Vapor Jet Research Articles

Three-dimensional simulation of film boiling on a horizontal surface with magnetic field

This study conducts a numerical investigation into the three-dimensional film boiling of liquid under the influence of external magnetic fields. The numerical method incorporates a sharp phase-change model based on the volume-of-fluid approach to track the liquid–vapour interface. Additionally, a consistent and conservative scheme is employed to calculate the induced current densities and electromagnetic forces. We investigate the magnetohydrodynamic effects on film boiling, particularly examining the pattern transition of the vapour bubble and the evolution of heat transfer characteristics, exposed to either a vertical or horizontal magnetic field. In single-mode scenarios, film boiling under a vertical magnetic field displays an isotropic flow structure, forming a columnar vapour jet at higher magnetic field intensities. In contrast, horizontal magnetic fields result in anisotropic flow, creating a two-dimensional vapour sheet as the magnetic strength increases. In multi-mode scenarios, the patterns observed in single-mode film boiling persist, with the interaction of vapour bubbles introducing additional complexity to the magnetohydrodynamic flow. More importantly, our comprehensive analysis reveals how and why distinct boiling effects are generated by various orientations of magnetic fields, which induce directional electromagnetic forces to suppress flow vortices within the cross-sectional plane.

Analysis of the Influence of the Size of Color-Calibrated Schlieren Filters on the General Sensitivity of Quantitative Schlieren Systems

The quantitative color schlieren technique is renowned for its capacity to convert deflection angles into color ratios. This technique has been instrumental in providing data on 2D flows. The current study delves into assessing how the geometry and optical characteristics of color filters impact the sensitivity of the schlieren system. At present, there are many papers making the assumption that implementing a larger-sized color filter leads to better system sensitivity. However, having more calibration filter positions can lead to measurement errors due to the difficult calibration process. The present investigation focuses on the type of color filters created with a gradual evolution of colors. A turbulent, round water vapor jet serves as the test case. By comparing the results obtained with two different filter sizes, this analysis gives insight into the compromises made between system sensitivity and ease of calibration, helping one to better understand the trade-offs between the above-mentioned parameters. Moreover, the quantitative and qualitative results of the test case are presented to offer more comprehensive insights into quantitative color-calibrated schlieren.

Multiresponse optimisation and process capability analysis of chemical vapour jet machining for the acrylonitrile butadiene styrene polymer: Unveiling the morphology

Abstract The implementation of three-dimensional (3D) printing technology has culminated in a notable rise in productivity and operational effectiveness for manufacturers. Additive manufacturing (AM) is a manufacturing technology that implies an alteration from the conventional approach of material removal. The fundamental idea underlying the AM technique is the gradual buildup of layers (layer-on-layer accumulation). In conventional approaches, every component can have detrimental implications due to the direct interaction between the tool and the workpiece, leading to the loss of heat through friction. The utilisation of 3D printing as a way to surpass conventional processing methods signifies a novel development in several sectors. This method involves the utilisation of unconventional techniques for the fabrication of components. The primary objective of this research is to investigate the chemical vapour jet drilling technique specifically applied to acrylonitrile butadiene styrene (ABS) materials. The intent is to enhance the surface characteristics, or surface finish (SF), and the dimensional accuracy (DA) of ABS workpieces. An evaluation regarding the reliability, repeatability, as well as preciseness of the vapour jet drilling (VJD) process is conducted via the utilisation of experiment and data analysis. The study employed a Taguchi L9 design of experiments to carry out a series of tests aimed at analysing the implications of three independent variables: pressure, flow rate, and standoff distance. The researchers employed a multiresponse optimisation approach to attain an optimal combination of parameters that resulted in a superior SF with DA. Consequently, the overall appeal of the outcome was reached. The process’s capabilities and dependability were assessed by conducting tests on the substrates at their optimal settings. Surface roughness and circularity were measured at numerous locations on the substrates. The study determined that the process capability indices (C p and C pk) had values over 1.33 for each of the response parameters, with C pk values also exceeding 1. The analysis of histograms and capability indices demonstrates that the VJD method, when conducted under optimised conditions, may be categorised as statistically controlled for the processing of ABS materials.

