High-pressure Jet Research Articles

The Effect of High-Pressure Jet Cooling on Surface Roughness, Cutting Force and Chip Formation of Ti-6Al-4V ELI in High-Speed Turning

In the machining of difficult-to-machine metals, such as titanium-based alloys, the delivery of coolant with high pressure can increase machining efficiency and improve process stability through more efficient chip breaking and better cooling. Proper selection of machining conditions can also increase the productivity of the process by reducing cutting forces and tool wear rate. To investigate the effect of high-pressure jet cooling (HPJC) on cutting force, surface roughness, and chip formation of Ti-6Al-4V ELI in high-speed turning, Grade 5 Ti ELI turning tests were carried out under coolant pressure of 200 bar. A lower pressure of 6 bar was also used in this study to compare the results of the pressure change. In general, surface roughness increased as the feed rate increased at constant cutting speeds in experiments with both 6 bar and 200 bar coolant pressures. Even though 200 bar pressure provided a better cooling thus reduced cutting force, and tool wear rate; the surface roughness values ​​obtained from the experiments with 200 bar were relatively worse than the experiments with 6 bar pressure. It was also seen that 200 bar coolant pressure may result in instabilities in the turning process in terms of chip geometries and formations.

Numerical Exploration of Transverse Sonic Jet In Hypersonic Cross-flow

At high altitudes, due to low air density, the control response of highly agile and manoeuvrable aerospace vehicles through conventional aerodynamic surfaces is rather slow and inadequate. The control demand of such vehicles can be met very effectively with high-pressure side jets positioned at different locations of the vehicle. Additionally, as none of the components of passive jet control intrudes in the flow path in a passive state, no additional drag is incurred. CFD methods are increasingly being used to characterize jet-controlled aerospace vehicles. Before using in the design exercise, CFD methods need to be validated against reliable experimental results to find its range of applications and error band. In this work, a recent experimental study of transverse sonic injection into Mach 5 hypersonic stream is numerically explored by solving three-dimensional Reynolds Averaged Navier Stokes (RANS) equations using a commercial CFD solver. The computed surface pressures show a reasonable match with experimental results for different momentum ratios of jet and free stream flows. The predictive capabilities of different turbulence models were assessed. The spreading and penetration characteristics of the injectant are analysed from the computed data. The computed penetration and spreading of the injectant depicts nearly linear dependence with the momentum ratio.

Comparative evaluation and sensitivity analysis of multi-modelling and optimization of milling Ti–6Al–4V alloy with high-pressure coolant jets

An effective cooling method with the proper selection of process parameters can intensify the machining performance by reducing the loss of resources with better quality products. In this regard, modelling is an appropriate way of predicting responses in changing environment and optimization is an efficient tool of selecting the best process parameters based on the specific desire. With a view to enhance the machinability of Ti–6Al–4V alloy, the first attempt of the current study was to predict the performance characteristics of milling such as cutting force (N), specific cutting energy (J/mm3) and surface roughness (μm) with the variation of speed (m/min), feed (mm/min), depth of cut (mm) and cooling approach by developing mathematical models. For the present work, three different predictive models such as response surface methodology (RSM), artificial neural network (ANN), and adaptive neuro fuzzy inference system (ANFIS) was followed. Additionally, a comparative assessment of the used predictive models was carried out and ANFIS was noticed as the most accurate predictive model. After that, optimization of the selected responses was conducted by multiple-objective optimization on the basis of ratio analysis (MOORA) method where the relative weights of each response were defined by principal component analysis (PCA). For milling Ti–6Al–4V alloy within the specific boundary conditions, PCA-MOORA suggested an optimal parameter setting at 32 m/min speed, 22 mm/min feed rate, and 0.75 mm depth of cut with rotary high-pressure cooling. Finally, the sensitivity of the used MOORA method with the variation of unitary ratio was checked out to take a robust decision.

Testing of a novel multi-branch horizontal well remediation technology for in situ remediation of contaminated soil and groundwater

