Piston Type Research Articles

Доклинические испытания отечественных устройств, применяемых при внегоспитальной остановке кровообращения

Summary. The aim of the study was to evaluate the effectiveness of domestic devices for supporting blood circulation in case of out-of-hospital circulatory arrest during preclinical trials. Research materials and methods. The study assessed the effectiveness of the Russian cardiac massager “CardioRobot” – an automated device for performing indirect cardiac massage of domestic design. This device has the following technical characteristics: piston type design; compression depth – (50-60±2) mm; compression frequency – (102±2) compressions/min; 2 operating modes – continuous and 30:2; weight – 6.5 kg; continuous battery life – 45 min; trapezoidal compression curve. To evaluate the device, a comparative experiment was conducted on large mammals (pigs), during which the work of the domestic prototype and the foreign device “LUCAS-2” was compared by comparing the indicators of central hemodynamics and gas exchange. During the clinical trials of LifeStream ECMO, postmortem extracorporeal membrane oxygenation (ECMO) of two donors was performed. During the experiment, the following were assessed: pO2, pH, pCO2, arterial blood lactate and creatinine concentrations. Research results and their analysis. During preclinical trials, domestically produced devices demonstrated experimental effectiveness comparable to similar foreign-made products. Currently, the LIFESTREAM ECMO perfusion emergency circulatory restoration complex for human resuscitation has received a certificate and is actively used in the Russian Federation, and the CardioRobot automated chest compression device is undergoing state registration.

Theoretical Model Development and Mixed Lubrication Analyses of Rolling Piston Type Rotary Compressors: A Review

Owing to the requirements for high performance and long life, the friction and wear problems of rolling piston type rotary compressors have drawn much attention. Various theoretical models have been developed and improved to reveal the inner state of the compressor and obtain the optimization schemes. However, there remain some disadvantages and research gaps in the corresponding modeling and mixed lubrication analyses, and a comprehensive summary is lacking. To have a better understanding of the research status, this paper reviews the theoretical model development and mixed lubrication analyses of the compressor in the past decades. The determination of compression pressure, the modeling process of moving components, and the key findings are presented in detail. On this basis, some important influencing factors and the problems remaining to be solved are also discussed. This paper provides multifaceted guidance for manufacturers and researchers to conduct further theoretical analysis and optimal design.

Effect of knock on piston thermal load of a high compression ratio natural gas engine based on stepwise decoupling calculation

High compression ratio natural gas engine (NGE) is prone to knock at high load, which aggravates the thermal load of piston. Therefore, accurately evaluating the piston thermal load in the practical design is essential to enhance engine reliability and improve performance. The typical piston thermal load simulation adopts uniform wall boundary conditions, making it difficult to reveal the influence of turbulent flame and knock on the piston thermal load. In this paper, a stepwise decoupling method is applied to calculate the piston thermal load. The advancement of this method lies in its integration of chemical reaction mechanism with computational fluid dynamics (CFD) to calculate the spatial variations in heat transfer coefficient (HTC) and near-wall gas temperature at the piston top. Moreover, the conjugate heat transfer (CHT) method is adopted to solve the piston thermal load by coupling the thermal boundary conditions (TBC) obtained in the first step with the cooling oil boundary conditions. Based on this method, the effect of knock on piston thermal load of a high compression ratio NGE under different knock intensities is explored in this paper. It is found that turbulent combustion causes uneven distribution of thermal load at piston top. The decrease in knock intensity significantly reduces the gas temperature, heat flux and thermal load at piston top. Particularly under severe knock, the average temperature of piston is 22.9 K and 32.4 K higher than that of light knock and normal combustion, respectively. Furthermore, the main factor affecting the piston temperature field distribution is the gas temperature rather than the HTC. The gas temperature at piston top is overall the highest on the side near the inlet valve pit, which leads to a higher temperature on this side. Compared to light knock and normal combustion, when severe knock occurs, the thermal load on the exhaust valve pit increases significantly. This study provides an effective method for analyzing the heat transfer of the piston under knocking combustion, which is of guiding significance for controlling the thermal load of the high-temperature components in the combustion chamber.

