Water drops impacting windshields of high-speed trains and aircraft as well as blades in steam turbine power generators obliquely and at high speeds are difficult to repel. Impacting drops penetrate the void regions of nanotextured and microtextured superhydrophobic coatings, with this pinning resulting in the loss of drop mobility. In order to repel high-speed water drops , we nanotextured polymer surfaces with nanowire bundles separated from their neighbors by microscale void regions, with the nanowires in a bundle separated from their neighbors by nanoscale void regions.
Water drops with speeds below a critical speed rebound completely. Water drops with speeds exceeding a critical speed rebound partially, but residual droplets that begin to be pinned undergo a spontaneous dewetting process and slide off. The natural oscillations of residual droplets drive this dewetting process in the interbundle void regions, resulting in a transition from the sticky Wenzel state to the slippery Cassie state without external stimuli. Thermal imaging of levitated fresh and salt water drops during laser irradiation. Simulation of high energy laser propagation and scattering in the maritime environment is problematic, due to the high likelihood of turbulence, fog, and rain or sea spray within the beam path.
Considering large water drops diameters of approximately 1-mm , such as those found in a light rain, an incident high energy laser will lead to rapid evaporation of the water drop as it traverses the beam path. These measurements show that the steady-state surface temperature of the drop is well below the saturation temperature, and for pure substances the equilibrium temperature decreases with decreasing drop volume similar to observations with smaller aqueous aerosols.
Temperature non-uniformity within the drop is also assessed from statistics of the surface temperature fluctuations. Preliminary results from irradiated salt water drops show notably different behavior from fresh water drops , including temperature spikes as the drop volume decreases and occasional nucleate boiling. An experiment vehicle plunges into the deceleration pit at the end of a 5. The Zero-Gravity Research Facility was developed to support microgravity research and development programs that investigate various physical sciences, materials, fluid physcis, and combustion and processing systems.
Payloads up to 1 meter in diameter and kg in weight can be accommodated. The facility has a meter evacuated shaft to ensure a disturbance-free drop. This is No. The Zero-Gravity Research Facility was developed to support microgravity research and development programs that investigate various physical sciences, materials, fluid physics, and combustion and processing systems. An experiment vehicle plunges into the deceleration at the end of a 5.
Payloads up to one-meter in diameter and kg in weight can be accommodated. Payloads up to one meter in diameter and kg in weight can be accommodated. Evaporation of oil- water emulsion drops when heated at high temperature. An experimental study on conditions and main characteristics for high-temperature more than K evaporation of oil- water drops is presented. The high-temperature water purification from impurities can be the main practical application of research results. Thus, the heating of drops is implemented by the two typical schemes: In the latter case, the heating conditions correspond to those attained while moving water drops with impurities in a counter high-temperature gaseous flow in the process of water purification.
Evaporation time as function of heating temperature is presented. The influence of oil product concentration in an emulsion drop on evaporation characteristics is discussed. The conditions for intensive flash boiling of an emulsion drop and its explosive breakup with formation of the fine droplets cloud are pointed out. Heat fluxes required for intensive flash boiling and explosive breakup of a drop with further formation of the fine aerosol are determined in the boundary layer of a drop. The fundamental differences between flash boiling and explosive breakup of an emulsion drop when heated on a substrate and in a flow of the heated air are described.
The main prospects for the development of the high-temperature water purification technology are detailed taking into account the fast emulsion drop breakup investigated in the paper. Experimental determination of forces applied by liquid water drops at high drop velocities impacting a glass plate with and without a shallow water layer using wavelet deconvolution. Time-dependent forces applied by 2 and 4. Both approaches are in close agreement for drops falling on dry glass. However, only the wavelet approach is able to measure natural features of the splash on shallow water layers that impart forces to the plate after the initial impact.
At relatively high velocities including terminal velocity the measured peak force from the initial impact is significantly higher than that predicted by idealised drop shape models and models from Roisman et al. Hence empirical formulae are developed for the initial time-dependent impact force from drops falling at a different velocities up to and including terminal velocity onto a dry glass surface, b terminal velocity onto dry glass or glass with a water layer and c different velocities below terminal velocity onto dry glass or glass with a water layer.