Soil and groundwater contamination has become a key issue in urban redevelopment. It is particularly difficult to use heavy equipment for the remediation of restricted sites or areas contaminated by factories that are still in operation. In this case, horizontal wells are considered a potentially useful technology as they can potentially remediate contamination areas located below buildings and other surface/subsurface obstacles. This research first introduces the principles and advantages and disadvantages of direct push injection, improved slant well, high-pressure rotary jet technology, horizontal reactive media treatment wells, and horizontal directional drilling well. The key aspects for promising in-situ remediation techniques were summarized as remediation well design, remediation agent injection technology and drill pipe and well wall sealing technology. Based on the requirements for key technologies, a novel multi-branch horizontal well in-situ remediation process was proposed, which integrates vertical/horizontal directional drilling, rotary injection, and expansion sealing techniques, and relevant supporting drilling and injecting equipment were developed. A bench test and field test were conducted to test drilling tool performance, drilling accuracy, and injection radius of influence. The results showed that the developed supporting drilling tool met the process requirements and could complete multi-branch horizontal well remediation engineering construction. The deviation between the measured depth and the design depth of the multi-branch horizontal well constructed using this technology was less than 9%, and the deviation between the depth displayed by the guidance instrument and the measured depth was less than 1%. The injection radius of influence in the test field measured from the monitoring wells was greater than or equal to 5 m. The results of this research can provide an effective method for the remediation of contaminated sites.

Performance evaluation of high-pressure cooling by using external rotary liquid applicator in milling Ti–6Al–4V alloy

An effective cooling mode with appropriate process parameters can enhance the machinability as well as productivity. In this regard, this study focuses on evaluating the machinability of widely used Ti–6Al–4V alloy with the use of high-pressure coolant jets compared to dry milling. A novel rotary applicator was designed and developed to feed high-pressure coolant jets without any drastic change of solid end mill cutter. Four flutes solid HSS end mill cutter was selected for machining because of its some intensive properties. Biodegradable VG-68 cutting oil was chosen as cutting fluid due to its better thermo-physical properties with higher flash points. Machinability was assessed at 16–32 m/min cutting speeds and feed rates of 0.08–0.16 mm/tooth with a constant depth of cut of 1.0 mm, taking into account the average cutting temperature, resultant cutting force, mean surface roughness, and tool wear. Dry milling produced the worst results for all of the investigated responses, with excessive tool wear due to the lack of cooling and lubrication. Compared to dry milling, high-pressure cooling (HPC) lowered average cutting temperature, resultant cutting force, and mean surface roughness by 11.21–21.57%, 8.63–13.12%, and 6.09–29.6%, respectively, whereas rotary high-pressure cooling (RHPC) reduced these parameters by 15.39–27.27%, 14.05–21.18%, 16.48–41.04%. RHPC's efficient cooling and lubrication increased the machinability of the Ti–6Al–4V alloy. Dry milling showed severe flank wear with increased built-up edge (BUE) development, abrasion, and adhesion, whereas HPC and RHPC dramatically reduced the severity of tool wear. In HPC and RHPC, the tool life was consequently increased by 6.8 and 9 min, respectively.

Analytical study on critical load and deformation of chip in high-pressure jet assisted machining

Analytical study on critical load and deformation of chip in high-pressure jet assisted machining

Numerical study on the effect of complex structural barrier walls on high-pressure hydrogen horizontal jet flames

Hydrogen has the potential to produce energy with no emissions, and therefore offers a strategic opportunity for rapid development of renewable energy storage. However, jet flames caused by the leakage of high-pressure hydrogen may cause casualties and damage equipment, so the safety issues associated with hydrogen incidents are a key issue restricting its development. Barrier walls can be an important mitigative action to reduce the hazard of hydrogen jet flames. Previous studies have evaluated the protective effect of different vertical or inclined arrangements of a single barrier wall in the vertical direction. However, in the vertical direction, a single barrier wall is not sufficient to reduce the hazards associated with high-pressure hydrogen jet flames. In this paper, a two-dimensional CFD model of high-pressure hydrogen jet flames are established. A simplified form of the hydrogen real gas equation of state is used to describe the complex behavior of high-pressure hydrogen. This CFD study employs the standard k-ε turbulence model, the eddy dissipation concept (EDC) model, and the discrete ordinate (DO) radiation model. The results display good agreement with the experimentally obtained flame shape and thermal radiation values, which confirms the applicability of the model. Based on this model, the characteristics of high-pressure jet flames are systematically studied under different forms of barrier walls and different pressures of hydrogen storage. Compared with the vertical barrier wall, barrier walls with complex structures can block the flames in front of the wall more effectively. This is proven through a remarkable decline in the vertical flame length and a reduction in the high temperature area. Comparing the five barrier wall patterns for their combined flame shape and flame temperature, it is more preferred to choose 60° Plate. The results of this study will help to better analyze the consequences of hydrogen jet flames and provide guidance for better design of barrier walls for mitigation.