Performance assessment of novel catalytic spouted-bed vapor jet flow heat exchanger in amine-based carbon capture process

This study introduced a spouted bed and jet flow catalytic heat exchanger (SBJ-EX). This novel non-agitated technology can potentially integrate with a conventional desorption column to enhance heat transfer and CO2 desorption performance in amine-based post-combustion carbon capture systems. As its first research in the carbon capture field, this work experimentally evaluated key factors including overall heat transfer coefficient, logarithmic mean temperature difference, temperature distribution along the reactor, and cyclic loading under varied parameters such as inlet temperature of the heating oil, inlet solvent temperature, rich CO2 loadings, and mass of catalysts to simulate real-world operating conditions using benchmark MEA solvent and solid acid catalyst HZSM-5. Compared to conventional plate heat exchangers, the SBJ-EX demonstrated over a 70 % enhancement in heat transfer performance due to its effective overall heat transfer coefficient. It also exhibited impressive CO2 desorption performance even at lower temperatures with sufficient catalysts. Unlike agitated-type heat exchangers, the SBJ-EX could minimize catalyst attrition and offer more excellent stability. In contrast to fixed-bed catalyst desorbed columns, this equipment offered a more compact design for quicker and simpler catalyst replacement to reduce downtime for operators significantly. The SBJ-EX can also function as an optional backup or add-on unit to provide operators with flexibility. This work further discussed advantages and challenges of the SBJ-EX operation. This work enriched the future research outlook for this technology, and contributed a commercially viable approach to catalysts in carbon capture processes.

A regionally refined quarter-degree global atmospheric rivers database based on ERA5

Atmospheric rivers (ARs) are narrow, elongated, synoptic jets of water vapor that play important roles in the global water cycle. The continually developing Tracking Atmospheric Rivers Globally as Elongated Targets (tARget) algorithm identifies AR objects at individual time steps based on thresholding integrated water vapor transport (IVT) and other requirements, and tracks each AR object in time and space. Building on previous versions of tARget, this paper discusses further refinements to the algorithm to better handle ARs in tropical and polar areas, as well as “zonal” ARs which the previous versions of the algorithm were not designed to capture. This further regionally refined algorithm is applied to the ERA5 reanalysis over 1940–2023 at 6 h intervals and a 0.25° × 0.25° horizontal resolution. The AR detection results are evaluated in terms of key AR characteristics. We anticipate this regionally refined global AR database will aid further understanding of ARs such as AR process studies, evaluation of AR simulations and predictions, and assessment of climate change impacts on ARs.

The identification of airbursts in the past: Insights from the BIT-58 layer

Airbursts are estimated to be the most frequent type ofdestructive impact events. Yet, confirmation of these events is elusive, resulting in a major gap in the impact record of Earth. The recent discovery of igneous chondritic spherules produced during a new type of touchdown airburst 430 thousand years (kyr) ago over Antarctica, in which a projectile vapor jet interacts with the Antarctic ice sheet, provided the first trace of such an impact in the geological record. In terms of petrology and geochemistry, particles constituting the BIT-58 dust horizon, which was found in surface ice at near Allan Hills in Antarctica, are almost identical to those produced 430 kyr ago. We demonstrate here that BIT-58 particles were indeed formed during a touchdown event between 2.3 and 2.7 million years (Myr) ago. This represents the oldest record of an airburst on Earth identified to date. Slight geochemical differences with 430 kyr old airburst spherules provide additional constraints on spherule condensation in large airburst plumes. Finding confirmation of airbursts in the paleorecord can provide insight into the frequency of the most hazardous impacts and, thus, has implications for planetary defence.

Study of the combustion process of liquid off-design fuel in a spray burner device with a controlled supply of primary air

This work studies the process of combustion of liquid off-design fuel (using waste oil as an example) in a jet of superheated water vapor in a spray burner device with a controlled supply of primary air. The average temperature along the vertical axis of the burner device was measured, the composition of intermediate and final combustion products, and heat release were studied when the parameters in the gas generation chamber were varied. It has been shown that changing the primary air flow rate when spraying liquid off-design fuel with a jet of superheated water vapor can additionally influence the flame structure and the level of emissions. And the technology itself can be used to create low-emission burner devices.

Investigating impact of zinc vapor jet on keyhole dynamics and liquid ejection from molten pool during remote laser welding of zinc-coated steel in zero-gap lap joint configuration

When Zn-coated steels are laser welded in a zero part-to-part gap lap joint configuration, highly pressurised Zn vapors are readily produced, generating spatters in the weld. The best practice is to set a non-zero gap to facilitate vapor degassing; however, this necessitates additional operations, escalating production costs. This paper aims to investigate the keyhole dynamics and the ejections from the molten pool due to the interaction between high-pressure Zn vapors and the liquid metal, during remote laser welding of Zn-coated DX57D+Z steel sheets at zero nominal part-to-part gap in lap joint configuration. This is achieved by complementing experimental trials with multi-physics Computational Fluid Dynamics (CFD) simulations. The findings showed that the interplay between heat-affected zone, Zn evaporation zone, size/shape of the laser beam are critical factors for controlling the effect of Zn vapors jet on keyhole stability and liquid ejections. Opportunities for laser beam shaping are discussed throughout the paper.