For drops on dry glass, the empirical formulae are applicable to a glass plate or a composite layered plate with a glass surface, although they apply to other plate thicknesses and are applicable to any plate material with a similar surface roughness and wettability. The measurements also indicate that after the initial impact there can be high level forces when bubbles are entrained in the water layer. Internally damped, self-arresting vertical drop -weight impact test apparatus. Ambur, Damodar R. Inventor ; Prasad, Chunchu B. Inventor ; Waters, Jr. Inventor ; Stockum, Robert W.
Inventor ; Walter, Manfred A. A vertical dropped -weight impact test machine has a dropped -weight barrel vertically supported on upper and lower support brackets. The dropped -weight barrel is chambered to receive a dropped -weight assembly having a latch pin at its upper end, a damping unit in the middle, and a tup at its lower end. The tup is adapted for gathering data during impact testing. The latch pin releasably engages a latch pin coupling assembly. The latch pin coupling assembly is attached to a winch via a halyard for raising and lowering the dropped -weight assembly.
The lower end of the dropped -weight barrel is provided with a bounce-back arresting mechanism which is activated by the descending passage of the dropped -weight assembly. After striking the specimen, the dropped -weight assembly rebounds vertically and is caught by the bounce-back arresting mechanism. The damping unit of the dropped -weight assembly serves to dissipate energy from the rebounding dropped -weight assembly and prevents the dropped -weight assembly from rebounding from the self-arresting mechanism.
Inventor ; Water, Manfred A. The air drop development test program for the Space Shuttle Solid Rocket Booster Recovery System required the design of a large drop test vehicle that would meet all the stringent requirements placed on it by structural loads, safety considerations, flight recovery system interfaces, and sequence. The drop test vehicle had to have the capability to test the drogue and the three main parachutes both separately and in the total flight deployment sequence and still be low-cost to fit in a low-budget development program.
The design to test large ribbon parachutes to loads of , pounds required the detailed investigation and integration of several parameters such as carrier aircraft mechanical interface, drop test vehicle ground transportability, impact point ground penetration, salvageability, drop test vehicle intelligence, flight design hardware interfaces, and packaging fidelity. Testing the Waters.
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Provides information about home drinking water treatment systems to address concerns about the safety and quality of drinking water. Discusses water testing , filtration, product options and selection, water testing resources, water treatment device guidelines, water analysis terminology, and laboratory selection. Estimation of dynamic stability parameters from drop model flight tests.
A recent NASA application of a remotely-piloted drop model to studies of the high angle-of-attack and spinning characteristics of a fighter configuration has provided an opportunity to evaluate and develop parameter estimation methods for the complex aerodynamic environment associated with high angles of attack. The paper discusses the overall drop model operation including descriptions of the model, instrumentation, launch and recovery operations, piloting concept, and parameter identification methods used.
Static and dynamic stability derivatives were obtained for an angle-of-attack range from deg to 53 deg. The results of the study indicated that the variations of the estimates with angle of attack were consistent for most of the static derivatives, and the effects of configuration modifications to the model such as nose strakes were apparent in the static derivative estimates. The dynamic derivatives exhibited greater uncertainty levels than the static derivatives, possibly due to nonlinear aerodynamics, model response characteristics, or additional derivatives.
The overall remotely piloted drop model operation, descriptions, instrumentation, launch and recovery operations, piloting concept, and parameter identification methods are discussed. Static and dynamic stability derivatives were obtained for an angle attack range from deg to 53 deg. It is indicated that the variations of the estimates with angle of attack are consistent for most of the static derivatives, and the effects of configuration modifications to the model were apparent in the static derivative estimates. Orion Swing Drop 6. In a series of tests , Orion is being dropped in a variety of different conditions to help fine-tune NASA's predictions of Orion's landing loads.
Transient effects in ice nucleation of a water drop impacting onto a cold substrate. The impact of water drops onto a solid surface at subfreezing temperatures has been experimentally studied. Drop nucleation has been observed using a high-speed video system. The statistics of nucleation allows the estimation of the average number of nucleation sites per unit area of the wetted part of the substrate. We have discovered that the nucleation rate in the impacting drop is not constant. The observed significant increase of the nucleation rate at small times after impact t drop impact.
These bubbles serve as additional nucleation sites and enhance the nucleation rate. A water drop on a superhydrophobic surface that is pinned by wire loops can be reproducibly cut without formation of satellite droplets. Drops placed on low-density polyethylene surfaces and Teflon-coated glass slides were cut with superhydrophobic knives of low-density polyethylene and treated copper or zinc sheets, respectively.
