Increasing Flow Rate Research Articles

Experimental evaluation of chemical sand stabilization and its optimization of composite sand control with squeeze gravel pack

Chemical stabilization is a viable solution for controlling the sand migration and production issues encountered in unconsolidated sandstone reservoirs. With numerous sand stabilizers available, screening the appropriate reagent and clarifying its utilization are crucial for enhancing sand control efficiency. This paper explores the impact of chemical sand stabilization on the expansion and diversification of sand production patterns and provides an experimental evaluation approach from an engineering standpoint. The evaluation experiments show that the sanding patterns may shift from collapse to a stabilized sanding cavity as the stabilizer content increases, and may remain relatively steady despite the increased flow rate under a high content of chemical sand stabilizer. Nevertheless, chemical stabilization has limited power to control unconsolidated sandstone, particularly in the early stages of fluid flushing when adequate support could not be provided, resulting in explosive sand production. Furthermore, their lifetime of efficacy in engineering applications is still insufficient. Based on the evaluation results, research on the construction method of mechanical-chemical sand control and parameter optimization including treatment range, dosage, and extrusion rate was established. The chemical stabilization screening method and mechanical-chemical design method presented in this work have been proven to be feasible through the successful application in the Gudong oilfield. The combination of chemical stabilization and squeeze gravel pack technology provides dual benefits of blocking coming sand near well and stabilizing weekly cemented sand far well, particularly for wells with extensive sanding history. It has a fair chance of helping with the engineering of sand management and production enhancement for unconsolidated sandstone reservoirs.

Purge–Mainstream Interactions in a Turbine Stage With Rotor Endwall Contouring

Abstract Purge flows are prevalent in modern gas turbine design, allowing for increased turbine entry temperatures. The purge flow passes through a rim seal and interacts with the mainstream flow, modifying the blade secondary flow structures and reducing stage efficiency. These structures may be controlled using end wall contouring (EWC), though experimental demonstration of their benefit is seldom reported in the literature. The optically accessible turbine at the University of Bath was designed to directly measure and visualize the flow field within the blade passage for a rotor with EWC. The single-stage turbine enables phase-locked flow field measurements with volumetric particle image velocimetry (PIV). Purge flow was supplied to investigate a range of operating conditions in which the secondary flow structures were modified. The modular turbine rotor allowed for expedient change of a bladed ring, or bling, featuring non-axisymmetric EWC. The identified secondary flow structures were the pressure-side leg of the horse shoe vortex (PS-HSV) and an egress vortex (EV) of concurrent rotational direction. An increase in purge flowrate monotonically shifted the EV toward the suction-side (SS) of the adjacent blade. The migration of the PS-HSV toward the SS caused the two aforementioned vortices to merge. The EWC rotor design included a leading-edge (LE) feature to alter the PS-HSV and a trough to guide the EV low spanwise in the passage and maintain displacement from the adjacent suction-side. The EWC rotor was found to be effective at altering the formation and positioning of the secondary flow structures at a range of purge flow conditions.

Analysis of Thermoacoustic Instabilities Using the Helmholtz Method in a Swirled Premixed Combustor

The Helmholtz method is developed to predict the self-excited thermoacoustic instabilities in a gas turbine combustor, combining flame describing functions, the measured damping rates under the firing condition, and the non-uniform spatial distributions of the physical parameters. The impact of the hydrodynamic and geometrical parameters on the thermoacoustic instabilities is investigated. The measured damping rates show lower values under a hot condition compared with those in a cold state. The experimental results indicate that the relative errors of the predicted eigenfrequencies and the velocity fluctuation levels are below 10%. The pressure amplitude decreases and the phase increases in the axial direction, indicating a typical 1/4-wavelengh mode. At a higher equivalence ratio, the mode shape in the axial direction becomes steeper due to the elevated fluctuation amplitude at the pressure antinode after enhancing the thermal power. When the air flow rate increases, the discrepancies between the pressure shape on the flame tube side and that on the plenum side are reduced. The velocity fluctuation level increases as the combustor length increases at a constant damping rate. In fact, the velocity fluctuation level first increases and then declines, caused by more significant damping rates when employing longer flame tubes. Self-excited thermoacoustic instabilities can be well predicted using the proposed method.

