Principle and structure of a multi-chamber piezoelectric pump with large flow rate integrated into printed circuit board

Parametric simulation of multi-chamber piezoelectric pump proposed by authors shows that its flow rate is positively correlated with chamber compression ratio when height of chamber wall is not less than central deflection of circular piezoelectric unimorph actuator (CPUA). Therefore, in this paper, principle and structure of multi-chamber piezoelectric pump with novel CPUAs with three-layer structure are proposed and realized, so as to improve its chamber compression ratio, and then improve its flow rate. Its processing technology compatible with PCB processing technology is studied and its flow rate model is established. Central deflection of CPUA with three-layer structure and the flow rate characteristics are tested. Experimental results show that when the central deflection of CPUA with three-layer structure reaches the maximum value of 106.8 μm, the chamber compression ratio and flow rate of multi-chamber piezoelectric pump reach the maximum value of 50% and 3.11 mL/min, respectively. The maximum flow rate is increased by 622% compared to unimproved pump. By comparing experimental results with numerical and finite element simulation results, the realized multi-chamber piezoelectric pump has large flow rate and the established flow rate model can predict its flow rate.

Modeling and Dynamic Characteristics of a Novel High-Pressure and Large-Flow Water Hydraulic Proportional Valve

In the field of fully mechanized coal mining equipment, the hydraulic valve used in the hydraulic support is an on/off directional valve. There are many problems caused by the valve such as large pressure shock and discontinuous flow control. Therefore, a novel two-position three-way hydraulic proportional valve suitable for high-pressure and large-flow conditions is proposed to overcome the above problems. The novel valve utilizes a two-stage structure and the displacement follow-up principle is adopted between the pilot stage and the main stage to meet proportional control. In this paper, a simulation model of the novel proportional valve was established after a simplified analysis of the structural principle. Its reliability and the feasibility of the design were verified by the test results under different working conditions. Then, the step response characteristics of the proportional valve under different strokes were predicted and analyzed. Nonlinear characteristics were presented, and the closing time was shorter than the opening time because of the influence of nonlinear flow force. Under different ramp signals, the displacement of the main inlet spool was always approximately equal to the displacement of the pilot stage. Then, the motion relationship between the pilot stage and the main stage was studied, and the influence of the structural parameters on the stability was analyzed.

Experimental Study on Diverter Transport Through Perforations in Multicluster Fracturing of Horizontal Well

Summary Temporary plugging and diverting fracturing of the horizontal well is the primary option to promote production for tight reservoirs. Successful entry of diverters into the perforation is the basis and prerequisite for effective plugging. However, the transport behavior of the diverter during multicluster fracturing remains unclear. In this paper, we build a large-scale diverter transport experimental system, capable of conducting experiments with large flow rates and high pressures. The concerned factors include the injection rate, perforation flow ratio (PFRO), fluid viscosity, and perforation angle. The results show that the diverter transport effect is significantly different because of different flow distribution among perforations. Also, the diverter can enter the perforation only when the flow rate of the perforation reaches a certain value. In addition, the minimum critical PFRO has an “oblique L-shaped” relationship with the injection rate. Although it is difficult for the diverter to enter the perforation on the high side of the horizontal wellbore, increasing the viscosity of the carrying fluid or using a multidensity mixed diverter can effectively solve this problem. Furthermore, the field case shows that the experimentally obtained diverter transport pattern can be applied to the field to predict the location of the diverter and improve the temporary plugging effect. The findings of this work lay a theoretical foundation for subsequent temporary plugging and diverting fracturing control.

Enjeux Liés à la Traversée de la Frontière Bénino-Togolaise dans le Secteur Materi-Mandouri

