Positive Displacement Pump Research Articles

Структурная оптимизация гидропривода мобильного транспортно-перегрузочного канатного комплекса на основе парето-оптимальных решений

The article proposes a method of structural optimization of the hydraulic drive of mobile transport and reloading rope complexes based on special multi-axle chassis with increased carrying capacity and cross-country ability. At present, this type of technological machines can be considered as a new class of technological overground transport vehicles, which is an effective alternative to stationary freight ropeways for hard-to-reach areas with difficult terrain and, if necessary, the rapid deployment of transport and logistics operations. An algorithm for the formation of the Pareto set is considered, which consists of a variety of alternative versions of the hydraulic drive based on a combination of positive displacement pumps and hydraulic motors of permissible standard sizes. A criterion for choosing the Pareto-optimal solutions of the designed hydraulic drive is proposed, based on three quality indicators — the total mass of the hydraulic machines, the specific power and the efficiency of the hydraulic drive.

Development and Testing of a Wireline-Deployed Positive-Displacement Pump for Late-Life Wells

SummaryWhat do you do after plunger lifting? What if lift gas is not readily available or your liquid level is around a bend? What can you do with a well that has low reservoir pressure, liquid-loading trouble, and fragile economics? Do you give up on the remaining reserves and advance to plugging and abandonment? These questions were considered, and the answers were found to be unsatisfactory. This paper will describe the development and testing of a novel wireline-deployed positive-displacement pump (WLPDP) that was invented to address these challenges.Artificial-lift (AL) pumps have historically been developed with high-producing oil wells in mind. Pumps for late-life wells have mostly been repurposed from these applications and optimized for reduced liquids production. The WLPDP development began with the constraints of late-life wells with the goal of addressing reserves that conventional AL methods would struggle to produce profitably. Internal and industry-wide data were first reviewed to determine what WLPDP specifications would address the majority of late-life wells. The primary target was gas wells, although “stripper” oil wells were also considered. The resulting goal was a pump that could deliver 30 BFPD from 10,000-ft true vertical depth (TVD).The pumping system must be cost-effective to be a viable solution, which led to several design boundaries. Pumps fail and replacement costs can drive economics, so the system must be deployable/retrievable through tubing. The majority of new onshore wells have tortuous geometries, so the system must be able to function at the desired depth despite them—without damaging associated downhole components. The system should use as many off-the-shelf components and known technologies as possible to reduce development costs and encourage integration. Finally, the pump should be able to handle a variety of wellbore liquids, produced gases, and limited solids.The WLPDP was designed to meet the established specifications and boundary conditions. The 2.25-in.-outer-diameter (OD) pump is deployed through tubing. and powered with a standard wireline (WL) logging cable. The cable powers a direct-current (DC) motor that drives an axial piston pump. The piston pump circulates a dielectric oil between two bladders by means of a switching valve. When each bladder expands, it pressurizes inlet-wellbore liquids, pushing them out of the well. Produced gas flows in the annulus between the tubing and production casing. The intake/discharge check valves and bladders are the only internal pump components that contact the wellbore fluids.The WLPDP system was able to meet the design-volume/pressure specifications in all orientations, as confirmed through laboratory and integration testing. Targeted studies were conducted to verify/improve check-valve reliability, gas handling, elastomer suitability, and cable-corrosion resistance. The results of these and related studies will be discussed in the paper.

Managing Water to Minimize Risk in Tailings Storage Facility Design, Construction, and Operation

Reducing the amount of water in a milled tailings storage facility (TSF) is the primary way to reduce the risk of a catastrophic failure. In addition, a significant factor influencing the permitting and development of new mines, or the expansion of existing mines, is the limited availability of water in some mineral-rich countries, which has led to recent advances in water resource management and improved operational practices. Water reduction can be used to thicken the slurry to varying degrees of solids content up to a highly thickened, paste consistency using conventional or positive displacement pumps to transport the tailings, or with filters to mechanically reduce the water and convey the tailings by truck or conveyor. This paper suggests a method to optimize water use and to evaluate and reduce project risks at the conceptual development stage for both a thickened TSF and a filtered TSF.