Numerical simulation of the effect of jet small orifice structure on cavitation characteristic and jet impact flow field

The jet impingement-negative pressure deamination reactor (JI-NPDR) is a continuous, non-clogging, and efficient deamination equipment characterized by its simple structure. Research has demonstrated that the fluid passing through the jet orifices in the jet impact section of the reactor leads to partial cavitation. This situation directly impacts the flow characteristics before jet impact and the gas-liquid separation behavior in the negative pressure separation section. Therefore, this work proposes to utilize the CFD numerical simulation method to analyze the fluid cavitation evolution rules under the aspect ratio l/d structure of different jet orifices and to investigate the influence of orifice structure on the jet impact flow field. The results indicate that an increase in the liquid flow rate and the small orifice aspect ratio l/d promotes the conversion of pressure energy to kinetic energy, leading to an increase in cavitation intensity in the jet orifice. Furthermore, the evolution behavior of the jet impact flow field can be effectively controlled based on the l/d structural parameter of the small orifice aspect ratio. The research results can provide fundamental data support for the structural optimization design and engineering application of the JI-NPDR.

Numerical investigation of mixing performance for a helical tangential porous tube-in-tube microchannel reactor

The tube-in-tube microchannel reactor (TMCR) is widely applied in chemical engineering and material industries. Two or more fluids are mixed in the annular channel of TMCR. This work aims to introduce a helical tangential porous tube-in-tube microchannel reactor (HTP-TMCR). The performance of HTP-TMCR is analyzed using computational fluid dynamics (CFD) method, focusing on three aspects: mixing index, pressure drop, and velocity distribution. Additionally, this study investigates the impacts of four geometric parameters, including left and right helical directions, pitch, pore size, and length of the non-porous zone, on the mixing performance of HTP-TMCR. The simulation results reveal that the mixing index initially decreases as the flow rate increases, reaching its lowest point (approximately 75%) at Q=2 L/h. Subsequently, there is a sharp rise to a second inflection point at Q=10 L/h, followed by a gradual progression stabilizing around 95%. Specifically, the left helical configuration demonstrates superior performance compared to the right one. Optimal mixing is achieved at low flow rates when the pitch is 4 mm and the pore size is 0.4 mm. Designing the length of the non-porous zone to be 5 mm is recommended. Furthermore, the characteristic of pressure drop for HTP-TMCR indicates its potential for commercial applications.

A Comparative Study of the Mode-Decomposed Characteristics of the Asymmetricity of a Vortex Rope with Flow Rate Variation

In hydro turbines, the draft tube vortex rope is one of the most crucial impact factors causing pressure pulsation and vibration. It is affected by operating conditions due to differences in the flow rate and state and can be symmetric or asymmetric along the rotational direction. It may influence the stability of draft tube flow. To achieve a better understanding, in this work, dynamic mode decomposition is used in a draft tube case study of a simplification of a vortex rope. As the flow rate increases, the shape of the vortex rope becomes clear, and the flow rotation becomes more significant as the inlet flow rate increases. Dynamic mode decomposition was used to determine the relative frequencies, which were 0 (averaged), 0.7 times, and 1.4 times the features of the reference frequency. As the inlet flow rate increases, the order of high-energy modes and their influence on the vortex rope gradually increase, and this characteristic is exhibited further downstream of the draft tube. When the inlet flow rate is low, the impact of mode noise is greater. As the flow velocity increases, the noise weakens and the rotation mode becomes more apparent. Identifying the mode of the vortex flow helps extract characteristics of the vortex rope flow under different operating conditions, providing a richer data-driven basis for an in-depth analysis of the impact of operating conditions on the flow stability of a draft tube.

Unstable Coalescence Mechanism and Influencing Factors of Heterogeneous Oil Droplets.