Les zones frontalières sont des lieux spécifiques où s’effectuent des échanges des biens et des personnes. La présente recherche a pour objectif d’étudier les enjeux liés à la traversée de la frontière bénino-togolaise dans le secteur Materi-Mandouri. Pour atteindre cet objectif, des investigations ont été faites à partir de la collecte des données et informations aux moyens de la recherche documentaire, des observations directes sur le terrain, des entretiens et enquêtes auprès de 93 personnes du milieu de recherche choisies suivant la méthode de choix raisonné. Le traitement des données et l’analyse des résultats se sont focalisés sur l’analyse sociale et l’évaluation des gains auprès des populations cibles. Il ressort des résultats que le commerce (86,66 %), le transport (6,67 %) et la visite des parents (6,66 %) sont les principaux facteurs qui expliquent la présence d’un important flux de personnes dans le secteur de recherche. Aussi, les échanges transfrontaliers entre le Bénin et le Togo contribuent au développement de l’économie locale à travers le chargement, le transport de marchandise et les taxes perçues par les autorités locales. Cependant, les échanges transfrontaliers sont marqués par des contraintes d’ordre social, sécuritaire et infrastructurel. Il faut alors se poser la question de savoir si les actions actuelles permettent de tirer profit du potentiel économique de cette zone frontalière et de faciliter la traversée des populations. Border areas are specific places where people's goods are traded. The objective of this research is to study the issues related to the crossing of the Benin-Togolese border in the Materi-Mandouri sector. To achieve this objective, investigations were carried out from the collection of data and information by means of documentary research, direct observations in the field, interviews and surveys with 93 people from the research community chosen according to the method of reasoned choice. Data processing and outcome analysis focused on social analysis and evaluation of gains among target populations. The results show that trade (86.66%), transport (6.67%) and parental visits (6.66%) are the main factors explaining the presence of a large flow of people in the research sector. Also, cross-border trade between Burkina Faso, Togo and Benin contributes to the development of the local economy through loading, transport of goods and taxes collected by local authorities. However, cross-border trade is marked by social, security and infrastructural constraints. It is then necessary to ask the question of whether the current actions make it possible to take advantage of the economic potential of this border area and to facilitate the crossing of populations.

Analysis of the Influence of Inlet Guide Vanes on the Performance of Shaft Tubular Pumps

To study the influence of inlet guide vanes (IGVs) on the pressure pulsation of a shaft tubular pump, this paper first conducts an experiment to study IGVs. Then, numerical calculations of the shaft tubular pump with and without IGVs are performed to analyze the hydraulic performance and pressure fluctuation characteristics. Finally, the reliability and accuracy of the data are verified by a model test. Numerical simulation results show that with additional IGVs, the pressure pulsation amplitude at the impeller inlet first decreases and then increases under small-flow and design conditions but gradually increases under large-flow conditions. When the IGVs are added to the impeller inlet of the shaft tubular pump, the hydraulic loss in front of the impeller inlet increases, resulting in a significant drop in the head and efficiency of the pump device when the flow rate is less than 1.12 Qd; when the flow rate is greater than 1.12Qd, the head and efficiency of the pump device do not change significantly. IGVs can improve the condition of impeller water inflow and reduce pressure fluctuation on the blade surface.

Pressure Fluctuation Characteristics of High-Speed Centrifugal Pump with Enlarged Flow Design

The pressure fluctuations of high-speed centrifugal pumps are the hotspot in pump research. Pressure fluctuations is differ for different structural designs and flow structures. High-speed centrifugal pumps are usually designed to increase efficiency with an enlarged flow design at a low specific speed, which changes the structure of the pump. In order to analyze the pressure fluctuations of a high-speed centrifugal pump with an enlarged flow design, the pressure was measured, and the flow field of the pump was simulated with different flow rates. Through analysis, we found that pressure fluctuations varied periodically and was consistent with the blade frequency. The pressure fluctuations at the guide vane and the interference region were also closely related to the vortices at the impeller outlet, which changed differently at different flow rates. The results showed that the high-speed centrifugal pump with an enlarged design had better performance at a large flow rate. The results in this paper can provide reference for the design of a pump that should be designed with the enlarged flow method.

A piezoelectric micro gas compressor with parallel-serial hybrid chambers

A piezoelectric micro gas compressor with parallel-serial hybrid chambers (PMGCPS) is presented, which consists of two compression stages of stage I and stage II. The stage I is composed of two piezoelectric driving units connected in parallel, while stage II is composed of a piezoelectric driving unit, forming an integral tower compression structure. Based on the tower compression structure, the PMGCPS owns the dual advantages of large flow rate and high output pressure. The prototype of PMGCPS is designed and manufactured. The driving frequency and voltage characteristics of PMGCPS are experimented. Under the driving frequency of 300 Hz and the driving voltage of 300 Vpp, the maximum flow rate and output pressure of PMGCPS is 795.6 mL/min and 13.4 kPa, respectively. PMGCPS provides new ideas for the further development of piezoelectric micro gas compressor.