Experimental and Numerical Investigation of Expanding Mercury Vapor Jets

Experimental and Numerical Investigation of Expanding Mercury Vapor Jets

Bioinspired superhydrophobic light-driven actuators via in situ growth of copper sulfide nanoparticle on cellulose nanofiber

Among stimuli-responsive actuators, light-driven hydroplaning actuators have attracted significant attention because of their controllable and contactless nature. However, manufacturing actuators with rapid dynamic responses to a single stimulus remains challenging. Herein, inspired by rove beetles and water striders, we developed superhydrophobic light-driven actuators based on the in situ growth of copper sulfide on cellulose nanofiber and subsequent modification with octadecyltrimethoxysilane. The actuators exhibited excellent superhydrophobicity (water contact angle of 160.6°) and the water contact angle was maintained above 150° under various harsh conditions (acid/base immersion, ultraviolet irradiation, heat treatment, and sandpaper abrasion). Under near-infrared (NIR) irradiation (808 nm, 1.4 W cm−2), excellent photothermal performance was achieved, with a photothermal-induced temperature change of 81.0 °C. Based on the mechanisms of superhydrophobicity, the Marangoni effect, and vapor jet flow, the light-driven actuators exhibited a rapid dynamic response (response time of 0.5 ± 0.2 s), ensuring fast linear motion (velocity of 8.7 ± 0.7 mm s−1) and flexible rotation (angular speed of 2.4 rad s−1) under NIR irradiation. Moreover, complex motions such as S-shaped, triangular, and circular motions were achieved by combining linear motion and rotation, which could facilitate obstacle avoidance, smart transportation, and contactless delivery.

Influence of the laser-induced plume on welding behavior in keyhole welding for stainless steel using a 16 kW disk laser

The spatter is one of the defect factors for laser welding. For high-quality laser welding, the elucidation of the spatter reduction mechanism is required. In our previous study, it was elucidated that the molten pool and keyhole fluctuation contribute to spatter generation from the observation of the keyhole and molten pool under different ambient pressure conditions. However, the main cause of the instability of the molten pool and keyhole has not been clarified. It is considered that the interaction between the laser and plume might cause these instabilities. Therefore, in this study, we focused on the plume generated by laser irradiation. The dynamics of the plume during laser welding and the attenuation of the laser were observed under different ambient pressures. According to these observations, the effect of the plume on instability in laser welding was elucidated. The SS304 was fixed in the vacuum chamber, and the disk laser with an output power of 6 kW swept on the sample to form the weld bead. At the same time, the plume behavior was observed by the Schlieren method, and the attenuation of the laser was measured using a probe laser. As a result, the metal vapor jet, which is a periodical plume ejection, was observed. The attenuation of the probe laser increased with increasing atmospheric pressure. These results suggest that the frequent generation of the metal vapor jet under atmospheric pressure caused instability in the heat input of the laser, which caused instability in the keyhole and molten pool.

Experimental study of interface behavior and sound pressure oscillation of direct contact condensation of a steam jet in flowing water

Direct contact condensation of a vapor jet in liquid is frequently encountered in lots of industrial applications because of its high heat and mass transfer rates. However, severe interface and sound pressure oscillation associated with condensation might cause vibration and even failure of pipeline systems. In this paper, the interface behavior and the sound pressure oscillation of a steam jet in flowing water are captured respectively by a high-speed camera and a high-frequency hydrophone. According to the gray profile of the image, an identification method is proposed to determine the interface characteristics, including the plume shape, width, and penetration length of the jet. The statistical intensity and power spectrum density of the interface position and sound pressure oscillation of the steam jet are calculated. Two typical condensation regimes of Chugging and Oscillation-I under low steam mass flux (Gs < 346 kg/m2s) are observed. The intensities of the interface oscillation and sound pressure oscillation decline with increasing steam mass flux and a significant correlation coefficient of about 0.94 between them is revealed. With the incorporation of sound pressure parameters, two correlations of the dimensionless jet length and its oscillation intensity are established, with relative deviations of 20% between the experimental and predicted values. For Oscillation-I, the dominant frequencies of the interface oscillation and sound pressure oscillation are quantitatively consistent. From the time and frequency domain perspectives, it is quantitatively confirmed that the sound pressure oscillation of the steam jet under low steam mass flux is caused by its interface oscillation.

