Search Results (25)

The coordinated operation of multiple jet devices enhances the efficiency of technological processes and thrust vector control systems, enabling the resolution of various practical challenges. Traditional jet control systems regulate the thrust vector in the direction from +20° to −20° in a 3D space. For the first time, this study considers, from a general perspective, the conditions under which the thrust vector angle can vary from +180° to −180° in any direction within a complete geometric sphere, including thrust reversal. Conceptual design using computational fluid dynamics (CFD) techniques considers kinematic schemes with variable lengths and flexible links. This study demonstrates the technical feasibility of controlled energy distribution through multidirectional ejector channels, including the maintenance of constant pressure at the nozzle apparatus inlet. Potential modernization strategies for the Laval nozzle incorporating a rotary diffuser were examined. The research outcomes are patented and aimed at developing a digital twin of the jet system for training artificial intelligence based on the philosophy of science and technology and Euler’s methodology within interdisciplinary works. The findings are primarily applicable to research and development efforts focused on creating energy-efficient oil and gas production systems. Furthermore, the research results can be applied to the development of advanced maneuverable unmanned vehicles and robotics for various purposes. Full article

Transport electrification is essential for reducing CO₂ emissions, and technologies such as hybrid and range-extended electric vehicles will play a crucial transitional role. Such vehicles employ an internal combustion engine for on-board chemical energy conversion. The Wankel rotary engine should be an excellent candidate for this purpose, offering a high power-to-weight ratio, simplicity, compactness, perfect balance, and low cost. Until recently, however, it has not been in production in the automotive market, due, in part, to relatively low combustion efficiency and high fuel consumption and unburnt hydrocarbon emissions, which can be traced to constraints on flame speed, an elongated combustion chamber, and relatively low compression ratios. This work used large eddy simulations to study the in-chamber flow in a peripherally ported 225cc Wankel rotary engine, providing insight into these limitations. Flow structures created during the intake phase play a key role in turbulence production but the presence of the pinch point inherent to Wankel engine combustion chambers inhibits flame propagation. Two efficiency-enhancement technologies are introduced as disruptive solutions: (i) pre-chamber jet ignition and (ii) a two-stage rotary engine. These concepts overcome the traditional efficiency limitations and show that the Wankel rotary engine design can be further enhanced for its role as a range extender in electrified vehicles. Full article

The exploration and development of new hydrocarbon deposits is facing increasing challenges as the global shift to renewable energy sources, such as shallow geothermal deposits, wind farms, and photovoltaics, reduces the dependence on hydrocarbons. To navigate this evolving landscape, it becomes crucial to find solutions that optimize the energy extraction efficiency while maximizing the use of hydrocarbon deposits. This requires exploring opportunities in existing fields and wells, including those slated for decommissioning. This article discusses the potential for extracting resources from seemingly depleted fields, where some 60–70% of the resources remain unrecoverable due to low reservoir energy. Meeting this challenge requires the implementation of secondary and tertiary EOR methods that involve the introduction of external energy to increase reservoir pressure and enhance resource recovery. One of the proposed innovative tertiary methods involves reaming the reservoir using multiple small-diameter radial boreholes generated by a hydraulic drilling nozzle. This strategy is designed to intensify the contact between the production hole and the reservoir layer, resulting in increased or commenced production in certain cases. The described method proves to be a practical application in hydrocarbon deposits, offering the dual benefits of mitigating environmental pollution by eliminating the need for drilling new boreholes and providing a cost-effective means of accessing resources in decommissioned deposits with insufficient reservoir energy for self-exploitation. Another article points out the design variation of a hydraulic drilling nozzle tailored specifically for reaming a reservoir layer. Taking the above into account, this article provides very practical information for future projects in which paths should be sought for the design and development of hydraulic wellheads, among other things, in order to intensify the production from hydrocarbon deposits. Full article

