Gear Pump Research Articles

Degradation of Hydraulic System due to Wear Particles or Medium Test Dust

Contamination in hydraulic systems is the cause of 70% of failures. This study highlights the performance degradation caused by solid particle contamination of hydraulic components: hydraulic gear pump, 4/3 valve, and orbital motor. Experimental durability tests of components with wear particles and test dust are used to investigate the effects of accelerated wear caused by these two types of contaminants. Results show that oil contaminated with wear particles reduces the volumetric efficiency of the gear pump by 18% and the hydraulic valve by only 0.8%, while oil contaminated with test dust reduces the efficiency of the pump by 76% and the hydraulic valve by 0.9%. This research provides insights for accelerating hydraulic component testing to improve system reliability and longevity.

Helical Gear Pump: A Comparison between a Lumped Parameter and a Computational Fluid Dynamics-Based Approaches

This research presents a comparison between two numerical approaches developed and later compared for studying External Gear Pumps (EGPs). Models have been developed for studying pumps with helical gears. Firstly, a three-dimensional (3D) CFD numerical model has been built using a commercial code. Then, a new tool called EgeMATor MP+, completely developed by the authors and capable of completely simulating this pump’s typologies is presented. Thanks to different subroutines developed in different interconnected environments, this tool can fully analyze those pumps, starting from the drawing. Both numerical approaches have been detailed, highlighting their strengths and weaknesses and the tweaking required to reach more accurate results. Both numerical models have been set up with the same boundary conditions to obtain a more accurate comparison. Comparisons have been performed using tests performed on a commercial pump taken as reference, focusing on steady-state volumetric performance as well as the transient features of the outlet port pressure oscillations. The comparison of the (Q,p) characteristics showed that the 3D CFD numerical model has a slightly better accuracy, but both models have errors that fall into the uncertainty range of the experimental measurements. In addition, the pressure ripples comparison verified good agreements, where also the double flank behavior of the pump is predicted. While comparing the two simulation approaches, the paper highlights the limits and strengths of each one of the two approaches. In particular, it is shown how both models can match the experimental results considering proper assumptions. The paper constitutes a unique contribution to the field of numerical simulation of EGPs and represents a useful reference to designers looking for suitable methods for simulating existing or novel design solutions.

IMPACT OF SUCTION SPACE LEAKS ON THE DISCHARGE PRESSURE PULSATION OF POSITIVE DISPLACEMENT PUMP

This paper presents the results of the experiments related to measuring the impact of the suction space leaks in the gear pump on the pressure pulsation, resulting in the aeration of hydraulic fluid. The research authors claim that it is possible to detect leaks in the suction line, causing aeration of the hydraulic fluid, by recording and analyzing the pressure pulsation in the positive displacement pump discharge line. The measurements were performed for six leakage values, five discharge pressure settings and under constant hydraulic fluid temperature. The obtained results were analyzed in the time and frequency domains. The results of experimental research confirmed the author’s thesis.

NUMERICAL SIMULATION OF A GEAR

To navigate safely, the ship must be manoeuvrable and have good stability. The steering of the ship depends on a number of factors such as: the means of steering used, the geometric shapes of the hull (stern area), the ratios between the main dimensions (LCWL/B and B/T), the number, position and direction of rotation of the engine. and the hydro-meteorological conditions in which they sail (water, air, wind, waves). Every ship, with the exception of barges, must have a robust and safe steering system to ensure manoeuvrability and sea stability. These installations can be: rudder with hydrodynamic profile, installation with adjustable nozzles and other installations approved by the Classification Societies. In this particular study an analysis on a gear pump fitted in the azimuth system of a chemical tanker is being made, using a CFD technology. The main aim is to study the efficiency of this pump by comparing the CFD analysis results with the results in real operational condition. Main parameters focused on are outlet flow, suction column, power and pump efficiency. There are several differences registered in the case of suction column and power, but they are not that high, while parameters outlet flow and pump efficiency are almost identical.

