Ejection Pressure Research Articles

Scaling the turbulent jet by active pre-chamber

Recently, pre-chamber turbulent jet ignition technology has attracted many attentions as a means of improving combustion efficiency in alternative fuel engines. Pre-chamber engines span a wide range of bore diameters and power outputs, and scaled model experiments based on similarity theory can promote the intensification of research and development for pre-chamber engines with different sizes. While the similarity of turbulent jet development plays the most important role in the entire scaled model experiments, relevant research in this area is scarce. In this paper, for the first time, the theoretical analysis of pre-chamber turbulent jet similarity is carried out based on the similarity theory and gas jet theory. Then, the constant-volume combustion chamber and the high-speed double-pass schlieren imaging are implemented to study the similarity of turbulent jets from two pre-chambers with the orifice diameters of 2.12 mm and 1.50 mm. The results show that controlling the spark timing is an effective method to ensure the same jet ejection timing and pressure building processes during the development of the turbulent jet. Finally, it is found that the jet penetration, jet angle and projection area can be well scaled using the proposed similarity law. These results agree well with the theoretical analysis.

Physiological simulation of atrial-ventricular mechanical interaction in male rats during the cardiac cycle.

Adequate assessment of the contribution of the different phases of atrial mechanical activity to the value of ejection volume and pressure developed by the ventricle is a complex and important experimental and clinical problem. A new method and an effective algorithm for controlling the interaction of isolated rat right atrial and right ventricular strips during the cardiac cycle were developed and tested in a physiological experiment. The presented functional model is flexible and has the ability to change many parameters (temperature, pacing rate, excitation delay, pre- and afterload levels, transfer length, and force scaling coefficients) to simulate different types of cardiac pathologies. For the first time, the contribution of the duration of the excitation delay of the right ventricular strips to the amount of work performed by the muscles during the cardiac cycle was evaluated. Changes in the onset of atrial systole and the delay in activation of ventricular contraction may lead to a reduction in cardiac stroke volume, which should be considered in the diagnosis and treatment of cardiovascular disease and in resynchronization therapy.

Modeling and Experimental Validation of Pre-Chamber Jet Penetration Considering Jet Density and Ejection Pressure Variations

Abstract Although pre-chamber (PC) is regarded as a promising solution to enhance ignition in lean-burn gas engines, a lack of comprehensive understanding of PC jet penetration dynamics remains. This study proposed a zero-dimensional (0-D) model for PC jet penetration, considering the mixing of combustion products and unburned gases and floating ejection pressure. A combustion completion degree was defined employing fuel property and heat release to estimate varying jet density. Pressure differences between PC and the main chamber (MC) were referred to as the ejection pressure. Then, this model was validated against experiments from a constant volume chamber and a rapid compression and expansion machine with CH4-H2 blends at different equivalent ratios. Results showed that the proposed model can provide a good prediction in stationary and turbulent fields with the calibrated model coefficient. The overall jet penetration exhibits a t0.5 dependence due to its single-phase characteristic and the relative lower density compared to ambient gas in MC. The flame propagation speed and heat release in PC influence the combustion completion degree at the start of jet ejection, the mass fraction of burned gas in jet increases with the equivalent ratio. Jet penetration is primarily driven by ejection pressure, with tip dynamics barely affected by the pressure difference after the peak. Tip penetration intensity increases with increased fuel equivalent ratio and H2 addition, owing to the faster flame propagation. These findings can offer useful suggestions for model-based design and combustion model development for gas engines.

Characteristics of Akinetic and Dyskinetic Left Ventricular Aneurysms in the Context of Echocardiographic Diagnosis and Treatment Selection.

