Piston Pressure Research Articles

The Use of Acoustic Emission Elastic Waves for Diagnosing High Pressure Mud Pumps Used on Drilling Rigs

Although mud pumps are vital components of a drilling rig, their failures are frequent. The identification of technical condition of these high-pressure piston pumps is difficult. There are no reliable criteria for the assessment of mud pump condition. In this paper, faults of the pump valve module are identified by means of acoustic emission (AE) signals. The characteristics of these signals are extracted by wavelet packet signal processing. This method has been verified by experiments conducted on a NOV (National Oilwell Varco) -made triplex 14-P-220 mud pump (mounted in the drillship). The results show that the wavelet packet signal processing method can effectively extract the frequency band energy eigenvalues of the signals. Besides, some operational problems associated with high pressure piston mud pumps are presented. A non-invasive method for diagnosing the technical condition of such pumps is being developed at the Maritime University of Szczecin.

Experimental assessment of damping and heat transfer coefficients in an active free piston Stirling engine using genetic algorithm

In this work, two critical parameters of an active free piston Stirling engine (AFPSE) namely, the heat transfer and damping coefficients are practically estimated using genetic algorithm (GA). Although, the mentioned parameters play a significant role in the accuracy of data obtained from the mathematical models, they cannot be measured directly. Indeed, there are no specific sensors to measure damping and heat transfer coefficients and it is the main challenge to achieve their practical values. Consequently, this work attempts to present an innovative scheme to estimate such immeasurable parameters based on other measurable variables. First, the modeling approach of the AFPSE is described and the significance of the mentioned parameters is highlighted. Then, two experimental works are conducted to measure gas pressure and power piston displacement at each engine frequency for identifying the immeasurable parameters indirectly. Subsequently, an appropriate objective function based on the error between the experimental and simulation data is defined for each of the identification scheme. Next, the GA is used to achieve the mentioned unknown parameters so as to minimize the proposed objective functions. Finally, the experimental and simulated outcomes clearly affirm the effectiveness of the proposed identification scheme of the considered immeasurable parameters.

Study on Oil Film Characteristics of Piston-Cylinder Pair of Ultra-High Pressure Axial Piston Pump

The piston-cylinder pair is the key friction pairs in the piston pump. Its performance determines the volume efficiency of piston pump. With the increase of load pressure, the leakage at the clearance of piston-cylinder pair will also increase. In order to reduce leakage, the clearance of the piston-cylinder pair of the ultra-high pressure piston pump is smaller than that of the medium-high pressure piston pump. In order to explore whether the piston will stuck in the narrow gap, it is necessary to study the oil film characteristics of the piston-cylinder pair under the condition of ultra-high pressure, so as to provide a theoretical basis for the optimal design of the piston-cylinder pair of ultra-high pressure axial piston pump. In this paper, an ultra-high pressure axial piston pump is taken as the research object, and its structural characteristics are analyzed. The mathematical model of the oil film thickness of the piston-cylinder pair is established by using the cosine theorem in the cross section of the piston. The finite volume method is used to discretize the Reynolds equation of the oil film of the piston-cylinder pair, and the over relaxation iteration method is used to solve the discrete equations, and the mathematical model of the oil film pressure of the piston-cylinder pair is obtained. The mathematical model of oil film thickness and pressure field of piston-cylinder pair is solved by programming. The dynamic change process of oil film thickness and pressure field of the plunger pair of the ultra-high pressure axial piston pump under the load of 20 MPa and 70 MPa is obtained. Under the two conditions, the thinnest area of the oil film reaches 3 μm and 2 μm dangerous area respectively; the oil film pressure reaches 20 MPa and 70 MPa respectively when the swashplate rotates 10° and continues to increase with the increase of swashplate rotation angle. When the rotation angle reaches 90°, the oil film pressure also reaches the maximum value, but there is no pressure spike phenomenon. The oil film pressure characteristics of ultra-high pressure axial piston pump under conventional and ultra-high pressure conditions were obtained by modification and experimentation.