The use of a surfactant solution during oil and gas field development might improve the recovery rate of oil reservoirs. However, the serious emulsification of the produced liquid will bring challenges to the subsequent treatment process and storage and transportation. It is urgent to understand the coalescence mechanism of crude oil under the action of surfactant solution. This research investigates the coalescence mechanism of numerous oil droplets under liquid flow perturbation. The model was established to study the coalescence process of multiple oil droplets. The effects of the number of oil droplets under homogeneous conditions, the size of oil droplets, and the distance between oil droplets under non-homogeneous conditions on the coalescence process were analyzed. Meanwhile, the change rules of the completion time of oil droplet coalescence were drawn. The results show that the smaller the size of individual oil droplets under non-homogeneous conditions, the longer the coalescence completion time is, and when the size of individual oil droplets reaches the nanometer scale, the time for coalescence of oil droplets is dramatically prolonged. Compared to static circumstances, the time it takes for oil droplets to coalesce is somewhat shorter under gravity. In the fluid flow process, in the laminar flow zone, the coalescence time of oil droplets decreases with the increase of the liquid flow rate. However, in the turbulent flow zone, the coalescence time of oil droplets increases with the increase in the liquid flow rate. The coalescence time is in the range of 600~1000 ms in the flow rate of 0.05~0.2 m/s. In the presence of surfactants, the oil content in the emulsion system increases under the influence of pumping flow. The change in oil content rate with various surfactants is less impacted by flow rate, owing to the stable emulsion structure created by the extracted fluid within the reservoir. The study findings presented in this research provide technical assistance for effective crude oil storage and transportation.

Hydrogen-assisted chemical vapor deposition for heteroepitaxial growth of pure ε-Ga2O3 films

This study presents a novel approach to control the crystalline phase and surface morphology of substable ε-Ga2O3 thin films by regulating the hydrogen flow rate during chemical vapor deposition (CVD). The objective is to achieve high-quality and cost-effective heteroepitaxial pure-phase single-crystalline ε-Ga2O3 thin films on sapphire substrates. The crystalline phases and crystalline qualities of the thin films were determined by X-ray diffraction (XRD) and Raman spectroscopy. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) results show that the surface of the ε-Ga2O3 films prepared by this method is flat and the minimum value of the surface roughness (RMS) is 4.130 nm. We explain the reason for the differences in the surface morphology of the films from the point of view of hydrogen passivation. Measurements by UV–Visible spectrophotometer, the UV cut-off edge is located at 250 nm and the optical band gap is about 4.9 eV. The experimental results show that with the increase of hydrogen flow rate, the content of β-Ga2O3 in the films and the surface roughness and maximum height of the contour (RZ) decreases, until a smooth surface of the pure-phase ε-Ga2O3 film is produced. The success of the chemical vapor deposition method for heterogeneous epitaxy of high-quality ε-Ga2O3 films on sapphire substrates greatly reduces the production cost and expensive investment in production equipment, which makes its application in high electron mobility transistors, piezoelectric resonators, and sun-blind detectors have great potential, and at the same time, this method provides ideas for the preparation of other metastable materials.

Assessing the efficacy of magnetic water treatment: A concise review and experimental investigation

The utilization of magnetic water treatment has gained significant attention as a promising method for addressing scaling and water quality issues. This strategy has attracted interest due to its ability to potentially alter the behavior of dissolved particles in water. This investigation aimed to examine the impact of magnetic water treatment utilizing two different pipe materials, "iron pipe" and "PVC pipe", with a specific emphasis on the levels of total dissolved salts (TDS). Unexpectedly, the research findings indicate a positive correlation between the number of coil turns and the levels of TDS, which contradicts the popular belief that magnetic treatment would lead to a decrease in TDS. For instance, at a flow rate of 1 mL/s, TDS levels increase from an average of 265 ppm to roughly 277 ppm utilizing 500 and 2000 coil turns around an iron pipe, respectively. Similarly, when using a PVC pipe, TDS levels increase from around 263 ppm to 271 ppm as the magnetic field intensity increases. Furthermore, experiments carried out at an increased flow rate under a constant magnetic field strength show an inverse relationship with TDS. The TDS levels fall from 265 ppm to 261 ppm and from 263 ppm to 260 ppm as the flow rate rises from 1 mL/s to 6 mL/s for iron and PVC pipes, respectively. This intriguing phenomenon presents a challenge to long-held theories and highlights the complex relationship between magnetic fields, pipe materials, and water chemistry. Despite the unexpected results, the increase in the total dissolved salts indicates a possible improvement in reducing scaling, a common problem in fluid systems. In this discourse, this study analyzes the ramifications of these discoveries and underscores the necessity for additional investigation in order to elucidate the intricate mechanisms that underlie these interactions and enhance the efficacy of magnetic water treatment approaches. This research enhances the comprehension of water treatment strategies and emphasizes the significance of customizing procedures to suit individual scenarios in order to achieve efficient water quality control.