Multiscale imaging of basal cell dynamics in the functionally mature mammary gland

The mammary epithelium is indispensable for the continued survival of more than 5,000 mammalian species. For some, the volume of milk ejected in a single day exceeds their entire blood volume. Here, we unveil the spatiotemporal properties of physiological signals that orchestrate the ejection of milk from alveolar units and its passage along the mammary ductal network. Using quantitative, multidimensional imaging of mammary cell ensembles from GCaMP6 transgenic mice, we reveal how stimulus evoked Ca2+ oscillations couple to contractions in basal epithelial cells. Moreover, we show that Ca2+-dependent contractions generate the requisite force to physically deform the innermost layer of luminal cells, compelling them to discharge the fluid that they produced and housed. Through the collective action of thousands of these biological positive-displacement pumps, each linked to a contractile ductal network, milk begins its passage toward the dependent neonate, seconds after the command.

Pressure and Flow Rate Fluctuations in Single- and Two-Blade Pumps

Abstract A comparative study on the highly unsteady flow field in single- and two-blade pumps is performed. Stationary pump characteristics, as well as pressure and flow rate fluctuations, are presented. Wall pressure fluctuations were measured in the suction and pressure pipe as well as at several locations within the volute casing by piezoresistive transducers. Flow rate fluctuations were evaluated by a recently presented measurement system based on an electromagnetic flowmeter (Melzer et al. 2020, “A System for Time-Fluctuating Flow Rate Measurements in a Single-Blade Pump Circuit,” Flow Meas. Instrum., 71, p. 101675). Measurements were accompanied by three-dimensional (3D) flow simulations with the open-source cfd software foam-extend. A thorough grid study and validation of the simulation were performed. By a complementary analysis of measurement and simulation results, distinctive differences between both pump types were observed, e.g., flow rate and pressure fluctuation magnitudes are significantly higher in the single-blade pump. In relation to the respective mean values, flow rate fluctuation magnitudes are one order lower than pressure fluctuation magnitudes for both pumps. For the two-blade pump, fluctuations attenuate toward overload irrespective of the particular pump circuit, while they rise for the single-blade pump. 3D simulation results yield detailed insight into the spatially and temporally resolved impeller–volute interaction and reveal that the single-blade impeller pushes a high-pressure flow region forward in a way as a positive displacement pump, resulting in an inherently fluctuating velocity and pressure distribution within the volute.

High-Torque Oscillating Wind Energy Generator

This research investigates a novel concept in small-scale wind-energy generation. Instead of rotating turbine blades, the present concept produces reciprocating motion that is achieved by alternately activating boundary layer control (slot blowing) on opposite sides of a circular cylinder. This is commonly called the Coandă-effect, and here we deploy it periodically on a spring-stabilized vertical cylinder, to produce reciprocating motion. This Co andă-based Re ciprocating (CoRe) system converts wind energy to mechanical work. Compared to wind turbines and windmills, the CoRe system generates higher torque and is therefore well suited to directly driving positive displacement pumps for drip-irrigation or reverse osmosis water desalination. This new approach necessitates the investment of energy in order to extract energy from the wind and therefore a major challenge is to maximize the output/input ratio in order to render the concept viable. Previous preliminary wind tunnel tests conducted on the CoRe system produced gross and net power coefficients of 10% and 3% respectively. However, the blowing slot design has a decisive impact on output power. On the basis of data presented in the literature and our computational analysis, the CoRe system produces significantly greater torque than all types of wind turbines with net power coefficients over 10%.