Influence of pressure distribution in the gap of piston-cylinder unit and properties of working fluid PES-3 on characteristics of high pressure piston-cylinder unit

A simulation of the use of PES-3 liquid in a high-pressure piston-cylinder units was performed, and the parameters of the piston-cylinder units were determined in the article. The equations of the mathematical model describing the pressure change in the gap between the piston and the cylinder are given. As a result of the calculations, the pressure distributions in the gap between the piston and the cylinder are determined at under piston pressures less than 1.6 GPa. The profiles of the gaps between the deformed piston and cylinder at different under piston pressures are calculated. The dependences of the speed of lowering the piston and the effective gap on the under piston pressure at different gaps of the undeformed piston-cylinder unit are obtained. The research results can be used in the design of piston cylinder units operating on PES-3 liquid in the pressure range of 0.01–1.6 GPa.

Design of Piston Gauge Verification Data Processing System Based on LabVIEW

In order to check the weight of the quality of piston and its connecting parts more conveniently, this paper designs a set of data processing system for piston gauge measurement and verification based on LabVIEW. The system uses LabVIEW development platform to establish a visual human-machine interface. According to the requirements of JJG59-2007 National Verification Regulation of Piston Pressure Gauge, a set of data processing system is designed and completed. The system can accurately and effectively calculate the special weights of Special Weight, Piston and Connecting Parts of Piston Gauge according to the verification data. It greatly improves the work efficiency. The research lays a foundation for adding piston position indication device and automatic generating and exporting of original records in the system.

High Pressure Homogenizer in Pharmaceuticals: Understanding Its Critical Processing Parameters and Applications

The high pressure homogenizer (HPH) in pharmaceutical industry is specifically used for size reduction, mixing, and stabilization of dispersions or droplets. In HPH, liquid is passed through a narrow gap under high pressure where the different processing parameters lead to changes in globule/particle size. Understanding these processing parameters with a view to its pharmaceutical applications will be useful in producing a consistent and predefined quality of pharmaceuticals. A systematic literature review using the available knowledge space was conducted by publications available on the subject matter until 2018. The keywords used in different combinations like “high pressure homogenization,” “pharmaceuticals,” and “process parameters of HPH” were searched in databases of web of science, PubMed, and Scopus. The collected data was systematically analyzed. The review findings revealed the importance of understanding the basics engineering involved in construction of the HPH instrument, which included the types of pressure pumps and piston pumps, geometry and design of valves, O rings, and impact rings in HPH. Getting into the vertical knowledge obtained, the mechanism of droplet fragmentation and other critical processing parameters were shown to be affecting the product output from HPH. The review gives an insight to the understanding of processing parameters and colloidal principles involved in achieving the different pharmaceutical applications by the formulations formulated using the HPH.

Experimental and computational investigation of fluid structure interaction of flexible tube’s dynamic properties

Flexible tubes are often used in hydraulic measurement, be it connection between pieces of hydraulic equipment or an extension from point of measurement to measuring sensor or as a substitute for a different material e.g. biological tissue. Such tube material allows for rather large deformation and therefore influences measured parameters. Laboratory set up consisting of pressure sensors and piston pulsator was used to gather experimental data. Frequency response and properties were obtained in a range of frequencies. Fluid structure interaction simulation using ANSYS FEM and Fluent CFD packages and simulation in ANSYS Mechanical with acoustic-capabilities were used to compare experimental and computational data. Results show correlation between different approaches. Suitability of flexible tubes is discussed regarding the obtained properties.

Study on the Dynamic Characteristics of a Hydraulic Continuous Variable Compression Ratio System

Variable compression ratio (VCR) technology has long been recognized as a method for improving the engine performance, efficiency, and fuel economy of automobiles, with reduced emissions. In this paper, a novel hydraulic continuous VCR system based on the principle of an adjustable hydraulic volume is introduced. The continuous variable compression ratio of the VCR system is realized by the hydraulic system controlling the rotation of the eccentric pin to change the positions of the top dead center (TDC) and the bottom dead center (BDC). The construction of the mathematical model and simulation model of the VCR system is also presented in this paper. The piston motion characteristics, flow characteristics, and pressure characteristics of the hydraulic system of the VCR system at different engine speeds and adjustment quantities are studied by simulation in this paper. The simulation results show that the VCR system has a fast response and good dynamic characteristics, and can achieve continuous adjustment of the compression ratio.