Droplet impact angle and shear stress are important indicators of surface runoff under sprinkler irrigation, and determining the distribution characteristics of these two indicators on sloping land is of great significance for preventing soil surface erosion. Therefore, three slopes (0, 10%, and 20%) and two directions (uphill and downhill) under a Rainbird LF1200 rotary sprinkler were considered in this study. The distribution of droplet impact angles and shear stresses along the radial direction were investigated under various working conditions. The correlations among the droplet impact angle, shear stress, and distance from the sprinkler were also analyzed. These results indicated that the closer to the sprinkler, the larger the droplet impact angle and the smaller the shear stress, and the two indicators gradually decreased and increased with the increase of distance from the sprinkler, respectively. Accordingly, there was a very high potential for soil surface runoff at the spray jet end. It was also observed that the uphill direction generally had a greater impact angle and less shear stress than flat land, while the downhill direction had exactly the opposite result. However, regardless of the direction, an increase in the slope could intensify its effect on the droplet shear stress and impact angle. Therefore, there is an urgent need to focus on the occurrence of surface runoff in soils with larger slopes. In addition, two radial droplet shear stress distribution models were developed, and it was verified that Model 2 had higher accuracy (MAE = 176.6 N m⁻², MBE = 32.8 N m⁻², and NRMSE = 14.4%) and could be used to predict the average droplet shear stresses at different slopes, directions, and distances from the sprinkler. This study contributes to the soil erosion prevention and the sprinkler irrigation system optimization on sloping land. Full article

The exploration and development of new hydrocarbon deposits face increasing challenges, primarily driven by the shift away from hydrocarbons towards renewable energy sources like shallow geothermal deposits, wind farms, and photovoltaics. This shift necessitates finding solutions that minimize environmental impact and enable increased energy extraction from existing or decommissioned fields and wells. This paper explores the possibility of excavating from potentially depleted fields, where a significant portion (up to 85%) of the reservoir’s resources remain unrecoverable due to low reservoir energy. To address this, secondary and tertiary exploitation methods are proposed involving the supply of external energy to increase the pressure in the reservoir layer, thereby enhancing resource exploitation. One of the suggested tertiary methods involves reaming the deposit with multiple small-diameter radial holes using a hydraulic drilling nozzle. The entire process comprises several key components, including the coiled tubing unit (CTU), high-pressure flexible hose, window drilling kit for casing pipe, kit for positioning the exit of the hydraulic drilling head from the casing pipe, anchor, and hydraulic drilling head attached to the end of the high-pressure flexible hose. This method aims to increase the contact between the reservoir layer and the wellbore, potentially leading to an increase in or initiation of exploitation in certain deposit scenarios. The described method presents an environmentally friendly approach, eliminating the need for drilling new boreholes and offering cost-effective access to resources in decommissioned deposits with insufficient reservoir energy for self-exploitation. The applicability of this method to extract methane from coalbed seams is also mentioned in this article. In a separate article, the authors detail the design of a hydraulic drilling nozzle specifically for reaming the reservoir layer. Full article

Tissue engineering is vital in treating injuries and restoring damaged tissues, aiming to accelerate regeneration and optimize the complex healing process. In this study, multizonal scaffolds, designed to mimic tissues with bilayer architecture, were prepared using the rotary jet spinning technique (RJS scaffolds). Polycaprolactone and different concentrations of alginate hydrogel (2, 4, and 6% m/v) were used. The materials were swollen in pracaxi vegetable oil (PO) (Pentaclethra macroloba) and evaluated in terms of surface morphology, wettability, functional groups, thermal behavior, crystallinity, and cytotoxicity. X-ray diffraction (XRD) showed the disappearance of the diffraction peak 2θ = 31.5° for samples from the polycaprolactone/pracaxi/alginate (PCLOA) group, suggesting a reduction of crystallinity according to the presence of PO and semi-crystalline structure. Wettability gradients (0 to 80.91°) were observed according to the deposition layer and hydrogel content. Pore diameters varied between 9.27 μm and 37.57 μm. Molecular interactions with the constituents of the formulation were observed via infrared spectra with Fourier transform (FTIR), and their influence was detected in the reduction of the maximum degradation temperature within the groups of scaffolds (polycaprolactone/alginate (PCLA) and PCLOA) about the control. In vitro tests indicated reduced cell viability in the presence of alginate hydrogel and PO, respectively. Full article