Memory and scission effects of polymers on the flow regime of polyethylene oxide solutions in continuous abrupt contraction–expansion microchannels with different cavity lengths

This study experimentally observes the flow regimes of polyethylene oxide solutions in continuous, abrupt contraction–expansion microchannels. In dilute solutions (0.5 × 10−3–1.5 × 10−3 wt. %), the effects of flow rate, concentration, and cavity length on flow characteristics in the contraction and expansion parts of each cavity are analyzed, including quantified calculations of normalized vortex lengths and extension rates. The results indicate that polymer memory and scission affect the flow transitions. Memory effects enhance vortex growth and scission weakens flow, and these effects occur continuously within the channel. Increased flow rates and cavity lengths intensify polymer scission, accelerating the transitions from elastic instability to corner vortex, lip vortex, and then to steady vortex-free flows in the contraction parts and from steady vortex-free flows to lip and corner vortices in the expansion parts. The flow-regime transitions for concentrations from 0.01 to 0.4 wt. % for dilute and unentangled semi-dilute solutions at various flow rates are summarized in the Reynolds and Weissenberg number spaces. Polymer chains tend to become entangled in higher-concentration solutions, rendering the solution rigid and inducing complex flow regimes.

Experimental study on hemodynamics of an end-to-side anastomosis

A three-dimensional and three-component velocity measurement on the flow field in a 45° end-to-side anastomosis model is conducted to investigate the hemodynamics, which is an important factor to the intimal hyperplasia formation and graft failure after surgery. Thanks to the advanced volumetric measurement technology of tomographic particle image velocimetry, the recirculation zone, low-speed region, and the spiral flow structures can be visualized. As a result, the flow field of three cases with the local maximum velocity of 0.15, 0.8, and 1.4 m/s are visible and the inlet velocity profile tends to be skewed as the flow rate increases. The mean vorticity contours indicate that the positive vortex center rotates 6.47°, 50.23°, and 90.4° and the negative vortex center rotates 20.44°, 15.73°, and 68.47°, respectively, in three cases. The instantaneous vortex structures identified by the λci criterion demonstrate two large-scale vortex structures in the distal section. The two vortices have the tendency to intertwine while one of them decays earlier. The wall shear stress (WSS) distributions on the entire model with the local maximum of 0.8, 5.8, and 13.8 Pa in three cases have been quantitatively achieved. The abnormal WSS and WSS gradient can help localize risk areas and understand the intimal hyperplasia formation. A detailed illustration of hemodynamics inside the 45° end-to-side anastomosis model has been provided, which demonstrates more comprehensive large-scale flow structures and abnormal WSS regions. Combined with the information of flow structures and WSS distribution, the understanding of the hemodynamics in the anastomosis can be strengthened.

Numerical study on the uniform distribution of flow field of airflow dryer

The uniformity of hot air flow inside the airflow dryer not only affects the moisture distribution at the outlet, but also affects the quality of the product. Based on the guide plate structure of the SH23A airflow tobacco dryer, a gradient curved guide plate dryer is designed, and the flow field distribution of the dryer is numerically investigated under different flow distribution conditions at the hot air inlet and flue gas inlet. The results show that the airflow uniformity is affected by the flow distribution at the inlet of the heated air and the inlet of the cigarette smoke, the structure of the guide plate, etc., the non-uniformity coefficient decreases with the increase of hot air inlet flow rate. The non-uniformity coefficient of tapered arc deflector decreases by 9–12 %.