Effective Use of DP-PSA Gas Separation Technology

Based on the analysis of Dual Piston Pressure Swing Adsorption (DP-PSA) technology, in which only one adsorber is used, the possibility of a significant reduction in energy costs for gas mixture separation is been demonstrated. A mathematical model of a DP-PSA system for the separation of gas mixtures is described. Using this mathematical model, optimization of parameters of the DP-PSA system was carried out to produce oxygen from air. The concentration of production oxygen was chosen as the objective function. The optimized parameters were the phase shift angle of piston movement and the ratio of volumes displaced by the pistons. The optimum phase of piston movement in the cylinder filled with air is 51° ahead of the phase of piston movement in the cylinder filled with production oxygen. In this case, the concentration of oxygen at the outlet from the unit reaches 94.7 %. The optimal ratio of volumes displaced by the pistons turned out to be 1.0. The wave approach was used to analyze and calculate the periodic adsorption processes, as well as simulate DP-PSA systems.

Scrutinizing the sources of inefficiencies in the piston-cylinder clearance of an oil-free linear compressor

The piston of linear compressors is subjected to low side loads and metal contact can be avoided by feeding high-pressure refrigerant gas from the discharge system into the piston-cylinder clearance. This paper reports a thorough study on the inefficiencies associated with leakage and viscous friction brought about by the transient compressible fluid flow in the piston-cylinder clearance of an oil-free linear compressor. The main objective is to understand the effect of design parameters, such as compressor speed, piston oscillation amplitude, pressure ratio and radial clearance, on the volumetric and isentropic efficiencies. The compressor efficiency was found to be mainly affected by the clearance and pressure ratio. A reduction of 2.5% in the volumetric efficiency and 4.2% in the isentropic efficiency, for instance, were predicted when the radial clearance was varied from 2.5 to 10.0 µm.

A novel fluid structure interaction model for the grooved piston-cylinder interface in axial piston pump

In the design of high pressure and high speed axial piston pump, grooves on piston are often used to improve the lubrication condition of piston-cylinder interface. However, the position and parameters of grooves are still depending on experience and experiment. A novel fluid structure interaction (FSI) model for the grooved piston-cylinder interface is formulated in this study, which aims to reveal the performance of oil film. Based on the kinematic analysis of piston, the instantaneous pressure of displacement chamber in piston pump is calculated. Reynolds equation is discretized and solved on the oil film mesh to obtain the pressure distribution of oil film. Eccentricities of piston center is iterated out with force balance loop. Influence method is used to calculate the deformation of both piston and cylinder. Six types of piston are introduced and compared in this study. Simulation results indicate that the grooves near displacement chamber can improve the trajectory of the micro motion of piston, which finally avoid contact between piston and cylinder and reduce viscous friction power loss. The grooves far from displacement chamber could store oil and reduce the leakage flow piston-cylinder interface.

Theoretical and experimental studies of a gas stamping device with a piston pressure multiplier

In many industries, the share of small-scale production plants is significant. In these conditions, compared with traditional methods of pressure treatment, pulse pressure treatment methods, one of the varieties of which is gas stamping, are more efficient. However, the known devices of gas stamping provide mainly stamping of thin-walled parts. To expand the technological capabilities of gas stamping, the authors developed a gas stamping device with a piston pressure multiplier, in which heating and deformation of the stamping workpiece is carried out using the energy of combustion of fuel mixtures in the combustion chamber, in the working cylinder and in the cavity of the matrix. This article is devoted to the study of the workflow of this device. Theoretical analysis of the workflow was carried out, and, as a result, a pattern was determined for the variation of the pressure that performs the stamping process in the working cylinder. In particular, it was found that at the final stage of the stamping process, due to the energy of combustion of the fuel mixture, the pressure in the working cylinder increases 1.5...2 times, which allows a significant increase in the thickness of the parts to be stamped. An experimental gas stamping device with a piston pressure multiplier was developed, and experimental studies were carried out. The studies confirmed the main results of the theoretical analysis: the discrepancy between the theoretical and experimental values of the degree of pressure multiplication in the working cylinder does not exceed 11%.

