Suction Pressure Research Articles

Commentary on "The Safety and Effectiveness of a Self-Made Negative Pressure Suction Device in the Treatment of Chronic Wounds".

Commentary on "The Safety and Effectiveness of a Self-Made Negative Pressure Suction Device in the Treatment of Chronic Wounds".

REFRIGERANT CHARGING UNIT FOR THE RESIDENTIAL AIR CONDITIONERS: AN EXPERIMENT

In the present work, an automatic R410A refrigerant charger for residential air conditioners is fabricated and tested. The charger operates on the throttling principle and uses the suction pressure of the compressor to estimate the refrigerant charge level. This helps to reduce the risk of compressor damage and ensures the correct composition ratio of R410A refrigerant when charged into the machine. The charging process is controlled by the LabVIEW platform, which provides adequate control and visualization of the charging process. The developed charger meets expectations in solving the technical problems encountered when charging R410A refrigerant for residential air conditioners. It is compact, portable and can be directly controlled through the LabVIEW interface, allowing real-time visualization of the charging process. The present work is expected to make a significant practical contribution, serving as a useful reference for the future manufacturing of compact portable equipment in the residential air conditioning field.

RADIATION AND THERMAL DIFFUSION EFFECTS ON VISCO-ELASTIC FLUID PAST A POROUS PLATE WITH CHEMICAL REACTION AND HEAT GENERATION

A free convective two dimensional MHD boundary layer flow of a non-Newtonian (visco-elastic) fluid past a vertical porous plate have been thoroughly researched in this paper. The thermal diffusion Effects are also analyzed in presence of chemical reaction and radiation. A steady suction pressure is maintained at the plate. A singular perturbation method has been used to solve the problem. The analytical results are obtained for different values of the various dimensionless parameters entering into the flow problem and discussed quantitatively.

Determining the Effects of Nasopharyngeal Suction with Negative and Positive Pressure: Randomised Controlled Trial

Objective: The study aims to determine the effects of nasopharyngeal suction with negative and positive pressure on pain level, respiratory parameters, and mucosal irritation in infants. Methods: This study was conducted as a posttest randomized controlled experimental research. The data was collected at Göztepe Training and Research Hospital between January and November 2020. While the positive pressure suction method was applied to the experimental group, the negative pressure suction method was applied to the control group. Results: It is determined that the pain level mean scores at the 1st and 5th minutes after the suction procedure are lower in the experimental group than in the control group (p

Standardized treatment of infection after anterior cruciate ligament reconstruction

Infection after anterior cruciate ligament reconstruction (ACLR) is a rare and catastrophic postoperative complication. The aims of this study were to investigate the diagnostic, treatment and rehabilitation measures for postoperative infection following after ACLR. A retrospective study was conducted on 1500 patients who underwent ACLR between January 2011 and January 2022. Twenty patients who met the criteria for summarizing the incidence patterns and treatment experiences were selected for a complete investigation of their diagnostic, therapeutic, and rehabilitation processes, as well as outpatient follow-up results. Among the 20 patients who developed postoperative infections, Staphylococcus aureus was the main pathogen (80%). The clinical manifestations mainly included fever (80%) and knee joint pain (100%). Laboratory tests demonstrated that C-reactive protein (CRP) levels were greater than 50 mmol/L in fifteen patients (75%). All of the patients received intravenous antibiotic therapy. Five patients (25%) of tendon socket infection were treated with continuous negative pressure suction irrigation, whereas the other fifteen patients with intra-articular infection were treated with arthroscopic debridement and continuous flushing. The Lysholm score of the affected knee was compared before treatment and 6 months after treatment, and the difference was statistically significant (t = 20.78, P < 0.001). The success rate of treatment was 100%, and there were no significant differences between patients who received secondary treatment and functional exercise and those who underwent ACLR in terms of knee joint function or range of motion during the same time period. Infection was rare after ACLR, however it was fatal, and the main pathogen was Staphylococcus aureus. Early diagnosis and a comprehensive treatment approach are pivotal for the successful management of postoperative infections following ACLR. The results of this study contribute valuable clinical insights for further refining surgical procedures, enhancing infection prevention measures, and optimizing rehabilitation protocols.

