charge drop rotation experiment are presented. This system can levitate a charged drop electrostatically and induce drop rotation or oscillation by imposing an acoustic torque or an oscillating acoustic pressure. Using this system, the equilibrium shapes and stability of a rotating charged drop were experimentally investigated. A 3 mm size water drop was rotated as a rigid body and its gyrostatic equilibrium shapes were observed. Families of axisymmetric shapes, two-lobed shapes, and eventual fissioning have been observed. With the assumption of 'effective surface tension' in which the surface charge simply modified the surface tension of neutral liquid, the results agree exceptionally well with the Brown and Scriven's (1980) prediction for uncharged drops.

  3. Star-shaped oscillations of Leidenfrost drops

    NASA Astrophysics Data System (ADS)

    Ma, Xiaolei; Liétor-Santos, Juan-José; Burton, Justin C.

    2017-03-01

    We experimentally investigate the self-sustained, star-shaped oscillations of Leidenfrost drops. The drops levitate on a cushion of evaporated vapor over a heated, curved surface. We observe modes with n =2 -13 lobes around the drop periphery. We find that the wavelength of the oscillations depends only on the capillary length of the liquid and is independent of the drop radius and substrate temperature. However, the number of observed modes depends sensitively on the liquid viscosity. The dominant frequency of pressure variations in the vapor layer is approximately twice the drop oscillation frequency, consistent with a parametric forcing mechanism. Our results show that the star-shaped oscillations are driven by capillary waves of a characteristic wavelength beneath the drop and that the waves are generated by a large shear stress at the liquid-vapor interface.

  4. Visualization and flow boiling heat transfer of hydrocarbons in a horizontal tube

    NASA Astrophysics Data System (ADS)

    Yang, Zhuqiang; Bi, Qincheng; Guo, Yong; Liu, Zhaohui; Yan, Jianguo

    2013-07-01

    Visualizations of a specific hydrocarbon fuel in a horizontal tube with 2.0 mm inside diameter were investigated. The experiments were conducted at mass velocity of 213.4, 426.5 and 640.2 kg/ (m2ṡs), diabatic lengths of 140, 240 and 420 mm under the pressure from 2.0-2.7 MPa. In the sub-pressure conditions, bubbly, intermittent, stratified-wave, churn and annular flow patterns were observed. The frictional pressure drops were also measured to distinguish the patterns. The development of flow patterns and frictional pressure drop were positively related to the mass velocity and the heat flux. However, the diabatic length of the tube takes an important part in the process. The residence time of the fluid does not only affect the transition of the patterns but influence the composition of the fuel manifested by the fuel color and carbon deposit. The special observational phenomenon was obtained for the supercritical pressure fluid. The flow in the tube became fuzzier and pressure drop changed sharply near the pseudocritical point. The flow boiling heat transfer characteristics of the hydrocarbons were also discussed respectively. The curve of critical heat flux about onset of nucleate boiling was plotted with different mass velocities and diabatic tube lengths. And heat transfer characteristics of supercritical fuel were proved to be better than that in subcritical conditions.

  5. Structural Affects on the Slamming Pressures of High-Speed Planing Craft

    NASA Astrophysics Data System (ADS)

    Ikeda, Christine; Taravella, Brandon; Judge, Carolyn

    2015-11-01

    High-speed planing craft are subjected to repeated slamming events in waves that can be very extreme depending on the wave topography, impact angle of the ship, forward speed of the ship, encounter angle, and height out of the water. The current work examines this fluid-structure interaction problem through the use of wedge drop experiments and a CFD code. In the first set of experiments, a rigid 20-degree deadrise angle wedge was dropped from a range of heights (0 <= H <= 0 . 6 m) and while pressures and accelerations of the slam even were measured. The second set of experiments involved a flexible-bottom 15-degree deadrise angle wedge that was dropped from from the same range of heights. In these second experiments, the pressures, accelerations, and strain field were measured. Both experiments are compared with a non-linear boundary value flat cylinder theory code in order to compare the pressure loading. The code assumes a rigid structure, therefore, the results between the code and the first experiment are in good agreement. The second experiment shows pressure magnitudes that are lower than the predictions due to the energy required to deform the structure. Funding from University of New Orleans Office of Research and Sponsored Programs and the Office of Naval Research.

  6. Single Channel Testing for Characterization of the Direct Gas Cooled Reactor and the SAFE-100 Heat Exchanger

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bragg-Sitton, S.M.; Propulsion Research Center, NASA Marshall Space Flight Center, Huntsville, AL 35812; Kapernick, R.

    2004-02-04

    Experiments have been designed to characterize the coolant gas flow in two space reactor concepts that are currently under investigation by NASA Marshall Space Flight Center and Los Alamos National Laboratory: the direct-drive gas-cooled reactor (DDG) and the SAFE-100 heatpipe-cooled reactor (HPR). For the DDG concept, initial tests have been completed to measure pressure drop versus flow rate for a prototypic core flow channel, with gas exiting to atmospheric pressure conditions. The experimental results of the completed DDG tests presented in this paper validate the predicted results to within a reasonable margin of error. These tests have resulted in amore » re-design of the flow annulus to reduce the pressure drop. Subsequent tests will be conducted with the re-designed flow channel and with the outlet pressure held at 150 psi (1 MPa). Design of a similar test for a nominal flow channel in the HPR heat exchanger (HPR-HX) has been completed and hardware is currently being assembled for testing this channel at 150 psi. When completed, these test programs will provide the data necessary to validate calculated flow performance for these reactor concepts (pressure drop and film temperature rise)« less

  7. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burkholder, Michael B.; Litster, Shawn, E-mail: litster@andrew.cmu.edu

    In this study, we analyze the stability of two-phase flow regimes and their transitions using chaotic and fractal statistics, and we report new measurements of dynamic two-phase pressure drop hysteresis that is related to flow regime stability and channel water content. Two-phase flow dynamics are relevant to a variety of real-world systems, and quantifying transient two-phase flow phenomena is important for efficient design. We recorded two-phase (air and water) pressure drops and flow images in a microchannel under both steady and transient conditions. Using Lyapunov exponents and Hurst exponents to characterize the steady-state pressure fluctuations, we develop a new, measurablemore » regime identification criteria based on the dynamic stability of the two-phase pressure signal. We also applied a new experimental technique by continuously cycling the air flow rate to study dynamic hysteresis in two-phase pressure drops, which is separate from steady-state hysteresis and can be used to understand two-phase flow development time scales. Using recorded images of the two-phase flow, we show that the capacitive dynamic hysteresis is related to channel water content and flow regime stability. The mixed-wettability microchannel and in-channel water introduction used in this study simulate a polymer electrolyte fuel cell cathode air flow channel.« less

  8. Feasibility of granular bed filtration of an aerosol of ultrafine metallic particles including a pressure drop regeneration system.

    PubMed

    Bémer, D; Wingert, L; Morele, Y; Subra, I

    2015-09-01

    A process for filtering an aerosol of ultrafine metallic particles (UFP) has been designed and tested, based on the principle of a multistage granular bed. The filtration system comprised a succession of granular beds of varying thickness composed of glass beads of different diameters. This system allows the pressure drop to be regenerated during filtration ("on-line" mode) using a vibrating probe. Tests monitoring the pressure drop were conducted on a "10-L/min" low airflow rate device and on a "100-m(3)/hr" prototype. Granular bed unclogging is automated on the latter. The cyclic operation and filtration performances are similar to that of filter medium-based industrial dust collectors. Filtration of ultrafine metallic particles generated by different industrial processes such as arc welding, metal cutting, or spraying constitutes a difficult problem due to the high filter clogging properties of these particles and to the high temperatures generally encountered. Granular beds represent an advantageous means of filtering these aerosols with difficult properties.

  9. Micro-structured heat exchanger for cryogenic mixed refrigerant cycles

    NASA Astrophysics Data System (ADS)

    Gomse, D.; Reiner, A.; Rabsch, G.; Gietzelt, T.; Brandner, J. J.; Grohmann, S.

    2017-12-01

    Mixed refrigerant cycles (MRCs) offer a cost- and energy-efficient cooling method for the temperature range between 80 and 200 K. The performance of MRCs is strongly influenced by entropy production in the main heat exchanger. High efficiencies thus require small temperature gradients among the fluid streams, as well as limited pressure drop and axial conduction. As temperature gradients scale with heat flux, large heat transfer areas are necessary. This is best achieved with micro-structured heat exchangers, where high volumetric heat transfer areas can be realized. The reliable design of MRC heat exchangers is challenging, since two-phase heat transfer and pressure drop in both fluid streams have to be considered simultaneously. Furthermore, only few data on the convective boiling and condensation kinetics of zeotropic mixtures is available in literature. This paper presents a micro-structured heat exchanger designed with a newly developed numerical model, followed by experimental results on the single-phase pressure drop and their implications on the hydraulic diameter.

  10. The effect of nanocrystalline cellulose on flow properties of fiber crop aqueous suspension.

    PubMed

    Gharehkhani, Samira; Seyed Shirazi, Seyed Farid; Yarmand, Hooman; Montazer, Elham; Kazi, Salim Newaz; Ibrahim, Rushdan; Ashjaei, Mehdi; Zulkifli, Nurin Wahidah Binti Mohd; Rahmati, Sadegh

    2018-03-15

    Nanocrystalline cellulose (NCC) a nature-based material, has gained significant attentions for its unique properties. The present study aims to investigate the flow behavior of cellulosic suspension containing non-wood pulp fibers and NCC, by means of rheological and pressure drop measurements. The NCC sample was prepared by sulfuric acid hydrolysis from Acacia mangium fibers. The rheological properties of kenaf/NCC suspensions were studied using viscosity and yield stress measurements. The pressure drop properties of the suspension flow were studied with respect to variation in flow velocity (0.4 m/s-3.6 m/s) and the NCC concentration (70 mg/l and 150 mg/l). The pressure drop results showed that the pulp suspension containing 150 mg/l NCC had higher drag reduction than kenaf suspension alone. The present insights into the flow of pulp/NCC suspension provide a new data and promote the application of NCC in industries. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Design study of an advanced gas generator. [which can be ignited during start-up period of turbine engines

    NASA Technical Reports Server (NTRS)

    Kim, S.; Trinh, H. P.