Separation of water–alcohol mixtures using carbon nanotubes under an electric field

Carbon nanotubes (CNTs) are a promising candidate for separation membranes because of their ability to transport substances at very high flow rates. However, there is a tradeoff between achieving a high selectivity using small pore sizes and the reduction of water flux. Here, using molecular dynamics simulations, we report that CNTs can effectively separate water-methanol mixtures under an electric field. Without an electric field and under piston pressure, both water and methanol flow through a CNT, resulting in no separation effect. In contrast, under an electric field and high piston pressure, CNTs allow selective water permeation while rejecting the permeation of methanol molecules. This separation effect is caused by the ordered structures of water molecules in the CNT. A high filtering effect is observed under the conditions of high methanol concentration in the solution or even with large-diameter CNTs up to 3.39 nm. As long as the ordered structure of water in the CNTs can be maintained, the strong filtering effect can be maintained.

Research on the Influence of Piston Constraint on the Temperature Field of Multi-disc Clutch

The two-dimensional finite element model of multi-disc clutch friction pair was established by Abaqus simulation software, and the contact pressure of the friction surface under different piston constraints was calculated and analyzed. Considering contact pressure as the main heat-generating factor, the two-dimensional heat conduction process was numerically discretized by the implicit difference method. Then the temperature model of the multi-disc clutch friction pair was programmed in Matlab. The bench test verified the correctness of the temperature model. It is found that the temperature field between components is different and shows uneven distribution under the actual constraint. The local temperature of the component near the concentrated load is the highest, in which the radial temperature difference is the largest. The arrangement in which the piston pressure is concentrated in middle diameter produces the lowest temperature and the smallest radial temperature difference, which can effectively avoid thermal deformation of the component due to uneven temperature distribution.

Investigation of the effect of nozzle design on rheological bioprinting properties using computational fluid dynamics

Bioprinting is the utilization of techniques derived from three-dimensional printing to generate complex biological structures which may replace natural tissues or organs. It employs high spatial resolution deposition of different cell types, growth factors and biomaterials. Those together form bioinks, which are the bioprinting inputs, analogously to conventional inks with regard to inkjet printing. In extrusion bioprinting, continuous bioink filaments are deposited layer by layer on a surface by means of an extruder nozzle, employing the displacement of a piston or pneumatic pressure. If mechanical stresses applied on a cell membrane exceed a critical value, which depends on the cell type, the cell membrane may disrupt. Computational fluid dynamics (CFD) simulations of the bioink extrusion were done to evaluate shear stresses caused by the internal pressure of extruder nozzles during bioprinting. Different three-dimensional conical nozzle designs were tested by varying angles of convergence, lengths, input diameters and output diameters of the nozzles. The powerlaw model, with constants k = 109.73 Pa·s0,154 and n = 0.154, was used to describe the expected non- Newtonian behavior of the bioink. Shear stresses and shear rates were evaluated for each nozzle design considering different pressures or velocities as boundary conditions at the nozzle entrance. The maximum wall shear stress value on each different nozzle varied between 1,038 Pa and 4,915 Pa. The results indicated which details of nozzle geometry are most relevant in order to optimize bioprinting. The best conditions for bioink rheology were also evaluated to ensure good printability and high cell viability. Keywords: bioink, bioprinting, biofabrication, 3D printing, CFD.

Development of an innovative lightweight piston through process combination “casting – forging”

Abstract The development of an innovative hybrid piston for marine engines is intended to help reducing emissions and operating costs. The piston consists of a piston base and a top part. In the manufacture of the piston base, a preform is cast and the final geometry is produced by means of subsequent forming (forging). This significantly improves the mechanical properties of the As a result of the possible material advantages in the overall process chain, the piston base can be designed as a lightweight component. By examining the entire primary – process chain, the use of materials is significantly reduced, especially in the casting production route, since even minor internal defects can be tolerated after the preform has been cast. For the subsequent forging process, this material pre-distribution thus represents an optimum initial forging shape. The upper part of the piston is made of a thick-film composite. Here, a nickel-alloy is applied to the piston blank by laser welding or PTA build-up welding prior to the forging process. The nickel-alloy is formed together with the base material, which in turn has a positive effect on the capacity to withstand stresses. An additional heat treatment improves the high temperature resistance. Due to the higher strength and corrosion resistance of the piston head, temperature and pressure in the combustion chamber can be increased, enabling the required reduction of emissions and fuel.