Enhancing heat transfer performance of aluminum-based vapor chamber with a novel bionic wick structure fabricated using additive manufacturing

Given the lightweight nature and excellent thermal conductivity of aluminum, it offers significant potential for light-weighting of phase-change cooling components. To further enhance the thermal performance of aluminum-based vapor chambers, this study utilized selective laser melting (SLM) to design and integrally manufacture the slightly oleophilic wick for the condenser of the aluminum-based vapor chamber, along with three different superoleophilic wick structures for the evaporator: the gyroid bionic composite porous wick vapor chamber (GBCPVC), the groove composite porous wick vapor chamber (GCPVC), and the uniform porous wick vapor chamber (UPVC). A water-cooling experimental setup was established, and the effects of wick structure, cooling water flow rate, and cooling water temperature on the maximum heat load, temperature uniformity, and thermal resistance of vapor chambers were systematically investigated. The results indicated that the gyroid bionic porous wick structure significantly enhanced the thermal performance of the vapor chamber. Under the same conditions, GBCPVC exhibited lower thermal resistance and superior temperature uniformity, achieving a higher heat load than GCPVC and UPVC. When the cooling water temperature was decreased, its maximum heat load significantly increased. Specifically, at 15 °C, the maximum heat load for GBCPVC reached 300 W, an increase of 33.33 % and 53.33 % compared to 25 °C and 35 °C, respectively. Conversely, a rise in cooling water temperature enhanced the temperature uniformity and reduced thermal resistance of CBCPVC. At 35 °C and a heat load of 120 W, GBCPVC achieved a minimum thermal resistance of 0.034 K/W and a maximum temperature difference of 1.46 °C. Additionally, an increased flow rate enhanced the maximum heat load of GBCPVC, and under high heat loads, it could also reduce the thermal resistance and improve temperature uniformity. This study provides new insights and solutions for the thermal management of phase-change cooling components in aerospace electronic devices.

Study on spray characteristics of a compact pressure swirl nozzle integrating tangential inlet flow channel and swirl chamber

Pressure swirl nozzles are widely applied in various heat and mass transfer applications due to advantages of reliable performance, simple structure, and easy processing. However, the complex design of the nozzle structure makes it difficult to miniaturize the pressure swirl nozzle, which restricts its use in limited spaces. In this study, a compact pressure swirl nozzle is proposed by merging a swirl chamber with the tangential inlet flow channel, addressing the issue of liquid atomization in limited spaces. The key geometric parameters are determined based on the internal flow properties by swirl chamber simulation. A spray test bench utilizing a phase Doppler particle analyzer and a high-speed camera was built to study the effect of pressure drop, geometric size, and nozzle inlet shape on spray characteristics. The simulation results show that the nozzle diameter and inlet shape are the main factors affecting flow in the swirl chamber. The experimental results further demonstrate that increasing nozzle diameter increases flow rate and spray cone angle, causing the droplets to move to the spray edge. The spray characteristics are affected by the inlet shape of the nozzle hole: radial velocity and particle size show a wider range of change with a funnel-shaped inlet. Axial velocity and pressure drop are obviously affected by a cylindrical-shaped inlet. This study provided a new design approach for pressure swirl nozzles and achieved flow rate of 5–35 l/h and Sauter mean diameter below 40 μm with an overall weight of 12 g. This compact nozzle construction is a reference for the design of atomizing nozzles in limited spaces.

Numerical and experimental analysis of the cavitation and flow characteristics in liquid nitrogen submersible pump

In this paper, the cavitation and flow characteristics of the unsteady liquid nitrogen (LN2) cavitating flow in a submersible pump are investigated through both experimental and numerical approaches. The performance curve of the LN2 submersible pump is obtained via experimental measurement. Numerical simulations are performed using a modified shear stress transport k–ω turbulence model, incorporating corrections for rotation and thermal effects as per the Schnerr–Sauer cavitation model. The numerical framework is verified by comparing the cavitation morphology features with previously reported visual data of the LN2 inducer and aligning pump performance data with those obtained from experimental tests of the LN2 submersible pump. The results indicate that cavitation at the designed flow rate predominantly manifests as tip clearance vortex cavitation in the inducer. Increased flow rates exacerbate cavitation, potentially obstructing the flow passage of the impeller. The vortex identification method and the vorticity transport equation are employed to identify the vortex structures and analyze the interaction between cavitation and vortices in the unsteady LN2 cavitating flow. The vortex structures primarily concentrate at the outlet of the impeller flow passage, largely attributed to the vortex dilation term and baroclinic torque. The influence of thermal effects on the cavitation flow of submersible pumps is analyzed. An entropy production analysis model, comprehensively involving various contributing factors, is proposed and utilized to accurately predict the entropy production rate within the pump. This study not only offers an effective numerical approach but also provides valuable insight into the cavitation flow characteristics of the LN2 submersible pump.