The Effects of the Initial Geometrical Errors on the Piston Friction and Sealing Performance in a Buoyancy Regulator of an Underwater Glider

Abstract As an important power component of an underwater glider, the energy consumption of the buoyancy regulator directly affects the endurance of the underwater glider. The accurate calculation and prediction methods for the friction forces can be helpful for improving the working performance of the buoyancy regulator. The traditional friction prediction models consider the cylinder as perfect cylinder without any geometric error, which cannot accurately reflect the effects of the initial geometric defects on the friction force and sealing performance of the cylinder of the piston type buoyancy regulator. This article proposes a new friction force calculation method considering the initial geometrical defects of the cylinder. By using the theoretical analysis and finite element calculations, the effects of the initial geometrical defects on the friction force and sealing performance of the piston type buoyancy regulator can be more accurately analyzed. The effect of the ovality and taper on the friction force and sealing performance is analyzed. In addition, the friction force calculation method proposed in this article is validated by an experiment. This article can provide an accurate cylinder friction force calculation method considering the initial geometrical errors for the piston type buoyancy regulators.

Investigation on improving the multi-operating condition performance of a rotary compressor based on variable stiffness valve

Improving valve design is crucial for enhancing the performance of rolling piston type rotary compressor. A novel variable stiffness valve based on PEEK and stainless steel was proposed. The stress-strain behavior of the novel valve was studied, and its operational characteristics, including opening and closing angles and over-compression losses, were analyzed in a compressor. It is shown that opening and closing angle of the new-designed valve were advanced compared to that of the original cylinder by about 2∼3°, leading to a general reduction in over-compression losses, with a maximum decrease of 4.15 W. The impacts of new-designed valve on compressor performance were experimentally investigated. The cooling capacity and coefficient of performance of compressors equipped with new-designed compared to original valve were improved by 1.1–1.7 % and 1.1–2.6 %, respectively. In addition, the input electrical power required for the new valve was observed to be 0.9–1.3 % lower. The incorporation of high-damping material in the new valve design significantly reduced compressor noise by 3–5 dB at the critical frequency bands of 630–1250 Hz. These findings offer valuable insights for enhancing the energy efficiency and noise reduction in rolling piston type rotary compressors.

Effect of over-expansion in a cycloidal rotary engine

An over-expanded (Atkinson cycle) reciprocating internal combustion engine is a crucial component of hybrid and range-extended electric vehicles. The realization of the over-expansion cycle with high efficiency in novel power devices with a compact, simple design, such as cycloidal rotary engines, is a promising alternative. The cycloidal rotary engine is an internal combustion engine that operates four strokes without a reciprocating mechanism and valve train. The over-expansion cycle is implemented in the cycloidal rotary engine by asymmetrical intake and exhaust port arrangements, resulting in open and closure timings. This study aimed to establish inherent characteristics of the over-expansion cycle in gasoline-fueled rotary engines with spark ignition. A numerical simulation of the gas exchange and combustion process in a wide range of over-expansion ratios was conducted. It was concluded that the over-expansion cycle is realized without typical piston engine methods such as variable valve timing and multilink mechanism. The thermal conversion efficiency is a peak function of the over-expansion ratio. In the over-expansion range of 1.1–1.2, the thermal conversion efficiency of the cycloidal rotary engine increased up to 32.7–34.5%. The benefits of fuel economy and carbon oxide emission can also be achieved within the specified range of over-expansion ratio.

Microstructure and Mechanical Characteristics of Friction Welded Joint between Alumina and Aluminum Casting Alloy

In this study, the Al2O3 round bar and Al-Si12CuNi (AC8A) round bar were joined by friction welding. AC8A is a typical piston material treated by the heat treatment T6. The parameters of the joining condition are friction time and upset pressure. SEM observed the microstructure at the interface region of joined materials. 1) Judging from these photographs, the damages to the microstructures at the interface region of joined materials by upset pressure are more significant than those caused by friction time. 2) The relationship between the joint conditions and mechanical characteristics from three points of bending test results for the joint material specimens. 3) The residual stresses around the interface were measured by the Raman spectroscopy method. There is a possibility that the friction welding conditions are correlated to the residual stresses.