Influence of the face surface shape of the piston on the limit value of compaction stress in the process of dry ice agglomeration

This paper presents the results of research on improving the efficiency of the mechanical agglomeration through describing the influence of the shape of the piston pressure face on the limit force value. The focus of this study is the geometrical parameters which are describing the shape of the piston pressure face. Where these parameters influence on the value of the limit stress in the process of mechanical agglomeration of crystallized carbon dioxide. The first part of the paper proposes a model describing the influence of the geometric parameters of the piston pressure face on the value of axial force during the subsequent compression phase of the process. The research part of the paper presents the empirical research results to verify the proposed model. The results of the work will be used to determine the influence of the described geometrical parameters of the dry ice residue on the axial force value. The derived mathematical model will be used for defining the design requirements as the starting point for the design and building of dry ice compression and granulation machines.

Marchetti Flat Dilatometer Tests in a Virtual Calibration Chamber

Abstract Calibration chambers are frequently used to verify, adapt, or both verify and adapt empirical relations between different state variables and in situ test results. Virtual calibration chambers (VCC) built with 3D discrete element models may be used to extend and partially substitute costly physical testing series. VCC are used here to explore the mechanics of flat dilatometer penetration and expansion. Results obtained for a simulation of physical tests in Ticino sand are presented. Blade tip resistance during penetration is in good agreement with the experiments. A piston-like design is used for the blade so that larger displacements may be applied than it is possible with a membrane. Initial piston pressures in the expansion curves are very low, strongly affected by the scaled-up grain sizes. Despite that difficulty, expansion curves may be easily interpreted to recover dilatometer moduli ED close to those observed in the physical experiments. Particle-scale examination of the results allows a firmer understanding of the current limitations and future potential of the technique.

Development and research of a device for gas sheet stamping with a piston pressure multiplier

Traditionally, sheet stamping is carried out in the cold state of the workpiece being processed. At the same time, due to the limited plasticity of the workpiece, stamping parts of complex shape is performed in several operating steps, which significantly increases the cost of production. The article is devoted to the development and research of a device providing stamping of parts with heating of the workpiece being processed. The device comprises a die and a working cylinder between which the workpiece is placed, as well as a combustion chamber separated from the working cylinder by a piston. The heating of the sheet billet and its punching is carried out in two stages within 1...2 s with its exposure to the action of gas mixture combustion products. At the first stage, the billet is heated and deformed by the combustion products formed in the die cavity and the working cylinder, whereas at the second stage these processes take place due to the energy of the combustion products formed in the combustion chamber. The workflow of the developed device was studied. The regularities of the pressure and temperature changes of the gas that heats and deforms the billet being stamped were established. The optimum proportions of the volumes of the combustion chamber and the working cylinder were determined. The developed device ensures stamping of complex-shaped parts in one process step due to the heating of the workpiece. In this device the pressure on the surface of the workpiece being processed is 2...3 times higher compared with the existing analogues, which ensures stamping of heavy-thickness parts, as well as parts made of hard-to-deform alloys.

Optimization of piston type extrusion (PTE) techniques for 3D printed food

The piston type extrusion (PTE) method with the employ of the Internet of Things (IoT) technology for ejecting bio-materials and high viscosity material by using an extruder have been successfully optimized in terms of the head traveling speed and the piston pressure with food materials of various viscosities. Along with mathematical approach by using Hagen Poisoulle (HP) equation governing high viscosity flow, the study demonstrated that the material's qv (volumetric flow rate) has constant output at 3.6 × 10−8 m3/s with the material viscosity of 0.001–1000 Pa.S. and the PTE method has shown to be effective when the water content is higher than 33 wt %. When the high viscosity material is stacked more than 20 layers at an optimized height, the three-dimensional shape can be maintained between the head traveling speed of 1.5 × 10−2 and 2.0 × 10−2 m/s.