Particle movement and hydraulic impact in dense two-phase solid–liquid flow inside a water–iron sand jet

High-pressure and multi-phase jet technology is widely used in applications to reduce energy consumption, especially when cleaning steel strips. The dynamics of jet flow and energy transfer in two-phase solid–liquid flow is intricate, particularly in the presence of dense particles. Constructing mathematical models of such interactions is challenging due to the complexity of particle-to-particle and particle-to-fluid contact. An optimized method based on a dense discrete-phase model is proposed to accurately track the movement of dense particles in this study. We used the proposed approach to investigate the movement of particles, the corresponding mechanism of the flow field, and the characteristics of wear while considering the hydraulic forces acting on the particles by using minimal resources for calculation. The results indicate that this method can be used to accurately count an extremely large number of particles and capture their dynamics. The particles acquired kinetic energy from the high-pressure jet, and most of them moved downstream with the main flow. However, part of them migrated toward the bilateral region, participated in the formation and evolution of the vortex, and washed the bottom of a mixture chamber. The impact of the particles at the bottom of a mixing chamber exhibited time-averaged characteristics in terms of the number of collisions and the average normal and tangential forces. The curve of the rate of average wear includes three stages: single-phase flow (no wear), mixed flow (rapid wear), and stable flow (rapid and stable wear at a rate of 9.29 × 10−4 mm/s).

Research and Application of High-Pressure Rotary Jet Method in the Seepage Treatment of Heavy Metal Tailing Ponds of Southwest China.

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.

Prediction and mechanism of surface evolution in high-pressure slurry jet micro-machining of channels

Recent advances in abrasive water jet (AWJ) processes have enabled controlled-depth micro milling for a variety of applications, such as micro fluidic chip manufacturing. However, AWJ micro milling can be difficult to control and its successful application requires judicious selection of the process parameters. Since the mechanics of the process have not been fully understood, prediction of the machined topography arising from a set of process parameters is difficult. The present work combines computational fluid dynamics, Lagrangian particle tracking, and a deformed geometry surface evolution technique into a comprehensive model that predicts the evolving shape of micro-channels milled on 6061-T6 aluminum plates using high-pressure abrasive slurry jet machining (HASJM). Requiring calibration using only a single channel centerline depth, the model could predict the machined profiles of micro-channels milled using multiple nozzle passes with less than a 2% error. The model was also used to investigate the underlying physics of the machining process. This allowed experimental observations to be explained in terms of the changes that occur, due to the evolving eroded shape, in stagnation zone size, particle ricochet behavior, secondary slurry flow, and local particle impact angles and velocities. Overall, the work shows that such models can not only very accurately predict evolving machined topography, but also be very useful tools to understand abrasive jet machining mechanisms which occur on time scales which are too brief to be directly observed experimentally.

Current Status of Hard Turning in Manufacturing: Aspects of Cooling Strategy and Sustainability

In recent years, hard turning has been found to be a well-known substitute for traditional grinding for acquiring the finish quality of hardened steel without sacrificing productivity. There are many issues that should be carefully understood and dealt with to attain efficacious performance in hard turning. This article discusses modern manufacturing challenges with a focus on analyzing the current state of the art of the hard turning process in terms of ensuring more environmentally friendly manufacturing through the use of greener cooling methods such as dry, wet/flood cooling, the minimum quantity of lubricant (MQL), high-pressure jet cooling, solid lubricant, nanofluids, ionic liquids (ILs), cryogenic cooling, and hybrid cooling. Nanofluids combined with the MQL system were found to be the superior cooling technique in comparison to dry, wet/flood, and MQL. Cryo-machining also provided superior performance by limiting the cutting temperature during hard turning. The performance of hybrid cooling (MQL + cryogenic) seems to have been superior to MQL and cryogenic coolant alone because it combined the benefits of lubrication and cooling from MQL and cryogenic systems, respectively. The addition of ILs to base fluids or nanofluids improves the thermal properties of the mixed fluid, resulting in better surface quality, lower tool wear, and longer tool life. Furthermore, the purpose of this study is to summarize the various LCA software used for analyzing the sustainability of the hard turning process. Overall, this paper can serve as a resource for researchers and manufacturers working in the field of sustainable machining.

Characteristics of In Situ Stress and Reservoir Pressure in Deep Coal Seams and Their Influences on Reservoir Depletion: A Field Case Study

The production of coalbed methane resources is greatly dependent on the reservoir depletion process. To improve the depressurization efficiency of deep coalbed methane (DCBM) reservoirs, the fluid production characteristics and implications of in situ stress and reservoir pressure for reservoir depletion in the eastern margin of the Ordos Basin are analyzed. The results indicate that the duration of the single-phase water production stage is overall long, with the gas declining stage occurring too early. The daily gas production volume of DCBM wells is only a few hundred m3. For DCBM reservoirs, it is considered that in situ stress, initial reservoir pressure, and critical desorption pressure significantly affect the fluid production and depressurization process. A high in situ stress in deep coal seams is likely to damage the flow conductivity of fracture systems due to the increase in effective stress during reservoir depletion. Based on the in situ stress characteristics of deep coal seams and their implications for reservoir depletion, we propose that the depressurization of DCBM reservoirs during gas production can be promoted via a new method of stress release. Slots or cavities created in coal seams by high-pressure hydraulic jet can provide space for stress release. This novel depressurization method could help improve the gas production efficiency of DCBM reservoirs.