Experimental and numerical analysis of heat transfer mechanisms for two-phase oil-refrigerant flow process in the cylinder of rotary compressor

Investigating the heat transfer mechanisms in rolling piston type rotary compressors is crucial for improving their operational efficiency. A thermal test platform was established and steady-state temperature fields of key components were measured under various conditions, revealing a correlation between these temperatures and crank angles, except near the angle of 54° for the cylinder head-up. It provided important boundary conditions for simulation research. A novel three-dimensional fluid–solid-heat coupled simulation method was proposed, calculating heat transfer coefficients at fluid–solid interfaces. The two-phase heat transfer characteristics post oil–gas miscibility was studied, arising from the injection of lubricating oil into the working chamber. Two-phase oil-refrigerant mixtures, compared to single-phase refrigerant, increased heat transfer coefficients by 2.35 % in the suction channel and 2.99 % in the cylinder head-up, but decreased by 5.85 % in the cylinder head-down, 17.42 % in the piston, and 5.63 % in the cylinder. Oil injection was found to significantly enhance convective heat transfer in the suction chamber, increasing suction superheat in the cylinder by up to 29 K and reducing temperature of the compression chamber by up to 17 K. These results provide novel insights into the complex heat transfer in rotary compressors.

Analisa Komparasi Sifat Fisis dan Mekanis Piston Sepeda Motor dari Empat Pabrikan

The piston is an essential component in the internal combustion system. Unfortunately, most piston products on the market are of low quality, which is detrimental to consumers. Most pistons sold in spare parts shops in Medan City have varying prices and different quality. The study compares four manufacturers' chemical composition, microstructure and hardness of the pistons of 4-stroke motorcycles. The four types of pistons were purchased at an automotive component sales shop in Medan city. The pistons were cut by machine and then analyzed for chemical composition, microstructure and hardness. The research results show that the chemical composition of the four-piston manufacturers is almost similar, where the silicon content ranges from 2-3%, which is a hypoeutectic Al-Si aluminium alloy. Interestingly, the hardness values and microstructure of pistons are different. The hardness value for brand X is the highest compared to other products, at 41.16 VHN. Microstructural observations show that the microstructures of manufacturers W, X and Y are similar, where the Si particles are evenly distributed with almost uniform sizes. Meanwhile, the Z manufacturer shows a microstructure with fibrous Si particles with a coarse SDAS size.

The hydrodynamic study of the interaction between waves and objects in permeable reef environment

This study employed a self-developed viscous numerical wave tank based on the piston type wave maker and user-defined functions of Fluent software to explore the wave shadowing effect of the transmission of waves near the underwater object and the reef. In the study, various factors such as the permeability of the reef, changes in topography, and objects motion were considered, and detailed simulation analyses were conducted for five scenarios: a solitary reef, a fixed underwater object, a forced moving underwater object, and a free moving underwater object. The results showed that this method can effectively simulate the complex flow field changes around the underwater object and the reef under different conditions, while also fully considering the strong nonlinearity and fluid viscosity effects between the wave surface and the object. Furthermore, it was found that between the free-moving object and the reef, there would be significant swirls and streamline distortion. This indicates that a portion of the incident wave energy is transformed into kinetic energy of swirls, resulting in a smoother and more uniform flow field and reducing wave forces.

Pengaruh Bentuk Permukaan Piston Rata (Flat) Dan Piston Cembung (Dome) Terhadap Performa Dan Emisi Gas Buang Pada Mesin Sport 200cc

