Jet Apparatus Research Articles

Application of DLVO Energy Map To Evaluate Interactions between Spherical Colloids and Rough Surfaces

This study theoretically evaluated interactions between spherical colloids and rough surfaces in three-dimensional space using Derjaguin-Landau-Verwey- Overbeek (DLVO) energy/force map and curve. The rough surfaces were modeled as a flat surface covered by hemispherical protrusions. A modified Derjaguin approach was employed to calculate the interaction energies and forces. Results show that more irreversible attachments in primary minima occur at higher ionic strengths, which theoretically explains the observed hysteresis of colloid attachment and detachment during transients in solution chemistry. Secondary minimum depths can be increased significantly in concave regions (e.g., areas aside of asperities or between asperities) due to sidewall interactions. Through comparing the tangential attractive forces from asperities and the hydrodynamic drag forces in three-dimensional space, we showed that attachment in secondary minima can be located on open collector surfaces of a porous medium. This result challenges the usual belief that the attachment in secondary minima only occurs in stagnation point regions of the porous medium and is absent in shear flow systems such as parallel plate flow chamber and impinging jet apparatus. Despite the argument about the role of secondary minima in colloid attachment remained, our study theoretically justified the existence of attachment in secondary minima in the presence of surface roughness. Further, our study implied that the presence of surface roughness is more favorable for attachment in secondary minima than in primary minima under unfavorable chemical conditions.

Repair welding of cracks in engine turbine jet apparatus ring using high-power diode laser

The course of investigations on working out of technological conditions of automatic repair HPDL welding of longitudinal cracks in the web of the internal ring of the nozzle set of the TW2-117 engine turbine of the MI-8 helicopter made of EI-35(24-16-6) creep-resisting austenitic steel is described. Liquid-penetrant inspection and metallographic examination show high quality of repair joints.

Transparent, Superhydrophobic, and Wear-Resistant Coatings on Glass and Polymer Substrates Using SiO2, ZnO, and ITO Nanoparticles

It is of significant interest to create surfaces that simultaneously exhibit high water contact angle, low contact angle hysteresis, and high transmission of visible light, as well as mechanical wear resistance for industrial applications. The fabrication of such surfaces has often involved complex or expensive processes, required techniques that were not suitable for a variety of substrates and particles, required surface post-treatment, or lacked wear resistance. A systematic study has been performed in which transparent superhydrophobic surfaces were created on glass, polycarbonate, and poly(methyl methacrylate) (PMMA) substrates using surface-functionalized SiO(2), ZnO, and indium tin oxide (ITO) nanoparticles. The contact angle, contact angle hysteresis, and optical transmittance were measured for samples using all particle-substrate combinations. To examine wear resistance, multiscale wear experiments were performed using an atomic force microscope (AFM) and a water jet apparatus.

Multiple liquid impacts on polymeric matrix composites reinforced with carbon nanotubes

The exploration of innovative concepts and advanced materials that effectively can sustain flight conditions are crucial driving elements for the design of future generation aircraft. Particularly in the context of wear, the introduction of carbon nanotube reinforced composites as external surface materials for potential implementation in aeronautics, is gaining a great interest in light of the possible reinforcement effects that these materials can provide. In this study, water droplet impact threshold velocities ensuing in visible surface damage are determined for a selection of polymer matrix composites reinforced with multi-walled carbon nanotubes. Results are presented for the damage threshold curves obeying the relationship vDT∝Λ·n−β, where Λ and β are experimentally determined upon multiple liquid impacts, using Cavendish Laboratory's Multiple Impact Jet Apparatus (MIJA). The findings of this study convey that carbon nanotube reinforced resins do not exhibit significant beneficial erosion resilience effects with the employed level of carbon nanotube dispersion. Results for development of fracture are further discussed, based on the Hertzian fracture theory and Vickers hardness values of the considered materials. Additionally, theoretical values of material properties are presented, based on experimental acoustic impedance measurements.

Limestone Particle Attrition in High-Velocity Air Jets

Experiments were carried out with limestone particles of several narrow size intervals (125–180, 250–300, 355–425, 500–600, 600–710, 710–850, and 850–1037 μm) for times ranging from 0.5 to 144 h in a high-velocity jet apparatus to provide a more comprehensive understanding of jet attrition. The theory of cumulative damage for fatigue is applied to explain the particle attrition mechanisms and to build an attrition model. Fines generation processes differed for limestone particles of different initial sizes, especially in the initial stage, because of the effects of rough surfaces and cumulative damage needed for attrition. In the model, the fines generation rates in the initial stage was well fitted by an exponential function with an index inversely proportional to the particle volume until stable stages were reached, whereas the rate of fines generation during the stable stage appeared to be constant for narrowly sized limestone particles.