    1993-01-01

    A gas generator which can be ignited reliably during the initial start-up period and offers fairly uniform gas temperature at the exit was studied numerically. Various sizes and shapes of the mixing enhancement devices and their positions were examined to evaluate the uniformity of the exit gas temperature and the change of internal pressure drop incurred by introducing the mixing enhancement devices. By introducing a turbulence ring and a splash plate with an appropriate size and position, it was possible to obtain fairly uniform gas temperature distributions and a maximum gas temperature that is within the design limit temperature of 1600 R at the generator exit. However, with the geometry studied, the pressure drop across the generator was great, approximately 1150 psi, to satisfy the assigned design limit temperature. If the design limit temperature is increased to 1650 R, the pressure drop across the generator could be lowered by as much as 350 psi.

  12. Optimization of the Heat Exchangers of a Thermoelectric Generation System

    NASA Astrophysics Data System (ADS)

    Martínez, A.; Vián, J. G.; Astrain, D.; Rodríguez, A.; Berrio, I.

    2010-09-01

    The thermal resistances of the heat exchangers have a strong influence on the electric power produced by a thermoelectric generator. In this work, the heat exchangers of a thermoelectric generator have been optimized in order to maximize the electric power generated. This thermoelectric generator harnesses heat from the exhaust gas of a domestic gas boiler. Statistical design of experiments was used to assess the influence of five factors on both the electric power generated and the pressure drop in the chimney: height of the generator, number of modules per meter of generator height, length of the fins of the hot-side heat exchanger (HSHE), length of the gap between fins of the HSHE, and base thickness of the HSHE. The electric power has been calculated using a computational model, whereas Fluent computational fluid dynamics (CFD) has been used to obtain the thermal resistances of the heat exchangers and the pressure drop. Finally, the thermoelectric generator has been optimized, taking into account the restrictions on the pressure drop.

  13. Quantifying the influence of flow asymmetries on glottal sound sources in speech

    NASA Astrophysics Data System (ADS)

    Erath, Byron; Plesniak, Michael

    2008-11-01

    Human speech is made possible by the air flow interaction with the vocal folds. During phonation, asymmetries in the glottal flow field may arise from flow phenomena (e.g. the Coanda effect) as well as from pathological vocal fold motion (e.g. unilateral paralysis). In this study, the effects of flow asymmetries on glottal sound sources were investigated. Dynamically-programmable 7.5 times life-size vocal fold models with 2 degrees-of-freedom (linear and rotational) were constructed to provide a first-order approximation of vocal fold motion. Important parameters (Reynolds, Strouhal, and Euler numbers) were scaled to physiological values. Normal and abnormal vocal fold motions were synthesized, and the velocity field and instantaneous transglottal pressure drop were measured. Variability in the glottal jet trajectory necessitated sorting of the data according to the resulting flow configuration. The dipole sound source is related to the transglottal pressure drop via acoustic analogies. Variations in the transglottal pressure drop (and subsequently the dipole sound source) arising from flow asymmetries are discussed.

  14. Pressure drop and He II flow through fine mesh screens

    NASA Astrophysics Data System (ADS)

    Maddocks, J. R.; van Sciver, S. W.

    1989-05-01

    Fluid acquisition systems for He II transfer devices will utilize gallery arms to ensure that the fluid encounters the pump inlet. In near term experiments such as Superfluid Helium on Orbit Transfer (SHOOT), the preferred configuration consists of several rectangular channels which have one side made from a Dutch weave stainless steel screen having 325 x 2300 wires per inch. The effective pore diameter for this screen is about 5 microns. The present paper reports on measurements of pressure drop across a screen when it is subjected to a flow of liquid helium. The experiment measures the time rate of change of the level in two different helium reservoirs connected by a screen-blocked channel. Results with normal helium are compared with predictions based on the Armour-Cannon (1968) equations. The He II data show considerable deviation from the classical result. A discussion of the He II pressure drop results in terms of two fluid hydrodynamics is included.

  15. Condensation heat transfer and pressure drop of R-410A in flat aluminum multi-port tubes

    NASA Astrophysics Data System (ADS)

    Kim, Nae-Hyun

    2018-02-01

    Brazed heat exchangers with aluminum flat multi-port tubes are being used as condensers of residential air-conditioners. In this study, R-410A condensation tests were conducted in four multi-port tubes having a range of hydraulic diameter (0.78 ≤ Dh ≤ 0.95 mm). The test range covered the mass flux from 100 to 400 kg/m2 s and the heat flux at 3 kW/m2, which are typical operating conditions of residential air conditioners. Results showed that both the heat transfer coefficient and the pressure drop increased as the hydraulic diameter decreased. The effect of hydraulic diameter on condensation heat transfer was much larger than the predictions of existing correlations for the range of investigation. Comparison of the data with the correlations showed that some macro-channel tube correlations and mini-channel tube correlations reasonably predicted the heat transfer coefficient. However, macro-channel correlations highly overpredicted the pressure drop data.

  16. Effects of Swirler Shape on Two-Phase Swirling Flow in a Steam Separator

    NASA Astrophysics Data System (ADS)

    Kataoka, Hironobu; Shinkai, Yusuke; Tomiyama, Akio

    Experiments on two-phase swirling flow in a separator are carried out using several swirlers having different vane angles, different hub diameters and different number of vanes to seek a way for improving steam separators of uprated boiling water reactors. Ratios of the separated liquid flow rate to the total liquid flow rate, flow patterns, liquid film thicknesses and pressure drops are measured to examine the effects of swirler shape on air-water two-phase swirling annular flows in a one-fifth scale model of the separator. As a result, the following conclusions are obtained for the tested swirlers: (1) swirler shape scarcely affects the pressure drop in the barrel of the separator, (2) decreasing the vane angle is an effective way for reducing the pressure drop in the diffuser of the separator, and (3) the film thickness at the inlet of the pick-off-ring of the separator is not sensitive to swirler shape, which explains the reason why the separator performance does not depend on swirler shape.

  17. Characteristics of Evaporator with a Lipuid-Vapor Separator

    NASA Astrophysics Data System (ADS)

    Ikeguchi, Masaki; Tanaka, Naoki; Yumikura, Tsuneo

    Flow pattern of refrigerant in a heat exchanger tube changes depending on vapor quality, tube diameter, refrigerant flow rate and refrigerant properties. High flow rate causes mist flow where the quality is from 0.8 to 1.0. 1n this flow pattern, the liquid film detaches from the tube wall so that the heat flow is intervened. The heat transfer coefficient generally increases with the flow rate. But the pressure drop of refrigerant flow simultaneously increases and the region of the mist flow enlarges. In order to reduce the pressure drop and suppress the mist flow, we have developped a small liquid-vapor separator that removes the vapor from the evaporating refrigerant flow. This separator is equipped in the middle of the evaporator where the flow pattern is annular. The experiments to evaluate the effect of this separator were carried out and the following conclutions were obtained. (1) Average heat transfer coefficient increases by 30-60 %. (2) Pressure drop reduces by 20-30 %. (3) Cooling Capacity increases by 2-9 %.

  18. Bubble and Slug Flow at Microgravity Conditions: State of Knowledge and Open Questions

    NASA Technical Reports Server (NTRS)

    Colin, C.; Fabre, J.; McQuillen, J.

    1996-01-01

    Based on the experiments carried out over the past decade at microgravity conditions, an overview of our current knowledge of bubbly and slug flows is presented. The transition from bubble to slug flow, the void fraction and the pressure drop are discussed from the data collected in the literature. The transition from bubble to slug flow may be predicted by introducing a critical void fraction that depends on the fluid properties and the pipe diameter; however, the role of coalescence which controls this transition is not clearly understood. The void fraction may be accurately calculated using a drift-flux model. It is shown from local measurements that the drift of the gas with respect to the mixture is due to non-uniform radial distribution of void fraction. The pressure drop happens to be controlled by the liquid flow for bubbly flow whereas for slug flow the experimental results show that pressure drops is larger than expected. From this study, the guidelines for future research in microgravity are given.

  19. Design and performance prediction of solar adsorption cooling for mobile vaccine refrigerator

    NASA Astrophysics Data System (ADS)

    Djubaedah, Euis; Taufan, Andi; Ratnasari, Nadhira; Fahrizal, Adjie; Hamidi, Qayyum; Nasruddin

    2017-03-01

    Adsorption cooling is a process that uses a drop-in pressure caused by the adsorption of adsorbate by adsorbent. Adsorption process creates a pressure drop which can bring down the temperature to the intended condition. This approach can be used in vaccine transportation as the vaccines need to be stored at low temperatures (2°C to 8°C for preserving vaccines). The pressure decrease can be obtained by adsorption water in zeolites and can also produce the temperature drop in the main chamber. The adsorption process of water will decrease until reaching saturation condition. Heat is needed to keep the system continuous as it starts a desorption process. From the simulation using MATLAB, it is found that the mobile vaccine refrigerator can reach the temperature of 2°C in 180 seconds with the amount of cooling power generated is up to 1530 W. The insulation can hold the allowable temperature range inside the vaccine cabin for 15.6795 hours.