Distortion of drop shape by the superhydrophobic knife enables a clean break. The driving force for droplet formation arises from the lower surface free energy for two separate drops , and it is modeled as a 2-D system. An estimate of the free energy change serves to guide when droplets will form based on the variation of drop volume, loop spacing and knife depth. Combining the cutting process with an electrofocusing driving force could enable a reproducible biomolecular separation without troubling satellite drop formation. The small scale test method Dynamic drop test ; DDT which could evaluate disappearance characteristics of hydrophobicity easily was suggested.
This test is to evaluate resistance of a sample to loss of hydrophobicity due to moisture and simultaneous electric stress. As factors for deterioration of hydrophobicity on a sample in DDT, various factors such as electrical influence, physical influence by water droplets and so on were considered. In this study, we investigated two kinds of factors electrification and salt affecting deterioration of hydrophobicity on the surface of a silicone rubber until ignition of continuous electrical discharge in DDT.
Condensation of water from the atmosphere on a solid surface is an ubiquitous phenomenon in nature and has diverse technological applications, e. We investigated the condensation kinetics of water drops on a lubricant-impregnated surface, i. Growing and coalescing drops were imaged in 3D using a laser scanning confocal microscope equipped with a temperature and humidity control. Different stages of condensation can be discriminated. On a lubricant-impregnated hydrophobic micropillar array these are: The drop -substrate contact does not result in breakdown of the slippery behaviour.
Contrary, on a lubricant-impregnated hydrophilic micropillar array, the condensed water drops replace the lubricant. Consequently, the surface loses its slippery property. Our results demonstrate that a Wenzel-like to Cassie transition, required to maintain the facile removal of condensed water drops , can be induced by well-chosen surface hydrophobicity.
Surface temperature measurements of a levitated water drop during laser irradiation. Simulation of high energy laser propagation and scattering in the maritime environment is problematic, due to the high liklihood of turbulence, fog, and rain or sea spray within the beam path. Laser interactions with large water drops diameters of approximately 1-mm , such as those found in a light rain, have received relatively less attention. These measurements show that the steady-state surface temperature of the drop is well below the saturation temperature, yet based on the time history of the drop volume vaporization begins almost immediately upon laser strike.
Inferences on the turbulence characteristics within the drop are also made from measurements of the fluctuations in the surface temperature. Morris, Aaron L. Test and simulation techniques have evolved concurrently to keep up with the demands of a challenging and complex system. The goal of this paper is to provide a roadmap to future programs on the test technique challenges and obstacles involved in executing a large-scale, multi-year parachute test program.
A focus on flight simulation modeling and correlation to test techniques executed to obtain parachute performance parameters are presented. Calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Any subsonic, external, non-lifting flow can be accommodated; flow into, but not through, inlets also can be simulated. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Seven codes are described: Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.
Though getting astronauts safely into orbit and beyond has long been one of NASA? The Crew Exploration Vehicle? As one means for validating this system? Two aerodynamic profiles for the PC-DTV currently exist, though both share the same interior structure, and both have an Orion-representative weight of 20, lbf. Two extraction methods have been developed as well.
The decision as to which aerodynamic profile and extraction method to use is still not finalized. Additional CFD and stress analysis must be undertaken in order to determine the more desirable options, though at present the "boat tail" profile and the CMS2 extraction method seem to be the favored options in their respective categories.
Fabrication of the PC-DTV and the selected extraction sled is set to begin in early October with an anticipated first drop test in mid-March The aim of the present work was to develop a method based on image analysis for describing soil detachment caused by the impact of a single water drop. The method consisted of recording tracks made by splashed particles on blotting paper under an optical microscope.
Additionally, the following relationships were determined: Furthermore, the proposed method allowed estimation of the weight of soil transported by a single water drop splash in relation to the distance of the water drop impact. It was concluded that the method of image analysis of splashed particles facilitated analysing the results at very low water drop energy and generated by single water drops.
Instrumentation and telemetry systems for free-flight drop model testing. This paper presents instrumentation and telemetry system techniques used in free-flight research drop model testing at the NASA Langley Research Center. The free-flight drop model test technique is used to conduct flight dynamics research of high performance aircraft using dynamically scaled models. The free-flight drop model flight testing supplements research using computer analysis and wind tunnel testing.