Numerical study of hydrogen jet in methane / air premixed atmosphere

The work presented a numerical study on the transient characteristics of under-expanded hydrogen jets from a cylindrical nozzle. The finite-volume solution was adopted in the two-dimensional simulation of high-pressure chocked hydrogen jets, by solving the Navier-Stokes equations for gas phase flow. Numerical analyses were respectively performed over the micro level to characterize the fine structures, and over macro levels to explore the key global parameters of the gaseous jets. Parameterization work was conducted in terms of the microscopic characteristics of jets, such as, the length of jet core, the diameter of jet vortex, and the key global parameters, i.e. the penetration and the steady fuel injection rate. The effects of the injection parameters on the micro-structure and macro characteristics were hence quantified.

Experimental investigation on high-pressure methane jet characteristic single-hole injector

High-pressure gas direct injection (DI) technology benefits engines with high efficiency and clean emissions, and the gas jet process causes crucial effects especially inside an mm-size space. This study presents an investigation on the high-pressure methane jet characteristics from a single-hole injector by analysing jet performance parameters including jet impact force, gas jet impulse, and jet mass flow rate. The results show that the methane jet exhibited a two-zone behaviour along the jet direction in the spatial dimension induced by high-speed jet flow from the nozzle: zone 1 near the nozzle—the jet impact force and jet impulse increased consistently except for a fluctuation due to shock wave effects induced by the sonic jet and no entrainment occurs, and zone II farther away from the nozzle—the jet impact force and jet impulse became stable when the shock wave effects became weak and the jet impulse was conserved with a linear conservation boundary. The Mach disk height was exactly the turning point of two zones. Moreover, the methane jet parameters, such as the methane jet mass flow rate, jet initial jet impact force, jet impulse, and Reynolds number had a monotonous and linearly increasing correlation with injection pressure.

High frequency jet-ventilation anaesthesia in patients with laryngeal patholog

Airway management in laryngeal surgeries is a challenge for an anesthesiologist due to sharing of airway with a surgeon. The airway is often compromised with potential for perioperative worsening. Introduction of high-frequency jet ventilation (HFJV) in 1970 offered a new modality to secure airway in the laryngology procedures, excluding the disadvantages of classic tracheal intubation. HFJV is characterized by delivery of small tidal volumes (1–2 ml/kg) from a high-pressure jet at supraphysiological frequencies (1–10 Hz) followed by passive expiration. At ENT clinic of “T.Moșneaga” hospital HFJV are used for several years. Applied via supraglottic aproach, HFJV is first choice in patients with severe laryngeal obstruction, lesions of posterior glottic regions, a lot of pacients being suffering of laryngeal papillomatosis. This method can be safely used in microlaryngeal surgery, excluding a lot of serious intraoperative complications, esspecially combustions of conventional endotracheal tubes. Till now, there are not reported complications in our local practice of HFJV.

Full-Scale Loading Test of Jet Grouting in the Artificial Island–Immersed Tunnel Transition Area of the Hong Kong–Zhuhai–Macau Sea Link

In the Hong Kong–Zhuhai–Macau Bridge mega project, several ground treatment methods were applied in the transition area between the artificial island and immersed tube tunnels to reduce the potential uneven foundation settlement underlying the tunnel, as the backfilled sand layer is more than 10 m around it. One of the foundation improvement methods involves the combination of preload and high-pressure jet grouting (HPJG) columns. Current field tests, such as core bowling, standard penetration test, and plate loading test, are not suitable for evaluating the strength of this reinforced foundation. This study presents a full-scale load test to examine the construction quality and effects of an HPJG-reinforced foundation. A novel method was designed based on the Boussinesq equation to simulate the additional stress distribution from the immersed tube tunnel. The tangent modulus method considering the impact of modulus nonlinearity was employed to calculate the nonlinear settlement of the treated foundation. Preferable settlement results were obtained using a set of pre-embedded high-precision hydrostatic leveling systems. Both the measured data and calculated settlement demonstrate the reasonableness of the present in situ test.