Overcoming Downhole Fluid Sampling Challenge Using Dual-Port Straddle Packer in Shallow Viscous Reservoir

Objectives/Scope: Downhole fluid sampling of high quality, low contaminated oil samples with a pumpout wireline formation tester (PWFT) in a shallow unconsolidated reservoir with high H2S, high water salinity and filled with viscous oil is a quite challenging operation. Key properties, related to fluid flow in low pressure reservoirs: formation mechanical weakness, drilling invasion and the high contrast on fluid mobility, have resulted in the failure or impracticality of conventional methods for efficient sampling, resulting in a long sampling time causing high rig cost overhead and often highly contaminated oil samples. Most common problems faced during sampling are: Sand production- causing caving and lost seals and no pressure or samples. Sand plugging of the tool flowline. Operation limitation of pressure drawdown- dictated by extremely low formation pressure and mainly due to having saturated pressure around 20 to 30 psia below formation initial pressure (based on 118 bubble point samples measured in the laboratory). To maintain rock stability and low pressure draw down, fluids were pumped at a low rate, resulting in a long operation time, where a single sample take up to 15 – 20 hours of a pump out. Even with the long pumpout time the collected sample is often highly contaminated based on laboratory PVT analysis report. Methods, Procedures, Process Understanding of the formation properties and its rock mechanics helps to design proper operating techniques to overcome the challenge of viscous oil sampling in unconsolidated sand reservoir. A pre-job geomeechanical study of unconfined sand with very low compressive strength, restricted the flow rate to a maximum drawdown per square inch to maintain rock stability while pumping out. Dual-Port Straddle Packer (figure 1) sampling was introduced to overcome the mentioned challenges. Its large flow area (>1000 in² in 8 ½″ OH section) allowed a high total pumping rate while maintaining very low flow rate per square inch at the sand face, which resulted in an ultra-low draw-down flowing pressure to prevent sand collapse and producing below bubble point pressure that could invalidate further PVT studies. Packer inflation pressure has also been limited to a maximum of 150 to 200 psia above hydrostatic pressure to achieve isolation without overcoming the sand weak compressive strength. During the clean-out operation crude oil tend to separate from water based mud (WBM) filtrate in the packed-off interval due to fluid density difference and immiscibility of the two liquids due to the lower shear rate applied (among others). So a water/oil interface forms within the packed-off interval. As pumping continues, this oil/water fluid contact moves toward the bottom inlet port allowing more clean oil to accumulate at the top. Results, Observations, Conclusions: With the advantage of the dual inlet port straddle packer and the independent opening/closing operating design of each port, a clean segregated oil sample was collected from the top port at an early stage of job operation, saving rig time and cost without compromising collected fluids quality that is valid for PVT studies. Novel/Additive Information: Dual-port Straddle Packer with large flow area (plus filters) with ultra-low drawdown pressure to stay above bubble point pressure in shallow heavy oil reservoirs resulted to be another provided a cost effective technology that can be utilized for collecting downhole samples (DHS) that will undergo PVT studies.

Influence of a rotating nozzle diaphragm on the characteristics of axial low-consumption turbines

Экспериментально исследуются различные компоновки турбинных ступеней с целью обеспечения многорежимности у осевых малорасходных турбин. Определено, что под многорежимностью понимается способность турбины поддерживать величину КПД неизменной, или с небольшими изменениями в достаточно широком диапазоне изменения внешних нагрузок. С новой точки зрения обращено внимание на то, что наиболее выраженными свойствами многорежимности обладают турбины в состав которых входит вращающийся сопловой аппарат. В этой связи рассмотрены авторские результаты экспериментальных исследований биротативных турбин с большим углом поворота потока и двух-ступенчатых осевых турбин с частичным облопачиванием рабочего колеса. Выявлено, у исследованных биротативных турбин свойство многорежимности проявляется при степени парциальности, близкой к единице и регулируется путем изменения соотношения частот вращения соплового аппарата и рабочего колеса. А у одновальных турбин с частичным облопачиванием рабочего колеса свойство многорежимности проявляется в широком диапазоне изменения степени расширения в турбине также при полном подводе рабочего тела. Various arrangements of turbine stages are experimentally investigated in order to ensure multiplicity of operating levels for axial low-consumption turbines. It has been determined that multiplicity is understood as the ability of a turbine to maintain the efficiency value unchanged, or with small changes in a fairly wide range of external loads. From a new point of view, attention is drawn to the fact that the most marked properties of operating levels multiplicity are relevant to the turbines which include a rotating nozzle diaphragm. In this regard, the author's results of experimental studies of birotative turbines with a large flow angle and two-stage axial turbines with partial blading of the running wheel are considered. It was revealed that in the investigated birotative turbines the property of multiplicity is manifested at a degree of partiality close to 1 and is regulated by changing the ratio of the rotation frequencies of the nozzle diaphragm and the running wheel. And in single-shaft turbines with partial blading of the running wheel, the multiplicity property is manifested in a wide range of changes in the degree of expansion in the turbine, also with full supply of the working fluid.