Durable Lotus-effect surfaces with hierarchical structure using micro- and nanosized hydrophobic silica particles

Surfaces with a very high apparent water contact angle (CA) and low water contact angle hysteresis (CAH) exhibit many useful characteristics, among them extreme water repellency, low drag for fluid flow, and a self-cleaning effect. The leaf of the Lotus plant (Nelumbo nucifera) achieves these properties using a hierarchical structure with roughness on both the micro- and nanoscale. It is of great interest to create durable surfaces with the so-called “Lotus effect” for many important applications. In this study, hierarchically structured surfaces with Lotus-effect properties were fabricated using micro- and nanosized hydrophobic silica particles and a simple spray method. In addition, hierarchically structured surfaces were prepared by spraying a nanoparticulate coating over a micropatterned surface. To examine the similarities between surfaces using microparticles versus a uniform micropattern as the microstructure, CA and CAH were compared across a range of pitch values for the two types of microstructures. Wear experiments were performed using an atomic force microscope (AFM), a ball-on-flat tribometer, and a water jet apparatus to verify multiscale wear resistance. These surfaces have potential uses in engineering applications requiring Lotus-effect properties and high durability.

Assessing the resistance of metal matrix composites and their microstructural integrity under erosion–corrosion

Abstract Materials and machinery components handling corrosive slurries are exposed to erosion–corrosion (EC) processes that significantly reduce their service lifetime. Difficulties predicting material loss in industrial machinery, financial and security impacts due to early failure of worn components and the necessity of managing highly aggressive slurries (e.g. oilsands), have motivated the application of surface engineering solutions to reduce the negative effects of erosion–corrosion processes. The erosion–corrosion resistance of nickel base and iron base metal matrix composites (C Ni and C Fe MMCs, respectively) coatings was studied in this paper. The behavior of the MMCs compared with their non-reinforced matrices (NRMs); tungsten carbides (WC) particles were used to reinforce the NRMs. The microstructures of the NRMs and MMCs were analyzed by microscopy techniques and the effects of adding a reinforcing phase to the matrices are reported and linked to their EC resistance. The EC resistance was assessed at different sand contents (10 and 50 g/l) and temperatures (20 and 65 °C) using a submerged impinging jet (SIJ) apparatus; the MMCs were also studied under EC at 5, 10 and 14 m/s to analyze the structural integrity of the reinforcing phase. The results shown that, the C Ni was the more EC resistant coating under most of the experimental conditions, at 5 m/s the EC degradation mechanism was dominated by matrix degradation with the WC showing little damage and the C Fe was negatively affected by corrosion, especially at 65 °C. Interestingly, the MMCs were more susceptible to changes in temperature whereas, for the NRMs EC resistance was more affected by the sand content of the slurry.

ChemInform Abstract: A Supersonic Molecular Jet for a Fourier Transform Interferometer: The ν3 Band of OCCCO.

Abstract A supersonic molecular jet apparatus has been constructed for use with a Fourier transform infrared spectrometer (Bruker IFS 120 HR) or with the millimeter-wave and diode laser spectrometers available in the Giessen laboratory. Design criteria were chosen to provide optimum conditions for obtaining spectral simplification for relatively large molecules with large amplitude motions. Use with unstable species is planned. Thus, throughput could not be too high, and temperature need not be extremely low. First results with the jet system attached to the interferometer are presented. Test measurements with CO2 show a rotational temperature of 22 K for a hole nozzle, and are used to contrast the spectra from a hole and a slit nozzle. A trial jet spectrum of OCCCO shows significant cooling of the low-lying ν7 bending mode and considerable simplification, revealing some new features not detected in an earlier room-temperature study.

Comparison of Inconel 625 and Inconel 600 in resistance to cavitation erosion and jet impingement erosion

Liquid droplet erosion (LDE), which often occurs in bellows made of nickel-based alloys, threatens the security operation of the nuclear power plant. As the candidate materials of the bellows, Inconel 600 and Inconel 625 were both tested for resistance to cavitation erosion (CE) and jet impingement erosion (JIE) through vibratory cavitation equipment and a jet apparatus for erosion-corrosion. Cumulative mass loss vs. exposure time was used to evaluate the erosion rate of the two alloys. The surface and cross-sectional morphologies before and after the erosion tests were observed by scanning electron microscopy (SEM), the inclusions were analyzed by an energy dispersive spectroscopy (EDS), and the surface roughness was also measured by surface roughness tester to illustrate the evolution of erosion process. The results show that the cumulative mass loss of CE of Inconel 625 is about 1/6 that of Inconel 600 and the CE incubation period of the Inconel 625 is 4 times as long as that of the Inconel 600. The micro-morphology evolution of CE process illustrates that the twinning and hardness of the Inconel 625 plays a significant role in CE. In addition, the cumulative mass loss of JIE of Inconel 625 is about 2/3 that of Inconel 600 at impacting angle of 90°, and almost equal to that of the Inconel 600 at impacting angle of 30°. Overall, the resistance to CE and JIE of Inconel 625 is much superior to that of Inconel 600.