  20. Pressure drop and He II flow through fine mesh screens

    NASA Technical Reports Server (NTRS)

    Maddocks, J. R.; Van Sciver, S. W.

    1989-01-01

    Fluid acquisition systems for He II transfer devices will utilize gallery arms to ensure that the fluid encounters the pump inlet. In near term experiments such as Superfluid Helium on Orbit Transfer (SHOOT), the preferred configuration consists of several rectangular channels which have one side made from a Dutch weave stainless steel screen having 325 x 2300 wires per inch. The effective pore diameter for this screen is about 5 microns. The present paper reports on measurements of pressure drop across a screen when it is subjected to a flow of liquid helium. The experiment measures the time rate of change of the level in two different helium reservoirs connected by a screen-blocked channel. Results with normal helium are compared with predictions based on the Armour-Cannon (1968) equations. The He II data show considerable deviation from the classical result. A discussion of the He II pressure drop results in terms of two fluid hydrodynamics is included.

  1. Air Flow and Pressure Drop Measurements Across Porous Oxides

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.; Cuy, Michael D.; Werner, Roger A.

    2008-01-01

    This report summarizes the results of air flow tests across eight porous, open cell ceramic oxide samples. During ceramic specimen processing, the porosity was formed using the sacrificial template technique, with two different sizes of polystyrene beads used for the template. The samples were initially supplied with thicknesses ranging from 0.14 to 0.20 in. (0.35 to 0.50 cm) and nonuniform backside morphology (some areas dense, some porous). Samples were therefore ground to a thickness of 0.12 to 0.14 in. (0.30 to 0.35 cm) using dry 120 grit SiC paper. Pressure drop versus air flow is reported. Comparisons of samples with thickness variations are made, as are pressure drop estimates. As the density of the ceramic material increases the maximum corrected flow decreases rapidly. Future sample sets should be supplied with samples of similar thickness and having uniform surface morphology. This would allow a more consistent determination of air flow versus processing parameters and the resulting porosity size and distribution.

  2. Airfoil profiles for minimum pressure drag at supersonic velocities -- general analysis with application to linearized supersonic flow

    NASA Technical Reports Server (NTRS)

    Chapman, Dean R

    1952-01-01

    A theoretical investigation is made of the airfoil profile for minimum pressure drag at zero lift in supersonic flow. In the first part of the report a general method is developed for calculating the profile having the least pressure drag for a given auxiliary condition, such as a given structural requirement or a given thickness ratio. The various structural requirements considered include bending strength, bending stiffness, torsional strength, and torsional stiffness. No assumption is made regarding the trailing-edge thickness; the optimum value is determined in the calculations as a function of the base pressure. To illustrate the general method, the optimum airfoil, defined as the airfoil having minimum pressure drag for a given auxiliary condition, is calculated in a second part of the report using the equations of linearized supersonic flow.

  3. Numerical Simulation of Flow and Heat Transfer Characteristic of 4k Regenerators at High Frequency

    NASA Astrophysics Data System (ADS)

    Li, Zhuopei; Jiang, Yanlong; Gan, Zhihua; Qiu, Limin

    Regenerator is a key component for all regenerative cryocoolers. 4K regenerative cryocoolers can be applied to provide cooling for low temperature superconductors, space and military infrared detectors, and medical examination etc. Stirling type pulse tube cryocoolers (SPTC), one type of regenerative cryocoolers, operate at high frequencies. As a result, SPTCs have the advantage of compact structure and low weight compared with G-M type pulse tube cryocoolers operating at low frequencies. However, as the frequency increase the thermal penetration depth of helium gas in the regenerator is greatly reduced which makes the heat transfer between the gas and the regenerator worse. In order to improve the heat transfer efficiency, regenerator materials with smaller hydraulic diameters are used. Therefore the flow resistance between the gas and the regenerator material will increase leading to larger pressure drop from the hot end to the cold end of the regenerator. The cooling performance is deteriorated due to the decreased pressure ratio (maximum pressure divided by minimum pressure) at the cold end. Also, behavior of helium at 4K deviates remarkably from that of ideal gas which has a significant influence both the flow and heat transfer characteristic within a regenerator. In this paper numerical simulation on the behavior of a 4K regenerator at high frequency is carried out to provide guidance for the optimization of the flow and heat transfer performance within a regenerator. Thermodynamic analysis of effect of the non-ideal gas behavior of helium at 4K on 4K regenerator at high frequency is investigated.

  4. Validation of an All-Pressure Fluid Drop Model: Heptane Fluid Drops in Nitrogen

    NASA Technical Reports Server (NTRS)

    Harstad, K.; Bellan, J.; Bulzan, Daniel L. (Technical Monitor)

    2000-01-01

    Despite the fact that supercritical fluids occur both in nature and in industrial situations, the fundamentals of their behavior is poorly understood because supercritical fluids combine the characteristics of both liquids and gases, and therefore their behavior is not intuitive. There are several specific reasons for the lack of understanding: First, data from (mostly optical) measurements can be very misleading because regions of high density thus observed are frequently identified with liquids. A common misconception is that if in an experiment one can optically identify "drops" and "ligaments", the observed fluid must be in a liquid state. This inference is incorrect because in fact optical measurements detect any large change (i.e. gradients) in density. Thus, the density ratio may be well below Omicron(10(exp 3)) that characterizes its liquid/gas value, but the measurement will still identify a change in the index of refraction providing that the change is sudden (steep gradients). As shown by simulations of supercritical fluids, under certain conditions the density gradients may remain large during the supercritical binary fluids mixing, thus making them optically identifiable. Therefore, there is no inconsistency between the optical observation of high density regions and the fluids being in a supercritical state. A second misconception is that because a fluid has a liquid-like density, it is appropriate to model it as a liquid. However, such fluids may have liquid-like densities while their transport properties differ from those of a liquid. Considering that the critical pressure of most fuel hydrocarbons used in Diesel and gas turbine engines is in the range of 1.5 - 3 MPa, and the fact that the maximum pressure attained in these engines is about 6 Mps, it is clear that the fuel in the combustion chamber will experience both subcritical and supercritical conditions. Studies of drop behavior over a wide range of pressures were performed in the past, however none of these studies identified the crucial differences between the subcritical and supercritical behavior. In fact, in two of these studies, it was found that the subcritical and supercritical behavior is similar as the drop diameter decreased according to the classical d(exp 2)-law over a wide range of pressures and drop diameters. The present study is devoted to the exploration of differences in fluid-behavior characteristics under subcritical and supercritical conditions in the particular case of heptane fluid drops in nitrogen; these substances were selected because of the availability of experimental observations for model validation.

  5. Effect of drop volume and surface statistics on the superhydrophobicity of randomly rough substrates

    NASA Astrophysics Data System (ADS)

    Afferrante, L.; Carbone, G.

    2018-01-01

    In this paper, a simple theoretical approach is developed with the aim of evaluating shape, interfacial pressure, apparent contact angle and contact area of liquid drops gently deposed on randomly rough surfaces. This method can be useful to characterize the superhydrophobic properties of rough substrates, and to investigate the contact behavior of impacting drops. We assume that (i) the size of the apparent liquid-solid contact area is much larger than the micromorphology of the substrate, and (ii) a composite interface is always formed at the microscale. Results show apparent contact angle and liquid-solid area fraction are slightly influenced by the drop volume only at relatively high values of the root mean square roughness h rms, whereas the effect of volume is practically negligible at small h rms. The main statistical quantity affecting the superhydrophobic properties is found to be the Wenzel roughness parameter r W, which depends on the average slope of the surface heights. Moreover, transition from the Cassie-Baxter state to the Wenzel one is observed when r W reduces below a certain critical value, and theoretical predictions are found to be in good agreement with experimental data. Finally, the present method can be conveniently exploited to evaluate the occurrence of pinning phenomena in the case of impacting drops, as the Wenzel critical pressure for liquid penetration gives an estimation of the maximum impact pressure tolerated by the surface without pinning occurring.

  6. Temporal modulation transfer functions in auditory receptor fibres of the locust ( Locusta migratoria L.).

    PubMed

    Prinz, P; Ronacher, B

    2002-08-01

    The temporal resolution of auditory receptors of locusts was investigated by applying noise stimuli with sinusoidal amplitude modulations and by computing temporal modulation transfer functions. These transfer functions showed mostly bandpass characteristics, which are rarely found in other species at the level of receptors. From the upper cut-off frequencies of the modulation transfer functions the minimum integration times were calculated. Minimum integration times showed no significant correlation to the receptor spike rates but depended strongly on the body temperature. At 20 degrees C the average minimum integration time was 1.7 ms, dropping to 0.95 ms at 30 degrees C. The values found in this study correspond well to the range of minimum integration times found in birds and mammals. Gap detection is another standard paradigm to investigate temporal resolution. In locusts and other grasshoppers application of this paradigm yielded values of the minimum detectable gap widths that are approximately twice as large than the minimum integration times reported here.

  7. Active cooling-based surface confinement system for thermal soil treatment

    DOEpatents

    Aines, R.D.; Newmark, R.L.

    1997-10-28

    A thermal barrier is disclosed for surface confinement with active cooling to control subsurface pressures during thermal remediation of shallow (5-20 feet) underground contaminants. If steam injection is used for underground heating, the actively cooled thermal barrier allows the steam to be injected into soil at pressures much higher (20-60 psi) than the confining strength of the soil, while preventing steam breakthrough. The rising steam is condensed to liquid water at the thermal barrier-ground surface interface. The rapid temperature drop forced by the thermal barrier drops the subsurface pressure to below atmospheric pressure. The steam and contaminant vapors are contained by the thermal blanket, which can be made of a variety of materials such as steel plates, concrete slabs, membranes, fabric bags, or rubber bladders. 1 fig.