Numerical Investigation on Pairing Solutions of Non-Positive Displacement Pumps and Internal Gear Pump for High-Speed Design

Raising the working speed of hydraulic pumps to maximize the efficient matching range of electric motors is one of the possible ways to achieve energy efficiency in electric machinery. By means of a simulation method verified with subsequent experiments in terms of filling efficiency, this paper first analyzed the suction capacity of crescent-type internal gear pumps with different geometric parameters at high speed, and the gear pair that is more suitable for high-speed operation was obtained. Subsequently, as the more significant contributions, two pairing solutions of a non-positive displacement pump and an internal gear pump were proposed to pressurize the inlet of the gear pump to keep it from cavitating. In the compact design solution, the inclined-holes type and axial-flow blade pumps share the same speed as the hydraulic pump, while the decentralized layout solution allows for flexible adjustment of the centrifugal impeller-type pump speed to maximize the filling capability. The final simulation results show that, with the help of inclined-holes type and centrifugal impeller type pumps, the filling efficiency of the internal gear pump at 6000 rpm can be improved by 3.59% and 5.84%, respectively, while the axial-flow blades pump fails to eliminate cavitation regardless of speed. Moreover, when the hydraulic pump works at 6000 rpm, the centrifugal impeller speed needs to be set above 2500 rpm to make sense.

Evaluation of the Operational Reliability of Gear Hydraulic Pumps Repaired Using the Electric Spark Processing Method

Evaluation of the Operational Reliability of Gear Hydraulic Pumps Repaired Using the Electric Spark Processing Method

Analysis of the Gear Pump’s Acoustic Properties Taking into Account the Classification of Induction Trees

This paper presents an analysis of selected acoustic properties of gear pumps. For this purpose, the characteristics of selected types of displacement pumps—gear pumps—are discussed, as well as discrete methods of identification and classification of acoustic signals. The basic assumptions of noise analysis in reverberation chambers are discussed, and an analysis of the distribution of measurement points using decision trees and statistical analysis of measured noise levels was conducted. The object for the conducted research was a gear pump with a undercut tooth profile developed by Wytwórnia Pomp Zębatych Sp. z o.o. in Wrocław. Our own research indicates that the acoustic performance of gear units depends on a number of factors, including, in particular, the technology and quality of manufacture and the geometric parameters of the toothing. The aim of the analyses presented in this paper was to determine which of the microphones has the most important impact on the level of determined measured noise generated in the acoustic chamber. The paper presents an analysis aimed at ranking the importance of eight measurement points in which the microphones are located. To this end, induction trees were developed, and a statistical analysis of the measurement results obtained for selected frequency and sound pressure ranges was prepared. The analysis made it possible to optimize the arrangement of microphones in the chamber without unnecessary analysis of each of the microphones separately.

Effect of Crude Oil and Nitrogen Gas Flow Rates on the Time Taken for Flow Initiation of Waxy Crude Oil

Transportation of waxy crude oil in a production pipeline often encountered flow assurance issues, such as wax deposition. In a case where pipeline shutdown is needed, wax deposit is likely to form within the pipelines, which leads to operational complexity during the restart phase. Commonly, crude oil restarts to flow after a significantly high restart pressure is pumped longer than is necessary. This is due to the physical hindrance caused by the solid wax, which requires additional pressure to disintegrate it before achieving a steady crude oil flow. This study aims to investigate the effect of crude oil and nitrogen gas flow rates on the time taken for crude oil flow initiation using a flow loop rig, which is connected to a nitrogen gas injection system. The nitrogen gas was injected into the test section pipeline at predetermined flow rates within specified periods. After 45 min of static cooling, the crude oil gear pump is switched on to build sufficient pressure to initiate the waxy crude oil flow in the pipeline. Additionally, a statistical analysis by the response surface methodology was also performed by Minitab® 19 software. Results show that the maximum reduction in flow initiation is 73.7% at 5 L/min of crude oil and 1 L/min of nitrogen gas. This study reveals that the presence of nitrogen gas improved the pipeline restart phase by minimizing both restart pressure and time taken for flow initiation.