Experimental comparison of cavitation erosion rates of different steels used in hydraulic turbines

The prediction of cavitation erosion rates has an important role in order to evaluate the exact life of components in fluid machineries. Hydro-Québec has studied this phenomenon for several years, in particular in hydraulic turbine runners, to try to understand the different degradation mechanisms related to this phenomenon. This paper presents part of this work. In this study, we carried out experimental erosion tests to compare different steels used in actual hydraulic turbine runners (carbon steels, austenitic and martensitic stainless steels) to high strength steels in terms of cavitation erosion resistance. The results for these different classes of steels are presented. The tests have been performed in a cavitating liquid jet apparatus according to the ASTM G134-95 standard to simulate the flow conditions. The mass loss has been followed during the exposure time. The maximum depth of erosion, the mean depth of erosion, and the mean depth erosion rate are determined. As a result we found that ASTM-A514 high strength steels present excellent cavitation erosion resistance properties. The cavitation eroded surface is followed by optical profilometry technique. Determination of mechanical properties and examinations of the eroded surfaces of the samples have also been carried out in order to identify the erosion mechanisms involved in the degradation of these kinds of materials.

Prediction method for cavitation erosion based on measurement of bubble collapse impact loads

The prediction of cavitation erosion rates is important in order to evaluate the approximate life of components in fluid machinery. The measurement of impact loads in bubble collapses helps us to predict the life under cavitation erosion. In this study, we carried out the erosion tests and measured impact loads in bubble collapses with a cavitating liquid jet apparatus which complies with the ASTM G134-95 standard. The bubble collapse impact loads were measured by a piezo ceramic transducer in a cavitating liquid jet apparatus. To produce various cavitation conditions, the flow velocity was changed from 184 down to 80 m/s. We evaluated the incubation period based on a cumulative damage rule by measuring the impact loads of cavitation acting on the specimen surface and using the “constant impact load – number of impact curve” similar to the modified Miner's rule which is employed for fatigue life prediction. We found that the parameter ∑(Fiα×ni) (Fi: impact load, ni: number of impacts and α: constant) is suitable for the evaluation of the erosion life. After the constant α has been obtained under two different cavitation conditions, we can predict the incubation period with the cavitating liquid jet method under yet another condition, provided that the bubble collapse impact loads are measured.

1D and 2D absorption-rate/kinetic modeling and simulation of carbon dioxide absorption into mixed aqueous solutions of MDEA and PZ in a laminar jet apparatus

The kinetics of the reaction between carbon dioxide (CO 2) and mixed solutions of methyldiethanolamine (MDEA) and piperazine (PZ) was investigated experimentally in a laminar jet apparatus. The experimental kinetic data were obtained under no interfacial turbulence and over a temperature range from 313 to 333 K, MDEA/PZ wt% concentration ratios of 27/3, 24/6 and 21/9, and CO 2 loadings from 0.0095 to 0.33 mol CO 2/mol amine. In addition, a new absorption-rate/kinetics model for the kinetics of the mixed of solvents was developed, which takes into account the coupling between chemical equilibrium, mass transfer, and all possible chemical reactions involved in the CO 2 reaction with MDEA/PZ solvent. The partial differential equations of this model were solved by the finite element numerical method (FEM) based on COMSOL software. The obtained experimental kinetics data were used to obtain the kinetic parameters of CO 2 absorption into MDEA/PZ solutions. The reaction-rate constant obtained for PZ blended with MDEA was kPZ = 2.572 × 10 12 exp(−5211/ T). The 2D model for the blended amines MDEA/PZ has revealed the concentration profiles of all the species in both the radial and axial directions of the laminar jet which has enabled a better understanding of the correct sequence in which the reaction steps involved in the reactive absorption of CO 2 in aqueous mixed MDEA/PZ solution occur. It also revealed that PZ may be depleted by the time the solvent blend of MDEA/PZ with a loading greater than 0.015 mol/mol amine is exposed to CO 2 from the top of the laminar jet absorber.