The drop models are scaled to approximately 20 percent of the size of the actual aircraft. The paper describes three telemetry downlinks used to acquire the data, video, and radar tracking information from the model. Also described are two telemetry uplinks, one used to fly the model employing a ground-based flight control computer and a second to activate commands for visual tracking and parachute recovery of the model.
The paper concludes with a discussion of free-flight drop model instrumentation and telemetry system development currently in progress for future drop model projects at the NASA Langley Research Center. Negative pressures and spallation in water drops subjected to nanosecond shock waves. 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. 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.
Initial basalt target site selection evaluation for the Mars penetrator drop test. Potential basalt target sites for an air drop penetrator test were described and the criteria involved in site selection were discussed. A summary of the background field geology and recommendations for optimum sites are also presented. Influence of solidification on the impact of supercooled water drops onto cold surfaces. 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 to and from to , 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. 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.
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A finite element model of an ATR commuter-class aircraft was developed and a crash simulation was executed. Analytical predictions were correlated with data obtained from a feet per second 9. The purpose of the test was to evaluate the structural response of the aircraft when subjected to a severe, but survivable, impact. The aircraft was configured with seats, dummies, luggage, and other ballast.
The wings were filled with 8, lb. The finite element model, which consisted of 57, nodes and 62, elements, was developed from direct measurements of the airframe geometry. The seats, dummies, luggage, simulated engines and fuel, and other ballast were represented using concentrated masses. The model was executed in LS-DYNA, a commercial finite element code for performing explicit transient dynamic simulations. Analytical predictions of structural deformation and selected time-history responses were correlated with experimental data from the drop test to validate the simulation.
Fluid-structure interaction analysis of the drop impact test for helicopter fuel tank. The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid-structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian-Eulerian method was constructed to elucidate the dynamic failure behavior.
The drop impact tests were conducted to validate the accuracy of the numerical simulation. Good agreement was achieved between the experimental and numerical results of the impact force with the ground. The influences of the impact velocity, the impact angle, the thickness of the fuel tank wall and the volume fraction of water on the dynamic responses of the dropped fuel tank were studied. The results indicated that the corner of the fuel tank is the most vulnerable location during the impact with ground.
A test failure dramatically points out a design weakness or the limits of the material in the test article. On air drop 3, the ft drogue parachute was totally destroyed 0. The parachute failure investigation, based on analysis of drop test data and supporting ground element test results is presented. Drogue design modifications are also discussed.
Because of unanticipated technical and engineering difficulties, POC was unable to fit their instrument into an aircraft pod. Each landing gear unit must be tested in the attitude simulating the landing condition that is most A rational method may be used in computing a main gear static Droplet combustion experiment drop tower tests using models of the space flight apparatus. The Droplet Combustion Experiment DCE is an experiment that is being developed to ultimately operate in the shuttle environment middeck or Spacelab.
The current experiment implementation is for use in the 2. Initial results were reported in the symposium of this meeting. Since then significant progress was made in drop tower instrumentation. The 2. Some very low velocity deployments of ignited droplets were observed. An engineering model was built at TRW. This model will be used in the 5 sec drop tower operation to obtain science data.
In addition, it was built using the flight design except for changes to accommodate the drop tower requirements. The mechanical and electrical assemblies have the same level of complexity as they will have in flight. The model was then integrated into the 5 sec drop tower. The model is currently undergoing initial operational tests prior to starting the science tests. Dropping in on a Clean Room Webb Test.
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Its experimental main parachute cluster deployment technique and off-the-shelf hardware necessitated a full-scale drop test prior to the MLAS mission in order to reduce overall mission risk. This test was successfully conducted at Wallops Flight Facility on March 6, , with all vehicle and parachute systems functioning as planned. This document captures the design, concept of operations and results of the drop test.
The DSS is an executable code that simulates the dynamics of airdropped cargo from first motion in an aircraft through landing. The bare DSS is difficult to use; the front end makes it easy to use. All inputs to the DSS, control of execution of the DSS, and postprocessing and plotting of outputs are handled in the front end. The front end is graphics-intensive. The Excel software provides the graphical elements without need for additional programming. Categories of input parameters are divided into separate tabbed windows. Pop-up comments describe each parameter.
An error-checking software component evaluates combinations of parameters and alerts the user if an error results. Case files can be created from inputs, making it possible to build cases from previous ones. Simulation output is plotted in 16 charts displayed on a separate worksheet, enabling plotting of multiple DSS cases with flight- test data. Variables assigned to each plot can be changed.
