Abstract In this work, the investigation’s goal is to conduct experiments and simulations on the existing gear pump test rig setup. The various parameters are set and observed in the first section of ...the investigation. Calculations are done using these numbers to obtain the other testing results. Another section simulates 2-D fluid flow over an external gear pump and contrasts the findings of the experiment with the flow rate and efficiency at various discharge pressures. This study provides a clear understanding of the external gear pump’s numerical analysis as well as its actual analysis. For each discharge pressure at the end, a prediction of pressure at various locations within the pump’s fluid domain was made.
External gear pumps are among the most popular fluid power positive displacement pumps, however they often suffer of excessive flow pulsation transmitted to the downstream circuit. To meet the ...increasing demand of quiet operation for modern fluid power system, a better understanding of the ripple source of gear pumps is desirable. This paper presents a novel approach for the analysis of the ripple source of gear pumps based on decomposition into a kinematic component and a pressurization component. The pump ripple can be regarded as the superposition of the displacement solution and the pressurization solution. The displacement solution is driven by the kinematic flow, and it can be derived from the kinematic flow theory; instead, the pressurization solution can be approximated by overlapping the pressurization flow for a single displacement chamber. Furthermore, in this way the changes of these two components with modification of the delivery circuit are determined in both analytical and numerical ways. The result of this analysis provides a good interpretation of the pulsation simulated by a detailed lumped-parameter simulation model, thus showing its validity. The result also indicates that the response of two ripple sources to the change of the loading in the downstream hydraulic circuit is very different. These findings reveal the limitation of the traditional experimental method for determining the pump ripple, that new experimental methods which are more physics-based can be potentially formulated based on this work.
Micro-ORC systems are usually equipped with positive displacement machines such as expanders and pumps. The pumping system has to guarantee the mass flow rate and allows a pressure rise from the ...condensation to the evaporation pressure values. In addition, the pumping system supplies the organic fluid, characterized by pressure and temperature very close to the saturation. In this work, a CFD approach is developed to analyze from a novel point of view the behavior of the pumping system of a regenerative lab-scale micro-ORC system. In fact, starting from the liquid receiver, the entire flow path, up to the inlet section of the evaporator, has been numerically simulated (including the Coriolis flow meter installed between the receiver and the gear pump). A fluid dynamic analysis has been carried out by means of a transient simulation with a mesh morphing strategy in order to analyze the transient phenomena and the effects of pump operation. The analysis has shown how the accuracy of the mass flow rate measurement could be affected by the pump operation being installed in the same circuit branch. In addition, the results have shown how the cavitation phenomenon affects the pump and the ORC system operation compared to control system actions.
Increasing attention is being paid to remanufacturing due to environmental protection and resource saving. Disassembly, as an essential step of remanufacturing, is always manually finished which is ...time-consuming while robotic disassembly can improve disassembly efficiency. Before the execution of disassembly, generating optimal disassembly sequence plays a vital role in improving disassembly efficiency. In this paper, to minimise the total disassembly time, an enhanced discrete Bees algorithm (EDBA) is proposed to solve robotic disassembly sequence planning (RDSP) problem. Firstly, the modified feasible solution generation (MFSG) method is used to build the disassembly model. After that, the evaluation criterions for RDSP are proposed to describe the total disassembly time of a disassembly sequence. Then, with the help of mutation operator, EDBA is proposed to determine the optimal disassembly sequence of RDSP. Finally, case studies based on two gear pumps are used to verify the effectiveness of the proposed method. The performance of EDBA is analysed under different parameters and compared with existing optimisation algorithms used in disassembly sequence planning (DSP). The result shows the proposed method is more suitable for robotic disassembly than the traditional method and EDBA generates better quality of solutions compared with the other optimisation algorithms.
This article presents the modeling, simulation and experimental validation of the movement of the floating bearing bushing in an external gear pump. As a starting point, a complete pump ...parameterization was carried out through standard tests, and these parameters were used in a first bond graph model in order to simulate the gear pump behavior. This model was experimentally validated under working conditions in field tests. Then, a sophisticated bond graph model of the movement of the floating bushing was developed from the equations that define its lubrication. Finally, as a result, both models were merged by integrating the dynamics of the floating bushing bearing with the variation of the characteristic parameters (loss coefficients). Finally, the final model was experimentally validated both in laboratory and field tests by assembling the pump in a drilling machine to drive the auxiliary movements. The novelty of this article is the conception and construction of a simple and experimentally validated tool for the study of a gear pump, which relates its macroscopic behavior as a black box (defined by the loss coefficients) to the internal changes of the unit (defined by its internal lubrication).
•The obstacle-avoiding path of robot's end-effector in the robotic disassembly process is considered.•The weights of indicators are calculated by the analytic network process.•The improved discrete ...Bees algorithm performs better than the other three optimization algorithms in solution quality.•The collaborative optimization problem helps to improve the disassembly efficiency.