Impact of spring Tibetan Plateau snow cover on extreme precipitation in Pakistan in July and August 2022

Record-breaking extreme precipitation occurred in July and August 2022 in Pakistan, causing flooding and landslides. In this study, the characteristics and mechanisms of these extreme precipitation events are investigated. The consecutive extreme precipitation events emerged in July and mid to late August. Precipitation above 500 mm occurred in the northern and southern regions of Pakistan, and the maximum precipitation was concentrated in the same regions. The diagnosis indicated that the precipitation extremes were closely tied to anomalous late spring snow cover in the western Tibetan Plateau. In July, owing to the reduction of late spring snow cover, the strengthened diabatic heating promoted the South Asian High (SAH) and its pumping effect, which contributed to abundant water vapor and strong southeasterly jet along the southwest Tibetan Plateau. Cooperating with the cyclone over Arabian Sea, extreme precipitation with a return period of 50 years occurred in Pakistan. In August, the SAH was an anomalously strong and eastward extension at 200 hPa. In the middle troposphere, the blocking high-pressure over western Russia was extremely active, and the West Pacific Subtropical High shifted anomalously westward, extending to the Tibetan Plateau. Cyclone anomalies occurred over the Arabian Sea and Bay of Bengal. With the atmospheric circulation anomaly, the southeasterly jet shifted southward, and water vapor was transported from the Arabian Sea and Bay of Bengal to south Pakistan, causing extreme precipitation with a return period of 30 years in August.

Arsenic Vapor Condensation in the Vacuum-Thermal Dearsenation Process of Gold Concentrate

ABSTRACT Our study investigates the condensation mechanism of vapors containing arsenic, with a particular focus on the conditions required for the creation of melted and dispersed sulfide condensate that have practical implications in technological processes. Our findings indicate that at vapor jet efflux under low pressure, ultrafine particles generates in the condensation space at first. Then they are precipitated on the cooled walls of the condenser. We explored the transition of arsenic sulfide vapor into the liquid phase and noted a simultaneous occurrence of the crystalline and liquid condensates. Our findings will provide valuable guidance for designing and operating industrial processes for gold-bearing concentrate dearsenation in a vacuum, with the potential for improved safety and efficiency.

Study of the Effective Torus Exhaust High Vacuum Pumping System Performance in the Inner Tritium Plant Loop of EU-DEMO

The requirement for a reduction of the tritium inventory of the European demonstration fusion reactor (EU-DEMO) has led to the active research and development of a continuously working pumping process termed “KALPUREX.” This process foresees the direct recycling of a large fraction of the unburnt hydrogen isotopologues via superpermeation in metal foil pumps during the burn phase. The remaining exhaust gas mixture is pumped by continuously operating, mercury-driven linear diffusion pumps. Diffusion pumps are kinetic high vacuum pumps whose pumping principle is based on the momentum transfer from a supersonic mercury vapor jet to the pumped gas mixture. Like many high vacuum pumps, they feature species-dependent pumping speeds. In the present work, we develop a simplified hybrid model of the high vacuum pumping train in order to estimate the effective pumping speed of the integrated system. The results of this model and its implications on the further development of the vacuum system are discussed for the burn and dwell phases of EU-DEMO.

Influence of Oxygen Concentration in Building Environment and Oxidation Extent of Maraging Steel on Spatter Generation Behavior in Powder Bed Fusion

This study investigated the influence of oxygen concentration in the building environment and the degree of oxidation of maraging steel powder on spatter generation behavior during powder bed fusion (PBF) process. The powders were oxidized at various heat treatment temperatures, and their degree of oxidation was evaluated using Auger electron spectroscopy. The spatter generation behavior of the powders at oxygen concentrations of 1.0×102 ppm (99.99% purity) to 5.0×104 ppm (95% purity) in the building atmosphere was then investigated. The results indicated that the presence of oxygen in the building environment had a greater effect on spatter generation than the oxide film on the maraging steel powder. The oxygen concentration affected the velocity and angle of spatter particles. At an oxygen concentration of 5.0×104 ppm, the number of spatter particles was 2.5 times greater than that of 1.0×102 ppm. A higher oxygen concentration resulted in an increase in the number of fume particles adhering to the spatter surface, reducing its reusability. The oxide film on the powder did not significantly affect the vapor jet behavior, but it altered the powder’s flowability, impacting the spatter generation. To decrease spatter generation and obtain a high-quality spatter surface, it is recommended that the oxygen concentration in the building environment should be maintained at 1.0×102 ppm.