An experiment of lubricating oil gas concentration in the standardized driving cycles

There always is cavitation in the positive displacement pump, and the bubbles in the lubricating oil have a great influence on the lubricating performance. This paper aims to measure the lubricating oil gas concentration of a passenger car gasoline engine in the standardized driving cycles. We use a passenger car engine lubricating system in the lubricating experiment, simulating the lubricating oil pump working state in the standardized driving cycles. The lubricating oil density and flow rate are measured to calculate the gas concentration in the lubricating oil, according to the engine work state in the standardized driving cycles, including NEDC Urban, NEDC Ultra Urban, WLTC High Speed. The test results show that under the steady-state conditions, the gas volume ratio decreases linearly with the increase of the outlet pressure, the air mass ratio increases with the increase of the pump speed. In the driving cycles, the air mass ratio also increases with the increase of outlet pressure, and it has a high positive correlation with lubricating oil flow and pump speed. With the increase of oil temperature from 25 to 100°C, the air volume ratio decreases by 72.6%, and the air mass ratio decreases by 84.3%. In the engine accelerating state, the rate of lubricating oil flow gain lags behind the pump speed, which makes the lubricating oil gas mass ratio in the accelerating state is significantly higher than that in the decelerating state.

Compact, magnetically actuated, additively manufactured pumps for liquids and gases

We report the proof-of-concept demonstration of novel, valve-less, and magnetically actuated miniature (∼1 cm3) positive displacement pumps for liquids and gases—both single-material-printed pumps with embedded sintered magnets and the first monolithic, fully 3D-printed, multi-material magnetic pumps in the literature; a valve-less design greatly simplifies the pump’s operation and consumes less power compared to designs with active valves, and is less prone to clogging than designs with passive valves. The miniature diaphragm pumps are fabricated using 150 μm-thick to 225 μm-thick layers via fused filament fabrication; the structural parts are printed in pure Nylon 12, while the magnet that makes possible the actuation of the pump chamber is either monolithically printed in Nylon 12 embedded with NdFeB micro-particles or press-fit into the pump after single-material printing of the enclosing piston. The fabrication of the pumps employs a novel multi-material-compatible 3D printing process flow that monolithically creates all features with less than 13 μm of in-plane misalignment. Pump fabrication takes below 75 min to complete and costs under $3.89 in materials. The devices are driven by a rotating magnet and can deliver liquid flow rates as large as 7.88 ml min−1 at 198 Hz for sintered magnet pumps (N35 grade) and 1.68 ml min−1 at 204 Hz for the devices with monolithically 3D-printed magnets (∼N4 grade); the results surpass state-of-the-art, 3D-printed miniature liquid pumps. Actuation of a pump in excess of 14.4 million cycles shows no evidence of degradation, e.g. leaks. A pump with sintered magnet (N48 grade) was characterized as a vacuum pump using air as working fluid, achieving an ultimate pressure of 540 Torr in a 0.61 ml pumping volume and up to 9.3 ml min−1 flow rate at 230 Hz actuation; the results compare well with miniature, commercial, non-3D-printed vacuum pumps.

Endograft exclusion of the false lumen restores local hemodynamics in a model of type B aortic dissection