Підвищення ефективності робочого циклу паливного шестерного насоса високого тиску за рахунок використання струминного насоса в якості ступеня підкачування

This article analyzes the possibility of increasing the efficiency of the gear pump operating cycle by using a jet pump as a booster stage. The design of gear pumps is performed for one mode, and most often, it is a mode with minimum speed and high consumption relative to rotation speed. For gas turbine engines, this is the take-off mode, in which the aircraft operates for a few minutes of the entire flight cycle. In other modes, the pump capacity is excessive, reaching more than twice the value in some operational conditions. Due to the excess capacity, overflow valves are used to synchronize the operation of the engine and pump. This approach is a classic solution, but it creates additional mechanical losses and, as a result, reduces the efficiency of the operating cycle of the pump. Therefore, there is a need to improve the matching of engine requirements and pump performance. In this article, a solution that can improve the operating cycle of pumping units within the framework of a classical drive box assembly was analyzed. In the introductory section, the generalized flight cycle of a transport aircraft is analyzed. Based on the results, the modes were determined for which the design calculations of the jet pump were performed. First, the relative characteristics of pressure increase and efficiency are considered. The geometric and operational boundary conditions are accepted considering the fuel overflow relative to the generalized flight cycle. The obtained characteristics are used as a basis for selecting the geometric ratio for the modes with the highest pressure and efficiency. Based on these results, the geometric dimensions of the main sections and the value of the pressure increase at the outlet of the jet pump were obtained. Based on the characteristics of the pressure increase behind the jet pump, the relative characteristics of the reduction in power consumption in the gear pump shaft were obtained. Considering the level of overflow and operating time, the use of a jet pump will save about 50% of the energy input. This is a direct improvement in the operating cycle, and the increased pump inlet pressure will also reduce bearing wear, increase cavitation resistance, and reduce wear from cavitation erosion.

Functional dyeable polypropylene fabric development and process parameter optimization. Part II: Development of graphene thermal insulation dyeable polypropylene fabric with process parameter optimization

This series of studies developed a nanographene modified dyeable polypropylene yarn with far-infrared properties making it suitable for winter clothing fabrics. In this paper, part II, the dyeable polypropylene granules developed in part I are used as a base material and, with the addition of graphene nanopowder, melt-mixed and melt-spun to produce 75 d/24 f fully drawn yarn. The physical properties of the yarn, namely, yarn count, tensile strength, elongation at break, far-infrared emissivity, and far-infrared temperature rise, are investigated, and the impact of the melt-spinning process parameters, namely, graphene nanopowder content, mold temperature, melt temperature, gear pump speed, hot roller speed and take-up speed on the quality of the yarn, is determined. The Taguchi method, combined with gray relational analysis, is used to design experiments through which an optimal set of melt-spinning process parameters maximizing the multi-characteristic quality of the yarn is obtained. This optimized nanographene modified dyeable polypropylene yarn has a tensile strength of 3.5 g/d, elongation at break of 41.0%, yarn count of 75.3 d, far-infrared emissivity of 82%, far-infrared temperature rise of 21.0°C, washing fastness grade of 3–4 and surface resistance of 3 × 108 Ω.

Recent Advances of Flow Rate Simulation in Gear Pumps

The gear pump is a rotating pump that moves and changes depending on the working volume that is created between the gear and the pump cylinder to transport or pressurize the liquid. It is one of the most widely used hydraulic pumping devices. It has been adopted in road equipment, conveyor systems, and other industrial machineries. Its performance is critical to the engineering equipment. With the development of fluid mechanics, the computational fluid dynamic (CFD) technique is widely used to predict the internal flow filed of gear pumps. CFD can provide researchers more intuitive observation and analysis to help the designers to enhance the effectiveness of gear pump. This paper summarizes the principle of flow simulation methods for gear pump and its applications. The research results and key findings are summarized. Defects of existing research are pointed out and suggestions for future research are provided. To sum up, this paper has a certain reference value for researchers who would like to know the hydraulic simulation process for gear pumps.