Background and Objectives. Distinct pressure curve differences exist between akinetic (A-LVA) and dyskinetic (D-LVA) aneurysms. In D-LVA, left ventricular (LV) ejection pressure decreases relative to the aneurysm size, whereas A-LVA does not impact pressure curves, indicating that the decrease in stroke volume (SV) and cardiac output is proportional to the size of dyskinesia. This study aimed to assess the frequency of A-LVA and D-LVA, determine aneurysm size parameters (volume and surface area), and evaluate predictive parameters using echocardiography in A-LVA and D-LVA. Furthermore, it aimed to compare individual echocardiographic parameters, according to ejection fraction (EF) and SV, with hemodynamic events shown in experimental models of A-LVA and D-LVA and their significance in everyday clinical practice. Materials and Methods. This clinical study included patients with post-infarction left ventricular aneurysm (LVA) admitted to the cardiovascular institute ''Dedinje", Serbia. Echocardiographic volume and surface area of LV and LVA were determined (by the area-length method) along with EF (by Simpson's method). Results. A-LVA was present in 62.9% of patients, while D-LVA was present in 37.1%. Patients with D-LVA had significantly higher systolic aneurysm volume (LVAVs) (94.07 ± 74.66 vs. 51.54 ± 53.09, p = 0.009), systolic aneurysm surface area (LVAAs) (23.22 ± 11.73 vs. 16.41 ± 8.58, p = 0.018), and end-systolic left ventricular surface areas (LVESA) (50.79 ± 13.33 vs. 42.76 ± 14.11, p = 0.045) compared to patients with A-LVA. The ratio of LVA volume to LV volume was higher in the D-LVA in systole (LVAVs/LVESV). The end-diastolic volume of LV (LVEDV) and end-systolic volume of LV (LVESV) did not significantly differ between D-LVA and A-LVA. EF (21.25 ± 11.92 vs. 28.18 ± 11.91, p = 0.044) was significantly lower among patients with D-LVA. Conclusions. Differentiating between A-LVA and D-LVA using echocardiography is crucial since D-LVA causes greater hemodynamic disturbances in LV function, and thus surgical resection of the aneurysm or LV reconstruction must have a positive effect regardless of myocardial revascularization surgery.

Optimization of exhaust ejector with lobed nozzle for marine gas turbine

To attain high-performance ejector configurations, an ejection characteristic testing system was established initially to validate the reliability of the Realizable k-ε turbulent model. Subsequently, optimization investigations were conducted on lobed nozzle ejectors with various structural parameters. The effects of four key structural parameters, including lobed nozzle expansion angle α, lobed nozzle width d, number of lobes in the nozzle n, and height of the square-to-circle section h, were systematically studied. Furthermore, the CRITIC method was employed for multi-objective evaluation to identify the optimal design configuration for the casing ejector. The research findings revealed that among the structural parameters, the lobed nozzle expansion angle α exerted the greatest influence on the ejection coefficient and pressure loss coefficient. The weights of the evaluation criteria were determined by the CRITIC method as follows: ejection coefficient (49.38%) < pressure loss coefficient (50.62%). The optimal design configuration determined by the CRITIC method included α = 45°, d = 150 mm, n = 14, and h = 600 mm. The resulting enclosure design ensures smooth airflow within the system, preventing the backflow of high-temperature mainstream fluid and heating the enclosure. It also maintains a temperature distribution in the typical cross-section that meets specified requirements. Additionally, it facilitates improved mixing of mainstream and secondary fluid and reduces exhaust gas temperature.

Experimental study of scaled-down model ejection water ballistics and two-phase flow of gas and water

There are many factors affecting the hydrodynamic and water ballistic trajectory of vehicles launched underwater, among which the ejection gas pressure, initial motion parameters of the submarine launch platform and the launching water depth have a particularly significant influence. Since it is costly and too long time to carry out a real-size study on the influence of underwater launching parameters, this paper adopts a scaled-down model ejection test to study the evolution characteristics of the flow field of vehicle launched underwater with different ejection pressures and initial ejection angles to reveal the influence of the above parameters on the characteristics of the water ballistics.

Evaluation of the Ejection Pressure for Tracking Internal Cracks during Compaction in Bilayer Tablet Formulations Using Experimental and Finite Element Methods.