In order to ensure the safety and stability of the existing old masonry structure houses in the process of dewatering and excavation of the super deep foundation pit of the subway, the support form of a water stop curtain combined with bored cast-in-place piles and internal support is adopted, and the rotary jet grouting piles are constructed around the houses, and sleeve valve pipes are embedded, and the soil and house foundation are grouted and strengthened. The deformation of the building foundation is analyzed by the finite element method. The results show that the deformation of adjacent buildings is mainly uniform at the initial stage of foundation pit dewatering and excavation. With the increase of foundation pit dewatering and excavation depth, the deformation of adjacent buildings shows significant differential characteristics, and the maximum displacement of buildings is settlement deformation. The field monitoring data show that the actual deformation trend and value range of the building structure are basically consistent with the finite element calculation results, and no new damage is found in the building structure during the construction process. Effective foundation pit support method and soil layer reinforcement method can effectively reduce the impact of foundation pit on the deformation of adjacent buildings. Full article

The developed karst caves may become the seepage channels of heavy metal to the soil and underground water in Southwest China. Therefore, it is necessary to apply effective seepage treatments to the base of heavy metal tailing reservoirs. This paper addressed the high-pressure rotary jet technology and slurry systems used in the seepage treatment of the deep tailing sand of the Shenxiandong tailing pond located in Southwest China. In this study, the factors of fluidity, initial and final setting times, compressive strength, and permeability coefficient of the slurry were conducted. The mechanism analysis was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and inductively coupled plasma-mass spectrometry (ICP-MS). Three different types of slurry systems were proposed, and the permeability coefficients of the solidification body following 28 days of curing were less than 1 × 10⁻⁷ cm/s. The concentrations of Pb and Zn in the slurry system containing bentonite were reduced by 26.2% and 45.7%, respectively. In the presence of slaked lime and fly ash, the concentrations of Pb and Zn could be reduced by 26.8% and 30%, respectively. A total of 2142 high-pressure rotary jet piles were completed by the high-pressure rotary jet method in the field trial. The diffusion radius of these piles was over 1 m. Following 28 days of curing, the solidification body’s compressive strength was 7.45 MPa and the permeability coefficient was 6.27 × 10⁻⁸ cm/s. Both the laboratory and on-site trials showed that this method produced a good pollution barrier effect, which could prevent the diffusion of heavy metal into the adjacent underground water through the karst caves. It is also an effective way of engineering technology concerning heavy metal pollution control that occurs in tailing ponds. Full article

In order to solve the problem that digging lotus roots manually was high in labor intensity, low in efficiency and easy to damage lotus roots, and, in view of the defects of the high cost of existing digging lotus roots equipment and the cumbersome operating process needing a certain experience in technology, a jetting spin type digging lotus root machine is designed. Combined with the mechanism of hydraulic digging lotus root, a rotation pipeline is designed, so as to simplify the whole machine structure and increase the digging width. It takes only manpower or vehicles to push forward to perform digging lotus root work, with simple operation and low manufacturing cost. Pro/Engineer 3D design software and CAD 2D drawing software are used to design key working parts such as rotation pipeline, spray-head, nozzle, etc. In addition, key parameters of nozzle structure are designed. Through validation, the intensity of jet flow impact force produced by the diameter 17 mm nozzle to lotus root surface is 97.22 N, and the pressure is 0.20 MPa, which produces no damage to lotus root. By means of a mechanical analysis method, combined with CFD flow field analysis and fluid dynamics analysis, the rotational speed mathematical model of rotation pipeline in water is established through MATLAB software solving and calculating. In addition, the influence of nozzle structural parameters on rotational speed of rotation pipeline is made clear. By using the kinematic analysis method, the rotational speed mathematical model of rotation pipeline associated with the jetting impact frequency of single point and the time of each impact is established, and from which the restricting factors of the working speed of jetting spin type digging lotus root machine is obtained, so as to improve the efficiency of digging lotus roots machine under the premise of ensuring the digging depth and the quality of lotus roots. Through the CFD flow field analysis and dynamic analysis, the mathematical model of loss power of rotating pipeline is established. Through comprehensive analysis, the mathematical model of working speed associated with digging time and speed of rotary pipe and effective range radius of jet impact for digging lotus root machine is obtained, which provides a theoretical basis for adjustment of working parameters of digging lotus root machine. Full article