ObjectiveEndovascular intervention in uncomplicated type B dissection has not been shown conclusively to confer benefit on patients. The hemodynamic effect of primary entry tear coverage is not known. Endovascular stent grafts were deployed in a model of aortic dissection with multiple fenestrations to study these effects. It is hypothesized that endograft deployment will lead to restoration of parabolic true lumen flow as well as elimination of false lumen flow and transluminal jets and vortices locally while maintaining distal false lumen canalization. MethodsThoracic stent grafts were placed in silicone models of aortic dissection with a compliant and mobile intimal flap and installed in a flow loop. Pulsatile fluid flow was established with a custom positive displacement pump, and the models were imaged by four-dimensional flow magnetic resonance imaging. Full flow fields were acquired in the models, and velocities were extracted to calculate flow rates, reverse flow indices, and oscillatory shear index, the last two of which are measures of stagnant and disturbed flows. ResultsComplete obliteration of the false lumen was achieved in grafted aorta, with normal parabolic flow profiles in the true lumen (maximal velocity, 30.4 ± 8.4 cm/s). A blind false lumen pouch was created distal to this with low-velocity (5.8 ± 2.7 cm/s) and highly reversed (27.9% ± 13.9% reverse flow index) flows. In distal free false lumen segments, flows were comparable to ungrafted conditions with maximal velocities on the order of 7.0 ± 2.1 cm/s. Visualization studies revealed forward flow in these regions with left-handed vortices from true to false lumen. Shear calculations in free false lumen regions demonstrated reduced oscillatory shear index. ConclusionsPer the initial hypothesis, endovascular grafting improved true lumen hemodynamics in the grafted region. Just distally, a prothrombotic flow regimen was noted in the false lumen, yet free false lumen distal to this remained canalized. Clinically, this suggests a need for advancing endovascular intervention beyond sole entry tear coverage to prevent further false lumen canalization through uncovered fenestrations.

Design and Analysis of a Variable Buoyancy System for Efficient Hovering Control of Underwater Vehicles with State Feedback Controller

The design process for Variable Buoyancy System (VBS) is not known in full, and existing approaches are not scalable. Furthermore, almost all the small size Autonomous Underwater Vehicles/Gliders (AUVs/G’s) use very low capacity of buoyancy change (in the range of few milliliters) and the large size AUVs require large buoyancy change. Especially for adverse weather conditions, emergency recovery or defense-related applications, higher rate of rising/sinking (heave velocity) is needed along with an ability to hover at certain depth of operation. Depth of UVs can be controlled either by changing the displaced volume or by changing the overall weight and, herein, our focus is on the later. This article presents the problem of design and analysis of VBS for efficient hovering control of underwater vehicles at desired depth using the state feedback controller. We formulate and analyze the design and analysis approach of VBS using the fundamental of mechanics, system dynamics integration and control theory. Buoyancy is controlled by changing the overall weight of the vehicle using the ballasting/de-ballasting of water in ballast tanks through the use of Positive Displacement Pump (PDP) for control in heave velocity and hovering depth. Furthermore, detailed mass metric analysis of scalable design of VBS for different buoyancy capacities is performed to analyze the overall performance of the VBS. Also, the performances of AUVs integrated with VBS of different buoyancy capacities are investigated in both the open loop and closed loop with the LQR state feedback controller. Hovering performance results are presented for three Design Examples (DEs) of AUVs with 2.8 m, 4.0 m and 5.0 m length and they are integrated with various buoyancy capacities at 9 kg/min rate of change of buoyancy. Results indicate that the AUVs achieve the desired depth with almost negligible steady state error and when they reach the desired hovering depth of 400 m the maximum pitch angle achieved of 16.5 degree for all the Des is observed. Maximum heave velocity achieved during sinking is 0.44 m/s and it reduces to zero when the vehicle reaches the desired depth of hovering. The presented computer simulation results indicate good performance and demonstrate that the designed VBS is effective and efficient in changing the buoyancy, controlling and maintaining the depth, controlling the heave velocity and can be used in rescue/attack operations of both the civil and defense UVs.

Design and development of pressurized aqueous fertilizer application system for seeder