  8. Active cooling-based surface confinement system for thermal soil treatment

    DOEpatents

    Aines, Roger D.; Newmark, Robin L.

    1997-01-01

    A thermal barrier is disclosed for surface confinement with active cooling to control subsurface pressures during thermal remediation of shallow (5-20 feet) underground contaminants. If steam injection is used for underground heating, the actively cooled thermal barrier allows the steam to be injected into soil at pressures much higher (20-60 psi) than the confining strength of the soil, while preventing steam breakthrough. The rising steam is condensed to liquid water at the thermal barrier-ground surface interface. The rapid temperature drop forced by the thermal barrier drops the subsurface pressure to below atmospheric pressure. The steam and contaminant vapors are contained by the thermal blanket, which can be made of a variety of materials such as steel plates, concrete slabs, membranes, fabric bags, or rubber bladders.

  9. Contact Line Instability Caused by Air Rim Formation under Nonsplashing Droplets.

    PubMed

    Pack, Min; Kaneelil, Paul; Kim, Hyoungsoo; Sun, Ying

    2018-05-01

    Drop impact is fundamental to various natural and industrial processes such as rain-induced soil erosion and spray-coating technologies. The recent discovery of the role of air entrainment between the droplet and the impacting surface has produced numerous works, uncovering the unique physics that correlates the air film dynamics with the drop impact outcomes. In this study, we focus on the post-failure air entrainment dynamics for We numbers well below the splash threshold under different ambient pressures and elucidate the interfacial instabilities formed by air entrainment at the wetting front of impacting droplets on perfectly smooth, viscous films of constant thickness. A high-speed total internal reflection microscopy technique accounting for the Fresnel reflection at the drop-air interface allows for in situ measurements of an entrained air rim at the wetting front. The presence of an air rim is found to be a prerequisite to the interfacial instability which is formed when the capillary pressure in the vicinity of the contact line can no longer balance the increasing gas pressure near the wetting front. A critical capillary number for the air rim formation is experimentally identified above which the wetting front becomes unstable where this critical capillary number inversely scales with the ambient pressure. The contact line instabilities at relatively low We numbers ( We ∼ O(10)) observed in this study provide insight into the conventional understanding of hydrodynamic instabilities under drop impact which usually require We ≫ 10.

  10. Experimental analysis for heat transfer of nanofluid with wire coil turbulators in a concentric tube heat exchanger

    NASA Astrophysics Data System (ADS)

    Akyürek, Eda Feyza; Geliş, Kadir; Şahin, Bayram; Manay, Eyüphan

    2018-06-01

    Nanofluids are a novel class of heat transfer suspensions of metallic or nonmetallic nanopowders with a size of less than 100 nm in base fluids and they can increase heat transfer potential of the base fluids in various applications. In the last decade, nanofluids have become an intensive research topic because of their improved thermal properties and possible heat transfer applications. For comparison, an experiment using water as the working fluid in the heat exchanger without wire coils was also performed. Turbulent forced convection heat transfer and pressure drop characteristics of Al2O3-water nanofluids in a concentric tube heat exchanger with and without wire coil turbulators were experimentally investigated in this research. Experiments effected particle volume concentrations of 0.4-0.8 to 1.2-1.6 vol% in the Reynolds number range from 4000 to 20,000. Two turbulators with the pitches of 25 mm and 39 mm were used. The average Nusselt number increased with increasing the Reynolds number and particle concentrations. Moreover, the pressure drop of the Al2O3-water nanofluid showed nearly equal to that of pure water at the same Reynolds number range. As a result, nanofluids with lower particle concentrations did not show an important influence on pressure drop change. Nonetheless, when the wire coils used in the heat exchanger, it increased pressure drop as well as the heat transfer coefficient.

  11. Is MRI-based CFD able to improve clinical treatment of coarctations of aorta?

    PubMed

    Goubergrits, L; Riesenkampff, E; Yevtushenko, P; Schaller, J; Kertzscher, U; Berger, F; Kuehne, T

    2015-01-01

    Pressure drop associated with coarctation of the aorta (CoA) can be successfully treated surgically or by stent placement. However, a decreased life expectancy associated with altered aortic hemodynamics was found in long-term studies. Image-based computational fluid dynamics (CFD) is intended to support particular diagnoses, to help in choosing between treatment options, and to improve performance of treatment procedures. This study aimed to prove the ability of CFD to improve aortic hemodynamics in CoA patients. In 13 patients (6 males, 7 females; mean age 25 ± 14 years), we compared pre- and post-treatment peak systole hemodynamics [pressure drops and wall shear stress (WSS)] vs. virtual treatment as proposed by biomedical engineers. Anatomy and flow data for CFD were based on MRI and angiography. Segmentation, geometry reconstruction and virtual treatment geometry were performed using the software ZIBAmira, whereas peak systole flow conditions were simulated with the software ANSYS(®) Fluent(®). Virtual treatment significantly reduced pressure drop compared to post-treatment values by a mean of 2.8 ± 3.15 mmHg, which significantly reduced mean WSS by 3.8 Pa. Thus, CFD has the potential to improve post-treatment hemodynamics associated with poor long-term prognosis of patients with coarctation of the aorta. MRI-based CFD has a huge potential to allow the slight reduction of post-treatment pressure drop, which causes significant improvement (reduction) of the WSS at the stenosis segment.

  12. Sampling methods, dispersion patterns, and fixed precision sequential sampling plans for western flower thrips (Thysanoptera: Thripidae) and cotton fleahoppers (Hemiptera: Miridae) in cotton.

    PubMed

    Parajulee, M N; Shrestha, R B; Leser, J F

    2006-04-01

    A 2-yr field study was conducted to examine the effectiveness of two sampling methods (visual and plant washing techniques) for western flower thrips, Frankliniella occidentalis (Pergande), and five sampling methods (visual, beat bucket, drop cloth, sweep net, and vacuum) for cotton fleahopper, Pseudatomoscelis seriatus (Reuter), in Texas cotton, Gossypium hirsutum (L.), and to develop sequential sampling plans for each pest. The plant washing technique gave similar results to the visual method in detecting adult thrips, but the washing technique detected significantly higher number of thrips larvae compared with the visual sampling. Visual sampling detected the highest number of fleahoppers followed by beat bucket, drop cloth, vacuum, and sweep net sampling, with no significant difference in catch efficiency between vacuum and sweep net methods. However, based on fixed precision cost reliability, the sweep net sampling was the most cost-effective method followed by vacuum, beat bucket, drop cloth, and visual sampling. Taylor's Power Law analysis revealed that the field dispersion patterns of both thrips and fleahoppers were aggregated throughout the crop growing season. For thrips management decision based on visual sampling (0.25 precision), 15 plants were estimated to be the minimum sample size when the estimated population density was one thrips per plant, whereas the minimum sample size was nine plants when thrips density approached 10 thrips per plant. The minimum visual sample size for cotton fleahoppers was 16 plants when the density was one fleahopper per plant, but the sample size decreased rapidly with an increase in fleahopper density, requiring only four plants to be sampled when the density was 10 fleahoppers per plant. Sequential sampling plans were developed and validated with independent data for both thrips and cotton fleahoppers.

  13. Conceptual design for a laminar-flying-wing aircraft

    NASA Astrophysics Data System (ADS)

    Saeed, T. I.

    The laminar-flying-wing aircraft appears to be an attractive long-term prospect for reducing the environmental impact of commercial aviation. In assessing its potential, a relatively straightforward initial step is the conceptual design of a version with restricted sweep angle. Such a design is the topic of this thesis. Subject to constraints, this research aims to; provide insight into the parameters affecting practical laminar-flow-control suction power requirements; identify a viable basic design specification; and, on the basis of this, an assessment of the fuel efficiency through a detailed conceptual design study. It is shown that there is a minimum power requirement independent of the suction system design, associated with the stagnation pressure loss in the boundary layer. This requirement increases with aerofoil section thickness, but depends only weakly on Mach number and (for a thick, lightly-loaded laminar flying wing) lift coefficient. Deviation from the optimal suction distribution, due to a practical chamber-based architecture, is found to have very little effect on the overall suction coefficient. In the spanwise direction, through suitable choice of chamber depth, the pressure drop due to frictional and inertial effects may be rendered negligible. Finally, it is found that the pressure drop from the aerofoil surface to the pump collector ducts determines the power penalty. To identify the viable basic design specification, a high-level exploration of the laminar flying wing design space is performed. The characteristics of the design are assessed as a function of three parameters: thickness-to-chord ratio, wingspan, and unit Reynolds number. A feasible specification, with 20% thickness-to-chord, 80 m span and a unit Reynolds number of 8 x 106 m-1, is identified; it corresponds to a 187 tonne aircraft which cruises at Mach 0.67 and altitude 22,500 ft, with lift coefficient 0.14. On the basis of this specification, a detailed conceptual design is undertaken. A 220-passenger laminar-flying-wing concept, propelled by three turboprop engines, with a cruise range of 9000 km is developed. The laminar flying wing proposed in this thesis falls short of the performance improvements expected of the concept, and is not worth the development effort.

  14. A Rocket Engine Design Expert System

    NASA Technical Reports Server (NTRS)

    Davidian, Kenneth J.

    1989-01-01

    The overall structure and capabilities of an expert system designed to evaluate rocket engine performance are described. The expert system incorporates a JANNAF standard reference computer code to determine rocket engine performance and a state of the art finite element computer code to calculate the interactions between propellant injection, energy release in the combustion chamber, and regenerative cooling heat transfer. Rule-of-thumb heuristics were incorporated for the H2-O2 coaxial injector design, including a minimum gap size constraint on the total number of injector elements. One dimensional equilibrium chemistry was used in the energy release analysis of the combustion chamber. A 3-D conduction and/or 1-D advection analysis is used to predict heat transfer and coolant channel wall temperature distributions, in addition to coolant temperature and pressure drop. Inputting values to describe the geometry and state properties of the entire system is done directly from the computer keyboard. Graphical display of all output results from the computer code analyses is facilitated by menu selection of up to five dependent variables per plot.