The deformation control effect of loess tunnel composite foundation plays an important role in optimization design and reinforcement effect evaluation. Systematically evaluate the adaptability of the composite foundation of jet grouting pile in shallow collapsible loess tunnel. Taking the shallow buried section of Fujiyao Tunnel with a buried depth of 20 m as an example, using MIDAS finite element numerical simulation software, the foundation deformation control during construction and settlement control after construction are systematically studied, the differential deformation control is analyzed, and the reinforcement effect of the tunnel bottom is evaluated. The results show that the uplift displacement can be controlled by changing the pile length and increasing the replacement ratio. The combination of long and short piles can significantly reduce the uneven settlement and plastic zone of the foundation. The uneven settlement of 9 mm can be used as the evaluation index of the composite foundation reinforcement effect in a shallow buried section of the loess tunnel. Full article

No alternatives are currently available to operate industrial furnaces, except for hydrocarbon fuels. Plant managers, therefore, face at least two challenges. First, environmental legislation demands emission reduction. Second, changes in the origin of the fuel might cause unforeseen changes in the heat release. This paper develops the hypothesis for the detailed control of the combustion process using computational fluid dynamic models. A full-scale mock-up of a rotary cement kiln is selected as a case study. The kiln is fired by the non-premixed combustion of Dutch natural gas. The gas is injected at Mach $0.6$ via a multi-nozzle burner located at the outlet of an axially mounted fuel pipe. The preheated combustion air is fed in (co-flow) through a rectangular inlet situated above the attachment of the fuel pipe. The multi-jet nozzle burner enhances the entrainment of the air in the fuel jet. A diffusion flame is formed by thin reaction zones where the fuel and oxidizer meet. The heat formed is transported through the freeboard, mainly via radiation in a participating medium. This turbulent combustion process is modeled using unsteady Favre-averaged compressible Navier–Stokes equations. The standard k-$ϵ$ equations and standard wall functions close the turbulent flow description. The eddy dissipation concept model is used to describe the combustion process. Here, only the presence of methane in the composition of the fuel is accounted for. Furthermore, the single-step reaction mechanism is chosen. The heat released radiates throughout the freeboard space. This process is described using a P1-radiation model with a constant thermal absorption coefficient. The flow, combustion, and radiative heat transfer are solved numerically using the OpenFoam simulation software. The equations for flow, combustion, and radiant heat transfer are discretized on a mesh locally refined near the burner outlet and solved numerically using the OpenFoam simulation software. The main results are as follows. The meticulously crafted mesh combined with the outlet condition that avoids pressure reflections cause the solver to converge in a stable manner. Predictions for velocity, pressure, temperature, and species distribution are now closer to manufacturing conditions. Computed temperate and species values are key to deducing the flame length and shape. The radiative heat flux to the wall peaks at the tip of the flame. This should allow us to measure the flame length indirectly from exterior wall temperature values. The amount of thermal nitric oxide formed in the flame is quantified. The main implication of this study is that the numerical model developed in this paper reveals valuable information on the combustion process in the kiln that otherwise would not be available. This information can be used to increase fuel efficiency, reduce spurious peak temperatures, and reduce pollutant emissions. The impact of the unsteady nature of the flow on the chemical species concentration and temperature distribution is illustrated in an accompanying video. Full article

In China, sandstone geothermal reservoirs are large in scale and widely distributed, but their exploitation is hindered by low recharge efficiency. In this paper, an unblocking and permeability enhancement technology using a rotary water jet for low recharge efficiency wells in sandstone geothermal reservoirs is proposed to solve this problem. This paper presents a series of studies about the proposed technology, including experiments, simulation and field application. Firstly, an experiment was carried out to verify the scale removal effect of a high-pressure water jet on the inner wall of the screen tube and its impact on sandstone. Secondly, the numerical models of the rotary jet flow field in the wellbore were established by ANSYS Fluent to study the influence of parameters. Finally, based on the simulation and experiment results, a rotary jet tool applicable to unblocking and descaling low-efficiency wells was designed, and a field application for low-efficiency wells in sandstone thermal reservoirs was conducted. The study results show that the unblocking and permeability enhancement technology using a rotary water jet is effective in removing the blockages and improving the permeability near the well. In conclusion, the presented technology can solve the problem of low efficiency during the reinjection of cooled thermal waters back into sandstone geothermal reservoirs and has great effectiveness in field application. Full article