0414 噴流法による二段環境下のキャビテーション損傷研究(OS4-3 キャビテーションおよびマイクロバブル効果とその応用技術,オーガナイズドセッション)

Two-stage cavitation erosion tests were performed using carbon steel S15C with a cavitating jet apparatus in seawater and tap water. The mass loss of carbon steel S15C by cavitation erosion is reduced remarkably when the test solution is changed to tap water from seawater. However, the mass loss rate that occurs when the experimental environment is changed to seawater from tap water is markedly higher because of corrosive action and mechanical disruption, and their synergistic effects. Changes in the environment demand consideration of the fluid mechanics because mass loss increases remarkably when the environment is changed repeatedly to seawater from tap water.

Kinetics of carbon dioxide absorption into mixed aqueous solutions of MDEA and MEA using a laminar jet apparatus and a numerically solved 2D absorption rate/kinetics model

New comprehensive numerically solved 1D and 2D absorption rate/kinetics models have been developed, for the first time, to interpret the experimental kinetic data obtained with a laminar jet apparatus for the absorption of carbon dioxide (CO 2) in CO 2 loaded mixed solutions of mixed amine system of methyldiethanolamine (MDEA) and monoethanolamine (MEA). Three MDEA/MEA weight ratios ranging from 27/03 to 23/07, over a concentration range of 2.316–1.996 kmol/m 3 for MDEA and of 0.490–1.147 kmol/m 3 for MEA were studied. The models take into account the coupling between chemical equilibrium, mass transfer, and the chemical kinetics of all possible chemical reactions involved in the CO 2 reaction with MDEA/MEA solvent. The partial differential equations of the 1D model were solved by two numerical techniques; the finite difference method (FDM) based on in-house coded Barakat–Clark scheme and the finite element method (FEM) based on COMSOL software. The FEM comprehensive model was then used to solve the set of partial differential equations in the 2D cylindrical coordinate system setting. Both FDM and FEM produced very accurate results for both the 1D and 2D models, which were much better than our previously published simplified model. The reaction rate constant obtained for MEA blended into MDEA at 298–333 K was k MEA = 5.127 × 10 8 exp(−3373.8/ T). In addition, the 2D model, for the first time, has provided the concentration profiles of all the species in both the radial and axial directions of the laminar jet, thereby enabling an understanding of the correct sequence in which the reaction steps involved in the reactive absorption of CO 2 in aqueous mixed amines occur.

Kinetics, modeling, and simulation of the experimental kinetics data of carbon dioxide absorption into mixed aqueous solutions of MDEA and PZ using laminar jet apparatus with a numerically solved absorption-rate/kinetic model

The kinetics of the reaction between carbon dioxide (CO2) and mixed solutions of Methyldiethanolamine (MDEA) and Piperazine (PZ) was investigated experimentally in a laminar jet apparatus. The experimental kinetic data were obtained under no interfacial turbulence and over a temperature range from 313 to 333 K, MDEA/PZ wt% concentration ratio of 27/3, 24/6 and 21/9, and CO2 loading from 0.0095 to 0.33 mole of CO2 per mole of amine. A new comprehensive absorption-rate/kinetics model for mixed solvents was developed, which takes into account the coupling between chemical equilibrium, mass transfer, and the chemical all possible chemical reactions involved in the CO2 reaction with MDEA/PZ solvent. The partial differential equations of this model were solved numerically using the finite element method (FEM) based on COMSOL software. The obtained experimental kinetics data were interpreted with this new developed absorption-rate/kinetics model in order to obtain the kinetics parameters for the CO2 absorption into MDEA/PZ solutions. There was excellent agreement between the experimental and predicted absorption rate values from the 1-D comprehensive kinetics model.

Improving the fatigue strength of the elements of a steel belt for CVT by cavitation shotless peening

The elements of steel belts used for continuously variable transmission (CVT) are subjected to a bending load during operation. The weakest portion of the elements is at the root of the ‘‘neck’’ which works into metallic rings. In order to reduce the stress concentration, the root of the neck is rounded and the shape of element is optimized. Nevertheless, if the fatigue strength of the elements can be improved, the steel belt can be applied to larger engines. Although conventional shot peening is one way of enhancing the fatigue strength, it is very difficult for shot to reach into deep and narrow regions. Recently, a peening method using the impact produced as cavitation bubbles collapse has been developed [1–9]. This method is called ‘‘cavitation shotless peening (CSP)’’, as shot are not required [3–6, 8]. CSP can peen the surface even through deep narrow cavities, as the bubbles can reach these parts and collapse where peening is required. In the present article, improvement of the fatigue strength of the elements of a CVT metallic belt by CSP was demonstrated experimentally. Elements were treated with different processing times and evaluated by a fatigue test to find the optimum processing time. In order to evaluate the peening effect by CSP, the residual stress was measured. Note that this is the first report published on the improvement made in the fatigue strength of a part with regions that cannot be hit directly by shot. Cavitation shotless peening was applied to the element using cavitating jet apparatus, the details of which can be found in references [3–6, 8]. The jet was injected into the neck region through grooves in the elements, which were stacked and held together, and scanned perpendicularly over the elements, as shown in Fig. 1. The processing time per unit length, tp, is defined by the number of scans n and the scanning speed v; tp 1⁄4 n v ð1Þ