In dry land areas, seed germination greatly affected by insufficient soil moisture during sowing. Nitrogenous fertilizers like granular urea remain unavailable due to inadequate soil moisture to dissolve, dilute and convey it to root zone level. Precise application of aqueous fertilizer at root zone depth at the time of sowing enhances seed germination percentage by increasing available soil moisture as per the soil-moisture-crop requirement. A pressurized aqua ferti metering system was designed and developed for application of aqueous fertilizer diluted with water along the side of seed. The prototype consisted of pressurized aqueous fertilizer metering system through positive displacement pump, stationary opening with agitator type seed metering system and shovel type furrow opener with provision of carrying seed and aqueous fertilizer delivery tubes. A pressurized aqueous fertilizer application system consisted of rotary gear pump to vary pump rotational speed and circular distributor for uniform distribution of aqueous fertilizer. The flow rate and pressure were controlled by control valve for required amount of aqueous fertilizer. Three nozzles of size 8, 10 and 12 mm were evaluated at different pump rotational speeds (1800, 1440, 1152, 1080 and 864 rpm) and different control valve positions (0, 2, 4 and 6 kg/cm2 ) for desired flow rate. The discharge rate at a particular pressure was found to vary linearly with the Pump rotational speed and decreased as the line pressure increased. The desired flow rate in pressurized pumping system was obtained in a nozzle of size 10 cm up to a maximum pump speed of 1440 rpm and for a line pressure of less than 4 kg/cm2 .

Computational Fluid Dynamics Modeling of Gaseous Cavitation in Lubricating Vane Pumps: An Approach Based on Dimensional Analysis

Abstract This paper addresses the problem of computational fluid dynamics (CFD) modeling of gaseous cavitation (GC) in lubricating positive-displacement pumps (PDPs). It is important for designers and analysts to predict the dynamic features of air release/dissolution processes which characterize this phenomenon, along with their effects on filling capability and noise-vibration-harshness behavior of the machine. The focus is on the empirical tuning of the commercial homogeneous-flow cavitation model known as dissolved gas model (DGM). Considering an automotive case study of a balanced vane pump (BVP), the effects of air modeling on numerical predictions of discharge flow/pressure ripple and volumetric efficiency have been studied. The tuning time parameters of the model have been correlated to the machine Reynolds number as part of a simplified theoretical background based on dimensional analysis. Considering experimental data at different operating conditions, the tuned model has shown a good capacity in predicting the pressure ripple and the flowrate at the discharge of the pump.

Design, Construction and Evaluation of a Multi-piston Pump

The multi-piston pump, is a linear type of positive displacement pump, working on the principle of direct lift. The height to which the pump can directly lift the water is primarily controlled by factors that include the capacity of the operator, the clearance between the washers and the riser pipe and the speed of the washers. The materials for the construction of this pump can be obtained locally, even from the dump sites, hence its nickname “the pump from the dump”. It would not only serve as a means of lifting water easily, but will also improve the standard of living of the people. This pump could be an option for pumping water in relatively remote and deprived areas. This study highlights on the design, construction and evaluation of multi-piston pump. The pump went through vigorous design procedures and construction stages. The detailed working drawings of the pump were produced and constructions work carried out. Equations were established in order to know how the whole system behaves. It can be deduced from the study that pump discharge is influenced by piston diameter and the distance between the pistons. This pump can be used for small-irrigation schemes.
 Keywords: Pump; Hand-dug wells; Pipes; Discharge; Velocity.

Review of two-line hydraulic drive research

The article provides a brief overview of literary sources from the PRC on the study of a hydraulic drive with two-line control. This hydraulic drive is a new electro-hydraulic system for regulating the flow of a positive displacement pump, developed on the basis of control systems for the electric motor and the volumetric displacement of an adjustable positive displacement pump. The hydraulic drive has two lines of control variables: the rotational speed of the drive motor shaft and the adjustable displacement of the pump. The composite function of the two control lines allows you to create a hydraulic actuator with high efficiency and operating speed. An advanced hydraulic drive with two-line control increases the overall natural frequency of the entire system.