Experimental and numerical study on integrated film cooling of turbine endwall by upstream slot leakage and blade showerhead jets

Prior emphasis on isolated turbine cooling structures resulted in low coolant utilization, but research on coolant interactions of different components remains scarce. This paper experimentally and numerically investigates the interaction effects between two inherent coolant jets from the endwall slot and blade showerhead. Their combined effect on endwall aero-thermal performance is measured by an Infrared camera, and the secondary flows under coolant mix are analyzed. The results show that blade showerhead coolant can play secondary cooling effects on endwall through reattachment, and it can also influence the endwall cooling distribution through altering the secondary flow development near leading edge. At high slot mass flow ratio (MFR) of 2.3%, the showerhead jets lead to secondary endwall cooling effectiveness of up to 0.2 in pressure side junction and suction side hot ring when showerhead MFR is 0.36%. With a further increase in the showerhead coolant MFR to 0.77%, the showerhead jets push the horseshoe vortex to reattach on pressure side endwall, and thus a high cooling region is formed on pressure side endwall near the slot edge. At low slot MFR of 1.5%, the slot leakage mainly covers the suction side endwall with a large hot ring. The reattachment of showerhead coolant on endwall is weak when the showerhead MFR is 0.36%. When showerhead MFR increases to 0.77%, the showerhead coolant has an ideal secondary cooling effect on endwall suction side hot ring, pressure side upstream part endwall, and pressure side junction. The heat transfer coefficient within the pressure side hot ring and pressure side junction both reaches 400. This paper can guide the joint design of turbine blade and endwall cooling layouts.

Effect of Discharge Cooling using Condensate Water on the Performance of an Air Conditioner: A Field Testing

The effect of discharge cooling using condensate water from the evaporator on the performance of an air conditioner has been experimentally investigated. Instead of laboratory testing, the air conditioner was tested under real conditions, as is generally an AC unit installed in a room. The indoor unit was installed inside the room at a height of 2.6 m from the floor, while the outdoor unit was installed outside at floor level. In this research, the air conditioner was tested under two conditions, i.e., normal condition without discharge cooling and modified condition in which the condensate from the evaporator was flown and dripped to the discharge pipe. The use of discharge cooling could decrease suction and discharge pressure, as well as suction and discharge temperature. It also slightly decreases supply air temperature. Better performance of the air conditioner with the use of discharge cooling was shown by the decrease of power consumption by 3.5% and increase of cooling capacity by 2.45%. As a result, the coefficient of performance (COP) increases by 6.31%.

Emphasizing on the envelope spectra of hydraulic turbomachinery vibration response towards cavitation diagnosis

Cavitation attracts the interest of engineers who target the better understanding of its complex physics and the development of efficient detection tools. This research explores the effectiveness of vibration-based indicators in the prompt and effective diagnosis of cavitation initiating in the rotating flow fields of turbomachinery. The indicators are derived from the envelope spectra estimated with the use of Hilbert Transform, Spectral Kurtosis and Cyclic Spectral Correlation algorithms and data acquired from two semi-open impellers. By utilizing a transparent casing, the onset of cavitation can be observed, enabling the establishment of reliable criteria for evaluating the new indicators. Also, their applicability is assessed across a wide range of flow-rate and suction pressure conditions and in two different geometries. The results demonstrate the consistent ability of the indicators to exploit the high frequency carrier information related with the resonances excited from bubble implosions, to promptly and efficiently detect the phenomenon.