This study aimed to evaluate the ejection pressure and the correlation of the findings with the occurrence of internal cracks within bilayer tablets (BLTs) consisting of metformin HCl (MF) and evogliptin tartrate (EG). Then, the mechanism of tablet failure was provided by the finite element method (FEM). The ejection pressure and the difference in diameter depending on MAIN-P were evaluated to understand the correlation between ejection pressure and change in the BLT internal structure. The ejection pressure and the difference in diameter increased as the MAIN-P increased, then steeply decreased from 350 MPa to 375 MPa of MAIN-P, despite there being no pattern in compaction breaking force and porosity. The mechanical integrity at the BLT interface was weakened by internal cracks, reducing ejection pressure. The stress distribution analysis during the compression revealed that crack formation caused by entrapped air located at the center of the BLT interface may not propagate due to concentrated stress, which promotes a tight bond at the edge of the BLT. Furthermore, complete delamination can occur in the ejection process due to localized and intensive shear stresses at the BLT interface. These findings indicate that the mechanisms of internal cracking and delamination were successfully confirmed by FEM simulation. Moreover, measuring ejection pressure before BLT manufacturing can prevent invisible tablet cracks without damaging the tablets.

Discovering the Clinical Relevance of Heart-Lung Interactions.

In 1978, Dr. Pinsky's scientific career became firmly directed toward understanding the deeper meaning of heart-lung interactions. This would define his focus for the next 45 yr. At the time, he and colleagues studied the effects of changes in intrathoracic pressure on left ventricular performance in humans, documenting that the primary effect of large negative swings in intrathoracic pressure was to increase left ventricular transmural ejection pressure, and thus left ventricular afterload, selectively. They concluded that large intrathoracic pressure changes directly influence cardiac performance. This fundamental observation was followed by many additional observations in both highly invasive animal studies supported by less invasive clinical studies, which showed that intrathoracic pressure-induced changes in the gradients for venous return to the heart and left ventricular ejection from the heart disproportionately affected both right ventricular and left ventricular function. The direct clinical implications of these results form the rationale for use of continuous positive airway pressure as a primary treatment of acute cardiogenic pulmonary edema and immediate endotracheal intubation for acute upper airway obstruction. These findings subsequently led to the practical use of dynamic changes in left ventricular stroke volume and the associated arterial pulse pressure during positive-pressure ventilation to identify volume responsiveness and, thus, to personalize resuscitation efforts in the treatment of acute cardiovascular insufficiency.

The Influence of Preparation Parameters on the Morphology and Magnetic Properties of Fe-N Powders Obtained by the Gas Atomization Method

α″-Fe16N2 materials are of increasing interest for their applications in products such as rare earth-free permanent magnets. The lack of a method of mass production for powders as raw materials delays the preparation of such magnets. Through employing the gas atomization method, we managed to prepare α″-Fe16N2 powders whose morphology and magnetic properties were tailored by the preparation parameters. As a result of optimizing the preparation parameters (ejection temperature and pressure, ejection nozzle diameter, and atomization pressure), we managed to prepare powders with a size of about 30 μm and a content of 31% α″-Fe16N2 phase. The value of the saturation magnetization (234.8 emu/g), the reasonable coercivity value (970 Oe) presented by the prepared powders, and the opportunity of scaling up approaches based on the preparation of powders via gas atomization support the feasibility of preparing α″-Fe16N2 powders at an industrial level.

Peculiarities of drilling hard rocks using hydraulic shock technology

Purpose. To test the theoretical provisions for calculating the geometric and gas-dynamic parameters of a hydropulse apparatus for strikers using core pipes. Methodology. The research methodology is based on the tests carried out. The tests were conducted between January 6, 2021, and April 28, 2021. The type of test is laboratory bench trials. In the course of the study, methods of synthesis and analysis of information were applied. Finding. The basic design parameters of a hydro-pulse generator capable of operating efficiently with impact machines were obtained during the bench research. The optimal scheme of air flow distribution at the exhaust of the hydraulic hammer has been established. The optimal value of the pressure drop in the operating and blocking modes of operation of the generator is determined. In addition, the optimal value of the ejection coefficient in these two modes of operation of the generator was determined. Originality. The article investigated the technologies of drilling hard rocks in order to optimise the basic geometric parameters of the hydraulic pulse generator, to distribute the working flow in front of the jet blower, to measure the value of the ejection coefficient and pressure drop to clarify the composition and methodology of experiments in borehole conditions. Practical value. The presented study can be used to optimise the drilling technology as well as a basis for training specialists in the field of hard rock drilling using hydraulic percussion technology.