Direct numerical simulations of liquid–liquid dispersions in a SMX mixer under different inlet conditions

The internal dynamics of static mixers handling liquid–liquid flows have been comprehensively explored over the past decade. Although the effect of the inlet configuration is often overlooked, a few studies have suggested a relationship between the phases’ initial set-up and the performance of the mixer in terms of the droplet size distribution (DSD). Accordingly, different dispersed phase morphologies at the inlet of a SMX static mixer have been tested and their effect on the overall dispersion performance of the mixer has been evaluated based on the DSD and growth of interfacial area. In particular, three representative scenarios are considered: (1) Isolated cases, where one and three individual droplets are injected, mimicking a controlled syringe injection; (2) Numerous variable-sized droplets, simulating a pre-mixed/dispersed inlet; and (3) Jet inlet, emulating a standard phase injection from a gear pump. In addition, this study provides novel insight into the underlying physics dictating droplet deformation and breakage in SMX mixers for industrially-relevant scenarios. This can be achieved thanks to the massively-parallel high-fidelity three-dimensional direct numerical simulations computed with a robust hybrid front-tracking/level-set algorithm, which provides a wealth of information on intricate interfacial dynamics; this information cannot be obtained via experimental or volume-averaged modelling techniques implemented in past studies.

Pulsation Test and Analysis of Internal Gear Pump Used in Electro-hydraulic Actuator

The linear conjugate internal gear pump is widely used in the Electro-hydraulic Actuator (EHA) system because of its high efficiency and low noise, especially in the ship domain where vibration and noise requirements are very strict. To find out the reason, the calculation method of flow fluctuation and pressure pulsation at the pump outlet is obtained theoretically. First, the method of obtaining the two characteristic values of pump source flow pulsation Qs and pump source impedance Zs, and the data calculation and processing program are compiled by Matlab. Then the test platform was built, as well as the computer simulation and data collection. According to the theoretical method, the actual flow fluctuation and pressure pulsation at the pump outlet under different working conditions are measured and calculated respectively. The data of each working condition can be summarized and analyzed as: the test platform is reasonable and the data obtained from the test and calculation are reasonable; under the same frequency spectrum, the amplitude corresponding to the fundamental frequency of the motor pump is much larger than that of the pump tooth; under different working conditions, the variation trend of flow fluctuation and pressure pulsation corresponding to the fundamental frequency and the frequency doubling of the internal gear pump is obtained by testing; the specific values are smaller and suitable for the use in a silent system.

PLC Modification of Lubrication System for Mining Dump Trucks

The automatic lubrication system of the mining dump truck is provided with pressure by a hydraulic gear pump. The pressure sensor provides real-time working pressure feedback for the lubrication system, serving as a basis for the electromagnetic pressure relief valve control system. The lubrication condition of the articulated bearings in the mining dump truck has a significant impact on the truck's utilization rate. Proper lubrication is directly related to extending equipment lifespan and reducing equipment maintenance costs. By researching and analyzing the principles of the automatic lubrication control system for mining dump trucks, and considering the characteristics, types, and maintenance difficulties of lubrication system failures, we propose a PLC modification to the original control system. This modification aims to enhance system operational stability and reduce maintenance costs.

Analysis Of The Flow Pulsation Characteristics Of The Gear Pump Used in Electro-Hydrostatic Actuator

Linear conjugate internal gear pump has low noise and a smooth flow, but the mechanism of flow pulsation, especially the experiment, is seldom studied. In this paper, the flow rate formula of instantaneous, flow pulsation rate and relative volume change of the trapped oil cavity are derived by means of theoretical calculation. The pressure fluctuation characteristics of the trapped oil chamber and flow pulsation characteristics of the pump outlet are studied by using the three-dimensional fluid dynamics finite element simulation analysis method. According to the international standard of ISO10767-1-2015, the pump outlet flow pulsation test was conducted. The flow pulsation rate of a certain type of linear conjugate internal gear pump with a displacement of 10mL/r is about 6.35% under the condition of the speed of 750r/min and outlet pressure of 7.5MPa, and the flow pulsation is small.