Effect of perforation density distribution on production of perforated horizontal wellbore

To address the issue of horizontal well production affected by the distribution of perforation density in the wellbore, a numerical model for simulating two-phase flow in a horizontal well is established under two perforation density distribution conditions (i.e. increasing the perforation density at inlet and outlet sections respectively). The simulation results are compared with experimental results to verify the reliability of the numerical simulation method. The behaviors of the total pressure drop, superficial velocity of air-water two-phase flow, void fraction, liquid film thickness, air production and liquid production that occur with various flow patterns are investigated under two perforation density distribution conditions based on the numerical model. The total pressure drop, superficial velocity of the mixture and void fraction increase with the air flow rate when the water flow rate is constant. The liquid film thickness decreases when the air flow rate increases. The liquid and air productions increase when the perforation density increases at the inlet section compared with increasing the perforation density at the outlet section of the perforated horizontal wellbore. It is noted that the air production increases with the air flow rate. Liquid production increases with the bubble flow and begins to decrease at the transition point of the slug–stratified flow, then increases through the stratified wave flow. The normalized liquid flux is higher when the perforation density increases at the inlet section, and increases with the radial air flow rate.

Study on Flow Characteristics of Venturi Accelerated Vortex Drainage Tool in Horizontal Gas Well

Vortex drainage gas recovery has been used to carry liquid from gas wells. However, the traditional vortex tools in gas wells cannot produce long effective distance spiral flow at a low gas flow rate, and their operating mechanism has not been thoroughly analyzed. In this paper, the venturi acceleration vortex tool for a horizontal gas well is designed to improve drainage performance. The tube drainage, the vortex tool, and the venturi accelerated vortex tool were applied in a horizontal tube to investigate their drainage capacities by a horizontal well multiphase flow experimental device. The influence of different gas flow rates and liquid flow rates on the length of the spiral flow and pressure drop produced by the three tools was analyzed. The results show that the vortex tool can convert the gas–liquid mixing flow into the gas–liquid separation flow, that is, the liquid flows spirally along the wall and the gas flows in the center of the horizontal tube. Compared with the vortex tool, the venturi accelerated vortex tool can form a longer and more stable spiral flow. The laminar spiral flow reduces the total pressure drop in the tube. The length of the spiral flow increases with the increase in the gas flow rate. With the increase in the liquid flow rate, the spiral flow is not clear because of the turbulent flow. The length of the spiral flow and the pressure drop for the venturi accelerated vortex tool with different gas and liquid flow rates are analyzed to guide the application of the tool. This study provides a new means for the drainage of a horizontal gas well and further clarifies the working mechanism of the vortex drainage tool.

Научно-технологические основы разработки месторождений подземных вод с принудительным самоизливом

Introduction. A two-well borehole system is proposed, providing for the extraction of groundwater by forced self-discharge. The essence is to create conditions for the emergence of a down hole energy source in the form of hydraulic shocks, alternating hydraulic impulses affecting aquifers and ensuring the rise of water to a height. Materials and methods of research. A block diagram of a two-well circulation system of wells consisting of an above-ground tank, an injection well with a ledge, a water-lifting well connected by an intermediate trunk. The objects of the study are the shape of the above–ground tank, its connection with the injection well, the location of the ledge and the conditions for conducting a water circulation channel from the ledge to the above-ground tank. Methods – calculation of the energy characteristics of a two-well system, experiments to study the mechanism of the origin of incomplete hydraulic shock, boundary values of the modes of water movement in the system and the coefficient of injection of rocks. They were carried out on the installation with the possibility of visual observation of the processes taking place in the system. Results. When an incomplete hydraulic shock occurs on the ledge of the injection well, the flow is divided into core and lateral components. The water flow from the tank into the well was in the range of 20–60 l/min. The origin of incomplete hydraulic shock occurred at a water flow rate of 20 l/min, with an increase in pressure up to 7.0 atmospheres. The boundary values of the laminar flow mode of water flow are 60 l/min. The height of the water rise (H) mainly depends on the depth of origin of incomplete hydraulic shock (H1). The ejection coefficient of rocks decreases with increasing flow rate of the working flow. Discussion. The results of the study are due to the design features of the elements of the two-well circulation system of wells. The operating conditions of the system are the type of communication ground tank – injection well – aquifer, the location of the ledge, the execution of the water circulation channel from the ledge to the entrance to the ground tank with one diameter, the preservation of the laminar flow regime of water, the exclusion of pressure loss and water leakage in the intermediate trunk. Conclusions. The conditions for the origin of a down hole energy source in the form of renewable hydraulic shocks, which have a hydro impulsive effect on aquifers, have been established. A block diagram of the injection and circulation system of wells for the extraction of groundwater by forced self-discharge has been formed. Resume. The validity of the idea of injection-forced self-discharge of groundwater is proved by the results of research. The results are applicable in the development of groundwater with low-pressure and non-pressure aquifers. The objects of future research are the optimal ratios of the diameter of the injection well and the passage section of the ledge, the expansion of the boundary values of the flow transition from laminar to turbulent motion, and an increase in the ejection coefficient.