Investigation on the unsteady aerodynamic performance of the Drela AG 08 and Boeing B29 airfoils subjected to heaving motion

This article aims to investigate the unsteady flow characteristics of Drela AG08 and Boeing B29 airfoils when subjected to heaving motion. The influence of heave amplitude, heave frequency in terms of instantaneous force coefficients of the airfoil is investigated at Re = 5 × 104. Furthermore, the flow field investigations were carried out to analyze the Leading Edge Vortex (LEV) formation and its convection airfoil’s suction side. From the findings, a variation in the oscillation amplitude of force coefficients was observed and a non-sinusoidal behavior was also noticed. Additionally, a remarkable change in the instantaneous force coefficients (both qualitatively and quantitatively) is also observed with respect to the slight change in aforementioned parameters. A transition in the wake pattern from drag inducing to thrust producing is observed under certain conditions. It is observed that the flow separates at the leading edge by forming LEV on both airfoil’s suction side and pressure side. It is also noticed that whenever the flow departs the trailing edge, these vortices convect downstream of the airfoil and form alternating pattern of coherent vortices. With the increase in number of cycles, these vortices interfere with the previously shed vortices and affects the airfoil’s aerodynamic characteristics. From the investigations, it is observed that, by controlling the system parameters, the adverse effects of the LEV can be minimized.

Influence of Long Pressure and Short Suction Ventilation Parameters on Air Flow Field and Dust Migration in Driving Face

A combination of similar tests and numerical simulation was used to study the distribution of the air flow field and the dust field in the driving face under the conditions of long pressure and short suction ventilation. The results show that the air flow field is divided into return, jet, and vortex zones. When the distance (L) is 1.6 m, the wind speed (Va) is 8 m/s, and the ratio of pumped air volume to pressure air volume (Q) is 0.8, the total and exhaled dust concentration (Td, Rd, Tp, and Rp) at the driver’s and pedestrian’s position were the lowest. According to the grey correlation analysis, the importance of factors affecting Td and Tp is ranked as L &gt; Va &gt; Q, Rd is ranked as Va &gt; L &gt; Q, and Rp is as follows: Va &gt; Q &gt; L. The increase in Va and the decrease in L have a significant effect on the expulsion of exhaled dust.

Comparison of efficacy and safety of different suction pressure for speeding non-ventilated lung collapse in uniport video-assisted thoracoscopic surgery: a randomized-controlled trial

BackgroundThe bronchial suction has been applied in speeding lung collapse. Low suction pressure may not speed lung collapse, but high pressure causes occult lung injury. The aim of the study was to explore efficacy and safety of different suction pressure for speeding lung collapse.MethodsEighty-four subjects undergoing uniport video-assisted thoracoscopic surgery (VATS) were randomly assigned for non-suction (Group 0), -10 cmH2O suction pressure (Group − 10), and − 30 cmH2O suction pressure (Group − 30). The primary outcome were the lung collapse scores (LCS) at 0 min (T0) after the visualization of the lung using a 10-point visual analogue scale and area under the curve (AUC) of LCS over time. The secondary outcomes included disconnection from the ventilator, the assessment of occult lung injury using NOS-3 expression, histologic scores of lung injury, and lung W/D weight ratio, intraoperative hypoxemia, the incidence of perioperative pulmonary complications.ResultsBoth the LCS at T0 and AUC analysis showed that compared with Group 0, Group − 10 and Group − 30 significantly achieved good lung collapse (P < 0.05), but no difference between Group − 10 and Group − 30. Four patients in Group 0 were treated with disconnection maneuver. The assessment of occult lung injury showed no differences.ConclusionsApplying − 10 cmH2O suction pressure for 1 min when pleural incision is a relatively safe method to promote lung collapse without the occurrence of occult lung injury.Trial registrationChinese Clinical Trial Registry number, ChiCTR2200062991. Registered on 26/08/2022.