  15. A rocket engine design expert system

    NASA Technical Reports Server (NTRS)

    Davidian, Kenneth J.

    1989-01-01

    The overall structure and capabilities of an expert system designed to evaluate rocket engine performance are described. The expert system incorporates a JANNAF standard reference computer code to determine rocket engine performance and a state-of-the-art finite element computer code to calculate the interactions between propellant injection, energy release in the combustion chamber, and regenerative cooling heat transfer. Rule-of-thumb heuristics were incorporated for the hydrogen-oxygen coaxial injector design, including a minimum gap size constraint on the total number of injector elements. One-dimensional equilibrium chemistry was employed in the energy release analysis of the combustion chamber and three-dimensional finite-difference analysis of the regenerative cooling channels was used to calculate the pressure drop along the channels and the coolant temperature as it exits the coolant circuit. Inputting values to describe the geometry and state properties of the entire system is done directly from the computer keyboard. Graphical display of all output results from the computer code analyses is facilitated by menu selection of up to five dependent variables per plot.

  16. NASA Tech Briefs, April 2004

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Topics covered include: Analysis of SSEM Sensor Data Using BEAM; Hairlike Percutaneous Photochemical Sensors; Video Guidance Sensors Using Remotely Activated Targets; Simulating Remote Sensing Systems; EHW Approach to Temperature Compensation of Electronics; Polymorphic Electronic Circuits; Micro-Tubular Fuel Cells; Whispering-Gallery-Mode Tunable Narrow-Band-Pass Filter; PVM Wrapper; Simulation of Hyperspectral Images; Algorithm for Controlling a Centrifugal Compressor; Hybrid Inflatable Pressure Vessel; Double-Acting, Locking Carabiners; Position Sensor Integral with a Linear Actuator; Improved Electromagnetic Brake; Flow Straightener for a Rotating-Drum Liquid Separator; Sensory-Feedback Exoskeletal Arm Controller; Active Suppression of Instabilities in Engine Combustors; Fabrication of Robust, Flat, Thinned, UV-Imaging CCDs; Chemical Thinning Process for Fabricating UV-Imaging CCDs; Pseudoslit Spectrometer; Waste-Heat-Driven Cooling Using Complex Compound Sorbents; Improved Refractometer for Measuring Temperatures of Drops; Semiconductor Lasers Containing Quantum Wells in Junctions; Phytoplankton-Fluorescence-Lifetime Vertical Profiler; Hexagonal Pixels and Indexing Scheme for Binary Images; Finding Minimum-Power Broadcast Trees for Wireless Networks; and Automation of Design Engineering Processes.

  17. Influence of long-time stress relief treatments on the dynamic fracture toughness properties of ASME SA508 C1 2a and ASME SA533 GR B C12 pressure vessel steels

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Logsdon, W.A.

    1982-03-01

    Dynamic fracture toughness tests were performed on materials which had been subjected to one of three long-time post weld type stress relief heat treatments: 48 hours at 1000/degree/F (538/degree/C), 24 hours at 1125/degree/F (607/degree/C), and 48 hours at 1125/degree/F (607/degree/C). Linear elastic K/sub Id/ results were obtained at low temperatures while J-integral techniques were utilized to evaluate dynamic fracture toughness over the transition and upper shelf temperature ranges. Tensile, Charpy impact, and drop weight nil-ductility transition tests as well as room temperature, air environment fatigue crack growth rate tests (SA508 Cl 2a only) were also performed. The fracture toughness ofmore » both materials exceeded the ASME specified minimum reference toughness K/sub IR/ curve. 17 refs.« less

  18. Coalescence of viscous drops translating through a capillary tube

    NASA Astrophysics Data System (ADS)

    AlMatroushi, Eisa; Borhan, Ali

    2014-03-01

    An experimental study of the interaction and coalescence of viscous drops moving through a cylindrical capillary tube under low Reynolds number conditions is presented. The combined pressure- and buoyancy-driven motion of drops in a Newtonian continuous phase is examined. The interaction between two drops is quantified using image analysis, and measurements of the coalescence time are reported for various drop size ratios, Bond numbers, and viscosity ratios. The time scale for coalescence in the non-axisymmetric configuration is found to be substantially larger than that for coalescence in the axisymmetric configuration. Measurements of the radius of the liquid film formed between the two drops at the instant of apparent contact are used in conjunction with a planar film drainage model to predict the dependence of the coalescence time on drop size ratio for coalescence of low viscosity-ratio drops in the axisymmetric configuration.

  19. Generation and characterization of surface layers on acoustically levitated drops.

    PubMed

    Tuckermann, Rudolf; Bauerecker, Sigurd; Cammenga, Heiko K

    2007-06-15

    Surface layers of natural and technical amphiphiles, e.g., octadecanol, stearic acid and related compounds as well as perfluorinated fatty alcohols (PFA), have been investigated on the surface of acoustically levitated drops. In contrast to Langmuir troughs, traditionally used in the research of surface layers at the air-water interface, acoustic levitation offers the advantages of a minimized and contact-less technique. Although the film pressure cannot be directly adjusted on acoustically levitated drops, it runs through a wide pressure range due to the shrinking surface of an evaporating drop. During this process, different states of the generated surface layer have been identified, in particular the phase transition from the gaseous or liquid-expanded to the liquid-condensed state of surface layers of octadecanol and other related amphiphiles. Characteristic parameters, such as the relative permeation resistance and the area per molecule in a condensed surface layer, have been quantified and were found comparable to results obtained from surface layers generated on Langmuir troughs.

  20. Structure and characteristics of heterogeneous detonation

    NASA Astrophysics Data System (ADS)

    Nicholls, J. A.; Sichel, M.; Kauffman, C. W.

    1983-09-01

    The emphasis of this research program centered around the structure of heterogeneous detonation waves, inasmuch as this had been found to be very important to the detonation characteristics of heterogeneous mixtures. On the experimental side, a vertical detonation tube was used wherein liquid fuel drops, all of one size, were generated at the top of the tube and allowed to fall vertically into the desired gaseous mixture. A strong blast wave was transmitted into the mixture through use of an auxiliary shock tube. The propagation of the resultant wave was monitored by pressure switches, pressure transducers, and photography. The low vapor pressure liquid fuel, decane (400 micrometer drop size) was used for most of the experiments. Attention was given to wave structure, wave velocity, and initiation energy. Three atmospheres (100% O2; 40% O2/60% N2; and air) and a number of equivalence ratios were investigated. Holographic pictures and streak photography were employed to study the drop shattering process and the structure of the front. Other experiments investigated the addition of the sensitizer, normal propyl nitrate (NPN), to the decane. The important aspect of vapor pressure was studied by heating the entire tube to various elevated temperatures and then noting the effect on detonability.

  1. Preliminary endurance tests of water vaporizers for resistojet applications

    NASA Technical Reports Server (NTRS)

    Morren, W. Earl; Macrae, Gregory S.

    1993-01-01

    Three water vaporizers designed for resistojet applications were built and tested for periods up to 500 h and 250 thermal cycles. Two of the vaporizers were not sensitive to orientation with respect to gravity, an indication of likely compatibility with low-gravity environments. Some temperatures and pressures in the third were impacted by orientation, although operation was always stable. The pressure drop across the sand-filled version increased by 147 percent in 38 h and 19 thermal cycles. Bonding of the sand granules in the downstream end of the heat exchanger was the suspected cause of failure of this vaporizer. Pressure drops across the two sintered stainless steel-filled versions were more gradual. One, with a pore size of 60 microns, showed an 80 percent increase in 500 h and 250 thermal cycles and another, with a 10 microns poresize, showed a 29 percent increase in 350 h and 175 thermal cycles. Testing of the latter metal-filled vaporizer was ongoing as of this writing. Oxidation of the porous metal packing materials in these vaporizers, with subsequent deposition of oxide particles within the pores, was believed to have caused the observed increases in pressure drops.

  2. Role of vortices in growth of microbubbles at mitral mechanical heart valve closure.

    PubMed

    Rambod, Edmond; Beizai, Masoud; Sahn, David J; Gharib, Morteza

    2007-07-01

    This study is aimed at refining our understanding of the role of vortex formation at mitral mechanical heart valve (MHV) closure and its association with the high intensity transient signals (HITS) seen in echocardiographic studies with MHV recipients. Previously reported numerical results described a twofold process leading to formation of gas-filled microbubbles in-vitro: (1) nucleation and (2) growth of micron size bubbles. The growth itself consists of two processes: (a) diffusion and (b) sudden pressure drop due to valve closure. The role of diffusion has already been shown to govern the initial growth of nuclei. Pressure drop at mitral MHV closure may be attributed to other phenomena such as squeezed flow, water hammer and primarily, vortex cavitation. Mathematical analysis of vortex formation at mitral MHV closure revealed that a closing velocity of approximately 12 m/s can induce a strong regurgitant vortex which in return can instigate a local pressure drop of about 0.9 atm. A 2D experimental model of regurgitant flows was used to substantiate the impact of vortices. At simulated flow and pressure conditions, a regurgitant vortex was observed to drastically enlarge micron size hydrogen bubbles at its core.

  3. Phoenix Mars Lander: Vortices and Dust Devils at the Landing Site

    NASA Astrophysics Data System (ADS)

    Ellehoj, M. D.; Taylor, P. A.; Gunnlaugsson, H. P.; Gheynani, B. T.; Drube, L.; von Holstein-Rathlou, C.; Whiteway, J.; Lemmon, M.; Madsen, M. B.; Fisher, D.; Volpe, R.; Smith, P.