Experimental studies of droplet nucleate boiling characteristics on micro-cavities surfaces with different wettability

In this study, micro-cavities surfaces with different wettability are prepared by combining nanosecond laser micro-nano processing technology, chemical oxidation and electrochemical corrosion. The effects of micro-cavities and surface wettability on evaporation time and bubble dynamics are experimentally investigated. The results show that micro-cavities surfaces with smooth structures exhibit excellent evaporation performance as micro-cavity serves as the nucleation site for bubble. The existence of CuO film on micro-cavities surfaces with superhydrophilic structures increases the thermal resistance and hinders the bubble growth, which causes poor droplet evaporation process. On the other hand, the Rayleigh-Taylor instability is easily triggered on micro-cavities surfaces with superhydrophobic structures due to lower surface tension of the solid–liquid interface. This phenomenon causes the strong fluctuation and prolongs the evaporation process. The vapor jet or fluctuating liquid–air interface is observed at the droplet center from the thermal pattern of micro-cavities surfaces with smooth structures. On micro-cavities surfaces with superhydrophilic structures, the fluid at the top of droplet has an obvious temperature gradient due to the existence of vapor bubble. However, strong fluctuation is developed on micro-cavities surfaces with superhydrophobic structures, leading to the fact that the fluid near the liquid–air interface is cooled. Entrapped air inside the micro-cavities serves as the bubble seed for micro-cavities surfaces with smooth structures and micro-cavities surfaces with superhydrophobic structures, thus shortening the time for bubble nucleation.

A Light‐Driven Actuator Enables Versatile Motion for Smart Transportation and Contactless Delivery

AbstractLight‐driven actuators are advantageous among various actuators because it enables remote, contactless, and localized manipulation without any complex equipment. However, most of them rely solely on the Marangoni effect which is slow in velocity and would be quenched in liquid with low surface tension force. Here, a dual‐mode actuator based on both the Marangoni effect and vapor jet flow is reported through the introduction of an excellent photothermal polymer crosslinked by Fe3+/catechol coordination bonds. The light‐driven ship not only realizes multimode motions such as forward, backward, rotation and obstacle crossing at the air/water interface, but also enables smart transportation and contactless delivery which has not been realized before. Moreover, the incorporation of photothermal conversion performance and self‐healing ability into near‐infrared photo‐responsive actuators at the molecular level can guarantee facile fabrication and prolong the service time of the light‐driven actuators which is the first dual‐mode light‐driven actuator with self‐healing ability. This work provides a new strategy for the structural design and application of the liquid/air interface light‐driven self‐propelled device.

Capillary Jet Loop performance in parabolic flight

• a novel two-phase heat transfer device is tested with a parabolic flight campaign. • the performances are tested in different orientations, power and gravity level. • the Capillary Jet Loop working fluid is R1233zde. • microgravity and hypergravity results show dryout instabilities at zero gravity. • Ejector’s By-Pass Ratio is increased in the vertical orientation. In this study, a prototype Capillary Jet Loop Heat Pipe partially filled with R1233zd(E) has been tested to investigate its thermal behaviour on board of parabolic flights where gravity condition changes in the range from 0 to 1.8 g level with a 22 s window of microgravity. The device has been tested both in horizontal and vertical orientations, varying the thermal load provided to the evaporator from 40 W to 180 W. With power higher than 100 W, the device operated in stationary conditions during hypergravity and normal gravity periods. During the microgravity periods, the device has always shown a sharp increase in pressure and temperatures, reducing temporarily the transport capability of the CJL and fast recovery when gravity increases again. Each series of power level results is presented and discussed in terms of temperature, pressure, and temperature difference from the saturation temperature. The thermal power dissipated by the condenser and an estimation of the condensing flow rate have been calculated from the condenser cooling water inlet and outlet to highlight the Capillary Jet Loop operating phenomena. The temperature of the ejector's primary, secondary, and mixing flows (vapour jet pump) are compared for both configurations.

Connection a vapor jet refrigeration system to a steam injected gas turbine

One of the problems with the gas turbine is the reduction of output power and thermal efficiency with an increase in the ambient temperature. This problem is serious, especially in hot and dry areas. To solve this problem, in this study, the connection of the steam jet refrigeration (VJRS) unit to a gas turbine is investigated. By designing a VJRS as an open cycle in this connection, in addition to cooling the inlet air, it is also possible to inject steam into the turbine as a steam-injected gas turbine (STIG) system. So in this process reducing the compressor power consumption and increasing the turbine output power are done simultaneously. With the possibility of injecting most of the steam into the turbine, in addition to the possibility of removing the condenser in the VJRS, the need for cooling water is also eliminated in this process. Therefore, by using a saltwater source to generate steam using the waste heat of the gas turbine, it is possible to increase its output power without the consumption of fresh water. Also compared to a combined cycle, is shown the ability of this process to increase the output power without needing to install additional expensive equipment.