Wounds result from different causes (e.g., trauma, surgeries, and diabetic ulcers), requiring even extended periods of intensive care for healing, according to the patient’s organism and treatment. Currently, wound dressings generated by polymeric fibers at micro and nanometric scales are promising for healing the injured area. They offer great surface area and porosity, mimicking the fibrous extracellular matrix structure, facilitating cell adhesion, migration, and proliferation, and accelerating the wound healing process. Such properties resulted in countless applications of these materials in biomedical and tissue engineering, also as drug delivery systems for bioactive molecules to help tissue regeneration. The techniques used to engineer these fibers include spinning methods (electro-, rotary jet-), airbrushing, and 3D printing. These techniques have important advantages, such as easy-handle procedure and process parameters variability (type of polymer), but encounter some scalability problems. RJS is described as a simple and low-cost technique resulting in high efficiency and yield for fiber production, also capable of bioactive agents’ incorporation to improve the healing potential of RJS wound dressings. This review addresses the use of RJS to produce polymeric fibers, describing the concept, type of configuration, comparison to other spinning techniques, most commonly used polymers, and the relevant parameters that influence the manufacture of the fibers, for the ultimate use in the development of wound dressings. Full article

A new type of marine transportation engine, the pulsed detonation hydroramjet (PDH), which was first designed, manufactured, and tested by the present authors, has been further investigated in terms of the potential improvement of its propulsive performance. PDH is composed of a pulsed detonation tube (DT) inserted in the flow-through water guide. Thrust is developed by shock-induced pulsed water jets which are periodically emitted from the water guide nozzle. The measured values of the time-averaged thrust and specific impulse in the first operation cycle were shown to always be considerably higher than those in subsequent cycles, indicating the possibility of improving the overall thrust performance. The present manuscript is aimed at clarifying the reasons for, and eliminating, cycle-to-cycle variability during PDH operation, as well as optimization of the PDH design. An experimental model of the PDH with an optically transparent water guide was designed and manufactured. The cycle-to-cycle variability was found to be caused by the overexpansion of gaseous detonation products in the DT due to the inertia of water column in the water guide. Gas overexpansion caused the reverse flow of the gas–water mixture which filled the water guide and penetrated the DT, thus exerting a strong effect on PDH operation. To eliminate the cycle-to-cycle variability, a new PDH model was developed, manufactured, and tested. The model was equipped with a passive flap valve and active rotary valve and operated on the stochiometric propane–oxygen mixture. Its test firing showed that use of the valves made it possible to eliminate the cycle-to-cycle variability and nearly double the time-averaged thrust and specific impulse reaching 40 N and 550 s, respectively. Full article

The present study utilizes an acrylic (PMMA) plate with circular piezoelectric ceramics (PC) as an actuator to design and investigate five different types of piezo actuation jets (PAJs) with operating conditions. The results show that the heat transfer coefficient of a device of PAJ is 200% greater than that of a traditional rotary fan when PAJ is placed at the proper distance of 10 to 20 mm from the heat source, avoiding the suck back of surrounding fluids. The cooling effect of these five PAJs was calculated by employing the thermal analysis method and the convection thermal resistance of the optimal PAJ can be reduced by about 36%, while the voltage frequency, wind speed, and noise were all positively correlated. When the supplied piezoelectric frequency is 300 Hz, the decibel level of the noise is similar to that of a commercial rotary fan. The piezoelectric sheets had one of two diameters of 31 mm or 41 mm depending on the size of the tested PAJs. The power consumption of a single PAJ was less than 10% of that of a rotary fan. Among the five types of PAJ, the optimal one has the characteristics that the diameter of the piezoelectric sheet is 41 mm, the piezoelectric spacing is 2 mm, and the length of the opening is 4 mm. Furthermore, the optimal operating conditions are a voltage frequency of 300 Hz and a placement distance of 20 mm in the present study. Full article