A statistical inference of hydraulic shear and clogging in internally unstable soils

Water-retaining earth structures often experience cyclic hydraulic flow patterns, which are believed to alter the soil fabric. Gap-graded soils are identified to be internally unstable. These soils exhibit a change in their hydraulic conductivity when the critical hydraulic gradient is exceeded. The changes beyond the critical hydraulic gradient, however, are yet to be understood. This research study examines the unsteady nature of clogging and unclogging process in saturated gap-graded soils subjected to hydraulic pulses. A set of 60 min flow (suffusion) tests was conducted using a positive displacement pump to subject a cylindrical specimen to controlled hydraulic flow pulses. The global hydraulic gradient across the specimen was continuously monitored. The grain-size distribution of the soil was re-evaluated after the test. The hydraulic shear stresses induced by the flow pulses were estimated numerically and normalised over the maximum value. Similar trends of the hydraulic conductivity and the applied flow rates do not hold when the duration of the flow pulse is increased. A simple procedure based on statistical inference is proposed to visualise the temporal variation of the clogging and unclogging process subjected to the frequency and the phase shift parameters of the flow pulse.

An Investigation of Tooth Tip Leakages in Gerotor Pumps: Modeling and Experimental Validation

Abstract Gerotors are inexpensive positive displacement pumps commonly used in hydrostatic transmissions, fuel injection, and automotive lubrication systems. In these pumps, leakages at the tooth tips of the gears are the major source of volumetric losses that prevents their usage in high pressure applications. However, due to the curvature of typical gear profiles, the flow relations available in the literature do not accurately model this leakage flow. In this paper, a novel tooth tip leakage flow model is developed based on dimensional analysis. Key geometric and flow parameters are identified and a set of computational fluid dynamics (CFD) simulations are conducted on the tooth tip geometry to establish the flow relationship. This relationship is first verified with the analytical formulation derived from Reynolds equation. Then, an experimental setup is designed to reproduce the flow conditions at the tooth tip of gerotors. Experiments are conducted for a range of geometric and flow parameters, and results from the experiments are used to validate the proposed leakage flow model. The tooth tip leakage flow model developed and validated in this work is valuable for pump designers in determining the impact of gear geometry and clearances on volumetric performance of the pump. Moreover, the model can be readily used in any lumped parameter based simulation tool permitting a fast and accurate prediction of the tooth tip leakage flow and hence the volumetric efficiency of the unit.

CENTRIFUGAL PUMP DESIGN MATERIALS AND SPECIFICATIONS

Pumps are the machines that convert the mechanical energy they receive from the power supply into hydraulic energy. Pumps allow the fluid to reach the pump impeller by bringing the low pressure field to the suction line. The impeller directs the fluid to the outlet pipe and transmits it to the desired point. All pumps are divided into two main groups. These are displacement (positive displacement) and dynamic (non-positive displacement) type. The energy given to the flow in positive displacement pumps is periodically. In dynamic pumps, the energy supplied to increase the velocity of the fluid is continuous. Centrifugal pumps are dynamic pumps and are the most widely used pump type in agricultural irrigation. The heart of the centrifugal pump is the impeller. Centrifugal pumps consist of basic elements such as casing, impeller, diffuser, shaft, seals, stuffing box, suction and discharge ports, bearings, and couplings. Performance and lifetime are important for a successful pump. Performance relates to head, capacity and efficiency. The life span is the total running time of the pump. Pump construction material affects the performance, lifetime, operating regime and cost of the pump. In this study, the selection of materials used in making the centrifugal pump components and the factors affecting the material selection will be examined. As a result; factors such as the type of liquid to be conveyed, the substances contained in the liquid, the pumping temperature, the protection against corrosion, the amount of wear, the place of use of the pump, working pressure, working conditions, frequency of failure, operation and maintenance costs and life expectancy of the pump should be considered.