Novel approaches for left atrial pressure relief: Device-based monitoring and management in heart failure.

The importance of the left atrium (LA) has been emphasized in recent years as the features of heart failure (HF), especially with regard to variability in patient and pathology phenotypes, continue to be uncovered. Of note, among the population with HF with preserved ejection fraction (HFpEF), pressure or size of the LA have become a target for advanced monitoring and a therapeutic approach. In the case of diastolic dysfunction or pulmonary hypertension, which are often observed in patients with HFpEF, a conventional approach with clinical symptoms and physical signs of decompensation turned out to have a poor correlation with LA pressure. Therefore, to optimize HF treatment for these populations, several devices that are applied directly to the LA have been developed. First, two LA pressure (LAP) sensors (Heart POD and V-LAP Device) were developed and may enable patient self-management remotely with LAP-guided and physician-directed style. Second, there are device-based approaches that aim to decompress the LA directly. These include: (1) interatrial shunt devices; (2) left ventricular assist devices with LA cannulation; and (3) the left atrial assist device. While these novel device-based therapies are not yet commercially available, there is expected to be a rise in the proposition and adoption of a wider range of choices for monitoring or treating LA using device-based options, based on LA dimensional reduction and optimization of the clinically significant pressure relief. Further development and evaluation are necessary to establish a more favorable management strategy for HF.

ИЗУЧЕНИЕ ТЕХНОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК СУБСТАНЦИИ VMA-10-13 И ТЕХНОЛОГИЯ ИЗГОТОВЛЕНИЯ ТАБЛЕТОК

Abstract. Currently, intensive research is being conducted in the study of new biologically active substances for medical use that will be effective and safe for human use. Before the production of a medicinal product, the technological parameters and characteristics of a pharmaceutical substance must be carefully studied and scientifically substantiated. When creating and modernizing the technology of dosage forms, one of the most important stages is the assessment of bioavailability. It, in turn, depends on the physico-chemical properties of the active substance. The present work is devoted to the study of the technological properties of the original pharmaceutical substance of the quinazoline derivative, used as an active substance for the development of the composition and technology for obtaining a dosage form for oral use in the form of tablets using solid dispersion. The technological characteristics of a new biologically active compound –a derivative of quinazoline: 3-[2-(2-Methylphenylamino)-2-oxoethyl]-quinazoline-4(3H)–oh (laboratory code: VMA–10–13), capable of influencing pharmacological activity in the production of the dosage form, have been studied. The study examined key indicators: residual moisture, bulk density, flowability, ejection pressure, compressibility and disintegration of model tablets. The composition and technology of obtaining a solid dosage form (tablets) using a solid dispersion with improved biopharmaceutical characteristics have been developed. The main pharmaceutical and technological indicators of tablet quality are determined: average weight and disintegration. The data obtained allowed us to assume the content and course of further stages of pharmaceutical development.

Measuring Liquid Droplet Size in Two-Phase Nozzle Flow Employing Numerical and Experimental Analyses.

The flavoring process ensures the quality of cigarettes by endowing them with special tastes. In this process, the flavoring liquid is atomized into particles by a nozzle and mixed with the tobacco in a rotating drum. The particle size of the flavoring liquid has great influence on the atomization effect; however, limited research has addressed the quantitation of the liquid particle size in two-phase nozzle flow. To bridge this research gap, the authors of this study employed numerical and experimental techniques to explore the quantitative analysis of particle size. First, a simulation model for the flavoring nozzle was established to investigate the atomization effect under different ejection pressures. Then, an experimental test is carried out to compare the test results with the simulation results. Lastly, the influencing factors of liquid particle size in two-phase nozzle flow were analyzed to quantify particle size. The analysis results demonstrated that there was a cubic correction relationship between the simulation and experiment particle size. The findings of this study may provide a reliable reference when evaluating the atomization effect of flavoring nozzles.