    2008-12-01

    Near continuous measurements of temperatures and pressure on the Phoenix Mars Lander are used to identify the passage of vertically oriented vortex structures at the Phoenix landing site (126W, 68N) on Mars. Observations: During the Phoenix mission the pressure and temperature sensors frequently detected features passing over or close to the lander. Short duration (order 20 s) pressure drops of order 1-2 Pa, and often less, were observed relatively frequently, accompanied by increases in temperature. Similar features were observed from the Pathfinder mission, although in that case the reported pressure drops were often larger [1]. Statistics of the pressure drop features over the first 102 sols of the Phoenix mission shows that most of the events occur between noon and 15:00 LMST - the hottest part of the sol. Dust Raising: By assuming the concept of a vortex in cyclostrophic flow as well as various assumptions about the atmosphere, we obtain a pressure drop of 1.9 - 3.2 Pa if dust is to be raised. We only saw few pressure drops this large in Sols 0-102. However, the features do not need to pass directly over the lander and the pressures could be lower than the minima we measure. Furthermore, the response time of the pressure sensor is of order 3-5 s so it may not capture peak pressure perturbations. Thus, more dust devils may have occurred near the Phoenix site, but most of our detected vortices would be ghostly, dustless devils. Modelling: Using a Large Eddy Simulation model, we can simulate highly convective boundary layers on Mars [2]. The typical vortex has a diameter of 150 m, and extends up to 1 km. Further calculations give an incidence of 11 vortex events per day that could be compatible with the LES simulations. Deeper investigation of this is planned -but the numbers are roughly compatible. If the significant pressure signatures are limited to the center of the vortex then 5 per sol might be appropriate. The Phoenix mission has collected a unique set of in situ meteorological data from the Arctic regions on Mars. Modelling work shows that vertically oriented vortices with low pressure, warm cores, can develop on internal boundaries, such as those associated with cellular convection, and this is supported by observations. Simple cyclostrophic estimates of vortex wind speeds suggest that dust devils will form, but that most vortices will not be capable of lifting dust from the surface. So, at least in the first 102 sols, most of the Phoenix devils are dustless. References [1] F Ferri, PH Smith, M Lemmon, NO Renno; (2003) Dust devils as observed by Mars Pathfinder. JGR,108, NO. E12, 5133, doi:10.1029/2000JE001421. [2] Gheynani, B.T. and Taylor, P.A., (2008), Large Eddy Simulation of vertical vortices in highly convective Martian boundary layer, Paper 10 B.6, 18th Symposium on Boundary Layers and Turbulence, June 2008, Stockholm, Sweden

  4. Effect of Running Parameters on Flow Boiling Instabilities in Microchannels.

    PubMed

    Zong, Lu-Xiang; Xu, Jin-Liang; Liu, Guo-Hua

    2015-04-01

    Flow boiling instability (FBI) in microchannels is undesirable because they can induce the mechanical vibrations and disturb the heat transfer characteristics. In this study, the synchronous optical visualization experimental system was set up. The pure acetone liquid was used as the working fluid, and the parallel triangle silicon microchannel heat sink was designed as the experimental section. With the heat flux ranging from 0-450 kW/m2 the microchannel demand average pressure drop-heater length (Δp(ave)L) curve for constant low mass flux, and the demand pressure drop-mass flux (Δp(ave)G) curve for constant length on main heater surface were obtained and studied. The effect of heat flux (q = 188.28, 256.00, and 299.87 kW/m2), length of main heater surface (L = 4.5, 6.25, and 8.00 mm), and mass flux (G = 188.97, 283.45, and 377.94 kg/m2s) on pressure drops (Ap) and temperatures at the central point of the main heater surface (Twc) were experimentally studied. The results showed that, heat flux, length of the main heater surface, and mass flux were identified as the important parameters to the boiling instability process. The boiling incipience (TBI) and critical heat flux (CHF) were early induced for the lower mass flux or the main heater surface with longer length. With heat flux increasing, the pressure drops were linearly and slightly decreased in the single liquid region but increased sharply in the two phase flow region, in which the flow boiling instabilities with apparent amplitude and long period were more easily triggered at high heat flux. Moreover, the system pressure was increased with the increase of the heat flux.

  5. Numerical and experimental analysis of the transitional flow across a real stenosis.

    PubMed

    Agujetas, R; Ferrera, C; Marcos, A C; Alejo, J P; Montanero, J M

    2017-08-01

    In this paper, we present a numerical study of the pulsatile transitional flow crossing a severe real stenosis located right in front of the bifurcation between the right subclavian and right common carotid arteries. The simulation allows one to determine relevant features of this subject-specific flow, such as the pressure waves in the right subclavian and right common carotid arteries. We explain the subclavian steal syndrome suffered by the patient in terms of the drastic pressure drop in the right subclavian artery. This pressure drop is caused by both the diverging part of the analyzed stenosis and the reverse flow in the bifurcation induced by another stenosis in the right internal carotid artery.

  6. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles. [for combustion studies

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1977-01-01

    A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.

  7. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1977-01-01

    A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.

  8. Effect of Topical Calcium Channel Blockers on Intraocular Pressure in Steroid-induced Glaucoma.

    PubMed

    Ganekal, Sunil; Dorairaj, Syril; Jhanji, Vishal; Kudlu, Krishnaprasad

    2014-01-01

    To evaluate the effect of 0.125% verapamil and 0.5% diltiazem eye drops on intraocular pressure (IOP) in steroid-induced glaucoma in rabbit eyes. A total of 18 rabbits with steroid-induced glaucoma were divided into three groups (A, B and C; n = 6 each). Right eyes in groups A, B and C received 0.5% diltiazem, 0.125% verapamil and 0.5% timolol eye drops twice daily for 12 days, respectively; whereas, left eyes received distilled water. IOP was measured with Tono-pen XL at baseline, day 4, day 8, and day 12 of treatment. Both 0.5% diltiazem and 0.125% verapamil eye drops significantly reduced IOP compared to control eyes (p < 0.05). Reduction of IOP by 0.5% diltiazem, 0.125% verapamil eye drops were comparable to 0.5% timolol. No surface toxicity or systemic side effects were noted during the study period. Calcium channel blockers, verapamil, and diltia-zem significantly reduced IOP in rabbiteyes. This group of drugs may have a potential role in treatment of glaucoma How to cite this article: Ganekal S, Dorairaj S, Jhanji V, Kudlu K. Effect of Topical Calcium Channel Blockers on Intraocular Pressure in Steroid-induced Glaucoma. J Current Glau Prac 2014;8(1):15-19.

  9. Pulse Wave Amplitude Drops during Sleep are Reliable Surrogate Markers of Changes in Cortical Activity

    PubMed Central

    Delessert, Alexandre; Espa, Fabrice; Rossetti, Andrea; Lavigne, Gilles; Tafti, Mehdi; Heinzer, Raphael

    2010-01-01

    Background: During sleep, sudden drops in pulse wave amplitude (PWA) measured by pulse oximetry are commonly associated with simultaneous arousals and are thought to result from autonomic vasoconstriction. In the present study, we determine whether PWA drops were associated with changes in cortical activity as determined by EEG spectral analysis. Methods: A 20% decrease in PWA was chosen as a minimum for a drop. A total of 1085 PWA drops from 10 consecutive sleep recordings were analyzed. EEG spectral analysis was performed over 5 consecutive epochs of 5 seconds: 2 before, 1 during, and 2 after the PWA drop. EEG spectral analysis was performed over delta, theta, alpha, sigma, and beta frequency bands. Within each frequency band, power density was compared across the five 5-sec epochs. Presence or absence of visually scored EEG arousals were adjudicated by an investigator blinded to the PWA signal and considered associated with PWA drop if concomitant. Results: A significant increase in EEG power density in all EEG frequency bands was found during PWA drops (P < 0.001) compared to before and after drop. Even in the absence of visually scored arousals, PWA drops were associated with a significant increase in EEG power density (P < 0.001) in most frequency bands. Conclusions: Drops in PWA are associated with a significant increase in EEG power density, suggesting that these events can be used as a surrogate for changes in cortical activity during sleep. This approach may prove of value in scoring respiratory events on limited-channel (type III) portable monitors. Citation: Delessert A; Espa F; Rossetti A; Lavigne G; Tafti M; Heinzer R. Pulse wave amplitude drops during sleep are reliable surrogate markers of changes in cortical activity. SLEEP 2010;33(12):1687-1692. PMID:21120131

  10. Drop-Weight Impact Test on U-Shape Concrete Specimens with Statistical and Regression Analyses

    PubMed Central

    Zhu, Xue-Chao; Zhu, Han; Li, Hao-Ran

    2015-01-01

    According to the principle and method of drop-weight impact test, the impact resistance of concrete was measured using self-designed U-shape specimens and a newly designed drop-weight impact test apparatus. A series of drop-weight impact tests were carried out with four different masses of drop hammers (0.875, 0.8, 0.675 and 0.5 kg). The test results show that the impact resistance results fail to follow a normal distribution. As expected, U-shaped specimens can predetermine the location of the cracks very well. It is also easy to record the cracks propagation during the test. The maximum of coefficient of variation in this study is 31.2%; it is lower than the values obtained from the American Concrete Institute (ACI) impact tests in the literature. By regression analysis, the linear relationship between the first-crack and ultimate failure impact resistance is good. It can suggested that a minimum number of specimens is required to reliably measure the properties of the material based on the observed levels of variation. PMID:28793540

  11. Effects of sudden air pressure changes on hospital admissions for cardiovascular diseases in Prague

    NASA Astrophysics Data System (ADS)