The aim of this research is to determine the effect of engine performance (torque and power), as well as exhaust emissions after replacing the piston. Tests were carried out on a 200CC engine with flat piston specifications with a diameter of 65.0 mm and replaced with a convex piston with a diameter of 65.0 mm using pertalite fuel. The research results obtained by replacing the convex piston (dome) caused the volume of the combustion chamber to decrease resulting in increased torque and power. There was an increase in torque of 0.02607 ft-lbs and an increase in power of 41.95384 HP, then the compression ratio increased by 0.5%. In exhaust gas emissions containing CO, HC, O2, CO2 using a gas analyzer with the results of research on flat pistons and dome pistons, it can be seen that emissions from convex pistons (dome) have increased compared to flat pistons. with the highest increase in stationary of 6.17% in CO emission content due to incomplete combustion residue, which means that the type of piston has a significant influence on exhaust gas emissions. Then the exhaust gas emission test results also show an increase in the O2 emission content on the flat piston at RPM 5000 with a value of 4.24% due to the mixture of oxygen and fuel being more perfect, but on the convex piston (dome) there is a significant increase Compared to a flat piston only at RPM 6500 with a value of 4.53% in O2 emission content. The HC and CO2 emissions content shows unstable or changing values. Apart from that, variations in engine speed also affect the exhaust emissions produced.

Karakteristik Semburan Bahan Bakar Aviation Gasoline dengan Nozzle Pesawat Cessna 172S

Avgas fuel is fuel from aviation engines, namely piston engine type aircraft, where the spray of this fuel is very influential on the life of a piston type aircraft engine. The characteristics of avgas fuel bursts, namely the distance, temperature and shape of the spray, are rarely studied in Indonesia, so with using experimental and varied data collection techniques, we obtained the characteristic results of the avgas type fuel spray and its mixture, where the mixture of 20% ethanol with a distance of 21 cm at a pressure of 3 bar is the lowest point of the fuel mixture spray temperature, namely reaching 15oC, the effect of The mixture of fuel with ethanol means spots on the walls and combustion chamber due to the mixture of alcohol containing water so that traces and water spots can become crust on the combustion chamber.

ANALYSIS OF THE POSSIBILITY OF APPLICATION OF HYDRAULIC MOTOR-WHEELS IN TRANSMISSIONS HIGH-SPEED TRACTORS

Goal. The purpose of the article is to assess the possibility of developing a hydraulic fluid power in accordance with the standard traction-speed characteristics of the KhTZ-17021 wheeled tractor with the of using gearless drives of the driving wheels. For this purpose, the calculation of the hydraulic fluid power of the wheeled tractor was performed when using the latest radial piston multi-cycle hydraulic motor-wheels with a wide range of rotation frequency and adjustment of the working volume. Research methodology. An analysis of the traction-speed characteristics of the KhTZ- 17021 wheeled tractor and, based on it, a review of modern high-torque radial-piston multi-cycle hydraulic motors from the point of view of meeting the characteristics of torque and rotation frequency with power limitations relative to the serial model in the full speed range of the tractor. The maximum values of the working volumes of the 4 driving hydraulic motor-wheels and the power supply pump of these hydraulic motors, the torque and pressure drop in the hydraulic drive are calculated, and the modes in which it is necessary to change the working volume of the hydraulic motors from the maximum to the minimum values to work out the traction-speed characteristics. A comparative analysis of radial-piston multi-cycle hydraulic motors was carried out, and for the hydromotor-wheel model MHP27 of the "Poclain Hydraulics" company, which was chosen for the study, the hydraulic principle diagrams were considered with the use of a hydraulic regulation system of four stages of the working volume in hydraulic motors, the use of combined parking and service brakes, as well as an anti-skid system using means of proportional electro-hydraulic automation. The results. High-torque hydraulic motor-wheels of the radial piston type were selected, which make it possible to ensure the operation of the tractor transmission without intermediate gearboxes between the hydraulic motors and wheel hubs, and the calculated value of the working volume of the axial piston pump, which ensures the operation of the tractor transmission in the full speed range. Based on the results of the calculations, it was established that the pressure in the hydraulic drive does not exceed 35 MPa, while values from 40 MPa to 50 MPa are achieved in modern pumps and hydraulic motors. The possibility of increasing the speed of the tractor from standard 35 km/h to promising 50 km/h is shown.