Effects of Ribbed Crossflow Channel in a Turbine Blade on Film Cooling Performance of Diffusion Slot Holes with Various Cross Section Orientations

Abstract This paper investigates the influence of ribbed crossflow on the film cooling performance of a turbine rotor blade. A pressure-sensitive paint measurement technique was employed to measure the effectiveness of film cooling. The discharge coefficients were also measured to determine the flow resistance. A row of film holes was positioned at the pressure surface or suction surface with a spanwise hole spacing of 7.5D, which is half of the rib spacing. The experiments were carried out at a mainstream Reynolds number of 520,000, a turbulence intensity of 3.6%, and a density ratio of 0.97. The crossflow inlet velocity was 45% of the cascade inlet velocity. A fan-shaped hole with a 14 deg expansion angle (Fans-14), a horizontally oriented slot cross section diffusion hole with a 14 deg expansion angle (H1.7-14), and two vertically oriented slot cross section diffusion holes with 14 deg (V1.7-14) and 20 deg (V1.7-20) expansion angles were tested with/without crossflow. The results indicated that the slot cross-sectional orientation significantly changes the flow patterns inside the holes. H1.7-14 has stronger lateral expansion and better surface adhesion, while V1.7-14 and V1.7-20 yield more uniform lateral velocity distributions. Regardless of crossflow, H1.7-14 produces the highest film effectiveness and discharge coefficient on the pressure surface, while it changes to V1.7-20 on the suction surface. The ribbed crossflow increases the film effectiveness on both the pressure surface and suction surface, except for V1.7-20, as it is almost unaffected by the crossflow.

Investigation of the Discharge Coefficient for Laidback Fan-Shaped Holes on Turbine Blades Under Internal Crossflow Condition

Abstract The discharge coefficient of laidback fan-shaped holes on turbine blades under internal crossflow conditions is investigated using experimental and numerical simulation methods. The study is conducted on a linear cascade, with single rows of film holes set on both the pressure and suction surfaces of the test blade, coolant supplied by an internal crossflow channel. The internal crossflow Reynolds number ranged from 39,100 to 78,200, and the pressure ratio ranged from 1 to 1.5. This research considered the effects of internal crossflow Reynolds numbers and hole length-to-diameter ratio on the discharge coefficient of laidback fan-shaped holes. The findings are as follows: internal crossflow increases the inlet loss of film holes and flow separation within the holes, leading to a significant reduction in the discharge coefficient of film holes. Meanwhile, film holes on the pressure surface of the blade exhibit greater sensitivity to crossflow. Under different hole length-to-diameter ratio conditions, the length of the cylindrical section is the primary factor affecting the discharge coefficient, and the magnitude of the discharge coefficient depends on the extent of flow separation within the cylindrical section. The sensitivity of the discharge coefficient to variations in the cylindrical section length decreases once the cylindrical section length exceeds 2.8D for the pressure surface and 2.0D for the suction surface, where the inlet separation region reattaches to the wall. Under plenum conditions, there are significant differences in the discharge coefficients of film holes between the suction surface and pressure surface, especially at pressure ratios below 1.05.

Study on mechanical properties of unsaturated silt in the Yellow River flood area

The alluvial deposits of the Yellow River led to the formation of less clay content, loose soil particles, and low compactness of the unsaturated silt, which makes it complicated to determine the mechanical properties of the Yellow River flood area soil. To investigate the mechanical characteristics of unsaturated silt, the relationship between unsaturated silt saturation and matric suction is analyzed through the soil-water characteristic test, and the soil-water characteristic curve is fitted by the Van-Genuchten model. A series of consolidated undrained shear tests were conducted on silt in Kaifeng using the GDS triaxial apparatus, the influence of moisture content, matric suction (u a-u w), and net confining pressure (σ 3-u a) on the strength characteristics of unsaturated silt was discussed. The results indicated that the net confining pressure, moisture content, and matric suction significantly influenced the shear characteristics of unsaturated silt. The shear strength of unsaturated silt increased with increasing net confining pressure at the same moisture content. The strain-hardening state of silt at high confining pressure was more obvious, while the silt at low confining pressure showed a weak strain-hardening state. Under a constant net confining pressure, the deviatoric stress versus deviatoric strain curves of silt with low moisture content exhibited a strain-softening state, while other moisture content showed a weak strain-hardening state. At the same matric suction, the shear strength increased with increasing normal stress. The cohesion increased and then decreased while the internal friction angle decreased and then increased with the increasing moisture content and matric suction.