Detection of Incipient Cavitationin Cavitating Liquid Jet Apparatus with an Accelerometer and Its Application to Orifice Cavitation

In general, cavitation is an undesirable phenomenon in many cases. In order to prevent from cavitation which produces great damage in the valves and piping system of power plants, it is necessary to detect the occurrence of cavitation. In order to determine the initial stage of cavitation process, an accelerometer was used to establish the technique of estimating the incipient cavitation number by impact signals. On the other hand, in many cases, cavitation number in orifice part is defined with the average flow velocity, however, the definition with upstream and downstream pressure of flow is more useful. Therefore, the incipient cavitation number defined in general way by using a cavitating jet method was clarified and was extended to regular orifice cavitation.

Testing of Carbon Dioxide Corrosion Inhibitor Performance at High Flow Velocities in Jet Impingement Geometry. Effects of Mass Transfer and Flow Forces

Abstract The performance of three continuous treatment carbon dioxide (CO2) corrosion inhibitor products was tested in an impinging jet apparatus (40°C, CO2 partial pressure 1 bar, pH 5, 3 wt% sodium chloride [NaCl] brine). The objective was to test the performance of the inhibitors at very high flow velocities; the jet flow velocity was varied in the range from 0.5 m/s to 20 m/s. Methods for characterization of mass transfer and calculation of wall shear stress are described. To assess how dissolved oxygen (O2) biased the test results, the dissolved oxygen (O2) concentration was intentionally held within two different ranges: 2 ppb to 4 ppb and 8 ppb to 30 ppb. Since flow velocity and O2 concentration were varied independently, a flow-dependent inhibited corrosion rate observed in the higher O2 concentration range could be attributed to flow-dependent O2 corrosion; the corrosion current was close to the O2 diffusion-limited current. The inhibited corrosion rate was not affected by the flow as long as O2 ...

Effect of Additives on Shape Evolution during Electrodeposition: II. Parameter Estimation from Roughness Evolution Experiments

Numerical analysis procedures are used to identify the most sensitive parameters and estimate their values based on experimental measurements and a hypothesized mechanism for the effect of additives on copper electrodeposition. The electrolysis system consists of an acid copper sulfate bath containing accelerator, suppressor, and leveler additives in the range of concentrations typically used for deposition of on-chip wiring interconnections. Experimental measurements, obtained with an impinging jet apparatus, included surface roughness evolution and potential-time curves under constant current deposition in a set of 36 electrolyte compositions, selected by a D-optimal design procedure. The hypothesized additive mechanism consisted of a set of 15 surface reactions and 3 homogeneous chemical reactions. A mathematical model was composed that couples kinetic Monte Carlo simulation (for roughness evolution) with a finite volume method (for computing surface concentrations and potential). After identifying the most sensitive parameters and estimating their values, the surface concentrations of key species associated with the additive mechanism were simulated. The methods reported here are reusable and may be applied to other applications beyond the copper electrodeposition used here for its initial development.

Combinatorial materials research applied to the development of new surface coatings VI: An automated spinning water jet apparatus for the high-throughput characterization of fouling-release marine coatings

Large numbers of coatings can be generated very quickly using a combinatorial high-throughput approach. Rapid screening assays are typically required to adequately evaluate and down select coating candidates to identify promising compositions. An automated, spinning water jet apparatus was developed to rapidly characterize the adhesion strength of marine organisms to coating surfaces. Coating arrays are cast in multiwell plates and subjected to a jet of water of controlled pressure and duration. Array plates are manipulated by a robotic arm to facilitate accurate and repeatable water jet treatments. Jet pressures of 40-688 kPa can be generated and precisely maintained by computer control. A five axis robotic arm selects plates from three plate stacking hotels yielding a total of 39 plates or 936 individual coating samples for each experimental run. All robotic instructions, process parameters, and data are stored and controlled by the computer. The large plate handling capacity offered by the robotic system enables the analysis of a wide variety of coatings for "fouling-release" properties. A brief example demonstrating the capability of the automated water jet apparatus to evaluate marine bacterial adhesion to coating surfaces is provided.