RATIONALE OF THE COMPOSITION OF THE TABLET MASS FOR THE CREATION OF DISPERSIBLE TABLETS WITH BIOFLAVONOIDS

Abstract. In recent years, with diseases associated with chronic venous insufficiency, people have resorted to medications created on the basis of bioflavonoids and flavonoid complexes. However, most oral phleboprotectors, including flavonoids such as rutin, hesperidin, diosmin, have low biological availability, which is due to their low solubility in water. It is possible to increase bioavailability by using substances with a higher degree of micronization, as well as by complexing and using dosage forms with increased bioavailability. In this regard, the purpose of this work was to create a drug in the form of dispersible tablets containing rutin and hesperidin in combination with ascorbic acid as active components. Substances of rutin and hesperidin, ascorbic acid, a PE-5300V spectrophotometer, a stopwatch, scales, buckets, a manual press with pressure gauges of various sensitivity, a tablet press RTM-12, punches and a matrix with a diameter of 10 and 20 mm were used in the work. To determine the main indicators of tablet mixtures for dispersible tablets, 6 model compositions of tablet mixtures with different contents of gas-forming components, fillers, binders, moisture stabilizers, lubricants and flavor additives were made. In the course of a step-by-step study of technological, physico-chemical and organoleptic indicators of 6 model formulations, the approximate composition and technology of dispersible tablets were selected. The obtained results were recalculated taking into account the ranking of the measurements made. The integrated weighted average assessment of disintegration, crushing strength, ejection pressure, moisture resistance, organoleptic properties and sedimentation stability made it possible to select the final composition of the dispersed tablets. It is established that the maximum weighted average score belongs to the dispersed tablets obtained from tablet mixture No. 6.

Effects of electrode cross-sectional shape and machining fluid ejection pressure on small hole EDM

Effects of electrode cross-sectional shape and machining fluid ejection pressure on small hole EDM

Endothelial function and adaptive capabilities of adolescent adolescents with arterial hypertension

Summary. The article is devoted to the study of the state of vascular reactivity, morphofunctional parameters of the heart and adaptive capabilities in adolescents with arterial hypertension. The goal is to study the the state of endothelium-dependent vasodilation and determine the adaptive capabilities of boys with arterial hypertension without metabolic risk factors, depending on the presence of endothelial dysfunction. The study included 22 boys with arterial hypertension aged 13-17 years, 10 of them had endothelial dysfunction on a sample with reactive hyperemia. The study included clinical examination, anthropometry, ECG, EchoCG, functional tests (Ruffier, klinoorthotest). Serum total cholesterol levels were also assessed. Statistical analysis was performed using the program s / n SPSS 17 4a 180844250981. Results. It was found that 58.4% of boys with arterial hypertension had endothelial dysfunction without metabolic risk, which in most cases combined with reduced exercise tolerance and insufficient physical activity. In such adolescents, in comparison with peers with hypertension and normal endothelial function, higher growth, a high frequency of dolichomelia, an increase in the ejection fraction and pressure in the left atrium are noted, indicating an increase in the pumping function of the left ventricle. The frequency of registration of endothelial dysfunction was not substantially correlated with the type of vegetative support for activities in children with arterial hypertension. However, in 60% it was registered against insufficient sympathoadrenal supply - asympathicotonic and hyperdiastolic variants of the klinoorthotest. The presence of endothelial dysfunction is recorded in more than half of adolescents with arterial hypertension. Higher ejection fraction and pressure in the left atrium during systole, which are determined in patients with arterial hypertension and insufficient vasodilation with a decrease in heart rate reflect adaptive changes in the functioning of the myocardium with a deterioration in endothelial function.