Effects of continuous negative pressure suction combined with autologous platelet-rich gel on the levels of CRP, IL-6, wound healing and length of stay in clients with diabetic foot

ObjectiveContinuous passive pressure suction and APG gel therapy effect diabetic foot IL-6, CRP, wound healing, and hospitalization. MethodsClinicopathological data from 102 diabetic foot ulcer patients treated at our institution between March 2018 and May 2022 was examined. Tables generated 51 joint and controlling teams randomly. The observation team received passive pressure suction and APG gel whereas the controlled team received conventional treatment. Teams monitored therapy outcomes, adverse responses, wound healing, hospital stay, and costs. Both teams compared blood uric acid, cystatin C, homocysteine, and serum IL-6, IL-10, and CRP before and after medication. ResultsThe joint team had higher hospitalization costs, shorter stays, and faster wound healing than the controlled team. Diaparity was significant (P < 0.05). The united team worked 100 %, unlike the controlling team. This difference was significant (P < 0.05). Both teams showed significant decreases in CRP, IL-6, and IL-10 levels after therapy (P < 0.05). After therapy, both the combined and controlled teams had substantial differences in blood CRP, IL-6, and IL-10 levels (P < 0.05). Both teams had significantly decreased uric acid, cystatin C, and homocysteine after treatment. The combined team showed significantly decreased uric acid, cystatin C, homocysteine levels following therapy compared to the control team (P < 0.05). ConclusionThe joint team experienced considerably fewer adverse events (3.92 % vs. 17.65 %) than the controls team (P < 0.05). Permanent passive pressure suction and APG gel therapy lower inflammatory response, blood uric acid, cystatin C, and homocysteine, speeding wound healing, reducing side effects.

Influence of suction pressure of clay unsaturated soils on slope stability

Background. The main aspects of the influence of suction pressure on slope stability are considered; an example of calculations in the Plaxis software is presented. Specific features in the behavior of unsaturated and saturated soils are described. A model for describing the behavior of saturated soil under the influence of suction pressure is proposed.Aim. Soviet hydrophysic and soil scientists actively explored the relationship between capillary-sorption (structural or matrix) water pressure in the soil and humidity. However, the introduction of foreign methods and software based thereon into the engineering and geological practice of calculating the stability of slopes has raised the question about the influence of suction pressure of clay soils on the stability of slopes. Materials and methods. The main research material was loams of the Moscow glaciation. Simulation was carried out based on the Muallem — van Genuchten model.Results. The simulation results showed that suction pressure and capillarity directly affect the slope stability coefficient, provided that the similarity of other model parameters.

Flow physics of a subcritical carbon dioxide jet in a multiphase ejector

Existing literature on ejectors, different researchers utilized different turbulence models by their choice, neither analyzing the physics of turbulence nor providing any sufficient optical diagnostics of the flow field. In this article, the physics captured by the Unsteady Reynolds Averaged Navier–Stokes (URANS) and Large Eddy Simulation (LES) are compared based on well-posed boundary conditions obtained experimentally from a carbon dioxide (CO2) vapor compression cycle with an error ≤2.5%. The experimental results utilized for this study are at Reynold’s number (Re) 1.2e5 at the high-pressure inlet (motive flow) maintaining CO2 in subcritical state. The low-pressure inlet (suction flow) is maintained at Re = 9.8e4 with CO2 in vapor state, providing a pressure lift ratio of 1.2 at the diffuser outlet. Comparison of flow topologies with different URANS models reveals that only standard, Shear Stress Transport (SST) k−ω, and Reynold’s Stress Model-Shear Stress Gradient (RSM-SSG) are the suitable URANS models capturing a linearly increasing anisotropy tensor component with increasing strain in the flow. LES also predicted the similar physics. However, standard k−ω overpredicted the suction pressure beyond the acceptable uncertainty limits, which made it inapplicable. For the first time, a spatio-temporal representation of the flow topology with LES revealed the actual jet morphology of a CO2 ejector. Specifically, finger-like structures are key features to entrain more surrounding warm fluid into the colder dense core fluid at the cost of destabilizing and breaking up the jet by stretching the streamwise vortices and obstructing the increase in pressure-lift ratio.