Selected input parameters can be edited from the plot sheet for quick sensitivity studies. The seats, dummies, luggage, fuel, and other ballast were represented using concentrated masses. Predictions of structural deformation and selected time-history responses were generated. The simulation was successfully validated through extensive test -analysis correlation.
Thermal stabilities of drops of burning thermoplastics under the UL 94 vertical test conditions. The properties of polymer melts will strongly affect the fire hazard of the pool induced by polymer melt flow. In this study the thermal stabilities of eight thermoplastic polymers as well as their melting drops generated under the UL 94 vertical burning test conditions were investigated by thermogravimetric experiments. It was found that the kinetic compensation effect existed for the decomposition reactions of the polymers and their drops. For polymethylmethacrylate PMMA , high impact polystyrene HIPS , poly acrylonitrile-butadiene-styrene ABS , polyamide 6 PA6 , polypropylene PP and low density polyethylene LDPE , the onset decomposition temperature and the two decomposition kinetic parameters the pre-exponential factor and the activation energy of the drop were less than those of the polymer.
However, the onset decomposition temperature and the two kinetic parameters of PC's drop were greater than those of polycarbonate PC. Interestingly, for polyethylenevinylacetate EVA18 the drop hardly contained the vinyl acetate chain segments. All rights reserved. Discusses an experiment which introduces students to the effects of electrical forces on the motion of macroscopic objects.
Included are the proecedures of measuring the charge-to-mass ratio from deflections of charged water drops in horizontal fields and the overall charges delivered in a Faraday cup. 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.
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 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. Primary acoustic signal structure during free falling drop collision with a water surface. Consistent optical and acoustic techniques have been used to study the structure of hydrodynamic disturbances and acoustic signals generated as a free falling drop penetrates water.
The relationship between the structures of hydrodynamic and acoustic perturbations arising as a result of a falling drop contacting with the water surface and subsequent immersion into water is traced. The primary acoustic signal is characterized, in addition to stably reproduced features steep leading edge followed by long decay with local pressure maxima , by irregular high-frequency packets, which are studied for the first time. Football helmet drop tests on different fields using an instrumented Hybrid III head. The head was dropped 0. Six repeat tests were conducted for each surface at 0.
The Hybrid III was instrumented with triaxial accelerometers to determine head responses for the different playing surfaces. For the 0. The lowest response was with Astroplay, followed by the engineered natural turf. Gameday and Fieldturf involved higher responses.
The differences between surfaces decreased in the 1. The cold weather testing involved higher accelerations, HIC 15 and delta V for each surface. The helmet drop test used in this study provides a simple and convenient means of evaluating the compliance and energy absorption of football playing surfaces. The type and temperature of the playing surface influence head responses.
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Study on bouncing motion of a water drop collision on superhydrophobic surface under icing conditions. When micro droplets in the air are supercooled and collide with the object, they froze on the surface at the time of a collision and can be defined as icing. If supercooled water droplets collide with an airfoil of an aircraft in flight and shape changes, there is a danger of losing lift and falling.
In this system, colliding water droplets are melted by the heat of the heater at the tip of the blade, and the water droplet is bounced by the aerodynamic force on the rear superhydrophobic coating. Thus, it prevents the phenomenon of icing again at the back of the wing runback ice. Therefore, it is possible to suppress power consumption of the electric heater. In that system, it is important to withdraw water droplets at an extremely superhydrophobic surface at an early stage. However, research on bouncing phenomenon on superhydrophobic surface under icing conditions are not done much now.
Therefore, in our research, we focus on one drop supercooled water droplet that collides with the superhydrophobic surface in the icing phenomenon, and aim to follow that phenomenon. In this report, the contact time is defined as the time from collision of a water droplet to bouncing from the superhydrophobic surface, and various parameters temperature, speed, and diameter on water droplets under icing conditions are set as the water drop bouncing time contact time of the product.
This test was performed to evaluate the structural integrity of a conformable auxiliary fuel tank mounted beneath the floor and to determine its effect on the impact response of the airframe structure and the occupants. To perform this simulation, a full-scale 3-dimensional finite element model of the fuselage section was developed using the explicit, nonlinear transient-dynamic finite element code, MSC. The emphasis of the simulation was to predict the structural deformation and floor-level acceleration responses obtained from the drop test of the B fuselage section with the auxiliary fuel tank.