Analysis of the main factors affecting mass production in the plastic molding process by using the finite element method

Plastic injection molding is widely used in many industrial applications. Plastic products are mostly used as disposable parts or as portable parts for fast replacements in many devices and machines. However, mass production is always adopted as an ideal method to cover the huge demands and customers’ needs. The problems of warpage due to thermal stresses, non-uniform pressure distribution around cavities, shrinkage, sticking and overall products quality are some of the important challenges. The main objective of this work is to analyze the stress distribution around the cavities during the molding and demolding to avoid their effects on the product quality. Moreover, diagnosing the critical pressure points around and overall the cavity projection area, which is subjected to high pressure will help to determine the optimum pressure distribution and ensure filling all cavities at the same time, which is another significant objective. Computer-aided design (CAD) and CATIA V5R20 are adopted for design and modeling procedures. The computer-aided engineering (CAE) commercial software ABAQUS 6141 has been dedicated as finite element simulation packages for the analysis of this process. Simulation results show that stress distribution over the cavities depends on both pressure and temperature gradient over the contact surfaces and can be considered as the main affecting factor. The acceptable ranges of the cavity stresses were determined according to the following values: the cavity and core region temperature of 55–65 °C, filling time of 10–20 s, ejection pressure 0.85 % of injection pressure, and holding time of 10–15 s. Also, theoretical results reveal that the uniform pressure and temperature distribution can be controlled by adjusting the cavities layout, runner, and gate size. Moreover, the simulation process shows that it is possible to facilitate and identify many difficulties during the process and modify the prototype to evaluate the overall manufacturability before further investing in tooling. Furthermore, it is also concluded that tooling iterations will be minimized according to the design of the selected process

Effects of initial conditions on MILD combustion for diesel in a constant pressure combustion bomb

The experimental and computational studies for MILD combustion of diesel were conducted in this paper. The experiment was carried out in a constant pressure bomb and the computation was completed with the SAGE combustion model. The initial condition in the experiment covers two temperatures (723 K and 773 K), two pressures (18 bar and 25 bar), with a constant fuel flow of 2 kg/h, an oxygen flow of 1 kg/h, and a wide range of carbon dioxide flow containing 35–160 kg/h. Normal combustion has bright yellow flame and MILD combustion has blue flame according to observation in the experiment. The effects of ejection ratio, initial temperature and pressure are investigated to illustrate the mechanism of MILD combustion. The results show an increase in ejection ratio and an increase in initial temperature are propitious to achieve MILD combustion, while increased pressure needs more strict requirements to realize MILD combustion. Generally, experiment results and computations have similar trends for the effects of initial conditions on MILD combustion.

Study on the dust removal and temperature reduction coupling performances of magnetized water spray.

Dust pollution and heat damage hazards are important problems affecting underground safety production. This paper is aimed at exploring the optimal magnetization conditions of magnetized water for dust removal and temperature reduction and improving the utilization rate of water. First, the surface tension, viscosity, and specific heat capacity of water under different magnetization conditions were measured experimentally. Then, the influence law of ejection pressure on spray atomization and the changes of dust removal performance before and after magnetization of water were analyzed. Based on this, the temperature reduction effect of magnetized water under different wind speeds was analyzed, and the magnetization conditions with the best coupling performance of magnetized water were obtained. Finally, a spray system was designed to control the magnetization conditions strictly. The results demonstrate that the dust removal performance is better when the magnetic field intensity is 150 mT and the magnetization time is 80 s. Under this condition, the specific heat capacity also reaches the maximum. These research results can provide a theoretical basis for the selection of dust pollution and heat damage control measures in mines.

Comparison of hyaluronic acid filler ejection pressure with injection force for safe filler injection.

Owing to the increase in the number of medical procedures performed every year, the frequency of filler injection-related complications has also increased. Although slow, gentle injections with low pressure are usually considered to be safe, the differences in ejection pressure during a filler injection remain to be determined. This study aimed to identify the optimal pressure during filler injections and evaluate its capacity to overcome the arterial blood pressure and reflux the filler material. Twelve combinations of four hyaluronic acid (HA) fillers with different rheological properties and three needles of different diameters were assessed to determine the force exerted by the injection model. The ejection forces corresponding to varying injection forces were measured and HA filler ejection pressures were calculated. The highest and lowest injection forces were achieved using 30- and 25-G needles, respectively. In accordance with the expected ejection force, high ejection pressure was achieved by administering the HA filler under a high injection force. Irrespective of the injection force, the ejection pressure was likely to be higher than the vascular pressure at the time of entry into the vessel, rendering the injection dangerous. During filler injection, penetration of blood vessels and intravascular injection can be avoided by approaching the target area gently using a cannula or needle.