Remanufacturing helps to reduce manufacturing cost and environmental pollution by reusing end-of-life products. Disassembly is an inevitable process of remanufacturing and it is always finished by manual labor which is high cost and low efficiency while robotic disassembly helps to cover these shortages. Before the execution of disassembly, well-designed disassembly sequence and disassembly line balancing solution help to improve disassembly efficiency. However, most of the research used for disassembly sequence planning and disassembly line balancing problem is only applicable to manual disassembly. Also, disassembly sequence planning and disassembly line balancing problem are separately studied. In this paper, an improved discrete Bees algorithm is developed to solve the collaborative optimization of robotic disassembly sequence planning and robotic disassembly line balancing problem. Robotic workstation assignment method is used to generate robotic disassembly line solutions based on feasible disassembly solutions obtained by the space interference matrices. Optimization objectives of the collaborative optimization problem are described, and the analytic network process is used to assign suitable weights to different indicators. With the help of variable neighborhood search, an improved discrete Bees algorithm is developed to find the optimal solution. Finally, based on a gear pump and a camera, case studies are used to verify the effectiveness of the proposed method. The results under different cycle time of robotic disassembly line are analyzed. Under the best cycle time, the performance of the improved discrete Bees algorithm under different populations and iterations are analyzed and compared with the other three optimization algorithms. The results under different assessment methods and scenarios are also analyzed.
An external gear pump is a relatively simple and inexpensive pump, that is used in a variety of production systems. Numerous works have studied the external gear pump using numerical simulations; ...however, typically low‐viscosity fluids and turbulent flow conditions are considered. Previous work of the authors focused on predicting the output fluctuation and the volumetric efficiency of an external gear pump processing high‐viscosity fluids using a 2D representation. For certain conditions, backflow through all clearances could occur, resulting in a drop in volumetric efficiency. This calls for a full 3D model. Furthermore, high residence time zones are observed in the inflow channel of the pump. The 3D shape of these zones is still unknown. The aim of this work is to investigate the effect of the axial clearances on the performance of the external gear pump. A 3D mesh is generated by extruding the 2D mesh in the third direction, resulting in prism elements. This reduces the required number of elements and therewith makes the simulations computationally feasible. Introducing the axial clearances results in a lower efficiency compared to the 2D simulations. With particle tracking, the high residence time zones in the inflow channel are visualized in the 3D simulations.
In extrusion processes, external gear pumps are frequently used to transport all kinds of fluids. 3D simulations are performed using the finite element method to investigate the relative importance of the radial and axial clearances in the pump. Particle tracking reveals zones with infinite residence time.
In comparison to involute internal gear pumps, conjugated straight-line internal gear pumps have the advantages of smaller trapped volume, lower flow ripple, and higher reliability. Conjugated ...straight-line internal gear pumps were invented by Truninger in 1966; however, because of their unique line type, the main characteristics of these pumps are still not completely understood. Internal gear pairs are the key component of these pumps. To better understand the performance of these pumps, the present research focused on the design of an internal gear pair. A numerical model was developed to demonstrate the design method of the conjugated straight-line internal gear pair. To point out the effective engagement of the gear pair, three fundamental requirements were considered—a conjugated point existed in the tooth profile, no interference occurred during the meshing process, and the overlap coefficient was greater than one. Furthermore, according to the design of the gear pair, flow characteristics and some optimization suggestions for tooth parameters were proposed. The main characteristics of the gear pair were compared with those of an involute gear pair. Finally, a conjugated straight-line internal gear pair machined by the linear cutting method was tested, and the obtained results revealed that the design method was correct.
•A novel model for curve-constricted leakage flows in hydraulic gear pumps is presented.•The flow model is applicable over a wide range of flow regimes including localized cavitation.•The model is ...developed in dimensionless form based on sets of CFD simulations.•Model validation is achieved through experiments conducted on a custom test apparatus.
The internal leakage flows in external gear and gerotor pumps are often represented by flow through curved constrictions. The nature of this flow can vary from laminar to turbulent and the flow can experience localized cavitation too. In the current literature, there is a scarcity of techniques for accurately modelling such curve-constricted flows which limits the accuracy of the current simulation tools for gear pumps.
This paper presents a novel flow model for curve-constricted geometries that is applicable over a wide range of flow regimes including localized cavitation. Using a dimensionless form, the proposed model characterizes the constriction flow velocity as the function of the constriction shape, the pressure difference, and a properly defined cavitation indicator. The functional relationships between these dimensionless parameters are developed based on CFD simulations. The flow model is validated by the means of several experiments conducted on a custom test apparatus.
The model presented in this paper can be incorporated in the lumped parameter simulation tools widely used for modelling gear pumps, improving their accuracy in predicting the internal leakages. Consequently, this model will also aid the development of novel energy efficient gear pump designs, where such leakages are kept to a minimum.
This article presents theoretical and experimental calculations of the minimum thickness of a compensation lip used in external gear pumps. Pumps of this type are innovative technical solutions in ...which circumferential backlash (clearance) compensation is used to improve their volumetric and overall efficiency. However, constructing a prototype of such a pump requires long-lasting research, and the compensation lip is its key object, due to the fact that it is an element influenced by a notch and that it operates in unfavorable conditions of strong fatigue stresses. The theoretical calculations presented in this article are based on identifying maximum stress values in a fatigue cycle and on implementing the stress failure condition and the conditions related to the required value of the fatigue safety factor. The experimental research focuses on static bending tests of the lips as well as on the fatigue loading of the lips in series of tests at increasing stress values until lip failure due to fatigue. The tests allowed the minimum lip thickness to be found for the assumed number of fatigue cycles, which is 2.5 times the number of cycles used in wear margin tests.
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