Experimental study on the negative pressure loss generated by the gas influx process around a long borehole

In the process of gas extraction in long boreholes, gas influx in the radial direction causes a non-uniform variable mass flow field due to bore wall friction. This flow field can lead to a negative pressure decay along the hole length, thus affecting the gas extraction effect. With this effect in mind, a gas variation mass test was designed for pore-containing specimens with different pore wall roughnesses. It is also based on the variable mass flow pressure drop theory and analyzes the pressure variation, hole wall roughness, and gas influx rate inside the borehole. The result indicates that radial influx of gas along the borehole wall can interfere with the main flow in the borehole. The increase of the radial influx flow rate of the gas produces an obvious swirling phenomenon, which gradually makes the fluid mixing flow situation more and more complicated the more it differs from the mainstream velocity. The mainstream velocity and the pore wall influx velocity are the main factors causing mixing loss. The study results are important for understanding the long borehole gas sink process and the design of reasonable borehole parameters.

Троспия хлорид у детей: динамика симптома остаточной мочи при коррекции расстройств мочеиспускания

Background. A significant place among pediatric urination disorders is occupied by overactive bladder (OAB). Treatment involving the use of M-anticholinergics is aimed to suppress detrusor overactivity. The side effects of treatment include urination problems, incomplete bladder emptying (residual urine), and acute urinary retention. Methods. We monitored 20 children aged 5–15 years, among them 12 boys and 8 girls. The average age (М±δ) was 8.47 ± 3.46 years. The 2-day uroflow monitoring revealed residual urine (RU) in 9 patients (1–15 times per monitoring period). The urination volume and rate, as well as RU, were assessed by uroflow monitoring conducted at home using the SIGMA F uroflowmeter (RZN registration certificate No. 2020/11522 of 5.08.2020). One of the components of combination therapy was trospium chloride (Spasmex) in a dose of 10–15 mg per day, depending on the age and disorder. Statistical data processing was performed using the STATISTICA 10 (StatSoft, Inc., USA) and Excel (Microsoft Office 2016) software packages. The differences were considered significant at p<0.05. The descriptive statistics were presented as М±δ (where М was median, δ was standard deviation). Results. The average effective volume (AEV) of urination in the group was reduced by 10–86.5% relative to the age norm. Furthermore, incomplete bladder emptying was reported in 9 patients. After treatment, the minimum urine output volume and the maximum urine flow rate increased significantly, while the urination rate decreased. There were no significant changes in the urine output volume (average and maximum), however, an upward trend of the urine output volume was observed. No increase in the number of RU cases following prescription of trospium chloride was reported. In fact, the decrease in their number was recorded. Conclusion. Pediatric micturition cycle abnormalities also include the RU symptom. The M-anticholinergic drug, trospium chloride (Spasmex), in a daily dose of 10-15 mg represents a safe and effective medication option. Therapy lasting up to 2 months results in the significant increase in minimum bladder volume and maximum urine flow rate, the decrease in pollakiuria severity, but never changes the rate and amount of residual urine.