Enhanced cooling performance of blade tip slot cooling: Effect of slot open length

Addressing the critical challenge of thermal load-induced damage in turbine blade tips, this study aims to elucidate the effects of slot open length on film cooling effectiveness (FCE) across turbine blade tips with Pressure Side (PS) and Suction Side (SS) slots considering the application of additive manufacturing to turbine blade tips. Employing a linear cascade setup and the pressure sensitive paint (PSP) technique, we examined and quantified cooling performance across turbine blade tips with PS or SS slots at various slot open lengths. We revealed that while short slot open lengths enhance FCE at the leading edge (LE) due to increased averaged blowing ratios, they fail to adequately cover the trailing edge (TE) region. This decrease in cooling performance is largely attributable to the mixing of coolant with hot gas. In contrast, longer slot open lengths achieve a consistent FCE distribution across the blade tip despite a slight decrease in FCE at the LE region. The study suggests that integrating additional thermal design strategies, such as partition walls with slots, could effectively manage hot gas behaviors, thus enhancing the overall cooling design of turbine blade tips. This research makes a significant contribution to the field of turbine blade tip cooling design, providing insights into optimizing cooling performance through advanced slot configurations enabled by additive manufacturing technologies.

Simulation and experimental study of flexible adsorption and localization mechanism for vegetable grafting machines

Because of the lack of good seedling positioning during vegetable grafting, there are issues such as high labor costs and long grafting time. This article proposes a negative pressure suction seedling positioning method for seed leaves based on the characteristic parameters of cucumber spike wood, and designs a flexible adsorption positioning mechanism for spike wood. Firstly, the ventral surface curve trajectories of cucumber cotyledons were extracted using Matlab software, and then a shape-adaptive design was applied to the attachment surface of the flexible suction positioning mechanism, and a computational fluid dynamics model of the airflow field was established. By combining Fluent simulation analysis with orthogonal experiments, the effect of suction hole diameter, vacuum negative pressure value, suction hole quantity, and suction hole depth on the adsorption effect of the suction head was analyzed, the main and secondary factors and operational indicators that affect the adsorption effect are evaluated. The optimal parameter combination: suction hole diameter of 1.5 mm, vacuum negative pressure value of 2 kPa, suction hole quantity of 42, and suction hole depth of 2 mm, has been found. A verification experiment was conducted on a test bench, and the experimental results show that the success rate of leaf absorption using the optimal parameter combination is 97.69%, which indicates that the suction head is designed reasonably and meets the requirements of grafting.

Three-Dimensional Modeling of Polygonal Ridges in Salt Playas.

In this work, we investigate the formation of the curious polygonal salt ridges that tessellate salt playas worldwide using suitable three-dimensional modeling and simulation of the dynamical processes that are responsible for their formation. We employ the principles of fracture mechanics under cyclic wetting and drying, fluid and mass transport in fracture channels, and processes of crystallization and self-organization to finally replicate the almost Voronoidal pattern of salt ridge mosaics observed in playas. The model is generic and applicable to playas having different salt compositions, as the effect of the salt diffusion coefficient and critical salinity for crystallization are factored in. The final pattern of polygonal salt ridges obtained by simulation visually resembles the geometry of the salt ridges reported in the literature. A single equation describing the time of first crystallization of salt in terms of evaporation suction pressure P, diffusion coefficient D of salt, and relative salinity Δc with respect to critical salinity at saturation, has been proposed. The saturation of crystal growth rate is shown to be a dynamic equilibrium between advection and diffusion processes. We show that the stable polygonal geometry of the salt playas is an effort toward the total minimization of system energy.