Abstract:Unbalanced radial force is one of the most urgent issues for internal gear pumps (IGPs) working at high working pressures. A numerical model for the prediction of the unbalanced radial force is essential for the structural design of gear pumps, facing the challenges of gear engagement description, dynamic mesh method, and so on. In this work, a three-dimensional computational fluid dynamics model of an IGP with a high working pressure was established based on the 2.5-dimensional dynamic mesh method, with cavit… Show more
“…Later, the hydraulic oil is discharged out of the chamber. Figure 1.Schematic diagram of a high-pressure IGP 20 .…”
Section: Theoretical Analysismentioning
confidence: 99%
“…The main test system of an IGP, 20 as shown in Figure 3, is mainly consisted of an oil tank, an inverter motor, a high-pressure gear pump, hydraulic valve blocks, sensors, and piping systems. The pump is driven by a 4-pole 110 kW induction inverter motor through the coupling, the flange connection and the speed-torque sensor.…”
“…Gear geometry and operating principle Figure 1 shows the main structure of a high-pressure IGP. 20 It has a pinion (gear shaft), i.e. an externally toothed gearwheel, which is arranged eccentrically in an internally toothed annulus and meshes with the annulus at one point on the circumference or in one section of the circumference.…”
In this paper, the flow ripple equation is derived to analyze the effect of working condition on pressure pulsations of an internal gear pump. Results indicate that working pressure has a significant effect on pressure fluctuation of the internal gear pump, while the rotating speed has a complex influence on the pressure pulsation behavior. Then, pressure pulsations of the internal gear pump under different working conditions are discussed by experimental investigations. Results show that the internal gear pump taken for analysis has a low-pressure pulsation at a high working pressure and a relatively high rotational speed. Regarding the frequency spectrum of the pressure pulsation, the dominant frequency is Z* fn, i.e. the product of the tooth number of the driving gear (gear shaft) and its rotational frequency for many working conditions, caused by the inevitable unsteady discharge process of gear pumps. It transforms to the rotational frequency of the gear shaft ( fn) for a high rotational speed or a high operating pressure, but to the rotating frequency of the internal gear ring (2/3 fn) only for a high operating pressure. The occurrence of the two frequencies (2/3 fn and fn) may result from the deformation of the gear ring and the gear shaft under the unbalanced radial forces caused by a high working pressure. Moreover, the frequency spectrum of the inlet pressure pulsation presents some differences from that of the outlet pressure pulsation. This is because the inlet pressure may be influenced by cavity generated at the suction side of the pump.
“…Later, the hydraulic oil is discharged out of the chamber. Figure 1.Schematic diagram of a high-pressure IGP 20 .…”
Section: Theoretical Analysismentioning
confidence: 99%
“…The main test system of an IGP, 20 as shown in Figure 3, is mainly consisted of an oil tank, an inverter motor, a high-pressure gear pump, hydraulic valve blocks, sensors, and piping systems. The pump is driven by a 4-pole 110 kW induction inverter motor through the coupling, the flange connection and the speed-torque sensor.…”
“…Gear geometry and operating principle Figure 1 shows the main structure of a high-pressure IGP. 20 It has a pinion (gear shaft), i.e. an externally toothed gearwheel, which is arranged eccentrically in an internally toothed annulus and meshes with the annulus at one point on the circumference or in one section of the circumference.…”
In this paper, the flow ripple equation is derived to analyze the effect of working condition on pressure pulsations of an internal gear pump. Results indicate that working pressure has a significant effect on pressure fluctuation of the internal gear pump, while the rotating speed has a complex influence on the pressure pulsation behavior. Then, pressure pulsations of the internal gear pump under different working conditions are discussed by experimental investigations. Results show that the internal gear pump taken for analysis has a low-pressure pulsation at a high working pressure and a relatively high rotational speed. Regarding the frequency spectrum of the pressure pulsation, the dominant frequency is Z* fn, i.e. the product of the tooth number of the driving gear (gear shaft) and its rotational frequency for many working conditions, caused by the inevitable unsteady discharge process of gear pumps. It transforms to the rotational frequency of the gear shaft ( fn) for a high rotational speed or a high operating pressure, but to the rotating frequency of the internal gear ring (2/3 fn) only for a high operating pressure. The occurrence of the two frequencies (2/3 fn and fn) may result from the deformation of the gear ring and the gear shaft under the unbalanced radial forces caused by a high working pressure. Moreover, the frequency spectrum of the inlet pressure pulsation presents some differences from that of the outlet pressure pulsation. This is because the inlet pressure may be influenced by cavity generated at the suction side of the pump.
“…Their results showed that the wear ring radial clearance had a significant effect on axial force, which cannot be ignored (Gantar et al, 2002). For other types of pumps, such as axial piston and gear pumps (Bergada et al, 2008;Y. Liu et al, 2019), the axial force problem has also been studied by many scholars.…”
Vaned mixed-flow pump is widely used for liquid transportation in industry and agriculture. The structural-asymmetricity induces large axial force which causes axial vibration and shaft system damage. In this study, impeller forces are analyzed and optimized based on numerical simulation and experiment. Balance holes and a balance plate are used in cooperation. Orthogonal experiment is conducted to analyze the effects of balance hole diameter, sealing clearance width on the hub, and balance plate clearance width on axial force at design condition. Then, BP-artificial neural network is established with Global Dynamic Criterion algorithm. Efficiency and axial force at design condition are chosen as optimization objectives. The results prove that optimized pump has lower axial force and higher efficiency at design condition. The head coefficient meets design requirement. Accordingly, a cooperative method named the 'Combining Hole-Plate Pressure Balancing Method', made by adding balance holes and installing a balance plate in the hub clearance chamber, is proposed. The method can effectively reduce axial force and improve the adverse effect of axial force on the pump without obvious influence on hydraulic performance. This study is significant as a means to reduce axial force, lessen damage to a shaft system, and improve operation stability.
This paper presents a numerical modeling approach for investigating crescent‐type internal gear pumps (CIGPs) considering radial micromotions of both gears. The modeling approach couples a lumped parameter pressure solver on the bulk fluid domain, with a transient computational fluid dynamics film simulator based on transient gap geometries solved from the gear loading forces. Simulation results on a commercial unit shows that for a wide range of operating conditions, the model gives volumetric efficiency predictions with errors less than 2 % comparing to measurements. To highlight the importance of considering radial micromotions, the paper also provides the results achieved assuming nominal position for both gears.
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