Two-Stage Multi-Channel Fault Detection and Remaining Useful Life Prediction Model of Internal Gear Pumps Based on Robust-ResNet.

The internal gear pump is simple in structure, small in size and light in weight. It is an important basic component that supports the development of hydraulic system with low noise. However, its working environment is harsh and complex, and there are hidden risks related to reliability and exposure of acoustic characteristics over the long term. In order to meet the requirements of reliability and low noise, it is very necessary to make models with strong theoretical value and practical significant to accurately monitor health and predict the remaininglife of the internal gear pump. This paper proposed a multi-channel internal gear pump health status management model based on Robust-ResNet. Robust-ResNet is an optimized ResNet model based on a step factor h in the Eulerian approach to enhance the robustness of the ResNet model. This model was a two-stage deep learning model that classified the current health status of internal gear pumps, and also predicted the remaining useful life (RUL) of internal gear pumps. The model was tested in an internal gear pump dataset collected by the authors. The model was also proven to be useful in the rolling bearing data from Case Western Reserve University (CWRU). The accuracy results of health status classification model were 99.96% and 99.94% in the two datasets. The accuracy of RUL prediction stage in the self-collected dataset was 99.53%. The results demonstrated that the proposed model achieved the best performance compared to other deep learning models and previous studies. The proposed method was also proven to have high inference speed; it could also achieve real-time monitoring of gear health management. This paper provides an extremely effective deep learning model for internal gear pump health management with great application value.

Technology of Obtaining Mixed Alternative Fuel Based on Organic Substances for Mining Technological Transport Engines

Abstract In connection with the increase in the price of fuel based on hydrocarbons, the search and use of alternative types of fuel for machines in the mining and oil production industry is quite relevant today. Most of the existing alternative fuels by themselves cannot be considered as ready-to-use motor fuels. One of the ways to solve this problem is to use their mixtures with commercial fuels in certain ratios. This work deals with the development and research of the main characteristics of the mixer for obtaining mixed fuels based on diesel fuel and soybean oil, as well as the results of the study of the physical and operational properties of the obtained mixtures of different volume ratios of diesel fuel and soybean oil. The process of obtaining a mixed alternative fuel based on diesel fuel and soybean oil was implemented on a developed installation consisting of a mixer, the design of which is protected by a patent of Ukraine, and a gear pump. The study of the characteristics of the mixer as part of the installation showed that at a temperature of the components of the alternative fuel of 20°С, with a loss of full pressure on the mixer Δр ≈ (60-65) kPa, the volume consumption of soybean oil reached 10.7.10-6 m3/s. The time of preparation of the fuel mixture in the amount of 195 liters with a content of soybean oil of 10% ranged from 30 to 33 minutes. As research has shown, mixing soybean oil with diesel fuel in the amount of 5-50% vol. provides an improvement in viscosity-temperature properties and makes it possible to use such mixtures in diesel engines without changes in the design of the power supply system and regulation of fuel equipment, which characterizes soybean oil as a promising additive to diesel fuels to improve their technical and operational performance.