    Kysely, Jan; Plavcova, Eva

    2013-04-01

    Sudden weather changes have long been supposed to be associated with negative impacts on human health. However, relatively few studies attempted to quantify these relationships. In this study, we use large 6-hour changes of atmospheric sea level pressure as proxy for sudden weather changes, and evaluate their association with hospital admissions for cardiovascular diseases. Winter and summer seasons and positive and negative pressure changes are analyzed separately, using data for the city of Prague (population of 1.2 million) over 16-year period (1994-2009). We find that sudden pressure drops in winter are associated with significant increases in the number of hospital admissions. Increases in morbidity are not observed for pressure drops in summer, nor pressure increases in any season. Analysis of synoptic weather maps shows that the large pressure drops in winter are associated with strong zonal (westerly) flow and rapidly moving low pressure systems with centres over Northern Europe and atmospheric fronts affecting the area of Western and Central Europe. Several of the largest pressure decreases were associated with infamous winter storms (such as Lothar on December 25, 1999 and Kyrill on January 18, 2007). Analysis of links between passages of strong atmospheric fronts and hospital admissions shows that the links are much weaker if weather changes are characterized by frontal passages. Since climate models project strengthening of the zonal circulation in winter and increased frequency of winter storms, the negative effects of such weather phenomena and their possible changes in a warmer climate of the 21st century need to be better understood, particularly as their importance in inducing excess morbidity and mortality in winter may increase compared to cold spells.

  12. Experimental Analysis of the Role of Fluid Transport Properties in Fluid-Induced Fracture Initiation and Propagation

    NASA Astrophysics Data System (ADS)

    Boutt, D.; McPherson, B. J.; Cook, B. K.; Goodwin, L. B.; Williams, J. R.; Lee, M. Y.; Patteson, R.

    2003-12-01

    It is well known that pore fluid pressure fundamentally influences a rock's mechanical response to stress. However, most measures of the mechanical behavior of rock (e.g. shear strength, Young's modulus) do not incorporate, either explicitly or implicitly, pore fluid pressure or transport properties of rock. Current empirical and theoretical criteria that define the amount of stress a given body of rock can support before fracturing also lack a direct connection between fluid transport and mechanical properties. Our research goal is to use laboratory experimental results to elucidate correlations between rock transport properties and fracture behavior under idealized loading conditions. In strongly coupled fluid-solid systems the evolution of the solid framework is influenced by the fluid and vice versa. These couplings often result in changes of the bulk material properties (i.e. permeability and failure strength) with respect to the fluid's ability to move through the solid and the solids ability to transmit momentum. Feedbacks between fluid and solid framework ultimately play key roles in understanding the spatial and temporal evolution of the coupled fluid-solid system. Discretely coupled models of fluid and solid mechanics were developed a priori to design an experimental approach for testing the role of fluid transport parameters in rock fracture. The experimental approach consists of first loading a fluid saturated cylindrical rock specimen under hydrostatic conditions and then applying a differential stress such that the maximum stress is perpendicular to the cylinder long axis. At the beginning of the test the minimum stress and the fluid pressure are dropped at the same time such that the resulting difference in the initial fluid pressure and the final fluid pressure is greater than the final minimum stress. These loading conditions should produce a fluid driven tensile fracture that is perpendicular to the cylinder long axis. Initial analyses using numerical simulations with similar boundary conditions suggest that resulting fracture propagation rates and fracture spacing are controlled by the rocks hydraulic diffusivity. Modeled rocks with higher permeability had fractures with larger apertures, more localized deformation, and greater fracture spacing. Intuitively, these results are consistent with permeability controlling the time required for pressure to come to equilibrium with the new boundary conditions. Finally, more general goals of this research include using these core-scale experimental data and discrete simulation results to calibrate larger-scale, more traditional continuum models of geologic deformation.

  13. Far-UV, visible, and near-IR reflectance spectra of frosts of H2O, CO2, NH3 and SO2

    NASA Technical Reports Server (NTRS)

    Hapke, B.; Wells, E.; Wagner, J.; Partlow, W.

    1981-01-01

    Measurements in the 0.1-2.5 micron range are presented for the reflectance spectra of the frosts of several volatiles pertinent to the study of comet nuclei. The frost spectra have distinctive features permitting their identification by spectroscopic reflectance remote sensing, notably in the far UV. It is found that: (1) H2O has a minimum at 0.16 microns and a maximum at 0.13 microns; (2) CO2 has minima near 0.21, 0.18 and 0.125 microns, with maxima at 0.19, 0.135 and 0.120 microns; (3) NH3 is bright at wavelengths longer than 0.21 microns, where reflectance drops to a value of only a few per cent at shorter wavelengths; (4) SO2 has a sharp drop at 0.32 microns, with a minimum at 0.18 microns and a maximum at 0.13 microns. The features in the frost spectra largely correspond to absorption line bands in the gas phase.

  14. 40 CFR 63.9921 - What are the installation, operation and maintenance requirements for my monitors?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) For the pressure drop CPMS, you must: (i) Locate the pressure sensor(s) in or as close to a position... calibration quarterly and transducer calibration monthly. (v) Conduct calibration checks any time the sensor exceeds the manufacturer's specified maximum operating pressure range, or install a new pressure sensor...

  15. 40 CFR 63.9921 - What are the installation, operation and maintenance requirements for my monitors?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) For the pressure drop CPMS, you must: (i) Locate the pressure sensor(s) in or as close to a position... calibration quarterly and transducer calibration monthly. (v) Conduct calibration checks any time the sensor exceeds the manufacturer's specified maximum operating pressure range, or install a new pressure sensor...

  16. 40 CFR 63.9921 - What are the installation, operation and maintenance requirements for my monitors?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) For the pressure drop CPMS, you must: (i) Locate the pressure sensor(s) in or as close to a position... calibration quarterly and transducer calibration monthly. (v) Conduct calibration checks any time the sensor exceeds the manufacturer's specified maximum operating pressure range, or install a new pressure sensor...

  17. 40 CFR 63.9921 - What are the installation, operation and maintenance requirements for my monitors?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) For the pressure drop CPMS, you must: (i) Locate the pressure sensor(s) in or as close to a position... calibration quarterly and transducer calibration monthly. (v) Conduct calibration checks any time the sensor exceeds the manufacturer's specified maximum operating pressure range, or install a new pressure sensor...

  18. Improved PFB operations: 400-hour turbine test results. [coal combustion products and hot corrosion in gas turbines

    NASA Technical Reports Server (NTRS)

    Rollbuhler, R. J.; Benford, S. M.; Zellars, G. R.

    1980-01-01

    A pressurized fluidized bed (PFB) coal-burning reactor was used to provide hot effluent gases for operation of a small gas turbine. Preliminary tests determined the optimum operating conditions that would result in minimum bed particle carryover in the combustion gases. Solids were removed from the gases before they could be transported into the test turbine by use of a modified two stage cyclone separator. Design changes and refined operation procedures resulted in a significant decrease in particle carryover, from 2800 to 93 ppm (1.5 to 0.05 grains/std cu ft), with minimal drop in gas temperature and pressure. The achievement of stable burn conditions and low solids loadings made possible a 400 hr test of small superalloy rotor, 15 cm (6 in.) in diameter, operating in the effluent. Blades removed and examined metallographically after 200 hr exhibited accelerated oxidation over most of the blade surface, with subsurface alumina penetration to 20 micron m. After 400 hours, average erosion loss was about 25 micron m (1 mil). Sulfide particles, indicating hot corrosion, were present in depletion zones, and their presence corresponded in general to the areas of adherent solids deposit. Sulfidation appears to be a materials problem equal in importance to erosion.

  19. Droplet squeezing through a narrow constriction: Minimum impulse and critical velocity

    NASA Astrophysics Data System (ADS)

    Zhang, Zhifeng; Drapaca, Corina; Chen, Xiaolin; Xu, Jie

    2017-07-01

    Models of a droplet passing through narrow constrictions have wide applications in science and engineering. In this paper, we report our findings on the minimum impulse (momentum change) of pushing a droplet through a narrow circular constriction. The existence of this minimum impulse is mathematically derived and numerically verified. The minimum impulse happens at a critical velocity when the time-averaged Young-Laplace pressure balances the total minor pressure loss in the constriction. Finally, numerical simulations are conducted to verify these concepts. These results could be relevant to problems of energy optimization and studies of chemical and biomedical systems.

  20. Shape oscillations of acoustically levitated drops in water: Early research with Bob Apfel on modulated radiation pressure

    NASA Astrophysics Data System (ADS)

    Marston, Philip L.

    2004-05-01

    In 1976, research in collaboration with Bob Apfel demonstrated that low-frequency shape oscillations of hydrocarbon drops levitated in water could be driven using modulated radiation pressure. While that response to modulated ultrasound was subsequently extended to a range of systems, the emphasis here is to recall the initial stages of development in Bob Apfel's laboratory leading to some publications [P. L. Marston and R. E. Apfel, J. Colloid Interface Sci. 68, 280-286 (1979); J. Acoust. Soc. Am. 67, 27-37 (1980)]. The levitation technology used at that time was such that it was helpful to develop a sensitive method for detecting weak oscillations using the interference pattern in laser light scattered by levitated drops. The initial experiments to verify this scattering method used shape oscillations induced by modulated electric fields within the acoustic levitator. Light scattering was subsequently used to detect shape oscillations induced by amplitude modulating a carrier having a high frequency (around 680 kHz) at a resonance of the transducer. Methods were also developed for quantitative measurements of the drop's response and with improved acoustic coupling drop fission was observed. The connection with research currently supported by NASA will also be noted.