Experimental investigation on the reinforcement of a high-pressure jet grouting pile for an ultra-shallow tunnel in a strongly weathered stratum

In this paper, the performance of a high-pressure grouting material and consolidation body, the key parameters of tunnel surrounding rock reinforcement, and the field reinforcement effect are compared and studied. The results show that 1) the compressive strength, elastic modulus, and seepage resistance of the consolidation body are related to the water–cement ratio. The permeability of the consolidation body increases with increasing water–cement ratio under the constant head; under the condition of a certain water–cement ratio, the strength increases with an increase in cement content. To meet the construction requirements and the slurry stability, a small water–cement ratio is appropriate. 2) Slurry pressure, rotary spray speed, and lifting speed on the single pile static load bearing capacity have a significant impact. Under the same static load conditions, the greater the slurry pressure, the lower the cumulative settlement value of the single pile, the cumulative settlement value increases less, and the amount of change in rebound is the same; with the increase in the rotational speed of the rotary spray, the lower the cumulative settlement value of the single pile, and the rate of change of the cumulative settlement value of the single pile decreases; and with the increase in the lifting speed, the cumulative settlement value of the single pile increases and the rate of change of the cumulative settlement value decreases. 3) The pile body cement soil is more uniform, has high strength, and is brittle, and the stratum where the slurry part is located is a loose powder clay layer and sandy layer. 4) After high-pressure jet grouting pile reinforcement, the top surrounding rock is more stable after the excavation of an ultra-shallow buried tunnel, the fissures between the surrounding rocks are filled with cement soil consolidation, and the integrity is improved. Certain piles also play a certain role in stopping water; high-pressure jet grouting pile reinforcement to improve the integrity of the surrounding rock played a role in consolidating the weak soil layer above the tunnel vault, creating conditions for the safe excavation of the shallow buried section of the tunnel.

Study of Flow Field Characteristics During the Impact of a High-pressure Gas Jet on a Bulk-loaded Liquid

A visual experiment platform for high-pressure gas jet impacting the bulk-loaded liquid was designed and built in order to investigate the real law of the interaction between the high-pressure gas jet and the liquid medium during the liquid-balance launch of rocket launcher. The experiments of single-phase gas jet injection and the high-pressure gas jet at different temperatures impacting the bulk-loaded liquid were carried out, and the effects of gas temperature on the characteristics of the gas-liquid flow field have been revealed. The results show that the turbulent mixing between the high-pressure gas jet and the liquid medium leads to the appearance of pressure fluctuations in the gas chamber connected to the nozzle. The higher the gas temperature, the greater the amplitude of the pressure fluctuations. Under the impact of high-pressure gas jet, a gas cavity with an arc-shaped head is formed inside the bulk-loaded liquid. The higher the gas temperature, the faster and more unstable the development of the gas cavity and the flow field. The displacement equation of the gas cavity confirms to the first-order exponential decay function, and the error between the fitting value of the established mathematical model and the measured value is within 2%.

Study on Dynamic Performance and Induced Breakdown of the Plasma-Triggered-Based Protective Gas Gap Switch

The plasma-triggered-based protective gas switch (PTGS) has obvious advantages in the control switch application of fast energy dissipation device used in the hybrid dc transmission projects. However, the high-pressure environment critically limits the plasma jet ability, easily leading to the trigger failure. Therefore, this article establishes a plasma-jet-triggered experimental platform to study the dynamic performance and induced breakdown laws of PTGS. It is shown that the evolution of plasma jet is divided into three stages: plasma jet of high-pressure, saturated stability, and dissipation. The induced breakdown mainly occurs in the high-pressure jet and saturated stability stage. The initial plasma jet velocity increases, as the energy storage capacitance and the charging voltage increase, making it faster to reach the jet length for induced breakdown, resulting in a significant reduction in switch-on time and improving the PTGS trigger stability. The increase in trigger gas pressure inhibits the plasma jet ability, but improves the electrical strength of PTGS. In order to achieve induce breakdown of PTGS, the plasma jet must reach the critical jet length. SF6 gas improves the insulation strength of PTGS and prevents the formation of plasma jet. To achieve stable trigger conduction, the trigger energy of PTGS must be increased. The findings can be used to develop theoretical guidance for improving the working performance of the high-voltage and large-capacity protective gas gap switches (GGSs).

Application of High-pressure Jet Grouting Pile in Deep Foundation Pit Excavation and Support Scheme around the Original Natural Foundation

Application of High-pressure Jet Grouting Pile in Deep Foundation Pit Excavation and Support Scheme around the Original Natural Foundation