Vertical drop test of a transport fuselage section located forward of the wing. A Boeing fuselage section was drop tested at the NASA Langley Research Center to measure structural, seat, and occupant response to vertical crack loads. Post- test inspection showed that the section bottom collapsed inward approximately 2 ft. Preliminary data traces indicated maximum normal accelerations of 20 g on the fuselage bottom, 10 to 12 g on the cabin floor, and 6.
Comparison of hemagglutination inhibition test and ELISA in quantification of antibodies to egg drop syndrome virus. In testing chicken sera it was found to have a The ELISA was efficacious in quantification of both vaccinal and infection antibodies and could routinely be used for screening large numbers of field sera. 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. Inlet oil- water flow rates were varied from to barrels-per-day in steps of With further increase in WC, friction pressure drop increases, this could be due to phase inversion. Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section.
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.
Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air- water mixtures at kPa abs and room temperature were used as the test fluids.
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Four flow regimes were identified visually: 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. Elemental Water Impact Test: Phase 1 Inch Hemisphere. Phase 1 of the EWIT series featured water impact tests of a inch hemisphere dropped from heights of 5 feet and 10 feet. The hemisphere was outfitted with an accelerometer and three pressure gages. The focus of this report is the correlation of analytical models against test data. The millennium water vapour drop in chemistry-climate model simulations.
The model simulations differ with respect to the prescribed sea surface temperatures SSTs and whether nudging is applied or not. The CCM EMAC is able to most closely reproduce the signature and pattern of the water vapour drop in agreement with those derived from satellite observations if the model is nudged.
Model results confirm that this extraordinary water vapour decline is particularly obvious in the tropical lower stratosphere and is related to a large decrease in cold point temperature. The drop signal propagates under dilution to the higher stratosphere and to the poles via the Brewer-Dobson circulation BDC. Correct observed SSTs are important for triggering the strong decline in water vapour. There are indications that, at least partly, SSTs contribute to the long period of low water vapour values from to For this period, the specific dynamical state of the atmosphere overall atmospheric large-scale wind and temperature distribution is important as well, as it causes the observed persistent low cold point temperatures.
These are induced by a period of increased upwelling, which, however, has no corresponding pronounced signature in SSTs anomalies in the tropics. Our free. Testing of a 4 K to 2 K heat exchanger with an intermediate pressure drop. 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. This paper will briefly discuss the theory, practical implementation and test results and analysis obtained to date.
Experimental and numerical study of drill bit drop tests on Kuru granite. This paper presents an experimental and numerical study of Kuru grey granite impacted with a seven-buttons drill bit mounted on an instrumented drop test machine. The force versus displacement curves during the impact, so-called bit-rock interaction BRI curves, were obtained using strain gauge measurements for two levels of impact energy. Moreover, the volume of removed rock after each drop test was evaluated by stereo-lithography three-dimensional surface reconstruction.
The influence of the impact energy and additional confining pressure on the BRI curves and the volume of the removed rock is discussed. In addition, the influence of the rock surface shape before impact was evaluated using two different mesh geometries: The experimental and numerical results are compared and discussed in terms of drilling efficiency through the mechanical specific energy.
This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. The force versus displacement curves during the impact, so-called bit—rock interaction BRI curves, were obtained using strain gauge measurements for two levels of impact energy. Multi-pumping flow system for the determination of boron in eye drops , drinking water and ocean water. A novel automated method for the determination of boron based on the use of pulsed flows was developed and applied to the determination of this element in samples of tap water , ocean water and eye drops.
The method was implemented by means of a multi-pumping system consisting of three solenoid micropumps and a photometric detector and exploits the reaction of azomethine-H in the presence of boron. The system runs under control of an open-source microcontroller. The main operational parameters were optimized. Given the particular kinetics of the reaction, a stopped-flow period 1 or 5min was included to allow for color development. The method presents linearity in the range 0.
In order to overcome matrix effect caused by the high saline concentration, ocean water samples required stop times of 5min, providing a sampling frequency of 10 samples h The method was considered accurate and fit for the purpose. For the past several years, many researchers are constantly developing and improving board level drop test procedures and specifications to quantify the solder joint reliability performance of consumer electronics products.