  1. Leaf patch clamp pressure probe measurements on olive leaves in a nearly turgorless state.

    PubMed

    Ehrenberger, W; Rüger, S; Rodríguez-Domínguez, C M; Díaz-Espejo, A; Fernández, J E; Moreno, J; Zimmermann, D; Sukhorukov, V L; Zimmermann, U

    2012-07-01

    The non-invasive leaf patch clamp pressure (LPCP) probe measures the attenuated pressure of a leaf patch, P(p) , in response to an externally applied magnetic force. P(p) is inversely coupled with leaf turgor pressure, P(c) , i.e. at high P(c) values the P(p) values are small and at low P(c) values the P(p) values are high. This relationship between P(c) and P(p) could also be verified for 2-m tall olive trees under laboratory conditions using the cell turgor pressure probe. When the laboratory plants were subjected to severe water stress (P(c) dropped below ca. 50 kPa), P(p) curves show reverse diurnal changes, i.e. during the light regime (high transpiration) a minimum P(p) value, and during darkness a peak P(p) value is recorded. This reversal of the P(p) curves was completely reversible. Upon watering, the original diurnal P(p) changes were re-established within 2-3 days. Olive trees in the field showed a similar turnover of the shape of the P(p) curves upon drought, despite pronounced fluctuations in microclimate. The reversal of the P(p) curves is most likely due to accumulation of air in the leaves. This assumption was supported with cross-sections through leaves subjected to prolonged drought. In contrast to well-watered leaves, microscopic inspection of leaves exhibiting inverse diurnal P(p) curves revealed large air-filled areas in parenchyma tissue. Significantly larger amounts of air could also be extracted from water-stressed leaves than from well-watered leaves using the cell turgor pressure probe. Furthermore, theoretical analysis of the experimental P(p) curves shows that the propagation of pressure through the nearly turgorless leaf must be exclusively dictated by air. Equations are derived that provide valuable information about the water status of olive leaves close to zero P(c) . © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

  2. MGBX - PS Crouch with experiment module

    NASA Image and Video Library

    2016-08-12

    STS083-346-024 (4-8 April 1997) --- Payload specialist Roger K. Crouch performs the activation for the Mid Deck Glove Box (MGBX). Made to accommodate a variety of hardware and materials testing, the facility offers physical isolation and a negative air pressure environment so that items that are not suitable for handling in the open Spacelab can be protected. One experiment that was performed on STS-83 is the Internal Flows in a Free Drop (IFFD), an experiment that investigates rotation and position control of drops by varying acoustic pressures.

  3. Validation of CTF Droplet Entrainment and Annular/Mist Closure Models using Riso Steam/Water Experiments

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wysocki, Aaron J.; Salko, Robert K.

    This report summarizes the work done to validate the droplet entrainment and de-entrainment models as well as two-phase closure models in the CTF code by comparison with experimental data obtained at Riso National Laboratory. The Riso data included a series of over 250 steam/water experiments that were performed in both tube and annulus geometries over a range of various pressures and outlet qualities. Experimental conditions were set so that the majority of cases were in the annular/mist ow regime. Measurements included liquid lm ow rate, droplet ow rate, lm thickness, and two-phase pressure drop. CTF was used to model 180more » of the tubular geometry cases, matching experimental geometry, outlet pressure, and outlet ow quality to experimental values. CTF results were compared to the experimental data at the outlet of the test section in terms of vapor and entrained liquid ow fractions, pressure drop per unit length, and liquid lm thickness. The entire process of generating CTF input decks, running cases, extracting data, and generating comparison plots was scripted using Python and Matplotlib for a completely automated validation process. All test cases and scripting tools have been committed to the COBRA-TF master repository and selected cases have been added to the continuous testing system to serve as regression tests. The dierences between the CTF- and experimentally-calculated ow fraction values were con- sistent with previous calculations by Wurtz, who applied the same entrainment correlation to the same data. It has been found that CTF's entrainment/de-entrainment predictive capability in the annular/mist ow regime for this particular facility is comparable to the licensed industry code, COBRAG. While lm and droplet predictions are generally good, it has been found that accuracy is diminished at lower ow qualities. This nding is consistent with the noted deciencies in the Wurtz entrainment model employed by CTF. The CTF predicted two-phase pressure drop in the annular/mist ow regime has been found to be highly inaccurate, exhibiting a clear bias with respect to the experimental data. This inaccuracy led to an investigation that revealed deciencies in the implementation of the annular/mist interfacial friction model, which should be investigated further in the future. Looking to published COBRAG results for this same facility reveal it exhibits no bias with regard to experimental pressure drop results. In addition to the problems with pressure drop prediction, the lm thickness was also signicantly under-predicted by CTF compared to both experimental data and Wurtz's analytical calculations. Film thickness is calculated using a simple geometric relationship and lm void fraction in CTF, which is dependent on slip ratio and interfacial friction. It is possible that the issues aecting the pressure drop and lm void prediction are related.« less

  4. 42 CFR 84.82 - Gas pressure gages; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

  5. 42 CFR 84.82 - Gas pressure gages; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

  6. 42 CFR 84.82 - Gas pressure gages; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

  7. 42 CFR 84.82 - Gas pressure gages; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

  8. 42 CFR 84.82 - Gas pressure gages; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Gas pressure gages; minimum requirements. 84.82 Section 84.82 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self...

  9. Numerical investigation of cavitation flow inside spool valve with large pressure drop

    NASA Astrophysics Data System (ADS)

    Deng, Jian; Pan, Dingyi; Xie, Fangfang; Shao, Xueming

    2015-12-01

    Spool valves play an important role in fluid power system. Cavitation phenomena happen frequently inside the spool valves, which cause structure damages, noise and lower down hydrodynamic performance. A numerical tools incorporating the cavitation model, are developed to predict the flow structure and cavitation pattern in the spool valve. Two major flow states in the spool valve chamber, i.e. flow-in and flow-out, are studies. The pressure distributions along the spool wall are first investigated, and the results agree well with the experimental data. For the flow-in cases, the local pressure at the throttling area drops much deeper than the pressure in flow-out cases. Meanwhile, the bubbles are more stable in flow-in cases than those in flow-out cases, which are ruptured and shed into the downstream.

  10. A Hybrid Windkessel Model of Blood Flow in Arterial Tree Using Velocity Profile Method

    NASA Astrophysics Data System (ADS)

    Aboelkassem, Yasser; Virag, Zdravko

    2016-11-01

    For the study of pulsatile blood flow in the arterial system, we derived a coupled Windkessel-Womersley mathematical model. Initially, a 6-elements Windkessel model is proposed to describe the hemodynamics transport in terms of constant resistance, inductance and capacitance. This model can be seen as a two compartment model, in which the compartments are connected by a rigid pipe, modeled by one inductor and resistor. The first viscoelastic compartment models proximal part of the aorta, the second elastic compartment represents the rest of the arterial tree and aorta can be seen as the connection pipe. Although the proposed 6-elements lumped model was able to accurately reconstruct the aortic pressure, it can't be used to predict the axial velocity distribution in the aorta and the wall shear stress and consequently, proper time varying pressure drop. We then modified this lumped model by replacing the connection pipe circuit elements with a vessel having a radius R and a length L. The pulsatile flow motions in the vessel are resolved instantaneously along with the Windkessel like model enable not only accurate prediction of the aortic pressure but also wall shear stress and frictional pressure drop. The proposed hybrid model has been validated using several in-vivo aortic pressure and flow rate data acquired from different species such as, humans, dogs and pigs. The method accurately predicts the time variation of wall shear stress and frictional pressure drop. Institute for Computational Medicine, Dept. Biomedical Engineering.

  11. 25 CFR 543.18 - What are the minimum internal control standards for the cage, vault, kiosk, cash and cash...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... available upon demand for each day, shift, and drop cycle (this is not required if the system does not track..., beverage containers, etc., into and out of the cage. (j) Variances. The operation must establish, as...

  12. 25 CFR 543.18 - What are the minimum internal control standards for the cage, vault, kiosk, cash and cash...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... available upon demand for each day, shift, and drop cycle (this is not required if the system does not track..., beverage containers, etc., into and out of the cage. (j) Variances. The operation must establish, as...

  13. Generalization of low pressure, gas-liquid, metastable sound speed to high pressures

    NASA Technical Reports Server (NTRS)

    Bursik, J. W.; Hall, R. M.

    1981-01-01

    A theory is developed for isentropic metastable sound propagation in high pressure gas-liquid mixtures. Without simplification, it also correctly predicts the minimum speed for low pressure air-water measurements where other authors are forced to postulate isothermal propagation. This is accomplished by a mixture heat capacity ratio which automatically adjusts from its single phase values to approximately the isothermal value of unity needed for the minimum speed. Computations are made for the pure components parahydrogen and nitrogen, with emphasis on the latter. With simplifying assumptions, the theory reduces to a well known approximate formula limited to low pressure.

  14. 42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

  15. 42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

  16. 42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

  17. 42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

  18. 42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...

  19. 40 CFR Table 7 to Subpart Ddddd of... - Establishing Operating Limits

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... Particulate matter, mercury, or total selected metals a. Wet scrubber operating parameters i. Establish a site... drop and liquid flow rate monitors and the particulate matter, mercury, or total selected metals... from the pressure drop and liquid flow rate monitors and the particulate matter, mercury, or total...

  20. Barriers Keep Drops Of Water Out Of Infrared Gas Sensors

    NASA Technical Reports Server (NTRS)

    Murray, Sean K.

    1996-01-01

    Infrared-sensor cells used for measuring partial pressures of CO(2) and other breathable gases modified to prevent entry of liquid water into sensory optical paths of cells. Hydrophobic membrane prevents drops of water entrained in flow from entering optical path from lamp to infrared detectors.

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