Performance and energy balance analysis of the downsized SI engine with using a novel OPCVCR and synchronized twin spark plugs configurations

Recently, the exhaust emissions become one of the main issues in the downsizing spark ignition (SI) engine. It is necessary to develop clean combustion and high efficiency SI engines for further increasing the performance and brake thermal efficiency. In this study, a novel opposite piston type continuous variable compression ratio (OPCVCR) mechanism combined with synchronous twin spark plugs configurations was proposed and applied in the turbocharged downsizing SI engine. The purpose of this study was to propose a novel type of OPCVCR engine and analyze its combustion, performance and energy balance characteristics. The results showed that the peak combustion temperature (PCT) and peak combustion pressure (PCP) of the OPCVCR engine with twin spark plugs were increased when the compression ratio (CR) increased. The knocking combustion intensity of the downsized SI engine was increased when the CR increased, while the knocking combustion intensity can be alleviated effectively by introducing the external EGR. In addition, the energy utilization efficiency was increased with increasing the CR of the OPCVCR engine with twin spark plugs. Besides, the indicated specific fuel consumption (ISFC) of the base downsized SI engine could be decreased by 23.59% and the indicated thermal efficiency (ITE) of the base downsized SI engine could be increased 21.62% by adopting CR 16 and introducing 10% external exhaust gas recirculation (EGR), respectively.

Effects of hydrothermal alteration on shear localization and weakening in the mantle lithosphere

Hydrothermal alteration occurs in upper-mantle fault zones and significantly modifies the rheological properties of ultramafic rocks. To understand how hydrothermal alteration affects shear localization and the strength of the fault zones, we conducted simple-shear deformation experiments on water-saturated harzburgite (70 wt% olivine +30 wt% orthopyroxene) gouges sandwiched between three types of shear pistons (tungsten, yttria-stabilized zirconia, and corundum) using two deformation-DIA apparatuses at confining pressures of 1–4 GPa, temperatures of 500–580 °C, average shear strain rates of 6.1 × 10−6 s−1 to 1.0 × 10−4 s−1, and water contents of 4–30 wt%. The harzburgitic gouges with water contents of 10 and 30 wt% exhibited steady-state sliding or strain-hardening behavior, and the shear strength of the latter sample was less than one-third of that of the former sample, possibly reflecting the difference in pore fluid pressure. Olivine/orthopyroxene grains exhibit distributed microfracturing and grain rotation towards P foliation, indicating the operation of cataclastic flow. Shear displacement is also accommodated by the development of serpentine- or talc-bearing multiple shear zones including B, R1, and/or Y shears, where intense cataclasis-related grain size reduction and dissolution/precipitation occur. For experimental runs using tungsten and zirconia shear pistons, the serpentine or talc blades that wrap finer-grained and dissolved olivine/orthopyroxene grains form an interconnected network, indicative of frictional sliding or dislocation glide on their basal planes as a dominant deformation mechanism. Raman spectra of the serpentine minerals indicate that they represent antigorite with low crystallinity. These findings suggest that when deep lithospheric fault zones undergo hydrothermal alteration, deformation is controlled by competition between cataclastic flow in olivine/orthopyroxene matrix and slip or glide of antigorite or talc in semi-brittle fault zones, the predominance of which depends on the amount of the hydrous phyllosilicates and the magnitude of pore fluid pressure.

Effect of Split and Re-Entrant Type Piston Bowl Geometry and Preheated Calophyllum Inophyllum Methyl Ester on the Conventional CI Engine Performance

Effect of Split and Re-Entrant Type Piston Bowl Geometry and Preheated Calophyllum Inophyllum Methyl Ester on the Conventional CI Engine Performance

Study on the production law and optimization parameters of CO2 huff ‘n’ puff for continental shale oil

AbstractIn this study, nuclear magnetic resonance and computed tomography scanning were used to analyze the production law and displacement mechanism of Jimusaer continental shale oil during CO2 huff ‘n’ puff, and the optimal parameters were determined. The results indicated that CO2 huff ‘n’ puff mainly produces crude oil in pore throats with 0.1–1 μm radii, while crude oil in pore throats with radii below 0.1 μm cannot be produced. Multiple CO2 huff ‘n’ puff cycles can connect fluids in fractures with fluids in large–medium pore throats, eliminate fracture effects on the oil recovery factor, and achieve coefficient development of both fractured and unfractured shales. In the CO2 huff ‘n’ puff process, core pressure change could be divided into three stages of injection–holding–depletion, and the oil displacement mode was the piston type. The study of huff ‘n’ puff parameters revealed that huff ‘n’ puff cycles and injection pressure have a great influence on the CO2 huff ‘n’ puff efficiency, while the injection timing and soaking time imposed relatively small effects. For continental shale in the Jimusaer Sag, the optimal CO2 huff ‘n’ puff parameters are five cycles, 4‐MPa injection timing, 25‐MPa injection pressure, and 12‐h soaking time.