Predictive finite element analysis FEA by utilizing simulation software has become widely acceptable verification method which can reduce time and cost of the real-time test process. However, due to testing and metrological limitations it is difficult not only to simulate exact drop condition and capture critical measurement data but also tedious to calibrate the system to improve test methods.
In addition, one of the most challenging tasks is to quantify uniform stress and strain distribution throughout the test board and identify critical failure factors. The major contributions of this work are in the four aspects of the drop test in electronics as following. First of all, an analytical FEA model was developed to study the board natural frequencies and responses of the system with the consideration of dynamic stiffness, damping behavior of the material and effect of impact loading condition. An approach to find the key parameters that affect stress and strain distributions under predominate mode responses was proposed and verified with theoretical solutions.
Second, no ring phenomenon during the drop test was identified theoretically when the test board was modeled as both discrete system and continuous system. Numerical analysis was then conducted by FEA method for detailed geometry of attached chips with solder. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles. 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 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 A drop in performance on a fluid intelligence test due to instructed-rule mindset. A 'mindset' is a configuration of processing resources that are made available for the task at hand as well as their suitable tuning for carrying it out.
Of special interest, remote-relation abstract mindsets are introduced by activities sharing only general control processes with the task. To test the effect of a remote-relation mindset on performance on a Fluid Intelligence test Raven's Advanced Progressive Matrices, RAPM , we induced a mindset associated with little usage of executive processing by requiring participants to execute a well-defined classification rule 12 times, a manipulation known from previous work to drastically impair rule-generation performance and associated cognitive processes.
No drop was observed in a General Knowledge task. These results indicate strong most likely, transient adverse effects of a remote-relation mindset on test performance. They imply that although the trait of Fluid Intelligence has probably not changed, mindsets can severely distort estimates of this trait. Ultrafast cavitation induced by an X-ray laser in water drops. Cavitation in pure water is determined by an intrinsic heterogeneous cavitation mechanism, which prevents in general the experimental generation of large tensions negative pressures in bulk liquid water.
We developed an ultrafast decompression technique, based on the reflection of shock waves generated by an X-ray laser inside liquid drops , to stretch liquids to large negative pressures in a few nanoseconds.
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Using this method, we observed cavitation in liquid water at pressures below MPa. These large tensions exceed significantly those achieved previously, mainly due to the ultrafast decompression. The decompression induced by shock waves generated by an X-ray laser is rapid enough to continue to stretch the liquid phase after the heterogeneous cavitation occurs in water , despite the rapid growth of cavitation nanobubbles.
We developed a nucleation-and-growth hydrodynamic cavitation model that explains our results and estimates the concentration of heterogeneous cavitation nuclei in water. Harding Lawson Associates I Acoustics and hydrodynamics of a drop impact on a water surface. Hydrodynamic and acoustic processes associated with a drop impact on a water surface were studied experimentally. Acoustic signals were detected underwater with a hydrophone and in air with a microphone , the flow pattern was recorded with a high-speed camera, and the surface perturbation was monitored with a laser detector.
The dimensionless parameters of flows Reynolds, Froude, and Weber numbers induced by the impact varied with fall height within the ranges of drop and the surface and a series of acoustic packets attributable to the resonance emission of gas cavities. The top of the impact pulse, which was detected clearly in the entire fall height range, had a complex structure with short high-frequency and longer low-frequency oscillations.
The total number and the parameters of emitted acoustic packets depended to a considerable extent on the fall height. The cases of lacking, one-time, and repeated emission of packets were noted in a series of experiments performed at a constant fall height. The analysis of video data showed that the signal variability was induced by considerable differences in the scenarios of water entry of a drop , which assumed an ovoid shape at the end trajectory segment, in the mentioned experiments.
In June , a vertical drop test was conducted of a wing-box fuselage section of the same aircraft. Both sections were configured with two rows of aircraft seats, in a triple-double configuration. The forward fuselage section was also configured with luggage in the cargo hold. Both sections were outfitted with two hat racks, each with added ballast mass. The measured impact velocity for the forward fuselage section was The wing-box section was dropped with a downward facing pitch angle onto a sloping soil surface in order to create an induced forward acceleration in the airframe.
The vertical impact velocity of the wing-box section was A second objective of this project was to assess the capabilities of finite element simulations to predict the test responses. Finite element models of both fuselage sections were developed for execution in LS-DYNA Registered Trademark , a commercial explicit nonlinear transient dynamic code. The models contained accurate representations of the airframe structure, the hat racks and hat rack masses, the floor and seat tracks, the luggage in the cargo hold for the forward section, and the detailed under-floor structure in the wing-box section.