Research on Flow Characteristics of Straight Line Conjugate Internal Meshing Gear Pump

The improvement of the overall performance of hydraulic pumps is the basis of intelligent hydraulics. Taking the straight line conjugate internal meshing gear pump as the research object, the theoretical flow rate and the geometric flow pulsation rate equations are established in this study through the volume change method. The change laws of the gear pair’s geometric parameters on the theoretical flow rate and the geometric flow pulsation rate are studied. The simulation model of the internal flow channel is established, and the influence factors and the influence degree of the flow pulsation and average flow rate are analyzed. The high-pressure positive displacement pump test system is also designed and built. The performance evaluations are conducted, and the experimental results are analyzed. The results show that the periodic change of the meshing point position is the root cause of the geometric flow pulsation. The theoretical flow rate and the geometric flow pulsation rate are 103.71 L/min and 1.76%, respectively. To increase the theoretical flow rate whilst decreasing the geometric flow pulsation rate, the tip circle radius of the external gear should be increased as much as possible within the allowable range of the design calculation. Amongst the three influencing factors that produce flow pulsation, the oil compressibility has no effect on the flow pulsation. The uneven internal leakage is the main factor, and the geometric flow pulsation only accounts for a small proportion. The internal leakage reduces the simulated flow rate by 3.59 L/min. The difference between the experimental and simulated flow rates is less than 2%. Within the allowable speed range, the rotation speed of the external gear should be increased as much as possible to increase the average flow rate and the volumetric efficiency.

Modeling Gerotor Pump Performance in Artificial Lift for Single-Phase and Multiphase Conditions

Summary Gerotors are positive displacement pumps and candidates for artificial lift in the oil and gas industry. This study evaluates the performance of a unique gerotor pump design under single-phase and multiphase conditions. The gerotor pump performance is modeled with computational fluid dynamics (CFD) to develop a virtual prototype of the multiphase performance behavior. The gas/liquid flow is modeled using a homogeneous multiphase approach. A prototype 3D model of a 400 series gerotor pump suitable for application in a 5½-in. casing is developed. The pump volume displacement is consistent with that to be used in subsequent laboratory experimental tests and field prototype testing. Transient 3D CFD is used to simulate the gerotor pump performance under single-phase and multiphase flow conditions. The complex gerotor motion is modeled in CFD using a dynamic meshing technique. Pump rotor speeds applicable to the range of testing conditions were applied. The gas and liquid phase properties correspond to mineral oil and air at the prototype test conditions. The results of the gerotor pump performance are presented for single-phase and multiphase conditions over a range of gas volume fractions (GVFs) from 0 to 0.75. The CFD results show that the flow rate decreases approximately linearly with pump differential pressure, which is typical of positive displacement pumps. Pump performance and efficiency curves are developed relating the pump differential pressure and flow rate. The CFD model methodology is presented with consideration to appropriate selection of the numerical methods, multiphase model, mesh design, dynamic mesh motion, and other aspects to improve the reliability of the numerical simulations. For the same differential pressure, increasing the GVF decreases the gerotor total pumping volume rates. The results establish a first baseline for the pumping system for subsequent comparison with physical model testing to ascertain gas/liquid handling capability of the pump for further optimization for field application. This study evaluates and highlights the potential applicability of gerotors as an alternative artificial lift technology for multiphase pumping. This technology with further development in addition to its inherent mechanical simplicity and compactness can serve as a promising candidate for surface and downhole multiphase pressure boosting for production in the oil and gas industry.

Influence of water/cement ratio, and type and concentration of chemical additives on the static and dynamic yield stresses of Portland cement paste

The influence of water/cement w/c ratio, and type and concentration of two chemical additives, lignosulfonate and polycarboxylate, on the static SYS and dynamic DYS yield stresses of Portland cement paste was studied. Large differences between both magnitudes express the existence of, at least, two different microstructural levels. This information is relevant for the design in concrete applications. Specifically, it was found that larger differences between the microstructures that characterize both yield stress values were obtained when w/c ratio decreased and the amount of the plasticizers increased. With the empirical functions that were proposed for these dependencies, the calculation of the hydraulic power of a positive displacement pump was made. Results indicate that higher pumping power is required for cement pastes with lower w/c ratios and low polycarboxylic additive content, and when lower w/c ratio is combined with high amount of lignosulfonate additive.