CFD based modeling of OWC device positioned over stepped bottom

This research deals with various parameters associated with the hydrodynamics of an OWC device positioned over the stepped bottom. The problem is solved using the multiphase based CFD technique in “ANSYS Fluent software”. A “piston type wavemaker” and dynamic meshing technique are employed to produce the incident wave inside the numerical wave tank (NWT). Further, “volume of fluid” procedure is implemented to produce the free surface in the NWT. The “free surface elevation” is analyzed in various instant of time. Contour plots of the dynamic pressure, turbulent kinetic energy and turbulent intensity associated with the fluid motion are provided. Further, the variation of the vertex average total pressure and vertex average y− velocity at the orifice on the OWC device’s top wall are analyzed with respect to flowtime.

Importance of Diameter of Long Process of Incus in Stapedotomy-New Findings From In Vivo Study.

Introduction Stapes surgery for otosclerosis is a precise surgical procedure. To achieve excellent hearing results, a firm and stable attachment of the prosthesis to the long process of incus (LPI) is necessary. The present study provides details on the attachment site in two dimensions to choose an appropriate prosthesis and to ensure firm attachment for better surgical outcomes. Objective To study the diameter of the LPI and its relevance in determining the piston, used in stapes surgery by an in vivo method. Methods This study was conducted in 41 patients who underwent stapedotomy, where both Anteroposterior (AP) and Mediolateral (ML) diameters of the LPI were measured at the site of attachment of the piston using specially designed instruments, intraoperatively. Radiological data were obtained to measure the LPI diameter from the normal ears of 46 patients. It was measured from both the right and left side, hence 92 LPI diameters were obtained. Results The most commonly used site for prosthesis attachment is between 1-1.5 mm away from the tip of the LPI. We found great variability in the diameters of LPI in the attachment site, with the AP diameter ranging between 0.6 -1.5mm and the ML diameter ranging between 0.5mm-1.2 mm. Conclusion Pistons by design have characteristics of gripping incus that will vary between types. Based on LPI dimensions, ideal piston types with appropriate inner loop diameters are suggested in this study. HRCT before surgery should include measurements of the LPI as a guide to the choice of the prosthesis during surgery.

Co-optimization of operating parameters, fuel composition, and piston bowl geometry of gasoline compression ignition (GCI) engine at high loads

Focusing on the gasoline compression ignition (GCI) combustion mode, the operating parameters, fuel composition, and piston bowl geometry were collaboratively optimized at high loads to improve engine performance. A meliorative genetic algorithm coupled with a three-dimensional computational fluid dynamics (CFD) program was adopted as the optimization tool. The optimal GCI combustion strategy is summarized based on the optimization results, and the key parameters affecting engine performance at high loads are further analyzed. The results show that the employment of the open-type piston bowl, high-reactivity fuel, and late start of injection (SOI) is desirable for GCI engines at high loads. Under this strategy, fuel burns in multiple stages, which can reduce the heat release rate and advance the combustion phase. The width of the piston bowl is the geometric parameter with the most notable impact on GCI combustion. Due to the weaker turbulent kinetic energy and the smaller surface area, the larger piston bowl width is conducive to diminishing the heat transfer losses of the engine and promoting the oxidation of unburned hydrocarbon (HC) emissions. Relative to the optimal case, the strategy with the open-type piston bowl, high-reactivity fuel, and early SOI can reduce fuel consumption but results in a higher in-cylinder pressure rise rate and increased ringing intensity (RI). On the contrary, the re-entrant type piston bowl, low-reactivity fuel, and late SOI can significantly reduce the pressure rise rate and RI while deteriorating thermal efficiency.