Initially, concentrated masses were used to represent the inertial properties of the seats, restraints, and ATD occupants. However, later simulations were performed that included finite element representations of the seats, restraints, and ATD occupants. These models were developed to more. This report describes an experimental program to assess the impact performance of a skid gear for use on the Wasp kit-built helicopter, which is marketed by HeloWerks, Inc.
In total, five vertical drop tests were performed. The test article consisted of a skid gear mounted beneath a steel plate. A seating platform was attached to the upper surface of the steel plate, and two 95th percentile Hybrid III male Anthropomorphic Test Devices ATDs were seated on the platform and secured using a four-point restraint system.
The test article also included ballast weights to ensure the correct position of the Center-of-Gravity CG. Twenty-six channels of acceleration data were collected per test at 50, samples per second. The five drop tests were conducted on two different gear configurations. The details of these test programs are presented, as well as an occupant injury assessment. Finally, a finite element model of the skid gear test article was developed for execution in LS-DYNA, an explicit nonlinear transient dynamic code, for predicting the skid gear and occupant dynamic responses due to impact.
Analysis and testing of a new method for drop size measurement using laser scatter interferometry. Research was conducted on a laser light scatter detection method for measuring the size and velocity of spherical particles. The method is based upon the measurement of the interference fringe pattern produced by spheres passing through the intersection of two laser beams. A theoretical analysis of the method was carried out using the geometrical optics theory. Experimental verification of the theory was obtained by using monodisperse droplet streams. Several optical configurations were tested to identify all of the parametric effects upon the size measurements.
Both off-axis forward and backscatter light detection were utilized. Simulated spray environments and fuel spray nozzles were used in the evaluation of the method. The measurements of the monodisperse drops showed complete agreement with the theoretical predictions. The method was demonstrated to be independent of the beam intensity and extinction resulting from the surrounding drops.
Signal processing concepts were considered and a method was selected for development. This investigation was conducted to obtain quantitative information on the effectiveness of three landing gears for the NY-2 consolidated training airplane. The investigation consisted of static, drop , and flight tests on landing gears of the oleo-rubber-disk and the mercury rubber-chord types, and flight tests only on a landing gear of the conventional split-axle rubber-cord type.
The results show that the oleo gear is the most effective of the three landing gears in minimizing impact forces and in dissipating the energy taken. A relatively simple method for measuring the dynamic crush response of foam materials at various loading rates is described. The method utilizes a drop mass impact configuration with mass and impact velocity selected such that the crush speed remains approximately uniform during the entire sample crushing event.
Instrumentation, data acquisition, and data processing techniques are presented, and limitations of the test method are discussed. The objective of the test method is to produce input data for dynamic finite element modeling involving crash and energy absorption characteristics of foam materials. Water Hammer Test. Instead of fuel, water is run through the propulsion system to make sure that the spacecraft holds up to vibrations caused by pressure oscillations.
The test was performed very early in the development of the mission, in , at Lockheed Martin Space Systems, Denver. Early testing was possible because Phoenix's main structure was already in place from the Mars Surveyor program. Nonthermal ice nucleation observed at distorted contact lines of supercooled water drops. Ice nucleation is the crucial step for ice formation in atmospheric clouds and therefore underlies climatologically relevant precipitation and radiative properties.
Some progress has been made in understanding the roles of temperature, supersaturation, and material properties, but an explanation for the efficient ice nucleation occurring when a particle contacts a supercooled water drop has been elusive for over half a century. Here, we explore ice nucleation initiated at constant temperature and observe that mechanical agitation induces freezing of supercooled water drops at distorted contact lines.
Several possible mechanisms are proposed to explain the observations. One plausible explanation among them, decreased pressure due to interface curvature, is explored theoretically and compared with the observational results quasiquantitatively. Indeed, the observed freezing-temperature increase scales with contact line speed in a manner consistent with the pressure hypothesis.
Whatever the mechanism, the experiments demonstrate a strong preference for ice nucleation at three-phase contact lines compared to the two-phase interface, and they also show that movement and distortion of the contact line are necessary contributions to stimulating the nucleation process. Act Now! Discover incredible discounts at Shun Melson.
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