Study on Multi-flow Field Characteristics of Unloading Groove Spacing of Bidirectional Gear Pump

Improving the output flow quality of the high-precision micro bidirectional gear pump can effectively improve the position control accuracy and dynamic characteristics of the electro-hydraulic actuator. In order to meet the appeal requirements and reduce the vibration and noise of the gear pump and prolong its working life, this paper starts with the research of the key part of the gear pump–the unloading groove structure. The three characteristics of trapped oil phenomenon, cavitation phenomenon, and flow were used as key indices to evaluate gear pump performance. Using numerical simulation analysis, the dynamic grid simulation method was used to explore the influence of unloading groove spacing on the transient multi-flow field characteristics of the gear pump under conventional design range. Our results show that reducing the distance between unloading grooves can greatly reduce the trapped oil pressure and the amount of gas precipitation in the flow field, while reducing flow pulsation and improving volumetric efficiency. However, when the unloading groove spacing is too small, the instantaneous flow curve loses the pulsation characteristics and the flow stability decreases. Considering the influence of the gear pump on the accuracy of the electro-hydraulic actuator and the performance of the gear pump itself, the analytic hierarchy process was used to obtain the 1 mm unloading slot spacing, which best meets the engineering requirements of high flow accuracy and low vibration noise. The results provide a basis for work on the structural optimization of high-precision micro gear pumps.

ОПТИМІЗАЦІЯ КАСКАДНОЇ СХЕМИ ВИСОКОШВИДКІСНОЇ ЕКСТРУЗІЇ

Plastics are one of the most common materials. Due to its high technical and economical characteristics, this class of materials is used in almost all industries, that is why further growth of the production of plastic products is predicted. Today, the biggest problem in the field of polymer processing by extrusion is to ensure the best possible parameters of resource-energy efficiency of equipment. At the same time, the creating of compounds based on polymers is developing very actively, which requires more flexibility from extrusion lines, since a large number of compositions which differ in their characteristics can be developed on the base of a polymer. The factors listed above have led to cascade extrusion lines become increasingly wide-spread in industry today. Analysis of the extrusion equipment market showed that the schemes with a high-speed double-string extruder at the first stage is more popular. However, the desired mixing quality can be achieved by using a much simpler disc extruder. The article is a review that aims to determine the possibility and feasibility of more efficient arrangement of a cascade scheme for processing composite materials using a disk extruder. Theoretical and experimental studies have shown that melting processes are more efficient in the field of high shear rates at low pressures. Disk extruder is great option for that objective. In this scheme, it is proposed to use a dose feed disk extruder as a homogenizer, and a gear pump as a metering device which allows to reduce pressure and capacity fluctuations before forming device to less than 1%. As a result, it has been determined that the proposed design of the extrusion plant will be more energy efficient than the options on the market and will be able to significantly reduce pressure and performance fluctuations at the inlet to the forming device.

Функціональний портрет шестеренної гідравлічної машини

Increasing the efficiency of the functional performance of various mechanisms, including hydraulic gear pumps and motors, is one of the most important issues in the development of mechanical engineering. Special attention should be paid to the indicators of the volume flow rate and the torque. One of the ways is to study the mutual influence of the output parameters of the hydraulic gear machine. Some of the main parameters that determine the functional performance of a gear hydraulic machine are volume flow, power and torque, which in turn form the overall efficiency. It is necessary to create a functional portrait in order to determine the influence of these indicators on the overall efficiency and to improve the efficiency of the gear hydraulic machine. The resulting functional portrait will make it possible to determine the indicator for optimizing the operation of a gear hydraulic machine, both in pump mode and in motor mode. In turn, it will allow us to combine correlations with each other. In order to obtain the optimal indicators for building a functional portrait, a scheme for diagnosing a gear hydraulic machine in the pump-motor mode has been developed. An algorithm for its operation has been presented. As a result of the construction of a functional diagram of a gear hydraulic machine in pump mode, it was found that its operation has no inertia and its parameters are stable and dependent on the dimensional diagram. The orientation of the end bearings occurs during operation in pumping mode under frictional, sliding and dynamic conditions, which ensures improved sealing. On the other hand, the functional portrait of a gear hydraulic machine in motor mode has a zone of inertia, which can be stable or not, depending on the starting moment. Also, on the basis of the obtained functional portrait, it can be assumed that the probable cause of the failure of the gear pump and the motor during the acceptance tests may be the insufficient study of their interdependencies at the stage of development of the design documentation.